Note: Descriptions are shown in the official language in which they were submitted.
20150~8
BACKGROUND OF THE INVENTION
The present invention relates to nitrogen
containing grafted ethylene copolymers useful as multi-
functional viscosity index (V.I.) improver additives, e.g.,
viscosity index improvers-dispersants, for oleaginous
compositions, particularly fuel oils and lubricating oils,
methods for preparing said grafted ethylene copolymers, and
to oleaginous compositions containing these nitrogen
containing grafted copolymers. More specifically t~e
instant invention relates to a copolymer of ethylene with
other alpha-olefins as a backbone, said copolymer comprised
of segmented copolymer chains with compositions which are
intramolecularly heterogeneous and intermolecularly
homogeneous, grafted with ethylenically unsaturated
carboxylic acid material and reacted with polyamine
containing one primary amino group and at least one
secondary amino group. The additives of the instant
invention provide oleaginous compositions, particularly
lubricating oil compositions, exhibiting improved low
temperature viscometric properties compared to conventional
nitrogen containing grafted ethylene-alpha-olefin
copolymers.
The concept of derivatizing V.I. improving high
molecular weight ethylene and alpha-olefin copolymers with
acid moieties such as maleic anhydride, followed by
reaction with an amine or an amine and a carboxylic acid
component to form a V.I.-dispersant oil additive is known
and is disclosed, inter alia, in the following patents:
U.S. Pat. No. 3,316,177 teaches ethylene
copolymers such as ethylene-propylene, or ethylene-
propylene-diene, which are heated to elevated temperatures
20150~8
in the presence of oxygen so as to oxidize the polymerand
cause its reaction with maleic anhydride which is present
during the oxidation. The resulting polymer can then be
reacted with alkylene polyamines.
U.S. Pat. No. 3,326,804 teaches reacting ethylene
copolymers with oxygen or ozone, to form a hydroperoxidized
polymer, which is grafted with maleic anhydride followed by
reaction with polyalkylene polyamines.
U.S. Pat. No. 4,089,794 teaches grafting the
ethylene copolymer with maleic anhydride using peroxide in
a lubricating oil solution, wherein the grafting is
preferably carried out under nitrogen, followed by reaction
with polyamine.
U.S. Pat. No. 4,137,185 teaches reacting Cl to
C30 mono carboxylic acid anhydrides, and dicarboxylic
anhydrides, such as acetic anhydride, succinic anhydride,
etc. with an ethylene copolymer reacted with maleic
anhydride and a polyalkylene polyamine to inhibit cross
linking and viscosity increase due to further reaction of
any primary amine groups which were initially unreacted.
U.S. Pat. No. 4,144,181 is similar to 4,137,185 in
that it teaches using a sulfonic acid to inactivate the
remaining primary amine groups when a maleic anhydride
grafted ethylene-propylene copolymer is reacted with a
polyamine.
U.S. Pat. No. 4,169,063 reacts an ethylene
copolymer in the absence of oxygen and chlorine at
temperatures of 150~ to 250~C with maleic anhydride
followed by reaction with polyamine.
A number of prior disclosures teach avoiding the
use of polyamine having two primary amine groups to thereby
reduce cross-linking problems which become more of a
problem as the number of amine moieties added to the
polymer molecule is increased in order to increase
dispersancy.
20150~8
~_ - 3 -
German Published Application No. P3025274.5
teaches an ethylene copolymer reacted with maleic anhydride
in oil using a long chain alkyl hetero or oxygen containing
amine.
U.S. Pat. No. 4,132,661 grafts ethylene copolymer,
using peroxide and/or air blowing, with maleic anhydride
and then reacts with primary-tertiary diamine.
U.S. Pat. No. 4,160,739 teaches an ethylene
copolymer which is grafted, using a free radical technique,
with alternating maleic anhydride and a second polymer-
izable monomer such as methacrylic acid, which materials
are reacted with an amine having a single primary, or a
single secondary, amine group.
U.S. Pat. No. 4,171,273 reacts an ethylene
copolymer with maleic anhydride in the presence of a free
radical initiator and then with mixtures of C4 to C12
n-alcohol and amine such as N-aminopropylmorpholine or
dimethylamino propyl amine to form a V.I.-dispersant-pour
depressant additive.
U.S. Pat. No. 4,219,432 teaches maleic anhydride
grafted ethylene copolymer reacted with a mixture of an
amine having only one primary group together with a second
amine having two or more primary groups.
German published application No. 2753569.9 shows
an ethylene copolymer reacted with maleic anhydride by a
free-radical technique and then reacted with an amine
having a single primary group.
German published application No. 2845288 grafts
maleic anhydride on an ethylene-propylene copolymer by
thermal grafting at high temperatures and then reacts with
amine having one primary group.
French published application No. 2423530 grafts
maleic anhydride on an ethylene-propylene copolymer with
maleic anhydride at 150~ to 210~C followed by reaction with
an amine having one primary or secondary group.
21~1~M5~
- 4
The early patents such as U.S. Pat. Nos. 3,316,177
and 3,326,804 taught the general concept of grafting an
ethylene-propylene copolymer with maleic anhydride and then
reacting with a polyalkylene polyamine such as polyethylene
amines. Subsequently, U.S. Pat. No. 4,089,794 was directed
to using an oil solution for free radical peroxide grafting
the ethylene copolymer with maleic anhydride and then
reaction with the polyamine. This concept had the
advantage that by using oil, the entire reaction could be
carried out in an oil solution to form an oil concentrate,
which is the commercial form in which such additives are
sold. This was an advantage over using a volatile solvent
for the reactions, which has to be subsequently removed and
replaced by oil to form a concentrate. Subsequently, in
operating at higher polyamine levels in order to further
increase the dispersing effect, increased problems occurred
with the unreacted amine groups corss-linking and thereby
causing viscosity increase of the oil concentrate during
storage and subsequent formation of haze and in some
instances gelling. Even though one or more moles of the
ethylene polyamine was used per mole of maleic anhydride
during imide formation, cross-linking became more of a
problem as the nitrogen content of the polymers was
increased. One solution was to use the polyamines and then
to react the remaining primary amino groups with an acid
anhydride, preferably acetic anhydride, of U.S. Pat. No.
4,137,185 or the sulfonic acid of U.S. Pat. No. 4,144,181.
The cross-linking problem could also be minimized by
avoidance of the ethylene polyamines and instead using
amines having one primary group which would react with the
maleic anhydride while the other amino groups would be
tertiary groups which were substantially unreactive.
Patents or published applications showing the use of such
primary-tertiary amines noted above are U.S. Pat. No.
4,219,432, wherein a part of the polyamine was replaced
2015058
,_ s
with a primary-tertiary amine; U.S. Pat. No. 4,132,661;
U.S. Pat. No. 4,160,739; U.S. Pat. No. 4,171,273; German
No. P2753569.9; German No. 2,845,288; and French No.
2,423,530.
U.S. Pat. No. 4,516,104 and 4,632,769 represented
a further improvement over the art in that they permitted
the utilization of the generally less expensive polyamines
having two primary amine groups, while achieving good
dispersancy levels, inhibiting cross-linking and allowing
initiator, e.g., peroxide, grafting in oil.
U.S. Patent No. 4,517,104 discloses polymeric
viscosity index (V.I.) improver-dispersant additives for
petroleum oils, particularly lubricating oils, comprising a
copolymer of ethylene with one or more C3 to C28
alpha-olefins, preferably propylene, which have been
grafted with acid moieties, e.g., maleic anhydride,
preferably using a free radical initiator in a solvent,
preferably lubricating oil, and then reacted with a mixture
of a carboxylic acid component, preferably an alkyl
succinic anhydride, and a polyamine having two or more
primary amine groups. Or the grafted polymer may be
reacted with said acid component prereacted with said
polyamine to form salts, amides, imides, etc. and then
reacted with said grafted olefin polymer. These reactions
can permit the incorporation of varnish inhibition and
dispersancy into the ethylene copolymer while inhibiting
cross-linking or gelling.
U.S. Patent No. 4,632,769 discloses oil soluble
viscosity improving ethylene copolymers such as copolymers
of ethylene and propylene, reacted or grafted with
ethylenically unsaturated carboxylic acid moieties,
preferably maleic anhydride moieties, and then reacted with
polyamines having two or more primary amine groups and a
C22 to C28 olefin carboxylic acid component, preferably
alkylene polyamine and alkenyl succinic anhydride,
~ - 6 - 2 ~ ~ 5 ~ ~ ~
respectively. These reactions can permit the incorporation
of varnish inhibition and dispersancy in~o the ethylene
copolymer while inhibiting cross-linking or gelling.
While the additives disclosed in U.S. Pat. No.
4,517,104 and 4,632,769 provide quite useful oil
compositions there is a need for oil compositions which
exhibit better low temperature viscometric properties than
those possessed by conventional oil compositions.
The problem of providing V.I. oil additives
exhibiting improved low temperature viscometric properties
is addressed in U.S. Patent No. 4,804,794. U.S. Patent No.
4,804,79~ discloses segmented copolymers of ethylene and at
least one other alpha-olefin monomer, each copolymer being
intramolecularly heterogeneous and intermolecularly
homogeneous and at least one segment of the copolymer,
constituting at least 10% of the copolymer's chain, being a
crystallizable segment. These copolymers are disclosed as
exhibiting good mechanical properties such as good shear
stability and as being useful V.I. improvers which provide
lubricating oils having highly desirable viscosity and
pumpability properties at low temperatures. However, these
copolymers are disclosed as being V.I. improvers, and
there is no disclosure of grafting said copolymers with an
ethylenically unsaturated carboxylic acid material and
thereafter reacting these grafted copolymers with
polyamines containing one primary amine group and at least
one secondary amine group to provide multifunctional
viscosity index improver additives, e.g., viscosity index
improver-dispersant additives, for oleaginous
compositions. Indeed, it was heretofore generally believed
that these ethylene copolymers could not be grafted with
conventional ethylenically unsaturated grafting materials
and thereafter reacted with nitrogen containing compounds
such as polyamines without substantially deleteriously or
,
!
~015058
adversely affecting, i.e., broadening, the narrow molecular
weight distribution (MWD). It was believed that this
deleterious effect upon the narrow MWD would have a
concomitant deleterious effect upon the intermolecular
homogeneity, microstructure (intramolecular heterogeneity),
and upon the advantageous low temperature viscometric
properties. It has been surprisingly discovered that
oleaginous compositions containing ethylene copolymers of
the instant invention grafted with ethylenically
monounsaturated carboxylic acid material and reacted with
polyamine containing one primary amine group and one or
more secondary amine groups to form nitrogen containing
grafted ethylene copolymers exhibit better low temperature
viscometric properties than those containing conventional
nitrogen containing grafted ethylene copolymers. Thus, the
multifunctional viscosity index improver additives of the
instant invention provide oleaginous compositions,
particularly lubricating oil compositions, exhibiting
dispersancy and better low temperature viscometric
characteristics than conventional multifunctional viscosity
index improvers comprised of nitrogen or ester containing
grafted conventional ethylene copolymers.
SUMMARY OF THE INVENTION
The present invention is directed to oil soluble
nitrogen containing grafted ethylene copolymers useful as
multifunctional viscosity index improvers or modifiers,
e.g., as V.I. improver-dispersant additives, in oleaginous
compositions. The nitrogen containing grafted ethylene
copolymers of the instant invention provide oleaginous
compositions, in particular lubricating oil compositions,
exhibiting improved viscometric properties, particularly
highly desirable viscosity properties at low temperatures,
and dispersancy characteristics.
_ - 8 - ~ 5 8
The ethylene copolymers of the instant invention
are grafted with an ethylenically mono-unsaturated
carboxylic acid grafting material and the grafted ethylene
copolymers are then reacted with at least one polyamine
cont~in;ng only one primary amino group, at least one
secondary amino group, and preferably no tertiary amino
groups.
The copolymers which are grafted and reacted with
the polyamine containing one primary amine group, one or
more (i.e., one to about 6) secondary amine groups, and
preferably no tertiary amine groups are disclosed in U.S.
Patent No. 4,804,794. These copolymers are segmented
copolymers of ethylene and at least one other alpha-olefin
monomer; each copolymer is intramolecularly heterogeneous
and intermolecularly homogeneous and at least one segment of
the copolymer, constituting at least 10% of the copolymer's
chain, is a crystallizable segment. For the purposes of
this application, the term "crystallizable segment" is
defined to be each segment of the copolymer chain having a
number-average molecular weight of at least 700 wherein the
ethylene content is at least 57 wt.%. The remaining
segments of the copolymer chain are herein termed the "low
crystallinity segments" and are characterized by an average
ethylene content of not greater than about 53 wt%.
Furthermore, the molecular weight distribution (MWD) of
copolymer is very narrow. It is well known that the-
breadth of the molecular weight distribution can be
characterized by the ratios of various molecular weight
averages. For example, an indication of a narrow MWD in
accordance with the present invention is that the ratio of
weight to number-average molecular weight (~w/~n) is less
than 2. Alternatively, a ratio of the z-average molecular
weight to the weight-average molecular weight (~z/Mw)
of less than 1.8 typifies a narrow MWD in accordance with the
. ~ ~
2015058
g
present invention. It is known that a portion of the
property advantages of copolymers in accordance with the
present invention are related to these ratios. Small
weight fractions of material can disproportionately
influence these ratios while not significantly altering the
property advantages which depend on them. For instance,
the presence of a small weight fraction (e.g. 2~) of low
molecular weight copolymer can depress ~n~ and thereby raise
/Mn above 2 while maintaining ~z/ ~ less than 1.8.
Therefore, the copolymer reactants, in accordance with the
present invention, are characterized by having at least one
of ~W/Mn less than 2 and ~z/Mw less than 1.8. The copolymer
reactant comprises chains within which the ratio of the
monomers varies along the chain length. To obtain the
intramolecular compositional heterogeneity and narrow MWD,
the ethylene copolymer reactants are preferably made in a
tubular reactor.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the instant invention there are
provided nitrogen containing polymeric materials useful as
multifunctional viscosity index improvers, particularly
viscosity index improver-dispersant additives, for
oleaginous materials, particularly lubricating oils, which
are comprised of (i) certain specific types of ethylene and
alpha-olefin copolymers grafted with (ii) ethylenically
monounsaturated carboxylic acid material, and (iii) reacted
with polyamine containing one primary amino group and at
least one secondary amino group.
More particularly, in one aspect of the instant
invention, hereinafter referred to as Aspect A these
polymeric materials are comprised of the reaction products
of:
20150~8
-- 10 --
(i) backbone copolymer of ethylene and at least
one other alpha-olefin monomer, said copolymer comprising
intramolecularly heterogeneous and intermolecularly
homogeneous copolymer chains containing at least one
crystallizable segment of methylene units and at least one
low crystallinity ethylene-alpha-olefin copolymer segment,
wherein said at least one crystallizable segment comprises
at least about 10 weight percent of said copolymer chain
and contains at least about 57 weight percent ethylene,
wherein said low crystallinity segment contains not greater
than about 53 weight percent ethylene, and wherein said
copolymer has a molecular weight distribution characterized
by at least one of a ratio of ~w/~n of less than 2 and a
ratio of ~z/~w of less than 1.8, and wherein at least two
portions of an individual intramolecularly heterogeneous
chain, each portion comprising at least 5 weight percent of
said chain, differ in composition from one another by at
least 7 weight percent ethylene; grafted with ethylenically
monounsaturated carboxylic acid material; and
(ii) polyamine containing one primary amine group
and at least one secondary amine group.
In another aspect of the instant invention,
hereinafter referred to as Aspect B, the nitrogen containig
grafted ethylene copolymers are comprised of the reaction
products of:
(i) backbone copolymer of ethylene and at least
one other alpha-olefin monomer, said copolymer comprising
intramolecularly heterogeneous and intermolecularly
homogeneous copolymer chains containing at least one
crystallizable segment of methylene units and at least one
low crystallinity ethylene-alpha-olefi copolymer segment,
wherein said at least one crystallizable segment comprises
at least about 10 weight percent of said copolymer chain
and contains at least about 57 weight percent ethylene,
wherein said low crystallinity segment contains not greater
2015058
than about 53 weight percent ethylene, and wherein said
copolymer has a molecular weight distribution characterized
by at least one of a ratio of ~W/~n ~f
less than 2 and a ratio of ~z/~w of less
than 1.8, and wherein at least two portions of an
individual intramolecularly heterogeneous chain, each
portion comprising at least 5 weight percent of said chain,
differ incomposition from one another by at least 7 weight
percent ethylene; grafted with ethylenically
monounsaturated carboxylic acid material;
(ii) carboxylic acid component comprising
C12-C49 hydrocarbyl substituted dicarboxylic acid or
anhdride, C50-C400 hydrocarbyl substituted
monocarboxylic acid, or C50-C400 hydrocarbyl
substituted dicarboxylic acid, or anhydride; and
(iii) polyamine containing one primary amine group
and at least one secondary amine group.
In yet a further aspect of the instant invention
the nitrogen containing carboxylic acid material grafted
ethylene copolymers of either aspect A or B are reacted or
post-treated with a viscosity stabilizing or end capping
agent such as, for example, a C12-C18 hydrocarbyl
substituted dicarboxylic anhydride.
When the nitrogen containing grafted ethylene
copolymers of the instant invention are incorporated into
oleaginous materials such as lubricating oils the resultant
oleaginous compositions exhibit better low temperature
viscometric properties than oleaginous compositions
containing conventional nitrogen containing grafted
ethylene copolymers. Furthermore, the nitrogen containing
grafted ethylene copolymers of this invention function as
dispersants in oleaginous compositions and generally
exhibit substantially similar dispersancy efficacy as
conventional nitrogen containing grafted ethylene
copolymers falling outside the scope of the instant
invention.
20150~8
- 12 -
EthYlene and Alpha-Olefin Copolymer
The ethylene and alpha-olefin copolymers defined
as (i) hereinafore are copolymers of ethylene with at least
one other alpha-olefin comprised of segmented copolymer
chains with compositions which are intramolecularly
heterogeneous and intermolecularly homogeneous.
For convenience, certain terms that are repeated
throughout the present specification are defined below:
a. Inter-CD defines the compositional variation,
in terms of ethylene content, among polymer chains. It is
expressed as the minimum deviation (analogous to a standard
deviation) in terms of weight percent ethylene, from the
average ethylene composition for a given copolymer sample
needed to include a given weight percent of the total
copolymer sample, which is obtained by excluding equal
weight fractions from both ends of the distribution. The
deviation need not be symmetrical. When expressed as a
single number, for example 15% Inter-CD, it shall mean the
larger of the positive or negative deviations. For
example, for a Gaussian compositional distribution, 95.5%
of the polymer is within 20 wt.% ethylene of the mean if
the standard deviation is 10%. The Inter-CD for 95.5 wt.%
of the polymer is 20 wt.% ethylene for such a sample.
b. Intra-CD is the compositional variation, in
terms of ethylene, within a copolymer chain. It is
expressed as the minimum difference in weight (wt.%)
ethylene that exists between two portions of a single
copolymer chain, each portion comprising at least 5 weight
% of the chain.
c. Molecular weight distribution (MWD) is a
measure of the range of molecular weights within a given
copolymer sample. It is characterized in terms of at least
one of the ratios of weight-average to number-average
molecular weight, MW/Mn, and z-average to
weight-average molecular weight, ~z/~w~ where:
' 2015058
- 13 -
-- ~ NiMi
~ NiMi
Mn ~NiMi ~ and
~ Ni
Mz = ~NiMi
~ NiMi2
wherein Ni is the number of molecules of molecular weight
Mi .
d. Viscosity Index (V.I.) is the ability of a
lubricating oil to accommodate increases in temperature
with a minimum decrease in viscosity. The greater this
ability, the higher the V.I. Viscosity Index is determined
according to ASTM D2270.
The instant copolymers are segmented copolymers of
ethylene and at least one other alpha-olefin monomer
wherein the copolymer's chain contains at least one
crystallizable segment of ethylene monomer units, as will
be more completely described below, and at least one low
crystallinity ethylene-alpha-olefin copolymer segment,
where in the low crystallinity copolymer segment is
characterized in the unoriented bulk state after at least
24 hours annealing by a degree of crystallinity of less
than about 0.2% at 23~C, and wherein the copolymer's chain
is intramolecularly heterogeneous and intermolecularly
homogeneous, and has an MWD characterized by at least one
of Mw/Mn of less than 2 and Mz/Mw of
less than 1.8. The crystallizable segments comprise from
about 10 to 90 wt.%, preferably from about 20 to 85 wt.%,
2015058
- 14 -
of the total copolymer chain, and contain an average
ethylene content which is at least about 57 wt.%,
preferably at least about 62 wt.%, and more preferably at
least about 63 wt.% and which is not greater than 95 wt.%,
more preferably <85%, and most preferably <75 wt.% (e.g.,
from about 58 to 68 wt.%). The low crystallinity copolymer
segments comprise from about 90 to 10 wt.%, preferably from
about 80 to 15 wt.%, and more preferably from about 65 to
wt.%, of the total copolymer chain, and contain an
average ethylene content of from about 20 to 53 wt.%,
preferably from about 30 to 50 wt.%, and more preferably
from about 35 to 50 wt.%. The copolymers comprise
intramolecularly heterogeneous chain segments wherein at
least two portions of an individual intramolecularly
heterogeneous chain, each portion comprising at least 5
weight percent of the chain and having a molecular weight
of at least 7000 contain at least 5 wt.% ethylene and
differ in composition from one another by at least 5 weight
percent ethylene, wherein the intermolecular compositional
dispersity of the polymer is such that 95 wt. % of the
polymer chains have a composition 15% or less different in
ethylene from the average weight percent ethylene
composition, and wherein the copolymer is characterized by
at least one or a ratio of ~W/Mn of less than 2 and
a ratio of Mz/~w of less than 1.8.
As described above, the copolymers will contain at
least one crystallizable segment rich in methylene units
(hereinafter called an "M" segment) and at least one low
crystallinity ethylene-alpha-olefin copolymer segment
(hereinafter called a "T" segment). The copolymers may be
therefore illustrated by copolymers selected from the group
consisting of copolymer chain structures having the
following segment sequences:
M-T, (I)
Tl-(M-T2)x and (II)
Tl-(Ml-T2)y-M2 (III)
201~0~8
- 15 -
wherein M and T are defined above, Ml and M2 can be the
same or different and are each M segments, Tl and T2
can be the same or different and are each T segments, x is
an integer of from 1 to 3 and y is an integer of 1 to 3.
In structure II (x=l), the copolymer's M segment
is positioned between two T segments, and the M segment can
be positioned substantially in the center of the polymer
chain (that is, the Tl and T2 segments can be
substantially the same molecular weight and the sum of the
molecular weight of the Tl and T2 segments can be
substantially equal to the molecular weight of the M
segment), although this is not essential to the practice of
this invention. Preferably, the copolymer will contain
only one M segment per chain. Therefore, structures I and
II (x=l) are preferred.
Preferably, the M segments and T segments of the
copolymer are located along the copolymer chain so that
only a limited number of the copolymer chains can associate
before the steric problems associated with packing the low
crystallinity T segments prevents further agglomeration.
Therefore, in a preferred embodiment, the M segment is
located near the center of the copolymer chain and only one
M segment is in the chain.
As will be shown below, a copolymer of the
structure
Ml _ (T-M2) (IV)
(wherein Ml, M2 and T are as defined above, and wherein
z is an integer of at least 1) are undesirable as viscosity
modifier polymers. It has been found that solutions of
structure IV copolymers in oil tend to gel even when the M
201~058
- 16 -
and T portions have exactly the same composition and
molecular weight as structure II copolymers (with x=z=l).
It is believed this poor viscosity modifier performance is
due to the inability of a center T segment to sterically
stabilize against association.
The M segments of the copolymers of this invention
comprise ethylene and can also comprise at least one other
alpha-olefin, e.g., containing 3 to 18 carbon atoms. The T
segments comprise ethylene and at least one other
alpha-olefin, e.g., alpha-olefins containing 3 to 18 carbon
atoms. The M and T segments can also comprise other
polymerizable monomers, e.g., non-conjugated dienes or
cyclic mono-olefins.
Since the present invention is considered to be
most preferred in the context of ethylene-propylene (EPM)
copolymers it will be described in detail in the context of
EPM.
Copolymer (i)(a) in accordance with the present
invention is preferably made in a tubular reactor. When
produced in a tubular reactor with monomer feed only at the
tube inlet, it is known at the beginning of the tubular
reactor, ethylene, due to its high reactivity , will be
preferentially polymerized. The concentration of monomers
in solution changes along the tube in favor of propylene as
the ethylene is depleted. The result, with monomer feed
only at the inlet, is copolymer chains which are higher in
ethylene concentration in the chain segments grown near the
reactor inlet (as defined at the point at which the
polymerization reaction commences), and higher in propylene
concentration in the chain segments formed near the reactor
outlet. These copolymer chains are therefore tapered in
composition. An illustrative copolymer chain of
ethylene-propylene is schematically presented below with E
representing ethylene constituents and P representing
propylene constituents in the chain:
' 20150~8
17 -
1 2 3 4
Segment: E-E-E-E-P-E-E-E-P-P-E-E-P-P-P-E-P-P-P-P
As can be seen from this illustrative schematic
chain, the far left-hand segment (1) thereof represents
that portion of the chain formed at the reactor inlet where
the reaction mixture is proportionately richer in the more
reactive constituent ethylene. This segment comprises four
ethylene molecules and one propylene molecule. However, as
subsequent segments are formed from left to right with the
more reactive ethylene being depleted and the reaction
mixture proportionately increasing in propylene
concentration, the subsequent chain segments become more
concentrated in propylene. The resulting chain is intra-
molecularly heterogeneous.
The property, of the copolymer discussed herein,
related to intramolecular compositional dispersity
(compositional variation within a chain) shall be referred
to as Intra-CD, and that related to intermolecular
compositional dispersity (compositional variation between
chains) shall be referred to as Inter-CD.
For copolymers in accordance with the present
invention, composition can vary between chains as well as
along the length of the chain. An object of this invention
is to minimize the amount of inter-chain variation. The
Inter-CD can be characterized by the difference in
composition between the copolymer fractions containing the
highest and lowest quantity of ethylene. Techniques for
measuring the breadth of the Inter-CD are known as
illustrated in "Polymerization of ethylene and propylene to
amorphous copolymers with catalysts of vanadium oxychloride
and alkyl aluminum halides"; E. Junghanns, A. Gumboldt and
G. Bier; Makromol. Chem., V. 58 (12/12/62): 18-42, wherein
a p-xylene/dimethylformamide solvent/non-solvent was used
'_ 20150~
- 18 -
to fractionate copolymer into fractions of differing
intermolecular composition. Other solvent/non-solvent
systems can be used as hexane/2 propanol, as will be
discussed in more detail below.
The Inter-CD of copolymer in accordance with the
present invention is such that 95 wt. % of the copolymer
chains have an ethylene composition that differs from the
average weight percent ethylene composition by 15 wt. % or
less. The preferred Inter-CD is about 13% or less, with
the most preferred being about 10% or less. In comparison,
Junghanns et al. found that their tubular reactor copolymer
had an Inter-CD of greater than 15 wt. %.
Broadly, the Intra-CD of copolymer in accordance
with the present invention is such that at least two
portions of an individual intramolecularly heterogeneous
chain, each portion comprising at least 5 weight percent of
the chain, differ in composition from one another by at
least 7 weight percent ethylene. Unless otherwise
indicated, this property of Intra-CD as referred to herein
is based upon at least two 5 weight percent portions of
copolymer chain. The Intra-CD of copolymer in accordance
with the present invention can be such that at least two
portions of copolymer chain differ by at least 10 weight
percent ethylene. Differences of at least 20 weight
percent, as well as, of at least 40 weight percent ethylene
are also considered to be in accordance with the present
invention.
The experimental procedure for determining
Intra-CD is as follows. First the Inter-CD is established
as described below, then the polymer chain is broken into
fragments along its contour and the Inter-CD of the
fragments is determined. The difference in the two results
is due to Intra-CD as can be seen in the illustrative
example below.
2015058
- 19 -
Consider a heterogeneous sample polymer containing
monomer units. It consists of 3 molecules designated A,
B, C.
A EEEEPEEEPEEEPPEEPPEPPPEPPPPPPP
B EEEEEPEEEPEEEPPEEEPPPEPPPEEPPP
C EEPEEEPEEEP~ PEEPPPEEPPP
Molecule A is 36.8 wt. % ethylene, B is 46.6%, and
C is 50% ethylene. The average ethylene content for the
mixture is 44.3%. For this sample the Inter-CD is such
that the highest ethylene polymer contains 5.7% more
ethylene than the average while the lowest ethylene content
polymer contains 7.5% less ethylene than the average. Or,
in other words, 100 weight % of the polymer is within +5.7%
and -7.5% ethylene about an average of 44.3%. Accordingly,
the Inter-CD is 7.5% when the given weight % of the polymer
is 100%.
If the chains are broken into fragments, there
will be a new Inter-CD. For simplicity, consider first
breaking only molecule A into fragments shown by the
slashes as follows:
EEEEP/EEEPE/EEPPE/EPPEP/PPEPP/PPPPP
Portions of 72.7%, 72.7%, 50%, 30.8%, 14.3% and 0% ethylene
are obtained. If molecules B and C are similarly broken
and the weight fractions of similar composition are grouped
a new Inter-CD is obtained.
In order to determine the fraction of a polymer
which is intramolecularly heterogeneous in a mixture of .
polymers combined from several sources the mixture must be
separated into fractions which show no further heterogenity
upon subsequent fractionation. These fractions are
subsequently fractured and fractionated to reveal which are
heterogeneous.
- 20 ~
The fragments into which the original polymer is
broken should be large enough to avoid end effects and to
give a reasonable opportunity for the normal statistical
distribution of segments to form over a given monomer
conversion range in the polymerization. Intervals of ca 5
weight % of the polymer are convenient. For example, at an
average polymer molecular weight of about 105, fragments of
ca 5000 molecular weight are appropriate. A detailed
mathematical analysis of plug flow or batch polymerization
indicates that the rate of change of composition along the
polymer chain contour will be most severe at high ethylene
conversion near the end of the polymerization. The
shortest fragments are needed here to show the low ethylene
content sections.
The best available technique for determination of
compositional dispersity for non-polar polymers is
solvent/non-solvent fractionation which is based on the
thermodynamics of phase separation. This technique is
described in "Polymer Fractionation", M. Cantow editor,
Academic 1967, p. 341 and in H. Inagaki, T. Tanaku,
"DeveloPments in Polymer Characterization", 3, 1, (1982).
For non-crystalline copolymers of ethylene and
propylene, molecular weight governs insolubility more than
does composition in a solvent/non-solvent solution. High
molecular weight polymer is less soluble in a given solvent
mix. Also, there is a systematic correlation of molecular
weight with ethylene content for the polymers described
herein. Since ethylene polymerizes much more rapidly than
propylene, high ethylene polymer also tends to be high in .
molecular weight. Additionally, chains rich in ethylene
tend to be less soluble in hydrocarbon/polar non-solvent
mixtures than propylene-rich chains. Furthermore, for
crystalline segments, solubility is significantly reduced.
Thus, the high molecular weight, high ethylene chains are
easily separated on the basis of thermodynamics.
.~ .
~~ - 21 -
A fractionation procedure is as follows:
Unfragmented polymer is dissolved in n-hexane at 23~C to
form ca a 1% solution (1 g. polymer/100 cc hexane).
Isopropyl alcohol is titrated into the solution until
turbidity appears at which time the precipitate is allowed
to settle. The supernatant liquid is removed and the
precipitate is dried by pressing between Mylar~
polyethylene terphthalate) film at 150~C. Ethylene content
is determined by ASTM method D-3900. Titration is resumed
and subsequent fractions are recovered and analyzed until
100% of the polymer is collected. The titrations are
ideally controlled to produce fractions of 5-10% by weight
of the original polymer, especially at the extremes of
composition.
To demonstrate the breadth of the distribution,
the data are plotted as % ethylene versus the cumulative
weight of polymer as defined by the sum of half the weight
% of the fraction of that composition plus the total weight
% of the previously collected fractions.
Another portion of the original polymer is broken
into fragments. A suitable method for doing this is by
thermal degradation according to the following procedure:
In a sealed container in a nitrogen-purged oven, a 2mm
thick layer of the polymer is heated for 60 minutes at
330~C. (The time or temperature can be empirically
adjusted based on the ethylene content and molecular weight~
of the polymer.) This should be adequate to reduce a 105
molecular weight polymer to fragments of ca 5000 molecular
weight. Such degradation does not substantially change the
average ethylene content of the polymer, although propylene
tends to be lost on scission in preference to ethylene.
This polymer is fractionated by the same procedure as the
high molecular weight precursor. Ethylene content is
measured , as well as molecular weight on selected
fractions.
. ~ ,
- ~015Q~
- 22 -
The procedure to characterize intramolecular
heterogeneity is laborious and even when performed at an
absolute optimum, does not show how the segments of the
chain are connected. In fact it is not possible, with
current technology, to determine the polymer structure
without recourse to the synthesis conditions. With
knowledge of the synthesis conditions, the structure can be
defined as follows.
Ethylene, propylene or high alpha-olefin
polymerizations with transition metal catalysts can be
described by the terminal copolymerization model, to an
approximation adequate for the present purpose. (G. Ver
Strate, Encyclopedia of PolYmer Science and Engineering,
vol. 6, 522 (1986)). In this model, the relative
reactivity of the two monomers is specified by two
reactivity ratios defined as follows:
Rl = (rate constant for ethylene adding to ethylene)
(rate constant for propylene adding to ethylene)
R2 = (rate constant for propylene adding to propylene)
(rate constant for ethylene adding to propylene)
Given these two constants, at a given temperature, the
ratio of the molar amount of ethylene, E, to the molar
amount of propylene, P, entering the chain from a solution
containing ethylene and propylene at molar concentrations
[E] and [P] respectively is
E = [E] ~ (R1rE~ + ~Pl) (1)
P = [P] ([E] + R2 [P])
The relation of E and P to the weight % ethylene
in the polymer is as follows
' 20150~8
_
- 23 -
weight % ethylene = E . 100
E + 1.5 P
The values of Rl and R2 are dependent on the
particular comonomer and catalyst employed to prepare the
polymer, the polymerization temperature and, to some
extent, the solvent.
For all transition metal catalysts specified
herein, Rl is significantly larger than R2. Thus, as
can be seen from equation (1), ethylene will be consumed
more rapidly than propylene for a given fraction of the
monomer in the reacting medium. Thus, the ratio of [E]/[P]
will decrease as the monomers are consumed. Only if
Rl=R2 will the composition in the polymer equal that in
the reacting medium.
If the amount of monomer that has reacted at a
given time in a batch reactor or at a given point in a
tubular reactor can be determined, it is possible through
equation (1), to determine the instantaneous composition
being formed at a given point along the polymer chain.
Demonstration of narrow MWD and increasing MW along the
tube proves the compositional distribution is
intramolecular. The amount of polymer formed can be
determined in either of two ways. Samples of the
polymerizing solution may be collected, with appropriate
quenching to terminate the reaction at various points along
the reactor, and the amount of polymer formed evaluated.
Alternatively, if the polymerization is run adiabatically
and the heat of polymerization is known, the amount of
monomer converted may be calculated from the reactor
temperature profile.
Finally, if the average composition of the polymer
is measured at a series of locations along the tube, or at
various times in the batch polymerization case, it is
possible to calculate the instantaneous composition of the
' ' 20150~8
- 24 -
polymer being made. This technique does not require
knowledge of Rl and R2 or the heat of polymerization,
but it does require access to the polymer synthesis step.
All of these methods have been employed with
consistent results.
For the purpose of this patent, Rl and R2 thus
simply serve to characterize the polymer composition in
terms of the polymerization conditions. By defining Rl
and R2, we are able to specify the intramolecular
compositional distribution. In the examples shown below
where VCl4 and ethylaluminum sesquichloride are employed
in hexane as solvent, R1 = 1.8 exp(+500/RTk) and R2 =
3.2 exp(-1500/RTk). Where "R" is the gas constant (1.98
col/deg-mole) and "Tk" is degrees Kelvin. For reference,
at 20~C R1 = 9.7, R2 0.02
The R1 and R2 given above predict the correct
final average polymer composition. If the R1 and R2
and expression (2) are someday proven to be inaccurate the
polymer intramolecular compositional distribution will
remain as defined herein in terms of the polymerization
conditions but may have to be modified on the absolute
composition scales. There is little likelihood that they
are in error by more than a few percent, however.
Ethylene content is measured by ASTM-D3900 for
ethylene-propylene copolymers between 35 and 85 wt.~
ethylene. Above 85~ ASTM-D2238 can be used to obtain
methyl group concentrations which are related to percent
ethylene in an unambiguous manner for ethylene-propylene
copolymers. When comonomers other than propylene are
employed no ASTM tests covering a wide range of ethylene
contents are. available; however, proton and carbon-13
nuclear magnetic reasonance spectroscopy can be employed to
determine the composition of such polymers. These are
absolute techniques requiring no calibration when operated
such that all nucleii of a given element contribute equally
-25-
to the spectra. For ranges not covered by the ASTM tests for
ethylene-propylene copolymers, these nuclear magnetic
resonance methods can also be used.
Molecular weight and molecular weight distribution
are measured using a WatersTM 150C gel permeation
chromatography equipped with a ChromatixTM KMX-6 (LDC-Milton
Roy, Riviera Beach, Florida) on-line light scattering
photometer. The system is used at 135~C with 1,2,4
trichlorobenzene as mobile phase. ShowdexTM (Showa-Denko
America, Inc.) polystyrene gel columns 802, 803, 804 and 805
are used. This technique is discussed in "Liquid
Chromatography of Polymers and Related Materials III",
J. Cazes editor. Marcel Dekker, 1981, p. 207. No corrections
for column spreading are employed; however, data on
generally accepted standards, e.g., National Bureau of
Standards Polyethene 1484 and anionically produced
hydrogenated polyisoprenes (an alternating ethylene-
propylene copolymer) demonstrate that such corrections on
MW/Mn or MZ/Mw are less than .05 unit. MW/Mn is calculated
from an elution time-molecular weight relationship whereas
Mz/Mw is evaluated using the light scattering photometer.
The numerical analyses can be performed using the
commercially available computer software GPC2, MOLWT2
available from LDC/Milton Roy, Riviera Beach, Florida.
As already noted, copolymers in accordance with the
present invention are comprised of ethylene and at least one
other alpha-olefin. It is believed that such alpha-olefins
could include those containing 3 to 18 carbon atoms, e.g.,
propylene, butene-1, pentene-1, etc. Alpha-olefins of 3 to 6
carbons are preferred due to economic considerations. The
most preferred copolymers in accordance with the present
invention are those comprised of ethylene and propylene.
2015058
- - 26 -
As is well known to those skilled in the art,
copolymers of ethylene and higher alpha-olefins such as
propylene often include other polymerizable monomers.
Typical of these other monomers may be non-conjugated
dienes such as the following non-limiting examples:
a. straight chain acyclic dienes such as:
1,4-hexadiene; 1,6-octadiene;
b. branched chain acyclic dienes such as:
5-methyl-1, 4-hexadiene; 3, 7-dimethyl-1,6-octadiene; 3,
7-dimethyl-1,7-octadiene and the mixed isomers of
dihydro-myrcene and dihydroocinene;
c. single ring alicyclic dienes such as: 1,
4-cyclohexadiene; 1,5-cyclooctadiene; and 1,5-
cyclododecadiene;
d. multi-ring alicyclic fused and bridged ring
dienes such as: tetrahydroindene; methyltetrahydroindene;
dicyclopentadiene; bicyclo-(2,2,1)-hepta-2, 5-diene;
alkenyl, alkylidene, cycloalkenyl and cycloalkylidene
norbornenes such as 5-methylene-2-norbornene (MNB),
5-ethylidene-2-norbornene (ENB), 5-propylene-2-norbornene,
5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-nor-
bornene; 5-cyclohexylidene-2-norbornene.
Of the non-conjugated dienes typically used to
prepare these copolymers, dienes containing at least one of
the double bonds in a strained ring are preferred. The
most preferred diene is 5-ethylidene-2-norbornene (ENB).
The amount of diene (wt. basis) in the copolymer could be
from about 0% to 20% with 0% to 15% being preferred. The
most preferred range is 0% to 10%.
As already noted, the most preferred copolymer in
accordance with the present invention is
ethylene-propylene. The average ethylene content of the
copolymer could be as low as about 20% on a weight basis.
The preferred minimum is about 25%. A more preferred
minimum is about 30%. The maximum ethylene content could
2015058
- 27 -
be about 90% on a weight basis. The preferred maximum is
about 85%, with the most preferred being about 80%.
Preferably, the copolymers of this invention intended for
use as viscosity modifier-dispersant contain from about 35
to 75 wt.% ethylene, and more preferably from about 50 to
70 wt.% ethylene.
The molecular weight of copolymer made in
accordance with the present invention can vary over a wide
range. It is believed that the weight-average molecular
weight could be as low as about 2,000. The preferred
minimum is about 10,000. The most preferred minimum is
about 20,000. It is believed that the maximum
weight-average molecular weight could be as high as about
12,000,000. The preferred maximum is about 1,000,000. The
most preferred maximum is about 750,000. An especially
preferred range of weight-average molecular weight for
copolymers intended for use as V.M. polymer is from 50,000
to 500,000.
The copolymers of this invention will also be
generally characterized by a Mooney viscosity (i.e.,
ML(1,+4,) 125~C) of from about 1 to 100, preferably from
about 5 to 70, and more preferably from about 8 to 65, and
by a thickening efficiency ("T.E.") of from about 0.4 to
5.0, preferably from about 1.0 to 4.2, most preferably from
about 1.4 to 3.9.
Another feature of copolymer of the present
invention is that the molecular weight distribution (MWD)
is very narrow, as characterized by at least one of a ratio
of MW/Mn of less than 2 and a ratio of
Mz/Mw of less than 1.8. As relates to
EPM and EPDM, a typical advantage of such copolymers having
narrow MWD is resistance to shear degradation. Particu-
larly for oil additive applications, the preferred copoly-
mers have MW/Mn less than about 1.5, with less than about
1.25 being most preferred. The preferred ~z/~w is less than
2015058
- 28 -
about 1.5, with less than about 1.2 being most preferred.
The copolymers of the instant invention may be
produced by polymerization of a reaction mixture comprised
of catalyst, ethylene and at least one additional
alpha-olefin monomer, wherein the amounts of monomer, and
preferably ethylene, is varied during the course of the
polymerization in a controlled manner as will be
hereinafter described. Solution polymerizations are
preferred.
Any known solvent for the reaction mixture that is
effective for the purpose can be used in conducting
solution polymerizations in accordance with the present
invention. For example, suitable solvents would be
hydrocarbon solvents such as aliphatic, cycloaliphatic and
aromatic hydrocarbon solvents, or halogenated versions of
such solvents. The preferred solvents are C12 or lower,
straight chain or branched chain, saturated hydrocarbons,
C5 to Cg saturated alicyclic or aromatic hydrocarbons
or C2 to C6 halogenated hydrocarbons. Most preferred
are C12 or lower, straight chain or branched chain
hydrocarbons , particularly hexane. Non-limiting
illustrative examples of solvents are butane, pentane,
hexane, heptane, cyclopentane, cyclohexane, cycloheptane,
methyl cyclopentane, methyl cyclohexane, isooctane,
benzene, toluene, xylene, chloroform, chlorobenzenes,
tetrachloroethylene, dichloroethane and trichloroethane.
These polymerizations are carried out in a
mix-free reactor system, which is one in which
substantially no mixing occurs between portions of the
reaction mixture that contain polymer chains initiated at
different times. Suitable reactors are a continuous flow
tubular or a stirred batch reactor. A tubular reactor is
well known and is designed to minimize mixing of the
reactants in the direction of flow. As a result, reactant
concentration will vary along the reactor length. In
201~058
'~ - 29 -
contrast, the reaction mixture in a continuous flow stirred
tank reactor (CFSTR) is blended with the incoming feed to
produce a solution of essentially uniform composition
everywhere in the reactor. Consequently, the growing
chains in a portion of the reaction mixture will have a
variety of ages and thus a single CFSTR is not suitable for
the process of this invention. However, it is well known
that 3 or more stirred tanks in series with all of the
catalyst fed to the first reactor can approximate the
performance of a tubular reactor. Accordingly, such tanks
in series are considered to be in accordance with the
present invention.
A batch reactor is a suitable vessel, preferably
equipped with adequate agitation, to which the catalyst,
solvent, and monomer are added at the start of the
polymerization. The charge of reactants is then left to
polymerize for a time long enough to produce the desired
product or chain segment. For economic reasons, a tubular
reactor is preferred to a batch reactor for carrying out
the processes of this invention.
In addition to the importance of the reactor
system to make copolymers in accordance with the present
invention, the polymerization should be conducted such
that:
(a) the catalyst system produces essentially one
active catalyst species,
(b) the reaction mixture is essentially free of
chain transfer agents, and
(c) the polymer chains are essentially all
initiated simultaneously, which is at the
same time for a batch reactor or at the same
point along the length of the tube for a
tubular reactor.
20150~8
- 30 -
To prepare copolymer structures II and III above
(and, optionally, to prepare copolymer structure I above),
additional solvent and reactants (e.g., at least one of the
ethylene, alpha-olefin and diene) will be added either
along the length of a tubular reactor or during the course
of polymerization in a batch reactor, or to selected stages
of stirred reactors in series in a controlled manner (as
will be hereinafter described) to form the copolymers of
this invention. However, it is necessary to add
essentially all of the catalyst at the inlet of the tube or
at the onset of batch reactor operation to meet the
requirement that essentially all polymer chains are
initiated simultaneously.
Accordingly, polymerization in accordance with the
present invention are carried out:
(a) in at least one mix-free reactor,
(b) using a catalyst system that produces
essentially one active catalyst species,
(c) using at least one reaction mixture which is
essentially transfer agent-free, and
(d) in such a manner and under conditions
sufficient to initiate propagation of
essentially all polymer chains
simultaneously.
Since the tubular reactor is the preferred reactor
system for carrying out polymerizations in accordance with
the present invention, the following illustrative
descriptions are drawn to that system, but will apply to
other reactor systems as will readily occur to the artisan
having the benefit of the present disclosure.
In practicing polymerization processes in
accordance with the present invention, use is preferably
made of at least one tubular reactor. Thus, in its
simplest form, such a process would make use of but a
single, reactor. However, as would readily occur to the
- 31 -
artisan having the benefit of the present disclosure, a
series of reactors could be used with multiple monomer feed
to vary intramolecular composition as described below.
The composition of the catalyst used to produce
alpha-olefin copolymers has a profound effect on copolymer
product properties such as compositional dispersity and
MWD. The catalyst utilized in practicing processes in
accordance with the present invention should be such as to
yield essentially one active catalyst species in the
reaction mixture. More specifically, it should yield one
primary active catalyst species which provides for
substantially all of the polymerization reaction.
Additional active catalyst species could provide as much as
35% (weight) of the total copolymer. Preferably, they
should account for about 10% or less of the copolymer.
Thus, the essentially one active species should provide for
at least 6S% of the total copolymer produced, preferably
for at least 90% thereof. The extent to which a catalyst
species contributes to the polymerization can be readily
determined using the below-described techniques for
characterizing catalyst according to the number of active
catalyst species.
Techniques for characterizing catalyst according
to the number of active catalyst species are within the
skill of the art, as evidenced by an article entitled
"Ethylene-Propylene Copolymers. Reactivity Ratios,
Evaluation and Significance ", C. Cozewith and G. Ver
Strate, Macromolecules, 4, 482 (1971).
It is disclosed by the authors that copolymers
made in a continuous flow stirred reactor should have an
MWD characterized by ~/~n=2 and a narrow
Inter-CD when one active catalyst species is present. By a
combination of fractionation and gel permeation
chromatography (GPC) it is shown that for single active
species catalysts the compositions of the fractions vary no
more than +3% about the average and the MWD (weight- to
,~
- . . 2015058
- 32 -
number-average ratio) for these samples approaches 2. It
is this latter characteristic (Mw/~n ~f
about 2) that is deemed the more important in identifying a
single active catalyst species. On the other hand, other
catalysts gave copolymer with an Inter-CD greater than +10%
about the average and multi-modal MWD often with MW/Mn
greater than 10. These other catalysts are deemed to have
more than one active species.
Catalyst systems to be used in carrying out
processes in accordance with the present invention may be
Ziegler catalysts, which may typically include:
(a) a compound of a transition metal, i.e., a
metal of Groups I-B, III-B, IVB, VB, VIB, VIIB and VIII of
the Periodic Table, and (b) an organometal compound of a
metal of Groups I-A, II-A, II-B and III-A of the Periodic
Table.
The preferred catalyst system in practicing
processes in accordance with the present invention
comprises hydrocarbon-soluble vanadium compound in which
the vanadium valence is 3 to 5 and an organo-aluminum
compound, with the proviso that the catalyst yields
essentially one active catalyst species as described
above. At least one of the vanadium compound/organo-
aluminum pair selected must also contain a valence-bonded
halogen.
In terms of formulas, vanadium compounds useful in
practicing processes in accordance with the present
invention could be:
O ( 1 )
VClx(OR)3-x
where x = 0-3 and R = a hydrocarbon ràdical;
VCl14;
2015058
_ - 33 -
VO(ACAc)2~
where AcAc = acetyl acetonate which may or
may not be alkyl-substituted (e.g.l to C6
alkyl);
V(AcAc)3;
V(dicarbonyl moiety)3;
VOClx(AcAc)3-xl
where x = 1 or 2;
V(dicarbonyl moiety)3Cl; and
VC13.nB,
where n=2-3, B = Lewis base capable of making
hydrocarbon-soluble complexes with VC13, such as
tetrahydrofuran, 2-methyl-tetrahydrofuran and dimethyl
pyridine, and the dicarbonyl moiety is derived from a
dicarbonyl compound of the formula:
R-C-R' C-R
.. ..
O O
In formula (1) above, each R (which can be the
same or different) preferably represents a Cl to C10
aliphatic, alicyclic or aromatic hydrocarbon radical such
as ethyl (Et), phenyl, isopropyl, butyl, propyl, n-butyl,
i-butyl, t-butyl, hexyl, cyclohexyl, octyl, naphthyl, etc.
R, preferably represents an alkylene divalent radical of 1
to 6 carbons (e-g- ' CH2 ~ -C2H4-, etc.).
Nonlimiting illustrative examples of formula (1) compounds
are vanadyl trihalides, alkoxy halides and alkoxides such
as VOC13, VOC12 (OBu) where Bu = butyl, and
VO(OC2Hs)3- The most preferred vanadium compounds
are VC14, VOC13, and VOC12(OR).
As already noted, the co-catalyst is preferably
organo-aluminum compound. In terms of chemical formulas,
these compounds could be as follows:
201~058
- 34 -
AlR3~ Al(OR)R2,
AlR2Cl, R2Al -AlR2,
AlR,RCl, AlR2I,
A12R3C13~ and
AlRC12 ~
where R and R, represent hydrocarbon radicals, the same or
different, as described above with respect to the vanadium
compound formula. The most preferred organo-aluminum
compound is an aluminum alkyl sesquichloride such as
A12Et3C13 or A12(iBu)3cl3.
In terms of performance, a catalyst system
comprised ~f VC14 and A12R3C13, preferably where R
is ethyl, has been shown to be particularly effective. For
best catalyst performance, the molar amounts of catalyst
components added to the reaction mixture should provide a
molar ratio of aluminum/vanadium (Al/V) of at least about
2. The preferred minimum Al/V is about 4. The maximum
Al/V is based primarily on the considerations of catalyst
expense and the desire to minimize the amount of chain
transfer that may be caused by the organo-aluminum compound
(as explained in detail below). Since, as is known certain
organo-aluminum compounds act as chain transfer agents, if
too much is present in the reaction mixture the
/~n Of the copolymer may rise above 2.
Based on these considerations, the maximum Al/V could be
about 25, however, a maximum of about 17 is more
preferred. The most preferred maximum is about 15.
With reference again to processes for making
copolymer in accordance with the present invention, it is
well known that certain combinations of vanadium and
aluminum compounds that can comprise the catalyst system
can cause branching and gelation during the polymerization
for polymers containing high levels of diene. To prevent
this from happening Lewis bases such as ammonia, tetra-
hydrofuran, pyridine, tributylamine, tetrahydrothiophene,
' 20150~8
~ - 35 -
etc., can be added to the polymerization system using
techniques well known to those skilled in the art.
Chain transfer agents for the Ziegler-catalyzed
polymerization of alpha-olefins are well known and are
illustrated, by way of example, by hydrogen or diethyl zinc
for the production of EPM and EPDM. Such agents are very
commonly used to control the molecular weight of EPM and
EPDM produced in continuous flow stirred reactors. For the
essentially single active species Ziegler catalyst systems
used in accordance with the present invention, addition of
chain transfer agents to a CFSTR reduces the polymer
molecular weight but does not affect the molecular weight
distribution. On the other hand, chain transfer reactions
during tubular reactor polymerization in accordance with
the present invention broaden polymer molecular weight
distribution and Inter-CD. Thus the presence of chain
transfer agents in the reaction mixture should be minimized
or omitted altogether. Although difficult to generalize
for all possible reactions, the amount of chain transfer
agent used should be limited to those amounts that provide
copolymer product in accordance with the desired limits as
regards MWD and compositional dispersity. It is believed
that the maximum amount of chain transfer agent present in
the reaction mixture could be as high as about 0.2 mol/mol
of transition metal, e.g., vanadium, again provided that
the resulting copolymer product is in accordance with the
desired limits as regards MWD and compositional
dispersity. Even in the absence of added chain transfer
agent, chain transfer reactions can occur because propylene
and the organo-aluminum cocatalyst can also act as chain
transfer agents. In general, among the organo-aluminum
compounds that in combination with the vanadium compound
yield just one active species, the organo-aluminum compound
that gives the highest copolymer molecular weight at
acceptable catalyst activity should be chosen. Furthermore,
if the Al/V ratio has an effect on the molecular weight of
' 20150~
- 36 -
copolymer product, that Al/V should be used which gives the
highest molecular weight also at acceptable catalyst
activity. Chain transfer with propylene can best be
limited by avoiding excessively elevated temperature during
the polymerization as described below.
Molecular weight distribution and Inter-CD are
also broadened by catalyst deactivation during the course
of the polymerization which leads to termination of growing
chains. It is well known that the vanadium-based Ziegler
catalysts used in accordance with the present invention are
subject to such deactivation reactions which depend to an
extent upon the composition of the catalyst. Although the
relationship between active catalyst lifetime and catalyst
system composition is not known at present, for any given
catalyst, deactivation can be reduced by using the shortest
residence time and lowest temperature in the reactor that
will produce the desired monomer conversions.
Polymerizations in accordance with the present
invention should be conducted in such a manner and under
conditions sufficient to initiate propagation of
essentially all copolymer chains simultaneously. This can
be accomplished by utilizing the process steps and
conditions described below.
The catalyst components are preferably premixed,
that is, reacted to form active catalyst outside of the
reactor, to ensure rapid chain initiation. Aging of the
premixed catalyst system, that is, the time spent by the
catalyst components (e.g., vanadium compound and
organo-aluminum) in each other's presence outside of the
reactor, should preferably be kept within limits. If not
aged for a sufficient period of time, the components will
not have reacted with each other sufficiently to yield an
adequate quantity of active catalyst species, with the
result of nonsimultaneous chain initiation. Also, it is
known that the activity of the catalyst species will
decrease with time so that the aging must be kept below a
20150~8
.
- 37 -
maximum limit. It is believed that the minimum aging
period, depending on such factors as concentration of
catalyst components, temperature and mixing equipment,
could be as low as about 0.1 second. The preferred minimum
aging period is about 0.5 second, while the most preferred
minimum aging period is about 1 second. While the maximum
aging period could be higher, for the preferred
vanadium/organo-aluminum catalyst system the preferred
maximum is about 200 seconds. A more preferred maximum is
about 100 seconds. The most preferred maximum aging period
is about 50 seconds. The premixing could be performed at
low temperature such as 40~C or below. It is preferred
that the premixing be performed at 25~C or below, with 20~C
or below being most preferred.
Preferably, the catalyst components are premixed
in the presence of the selected polymerization diluent or
solvent under rapid mixing conditions, e.g., at impingement
Reynolds Numbers (NRE) of at least 10,000, more preferably
at least 50,000, and most preferably at least 100,000.
Impingement Reynolds number is defined as
NRE = DN J
where N is fluid flow velocity (cm./sec.), D is inside tube
diameter (cm), ~ is fluid density (g./cm.3) and ~cis
fluid viscosity (poise).
The temperature of the reaction mixture should
also be kept within certain limits. The temperature at the
reactor inlets should be high enough to provide complete,
rapid chain initiation at the start of the polymerization
reaction. The length of time the reaction mixture spends
at high temperature must be short enough to minimize the
amount of undesirable chain transfer and catalyst
deactivation reactions.
201~0~8
_ - 38 -
Temperature control of the reaction mixture is
complicated somewhat by the fact that the polymerization
reaction generates large quantities of heat. This problem
is, preferably, taken care of by using prechilled feed to
the reactor to absorb the heat of polymerization. With
this technique, the reactor is operated adiabatically and
the temperature is allowed to increase during the course of
polymerization. As an alternative to feed prechill, heat
can be removed from the reaction mixture, for example, by a
heat exchanger surrounding at least a portion of the
reactor or by well-known autorefrigeration techniques in
the case of batch reactors or multiple stirred reactors in
series.
If adiabatic reactor operation is used, the inlet
temperature of the reactor feed could be about from -50~C
to 150~C. It is believed that the outlet temperature of
the reaction mixture could be as high as about 200~C. The
preferred maximum outlet temperature is about 70~C The
most preferred maximum is about 60~C. In the absence of
reactor cooling, such as by a cooling jacket, to remove the
heat of polymerization, it has been determined (for a
mid-range ethylene content EP copolymer and a solvent with
heat capacity similar to hexane) that the temperature of
the reaction mixture will increase from reactor inlet to
outlet by about 13~C per weight percent of copolymer in the
reaction mixture (weight of copolymer per weight of
solvent).
Having the benefit of the above disclosure, it
would be well within the skill of the art to determine the
operating temperature conditions for making copolymer in
accordance with the present invention. For example, assume
an adiabatic reactor and an outlet temperature of 35~C are
desired for a reaction mixture containing 5% copolymer.
The reaction mixture will increase in temperature by about
13~C for each weight percent copolymer or 5 wt% x 13~C/wt.%
= 65~C. To maintain an outlet temperature of 35~C, it will
2015058
_ - 39 -
thus require a feed that has been prechilled to 35~C-65~C =
-30~C. In the instance that external cooling is used to
absorb the heat of polymerization, the feed inlet
temperature could be higher with the other temperature
constraints described above otherwise being applicable.
Because of heat removal and reactor temperature
limitations, the preferred maximum copolymer concentration
at the reactor outlet is 25 wt./100 wt. diluent. The most
preferred maximum concentration is 15 wt/100 wt. There is
no lower limit to concentration due to reactor operability,
but for economic reasons it is preferred to have a
copolymer concentration of at least 2 wt/100 wt. Most
preferred is a concentration of at least 3 wt/100 wt.
The rate of flow of the reaction mixture through
the reactor should be high enough to provide good mixing of
the reactants in the radial direction and minimize mixing
in the axial direction. Good radial mixing is beneficial
not only to both the Intra- and Inter-CD of the copolymer
chains but also to minimize radial temperature gradients
due to the heat generated by the polymerization reaction.
Radial temperature gradients in the case of multiple
segment polymers will tend to broaden the molecular weight
distribution of the copolymer since the polymerization rate
is faster in the high temperature regions resulting from
poor heat dissipation. The artisan will recognize that
achievement of these objectives is difficult in the case of
highly viscous solutions. This problem can be overcome to
some extent through the use of radial mixing devices such
as static mixers (e.g., those produced by the Kenics
Corporation).
It is believed that residence time of the reaction
mixture in the mix-free reactor can vary over a wide
range. It is believed that the minimum could be as low as
about 0.2 second. A preferred minimum is about 0.5
second. The most preferred minimum is about 1 second. It
is believed that the maximum could be as high as about 3600
- 40 -
'~ _
seconds. A preferred maximum is about 40 seconds. The
most preferred maximum is about 20 seconds.
Preferably, the fluid flow of the polymerization
reaction mass through the tubular reactor will be under
turbulent conditions, e.g., at a flow Reynolds Number (NR)
of at least 10,000, more preferably at least 50,000, and
most preferably at least 100,000 (e.g., 150,000 to
250,000), to provide the desired radial mixing of the fluid
in the reactor. Flow Reynolds Number is defined as
NR = D'N'/
wherein N' is fluid flow velocity (cm./sec.), D, is inside
tube diameter of the reactor (cm.), ~ is fluid density
(g./cm.3) and ~ is fluid viscosity (poise).
If desired, catalyst activators for the selected
vanadium catalysts can be used as long as they do not cause
the criteria for a mix-free reactor to be violated,
typically in amounts up to 20 mol %, generally up to 5
mol%, based on the vanadium catalyst, e.g., butyl
perchlorocrotonate, benzoyl chloride, and other activators
disclosed in U.S. Patent Nos. 4,808,387, issued February 28,
1989, and 4,871,523, issued October 3, 1989, and filed
May 15, 1987. Other useful catalyst activators include
esters of halogenated organic acids, particularly alkyl
trichloroacetates, alkyl tribromoacetates, esters of
ethylene glycol monoalkyl (particularly monoethyl) ethers
with trichloroacetic acid and alkyl perchlorocrotonates, and
acyl halides. Specific examples of these compounds include
benzoyl chloride, methyl trichloroacetate, ethyl
trichloroacetate, methyl tribromoacetate, ethyl
tribromoacetate, ethylene glycol monoethyl ether
trichloroacetate, ethylene glycol monoethyl ether
tribromoacetate, butyl perchlorocrotonate and methyl
perchlorocrotonate.
.: .
2015058
~_ - 41 -
By practicing processes in accordance with the
present invention, alpha-olefin copolymers having very
narrow MWD can be made by direct polymerization. Although
narrow MWD copolymers can be made using other known
techniques, such as by fractionation or mechanical
degradation, these techniques are considered to be
impractical to the extent of being unsuitable for
commercial-scale operation. As regards EPM and EPDM made
in accordance with the present invention, the products have
good shear stability and (with specific intramolecular CD)
excellent low temperature properties which make them
especially suitable for lube oil applications.
It is preferred that the Intra-CD of the copolymer
is such that at least two portions of an individual
intramolecularly heterogeneous chain, each portion
comprising at least 5 weight percent of said chain, differ
in composition from one another by at least 5 weight
percent ethylene. The Intra-CD can be such that at least
two portions of copolymer chain differ by at least 10
weight percent ethylene. Differences of at least 20 weight
percent, as well as, 40 weight percent ethylene are also
considered to be in accordance with the present invention.
It is also preferred that the Inter-CD of the
copolymer is such that 95 wt.% of the copolymer chains have
an ethylene composition that differs from the copolymer
average weight percent ethylene composition by 15 wt.% or
less. The preferred Inter-CD is about 13% or less, with
the most preferred being about 10% or less.
The particularly preferred copolymers of this
invention are those that have a weight average molecular
weight of from about 20,000 to about 250,000.
Grafting Materials
The materials or compounds that are grafted on the
ethylene copolymer backbone to form the grafted ethylene
copolymers of the instant invention are generally those
materials that can be grafted onto said ethylene copolymers
20150~8
-
- 42 -
to form the grafted ethylene copolymers, which grafted
copolymers are then reacted with the amido-amines or with
the carboxylic acid components and amido-amines to form the
nitrogen containing grafted ethylene copolymers of the
instant invention. These materials preferably contain
olefinic unsaturation and further preferably contain at
least one of carboxylic acid moiety, ester moiety, or
anhydride moiety. The olefinically unsaturated portion,
i.e., ethylenically unsaturated portion, is one which is
capable of reacting with the ethylene copolymer backbone,
and upon reaction therewith becomes saturated.
These materials are generally well known in the
art as grafting materials and are generally commercially
available or may be readily prepared by well known
conventional methods.
The preferred grafting materials are the
carboxylic acid materials. The carboxylic acid material
which is grafted to or reacted with the ethylene copolymer
to form the grafted ethylene copolymer is preferably
ethylenically unsaturated, preferably monounsaturated,
carboxylic acid material and can be either a monocarboxylic
or dicarboxylic acid material. The dicarboxylic acid
materials include (1) monounsaturated c4 to C10
dicarboxylic acid wherein (a) the carboxyl groups are
vicinyl, i.e., located on adjacent carbon atoms, and (b) at
least one, preferably both, of said adjacent carbon atoms
are part of said monounsaturation; and (2) derivatives of
(1) such as anhydrides or C1 to C5 alcohol derived
mono- or diesters of (1). Upon reaction with the ethylene
copolymer the monounsaturation of the dicarboxylic acid,
anhydride, or ester becomes saturated. Thus, for example,
maleic anhydride becomes an ethylene copolymer substituted
succinic anhydride.
The monocarboxylic acid materials include (1)
monounsaturated C3 to C10 monocarboxylic acid wherein
the carbon-carbon bond is conjugated to the carboxy group,
i.e., of the structure
~ - 43 -
l 11
- C = C - C - ; and
(2) derivatives of (l) such as Cl to CS alcohol derived
monoesters of (l). Upon reaction with the ethylene
copolymer, the monounsaturation of the monounsaturated
carboxylic acid material becomes saturated. Thus, for
example, acrylic acid becomes an ethylene copolymer
substituted propionic acid, and methacrylic acid beçomes an
ethylene copolymer substituted isobutyric acid.
Exemplary of such unsaturated mono- and
dicarboxylic acids, or anhydrides and thereof include
fumaric acid, itaconic acid, maleic acid, maleic anhydride,
chloromaleic anhydride, acrylic acid, methacrylic acid,
crotonic acid, cinnamic acid, methyl acrylate, ethyl
acrylate, methyl methacrylate, etc.
Preferred carboxylic acid materiaLs are the
dicarboxylic acid anhydrides. Maleic anhydride or a
derivative thereof is particularly preferred as it does not
appear to homopolymerize appreciably but grafts onto the
ethylene copolymer to give two carboxylic acid
functionalities. Such preferred materials have the generic
formula
R' R''
I
C C
o=C C=O
O
wherein R' and R" are independently hydrogen or a halogen.
Additionally, as taught by U.S. Patent Nos.
4,160,739 and 4,161,452, various unsaturated comonomers may
be grafted on the ethylene copolymer together with the
unsaturated carboxylic acid material. Such graft monomer
systems may comprise one or a mixture of comonomers
' 2015~58
different from said unsaturated carboxylic acid material,
and which contain only one copolymerizable double bond and
are copolymerizable with said unsaturated acid component.
Typically, such comonomers do not contain free
carboxylic acid groups and are esters containing alpha-
ethylenic unsaturation in the acid or alcohol portion;
hydrocarbons, both aliphatic and aromatic, containing ,
alpha-ethylenic unsaturation, such as the C4-C12 alpha
olefins, for example hexene, nonene, dodecene, etc.;
styrenes, for example styrene, alpha-methyl styrene,
p-methyl styrene, butyl styrene, etc.; and vinyl monomers,
for example vinyl acetate, vinyl chloride, vinyl ketones
such as methyl and ethyl vinyl ketone, and nitrogen
containing vinyl monomer such as v'inyl pyridine and vinyl
pyrrolidine, etc. Comonomers containing functional groups
which may cause crosslinking, gelation or other interfering
reactions should be avoided, although minor amounts of such
comonomers (up to about 10% by weight of the comonomer
system) often can be tolerated.
Specific useful copolymerizable comonomers include
the following:
(A) Esters of saturated acids and unsaturated
alcohols wherein the saturated acids may be monobasic or
polybasic acids containing up to about 40 carbon atoms such
as the following: acetic, propionic, butyric, valeric,
caproic, stearic, oxalic, malonic, succinic, glutaric,
adipic, pimelic, suberic, azelaic, sebacic, phthalic,
isophthalic, terephthalic, hemimellitic, trimellitic,
trimesic and the like, including mixtures. The unsaturated
alcohols may be monohydroxy or polyhydroxy alcohols and may
contain up to about 40 carbon atoms, such as the
following: allyl, methallyl, crotyl, l-chloroallyl,
2-chloroallyl, cinnamyl, vinyl, methyl vinyl, l-phenallyl,
butenyl, propargyl, l-cyclohexene-3-ol, oleyl, and the
like, including mixtures.
20150~8
_ - 45 -
(B) Esters of unsaturated monocarboxylic acids
containing up to about 12 carbon atoms such as acrylic,
methacrylic and crotonic acid, and an esterifying agent
containing up to about 50 carbon atoms, selected from
saturated alcohols and alcohol epoxides. The saturated
alcohols may preferably contain up to about 40 carbon atoms
and include monohydroxy compounds such as: methanol,
ethanol, propanol, butanol, 2-ethylhexanol, octanol,
dodecanol, cyclohexanol, cyclopentanol, neopentyl alcohol,
and benzyl alcohol; and alcohol ethers such as the mono-
methyl or monobutyl ethers of ethylene or propylene glycol,
and the like, including mixtures. The alcohol epoxides
include fatty alcohol epoxides, glycidol, and various
derivatives of alkylene oxides, epichlorohydrin, and the
like, including mixtures.
The components of the graft copolymerizable system
are used in a ratio of unsaturated carboxylic acid material
monomer component to comonomer component of about 1:4 to
4:1, preferably about 12 to 2:1 by weight.
Grafting of the Ethylene Copolymer
Grafting of the ethylene copolymer with the
grafting material may be conducted by either conventional
grafting processes or by a process which does not
substantially adversely affect (substantially broaden) the
narrow MWD of the ethylene copolymer, e.g., relatively low
temperature and/or low shear process. While not wishing to
be bound by any theory, it is believed that the reaction of
the polyamine containing at least two reactive amino groups
to form the nitrogen containing grafted ethylene copolymer
or with the polyol to form the ester containing grafted
ethylene copolymer produces a product having a broader
molecular weight distribution than that of the ethylene
copolymer. Thus, even if the grafted ethylene copolymer is
produced by a process which does not substantially broaden
the MWD, the reaction of this narrow MWD grafted ethylene
copolymer with the polyamine containing at least two
201~05~
- 46 -
reactive amino groups or with the polyol with result in a
product having a broadened MWD.
In the grafting process which does not
substantially adversely affect or broaden the narrow MWD of
the ethylene copolymer the grafting conditions,
particularly temperature, are such that the narrow MWD as
defined herein of the ethylene copolymer reactant is not
substantially adversely affected, i.e., is not
substantially broadened. For the purposes of this
application the MWD is considered to be substantially
broadened if the difference in MWD between the ungrafted
ethylene-alpha-olefin copolymer and the grafted
ethylene-alpha-olefin copolymer is greater than about 10~.
That is to say the grafting conditions are those which are
effective to yield a graft copolymer which contains an
ethylene copolymer backbone having substantially the same
of similar MWD distribution as the ethylene copolymer
reactant. By substantially the same or similar MWD is
meant a MWD which is about 10% or less different from the
MWD of the ungrafted ethylene-alpha-olefin copolymer, i.e.,
the difference between the MWD of ungrafted
ethylene-alpha-olefin copolymer and grafted
ethylene-alpha-olefin copolymer is about 10% or less. If a
high shear and/or high temperature grafting method such as
extruder grafting is utilized the narrow MWD, as defined
hereinafore, of the ethylene copolymer is substantially
adversely affected, i.e., is substantially broadened. That
is to say the resultant grafted ethylene copolymer no
longer has the narrow MWD of the ungrafted ethylene
copolymer.
Generally, the grafting conditions used to graft
the grafting material, e.g., maleic anhydride, onto the
ethylene-alpha-olefin copolymer depend, to a degree, upon
the MWD of the ungrafted ethylene-alpha-olefin copolymer
reactant. In general, the narrower the MWD of the
ungrafted copolymer reactant the milder the grafting
20150~8
- 47 -
conditions, i.e., temperature and/or shear, that are
utilized to produce a grafted ethylene-alpha-olefin
copolymer having a MWD which-differs 10~ or less from the
MWD of the ungrafted ethylene-alpha-olefin copolymer
reactant. Thus, with ungrafted ethylene-alpha-olefin
copolymers having broader MWD, harsher grafting conditions,
i.e., higher temperatures and/or greater shear, can be used
than with ungrafted copolymers having a lower MWD to
produce grafted ethylene-alpha-olefin copolymers having a
MWD which differs, e.g., is higher, from the MWD of the
ungrafted ethylene-alpha-olefin copolymer reactant by no
more than about 10%. Generally, grafting is carried out in
solution, preferably using free-radical initiators, at
temperatures below about 225~C, preferably below about
200~C, more preferably below about 190~C, and most
preferably below about 180~C in order to produce a grafted
copolymer having this narrow MWD. Higher temperatures will
result in a grafted polymer which generally no longer has
the substantially narrow MWD of the ethylene copolymer
reactant as described herein.
The conventional grafting of the ethylene
copolymer with the grafting material such as carboxylic
acid material may be by any suitable and well-known
conventional method such as thermally by the "ene"
reaction, using copolymers containing unsaturation, such as
ethylene-propylene-diene polymers either chlorinated or
unchlorinated, or more preferably it is by free-radical
induced grafting in solvent, preferably in a mineral
lubricating oil as solvent.
The radical grafting is preferably carried out
using free radical initiators such as peroxides,
hydroperoxides, and azo compounds and preferably those
which have a boiling point greater than about 100~C. and
which decompose thermally within the grafting temperature
range to provide said free radicals. The initiator is
generally used at a level of between about 0.005~ and about
2015058
- 48 -
1%, based on the total weight of the polymer solution, and
temperatures of about 150~ to 250~C, preferably from about
150~C to about 220~C are used.
The ethylenically unsaturated carboxylic acid
material, such as maleic anhydride, will be generally used
in an amount ranging from about 0.01% to about 10%,
preferably 0.1 to 2.0%, based on weight of the initial
total solution. The aforesaid carboxylic acid material and
free radical initiator are generally used in a weight
percent ratio range of 1.0:1 to 30:1, preferably 3.0:1 to
6:1.
In the practice of the instant invention when
these ethylenically unsaturated grafting materials are
grafted onto the aforedescribed ethylene copolymer the
resultant grafted copolymer contains the residue of the
ethylene copolymer as the backbone and the residue of the
ethylenically unsaturated grafting material as the grafted
moiety. By residues is meant the respective moieties
produced by and remaining after the grafting process or
reaction. Thus, for example, while the ethylenically
unsaturated grafting material may be maleic anhydride,
after the grafting reaction it is the succinic anhydride
moiety that is grafted or attached to the ethylene
copolymer backbone. Thus, this succinic anhydride moiety
is referred to herein as the residue of the ethylenically
unsaturated grafting material, i.e., residue of maleic
anhydride.
A preferred method of grafting is by free-radical
induced grafting in solvent, preferably in a mineral
lubricating oil as solvent. The free-radical grafting is
preferably carried out using free radical initiators such
as peroxides, hydroperoxides, and azo compounds and
preferably those which have a boiling point greater than
about 100~C and which decompose thermally within the
grafting temperature range to provide said free radicals.
Representative of these free-radical initiators are
' . . 20150~8
_ - 49 -
asobutyro-nitrile, 2,5-di-methyl-hex-3-yne-2, 5
bis-tertiary-butyl peroxide (sold as Lupersol 130) or its
hexane analogue, di-tertiary butyl peroxide and dicumyl
peroxide. The initiator is generally used at a level of
between about 0.005% and about 1%, based on the toal weight
of the polymer solution, and temperatures of about 150 to
220~C.
The initiator grafting is preferably carried out
in an inert atmosphere, such as that obtained by nitrogen
blanketing. While the grafting can be carried out in the
presence of air, the yield of the desired graft polymer is
generally thereby decreased as compared to grafting under
an inert atmosphere substantially free of oxygen. The
grafting time will usually range from about 0.1 to 12
hours, preferably from about 0.5 to 6 hours, more prefer-
ably 0.5 to 3 hours. The graft reaction will be usually
carried out to at least approximately 4 times, preferably
at least about 6 times the half-life of the free-radical
initiator at the reaction temperature employed, e.g. with
2,5-dimethyl hex-3-yne-2, 5-bis(t-butyl peroxide) 2 hours
at 160~C. and one hour at 170~C., etc.
In the grafting process, usually the copolymer
solution is first heated to grafting temperature and
thereafter said grafting material such as unsaturated
carboxylic acid material and initiator are added with
agitation, although they could have been added prior to
heating. When the reaction is complete, the excess
grafting material can be eliminated by an inert gas purge,
e.g. nitrogen sparging. Preferably the grafting material
such as carboxylic acid material that is added is kept
below its solubility limit in the polymer solution, e.g.
below about 1 wt. %, preferably below 0.4 wt. % or less, of
free maleic anhydride based on the total weight of
polymer-solvent solution, e.g. ethylene copolymer mineral
lubricating oil solution. Continuous or periodic addition
of the grafting material such as carboxylic acid material
20150~8
- 50 -
along with an appropriate portion of initiator, during the
course of the reaction, can be utilized to maintain the
grafting material such as carboxylic acid material below
its solubility limits, while still obtaining the desired
degree of total grafting.
In the initiator grafting step the maleic
anhydride or other carboxylic acid material used will be
grafted onto both the polymer and the solvent for the
reaction. Many solvents such as dichlorobenzene are rela-
tively inert and may be only slightly grafted, while
mineral oil will tend to be more grafted. The exact split
of graft between the substrate present depends upon the
polymer and its reactivity, the reactivity and type of oil,
the concentration of the polymer in the oil, and also upon
the maintenance of the carboxylic acid material in solution
during the course of the reaction and minimizing the
presence of dispersed, but undissolved acid, e.g. the
maleic anhydride. The undissolved acid material appears to
have an increased tendency to react to form oil insoluble
materials as opposed to dissolved acid material. The split
between grafted oil and grafted polymer may be measured
empirically from the infrared analyses of the product
dialyzed into oil and polymer fractions.
The grafting is preferably carried out in a
mineral lubricating oil which need not be removed after the
grafting step but can be used as the solvent in the
subsequent reaction of the graft polymer with the polyamine
or polyol and as a solvent for the end product to form the
lubricating additive concentrate.
The solution grafting step when carried out in the
presence of a high temperature decomposable peroxide can be
accomplished without substantial degradation of the chain
length (molecular weight) of the ethylene containing
polymer. This can be an advantage as opposed to high
2015058
- 51 -
temperature thermal reactions which depend on degradation
to apparently form free radical reactive sites. Measure-
ment of molecular weights and degradation can be evaluated
by determination of the thickening efficiency (T.E.) of the
polymer as will later be described.
The amount of grafting material such as carboxylic
acid material used in the grafting reaction is an amount
which is effective to provide a grafted ethylene copolymer
which upon further reaction with the polyamine as described
hereinafter provides a material exhibiting the properties
of a multifunctional viscosity index improver additive,
more specifically a viscosity index improver-dispersant
additive, i.e., a material having both V.I. improving and
dispersancy properties in an oleaginous composition. That
is to say, an amount which is effective to provide, upon
reaction of the grafted ethylene copolymer with the
polyamine, an oleaginous composition exhibiting improved
viscometric and dispersancy properties. Generally, this
amount of grafting material, e.g., moles of carboxylic acid
material such as maleic anhydride, is an amount which is
effective to provide a grafted ethylene copolymer, e.g.,
ethylene-alpha-olefin substituted carboxylic acid material
such as ethylene- propylene substituted succinic anhydride,
containing an average number of acid material moieties,
e.g., succinic anhydride, grafted to or present on a 10,000
number average molecular weight segment of a mole of
ethylene copolymer of at least about 0.1, preferably at
least about 0.5, and more preferably at least about 1. The
maximum average number of grafted moieties present per
10,000 average number molecular weight segment of a mole of
ethylene copolymer backbone should not exceed about 10,
preferably about 7 and more preferably about 5.
Preferably, the average number, moles, of grafted moieties
present per mole of ethylene copolymer backbone is at least
about 0.6, preferably at least about 0.8, and more
preferably at least about 1. Preferably, the maximum
~ 2015058
- 52 -
average number of grafted moieties grafted to or present
per mole of ethylene copolymer backbone should generally
not exceed about 10, preferably about 7, and more
-preferably about 5. Thus, for example, a mole of grafted
ethylene copolymer, e.g., ethylene- propylene substituted
succinic anhydride, containing an ethylene copolymer
backbone such as an ethylene- propylene backbone having an
average number molecular weight of 50,000 contains grafted
to said backbone an average number of succinic anhydride
moieties of from about 0.5 to about 50, preferably from
about 0.6 to about 10. Typically, from about 0.2 to about
12, preferably from about 0.4 to about 6 moles of said
carboxylic acid material are charged to the reactor per
mole of ethylene copolymer charged.
Normally, not all of the ethylene copolymer reacts
with the carboxylic acid material, e.g., maleic anhydride,
to produce a grafted ethylene copolymer, e.g.,
ethylene-propylene substituted succinic anhydride. The
resultant reaction product mixture, therefore, contains
reacted or grafted ethylene copolymer, e.g.,
ethylene-propylene substituted succinic anhydride,
unreacted or ungrafted ethylene copolymer, and unreacted
grafting material, e.g., maleic anhydride. The unreacted
ethylene copolymer is typically not removed from the
reaction product mixture, and the reaction product mixture,
generally stripped of any unreacted grafting material, is
utilized as is or is employed for further reaction with the
amine as described hereinafter.
Characterization of the average number of moles of
grafting material such as carboxylic acid material, e.g.,
maleic anhydride, which have reacted per mole of ethylene
copolymer charged to the reaction (whether it has undergone
reaction or not) is defined herein as the average number of
grafted moieties grafted to or present per mole of ethylene
copolymer the resulting reaction product mixture can be
subsequently modified, i.e., increased or decreased by
201~0~8
- 53 -
techniques known in the art, such modifications do not
alter the average number of grafted moieties as defined
above. The term grafted ethylene copolymer is intended to
refer to the reaction product mixture whether it has
undergone such modification or not.
The grafted, preferably acid material grafted,
ethylene copolymer is reacted with a polyamine or polyol to
form the nitrogen or ester containing grafted ethylene
copolymers of the instant invention. When the grafted
ethylene copolymer is reacted with a polyamine the
resultant product is a nitrogen containing grafted ethylene
copolymer.
Polyamine
The polyamines containing one primary amino group
and at least one secondary amino group are typically those
that contain one primary amino group and from 1 to about 6
secondary amino groups. Preferably these polyamines
contain no tertiary amino groups. These polyamines may
also optionally contain an oxygen or sulfur atom. The
amino groups, and the oxygen or sulfur if present, are
separated from each other by hydrocarbylene groups,
preferably alkylene groups, more preferably alkylene groups
containing from 1 to about 6 carbon atoms.
These polyamines contain from 2 to about 7
nitrogens, from 7 (8 if an oxygen or sulfur is present) to
about 80 carbons, and optionally a sulfur or oxygen atom.
These polyamines include polyamines represented by the
formula
H2N (R1-NH)Z (R2-A )y R3 (I)
wherein:
Rl is a hydrocarbylene group containing from 1
to about 6 carbons;
2~150~8
_ - 54 -
R2 is a hydrocarbylene group containing from 1
to about 6 carbons;
R3 is a hydrocarbyl group containing from 1 to
about 40 carbons, preferably from 5 to about 30 carbons,
and more preferably from about 10 to about 20 carbons;
z has a value of from 1 to 6, preferably 1 to 5,
and more preferably 1 to 4;
y is zero or one; and
A is oxygen or sulfur.
Preferred hydrocarbyl radicals represented by R3
are the aliphatic hydrocarbyl radicals, either saturated or
unsaturated. The preferred aliphatic hydrocarbyl radicals
are the acyclic aliphatic hydrocarbyl radicals, either
saturated or unsaturated, straight chain or branched. The
preferred aliphatic acyclic hydrocarbyl radicals are the
alkyl radicals, either straight chain or branched, with the
straight chain or slightly branched alkyl radicals being
preferred.
Thus, R3 is most preferably an alkyl radical
containing from 1 to about 40 carbons, preferably from 5 to
about 30 carbons, and more preferably from about 10 to
about 20 carbons. Preferred alkyl radicals are the
straight chain or slightly branched alkyl radicals.
Preferred hydrocarbylene radicals represented by
Rl and R2 are the aliphatic hydrocarbylene radicals.
Preferred aliphatic hydrocarbylene radicals are the acyclic
aliphatic hydrocarbylene radicals. Of these, the alkylene
radicals are preferred. The preferred alkylene radicals
are those containing 2 to 4 carbon atoms. The most
preferred alkylene radical is propylene.
The polyamines of the instant invention may
contain an oxygen or a sulfur atom, i.e., they may be
polyamine ethers or thioethers. In such case, y in
Formula I is one and these polyamine ethers or thioethers
may be represented by the formula
20150~8
- 55 -
H2N--~Rl-NH~ R2-A-R3 (Ia)
wherein Rl, R2, R3, A and z are as defined.
Alternatively, the oxygen or sulfur atoms may be
absent, and the polyamines contain only nitrogen, carbon
and hydrogen atoms. In such case y in Formula I is O and
these polyamines may be represented by the formula
H2N-~Rl-NH~ R3 (Ib)
These polyamines, including the polyamine ethers
and thioethers, are known compounds which may be readily
prepared by conventional methods. Some of these compounds
are commercially available.
Some illustrative non-limiting examples of
compounds of Formula Ib include:
H2N CH2cH2cH2NHcH2cH2cH2NHcH2cH2cH3
H2N-cH2cH2cH2NHcH2cH2cH2NHcH2(cH2)IscH3;
H2N-CH2CH2-NH-CH2CH3;
H2Nt CH2CH2CH2-NH ~CH2(CH2)8CH3;
H2Nt-CH2CH2CH2-NH~ CH2(CH2)5CH3;
H2N~CH2CH2-NHt~CH2 (CH2) 18CH3
H2Nt-CH2CH2CH2NH~ CH2t-CH2 ~oCH3;
H2Nt-CH2CH2CH2NH~ CH2t CH2)12 CH3;
H2Nt-CH2CH2CH2NH~ CH2t CH2)14 CH3;
H2Nt--CH2CH2CH2NH~ CH2t-CH2 ~5 3
H2Nt-CH2CH2CH2NH~ CH2t-CH2 ~ 6CH3;
H2Nt-CH2CH2CH2NH~ CH2-~CH2)18 CH3; a
H2NtCH2CH2CH2NH~ CH2~CH2) 20-CH3
. ~ 20150~8
Some illustrative non-limiting examples of
compounds of Formula Ia include:
2 H2CH2CH2NHCH2CH2CH2NHCH2CH2CH2-o-CH2CH2CH3;
2 -t H2CH2CH2NH~ CH2cH2cH2-s-cH2cH2cH2cH3;
H2Nt CH2CH2NH~ CH2CH2CH2-0-CH2CH2CH2CH2CH3;
H2Nt-CH2CH2CH2NH~ CH2CH2CH2-0-CH2--tCH2)10 CH3; and
2N~ CH2CH2CH2NH~ CH2CH2-S-CH2CH3.
It is to be generally understood that mixtures of
two or more different polyamines, as well as individual
polyamines, may be used in the present invention.
It is preferable to employ mixtures of two or more
different polyamines, particularly mixtures of polyamines
wherein the only difference between the polyamines lies in
R3 being a different alkyl. Such a mixture, for example,
may contain 5 different polyamines of Formula Ib wherein
R1 is propylene, z is 3, and R3 is respectively
dodecyl, tetradecyl, hexadecyl, heptadecyl, and octadecyl.
Such polyamines are referred to as tallow amines and are
generally commercially available.
201~0~8
- 57 -
-
REACTION OF GRAFTED ETHYLENE
COPOLYMER WITH POLYAMINE
The grafted high molecular weight ethylene
copolymer, preferably in solution, such as an oil solution,
containing 5 to 95 wt.%, preferably 5 to 30 wt. %, and more
preferably 10 to 20 wt.% of said grafted ethylene
copolymer, is readily reacted with the polyamine by
introducing the polyamine into said grafted ethylene
copolymer containing solution and heating at a temperature
of from about 100~C to 250~C, preferably from 125 to 175~C,
for from about 1 to 10 hours, usually about 2 to about 6
hours. The heating is preferably carried out, in the case
of ethylene copolymer substituted dicarboxylic acid
material, to favor formation of imides or mixtures of
imides and amides rather than amides and salts. In the
case of ethylene copolymer substituted monocarboxylic acid
material heating is preferably carried out to favor
formation of amides rather than salts. Removal of water
assures completion of the imidation/ amidation reaction.
Reaction ratios can vary considerably, depending upon the
reactants, amounts of excess, type of bonds formed, etc.
Generally, from about 1 to 5, preferably from about 1.5 to
3 moles of ethylene copolymer substituted monocarboxylic or
dicarboxylic acid moiety content, e.g., grafted succinic
anhydride content, is used per equivalent of polyamine
reactant, e.g., primary amine.
Preferably, the ethylene copolymer substituted
mono- or dicarboxylic acid material and polyamines are
contacted for a time and under conditions sufficient to
react substantially the primary nitrogen in the polyamine
reactant. The progress of this reaction can be followed by
infra-red analysis.
20150S8
- 58 -
This reaction can be conducted in a polar or
non-polar solvent, e.g., xylene, toluene, benzene, and the
like, and is preferably conducted in the presence of a
mineral or synthetic lubricating oil.
In aspect B of the instant invention the
carboxylic acid material grafted ethylene copolymer, e.g.,
succinic anhydride grafted ethylene-propylene copolymer, is
reacted with the polyamine containing one primary amino
group and at least one secondary amino group and a
carboxylic acid component which is described more fully
hereinafter. In the reaction involving the carboxylic acid
material grafted ethylene copolymer, polyamine, and
carboxylic acid component it is generally preferred that a
reaction mixture containing said carboxylic acid material
grafted ethylene copolymer and said carboxylic acid
component be first prepared. This reaction mixture can be
readily prepared by admixing the carboxylic acid component
and the carboxylic acid material grafted ethylene
copolymer. Into this reaction mixture is then introduced
the polyamine. The polyamine is then reacted with the
carboxylic acid material grafted ethylene copolymer and
with the carboxylic acid component to form the nitrogen
containing carboxylic acid material grafted ethylene
copolymer of the instant invention.
Alternatively, the polyamine and the carboxylic
acid component can be added substantially simultaneously or
concurrently to the carboxylic acid material grafted
ethylene-propylene copolymer to form a reaction mixture.
This reaction mixture is then reacted under conditions
effective for the three components to react and form the
nitrogen containing carboxylic acid material grafted
ethylene copolymer of the instant invention.
Furthermore, the carboxylic acid component and the
polyamine may be prereacted, and this prereacted carboxylic
acid component/polyamine may then be coreacted with the
carboxylic acid material grafted ethylene copolymer to form
the nitrogen containing carboxylic acid material grafted
ethylene copolymer of the instant invention.
2015058
_ - 59 -
CarboxYlic Acid Component
The carboxylic acid component includes:
hydrocarbyl substituted dicarboxylic acid or anhydride,
preferably succinic anhydride or acid, having 12 to 49
carbons, preferably 16 to 49 carbons in said hydrocarbyl
group; long chain monocarboxylic acid of the formula
RlOCOOH where R10 is a hydrocarbyl group of 50 to 400
carbons and long chain hydrocarbyl substituted dicarboxylic
acid or anhydride, preferably succinic anhydride or acid,
having from about 50 to about 400 carbons in said hydro-
carbyl group. The preferred carboxylic acid component is
the long chain hydrocarbyl substituted dicarboxylic acid or
anhydride, preferably succinic acid or anhydride, having
from about 50 to about 400 carbon atoms in said hydrocarbyl
group. Said hydrocarbyl groups are essentially aliphatic
and include alkenyl and alkyl groups. The longer chain
acids and anhydrides are preferred, particularly when the
grafting reaction is carried out in lubricating oil.
The about C50-C400 hydrocarbyl subtituted
dicarboxylic acid or anhydride includes the reaction
product of the C50-C400 hydrocarbon polymer, generally
a polyolefin, with (i) monounsaturated C4 to C10
dicarboxylic acid wherein (a) the carboxyl groups are
vicinyl, i.e., located on adjacent carbon atoms, and (b) at
least one, preferably both, of said adjacent carbon atoms
are part of said monounsaturation; or with (ii) derivatives
of (i) such as anhydrides of (i). Upon reaction with the
hydrocarbon polymer, the monounsaturation of the
dicarboxylic acid, anhydride, etc. becomes saturated. Thus
for example, maleic anhydride becomes a hydrocarbyl
substituted succinic anhydride.
Typically, from about 0.7 to about 4.0 (e.g., 0.8
to 2.6), preferably from about 1.0 to about 2.0, and most
preferably from about 1.1 to about 1.7 moles of said
unsaturated C4 to C10 dicarboxylic acid, anhydride or
2015058
- 60 -
_
ester are charged to the reactor per mole of polyolefin
charged.
Normally, not all of the polyolefin reacts with
the unsaturated acid or derivative and the hydrocarbyl
substituted dicarboxylic acid material will contain
unreacted polyolefin. The unreacted polyolefin is
typically not removed from the reaction mixture (because
such removal is difficult and would be commercially
infeasible) and the product mixture, stripped of any
unreacted monounsaturated C4 to C10 dicarboxylic acid
or anhydride, is employed as the carboxylic acid component.
Characterization of the average number of moles of
dicarboxylic acid or anhydride, which have reacted per mole
of polyolefin charged to the reaction (whether it has
undergone reaction or not) is defined herein as
functionality. Said functionality is based upon (i)
determination of the saponification number of the resulting
product mixture using potassium hydroxide; and (ii) the
number average molecular weight of the polymer charged,
using techniques well known in the art. Functionality is
defined solely with reference to the resulting product
mixture. Although the amount of said reacted polyolefin
contained in the resulting product mixture can be
subsequently modified, i.e., increased or decreased by
techniques known in the art, such modifications do not
alter functionality as defined above. The term
C50-C400 hydrocarbyl substituted dicarboxylic acid
material is intended to refer to the product mixture
whether it has undergone such modification or not.
Accordingly, the functionality of the C50-C400
hydrocarbyl substituted dicarboxylic acid material will be
typically at least about 0.5, preferably at least about
0.8, and most preferably at least about 0.9 and will vary
typically from about 0.5 to about 2.8 (e.g., 0.6 to 2),
preferably from about 0.8 to about 1.4, and most preferably
from about 0.9 to about 1.3.
2015058
- 61 -
_
Exemplary of such unsaturated dicarboxylic acids
or anhydrides thereof are fumaric acid, itaconic acid,
maleic acid, maleic anhydride, chloromaleic acid,
chloromaleic anhydride, etc.
Preferred about C50 to about C400 olefin
polymers for reaction with the unsaturated dicarboxylic
acids or derivatives thereof are polymers comprising a
major molar amount of C2 to C10, e.g., C2 to C5
monoolefin. Such olefins include ethylene, propylene,
butylene, isobutylene, pentene, octene-1, styrene, etc.
The polymers can be homoOolymers such as polyisobutylene,
as well as copolymers of two or more of such olefins such
as copolymers of: ethylene and propylene; butylene and
isobutylene; propylene and isobutylene: etc. Other
copolymers include those in which a minor molar amount of
the copolymer monomers, e.g., 1 to 10 mole %, is a C4 to
C18 non-conjugated diolefin, e.g., a copolymer of
isobutylene and butadiene; or a copolymer of ethylene,
propylene and 1,4-hexadiene; etc.
In some cases, the olefin polymer may be
completely saturated, for example an ethylene-propylene
copolymer made by a Ziegler-Natta synthesis usig hydrogen
as a moderator to control molecular weight.
The olefin polymers used will usually have number
average molecular weights within the range of about 700 and
about 5,600, more usually between about 800 and about
3000. Particularly useful olefin polymers have number
average molecular weights within the range of about 900 and
about 2500 with approximately one terminal double bond per
polymer chain. An especially useful starting material is
polyisobutylene. The number average molecular weight for
such polymers can be determined by several known
techniques. A convenient method for such determination is
by gel permeation chromatography (GPC) which additionally
provides molecular weight distribution information, see
2015058
- 62 -
W. W. Yau, J. J. Kirkland and D. D. Bly, "Modern Size
Exclusion Liquid Chromatography", John WIley and Sons, New
York, 1979.
Processes for reacting the about C50 to about
C400 olefin polymer with the C4_10 u'nsaturated
dicarboxylic acid or anhydride are known in the art. For
example, the olefin polymer and the dicarboxylic acid or
derivative may be simply heated together as disclosed in
U.S. Patents 3,361,673 and 3,401,118 to cause a thermal
"ene" reaction to take place. Or, the olefin polymer can
be first halogenated, for example, chlorinated or
brominated to about 1 to 8 wt. %, preferably 3 to 7 wt. %
chlorine, or bromine, based on the weight of polymer, by
passing the chlorine or bromine through the polyolefin at a
temperature of 60 to 250~C, e.g. 120 to 160~C, for about
0.5 to 10, preferably 1 to 7 hours. The halogenated
polymer may then be reacted with sufficient unsaturated
acid or derivative at 100 to 250~C, usually about 180 to
235~C, for about 0.5 to 10, e.g. 3 to 8 hours, so the
product obtained will contain the desired number of moles
of the unsaturated acid or derivative per mole of the
halogenated polymer. Processes of this general type are
taught in U.S. Patents 3,087,936; 3,172,892; 3,272,746 and
others.
Alternatively, the olefin polymer, and the
unsaturated acid or derivative are mixed and heated while
adding chlorine to the hot material. Processes of this
type are disclosed in U.S. Patents 3,215,707; 3,231,587;
3,912,764; 4,110,349; and in U.K. 1,550,219.
By the use of halogen, about 65 to 95 wt. ~ of the
polyolefin, e.g. polyisobutylene will normally reacted with
the dicarboxylic acid or derivative. Upon carrying out a
thermal reaction without the use of halogen or a catalyst,
then usually only about 50 to 75 wt. % of the polyiso-
butylene will react. Chlorination helps increased the
reactivity.
- 63 - 20~ ~ 05
Particularly preferred as the acid component is
polyisobutenyl succinic anhydride.
PRE-REACTED POLYAMINE-
CARBOXYLIC ACID COMPONENT
The aforesaid polyamine and carboxylic acid
component may be pre-reacted, with the acid being generally
attached to the polyamine through salt, imide, amide, or
other linkages so that a primary or secondary amine group
of the polyamine is still available for reaction with the
acid moieties of the grafted high molecular weight ethylene
copolymer.
The carboxylic acid material grafted ethylene
copolymer is reacted with the polyamine containing one
primary amino group and one or more secondary amino groups
and carboxylic acid component or pre-reacted
polyamine/carboxylic acid component substantially as
described hereinafore for the reaction of the carboxylic
acid material grafted ethylene copolymer with the
polyamine. Thus, for example a reaction mixture containing
the grafted ethylene copolymer, e.g., ethylene-propylene
substituted succinic anhydride, and carboxylic acid
component, e.g., polyisobutenyl substituted succinic
anhydride, is prepared by admixing these two reactants, and
the polyamine is then introduced into this reaction mixture
and the reaction is carried out as described hereinafore.
Alternatively, the carboxylic acid component and polyamine
may be added substantially simultaneously to a reaction
mixture containing the carboxylic acid material grafted
ethylene copolymer.
Generally, the amount of the carboxylic acid
component utilized is an amount sufficient to provide about
0.5 to about 4, preferably from about 1 to about 2 moles of
said carboxylic acid component per molar amount of the
carboxylic acid moieties present in the grafted ethylene
copolymer. For example, with a grafted ethylene-propylene
copolymer of about 40,000 ~n and averaging 4
2015058
- 64 -
-
succinic anhydride groups per molecule, about 4 moles of
polyisobutenyl succinic anhydride would preferably be used
per mole of grafted copolymer. Generally, from about 1 to
5, preferably from about 1.5 to 3 moles of the combined
carboxylic acid moiety content of the grafted ethylene
copolymer and the carboxylic acid content are used per
equivalent of amido-amine reactant, e.g., amine.
Under certain conditions, particularly upon
storage, oleaginous compositions, particularly oil
concentrates, containing the multifunctional viscosity
index improver additives of the instant invention may
exhibit an increase in viscosity. This viscosity increase
appears to be due, at least in part, to chain extension
and/or cross-linking of the nitrogen containing grafted
ethylene copolymer of the instant invention. In order to
stabilize the viscosity and retard or inhibit said
viscosity increase of these oil compositions the nitrogen
containing grafted ethylene copolymers of the instant
invention can be treated or post-reacted with a variety of
materials, particularly acid materials, to inactivate the
reactive amino groups, i.e., secondary amino groups or
primary amino groups. This treatment prevents, diminishes,
or retards chain-extension and/or crosslinking of the
nitrogen containing grafted ethylene copolymer. Thus, for
example, the nitrogen containing acid material grafted
ethylene copolymer may be reacted or post-treated with C1
~ C30 monocarboxylic acids or anhydrides, preferably
acetic
- 65 -
anhydride, or unsubstituted or C1 to C28 hydrocarbyl
substituted dicarboxylic acid anhydrides as aisclosed in
U.S. Patent No. 4,137,185; the sulfonic acids of U.S. Patent
No. 4,144,181; and the C12 to C18 hydrocarbyl substituted
dicarboxylic anhydrides, preferably C12 to C18 hydrocarbyl
substituted succinic anhydride, of U.S. Patent No.
4,803,003.
Preferred viscosity stabilizing materials are
those disclosed in U.S. Patent No. 4,803,003, i.e., the
C12 to about C18 hydrocarbyl substituted dicarboxylic
anhydrides. These anhydrides may be represented by the
general formula R11Y wherein Rll is a hydrocarbyl group
containing a total of from 12 to about 18, preferably 12 to
16, more preferably 12 to 14, and most preferably 12
carbons, which are essentially aliphatic, saturated or
unsaturated, and include alkenyl groups, alkyl groups, and
mixtures of alkenyl groups and alkyl groups, preferably
alkenyl groups, and can be straight chain or branched, and
Y is a dicarboxylic anhydride moiety. When R11 is an
alkenyl group it is preferred that the olefinic
unsaturation site be located near the anhydride, e.g.,
allylic to Y, moiety. The radical Y will usually contain 4
to 10, preferably 4 to 8, more preferably 4 to 6, and most
preferably 4 carbon atoms and will define a dicarboxylic
anhydride. The Y radical may be represented by the formula--
\ /
O = C -- Z -- C = O
wherein Z is selected from alkylene and alkenylene radicalscontaining from 2 to 8, preferably 2 to 6, more preferably
2 to 4, and most preferably 2 carbon atoms. Preferably Z
is an alkylene radical. The most preferred Y radical is
the succinic anhydride radical, i.e.,
'' ~
201~058
- 66 -
-
H C C - H
O C C - O
o
The Y radical is linked to the R11 group by a carbon to
carbon linkage.
The amount of the hydrocarbyl substituted
dicarboxylic anhydride utilized is a viscosity stabilizing
effective amount. By viscosity stabilizing effective
amount is meant any amount which is effective to stabilize
the viscosity of an oleaginous solution of the nitrogen
containing acid material grafted ethylene copolymers, i.e.,
inhibit or retard the increase in viscosity over an
extended period of time of an oil solution, particularly an
oil concentrate, of the nitrogen containing grafted
ethylene copolymers. Generally this amount is from about
0.5 - 2.5, preferably 1 - 1.5 moles of C12 to about C18
hydrocarbyl substituted dicarboxylic anhydride per mole of
any remaining primary or secondary amino groups of the
ethylene copolymer grafted with a carboxylic acid material
and thereafter reacted with the amido-amine.
The chain extension termination or end-capping of
the nitrogen containing grafted ethylene copolymer which
was preferentially prepared in a mineral oil solution can
be conducted by subsequently introducing the C12 to about
C18 hydrocarbyl substituted dicarboxylic anhydride
directly into the reaction system used to prepare said
nitrogen containing grafted ethylene copolymer, or it can
be a separate non-integrated reaction step. Generally, the
nitrogen containing carboxylic acid material grafted
ethylene copolymer is first produced by preparing the
grafted ethylene copolymer and then reacting this grafted
copolymer with at least one polyamine, or with the
- 67 - 201S0~8
carboxylic acid component and polyamine, or with the
preformed carboxylic acid component and polyamine, and this
nitrogen containing grafted ethylene copolymer is then
subsequently reacted or treated with the C12 to about
C18 hydrocarbyl substituted dicarboxylic anhydride in a
end-capping or chain extension limiting step. A viscosity
stabilizing effective amount of the C12 to about C18
hydrocarbyl substituted dicarboxylic anhydride is
introduced into the heated solution containing the nitrogen
or ester containing grafted ethylene copolymer and the
reaction carried on for a period of about 0.25 to 8 hours
at a temperature of about 100~ to 200~C being preferred.
In order to fully complete the reaction, it is generally
useful to utilize a slight excess, i.e., about 1 to 30,
more usually about 1 to 10, percent by weight of the C12
to about C18 hydrocarbyl substituted dicarboxylic
anhydride. The entire reaction is generally carried out
under an inert atmosphere, for example, a nitrogen blanket.
This reaction can be conducted in a polar or
non-polar solvent, e.g., xylene, toluene, benzene, and the
like, and is preferably conducted in the presence of a
mineral or synthetic lubricating oil.
Alternatively, at least a portion of the C12 to
C18 hydrocarbyl substituted dicarboxylic anhydride or
other end-capping agent can be introduced into a reaction
mixture containing the carboxylic acid material grafted
ethylene copolymer prior to or concurrently with the
introduction of the polyamine reactant, and the remaining
portion of the end-capping agent can be reacted with the
preformed, partially end-capped nitrogen containing grafted
ethylene copolymer.
The nitrogen containing grafted ethylene
copolymers, i.e., the derivatized ethylene copolymers, of
the instant invention, either unreacted or reacted with the
viscosity stabilizing or end-capping agents described
hereinafore, may optionally be post-treated by contacting
- 68 -
said nitrogen containing acid material grafted ethylene
copolymer with one or more post-treating reagents selected
from the group consisting of boron oxide, boron oxide
hydrate, boron halides, boron acids, esters of boron acids,
carbon disulfide, sulfur, sulfur chlorides, alkenyl
cyanides, aldehydes, ketones, urea, thio-urea, guanidine,
dicyanodiamide, hydrocarbyl phosphates, hydrocarbyl
phosphites, hydrocarbyl thiophosphates, hydrocarbyl
thiophosphites, phosphorus sulfides, phosphorus oxides,
phosphoric acid, hydrocarbyl thiocyanates, hydrocarbyl
isocyanates, hydrocarbyl isothiocyantes, epoxides,
episulfides, formaldehyde or formaldehyde-producing
compounds plus phenols, and sulfur plus phenols.
Since post-treating processes involving the use of
these post-treating reagents are known insofar as
application to reaction products of high molecular weight
carboxylic acid acylating agents of the prior disclosures
and amines and/or alcohols, detailed descriptions of these
processes herein is unnecessary. In order to apply these
processes to the compositions of this invention, all that
is necessary is that reaction conditions, ratio of
reactants, and the like as described in these prior
disclosure processes, be applied to the novel compositions
of this invention. The following U.S. patents disclose
post-treating processes and post-treating reagents
applicable to the compositions of this invention:
U.S. Pat. Nos. 3,087,936; 3,200,107; 3,254,025; 3,256,185;
3,278,550; 3,281,428; 3,282,955; 3,284,410; 3,338,832,
3,344,069; 3,366,569; 3,373,111; 3,367,943; 3,403,102;
3,428,561; 3,502,677; 3,513,093; 3,533,945; 3,541,012 (use
of acidified clays in post-treating carboxylic derivative
compositions derived from the acrylating reagents of this
invention and amines); 3,639,242; 3,708,522; 3,859,318;
3,865,813; 3,470,098; 3,369,021; 3,184,411; 3,185,645;
~_ - 69 - 20~5~5~
3,245,908; 3,245,90g; 3,245,910; 3,573,205; 3,692,681;
3,749,695; 3,865,740; 3,954,639; 3,458,530; 3,390,086;
3,367,943; 3,185,704, 3,551,466; 3,415,~50; 3,312,619;
3,280,034; 3,718,663; 3,652,616; UK Pat. No. 1,085,903; UK
Pat. N0. 1,162,436; U.S. Pat. No. 3,558,743. The processes
of these patents, as applied to the compositions of this
invention, and the post-treated compositions thus produced
constitute a further aspect of this invention.
A minor amount, e.g. 0.01 up to 49 wt %,
preferably 0.05 to 25 wt. %, based on the weight of the
total composition, of the V.I. improver-dispersants
produced in accordance with this invention can be
incorporated into a major amount of an oleaginous material,
such as a lubricating oil or hydrocarbon fuel, depending
upon whether one is forming finished products or additive
concentrates. When used in lubricating oil compositions,
e.g. automotive or diesel crankcase lubricating oil,
derivatized copolymer concentrations are usually within the
range of about 0.01 to 25 wt %, of the total composition.
The lubricating oils to which the products of this
invention can be added include not only hydrocarbon oil
derived from petroleum, but also include synthetic
lubricating oils such as esters of dibasic acids; complex
esters made by esterifications of monobasic acids,
polyglycols, dibasic acids and alcohols; polyolefin oils,
etc.
The nitrogen containing acid material grafted
ethylene copolymer of the invention may be utilized in a
concentrate form, e.g., from about 5 wt % up to about 49
wt. %, preferably 7 to 25 wt. %, in oil, e.g., mineral
lubricating oil, for ease of handling, and may be prepared
in this form by carrying out the reaction of the invention
in oil as previously discussed.
The above oil compositions may optionally contain
other conventional additives, pour point depressants,
2015058
- 70 -
~,_
antiwear agents, antioxidants, other viscosity-index
improvers, dispersants, corrosion inhibitors, anti-foaming
agents, detergents, rust inhibitors, friction modifiers,
and the like.
Corrosion inhibitors, also known as anti-corrosive
agents, reduce the degradation of the metallic parts
contacted by the lubricating oil composition. Illustrative
of corrosion inhibitors are phosphosulfurized hydrocarbons
and the products obtained by reaction of a
phosphosulfurized hydrocarbon with an alkaline earth metal
oxide or hydroxide, preferably in the presence of an
alkylated phenol or of an alkylphenol thioester, and also
preferably in the presence of carbon dioxide.
Phosphosulfurized hydrocarbons are prepared by reacting a
suitable hydrocarbon such as a terpene, a heavy petroleum
fraction of a C2 to C6 olefin polymer such as
polyisobutylene, with from 5 to 30 wt. % of a sulfide of
phosphorus for 1/2 to 15 hours, at a temperature in the
range of about 66 to about 316. C. Neutralization of the
phosphosulfurized hydrocarbon may be effected in the manner
taught in U.S. Patent No. 1,969,324.
Oxidation inhibitors, or antioxidants, reduce the
tendency of mineral oils to deteriorate in service which
deterioration can be evidenced by the products of oxidation
such as sludge and varnish-like deposits on the metal
surfaces, and by viscosity growth. Such oxidation
inhibitors include alkaline earth metal salts of
alkylphenolthioesters having preferably C5 to C12 alkyl
side chains, e.g., calcium nonylphenol sulfide, barium
toctylphenyl sulfide, dioctylphenylamine,
phenylalphanaphthylamine, phospho- sulfurized or sulfurized
hydrocarbons, etc.
Other oxidation inhibitors or antioxidants useful
in this invention comprise oil-soluble copper compounds.
The copper may be blended into the oil as any suitable
~ 71 ~ 2015058
oil-soluble copper compound. By oil soluble it is meant
that the compound is oil soluble under normal blending
conditions in the oil or additive package. The copper
compound may be in the cuprous or cupric form. The copper
may be in the form of the copper dihydrocarbyl thio- or
dithio-phosphates. Alternatively, the copper may be added
as the copper salt of a synthetic or natural carboxylic
acid. Examples of same thus include C10 to C18 fatty
acids, such as stearic or palmitic acid, but unsaturated
acids such as oleic or branched carboxylic acids such as
napthenic acids of molecular weights of from about 200 to
500, or synthetic carboxylic acids, are preferred, because
of the improved handling and solubility properties of the
resulting copper carboxylates. Also useful are oil-soluble
copper dithiocarbamates of the general formula (RR,NCSS)nCu
(where n is 1 or 2 and R and R, are the same or different
hydrocarbyl radicals containing from 1 to 18, and
preferably 2 to 12, carbon atoms, and including radicals
such as alkyl, alkenyl, aryl, aralkyl, alkaryl and
cycloaliphatic radicals. Particularly preferred as R and
R, groups are alkyl groups of from 2 to 8 carbon atoms.
Thus, the radicals may, for example, be ethyl, n-propyl,
i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl,
i-hexyl, n-heptyl, n-octyl, decyl, dodecyl, octadecyl,
2-ethylhexyl, phenyl, butylphenyl, cyclohexyl,
methylcyclopentyl, propenyl, butenyl, etc. In order to
obtain oil solubility, the total number of carbon atoms
(i.e., R and R,) will generally be about 5 or greater.
Copper sulphonates, phenates, and acetylacetonates may also
be used.
Exemplary of useful copper compounds are copper
CuI and/or CuII salts of alkenyl succinic acids or
anhydrides. The salts themselves may be basic, neutral or
acidic. They may be formed by reacting (a) polyalkylene
succinimides (having polymer groups of ~n of 700
' 2015058
- 72 -
;~. ....
to 5,000) derived from polyalkylene-polyamines, which have
at least one free carboxylic acid group, with (b) a
reactive metal compound. Suitable reactive metal compounds
include those such as cupric or cuprous hydroxides, oxides,
acetates, borates, and carbonates or basic copper
carbonate.
Examples of these metal salts are Cu salts of
polyisobutenyl succinic anhydride, and Cu salts of
polyisobutenyl succinic acid. Preferably, the selected
metal employed is its divalent form, e.g., Cu+2. The
preferred substrates are polyalkenyl succinic acids in
which the alkenyl group has a molecular weight greater than
about 700. The alkenyl group desirably has a Mn from
about 900 to 1,400, and up to 2,500, with a ~n of about
950 being most preferred. Especially preferred is
polyisobutylene succinic anhydride or acid. These
materials may desirably be dissolved in a solvent, such as
a mineral oil, and heated in the presence of a water
solution (or slurry) of the metal bearing material.
Heating may take place between 70. and about 200~C.
Temperatures of 110~C to 140~C are entirely adequate. It
may be necessary, depending upon the salt produced, not to
allow the reaction to remain at a temperature above about
140~C for an extended period of time, e.g., longer than 5
hours, or decomposition of the salt may occur.
The copper antioxidants (e.g., Cu-polyisobutenyl
succinic anhydride, Cu-oleate, or mixtures thereof) will be
generally employed in an amount of from about 50 to 500 ppm
by weight of the metal, in the final lubricating or fuel
composition.
Friction modifiers serve to impart the proper
friction characteristics to lubricating oil compositions
such as automatic transmission fluids.
Representative examples of suitable friction
modifiers are found in U.S. Patent No. 3,933,659 which
discloses fatty acid esters and amides; U.S. Patent No.
- 73 -
4,176,074 which describes molybdenum complexes of
polyisobutenyl succinic anhydride-amino alkanols; U.S.
Patent No. 4,105,571 which discloses gl~cerol esters of
dimerized fatty acids; U.S. Patent No. 3,779,928 which
discloses alkane phosphonic acid salts; U.S. Patent No.
3,778,375 which discloses reaction products of a
phosphonate with an oleamide; U.S. Patent No. 3,852,205
which discloses S-carboxyalkylene hydrocarbyl succinimide,
S-carboxyalkylene hydrocarbyl succinamic acid and mixtures
thereof; U.S. Patent No. 3,879,306 which discloses
N(hydroxyalkyl)alkenyl-succinamic acids or succinimides;
U.S. Patent No. 3,932,290 which discloses reaction
products of di- (lower alkyl) phosphites and epoxides; and
U.S. Patent No. 4,028,258 which discloses the alkylene
oxide adduct of phosphosulfurized N-(hydroxyalkyl) alkenyl
succinimides. The most preferred friction modifiers are
succinate esters, or metal salts thereof, of hydrocarbyl
substituted succinic acids or anhydrides and thiobis-
alkanols such as described in U.S. Patent No. 4,344,853.
Dispersants maintain oil insolubles, resulting
from oxidation- during use, in suspension in the fluid thus
preventing sludge flocculation and precipitation or
deposition on metal parts. Suitable dispersants include
high molecular weight alkyl succinimides, the reaction
product of oil-soluble polyisobutylene succinic anhydride
with ethylene amines such as tetraethylene pentamine and
borated salts thereof.
Pour point depressants, otherwise known as lube
oil flow improvers, lower the temperature at which the
fluid will flow or can be poured. Such additives are well
known. Typically of those additives which usefully
optimize the low temperature fluidity of the fluid are
C8-C18 dialkylfumarate vinyl acetate copolymers,
~~ - 74 -
polymethacrylates, and wax naphthalene. Foam control can
be provided by an antifoamant of the polysiloxane type,
e.g., silicone oil and polydimethyl siloxane.
Anti-wear agents, as their name implies, reduce
wear of metal parts. Representatives of conventional
antiwear agents are zinc dialkyldithiophosphate and zinc
diaryldithiosphate.
Detergents and metal rust inhibitors include the
metal salts of sulphonic acids, alkyl phenols, sulfurized
alkyl phenols, alkyl salicylates, naphthenates and other
oil soluble mono- and dicarboxylic acids. Highly basic
(viz, overbased) metal sales, such as highly basic alkaline
earth metal sulfonates (especially Ca and Mg salts) are
frequently used as detergents. Representative examples of
such materials, and their methods of preparation, are found
in Canadian Serial No. 512,917, filed July 2, 1986, now
Patent No. 1,262,721, issued November 7, 1989.
Some of these numerous additives can provide a
multiplicity of effects, e.g., a dispersant-oxidation
inhibitor. This approach is well known and need not be
further elaborated herein.
Compositions when containing these conventional
additives are typically blended into the base oil in
amounts which are effective to provide their normal
attendant function. Representative effective amounts of
such additives are illustrated as follows:
Additive Wt.% a.i. Wt. ~ a.i.
(Broad) (Preferred)
Viscosity Modifier .01-12 .01-4
Corrosion Inhibitor 0.01-5 .01-1.5
Oxidation Inhibitor 0.01-5 .01-1.5
~,
_ 75 _ 20150~8
-
Additive Wt.% a.i. Wt. ~ a.i.
(Broad) (Preferred)
Dispersant 0.1-20 0.1-8
Pour Point Depressant 0.01-5 .01-1.5
Anti-Foaming Agents 0.001-3 .001-0.15
Anti-Wear Agents 0.001-5 .001-1.5
Friction Modifiers 0.01-5 .01-1.5
Detergents/Rust Inhibitors .01-10 .01-3
Mineral Oil Base Balance Balance
When other additives are employed, it may be
desirable, although not necessary, to prepare additive
concentrates comprising concentrated solutions or
dispersions of the dispersant (in concentrate amounts
hereinabove described), together with one or more of said
other additives (said concentrate when constituting an
additive mixture being referred to here in as an additive
package) whereby several additives can be added
simultaneously to the base oil to form the lubricating oil
composition. Dissolution of the additive concentrate into
the lubricating oil may be facilitated by solvents and by
mixing accompanied with mild heating, but this is not
essential. The concentrate or additive-package will
typically be formulated to contain the dispersant additive
and optional additional additives in proper amounts to
provide the desired concentration in the final formulation
when the additive-package is combined with a predetermined
amount of base lubricant. Thus, the products of the
- 76 - 2015058
-
present invention can be added to small amounts of base oil
or other compatible solvents along with other desirable
additives to form additive-packages containing active
ingredients in collective amounts of typically from about
2.5 to about 90%, and preferably from about 5 to about 75%,
and most preferably from about 8 to about 50% by weight
additives in the appropriate proportions with the remainder
being base oil.
The final formulations may employ typically about
wt. % of the additive-package with the remainder being
base oil.
All of said weight percents expressed herein are
based on active ingredient (a.i.) content of the additive,
and/or upon the total weight of any additive-package, or
formulation which will be the sum of the a.i. weight of
each additive plus the weight of total oil or diluent.
As mentioned hereinafore, the nitrogen containing
acid material grafted ethylene copolymers of the present
invention are particularly useful as fuel and lubricating
oil additives.
The nitrogen containing grafted ethylene
copolymers of this invention find their primary utility,
however, in lubricating oil compositions, which employ a
base oil in which these copolymers are dissolved or
dispersed.
Thus, base oils suitable for use in preparing the
lubricating compositions of the present invention include
those conventionally employed as crankcase lubricating oils
for spark-ignited and compression-ignited internal
combustion engines, such as automobile and truck engines,
marine and railroad diesel engines, and the like.
Advantageous results are also achieved by employing the
additives of the present invention in base oils
conventionally employed in and/or adapted for use as power
transmitting fluids such as automatic transmission fluids,
tractor fluids, universal tractor fluids and hydraulic
_ 77 _ 201~058
fluids, heavy duty hydraulic fluids, power steering fluids
and the like. Gear lubricants, industrial oils, pump oils
and other lubricating oil compositions can also benefit
from the incorporation therein of the additives of the
present invention.
Thus, the additives of the present invention may
be suitably incorporated into synthetic base oils such as
alkyl esters of dicarboxylic acids, polyglycols and
alcohols; polyalpha-olefins, polybutenes, alkyl benzenes,
organic esters of phosphoric acids, polysilicone oils, etc.
The nitrogen containing carboxylic acid material
grafted ethylene copolymers of the instant invention are
oil-soluble, dissolvable in oil with the aid of a suitable
solvent, or are stably dispersible therein. The terms
oil-soluble, dissolvable in oil, or stably dispersible in
oil as that terminology is used herein does not necessarily
indicate that the materials are soluble, dissolvable,
miscible, or capable of being suspended in oil in all
proportions. It does mean, however, that the additives for
instance, are soluble or stably dispersible in oil to an
extent sufficient to exert their intended effect in the
environment in which the oil is employed. Moreover, the
additional incorporation of other additives may also permit
incorporation of higher levels of a particular copolymer
hereof, if desired.
Accordingly, while any effective amount, i.e.,
dispersant or viscosity index improving - dispersant
effective amount, of the additives of the present invention
can be incorporated into the fully formulated lubricating
oil composition, it is contemplated that such effective
amount be sufficient to provide said lube oil composition
with an amount of the àdditive of typically from about
0.001 to about 20, preferably about 0.01 to about 15, more
preferably from about 0.1 to about 10, and most preferably
from about 0.25 to about 5.0 wt. %, based on the weight of
said composition.
'- 78 - 20150~8
The following examples, which include preferred
embodiments and wherein all parts and percentages are by
weight unless otherwise indicated, further illustrate the
present invention.
Example 1 illustrates the preparation of an
ethylene-propylene copolymer of the instant invention.
EXAMPLE 1
An ethylene-propylene copolymer having an ethylene
content of about 56 wt. %, a thickening efficiency (T.E.)
of about 2.6, an Mw of about 105,000, an ~n
of about 96,000 a Mw/~n ~f 1.094 and
~z/~w of 1.086 is prepared in a tubular reactor
under the following condition:
Reactor Inlet Temp. (~F) -4
Reactor Outlet Temp. (~F) 57
Sidestream Feed Temp. (~F)-26
Catalyst Premix Temp. (~F)91
Catalyst Premix Time (Sec.) 7.87
Reactor Residence Time (Sec.)
at Sidestrem 1/21.26/1.40
Inlet Feed Rates (Klb /hr.)
Hexane 164.8
Ethylene 1.03
Propylene 15.36
VC14 0.03375
A12(C2Hs)3 C13 0.861
Sweep Hexane 4.926
Sidestrem Feed Rates (Klb./hr.)
Hexane 25
Ethylene 3.02
Propylene 5.84
Total Hexane (Klb./hr.)194.7
Sidestream Feed Splits (wt.%)
Sidestream 1/2 70/30
Example 2 illustrates the grafted, i.e., succinic
anhydride grafted, ethylene-propylene copolymer of the
instant invention.
20150~8
_ - 79 -
EXAMPLE 2
700 GRAMS OF A 15 WT. ~ SOLUTION IN s100 NLP
baseoil of a copolymer prepared in accordance with the
procedure of Example 1 are introduced into a one liter
reactor and heated to 175~C with nitrogen purge. 17.5
grams of maleic anhydride are charged to the reactor in 10
stages, each stage consisting of 1.75 grams of maleic
anhydride. After each charge of maleic anhydride, 0.28
gram of di-t-butyl peroxide is charged to the reactor as
initiator for the free radical grafting reaction. After
the last charge of di-t-butyl peroxide is introduced into
the reactor, the reaction mixture is stripped with nitrogen
for two hours. The total acidity of the reaction mixture
is 0.14 meq./g. of sample. The ~ and ~n of
the grafted copolymer are 101,000 ~w and 87,000
~n- The ~w/~n of this grafted
copolymer is 1.16, while the ~z/~w is 1.137.
Examples 3-4 illustrate the nitrogen containing
carboxylic acid material grafted ethylene-propylene
copolymer sof the instant invention.
EXAMPLE 3
Into a reactor vessel containing 150 grams of a
20% oil solution of the succinic anhydride grafted
ethylene-propylene copolymer of EXAMPLE 2 are charged 196
grams of S130N mineral oil and 4.4 grams of
N-isodecyloxypropyl-1,3-diaminopropane. The resulting
reaction mixture is heated to 190~C for two hours under
nitrogen sparging to form the nitrogen containing succinic
anhydride grafted ethylene-propylene copolymer.
EXAMPLE 4
Into a reactor vessel containing 150 grams of a
20% oil solution (20% active ingredient in 80% oil) of the
succinic anhydride grafted ethylene-propylene copolymer of
EXAMPLE 2 are charged 196 grams of S130N mineral oil and
7.3 grams of a tallow amine (a mixture of
- 80 - 201~0~8
N-dodecyl-tripropylene-tetraamine,N-tetradecyl-
tripropylene-tetraamine, N-hexadecyl-tripropylene-
tetraamine, N-heptadecyl-tripropylene-tetraamine,
N-octadecyl-tripropylene-tetraamine, andN-eicosyl-
tripropylene-tetraamine). The resulting reaction mixture
is heated to 190~C for two hours under nitrogen sparging to
form the nitrogen containing succinic anhydride grafted
ethylene-propylene copolymer.
