Note: Descriptions are shown in the official language in which they were submitted.
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POLYMERIC COMPOSITIONS COMPOSED OF ETHYLENE-VINYL ESTER
COPOLYMERS ALKYL (METH)ACRYLATES, PROCESSES FOR PRODUCTION
THEREOF AND USE THEREOF AS POUR POINT DEPRESSANTS FOR CRUDE OILS,
MINERAL OILS OR MINERAL OIL PRODUCTS
The present invention relates to polymeric compositions obtainable by free-
radical
polymerization of at least two different alkyl (meth)acrylates in the presence
of at least one
ethylene-vinyl ester copolymer, the alkyl (meth)acrylates used being a mixture
comprising
alkyl (meth)acrylates having linear C12- to C60-alkyl radicals and different
alkyl (meth)acry-
lates having linear C1- to Cii-alkyl radicals and/or branched Ca- to C60-alkyl
radicals and/or
cyclic C5- to C20- alkyl radicals. The invention further relates to the use of
such polymeric
compositions as pour point depressants for crude oils, mineral oils or mineral
oil products.
Underground mineral oil formations typically have relatively high
temperatures. After the
production of the crude oil to the surface, the crude oil produced therefore
cools down to a
greater or lesser degree according to the production temperature and the
storage or
transport conditions.
According to their origin, crude oils have different proportions of waxes,
which consist
essentially of long-chain n-paraffins. According to the type of crude oil, the
proportion of
such paraffins may typically be 1 to 30% by weight of the crude oil. When the
temperature
goes below a particular level in the course of cooling, the paraffins can
crystallize, typically
in the form of platelets. The precipitated paraffins considerably impair the
flowability of the
oil. The platelet-shaped n-paraffin crystals can form a kind of house-of-cards
structure
which encloses the crude oil, such that the crude oil ceases to flow, even
though the
predominant portion is still liquid. The lowest temperature at which a sample
of an oil still
just flows in the course of cooling is referred to as the pour point ("yield
point"). For the
measurement of the pour point, standardized test methods are used.
Precipitated paraffins
can block filters, pumps, pipelines and other installations or be deposited in
tanks, thus
entailing a high level of cleaning.
The deposit temperature of oil deposits is generally above room temperature,
for example
40 C to 100 C. Crude oil is produced from such deposits while still warm, and
it naturally
cools more or less quickly to room temperature in the course of or after
production, or else
to lower temperatures under corresponding climatic conditions. Crude oils may
have pour
points above room temperature, such that crude oils of this kind may solidify
in the course
of or after production.
It is known that the pour point of crude oils can be lowered by suitable
additives. This can
prevent paraffins from precipitating in the course of cooling of produced
crude oil. Suitable
additives firstly prevent the formation of said house-of-cards-like structures
and thus lower the
temperature at which the crude oil solidifies. In addition, additives can
promote the formation of
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fine, well-crystallized, non-agglomerating paraffin crystals, such that
undisrupted oil transport is
ensured. Such additives are also referred to as pour point depressants or flow
improvers.
Paraffin inhibitors or wax inhibitors refer to those substances intended to
prevent the deposition
of paraffins or paraffin waxes on surfaces in contact with crude oils or other
wax-containing oils
and/or mineral oil products.
The use of ethylene copolymers as flow improvers is known, especially that of
copolymers of
ethylene and unsaturated esters. Examples thereof are described in DE-A-21 02
469 or EP 84
148A2.
DE-A-16 45 785 discloses heating oil mixtures with a depressed pour point. The
mixtures
comprise at least 3% by weight of polymers having unbranched saturated side
chains having at
least 18 carbon atoms, for example homo- or copolymers of alkyl esters of
unsaturated mono-
and dicarboxylic acids and homo- or copolymers of various alkyl vinyl ethers.
DE-A-20 47 448 discloses additives for lowering viscosity in paraffin-based
crude oils. The
additives are mixtures of polyvinyl ethers and ethylene-vinyl acetate
copolymers.
EP 486 836 Al discloses mineral oil middle distillates, for example gas oils,
diesel oils or
heating oil, which comprise polymeric additives to improve the flow properties
under cold
conditions. The polymeric additives are a combination of customary ethylene-
based flow
improvers, for example copolymers of ethylene and vinyl acetate, vinyl
propionate or ethylhexyl
acrylate and copolymers of linear or branched C8- to C18-alkyl (meth)acrylates
and/or linear or
branched C18- to C28-alkyl vinyl ethers in a weight ratio of 40 : 60 to 95 :
5, and the copolymers
of the alkyl (meth)acrylates and/or alkyl vinyl ethers and the conventional
flow improvers may be
in the form of a mixture or the copolymers of the alkyl (meth)acrylates and/or
alkyl vinyl ethers
may wholly or partly be grafted onto the conventional flow improvers. The
alkyl radicals are
preferably unbranched, but up to 20% by weight of cyclic and/or branched
moieties may be
present. In the sole example for preparation of a graft copolymer, n-dodecyl
acrylate and n-
octadecyl vinyl ether are grafted onto a copolymer of ethylene and vinyl
propionate having a
mean molar mass Mn of approx. 2500 g/mol. The solvent used for the preparation
is
isoundecane, and aromatic solvents are used at a later stage for dilution.
US 4,608,411 discloses graft copolymers for prevention of wax deposition from
crude oils. The
main chain consists of a copolymer of ethylene and a monomer selected from the
group of vinyl
esters of C2- to C18-monocarboxylic acids, C1- to C12-esters of unsaturated
monocarboxylic
acids or unsaturated a,I3-dicarboxylic acids, or the esters or anhydrides
thereof. Onto this are
grafted homo- or copolymers of alkyl acrylates, the alkyl group thereof having
at least 12 carbon
atoms and at least 20% of the alkyl groups having at least 22 carbon atoms.
The solvents
proposed are various hydrocarbons.
,
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Such graft copolymers for use as pour point depressants are typically prepared
in chemical
production sites, and the products are transported from there to the site of
use, for example to
an oilfield or to an offshore platform. Such sites of use may be in cold
regions of the Earth. In
order to save transport costs, concentrates of the graft copolymers in
hydrocarbons are typically
produced, for example concentrates having a polymer content of 50 to 80% by
weight of
polymers. Such concentrates can be used as such or can be formulated by users
on site in the
desired manner to give ready-to-use formulations. For example, dilution with
solvent and/or
addition of further additives is possible.
Particularly advantageous pour point depressants can be obtained by preparing
said graft
copolymers based on ethylene-vinyl ester copolymers using alkyl
(meth)acrylates having C18 to
C22 carbon radicals. Such products, however, have the disadvantage that the
solutions thereof
in hydrocarbons, especially the concentrates mentioned, can solidify in the
course of cooling to
room temperature. They accordingly first have to be melted for use, which
means additional
work for the user.
It is therefore an object of the present invention to provide improved pour
point depressants for
crude oils, and these should be obtainable - analogously to the known products
- by free-radical
polymerization of alkyl (meth)acrylates in the presence of ethylene-vinyl
ester copolymers. The
improved products should have the same influence on the pour point as the
known products.
However, they should also be liquid in concentrated solution in hydrocarbons,
and it should thus
be possible to add them to crude oils in a simple manner.
Accordingly, polymeric compositions obtainable by free-radical polymerization
of
monoethylenically unsaturated monomers (A) in the presence of at least one
ethylene-vinyl
ester copolymer (B) have been found,
= the monomers (A) comprising at least 70% by weight of alkyl
(meth)acrylates (Al)
based on the amount of all monomers (A),
= the ethylene-vinyl ester copolymers (B) comprising 55 to 85% by weight of
ethylene
and 15 to 45% by weight of vinyl esters of the general formula H2C=CH-0-(0)C-
R1
(III) where R1 is H or a C1- to C4 hydrocarbyl radical, and
= the amount of the monomers (A) being 70 to 90% by weight and that of the
ethylene-vinyl ester copolymers (B) 10 to 30% by weight based on the sum of
the
monomers (A) and the ethylene-vinyl ester copolymers (B) together,
and the alkyl (meth)acrylates (Al) being a mixture of
(Ala) 50 to 99 mol% of at least one alkyl (meth)acrylate (Ala) of the general
formula
H2C=C(R2)-COOR3 where R2 is H or a methyl group and R3 is a linear alkyl
radical having 12 to 60 carbon atoms, and
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(Al b) 1 to 49 mol% of at least one alkyl (meth)acrylate (Al b) of the
general
formula H2C=C(R2)-COOR4 where R2 is as already defined and R4 is a
saturated aliphatic hydrocarbyl radical selected from the group of R4a, R4b
and R4c radicals and the radicals are each defined as follows:
R4a: linear alkyl radicals having 1 to 11 carbon atoms,
R4b: branched alkyl radicals having 4 to 60 carbon atoms, and
R4c: cyclic alkyl radicals having 5 to 20 carbon atoms,
with the proviso that the sum of the amounts of (Ala) and (Al b) adds up to
100 mol%.
More particularly, there is provided a polymeric composition obtained by free-
radical
polymerization of monoethylenically unsaturated monomers (A) in the presence
of at least
one ethylene-vinyl ester copolymer (B),
= the monomers (A) comprising at least 70% by weight of alkyl
(meth)acrylates
(Al) based on the amount of all monomers (A),
= the ethylene-vinyl ester copolymers (B) comprising 55 to 85% by weight of
ethylene and 15 to 45% by weight of vinyl esters of the general formula
H2C=CH-0-(0)C-R1 (Ill) where R1 is H or a to C4
hydrocarbyl radical, and
= the amount of the monomers (A) being 70 to 90% by weight and that of the
ethylene-vinyl ester copolymers (B) 10 to 30% by weight based on the sum of
the monomers (A) and the ethylene-vinyl ester copolymers (B) together,
wherein the alkyl (meth)acrylates (Al) are a mixture of
(Al a) 50 to 99 mol% of at least one alkyl (meth)acrylate (Al a) of the
general
formula H2C=C(R2)-COOR3 where R2 is H or a methyl group and R3 is a
linear alkyl radical having 18 to 24 carbon atoms, and
(Al b) 1 to 49 mol% of at least one alkyl (meth)acrylate (Al b) of the
general
formula H2C=C(R2)-COOR4 where R2 is as already defined and R4 is a
hydrocarbyl radical selected from the group of R4a, R4b and Ric radicals and
the radicals are each defined as follows:
R4a: linear alkyl radicals having 1 to 11 carbon atoms,
R4b: branched alkyl radicals having 4 to 60 carbon atoms, and
R4c: cyclic alkyl radicals having 5 to 20 carbon atoms,
with the proviso that the sum of the amounts of (Ala) and (Al b) adds up to
100 mol%.
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4a
In a preferred embodiment of the invention, the polymeric composition further
comprises
hydrocarbons as solvents, more preferably hydrocarbons having a flashpoint 60
C.
In a further aspect of the invention, the use of the said polymeric
composition, preferably
dissolved in hydrocarbons, as a pour point depressant for crude oil, mineral
oil and/or
mineral oil products has been found, by adding at least one polymeric
composition of said
type to the crude oil, mineral oil and/or mineral oil products.
More particularly, the invention relates to the use of the polymeric
composition as defined
in the invention as a pour point depressant for an oil selected from the group
consisting of
crude oil, mineral oil, mineral oil products and mixtures thereof.
The invention also relates to the use of the polymeric composition as defined
in the
invention for prevention of wax deposits on surfaces in contact with crude
oil, mineral oil
and/or mineral oil products.
Specific details of the invention are as follows:
Starting materials used
Monomers (A)
The monomers (A) used are monoethylenically unsaturated monomers, with the
proviso
that at least 70% by weight of the monomers (A) are alkyl (meth)acrylates
(Al). According
to the invention, the alkyl (meth)acrylates (Al) are a mixture of at least one
alkyl
(meth)acrylate (Ala) and at least one alkyl (meth)acrylate (Al b).
Alkyl (meth)acrylates (Al)
Alkyl (meth)acrylates (Ala
The alkyl (meth)acrylates (Ala) have the general formula H2C=C(R2)-COOR3 where
R2 is
H or a methyl group and R3 is a linear alkyl radical having 12 to 60 carbon
atoms,
preferably 16 to 30 carbon atoms, more preferably 18 to 24 carbon atoms and,
for
example, 18 to 22 carbon atoms. R3 may be a 1-hexadecyl radical, 1-octadecyl
radical, 1-
nonadecyl radical, 1-eicosyl radical, 1-heneicosyl radical, 1-docosyl radical,
1-tetracosyl
radical, 1-hexacosyl radical, 1-octacosyl radical or 1-triacontyl radical. It
will be appreciated
_________________________________________________________________ that it is
also possible to use a mixture of
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various alkyl (meth)acrylates (Ala). For example, it is possible to use
mixtures in which R3
represents C16 and C18 radicals or C18, C20 and C22 radicals.
In a preferred embodiment, at least one of the alkyl (meth)acrylates (Ala)
used is 1-docosyl
5 (meth)acrylate (behenyl acrylate), i.e. R3 is a linear alkyl radical
having 22 carbon atoms. In a
particularly preferred embodiment of the invention, at least 40% by weight of
the alkyl
(meth)acrylates (Ala) used is 1-docosyl (meth)acrylate. Advantageously, it is
possible to use
mixtures comprising 1-octadecyl (meth)acrylate, 1-eicosyl (meth)methacrylate
and 1-docosyl
(meth)acrylate. Such mixtures of various (meth)acrylates are also commercially
available. As
well as the C18/C20/C22 (meth)acrylates mentioned, they may also comprise
small amounts of
(meth)acrylates with a higher or lower carbon number as by-products. For
example, mixtures
may comprise 40 to 55% by weight of 1-octadecyl (meth)acrylate, 10 to 15% by
weight of 1-
eicosyl (meth)methacrylate and 35 to 45% by weight of 1-docosyl
(meth)acrylate.
Alkyl (meth)acrylates (Al b)
The alkyl (meth)acrylates (Alb) have the general formula H2C=C(R2)-COOR4 where
R2 is as
already defined and R4 is a saturated aliphatic hydrocarbyl radical selected
from the group of
R4a, R4b and R4c radicals and the radicals are each defined as follows:
R4a: linear alkyl radicals having 1 to 11, preferably 2 to 10 and more
preferably 2 to 6 carbon
atoms,
Rim: branched alkyl radicals having 4 to 60, preferably 4 to 30, more
preferably 4 to 17, carbon
atoms, and
R4o: cyclic alkyl radicals having 5 to 20, preferably 6 to 12, more preferably
6 to 10 and, for
example, 10 carbon atoms.
Examples of linear alkyl radicals R4a comprise ethyl, n-propyl, n-butyl, n-
pentyl, n-hexyl, n-
heptyl, n-octyl, n-nonyl, n-decyl and n-undecyl radicals, preference being
given to n-propyl, n-
butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl radicals,
particular preference to
ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl radicals and very particular
preference to n-butyl
radicals.
Branched alkyl radicals R4b may be singly or multiply branched. Examples of
branched radicals
Rai) comprise i-butyl, t-butyl, 2,2'-dimethylpropyl, 2-ethylhexyl, 2-
propylheptyl, i-nonanol, i-decyl,
i-tridecyl, i-heptadecyl radicals, preference being given to t-butyl, 2-
ethylhexyl and 2-
propylheptyl radicals.
Cyclic alkyl radicals may R4c may be monocyclic or polycyclic, especially
bicyclic. They may
additionally be substituted by linear and/or branched alkyl radicals. Examples
of cyclic alkyl rad-
icals Rem comprise cyclopentyl, cyclohexyl, 4-methylcyclohexyl, cycloheptyl,
bicyclo[2.2.1]heptyl,
bicyclo[2.2.2]octyl or 2-(1,7,7-trimethylbicyclo[2.2.1]heptyl radicals.
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In one embodiment of the invention, the R4 radicals are R4a and R46 radicals.
In a preferred embodiment, the R4 radicals are R4b radicals, preferably R4b
radicals having 4 to
30 carbon atoms, more preferably R4b radicals having 4 to 17 carbon atoms.
In a further preferred embodiment, the R4 radicals are R4c radicals,
preferably R4c radicals
having 6 to 10 carbon atoms.
It will be appreciated that it is also possible to use a mixture of various
alkyl (meth)acrylates
(Al b).
Further monomers (A)
As well as the monomers (Al), it is optionally also possible to use further
monoethylenically
unsaturated monomers (A2) other than the monomers (Al), i.e. the monomers
(Ala) and (Alb).
With the aid of further monomers (A) as well as the alkyl (meth)acrylates
(Al), it is possible to
modify the properties of the inventive polymeric compositions and match them
to the desired
properties. The person skilled in the art makes a suitable selection.
Further monomers (A2) may especially be (meth)acrylates which comprise
hydrocarbyl radicals
and do not correspond to the above definition of the monomers (Ala) and (Alb).
These include especially (meth)acrylates (A2a) of the general formula H2C=CHR2-
COOR6
where R2 is as defined above and R6 is an unsubstituted or alkyl-substituted
aromatic
hydrocarbyl radical having 6 to 30, preferably 6 to 18, carbon atoms. Examples
of aromatic
hydrocarbyl radicals R6 comprise phenyl, 4-methylphenyl, benzyl or 2-
phenylethyl radicals.
Further monomers (A2) may also be (meth)acrylates of the general formula
H2C=C(R2)-COOR6
(A2b) where R2 is H or methyl and R6 is a linear or branched, aliphatic and/or
aromatic
hydrocarbyl radical 1 to 60, preferably 2 to 30, carbon atoms, which radical
may be substituted
by OH groups and/or in which nonadjacent carbon atoms may be replaced by
oxygen atoms. In
other words, R3 radicals may thus comprise OH groups and/or ether groups ¨0¨.
Examples of
(meth)acrylates (A2b) comprise hydroxyethyl (meth)acrylate, hydroxypropyl
(meth)acrylate,
phenoxyethyl acrylate, or polypropylene glycol mono(meth)acrylate.
Further monomers (A2) may also be (meth)acrylates of the general formula
H2C=C(R2)-COOR7
(A2c) where R2 is H or methyl and R7 is unsubstituted or alkyl-substituted
saturated cyclic
aliphatic hydrocarbyl radicals having 5 to 30, preferably 6 to 17, carbon
atoms. An example of
an R7 radical is a cyclohexyl radical.
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Further monomers (A2) may also be vinyl esters of the general formula H2C=CH-0-
(0)C-R7
(A2d) where R7 is a linear or branched alkyl radical having 1 to 60 carbon
atoms, preferably 2 to
30 carbon atoms. Examples of R7 radicals comprise methyl, ethyl, n-propyl or n-
butyl radicals.
Amounts of the monomers (A)
According to the invention, 50 to 99 mol% of the monomers (Al) are monomers
(Al a) and 1 to
50 mol% of the monomers (Al) are monomers (Alb), with the proviso that the sum
of (Ala) and
(Alb) adds up to 100 mol%. In other words, the monomers (Al) are thus
exclusively a mixture
of monomers (Ala) and (Al b). Preference is given to using 50 to 90 mol% of
monomers (Ala)
and 10 to 50 mol% of monomers (Al b), particular preference to using 70 to 90
mol% of
monomers (Ala) and 10 to 30 mol% of monomers (Al b).
When cyclic alkyl radicals RIG are used, it has been found to be particularly
useful to use 50 to
80 mol% of monomers (Ala) and 20 to 50 mol% of monomers (Al b), preferably 55
to 75 mol%
of monomers (Ala) and 25 to 45 mol% of monomers (Al b).
According to the invention, the amount of the alkyl (meth)acrylates (Al) is at
least 70% by
weight, preferably at least 80% by weight, more preferably at least 95% by
weight, based on the
total amount of all monomers (A). The monomers (A) are most preferably
exclusively alkyl
(meth)acrylates (Al).
Ethylene-vinyl ester copolymers (B)
The ethylene-vinyl ester copolymers (B) used comprise ethylene and vinyl
esters of the general
formula H2C=CH-0-(0)C-R1. In this formula, R1 is H or a Cl- to C4-hydrocarbyl
radical, for
example a methyl, ethyl, n-propyl or n-butyl radical. R1 is preferably H,
methyl or ethyl and more
preferably methyl.
As well as ethylene and the vinyl esters, further monomers may optionally also
be present. The
amount of such further monomers should, however, not exceed 20% by weight,
preferably 10%
by weight, based on the amount of all monomers, and particular preference is
given to the
presence of no further monomers aside from ethylene and the vinyl esters.
The amount of ethylene in the ethylene-vinyl ester copolymers (B) is 55 to 85%
by weight and
the amount of vinyl esters is 15 to 45% by weight based on the amount of all
monomers.
Preferably, the amount of ethylene is 55 to 75% by weight and the amount of
vinyl esters 25 to
45% by weight, more preferably 30 to 40% by weight, and, most preferably, the
amount of
ethylene is 60 to 70% by weight and the amount of vinyl esters 30 to 40% by
weight.
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The weight-average molecular weight M,, of the ethylene-vinyl ester copolymers
(B) used is
preferably at least 30 000 g/mol, for example 30 000 g/mol to 200 000 g/mol,
preferably 50 000
g/mol to 150 000 g/mol.
Polymeric composition and production thereof
The inventive polymeric compositions are obtainable by free-radical
polymerization of the
monomers (A) in the presence of the ethylene-vinyl ester copolymers (B).
The mixing ratio of monomers (A) and ethylene-vinyl ester copolymers (B) is
selected according
to the desired properties of the polymeric composition to be synthesized, and
the amount of the
monomers (A) should be at least 50% by weight based on the sum of monomers (A)
and
ethylene-vinyl ester copolymers (B). In general, the amount of the monomers
(A) is 70 to 90%
by weight and that of the ethylene-vinyl ester copolymers (B) 10 to 30% by
weight. Preferably,
the amount of the monomers (A) is 75 to 85% by weight and that of the ethylene-
vinyl ester
copolymers (B) 15 to 25% by weight.
Solvents
In a preferred embodiment of the invention, the polymeric composition further
comprises
suitable solvents. The polymeric composition should be homogeneously
dispersed, preferably
dissolved, therein. In principle, all solvents which meet these requirements
are suitable. It is of
course also possible to use mixtures of different solvents.
The concentration of the polymeric composition in the solvents is selected by
the person skilled
in the art according to the desired properties of the formulation to be
produced. In a preferred
embodiment of the invention, the concentration is 20 to 80% by weight,
preferably 30% by
weight to 70% by weight and, for example, 40 to 55% by weight of the polymeric
composition
based on the sum of all components of the composition including solvents used.
The use of a
concentrate has the advantage that the transport costs from the site of
production to the site of
use, for example an oil production installation, can be kept low.
The solvents may, for example, be nonpolar solvents comprising saturated
aliphatic hydrocarbyl
groups, preferably those having a flashpoint 60 C. Examples of such solvents
comprise
saturated aliphatic hydrocarbons, saturated aliphatic alcohols or esters of
saturated aliphatic
carboxylic acids and saturated aliphatic alcohols, with the proviso that the
solvents each have a
flashpoint 60 C. Examples of alcohols comprise aliphatic alcohols having at
least 8 carbon
atoms, such as 1-octanol, 1-decanol or 1-dodecanol. Examples of esters
comprise esters of
saturated fatty acids having at least 8 carbon atoms with saturated aliphatic
alcohols, for
example methyl laurate or methyl stearate. Technical mixtures of various
aliphatic esters are
commercially available. In a further embodiment of the invention, it is
possible to use esters of
aliphatic or cycloaliphatic dicarboxylic acids, for example dialkyl esters of
cyclohexane-1,2-
dicarboxylic acid, such as diisononyl cyclohexane-1,2-dicarboxylate.
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In a preferred embodiment of the invention, solvents used are hydrocarbons.
These may be
aliphatic, cycloaliphatic and/or aromatic hydrocarbons. Preference is given to
hydrocarbons or
hydrocarbon mixtures having a flashpoint 60 C.
The hydrocarbons may, for example, be saturated aliphatic solvents or solvent
mixtures. These
may be either paraffinic or naphthenic, i.e. saturated cyclic, hydrocarbons.
Preference is given
to high-boiling aliphatic hydrocarbons having a boiling point of at least 175
C and preferably a
flashpoint 2 60 C. Suitable hydrocarbons having a flashpoint 2 60 C comprise,
for example, n-
undecane (flashpoint 60 C, boiling point 196 C) or n-dodecane (flashpoint 71
C, boiling point
216 C). It is possible with preference to use technical mixtures of
hydrocarbons, for example
mixtures of paraffinic hydrocarbons, mixtures of paraffinic and naphthenic
hydrocarbons or
mixtures of isoparaffins. It will be apparent to those skilled in the art that
technical mixtures may
still comprise small residues of aromatic or unsaturated hydrocarbons. The
content of aromatic
and/or unsaturated hydrocarbons should, however, be generally <1% by weight,
preferably <
0.5% by weight and more preferably < 0.1% by weight. Technical mixtures of
saturated aliphatic
solvents are commercially available, for example technical mixtures of the
Shellsol D series or
the Exxsol D series.
The hydrocarbons may also be aromatic solvents or solvent mixtures. In one
embodiment of the
invention, the hydrocarbons are toluene or a solvent mixture comprising
toluene. In a further
embodiment, the hydrocarbons are high-boiling aromatic hydrocarbons having a
boiling point of
at least 175 C and preferably a flashpoint 60 C. Suitable aromatic
hydrocarbons having a
flashpoint .2 60 C comprise, for example, naphthalene. It is possible with
preference to use
technical mixtures of aromatic hydrocarbons. Technical mixtures of aromatic
solvents are
commercially available, for example technical mixtures of the Shellsol A
series or the
Solvesso series.
It is particularly advantageously possible to use mixtures of aliphatic
hydrocarbons having a
flashpoint 60 C and aromatic hydrocarbons having a flashpoint 60 C.
Free-radical polymerization
The performance of such free-radical polymerizations is known in principle to
those skilled in the
art. The free-radical polymerization can in principle be performed by means of
a bulk
polymerization, by polymerizing the monomers (A) in the presence of the
ethylene-vinyl ester
copolymers (B) and of an initiator for free-radical polymerization and in the
absence of solvents.
Details of this are described in EP 486 836 Al, page 4 lines 38 to 46.
In a preferred embodiment of the invention, the preparation is undertaken by
means of a
solution polymerization. Suitable solvents for this purpose are in principle
all of those in which
the monomers (A), the ethylene-vinyl acetate copolymers (B) and the polymeric
composition
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formed ¨ even in the high concentration desired ¨ have sufficient solubility
or are at least
homogeneously dispersed and which do not enter into any unwanted reactions in
the course of
the polymerization. More particularly, they should not themselves be
polymerizable and not
have any excessive regulating action.
5
The solvents are preferably hydrocarbons, preferably the above-described
aliphatic and/or
aromatic hydrocarbons, especially those having a flashpoint 60 C.
Advantageously, in the
case of such a procedure, a ready-to-use solvent-comprising polymeric
composition which can
be used as a pour point depressant is obtained, without any requirement for
further workup
10 steps after the polymerization.
For the polymerization in solution, a solution of the alkyl (meth)acrylates
(Ala), the alkyl
(meth)acrylates (Al b), optionally further monomers (A) and the copolymers (B)
is first provided
in the selected solvent, preferably in hydrocarbons. The solvent may, for
example, be toluene.
The dissolution is effected by vigorous mixing of the components, for example
by stirring. For
example, it is possible first to dissolve the monomers (A) and then to add
solid ethylene-vinyl
ester copolymer (B) to the solution, or first to dissolve ethylene-vinyl ester
copolymers (B) and to
add the monomers (A). The dissolution can be accelerated by increasing the
temperature, for
example to about 50 to 80 C.
In one variant of the invention, a solution of the alkyl (meth)acrylates (Ala)
in hydrocarbons,
preferably aliphatic hydrocarbons having a flashpoint 60 C can be provided, by
esterifying
(meth)acrylic acid with alcohols R3OH in hydrocarbons and using the resulting
solution, after
mixing with the further components, for polymerization. The esterification can
be performed by
methods known in principle to those skilled in the art, for example by the
processes described
by EP 486 836 Al.
The free-radical polymerization is effected using thermal initiators for free-
radical
polymerization. Naturally, the initiators used are selected such that they are
soluble in the
polymerization medium. Preferred polymerization initiators comprise oil-
soluble azo compounds,
especially those having a 10 h half-life of 50 C to 70 C. Examples of suitable
initiators comprise
dimethyl 2,2`-azobis(2-methylpropionate) (10 h half-life approx. 66 C), 2,2'-
azobis(2-
methylbutyronitrile) (10 h half-life approx. 67 C or 2,2`-azobis(2,4-
dimethylvaleronitrile) (10 h
half-life approx. 51 C). Such initiators are commercially available (from
Wako). The weight ratio
of monomers A to the initiators is generally about 100:1 to 150:1, preferably
125:1 to 140:1. It is
possible for the entire amount of the initiators to be present at the start of
the polymerization,
but preference is given to adding the initiator gradually. The addition may be
in portions or
continuous, preferably continuous.
In addition, molecular weight regulators can be added in a manner known in
principle. Examples
of regulators comprise alcohols such as isopropanol, allyl alcohol or buten-2-
ol, thiols such as
ethanethiol, or aldehydes such as crotonaldehyde. The amount of the molecular
weight
PF73680 CA 02889070 2015-04-20
11
regulators is generally 1 to 4% by weight based on the monomers (A),
preferably 2 to 3% by
weight based on the monomers (A).
The free-radical polymerization is triggered in a manner known in principle by
heating the
reaction mixture. The polymerization temperature should be above the 10 h half-
life of the
initiator and is generally at least 50 C. A useful polymerization temperature
has been found to
be from 50 to 90 C. In general, the polymerization is undertaken in a manner
known in principle
under a protective gas such as nitrogen or argon.
The polymerization in solution can be undertaken by initially charging the
solution of the starting
materials in a suitable, typically stirred, reaction vessel, appropriately
with preceding
performance of the dissolution in the apparatus. The concentration of the
monomers (A) in the
solvents is selected by the person skilled in the art according to the desired
properties of the
mixture to be produced. In a preferred embodiment of the invention, the
concentration is 40 to
80% by weight, for example 45% by weight to 55% by weight. If desired, one or
more molecular
weight regulators are added to the solution. After the desired polymerization
temperature has
been attained, a solution of the polymerization initiator is added gradually
to the mixture to be
polymerized. The duration of addition may be 0.5 h to 10 h, without any
intention to restrict the
invention to this range. The completion of addition of the initiator should
generally be followed
by a further polymerization time. This may, for example, be 0.5 to 5 h. A
solution of the inventive
polymer mixture is obtained.
By means of the production process described, it is possible to obtain a
polymeric composition,
preferably a polymeric composition in solvents, preferably hydrocarbons. The
polymerization of
the monomers (A) in the presence of the ethylene-vinyl ester copolymers (B)
prevents the
polymer components from separating from one another in solution. The result of
the
polymerization reaction is different when the monomers (A) - under otherwise
identical
conditions - are polymerized separately from the ethylene-vinyl ester
copolymers (B) and
solutions of a polymer formed from the monomers (A) and a solution of the
ethylene-vinyl ester
copolymers (B) are combined after the polymerization. Such mixtures can
separate again.
Although we do not wish to be bound to a particular theory, this effect can be
explained by at
least partial grafting of the monomers (A) onto the ethylene-vinyl ester
copolymer (B) in the
course of polymerization. A further portion of the monomers may polymerize
without being
grafted on. This gives rise to ethylene-vinyl ester graft copolymers with side
groups comprising
monomers (A), and homo- or copolymers comprising monomers (A). In a manner
known in
principle, the partial grafting prevents separation of the two polymer
components. It is also
possible that no significant grafting occurs, but that an "interjacent
complex" forms from the
ethylene-vinyl ester copolymers (B) and the homo- or copolymers of monomers
(A). In such a
complex, the polymers are predominantly physically bound and nevertheless
stable, as
described, for example, in US 7,001,903 B2.
P F73680 CA 02889070 2015-04-20
12
Use of the formulations as pour point depressants
The resulting polymeric compositions, especially polymeric compositions in
hydrocarbons,
preferably those having a flashpoint 60 C, can be used in accordance with the
invention as
pour point depressants for crude oil, mineral oil and/or mineral oil products,
by adding at least
one of the polymer formulations detailed to the crude oil, mineral oil and/or
mineral oil products.
In addition, it is of course also possible to use further formulations which
act as pour point
depressants.
Pour point depressants reduce the pour point of crude oils, mineral oils
and/or mineral oil
products. The pour point ("yield point") refers to the lowest temperature at
which a sample of an
oil, in the course of cooling, still just flows. For the measurement of the
pour point, standardized
test methods are used.
For the inventive use, the polymeric composition can be used as such.
Preference is given, however, to using formulations of the polymeric
compositions in suitable
solvents which may comprise further components as well as the solvents.
It is possible to use a concentrate, for example a concentrate having a total
polymer content of
50% by weight to 80% by weight in solvents. Such a concentrate can be produced
by means of
the abovementioned process. However, it is also possible to dilute with
further solvent,
preferably to formulate with aliphatic and/or aromatic hydrocarbons and/or
with further
components.
For example, additional wax dispersants can be added to the formulation. Wax
dispersants
stabilize paraffin crystals which have formed and prevent them from
sedimenting. The wax
dispersants used may, for example, be alkylphenols, alkylphenol-formaldehyde
resins or
dodecylbenzenesulfonic acid. The concentration of a usable formulation may,
for example, be
20 to 50% by weight, preferably 25 to 40% by weight, of polymers prepared in
accordance with
the invention and optionally further components except for the solvents, this
figure being based
on the total amount of all components including the solvents. While the
formulations are
naturally produced in a chemical plant, the ready-to-use formulation can
advantageously be
produced on site, i.e., for example, directly at a production site for oil.
The inventive use is effected by adding the inventive polymeric compositions
or the formulations
comprising polymeric compositions to the crude oil, mineral oil and/or mineral
oil products,
preferably to the crude oil.
It is the advantage of the inventive polymeric compositions which are produced
using a
combination of at least one alkyl (meth)acrylate (Ala) and at least one alkyl
(meth)acrylate
(Al b) that the solutions thereof in hydrocarbons are still liquid, even at
room temperature, at a
concentration of about 45% by weight to 70% by weight. Such concentrates can
be used
PF73680 CA 02889070 2015-04-20
13
without any requirement for melting of the concentrates prior to use. This
makes it quite
considerably easier to work with the products.
The formulations are typically used in such an amount that the amount of the
polymeric
composition added is 50 to 1500 ppm based on the oil. The amount is preferably
100 to 1000
ppm, more preferably 250 to 600 ppm and, for example, 300 to 600 ppm. The
amounts are
based on the polymeric composition itself, not including any solvents present
and optional
further components of the formulation.
In a preferred embodiment of the invention, the oil is crude oil and the
formulation is injected
into a crude oil pipeline. The injection can preferably be effected at the
oilfield, i.e. at the start of
the crude oil pipeline, but the injection can of course also be effected at
another site. More
particularly, the pipeline may be one leading onshore from an offshore
platform. Explosion
protection is particularly important on offshore platforms and in refineries,
and the inventive
formulations based on solvents having a flashpoint 60 C accordingly simplify
working quite
considerably. Moreover, the cooling of crude oil in underwater pipelines
leading onshore from
an offshore platform is naturally particularly rapid, especially when the
pipelines are in cold
water, for example having a water temperature of less than 10 C.
In a further embodiment of the invention, the oil is crude oil and the
formulation is injected into a
production well. Here too, the production well may especially be a production
well leading to an
offshore platform. The injection is preferably effected approximately at the
site where oil from
the formation flows into the production well. In this way, the solidification
of the crude oil in the
production well or an excessive increase in its viscosity can be prevented.
Further uses of the formulations
The inventive polymeric composition can of course also be used for other
purposes.
In a further embodiment of the invention, the above-detailed polymeric
compositions, especially
formulations in solvents, especially hydrocarbons, are used to prevent wax
deposits on surfaces
in contact with crude oil, mineral oil and/or mineral oil products. The use is
effected by adding at
least one of the above-detailed polymer formulations to the crude oil, mineral
oil and/or mineral
oil products. Preferred formulations have already been mentioned, and the
manner of use is
also analogous to the use as a pour point depressant. As well as the inventive
formulations, it is
of course also possible to use further formulations which act as wax
inhibitors.
CA 02889070 2015-04-20
BASF SE INV 0073680 PF73680 EP/US
14
The following examples are intended to illustrate the invention in detail:
A Production of the polymer mixtures
Starting materials used:
ethylene-vinyl acetate ethylene-vinyl acetate copolymer formed from 67% by
weight of
copolymer ethylene and 33% by weight of vinyl acetate, melt
flow index 21 g/10
min (measured to ASTM D 1238), Mn approx. 34 000 g/mol, Mõõ,
approx. 134 000 g/mol.
Wako V-601 dimethyl 2,2`-azoisobutyrate, 10 h half-life approx.
66 C (in toluene)
behenyl acrylate technical mixture of C18, Czo and C22 acrylates with
a linear alkyl
radical, 40 to 55% by weight of C18 acrylate, max. 15% by weight of
C20 acrylate and 35 to 45% by weight of C22 acrylate
butyl acrylate
t-butyl acrylate
2-propylheptyl acrylate
2-propylheptyl methacrylate
cyclohexyl methacrylate
i-tridecyl acrylate acrylate with a branched tridecyl radical; the
radical has an average
of about 3 branches.
i-heptadecyl acrylate acrylate with a branched heptadecyl radical; the
radical has an
average of about 3 branches.
i-nonyl acrylate acrylate with a nonyl radical; the remainder is a
mixture of various
isomers
2-hydroxyethyl acrylate
hydroxypropyl acrylate
polypropylene glycol acrylate with polypropylene radical having an average
of 6 propylene
monoacrylate oxide units
C16/18'04E0)11 methacrylate formed from a C16/18 fatty alcohol
(mixture of n-
methacrylate hexadecanol (approx. 30%) and n-octadecanol (approx.
70%)
alkoxylated with an average of 11 ethylene oxide units.
phenoxyethyl acrylate H2C = CH-COO-CH2-CH2O-C8H5
isobornyl acrylate 2-(1,7,7-trimethylbicyclo [2.2.1]heptyl)acrylate
15
H3 j5C CH33
0)r./H2
0
Experimental method for example 3 in table 1:
Copolymer of 80:20 (wt/wt) behenyl acrylate I 2-propylheptyl acrylate
In a four-neck flask with TeflonTm stirrer, jacketed coil condenser and
Dosimat, 216.8 g of behenyl
acrylate and 54.2 g of propylheptyl acrylate are dissolved in 217 g of toluene
at 75 C, then 66.4 g of
the abovementioned ethylene-vinyl acetate copolymer are added while stirring
and dissolved. At 78
¨ 80 C, 8.2 g of ally' alcohol in 3.2 g of toluene, then 1.15 g of the
dimethyl 2,2'-azoisobutyrate
initiator (Wako V-601) dissolved in 31.4 g of toluene are metered in over the
course of 4 hours.
After further polymerization at 82 C for 2.5 hours, the mixture is diluted
with 106.3 g of toluene and
cooled to 40 C, before 0.42 g of triethanolamine is added. After stirring for
a further 30 min, the
mixture is filtered through a 280 pm fast sieve.
The resulting solution had a concentration of 48% by weight of the polymeric
composition.
Further examples and the comparative examples were performed by the same
method, except that
the type of 2nd acrylate and the ratio of behenyl acrylate to the 2nd acrylate
was altered. The
selected monomers and ratios are each compiled in table 1. The resulting
concentration of the
polymeric composition in all experiments was 48% by weight.
B Test of the properties of the polymeric compositions obtained
The solutions of the copolymers obtained were used to conduct each of the
following tests:
Determination of the K values of the copolymers
The K values of the copolymers obtained (measured according to H. Fikentscher,
Cellulosechemie,
volume 13, pages 58 to 64 and 71 to 74 (1932)) were determined in 2%
(wt./vol.) toluenic solution.
The values are compiled in table 1.
Molecular weight determination
The number-average molecular weight Mn and the weight-average molecular weight
M,, of each of
the copolymers obtained were determined by means of gel permeation
chromatography in
tetrahydrofuran as the solvent. The values are compiled in table 1.
CA 2839070 2017-07-28
P F73680 CA 02889070 2015-04-20
16
Determination of viscosity:
The kinematic viscosity of each of the solutions of the graft copolymers
obtained in the
experiments described above was measured with an Ubbelohde viscometer at 50 C.
The
values are compiled in table 1.
Assessment of stability
The stability of each polymer solution was determined, specifically with
respect to whether a
solution which has prolonged stability and does not have a tendency to phase
separation is
maintained. For this purpose, the formulations produced, after synthesis, were
stored at room
temperature. If noticeable phase separation occurs within 24 h after
commencement of storage,
the assessment is negative (-), otherwise (+). The values are compiled in
table 1.
Determination of the pour point
The determination of the pour point was conducted to ASTM D 5853 "Test Method
for Pour
Point of Crude Oils". The pour point is the minimum temperature at which a
sample of a tested
oil is still just free-flowing. According to ASTM D 5853, for this purpose, a
sample of the oil is
cooled in steps of 3 C each and the flowability is tested after each step. For
the tests, a crude
oil from the "Landau" oilfield in south-west Germany (Wintershall Holding
GmbH) having an API
gravity of 37 and a pour point of 27 C was used. To determine the lowering of
the pour point,
the graft copolymers to be tested were used to the oil in a concentration of
100 ppm, 300 ppm
or 1500 ppm, in each case of polymer based on the crude oil. The values are
compiled in table
1. Double or triple determinations were conducted on some samples. In these
cases, all
measurements are reported in the table.
-13
-11
-4
ca
No. 2nd acrylate behenyl acrylate / Viscosity at Stability
Mn K value Pour point [ C] co
cm
2nd acrylate 50 C at RT M.
Amount of the additives ci
Mass Molar [mm2/s] [g/mol] 100 300 1500
ratio ratio ppm PPm PPm
+ - 2230
Cl - 100 / 0 100
/ 0 6/6/9 3/0/3 9/6/6
179 solid 57000
n-butyl acrylate + 7330
90 / 10 77 / 23 269 41.3 6/9/12 6/6/6 9/0/9
liquid 10600
n-butyl acrylate + 8290
6 80 / 20 60 / 40 315 43.3
12/12 9/6/3 9/6/9
liquid 132000
tert-butyl acrylate + 7110
7 90 / 10 77 / 23 258 40.2
12/12/12 6/3/9/6 12/12/9
liquid 102000
tert-butyl acrylate 6930
8 85 / 15 67 133 296 liquid
42.8 6/9 6/6 9/6 R
107800
2
.
.
tert-butyl acrylate + 8280
'
w
9 80 / 20 60 / 40 324 43.2
6/6/-3 3/0/9 0/6/0 .
liquid 130000
..,
i,
tert-butyl acrylate + 7920
.. .
75 / 25 52 /48 341 44.8 6/9 9/9
3/3 V 15
liquid 123700
o
.i.
.
_______________________________________________________________________________
_____________________________ i
tert-butyl acrylate + 14640
NO
i.
03 50 / 50 27 /73 218 47.2
27/24 27/27 24/24
liquid 219800
. _____
2-propylheptyl acrylate + + 4170
1 90 / 10 85 / 15
36.7 6/6/9 6/0/6 0/9/6
163 liquid 65300
2-propylheptyl acrylate 85 / 15 + + 6100
2 77 / 23 42.4 9/9
6/6 6/6
296 liquid 110800
2-propylheptyl acrylate + + 9700
3 80 / 20 71 / 29
39.2 6/6 6/3/3 6/3/-3
227 liquid 95800
Table 1: Results of the examples and comparative examples
13
m
v
co
co
a)
No. 2nd acrylate behenyl acrylate / Viscosity Stability
Mn K value Pour point [ C] a
2nd acrylate at 50 C at RT Mõ
Amount of the additives
Mass Molar ratio [mm2/s] [g/mol] 100 300 1500
ratio µ PPm
PPm PPm
+ + 7500
4 2-propylheptyl acrylate 75 / 25 64 / 36
39.4 3/6 3/3 6/6
223 liquid 79800
2-propylheptyl acrylate + + 10900
C2 50 / 50 38 / 62 ,
38.8 12/9/9 12/9/9 6/6
211 liquid 90900
2-propylheptyl methacrylate 5590
11 90 / 10 85 / 14 227 40
9/9 9/9 12/6
gelated 87700
,
_______________________________________________________________________________
___________
2-propylheptyl methacrylate + 6030
12 80 / 20 72 / 28 283 40.8
9/6 6/6 6/6
liquid 104000 R
_
_______________________________________________________________________________
_______________________________ 2
+ 6290
.
13 i-nonanol acrylate 90/10 84/16 232 39.2
6/9 0/3 9/9 '
w
liquid 88030 .
..,
,
_ .
.
+
6740 ¨1
14 i-nonanol acrylate 80/20 71/29 237 39.6
6/9 3/3 9/9 co '
liquid 92000 L7,
i.
ii.
i-tridecyl acrylate + 5640
1
15 90 / 10 87 I 13 222 38.2
9/9 6/6 9/9
i.
liquid 81600
i-tridecyl acrylate + 6940
16 80/ 20 75/ 25 220 39.0
9/9 9/9 15/18
liquid 83000
_
+ 4980
17 i-heptadecyl acrylate 90 / 10 89 / 11 197 39.7
6/9 3/6 6/6
liquid 78300
+ 5450
18 i-heptadecyl acrylate 80 / 20 78/ 22 302 40.3
9/9 6/6 6/6
liquid 89390
+ 9490
19 cyclohexyl methacrylate 75 / 25 59 / 41 743 47.3
3/3 -3/-3 0/0
liquid 199000
+ 7350
20 isobornyl acrylate 80 I 20 70/ 30 244 38
9/9 6/6 9/12
liquid 80100
Table 1 (cont.): Results of the examples and comparative examples
,
..
-0
11
--4
CA)
Co
cn
o
No. 2nd acrylate behenyl acrylate / Viscosity at
Stability Mn K value Pour point rC]
2nd acrylate 50 C at RI M.
Amount of the additives
Mass Molar ratio [mm2/s] [g/mol] 100 300 1500
1
ratio ppm ppm ppm _
2-hydroxyethyl acrylate 7270
C4 90 / 10 75 / 25 237
39.5 18/12 12/12 1219
solid 98200
_
2-hydroxyethyl acrylate 7890
C5 57 /43 470 37.5
12/12 6/12 12/15 R
80 / 20 solid 79400
2
hydroxypropyl acrylate 6320
.
.=
06 90 / 10 79 / 21 212
40.3 9/12 6/6 6/12 w
solid 92800
..,
8
polypropylene glycol 5460
"
C7 90 / 10 92 / 8 245
39.5 9/9 6/6 9/9 L7,
monoacrylate solid 95760
.
A
,
polypropylene glycol - 6770
N
08 80/ 20 83 / 17 397
40.5 6/6 6/6 9/6 .
monoacrylate solid 174500
- 7055
09 C16/18-0-(E0)11 methacrylate 90/10 95/5 205
37.7 12/12 6/6 9/9
solid 107800
- 7225
010 C16/18-0-(E0)11 methacrylate 80/20 90/10 212
37.8 12/12 6/9 3/0
viscous 180100
- 8350
C11 phenoxyethyl acrylate 90/10 83/17 274
40.1 9/9 3/3 6/9
solid , 92500
Table 1 (cont.): Results of the examples and comparative examples
PF73680 CA 02889070 2015-04-20
The examples and comparative examples show that, with use of further alkyl
(meth)acrylates
(Al b) as well as behenyl acrylate, it is possible to obtain polymeric
compositions which are still
liquid in toluenic solution even as concentrates (48% by weight of polymeric
composition). The
5 polymer mixture comprising only behenyl acrylate is solid in toluenic
solution under the same
conditions.
However, not all alkyl (meth)acrylates are equally effective. Alkyl
(meth)acrylates having
branched alkyl radicals or those having relatively short, linear alkyl
radicals are effective.
10 The use of acrylates comprising OH groups or ether groups leads not to
liquid products but to
solid products. Equally, in the case of proportions of more than 50 mol% of
the monomers
(Al b), the performance properties of the polymer mixtures as pour point
depressants
deteriorate quite considerably. A polymeric composition comprising 73 mol% of
t-butyl acrylate
is liquid but is completely ineffective as a pour point depressant.
A quite excellent effect as a pour point depressant was obtained in experiment
19. The polymer
was prepared using a monomer mixture of 75% by weight of behenyl acrylate and
25% by
weight of cyclohexyl methacrylate.
