Note: Descriptions are shown in the official language in which they were submitted.
1323~
The invention relates to a composition containing a
partially hydrogenated block copolymer comprising at least
two terminal polymer blocks A o~ a monoalkenyl arene having
an average molecular weight of rrom 5,000 to 125,000 and
at least one intermediate polymer block B of a conjugated
diene having an average molecular weight of from 10~000 to
300,000~ in which the terminal polymer blocks A constitute
from 8 to 55% by weight of the block copolymer and no more
than 25% o~ the arene double bonds of the polymer blocks A
and at least 80% of the aliphatic double bonds o~ the
polymer blocks B have been reduced by hydrogenation.
Engineering thermoplastic resins are a group of polymers
that possess a balance of properties comprising strength,~
stirfness, impact resistance~ and long term dimensional
stability that make them useful as structural materials.
Engineering thermoplastic resins are especially attractive
as replacements for metals because of the reduction in
weight that can often be achieved as, ror example, in
automotive applicationsO
For a particular application, a single thermoplastic
resin may not offer the combination of properties de8ired
and, thererore, means to correct this deficiency are of
interest. One particularly appealing route is through
blending together two or more polymers tWhich individually
have the properties sought~ to give a material with the
desired combination of properties. ~his approach has been
... . . . ,_ .. , . .. . , , , ~
-3-
successful in limited cases, such as in the improvement
of impact resistance for thermoplastic resins, e.g. 9
polystyrene, polypropylene and poly(vinyl chloride),
using special blending procedures or additives for this
purpose. However, in general, blending of thermoplastic
resins has not been a successful route to enable one to
combine into a single material the desirable individual
characteristics of two or more polymers. Instead, it has
often been found that such blending results in combining
the worst features of each with the result bein~ a
material Or such poor properties as not to be of any
; practical or commercial value. The reasons for this
failure are rather well understood and stem in part from
the fact that thermodynamics te~ches that most combinations
of polymer pairs are not miscible, although a number of
notable exceptions are known. More importantly, most
polymers adhere poorly to one another. As a result, the
interfaces between componenk domains (a result of their
immiscibility) represent areas of severe weakness in blends
and, thereforel provide natural flaws and cracks which
result in facile mechanical failure. Because of this,
most polymer pairs are said to be "incompatible". In some
instances the term compatibility is used synonymously
with miscibility, however, compatibility ls used here in
a more general way that describes the ability to combine
two polymers together for beneficial results and may or
may not connote miscibility.
3~
-Ll_
One method which may be used to circumvent this
problem in polymer blends is to "compatibilize" the two
polymers by blending in a third component, often referred
to as a "compatibilizing agent", that possesses a dual
solubility nature for the two polymers to be blended.
Examples Or this third component are obtained in block
or graft copolymers. As a result Or this characteristic,
this agent locates at the interface between components
and grea~ly improves interphase adhesion and therefore
increases stabil:ity to gross phase separation.
The invention covers a means to stabilize multi-
polymer blends that is independent of the prior art
compatibilizing process and is not restricted to the
necessity for restrictive dual solubil:ity characteristics.
The materials used for this purpose are special block co-
polymers capable of thermally reversible self-cross linking.
~heir action in the present invention i5 not that visuali~ed
by the usual compatibilizlng concept as evidenced by the
general ability of these mate~ials to perform similarly
for a wide range of blend components which do not conform
to the solubility requirements of the previous concept.
Now, the invention provides a composition containing
a partially hydrogenated block copolymer comprising at
least two terminal polymer blocks A o~ a monoalkenyl arene
having an average molecular weight Or from 5,000 to 125,000,
and at least one intermediate polymer block B of a con-
jugatecl diene having an average molecular weight of from 10,000 to 300,000,
in which the terminal polymer blocks A constitute from 8 to 55% by weight
of the block copolymer and no more than 25% of the arene double bonds of the
polymer blocks A and at least 80% of the aliphatic double bonds of the
polymer blocks B have been reduced by hydrogenation, which composition is
characterized in that the composition comprises:
~a) 4 to 40 parts by weight of the partially hydrogenated block
copolymer;
(b) an acetal resin having a generally crystalline structure and a melting
point over 120C;
(c) 5 to 48 parts by weight of at least one dissimilar engineering
thermoplastic resin being selected from the group consisting of polyamides, : ;
polyolefins, thermoplastic polyesters, poly(aryl ethers), poly(aryl sulphones~
polycarbonates, thermoplastic polyurethanes, halogenated thermoplastics, and
nitrile resins,
in which the weight ratio of the acetal resin to the dissimilar engineering
thermoplastic resin is greater than 1:1 so as to form a polyblend wherein at
least two of the polymers form at least partial continuous interlocked
networks with each other.
In another aspect, the invention provides a process for the
preparation of a composition as claimed above characterized in that
(a) 4 to 40 parts by weight of a partially hydrogenated block copolymer
comprising at least two terminal polymer blocks A of a monoalkenyl arene
having an average molecular weight of from 5,000 to 125,000, and at least one
intermediate polymer block B of a conjugated diene having an average molecular
weight of from 10,000 to 300,000, in which the terminal polymer blocks A
constitute from 8 to 55% by weight of the block copolymer and no more than
25% of the arene double bonds of the polymer blocks A and at least 80% of
the aliphatic double bonds of the polymer blocks B have been reduced by
hydrogenation, are mixed at a processing temp0rature ~p of between 150C and
400C with
(b) an acetal resin having a generally crystalline structure and a
-- 5
J
.~
melting point over 120C, and
(c) 5 to 4~ parts by weight of at least one dissimilar engineering
thermoplastic resin being selected from the group consisting of polyamides,
polyolefins, thermoplastic polyesters, poly(aryl ethers), poly~aryl sulphones),
polycarbonates, thermoplastic polyurethanes, halogenated thermoplastics
and nitrile resins, in which the weight ratio of the acetal resin to the
dissimilar engineering thermoplastic resin is greater than 1:1, so as to
form a polyblend wherein at least two of the polymers form at least partial
continuous interlocked networks with each other.
The block copolymer of the invention ef~ectively acts as a mechanical
or structural stabili~er which interlocks
., .
- 5a -
,,
~JJ
~9~23
the various polymer structure networks and prevents the
consequent separation of the polymers during processing
and their subsequent use. As defined more fully herein-
after, the resulting structure of the polyblend (short
for "polymer blend") is that Or at least two partial
continuous interlocking networks. This interlocked
structure resu]ts in a dimensionally stable polyblend
that wil] not delaminate upon extrusion and subsequent
use.
To produce stable blends it is necessary that at
least two Or the polymers have at least partial continuous
networks which interlock with each other. Preferably~ the
block copolymer and at least one other polymer have partial
continuous interlocking network structures. In an ideal~
situation all of the polymers would have complete con-
tinuous networks which interlock with each other. A
partial continuous network means that a portion of the
polymer has a continuous network phase structure while
the other portion has a disperse phase structure. Prefer-
~
ably, a major proportion (greater than 50% by weight) o~the partial continuous network is continuous. As can be
readily seen, a large variety Or blend structures is
possible since the structure of the polymer in the blend
may be completely continuous, completely disperse 9 or
partially continuous and partially dispexse. Further yet,
the disperse phase of one polymer may be dispersed in a
-7~
second polymer an~] not in a third polymer. To illustrate
some of the structures, the following lists the various
combinations of polymer struc-tures possible where all
structures are complete as opposed to partial structures.
Three polymers (A, B and C) are involved. The subscript
"c" signifies a continuous structure while the subscript
"d" signifies a disperse structure. Thus, the designation
"QcB" means that polymer A is continuous with polymer B,
and the designation "BdC" means that polymer B is disperse
in polymer C, etc.
AcB AcC BcC
AdB AcC BcC
AcB AcC BdC
BdA AcC BcC
BdC AcB ACC
CdA AcB AcC
CdB AcB AcC
Th~ ice o~ the invention, it is possiOle
.. . .. .. ..
-7a~ %3~
to improve one ~ype of physical property of the composite
bl.end while not causing a significant deterioration in
another physical property. In the past this has not always
been possible. ~'or example, in the past it was expected
that by adding an amorphous rubber such as an ethylene-
propylene rubber to a thermoplastic polymer to improve
impact strengthg one would necessarily obtain a composite
blend having a significantly reduced heat distortion
temperature (HDT). This results from the fact that the
amorphous rubber forms discrete particles in the
composite and the rubber, almost by definition, has an
exceedingly low HDT, around room temperature. However,
in the present invention it is possible to significantly
improve impact strength while not detracting from the
heat di.stortion temperature. In fact, when the relative
increase in Izod impact strength is measured against the
relative decrease in HDT, the value of the ratio is much
higher than one would expect. For example, in blends
containing a polyacetal, block copolymer, and other
engineering thermoplastics such as PBT and polycarbonates,
this ratio is greater than 10~ whereas one would typically
expect positive values of less than 1.
- _ :
, ., . .. ,,, . . , .... , _ ... .
It is particularly surprising that even just small
amounts of the block copolymer are sufficient to stabillze
the structure of the polymer blend over very wide relative
concentrations. ~or example, as little as four parts by
weight of the block copolymer is sufricient to stabilize
a blend of 5 to 90 parts by weight polvacetal with 90 to
5 parts by weight of a dissimilar engineering thermoplastic.
In addition, it is also surprising that the block co-
polymers are US~ f`ul in stabilizing polymers of such a wide
variety and chemical make-up. As explained more fully
hereinafter, the block copolymers have this ability to
stabilize a wide variety o~ polymer over a wide range Or
concentrations since they are oxidatively stable a possess
essentially an infinite viscosity at ~ero shear stress,
and retain network or domain structure in the melt.
Another significant aspect of the invention is that
the ease of processing and ~orming the various polyblends
is greatly improved by employing the block copolymers as
stabilizers.
The block copolymers employed in the composition
according to the invention may have a variety o~ geometrical
structure, since the invention does not depend on any
specific geometrical structure, but rather upon the
chemical constitution of each of the polymer blocks. Thus3
the block copolymers may be llnear, radial or branched.
Methods for the preparation of such polymers are known in
~ 8~
g :
the art. The structure of the polymers is determined by
their methods of polymerization. For example, linear
polymers result by sequential introduction of the
desired monomers into the reaction vessel when using
such initiators as lithium-alkyls or dilithio-stilbene,
or by coupling a two-segment block copolymer with a
difunctional coupling agent. Branched structures,on the
other ~and, may be obtained by the use Or suitable
coupling agents having a functionality with respect to
the precursor polymers of' three or more. Coupling may be
effected with multifunctional coupling agents, such as
dihaloalkanes or -alkenes and divinyl benzene as well as
certain polar compounds, such as silicon halides, siloxanes
or esters of monohydric alcohols with carboxylic acids.
The presence of any coupling residues in the polymer may
be ignored for an adequate description of the polymers
forming a part Or the compositions of thls invention.
Likewise, in the generic sense, the specific structures
also may be ignored. The invention applies especially
to the use of selectively hydrogenated polymers having
the configuration before hydrogenation o~ the following
typical. species:
polystyrene-polybutadiene-polystyrene (S~S)
polystyrene~polyisoprene-polystyrene ~SIS)
poly(alpha-methylstyrene)polybutadiene-
poly(alpha-methylstyrene) and
~13231
-10-
poly(alpha-methylstyrene)polyisoprene-
poly(alpha-methylstyrene).
Both polymer blocks A and B may be either homopolymer
or rando~ copolymer blocks as long as each polymer block
predominates in at least one class o~ the monomers charac
terlzing the polymer blocks. The polymer block A may
comprise homopolymers of a monoalkenyl arene and co-
polymers of a monoalkenyl arene with a conjugated dlene
as long as the polymer blocks A individually predomlnate
in monoalken~l arene units. ~he term l'monoalkenyl arene"
; will be taken to include especially styrene and its
analogues and homologues including alpha-methylstyrene
and ring-substituted styrenes, particularly`ring-methyl-
ated styrenes. The preferred monoalkenyl arenes are
styrene and alpha-methylstyrene, and styrene is
particularly preferred. The polymer bLocks B may comprise
homopo]ymers of a conjugated diene, such as butadiene or
isoprene~ and copolymers of a conjugated diene with a
monoalkenyl arene as long as the polymer blocks B pre-
dominate in conjugated diene units. When the monomeremployed is butadiene, it is preferr~d that between 35
and 55 mol. per cent of the condensed butadiene units in
the butadiene polymer block have 1,2-configuration. Thus~
when such a block is hydrogenated, the resulting product
is, or resembles, a regular copolymer block of ethylene
and butene-1 (EB). If the conjugated diene employed is
~S3~ 3~
isoprene, the resulting hydrogenated product is or
resembles a regular copolymer block of ethylene and
propylene (EP~.
Hydrogenation o~ the precursor block copolymers is
preferably efrected by use Or a catalyst comprising the
reaction products of an aluminîum alk~l compound with
; nickel or cobalt carboxylates or alkoxides under such
conditions as to substantially completely hydrogenate
at least 80% of` the aliphatic double bonds, while
hydrogenating no rnore than 25% of the alkenyl arene
aromatic double bonds. Preferred block copolymers are
those where at least 99~ o~ the aliphatic double bonds
are hydrogenated while less -than 5% of the aromatic
double bonds are hydrogenated.
The average molecular weights of the individual
blocks may vary within certain limits. The block co-
polymer present in the composition according to the
invention has at least two terminal polymer blocks A of
a monoalkenyl arene having a number average molecular
weight of from 5,000 to 125,000, preferably from 7,000
to 60,0007 and at least one interrnediate polymer block B
of a conjugated diene having a number average molecular
weight of from 10,000 to 300,000, preferably from 30,000
to 150,000. These molecular weights are most accurately
determined by tritiurn counting methods or osmotic pressure
measurement s .
~Y18;~3~
-12-
The proportion of the polymer blocks A of the mono-
alkenyl arene should be between 8 and 55% by weight of
the block copolymer, preferably between 10 and 30% by
w~v~
.. , . , .. . . _ . ~ . . . .......... . ..... . . .
~13-
The acetal resins present in the.com-
positions according to the invention include the high
molecular weight polyacetal. homopolymers made by polymer-
izing formaldehyde or trioxane. These polyacetal homo- :
polymers are commercially available under the trade ~ffl~
DELRIN ~f. A related polyether-type resin is available ~:
~0~
under the trade ~ PENTON ~ and has the structure: :
_ ~ .
CH2C1 ,
_ _o C112 C--C~12- ~'
; :
n
The acetal resin prepared frorn formaldehyde has a high
molecular weigh~ and a structure typified by the following:
'~
- H- O- ( C'H~- O -CH2- O) ~ -H
where terminal groups are derived from controlled amounts Or ~ ~;
water and the x denotes a large ~prererably ~500) number Or ~-
formaldehyde units linked in ~lead~to-tail fashion. To in-
crease thermal and chemical resistance, terminal groups :~ :
are typically converted to esters or ethers. . ~`
Also included :in the term polyacetal resins are the
polyacetal copolymers. These copolymers include block co- ~ :
po].ymers of formaldehyde with monomers or prepolymers Or
other materials capable of providing active hydrogens,
3;23~ -
1 Ll -
such as alkylene glycols, polythio]s, vinyl acetate-
acrylic acid copolymers, or reduced butadiene/acrylonitrile
polymers.
~ Celanese has commercially available a copolymer of
5 ~ formaldehyde and ethylene oxide under the trade ~me CELCON
that is useful in the blends of the present invention. ~hese
copolymers typically have a structure comprising recurring
units having the formula:
_Lo
wherein each R1 and R2 is selected from the group consisting
; 10 of hydrogen, lower alkyl and lower halogen substituted
alkyl radicals and wherein n is an integer from zero to t~lree
and wherein n is zero in from 85% to 99.9% of the recurrln
units.
Formaldehyde and trioxane can be copolymerized with
other aldehydes, cyclic ethers, vinyl compounds, ketenes,
cyclic carbonates, epoxides, isocyanates and ethers. These
compounds include ethylene oxide, 1,3-dioxolane, 1,3-dioxane,
1,3-dioxepene, epichlorohydrin, propylene oxide, isobutylene
oxide, and styrene oxide.
15-
- ili~l~;~38
The term "dissimilar engineering thermoplastic resin"
refers to engineering thermoplastic resins different from
those encompassed by the polyacetals present in the com-
positions according to the invention.
The term "engineering thermoplastic resin" encompasses
the various polymers found in the classes listed in Table A
below and thereafter defined in the specification.
TABLE A
1. Polyolefins
2. Thermoplastic polyesters
3. Poly(aryl ethers) and poly(aryl sulphones)
4. Polycarbonates
5. Polyamides ;
6. Thermoplastic polyurethanes
7. Halogenated thermoplastics
8. Nitrile resins
Preferably these engineering thermoplastic resins
have glass transition temperatures or apparent crystalline
melting points (defined as that temperature at which the
modulus, at low stress, shows a catastrophic drop) of -~
o~er 120C, preferably between 150C and 350C, and are
capable of forming a continuous network structure
through a thermally reversible cross-linking mechanismO
Such thermally reversible cross-linking mechanisms in-
clude crystallites, polar aggregations, ionic aggregations,
lamellae, or hydrogen bonding. In a specific embodiment~
-16-
3~
where the viscosity of the block copolymer or blended
block copolymer composition at processing temperature Tp
and a shear rate of 100 s 1 is n, the ratio of the
viscosity of the engineering thermoplastic resins, or
blend of engineering thermoplastic resin with viscosity
modifiers to ~ may be between 0.2 and 4.0, preferably 0.8
and 1.2. As used in the specification and claims3 the
viscosi-ty of the block copolymer, polyacetal and the
thermoplastic engineering resin is the "melt viscosity"
obtained by employing a piston-driven capillary melt
rheometer at constant shear rate and at some consistent
temperature above melting, say 260C. The upper limit
(350C) on apparent crystalline melting point or glass
transition temperature is set so that the resin may be
procesaed in low to medium shear rate equipment at com-
mercial temperature levels of 350C or less.
The engineering thermoplastic resin includes also
blends of various engineering thermoplast;ic resins and
blends with additional viscosity modifying resins.
These various classes of engineering thermoplastics
are defined below.
The polyolefins~ if present in the compositions ac-
cording to the invention are crystalline or crystallizable.
They may be homopolymers or copolymers and may be derived
from an alpha-olefin or 1-olefin having 2 to 5 carbon
atoms. Examples of particular useful polyolefins include
-17-
,, ~
low-density polyethylene~ high-~ensity polyethylene, iso-
tactic polypropylene, poly(1-butene)~ poly(4-methyl-1-
pentene), and copolymers of Ll-methyl-1-pentene wlth
linear or branched alpha--olefins. A crystalline or
crystallizable structure is important in order for the
polymer to be capable of forming a continuous structure
with the other polymers in the polymer blend according
to the invention. The number average molecular weight of
the polyolefins may be above 10,000, preferably above 50,000.
In addition, the apparent crystalline melting point may be
above 100C, preferably between 100 C and 250C, and more
preferably between 140C and 250C. The preparationsof
these various polyolefins are well known. See generally
"Olefin Polymers", Volume 14, l~irk-Othmer Encyclopedia of
Chemical Technology, pages 217-335 (1967)~
When a high-density polyethylene is employed, it has
a- ~I r~ crystallinity of over 75~ and a density in
~ : -
`'`` ~. \ ' :
~ 3
-18-
kilograms per litre (kg/l) of between 0.9ll and 1.0 while
when a low density polyethylene is employed, it has an
approximate crystallinity of over 35% and a density Or
between 0.90 kg/l and 0 94 kg/l. The composition ac-
cording to the invention may contain a polyethylene havinga number average molecular wei~ht of 50,000 to 500,000.
When a polypropylene is employed, it is the sa-
called isotactic polypropylene as opposed to atactic
polypropylene. The number ~verage molecular weight Or the
polypropyle~ne erl~ploye(lr~Y~eineXcess Or loo,ooo. The ~oly-
propylene may b~ prepared using methods of the prior
art. Depending on the specific catalyst and polymer- -
i~ation conditions employed, the polymer produced may
contain atactic as well as isotactic~ syndiotactic or
so-called stereo-block molecules. These may be separated
by selective solvent extraction to yield products o~
low atactic content that crystalliæe mo~e completely.
The preferred cornrnercia] polypropylenes are generally
prepared using a solid~ crystalline, hydrocarbon-in-
soluble catalyst made from a titanium trichloride com-
position and an aluminium alkyl compound, e.g., tri-
ethyl aluminium or diethyl aluminiurn chloride. If
desired, the polypropylene employed is a copolymer
containing rninor (1 to 20 per cent by weight) amounts
Or ethy]ene or another alpha-olefin as comorlomer.
3~323~
The poly(l-butene~ preferably has an isotactic structure.
The c talysts used in preparing the poly(l-butene) are
preferably organo-metallic compounds commonly referred to .
as Ziegler--Natta catalysts. A typical catalyst is the
interacted product resulting from mixing equimalar quan-
tities of titanium tetrachloride and triethylaluminium.
The manufacturing process is normally carried out in an
inert diluent such as hexane. Manufacturing operations,
in all phases of polymer rormation~ are conducted in such
a manner as to guarantee rigorous excluslon of water even
in trace amounts.
One very suitable polyolefin is poly(4-methyl-1-pentene).
Poly(4-methyl-1-pentene) has an apparent crystalline melt-
ing point of between 240 and 250 C and a relative density
f between 0.80 and 0.85. Monomeric 4-nlethyl-1-pentene is
commercially manufactured by the alkali-metal catalyzed
dimer:ization of propylene. The homopolymerization Or
4-methyl-1-pentene with Ziegler-Natta catalysts is descrlbed
in the Kirk-Othmer Enclopedla Or Chemical Technology~
Supplement volume, pages 789-792 (second edition, ly7
However, the isotactic homopolymer Or 4 methyl-l-pentene
has certain technical derects, such as brittleness and~ ~ -
inadequate transparency. Therefore, commercially available
poly(4-rnethyl-1-penterle) is actually a copolymer with -
minor proportions of other alpha-olefins, together with
the addition Or suitable oxidation and melt stabilizer
......... . .. ... . ..... .. . . ..
3~
-~o-
systems. These copolymers are described in the Kirk-
Othmer Encyclopeclia of Chemical Tecynology, Supplement
volume~ pages 792-907 (second edition, 1971)~ and are
~ available under the trade ~ TPX~ resin. Typical
alpha-olefins are linear alpha-olefins having from 4
to 18 carbon atoms. Suitable resins are copolymers of
4-methyl-1-pentene with from 0.5 to 30% by weight of a
linear alpha-olefin.
If desiredg the polyolefin is a mixture of various
polyolefins. However, the much preferred polyolefin is
isotactic polypropylene.
The thermoplastic polyesters~ if present in the com-
positions according to the invention, have a generally
crystalline structure, a melting point over 120C, and
are thermoplastic as opposed to thermosetting.
3~
-21-
One particularly useful group of polyesters are those
thermoplastic polyesters prepared by condensing a di
carboxylic acid or the lower alkyl ester, acid halide~
or anhydride derivatives thereo~ with a glycol, according
to methods well known in -the art.
Among the aromatic and aliphatic dicarboxylic acids
sui.table for preparing polyesters are oxalic acid, malonic
acid, succinic acid, g]utaric acid, adipic acid, suberic
acid, azelaic acid, sebacic acid, terephthalic acid, iso-
phthalic acid, p carboxyphenoacetic acid, p,p'~icarboxydiphenyl,
p~pl-dicarboxydiphenylsulphone, p-carboxyphenoxyacetic acid,
p-carboxyphenoxypropionic acid, p-carboxyphenoxybutyric acid,
p carboxyphenoxyvaleric acid, p-carboxyphenoxyhexanolc acid~, -
p,~'-dlcarboxydiphenylmethane, p~p-dicarboxydiphenylpropane,
p,p'-dicarboxydiphenyloctane, 3~alkyl-4-(~-carboxyethoxy)-
benzoic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-
naphthalene dicarboxylic acid. Mixtures Or dicarboxylic
acids can also be employed. Terephthalic acid is particularly
preferred.
The glycols suitable ~or preparing the polyesters
include straight-chain alkylene glycols of 2 to 12 carbon
atoms, such as ethylene glycol, 1,3 propylene glycol,
1,6-hexylene glycol, l,10-decamethylene glycol, and 1,12-
dodecameth~lene glycol. Aromatic glycols can be substituted
in whole or in part. Suitable aromatic dihydroxy compounds
include p-xylylene glycoll pyrocatechol, resorcinol,
8238
-22-
hydroquinone, or alkyl-substituted derivatives of these
compounds. Another suitable glycol is 1,4-cyclohexane
dimethanol. Much preferred glycols are ~e straight-chain
alkylene glycols having 2 to 4 carbon atoms.
A preferred group of po:Lyesters are poly(ethylene
terephthalate), poly(propylene terephthalate), and poly-
(butylene terephthalate). A much preferred polyester is
poly(butylene terephthalate). Poly(butylene terephthalate)j
a crystalline copolymer, may be formed by the po]ycondensatlon
of` l,ll-butanediol and dimethyl t-rephtha]ate or terephthalic
acid, and has the generalized formula:
~C--~,3--C--O--~C~
n
where n varies lro~ 70 to 140. The average molecular weight
of the poly(butylene terephthalate) preferably varies from
20,000 to 25,000.
Commercially available poly(butylene terephthalate) is
~Of~
D available under the trade ~ VALOX~ thermoplastic
polyester. Other commercial polymers include CELANEX
TENITE ~ and VITUF ~ .
Other useful polyesters include the cellulosic esters.
The thermoplastic cellulosic esters employed herein are -
widely used as mouldin~, coatin~ and film forming materials
.. . ..... .. _ _ _ . .... ......
and are well known. These materials include the solid
thermoplastic forms Or cellulose nitrate, cellulose
acetate (e.g., cellulose diacetate, cellulose tri-
acetate), cellulose butyrate, cellulose acetate butyrate,
cellulose propionate, cellulose tridecanoate, carboxy
methyl cellulose, ethyl cellulose, hydroxyethyl cellulose
and acetylated hydroxyethyl cellulose as described on
pages 25-28 of Modern Plastics Encyclopedia~ 1971-72, and
references listed therein.
Another useful polyester is a polypivalolactone. Poly-
pivalolactone is a linear polymer having recurring ester
structural units ~ainly Or the formula:
- -CH C(CH ~ -C(0)0 -
i.e., units derived from pivalolactone. Preferably, the poly-
ester is a pivalolactone homopolymer. Also included~ however,~are the copolymers of pivalolactone with no more than 50 mo].~,
preferably not more than 10 mol.% of another beta-propio-
lactone, such as beta-propiolactone, alpha,alpha-diethyl-
beta-propiolactone and alpha-methyl-alpha-ethyl-beta-propio-
lactone. The term "heta-propiolactones" re~ers to beta-
propiolactone (2-oxetanone) and to derivatives thereof which
carry no substituents at the beta-carbon atom of the lactone
ring. Preferred beta-propiolactones are those containing a
tertiary or quaternary carbon atom in the alpha-position
relative to the carbonyl group. ~specially pre~erred are the
alpha,alpha-dialkyl-beta-propiolactones wherein each of the
alkyl groups independently has from one to four carbon atoms.
38
-24-
. .
Examples of useful monorners are:
alpha ethyl-alpha-methyl-beta-propio:Lactone,
alpha-methyl-alpha-isopropyl-beta-propiolactone~
alpha-ethyl-alpha-n-butyl-beta-propiolactone,
alpha-chloro~ethyl-alpha-methyl-beta-propiolactone,
alpha~alpha-bls(chloromethyl)-beta-propiolactone, and
alpha,alpha-dimethyl-beta-propiolactone (pivalolactone).
These polypivalolactones have an average molecular weight in
excess of 20,000 and a melting point in excess of 120C.
Another useful polyester is a polycaprolactone.
Preferred poly(~-caprolactones) are substantially linear
polymers in which the repeating unit is~
O ~ ~ .
t CH2 c~12 CH2 CH2_CH2 c ~
These polymers have similar properties to the polypivalo-
lactones and may be prepared by a similar polymerization
mechanism.
Various polyaryl polyethers are also useful as en~ineer-
ing thermoplastic resins. The poly(aryl polyethers) which
may be present in the composition according to the invention
include the linear thermoplastic polymers composed of re-
curring units having the formula:
(o - a - o - G'~
wherein Gisthe residuum of a dihydric phenol selected from
the group consisting of:
323~
-25-
and
- ~ R~ ~ 3 III
wherein R represents a bond between aromatic carbon atoms, ~.
O , S , S- s-,or a divalent hydrocarbon radical
having ~rom 1 to 18 carbon atoms inclusive, and G' i5 the
residuum of a dibro~no or di-iodobenzenoid compound
selected ~rom the group consistine Or:
~ IV
and
_~_p~,~3 V ~' ~
wherein R' represents a bond between aromatic carbon atoms,
- O- , - S , -S- S ,or a divalent hydrocarbon `
radical having from 1 to 18 carbon atoms inclusive, with
the provlsions tha-t when R is - O - , R' is other than
O ; when R' is - O - , R is other than - O - ;
when G is II, C' is V, and when G' is IV, G is III.
.
... . .. , ........... . __~_, _
~3 ~ 2~ ~ ;
-26-
Polyarylene polyethers of this type exhibit excellent physical
properties as well as excellent thermal oxidative and
chemical stability. Commercia]. poly(aryl polyethers) are
~ available under the trade ~R~ ARYLON T ~ Polyaryl ethers~
having a melt temperature of between 280C and 310C.
Another group of useful engineering thermoplastic
resins include aromatic poly(sulphones) comprising re~
peating units of the formula:
Ar S0
in which Ar is a bivalent aromatic radical and may vary ~ ~ ;
from unit to unit in the polymer chain (so as to I'orm co~
polymers o~ various kinds~. Thermoplastic poly(sulphones) :
generally have at least some units of the structure:
SO2
.
in which Z is oxygen or sulphur or the residue of an
aromatic diol, such as a 4,4'-bisphenol. One example of
such a poly(sulphone) has repeating units of the ~ormula:
~3----/~SO2
2~
-27- :
another has repeating uni.ts Or the formula:
~ s~o2- ~
and others have repeating units of the formula:
~3 S2 ~ - ~ ~ ~/ 3 - O - ;~
3 ~ :~
or copolymeri.zed units ;.n various proportions of the
~ormula:
~ 2
and
O
'
~ '
The thermoplastic poly(sulphones? may also have repeating
units having the formula:
~,/~ ~ - ~ S2
Poly(ether sulphones) having repeating units Or the
following structure:
3~
-28-
t/~3 ~3 1 n
and poly(ether sulphones) having repeating units of the
following structure:
~3so2 ~ c~l3~-L
C~13 ~ ~ `
_ n ~ ~;
:~ '
are also useful as engineering thermoplast:ic resLn~
The polycarbonates which may be present in the com-
positions accordlng to the invention are of the general
formulae:
o
--~Ar- A- Ar- O - C - 0~
n
and
- ~Ar --O - C -0~
wherein Ar represents a phenylene or an alkyl, alkoxy, -
halogen or nitro-substituted phenylene group; A represents
a carbon-to-carbon bond or an alkylidene, cycloalkylidene,
alkylene, cycloalkylene, azo, imino, sulphur, oxygen,
sulphoxide or sulphone group~ and n is at least two.
32~
-29-
The preparation of the polycarbonates i5 well known.
A preferred method of preparation is based on the reaction
carried out by dissolving the dihydroxy component in a
base, such as pyridine and bubbling phosgene into the
stirred solution at the desired rate. Tertiary amines may
be used to catalyze the reaction as well as to act as acid
acceptors throughout the reaction. Since the reaction is
normally exothermic, the rate of phosgene addition can be
used to control the reaction temperature. The reactions
generally utilize equimolar amounts of phosgene and di~
hydroxy reactants, however, thé molar ratios can be varied
dependent upon the reaction conditions.
In the formulae I and II mentioned, Ar and A are,
preferably, p-phenylene and isopropylidene~ respectively.
This polycarbonate is prepared by ~el~ct;ng para,para'iso-
propylidenediphenol with phosgene and is sold under the
trade mark LEXAN ~ and under the trade mark MERLON
This commercial polycarbonate ha~ a molecular weight o~
around 18,000, and a melt temperature o~ over 230C.
Other polycarbonates may be prepared by reactin~ other
dihydroxy compounds~ or mixtures Or dihydroxy compounds~
with phosgene. The dihydroxy compounds may include aliphatic
dihydroxy compounds although for best high temperature
properties aromatic rings are essential. The dihydroxy
compounds may include within the structure diurethane
linkages. Also, part Or the structure may be replaced by
siloxane linkage.
;23~
By polyamide is meant a condensat:ion product which
contains recurring aromatic and/or aliphatic amide groups
as intc~ral parts of the main polymer chain, such products
being known generi.cally as "nylonsl'. A polyamide may be
obtained by polymerizing a mono-aminomonocarboxylic acid
or an internal lactam thereof having at least two carbon
atoms between the amino and carboxylic acid groups, or
by polymerizing substantially equimolar proportions of a
diamine which contains at least two carbon atoms between
the amino groups and a dicarboxylic acid, or by polymer-
izing a mono-aminocarboxylic acid or an internal lactam
thereof as defined above together with substantially equi-
molar proportions of a diamine and a dicarboxylic acid.
The dicarboxylic acid may be used in the form of a functional
derivative thereof, for example an ester.
~ he term "substantially equimolecular proportions"
(of the diamine and of the dicarboxylic acid) is used to
cover both strict equimolecular proportions and the slight
departu~e~ r^~rom which are involved in conventional
, ,
~ :,
. .. ... . _ .". ~ . _ . _ .. __, _. . . ....
~ 3 ~
-31-
techniques for stabili~ing the viscosity of the resultant
polyamides.
As examp]es Or the said mono-aminomonocarboxylic acids
or lactams thereof there may be mentioned those compounds
containing from 2 to 16 carbon atoms between the amino and
carboxylic acid groups, said carbon atoms forming a ring
with the CO.NH - group in the case of a lactam. As
particular examples of aminocarboxylic acids and lactams
there may be mentioned ~-aminocaproic acid, butyrolactam,
pivalolactam, caprolactam~ capryl-lactam, enantholactam,
undecanolactam, dodecanolactam and 3- and 4-amino benzoic
acids.
Examples of the said diamines are diamines Or the
general f`ormula ~I~N(CH2)nNH2, ~herein n is an integer of
from 2 to 16, such as trimethylenediamine, tetramethylene-
diamine, pentamethylenediamine, octamethylenediamine,
decamethylenediamine, dodecamethylenediamine, hexadeca-
methylenediamine, and especially hexamethylenediamine~
C-alkylated diamines, e.g~, 2,2-dimethylpentamethylene-
diamine and 2,2,4-and 2,4,4-trimethylhexamethylenediamine
are further examples. Other diamines which may be mentioned
as examples are aromatic diamines, e.g., p~phenylene-
diamine~ 4,4'-diaminodiphenyl sulphone, 4,4'wdiaminodi
phenyl ether and 4,ll'-diaminodiphenyl sulphone, 4,4'-di-
aminodlphenyl ether and 4,ll'-diaminodiphenylmethane; and
cycloaliphatic diamines, for example diaminodicyclohexyl-
methane.
-32-
I'he said dicarboxylic acids may be aromatic, for
example isophthalic and terephthalic acids. Preferred
dicarboxylic acids are of the rormula HOOC.Y.COOH,
wherein Y represents a divalent aliphatic radical
containing at least 2 carbon atoms~ and examples of
such acids are sebacic acid, octadecanedi~c acid~
suberic acid, azelaic acid, undecanedioic acid, glutaric -~
acid, pimelic acid, and especially adipic acid. Oxalic
acid is also a preferred acid.
Specirically the :rollowing polyamides may be in-
corporated in the thermoplastic polymer blends of the
invention:
polyhexamethylene adi.pamide (nylon 6:6) -
polypyrrolidone (nylon 4)
polycaprolactam (nylon 6)
polyheptolactam (nylon 7)
~olycapryllactam (nylon 8)
polynonanolactam (nylon 9)
polyundecanolactam (nylon 11)
polydodecanolactam (nylon 12)
polyhexamethylene azelaiamide (nylon 6:9)
polyhexamethylene sebacamide (nylon 6:10)
polyhexamethylene i.sophthalamide (nylon 6:iP)
polymetaxyly].ene~ipamide (nylon MXD:6)
polyamide of hexamethylene diamine and n-dodecanedioic
acid (nylon 6:12)
3~
polyamide of dodecamethylenediamine and
n dodecanedioic aci.d (nylon 12:12).
Nylon copolymers may also be used, for example co-
polymers of the.following:
hexamethylene adlpamide/caprolactam (nylon 6:6/6)
hexamethylene adipamide/hexamethylene-isophthalamide
(nylon 6:6/6ip)
hexamethylene adipamide/hexamethylene-terephthalamide
(nylon 6:6/6T)
trimethylhexamethylene oxamide/hexamethylene oxamide
(nylon trlmethyl-6:2/6:2)
hexamethylene adipamide/he~amethylene-azelaiamide
(nylon 6:6/6:9)
hexamethylene adipamide/hexamethylene-azelaiamide/
caprolactam (nylon 6:6/6:9/6).
Also useful is nylon 6:3. This polyamide is the product
of the dimethyl ester of terephthalic acid and a mixture of
isomeric trimethyl hexamethylenediamine.
Pre.ferred nylons include nylon 6~6/6, 11, 12, 6/3
and 6/12.
~he number average molecular weights of the polyamides
may be above 10,000.
- 3 L~ 3~
Polyurethanes, o-therwise known as isocyanate resins,
also can be employed as engineering thermoplastic resin as
long as they are thermoplastic as opposed to thermosetting.
For example, polyurethanes formed from toluene di-iso-
cyanate (TDI) or diphenyl methane 4,4-di-isocyanate (MDI)
and a wide range of polyols, such as~ polyoxyethylene glycol,
polyoxypropylene glycol, hydroxy--terminated polyesters, poly-
oxyethylene-oxypropylene glycols are suitable.
These thermoplastic polyurethanes are available under
~ ,~C~r~ ~ ~
10 ~L~ the trade-~ Q-THANE~ and under the trade ~ffle-PELLETHANE ~ -
CPR.
Another group of useful engineering thermoplastics in~ -
clude those halogenated thermop]astics having an essentially
crystalline structure and a melt point in excess of 120C.
15 These halogenated thermoplastics include homopolymers and
copolymers derived from tetrafluoroethylene, chlorotrifluoro-
ethylene, bromotrifluoroethylene, vinylidene fluoride, and
vinylidene chloride.
Polytetrafluoroethylene (PTFE) is the name given to
20 fully fluorinated polymers of the basic chemical formula
2-~ - which contain 76% by weight fluorine.
` These polymers are highly crystalline and have a crystalline
. . . ~
,,. ~
~ ' ~ .
rnelting point of over 300C. Commercial P'l'FE is available
~ 0,~
urlder the traf1~ ~4 Tl~r~'L,ON ~ and undc~r the trade ~
li'LIJON ~ . Polych10rotr:irluoroethylene (PC'I'1~E) and poly-
: bromotrifluoroethylene (Pl3T~E) are also available in high
molecular welght~ and can be employed in the presenl; in-
verlt ion .
EGpecially preferred halogenated polymers are homo-
pol.ymers and copolymers of vinylidene fluoride. Poly
(vlnylidene fluori.de) homo~olymers are the ~arti.ally
:LO I'luor:irlated polymers ol` the chc~nlical formula -~--C~12--Cl~2-~.
These polylrler, are tou~rh :L.i.rlear E)o1ymers w.ith a cry<ta:l:l;.no
melting point at 170C. Commerc:ial homopolymer is ava.illt)].e
; under the trade ~K~ KYNAI~ ~ The tc~rm '~poly(v:i.nyliderle
I'luori.de)" as used here.in rcrer not nnly to the norma].1.y
so].id homopolymers of vinylidene fluoride, but also to the
normally soli.d copolymers of' v;.nylidene fluoride containin~
at least 50 mol.% of polymerized vlnylidene rluori~e unit~,
preferably at least 70 mol.% vinylidene rluoride and more
pref'erably at least 90 mol.%. Suitable comonomers are
halogenated olefins containing up to 4 carbon atoms, for
examp].e, sym. dichlorodifluoroethylene, vinyl fluoridej ~ .
vinyl chloride, viny].idene chloride, perfluoropropene,per-
rluorobutadiene, chlorotrirluoroethylene, trichloroethylene
and tetrafluoroethylene.
Another useful group Or halogenated thermoplastics
include homopolymers and copolymers derived from vinylidene
chloride~ Crystalline vi.nylidene chloride copolymers are
23~
: -~6-
especi.ally preferred. The normally crystal:l.ine vinylidene
chlorlde copolymers that are useful in the present in-
vention ar~ those contairling at least 70% ~y weight Or
vinylidene chloride together with 30% or less of a co-
polymerizable monoethylenic monomer. Exemplary of such
monomers are vinyl chlor;de7 v:inyl aceta.te, vinyl
propi.onate, acry:lonitril(;, alkyl and aralkyl acrylates
havirlg alky] and aralkyl groups Or up to about 8 carbon .
atoms, acryl.;.c ~lci(~, acrylam;.d(?, vinyl alkyl ethers,
vlnyl alkyl ketono.;, acrol.ein, a:l.l.yl ethers arld others,
butadi.ene and chloropror)ene~ Known tcrrlary compos.itiorls
also may be employed advarltageous.Ly. ]~epr~;orltntive Or
such polymers are those composed of` at least 70% by wei~ht
oI v;.nylidene chlori.de wi.t;h the remaill(ler made up oI, for
example, acrolei.n and vinyl chloride 3 acrylic acid an(l
acryloni.trile, alkyl acrylates and alkyl methacrylates, ~:
acrylonitri.le and butadielle, acrylonitril~ and i.taconic ~: -
acid, acrylonitrile and vinyl acetate, vinyl propionate
or vinyl chloride~ allyl esters or ethers and vinyl ;;
; 20 chloride, butadlene and vinyl acetate, vinyl propionate, :
~ or vinyl chloride and vinyl ethers and vinyl chloride.
; Quaternary polymers of sirnilar monomeric composition will
also be known. Particularly useful for the purposes
the present invention are copolymers o~ rrom 70 to 95% by
wei~ht vinylidene chloride with the balance being vinyl
chloride. ',uch copolymers may conta;.n conventional amounts
3~3
and types of plasticizers, stabilizers, nucleators and
extrusion aids. Further~ blends of two or more o~ such
normally crystalline vinylidene chloride polymers may
be used as well as blends comprising such normally
crystalline polymers in combinatiorl with other polymeric
modifiers~ e.g., the copolymers of ethylene-vinyl acetate,
styrene-maleic anhydride, styrene-acrylonitrile and poly-
ethylene.
The nitrile resins useful as engineering thermoplastic
resin are those thermoplastic materials having an alpha,beta-
; olerinically unsaturated mononitrile content Or 50% by
weight or greater. These nitrile resins may be homopolymers,
copolymers, grafts Or copolymers onto a rubbery substrate,
or blends of homopo]ymers and/or copolymers.
The alpha~beta-olefinically unsaturated mononitriles
encompassed herein have the structure
Cll2 C CN
R
where R is hydro~en, an alkyl group having from 1 to 4
carbon atoms~ or a halogen. Such compounds include acrylo-
nitrile, alpha~bromoacrylonitrile, alpha-~luoroacrylo-
ni-trile, methacrylonitrile and ethacrylonitrile. The most
preferred olefinically unsaturated nitriles are acrylo-
nitrile and methacrylonitrile and mixtures thereo~.
These nitrile resins may be divided into several
classes on the basis of cornplexity. The simplest molecular
.. .. ,~ . ......... .... . . .. ....... .... .. .
3~
-38-
structure is a random copolymerg predominantly acrylonitrile
or methacrylonitrile. The most common example is a
styrene-acrylonitrile copolymer. Block copolymers of
acrylonitrile, in which long segments of polyacrylonitrile
alternate with segments o~ polystyreneS or Or polymethyl
methacrylate, are also known.
Simultaneous polymerization of more than two co-
monomers produces an interpolymer, or in the case of
three components, a terpolymer. A large number of co-
monomers are known. These include alpha-olerins o~ from
2 to 8 carbon atoms 3 e.g. ethylene, propylene, iso-
butylene, butene-1~ pentene-1 and their halogen and
,
aliphatic substituted derivatives as represented by vinyl
chloride and vinylidcne chloride; monovinylidene aro~atic
hydrocarbon monomers o~ the general formula~
~12C~C,~
R~
wherein R1 is hydrogen chlorine or methyl and R2 is an
aromatic radical of 6 to 10 carbon atoms which may also
contain substituents~ such as halogen and alkyl groups
attached to the aromatic nucleus, e.g., styrene, alpha
methyl styrene, vinyl toluene, alpha-chlorostyrene, ortho-
chlorostyrene, para-chlorostyrene, meta-chlorostyrene,
ortho-methyl styrene, para-methyl styrene, ethyl styrene 5
~82~3~
.
~ 9
isopropyl styrene, dlchlorostyrene and vinyl naphthalene.
Especially preferred comonomers are isobutylene and styrene.
Another group of comonomers are vinyl ester monomers
of the general formula:
H
R3C=C
O
C=O
R3
wherein R~ i5 se]ected from the group comprising hydrogen,
alkyl groups of rrom 1 to 10 carbon atoms, aryl groups Or
from 6 to 10 carbon atoms lncluding the carbon atoms in
ring-substituted alkyl substituents; e.g.3 vinyl formate,
vinyl acetate, vinyl proplonate and vinyl benzoate.
10Similar to the foregoing and also useful are the
vinyl ether monomers of the general formula:
H2C-C~I 0 - R4
wherein R4 is an alkyl group of from 1 to 8 carbon atoms,
an aryl group of from 6 to 10 carbons, or a monovalent
aliphatic radical of from 2 to 10 carbon atoms, which
15aliphatic radical may be hydrocarbon or oxygen-containing, ~-
e.g.3 an aliphatic radical with ether linkages, and may
also contain other substituents, such as halogen and
carbonyl. Examples of these monomeric vinyl ethers include
vinyl methyl ether, vinyl ethyl ether3 vinyl n-butyl ether,
vinyl 2-chloroethyl ether, vinyl phenyl ether, vinyl iso-
..... , _ . . , .. , .. . .. . _ .. .. _ .. .... .
~: .
~8~8
- 1l o -
butyl ether, vinyl cyclohexyl ether, p-butyl cyclohexyl
ether, vinyl ether or p-chlorophenyl glycol.
Other comonomers are those comonomers which contain
a mono- or dinitrile functlon. Examples of these include
methylene glutaronitrile, (2,4-dicyanobutene-1), vinyl-
idene cyanide, crotonitrile, fumarodinitrile, maleodi- ~-
nitrile.
Other comonomers include the esters of olefinically
unsaturated carboxylic acids,preferably the lower alkyl
esters of alpha,beta-olefinically unsaturated carboxylic
acids and more preIerred the esters having the structure~
CH2 = C COOR2
wherein Rl is hydrogen, an alkyl group having from 1 to 4
carbon atoms, or a halogen and R2 is an alkyl group hav;ng
from 1 to 2 carbon atoms. Compounds Or this type include
methyl acrylate, ethyl acrylate, methyl methacrylate,
ethyl methacrylate and methyl alpha-chloro acrylate. Most
preferred are methyl acrylate, ethyl acrylate, methyl metha-
crylate and ethyl methacrylate.
Anather class of nitrile resins are the graft co-
polymers which have a polymeric backbone on which branchesof another polymeric chain are attached or grafted.
Generally the backbone is preformed in a separate reaction.
Polyacrylonitrile rnay be grafted with chains of styrene,
~82313
- Ll 1 -
vinyl acetate, or methyl methacrylate, for example. The
backbone may consist of one~ two, three, or more com-
ponents, and the grafted branches may be composed oE one~
two, three or more comonomers.
The most promising products are the nitrile co-
polymers that are partially grafted on a preformed
rubbery substrate. This substrate contemplates the use
of a synthetic or natural rubber component such as poly
butadiene, isoprene, neoprene~ nitrile rubbers, natural
rubbers, acrylonitrile-butadiene copolymers, ethylene-
propylene copolymers, and chlorinated rubbers which are
used to strengthen or toughen the polymer. This rubbery
component may be incorporated into the nitrile containing
polymer by any of the methods which are well known to
those skilled in the art, e.g., direct polymerization of
monomers~ grafting the acrylonitrile monomer mixture onto
the rubber backbone or physical admixtures of the rubbery
component. Especially preferred are polymer blends derived
by mixing a graft copolymer of the acrylonitrile and co-
monomer on the rubber backbone with another copolymer of
acrylonitrile and the same comonomer. The acrylonitrile~
based thermoplastics are frequently polymer blends of a
grafted polymer and an ungrafted homopolymer.
G'ommercial examples Or nitrile resins include BARE~
210 resin, an acrylonitrile-based high nitrile resin con-
taining over 65% nitrile, and LOPAC ~ resin containing
-42-
over 70% ni-trile~ three-fourths of it derived rrom metha-
cry].onitrile.
In order to better match the viscosity characteristics ~ -
of the thermoplastic engineering resin, the polyacetal
and the block copolymer, it is sometimes useful to first
: blend the dissimilar thermoplast;c engineering resin with
a viscosity.modi~i.er before blending the resulting mixture
with the pol.yacetal and block copolymer. Suitable viscosity
modifiers have a relatively high viscosity, a melt temper-
10 ature of over 230 C~ and possess a viscosity that is not
very sensitive to chan~es in temperature. Examples o~ suit~
able viscosity modifiers include poly(2,6-dimethyl-1,4-
phenylene)oxide and blends of poly(2,6-dimethyl-1,ll-phenyl-
:~ ene)oxide with po]ystyrene.
The poly(phenylene oxides) inclucled as possible
viscosity modifiers may be presented by the following ~ ~.
formula:
R
~r~t
. R'1 m
wherein R1 is a monovalent substituent selected from the
group consisting Or hydrogen, hydrocarbon radicals rree of
a tertiary alpha-carbon atom, halohydrocarbon radicals
having at least two carbon atoms between the halogen
atom and phenol nucleus and being free of a tertiary
alpha-carbon atom, hydrocarbonoxy radicals free of
aliphaticg tertiary alpha-carbon atoms 9 and halohydro-
carbonoxy radicals having at least two carbon atomsbetween the halogen atom and phenol nucleus and being free
of an aliphatic, tertiary alpha-carbon atom; R'l is the
same as Rl and may additionally be a halogen; m is an
integer equal to at least 50, e.g., from 50 to 800 and
preferably 150 to 300. Included among these preferred
polymers are polymers having a molecular weight in the
; range of between 6,ooo and 100,000, preferably 40,000.
Preferably, the poly(phenylene oxide) is poly(2,6-di-
methyl 1,4-phenylene)oxide.
~5 Cornmercially, the poly(phenylene ~xide) is available
as a blend with styrene resinO These b:Lends typically
comprise between 25 and 50% by weight polystyrene unitsJ
and are available under the _ _
B ~or~ ,~
trade ~ NORYL ~f thermopla,stic resln. The preferred
molecular weight when employing a poly(phenylene oxide)/
polystyrene blend is between 10,000 and 50,000, preferably
around 30,000.
The amount of viscosity modifier employed depends
primarily upon the diff'erence between the viscosities of
the block copolymer and the engineering thermoplastic resin
at the temperature Tp. The amounts may ran~e from O to 100
3~
parts by weight viscosity modifier per 100 parts by weight
engineering thermoplastic resin, prefer-ably from 10 to 50
parts by weight per 100 parts of engineerin~ thermoplastic
resin.
There are at least two methods (other than the absence -
of delamination) by which the presence of an interlocking
network can be shown. In one method, an lnterlocking net-
work is shown when moulded or extruded obJects made from
the blends of this invention are placed in a refluxing
solvent that quantitatively dissolves away the block co-
` polymer and other soluble components~ and the remaining
polymer structure (comprising the thermoplastic engineer-
~; ing resin and polyacetal3 still has the shape and con-
tinuity of the moulded or extruded object and i~ inkact
structurally without any crumbling or delamination, and
,
the refluxing solvent carries no insoluble particulate
matter. If these criteria are fulfilled~ then both the
unextracted and extr~cted phases ~e interlocking and
continuous. The unextracted phase must be continuous
- 20 because it is geometrically and mechanically intact.
The extracted phase must have been continuous before
extraction, since quantitative extraction o~ a dispersed
phase from an insoluble matrix is highly unlikely.
Finally, interlocking networks must be present in order
to have simultaneous continuous phases. ~lso~ confirmation
of the continuity of the unextracted phase may be
~ 5~
conf'irmed by rn:icroscopic e~amination. In the present blends
containing more than two components, the interlocking
nature and continuity of each separate phase may be
established by selective extraction.
In the second method, a mechanical property such as
tensile modulus is measured and compared with that expected
from an assumed system where each continuous isotropically
distributed phase contributes a fraction of the mechanical
response, proportional to its compositional fraction by
volume. Correspondence of the two values indicates presence
of the interlocking networkg whereas, if the interlocking
network is not present, the measured value is different than
that of the predicted value.
.~ An important aspect of the present invention is that
~15 the relative proportions of the various polymers in ~he
blend can be varied over a wide range. The relative
proportions of the polymers are present;ed below in parts
by weight (the total blend comprising 'L00 parts):
Parts by Preferred
weight parts by
;20 weight
Dissimilar engineering
thermoplastic resin 5 to 4~ 10 to 35
Block copolymer 4 to 40 8 to 20
The polyacetal is present in an amount greater than
the amount of the dissimilar engineering thermoplastic,
-116-
i.e., the weight ratio of polyacetal to dissimilar
engineering thermoplastic is greater than 1:1. Accordingly,
the amount of polyacetal may vary from 30 parts by weight ;1
to 91 parts by weight, preferably from 48 to 70 parts by
weight. Note that the minimum amount of block copolymer
necessary to achieve these blends may vary with the
particular engineering thermoplastic.
; The dissimilar engineering thermoplastic resin, poly~
acetal and the block copolymer may be blended in any manner
~lO that produces the interlocking network. ~or example, the
resin, polyacetal and block copolymer may be dissolved in
a solvent common for all and coagulated by admixing in a
solvent in which none of the polymers are soluble. But, a
particularly useful procedure is to intimately mix the
polymers in the form of granules and/or powder in a
high shear mixer. "Intimately mixing" means to mix
the polymers with sufficient mechanical shear and thermaI
energy to ensure that interlocking of the various
.: ~\ ,
~ . .
~8;~3~
-117--
networks is achieved. Intimate mixing is typically
achieved by employing high shear extrusion compounding
machines, such as twin screw compoundlng extruders and
`- thermoplastic extruders having at least a 20:1 L/D ratio
and a compression ratio of 3 or 4:1.
;; The mixing or processing temperature (~p) is selected
in accordance with the particular polymers to be blended.
For example~ when melt blending the polymers instead of
solution blending, it will be necessary to select a
processing temperature above the melting point of the
highest melting point polymer. In addition, as explained
more fully hereinaf`ter, the processing tempera-ture may
also be chosen so as to permit the isoviscous mixing of ~ ;
the polymers. The mixing or processing temperature may be
between 150C and 400C, preferably between 230C and
300C.
Another parameter that is important in melt blending~
to ensure the forrnation of interlocking networks is matching
the viscosities of the block copolymer, polyacetal and the
dissimilar engineering thermoplastic resin (isoviscous
mixing) at the temperature and shear stress of the mixing
process. The better the interdispersion Or the engineering
resin and polyacetal in the block copolymer network, the
better the chance for f`ormation of co continuous inter-
locking networks on subsequent cooling. Therefore~ it hasbeen found that when the block copolymer has a viscosity
? ~~ ~----~~---------- -----
n poise at temperature Tp and shear rate Or 109 s 1,
it is preferred that the engineering thermoplastic resin
and/or the ~)ol,yace~al have such a viscosity at the temper-
ature Tp and a shear rate of 100 s that the ratio Or the
viscosity of the block copolymer divided by the ~iscosity
Or the engineering thermoplastic and/or polyacetal be
between 0.2 and 4.0, preferably between 0.8 and 1.2. ' ,
Accordingly, as used hereing isoviscous mixing means
that the viscosity of the block copolymer divided by the
viscosity o~ the other polymer or polymer blend at the
temperature Tp and a shear rate Or 100 s 1 is between
0.2 and 4Ø It should also be noted that within an
extruder, there is,awide distribution o~ shear rates.
Therefore~ isoviscous mixing can occur even though the
viscosity curves o~ two polymers difrer at some of the
shear rates.
In some cases, the order Or mixing the polymers is
critical. Accordingly, one ma~ choose to mix the block
copolymer with the polyacetal ,or other polymer ~irst, and
then mix the resulting blend with the dissimilar engineer
ing thermoplastic, or one may simply mix all the polymers
at the same time. There are many variants on the order
Or mixing that can be employed, resulting in the multi-
component blends Or the preC;e~t invention. It is also
clear that the order of mixing can be employed in order
to better match the relative viscosities Or the various
polymers~
3l~
ll9
The block copolymer or block copolymer blend may be
selected to essentially match the viscosity of the
engineering thermoplastic resin and/or po1yacetal.
Optionally~ the block copolymer may be mixed with a
rubber compounding oil or supplemental resin as
described hereinafter to change the viscosity charac-
teristics of the block copolymer.
The particular physical properties o~ the block
copolymers are important in forming co-continuous inter-
locking networks. Specif'ically, the most preferred blockcopolymers when unblended do not melt in the ordinary
sense with increasing temperature, since the viscosity
of these polymers is highly non-Newton:ian and tends to
increase without limit as zero shear stress is approached~
Further, the viscosity of these block copolymers is also -~
relatlvely insensitive to temperatureO This rheological
behaviour and inherent thermal stability Or the ~lock co-
polymer ehhances its ability to retain its network
(domain) structure in the melt so that when the various
blends are ~ade,interlocking and continuous networks are
formed.
The viscosity behaviour of the engineering thermoplastic
resins, an(l ~)olyaccta]s on the other hand, is more sensitive
to temperature than that of the block copolymers. Ac-
cordingly, it is often possible to select a processingternperature Tp at which the viscosities of the block
-50-
copoly~er and dissimilar engineering resin and/or poly-
acetal fall within the required range necessary to form
interlocking networks. Optionally, a viscosity modi~ier,
as hereinabove described, may ~irst be blended with the
engineering thermoplastic resin or po~yacetal to achieve the
necessary viscosity matching.
The blend of partially hydrogenated block copolymer,
pdlyacetal and dissimilar engineering thermoplastic resin
may be compounded with an extending oil ordinarily used
in the processing of rubber~and plastics. Especially
pre~erred are the types Or oil that are compatible with
the elastomeric polymer blocks Or the block copolymer.
While oils of higher aromatics content are satisfactory,
those petroleum-based white oils having low volatility and
less than 50% aromatics content as determined by the clay
gel method (tentative ASTM method D 2007) are particularly
prererred. The oils preferably have an initial boiling
point above 260C.
~he amount of oil employed may vary ~rom O to 100 phr
(phr = parts by weight per hundred parts by weight of
block copolymer), pre~erably from 5 to 30 phr.
The blend o~ partially hydrogenated block copolymer,
polya(~tal and dissimllar engineering thermoplastic resin
may be further compounded with a resin. The additional
resin may be a flow promoting resin such as an alpha-
methylstyrene resin and an end-block plasticizing resin~
~ 3
-5~-
Suitable end~block plasticizing resins include coumarone-
indene resins, vinyl toluene-alpha-methylstyrene co-
polymers~ polyindene resins and low molecular weight
polystyrene resins.
The amount of additional resin may vary from O to
100 phr, preferably from 5 to 25 phr.
Further the composition may contain other polymers,
fillers, reinforcements~ anti-oxidants~ stabilizers,
fire retardants, anti-blocking agents and other rubber
and plastic compounding ingredients.
Examples Or fillers that can be employed are mentioned
in the 1971-1972 Modern Plastics Encyclopedia, pages 240-247.
Reinforcements are also useful in the present polymer
blends A reinforcement may be definecl as the material that
is added to a resinous matrix to improve the strength o~
the polymer. Most of these reinforcing materials are in-
organic or organic products Or high molecular weight.
Examples of reinrorcements are glass fibres, asbestos,
boron fibres, carbon and graphite fibres, whiskersg quartz
and silica fibres, ceramic fibres, metal fibres, natural
organic fibres, and synthetic organic fibres. Especially
preferred are reinforced polymer blends containing 2 to
80 per cent by weight Or glass fibres, based on the total
weight Or the resultirlg rcirllorced blend.
The polymer blends of the invention can be employed
as meta] replacemerlts and in those areas where high
perf`ormance is necessary.
3~
Irl the illustrative Examples given be1ow, various polymer
blends were prepared by mixing the polymers in a 3.125 cm
Sterling Extruder having a Kenics Nozzle. The extruder
has a 2ll:1 L,/D ratio and a 3.8:1 compression ratio screw.
The various materials employed in the blends are
listed below:
1) Bloc~ copolymer - a selectively hydrogenated block
copolymer according to the invention having a
structure S-EB-S.
o B 2) Oil TUFFLO 6056 rubber extending oil.
3) Nylon 6 - PLASKON ~ 8207 polyamide.
4) Nylon 6-12 - ZYTEL ~ 158 polyamid~.
5) Polypropylene - an essentially isotactic poly-
propylene having a melt flow index of 5
(230C/2.16 kg).
6) Poly(butylene terephthalate~ PBT") - ~ALOX
310 resin.
7) Polycarbonate - MERLON ~ M-40 polycarbonate.
8~ Poly(ether sulphone) - 200 P.
9) Polyurethane - PELLETHANE ~ CPR.
10) Polyacetal - DELRIN ~ 500.
11) Poly(acrylonitrile~co-styrene) - BAREX ~ 210.
12) Fluoropolymer - TEFZEL ~ 200 poly(vinylidene
fluoride) copolymer.
In all blends containing an oil component, the block co-
polymer and oil were premixed prior to the addition of the
other polymers.
Illustrative x mple I
Various polymer blends were prepare-d according to the
invention. A blend of two block copolymers of a higher
and lower molecular weight was employed in some polymer
blends in order to better match the viscosity with the
polyacetal and/or other dissimilar engineering thermo-
plastic resin. In some blends, an oil was mixed with the
block copolymer in order to better match viscosities.
Comparative blends not containing a block copolymer were
also prepared. However, these blends were not easily
mixed. For example, blend 115 containing just the poly-
acetal and Nylon 6 suffered from die swell, surging, and
melt fracture. In contrast, in each blend containing a
block copolymer, the polymer blend was easily mixed,
and the extrudate was homogeneous in appearance. Further,
in each blend containing a block copolymer, the resulting
polyblend had the desired continuous, interlocking net-
works as established by the criteria hereinabove described.
~he compositions and test results are presented below
~- 20 in Tables 1 and 2. ~he compositions are listed in percent
by weight.
- 51~ -
.. . .. . .. ... . .. .. . .. . . . .. .... ... .
l O r~ ~
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O L~ Lr~
~t
1--
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.,
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r~
L~
O L~ L~
0~
C-- O C-- ~ :
~ ~I L~\
1- O r~
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00 O O O
~1 ~ O L~ Lr\
r~l ~ ~ ~ ~ .
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Lr\
c) a~ ~ a) rl
o
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Q
. a) oa~ ~d ~~ O
O
Z o ~ Q ~ ~) :5 ~ ~1 ~D C)
~1 ~I c) ,n
O
5: Q~ ~ Q~ 1 ~ O ~
a) o ~ o ~~1 a~ ~ ~ ~ o
~1 r~ rl ~ OO ~) O ~ O C)
m m o ~ P~ ~ z ~
_ .. ............. . _._ ___ __
2~
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r.-- Lr~ L~ : :
Lr~ O O ~ ~:
L~ L~
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o~ O O
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L~ Lr~
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L~ . . .
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r.-- Lt~ ~ r~
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a) o ~ o ~1 ~ a) ~ ~ ~ o
C~ O O ~ O ~ O V
---- m ~ P~
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O O O O O O OO
O O O O O O ~~\
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o~ l n
0~1 0 C~
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. . .. . . ..
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O O O O O O OO
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O O O O OO
O O ~l O OO
L~ ~ L~
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~1 . . .. . . .
~1 ..... .. .
O O O O O O O O
O O ~ O OL('\ O O
~:1~1 ¦ L~ Lr~ G~L~\ ~ ~ L~
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a) o ~ ~ cot--C-- O G~G~
Z; ~1 ~1 ~1
m
-57~ 38 ~
~0
tl,
C~
r~ tL~
Lt~ Lt~ t~l t~l CO ~1C~) ~ ''I t~
Lt~ o ~ c~ co S~ ~0
O O O O O ~ ~ ~I tl~ tl)
tn
co oo~oLt~ O ~ ~ ~ F'l tL
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O ~1 0 0 0 ~1 ~I t~
tl) r~
J OLt~~O~1 ~1 ~ ~I J~ L~ .
"'I ' ot~JLt~Cl ) CO ~ ~ t`~ I '
I . . . . . . . . S I O tt:
t\l O O O ~ ~ Lt'~ tl~
C) C~ C~ C~
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J ~0 ~C~lLt~ ~ ~ t~ OC) O ~ '~'~ rn. ~ ~
. . . . . . . ~1 -~ rn tn t~ tn ~n
tl~ p 5~ p 5~
X O ~ r~ rr~l r~l r-! r-/
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l~ Xtn ,~
tn tl) P r-l
M~ r~ ~ r~
t ~ ~ C~~1 ~1 ~t ~ t~,~ ~ S~ tl~ tl) tL) t~ tl~
N ¦C~ ~ ~ ~ ~ ~ ~1 0r-l triS~
t~ tL~ t~ ~
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Otl) ~rlttJ O ttJtl~ tti tl>
CJ~ Ot\~ ~ C~ O
r,~1 l~0 C~ ~0 0Lt~ 1~ 0 ~
o~ I . . . . . . . C~ 0~1 C~l 1~ ~ Lt~ ~O,
c) Lt~ ~ ~Lt~Lt~ ~ Lt~ ~ ~ ~ ~1 ~1 ~1 ~1 ~1 ~1
CU O I r~ t~l C~ ~ t~l ~D 0
'~1~ ~ ~ o o 0
L~ ~t~J ~ ~t~lc~l CU t~l
~ ~ Lt~
~Itl~ O Lt~
~3 ~ O
r~
O r~Lf`\ O OLt~ O O Lt`\ O X
r-l O ~ ~1 ~ ~rl X
m 0~, ~ tn rl
eS2. c~ tnQ. tn r~ Lt.~
~0 ^ ~ O O
tL) ~ ,~ rl
tL) ~ ~ r~ ~ tQ
S: t~i S~ r~ ~ bO X
O tl~ ,~ r~ _ ~rl ~rl ~rl
S~ ~ ~ ~ o rR rn tn
S~ ~ S~ ~ O ~ ~rl r~
tl) t~ rl ~ O tn tl
~ ~ C~ ~ tD tn ~ ~3 tR
r~ r~ l . r~ r-l r-1 ~ ~
o ~ m o o rl ~ ,~, ~ tL~ E3 r-l El ; ~1 ~ C~ tn r, ~i r~ t~ ~rl ~ ~r~
_ ,~ C) tl~ S~ X ~:1 X
r' . tii t O tL) ~rltl) t~i O t i
tL) O N 1~\ t.~ ~- 0 0 1
r~ Z; ~J ~1 0 ~ ~ O C~ O~
m ~ ~ ~ ,~ ~I N r\ ~ Lt~ ~O ~ OC)
-5~-
~ 2~ ~
The results of the above blends indicate the presence
of unobvious properties for the blends. For example, by
examining -the ratio of the relative increase in Izod
impact strength (at 23C) over the relative decrease in
heat distortion temperature for polymer blends as the
percentage of block copolymers is increased from 0% to
15% at a fixed 1:3 ratio of polyacetal to dissimilar
engineering thermoplastic, it can be seen that much
larger than expected values are obtained. One skilled
in the art would typically expect this value to be
positive and less than 1. However, for blends containing
PBT and polycarbonate the ratios are 13 and 28 respectively.
