Note: Descriptions are shown in the official language in which they were submitted.
8CH-2395
The invention relates to improved compositions of a
polyphenylene ether resin and an alkenyl resin that is
modified with a polysiloxane in the form of small rubber-
like particles. Reinforced and flame-retardant compositions
are also provided. q'he polyphenylene ether resins are a
family of engineering thermoplastics that are well known
to -the polymer art. These polymers may be made by a
variety of catalytic and non-catalytic processes from the
correspondingly phenols or reactive derivati~es thereof.
By way of illustration, certain of the polyphenylene
ethers are disclosed in Hay, U.S. Patents 3,306,874 and 3,306,875
both dated in E'ebruary 28, 1967, and in Stamatoff, U.S. patents
3,257,357 and 3,257,358 ~oth dated June 21, 1966. In the Hay
patents the pol~phenylene ethers are prepared by an
oxidative coupling reaction comprising passing an oxygen-
containing gas through a reaction solution of a phenol
and a metal-amine complex catalyst. Other disclosures
relating to processes for preparing polyphenylene ether
resins, including graft copolymers of polyphenylene
ethers with styrene type compounds, are ~ound in Fox, U.S.
patent 3,356,761 dated December 5, 1967, Sumitomo, U.K. 1,291,60g;
Bussink et al, U.S. patent 3,337,499 dated August 22, 1967;
Blanchard et al, U.S. patent 3,219,626 dated November 23, 1965;
Laakso et al, U.S. patent 3,342,892 dated September 19, 1967;
Borman, U.S. patent 3,344,116 dated September 26, 1967; Hori et al,
U.S. patent 3,384,619 dated May 21, 1968, Fauro-te et al, U.S.
patent 3,440,217 dated April 22, 196g, and disclosures relating
to metal based catalysts which do not include amines, are
known from patents such as Wieden et al, U.S. patent 3,442,885
dated May 6, 1969 (copper-amidines); Nakashio et al, U.S. patent
3,573,257 dated March 30, 1971 (metal-alcoholate or - phenolate);
; Kobayashi et al, U.S. patent 3,455,880 dated July 15,
1969 (cobalt chelates); and the like. In the Stamato~
` ~3~i 3~9 8CfI-2395
U.S. patents, the polyphenylene ethers are produced by
reacting the correspondincJ phenolate ion with an initiator,
such as peroxy acid salt, an acid peroxide, a hypohalite,
and the like, in the presence of a complexing agent.
Disclosures relating to non-catalytic processes, such as
oxidation with lead dioxide, silver oxide, etc., are
described in Price et al., U.S. 3,382,212 dated May 7,
1968, Cizek, U.S. 3,383,435 dated May 14, 1968 discloses
polyphenylene ether-styrene resin compositions.
In the prior art, rubber-modified styrene resins
have been admixed with polyphenylene ether resins to form
compositions that have modified properties. The Cizek
patent, U.S. 3,383,435 discloses rubber-modified styrene
resin-polyphenylene ether resin compositions wherein the
rubber component is of the unsaturated type such as
polymers and copolymers of butadiene. The physical
properties of these compositions are such that it appears
that many of the properties of the styrene resins have
been upgraded, while the moldability of the polyphenylene
ethers is improved.
Nakashio et al.,U.S. patent No. 3,658,945 dated
April 25, 1972 discloses that from 0.5 to 15% by wei~ht
of an EPDM rubber modified by grafting with styrene may
be used to upgrade the impact strength of polyphenylene
ether resins. In Cooper et al., U.S. 3,943,191 dated
March 9, 1976 it is disclosed that when the highly
unsaturated rubber used in compositions of the type
disclosed by Cizek is replaced with EPDM rubber that
has a low degree of residual unsaturation, the thermal
oxidative stability and color stability are improved.
It is disclosed in ~aaf, U.S. 3,737,479 dated
June 5, 1973, that molding resins comprised of poly-
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~13~ 8Cl1-2395
phenylene ether resins and polysiloxanes are useful.
These compositions are prepared by mechanical mixing
and, while the compositions are useful for many purposes,
they have low notched Izod impact strength.
It has now been found that a composition of a poly-
phenylene ether resin and an alkenyl aromatic resin
modified with a polysiloxane in the form of small
rubber-like particles is a very u~eful thermoplastic
molding material having good ductility, good surface
appearance, and good impact strength and having excellent
processing characteristics and thermal oxidative stability.
It is, therefore, a primary object of this invention
to provide improved compositions that are based on poly-
phenylene ether resin and modified alkenyl aromatic
resins.
Another object of this invention is to provide
molding compositions and molded articles that are based
on a polyphenylene ether resin and an alkenyl aromatic
resin modified with a polysiloxane in the form of small
2Q rubber-like particles and that have improved thermal
oxidative stability.
Still another object of this invention is to provide
molding compositions and molded articles that are based
on a polyphenylene ether resin and an alkenyl aromatic
resin modified with a polysiloxane in the form of small
rubber-like particles and that have improved impact
strength.
It is also an object of this invention to provide
the above-described, improved molding compositions in
3Q reinforced and/or flame-retardant embodiments.
The above-mentioned advantages and objects and others
will be readily apparent to those skilled in the art by
- 3 -
~S3~9 8Ct[-2395
the following composi-tions.
The compositions of this invention are -thermoplastic
compositions which comprise:
(a) a polyphenylene ether resin; and
(b) an alkenyl aromatic resin that is modified
with a polysiloxane in the form of a small
rubber-like particles.
The preferred polyphenylene ethers are of the ~ormula
Q
_ ~ O ~
n
Q
wherein the oxygen ether atom of one unit is connected to
the benzene nucleus of the next adjoining unit, n is a
positive integer and is at least 50, and each Q is a
monovalent substituent selected from the group consisting
of hydrogen, halogen, hydrocarbon radicals free of a
tertiary alpha-carbon atom, halohydrocarbon radicals
having at least two carbon atoms between the halogen
atom and the phenyl nucleus, hydrocarbonoxy radicals,
and halohydrocarbonoxy radicals having at leas-t two
carbon atoms between the halogen atom and the phenyl
nucleus.
Examples of polyphenylene ethers corresponding to
the above formula can be found in the above~referenced
patents of Hay and Stamatoff. Especially preferred is
poly~2,6-dimethyl-1,4-phenylene~ ether.
The alkenyl aromatic resin should have at least 25%
of its units derived from an alkenyl aromatic monomer of
-- 4
~36~9 8CH-2395
the formula
CRl = CHR2
R5
~ ~ _ R4 II
R
wherein Rl and R are selected from the group consisting of
hydrogen and lower alkyl or alkenyl groups of from 1 to 6
carbon atoms; R3 and R4 are selected from the group consist-
ing of chloro, bromo, hydrogen, and lower alkyl groups of
from 1 to 6 carbon atoms; and R5 and R6 are selected from
the group consisting of hydrogen and lower alkyl and
alkenyl groups of from 1 to 6 carbon atoms or R5 and R6
may be concatenated together with hydrocarbyl groups to
form a naphthyl group.
Specific examples of alkenyl aromatic monomers include
styrene, bromostyrene, chlorostyrene, ~-methylstyrene, vinyl-
xylene, divinylbenzene, vinyl naphthalene, and vinyl-toluene.
The alkenyl aromatic monomer may be copolymerized with
materials such as those having the general formula
,, R8
. R -- C (H)n ~ - - C - - - (CH2) - R9 III
wherein the dotted lines each represent a single or a double
carbon to carbon bond; R7 and R8 taken together represent a
O O
11 9
C - O - C linkage; R is selected from the group consisting
;
.
`` 1~3~ 3 8CH-2395
of hydrogen, vinyl, alkyl of from 1 to 12 carbon atoms,
alkenyl of from 1 to 12 carbon atoms, alkylcarboxylic
of from 1 to 12 carbon atoms, and alkenylcarboxylic of
from 1 to 12 carbon atoms; n is 1 or 2, depending on the
position of the carbon-carbon double bond; and m i5 an
integer of from 0 to about 10. Examples include maleic
anhydride, citraconic anhydride, itaconic anhydride, aconitic
anhydride, and the like.
The alkenyl aromatic resins include, by way of example,
homopolymers such as homopolystyrene and poly(chlorostyrene),
and styrene-containing copolymers, such as styrene-
chlorostyrene copolymers, styrene-bromostyrene copolymers,
the styrene acrylonitrile- ~-alkyl styrene copolymers,
styrene-acrylonitrile copolymers, styrene butadiene
copolymers, styrene-acrylonitrile butadiene copolymers,
poly- ~-methylstyrene, copolymers of ethylvinylbenzene,
divinylbenzene, and styrene maleic anhydride copolymers,
and block copolymers of styrene butadiene and styrene-butadiene
styrene.
The styrene-maleic anhydride copolymers are described
in U.S. patent 2,971,939 issued February 14, 1961 to Baer,
U.S. patent 3,336,267 issued August 15, 1967 to Zimmerman et al,
and U.S. patent 2,759,804 issued November 6, 1956 to Hanson.
The useful polysiloxanes are the high molecular weight
polymers of the formula
sia()bR ( 4a-2b)
wherein _ and b are each an integer of from about 50 to
about 200,000 and a/b is between about 0.95 and about
1.05. More specifically, the useful polysiloxanes include
those of the formula
.~ ``-s - 6 -
~3~3~ 8CEI-2395
R R
R S i -- O - Z S i R
m
R R
R
I
wherein Z represents a group of formula - Si - O ~ -and
the variable _ is an integer of such a value that the poly-
siloxane, after grafting and cross-linking, has rubber-like
properties, preferably an integer of from about 50 to about
200,000. A small number, preferably less than 106, of the
Z groups may be replaced by branching groups of formula
R O
- Si O or Si - O
O ,;
Some of the R groups, which can be the same or different,
must be capable of (l) grafting to an alkenyl aromatic
resin during polymerization and (2) forming crosslinks so
that the final product contains discrete rubbery particles
comprised of the polysiloxane and polysiloxane graft
copolymer, with occlusion of alkenyl aromatic resin, in a
matrix of an alkenyl aromatic resin, such as polystyrene.
Therefore, at least some of the R groups, preferably at
least one percent~ are selected from the group of un-
saturated hydrocarbons having from one to about 10 carbon
atoms such as vinyl, allyl, and cyclohexenyl groups~ For
example, R could be a 2-methyl allyl, 2-butenyl or 3-
butyenyl group. Other R groups can be alkyl or aryl groups
~ 3~ 8CH-2395
having from one to about 10 carbon atoms, being un-
substituted or substituted by one or more cyano, nitro,
or amino groups or halogen atoms. Exemplary R groups
include methyl, phenyl, cyanoethyl, cyanopropyl, amino-
butyl, chlorophenyl, trifluoropropyl, tetrachlorophenyl,
chloropropyl, and the like.
The alkenyl aromatic resin modified with a poly-
siloxane in the form of small rubber-like particles may
be prepared by dissolving the polysiloxane in the alkenyl
aromatic monomer and polymerizing the mixture, preferably
in the presence of a free-radical initiator, until 90-100%
by weight of the alkenyl aromatic monomer has been reacted
to form the alkenyl aromatic resin modified with poly-
siloxane in the form of small rubber-like particles. See,
for example, Saam et al., "Toughening Polystyrene With
Silicone Rubber," SPE Journal, Vol 29, No. 4, April 1973.
Preferred modified alkenyl aromatic resins will include
from about 4 to about 25% by weight of polysiloxane in
the form of small rubber-like particles, based on the
weight of the modified alkenyl aromatic resin~ The
modified alkenyl aromatic monomer will be comprised of
; polysiloxane rubber par-ticles, partially cross-linked
and grafted with the alkenyl aromatic monomer.
Components (a) and (b) are combinable in a fairly
wide range of proportions. Preferably, the compositions
of this invention will comprise from about 10 to about 95
percent by weight of polyphenylene ether resin (a) and
from about 90 to about 5 parts by weight of alkenyl aromatic
resin modified with a polysiloxane in the form of small
rubber-like particles (b), based on the weightof the total
composition.
The compositions of the invention can also include
~ 3~ 8CH-2395
other ingredients, such as flame retardants, extruders,
processing aids, pigments, stabilizers, fillers such as
mineral fillers and glass flakes and fibers, and the
like. In particular, reinforcing fillers, in amounts
sufficient to impart reinforcement, can be used, e.g.,
aluminum, iron or nickel, and the like, and non-metals,
e.g., carbon filaments, silicates, such as acicular
calcium silicate, asbestos, titanium dioxide, potassium
titanate and titanate whiskers, glass flakes and fibers,
and the like. It is to be understood that, unless the
filler adds to the ~trength and stiffness of the composition,
it is only a filler and not a reinforcing filler as contem-
plated herein. In particular, the reinforcing fillers
increases the flexural strength, the flexural modulus, the
tensile strength and the heat distortion temperature.
Although it is only necessary to have at least a
reinforcing amount of the reinforcement present, in
general, the combina-tion of components (a) and (b) will
comprise from about 20 to about 95 percent by weight and
the filler will comprise from about 80 to about 5 percent
by weight, based on the weight of the total composition.
In particular, the preferred reinforcing fillers
are of glass, and it is preferred to use fibrous glass
filaments comprised of lime-aluminum borosilicate glass
that is relatively soda free. This is known as "E" glass.
However, other glasses are useful where electrical pro-
perties are not so important, e.g., the low soda glass
known as "C" glass. The filaments are madebe standard
processes, e.g., by steam or air blowing, by flame blowing,
or by mechanical pulling. The preferred filaments for
plastics reinforcement are made by mechanical pulling.
The ~ilament diameters range from about 0.000112 to
` ~3~3~ 8CH-2395
other ingredients, such as ~lame retardants, extenders,
processing aids, pigments, stabilizers, fillers such as
mineral fillers and glass flakes and fibers, and the like.
In particular, reinforcing fillers, in amounts sufficient
to impart reinforcement, can be used, e.g., aluminum, iron
or nickel, and the like, and non-metals, e.g., carbon
filaments, silicates, such as acicular calcium silicate,
asbestos, titanium dioxide, potassium titanate and titanate
whiskers, glass flakes and Eibers, and the like. It is
to be understood that, unless the filler adds to the
strength and stiffness of the composi-tion, it is only a
filler and not a reinforcing filler as contemplated herein.
In particular, the reinforcing fillers increase the
flexural strength, the flexural modulus, the tensile
strength and the heat distortion temperature.
Although it is only necessary to have at least a
reinforcing amount of the reinforcement present, in
general, the combination of components (a) and (b) will
comprise from about 20 to about 95 percent by weight and
the filler will comprise from about 80 to about 5 percent
by weight, based on the weight of the total composition.
In particular, the preferred reinforcing fillers
are of glass, and it is preferred to use fibrous glass
filaments comprised of lime-aluminum borosilicate glass
that is relatively soda free. This is known as "E"
glass. However, other glasses are useful where electrical
properties are not so important, e.g., the low soda glass
known as "C" glass. The filaments are made by standard
processes, e.g., by steam or air blowing, by Elame
blowing, or by mechanical pulling. The preferred filaments
for plastics reinforcement are made by mechanical pulling.
The filament diameters range from about 0.000112 to 0.00075
-- 10 --
~ 8CEI-2395
inch, but this is not critical to the present invention.
In general, the bes-t properties will be obtained if
the sized Eilamentous glass reinforcement comprises from
about 5 to about 80% by weight based on the combined
weight of glass and polymers and preferably from about
10 to about 50~ by weight. Especially preferably the
glass will comprise from about ]0 to about 40% by weight
based on the combined weight of glass and resin. Generally,
for direct molding use, up to about 60% of glass can be
present without causing flow problems. However, it is
useful also to prepare the compositions containing sub-
stantially greater ~uantities, e.g., up to 70 to 80% by
weight of glass. These concentrates can then be custom
blended w:ith resin compositions that are not glass
reinforced to provide any desired glass content of a
lower value.
The length of the glass filaments and whether or
not they are bundled into fibers and the fibers bundled
in turn to yarns, ropes or rovings, or woven into mats,
and the like, are also not critical to the invention.
However, in preparing the present compositions it is
convenient to use the filamentous glass in the form of
chopped strands of from about 1/8" to about 1" long,
preferably less than 1/4" long. In articles molded
from the compositions, on the other hand, even shorter
lengths will be encountered because, during compounding,
considerable fragmentation will occur. This is desirable,
however, because the best properties are exhibited by
thermoplastic injection molded articles in which the
30 filament lengths lie between about 0.005 and 0.125 inch.
Because it has been found that certain commonly used
flammable sizings on the glass, e.g., dextrinized starch or
~3~ 9 8CH-2395
syn-thetic polymers, contribu-te flammability often in
greater proportion than expected from the amount present,
it is preferred to use lightly sized or unsized glass
forcements in those compositions of the present invenkion
which are flameretardant. Sizings, if present, can
readily be removed by heat cleaning or other techniques
well known to those skilled in -the art.
It is also a feature of this invention to provide
flame-retardant thermoplastic compositions, as defined
above, by modifying the composition to include a flame~
retardant additive in a minor proportion but in an
amount at least sufficient to render the composition non-
burning or self-extinguishing. The flame-retardant
additives useful in this invention comprise a family of
chemical compounds well kno~n to those skilled in the
art. Such flame-retardant additives include a halogenated
organic compound, a halogenated organic compound in
admixture with an antimony compound, elemental phosphorus,
a phosphorus compound, compounds containing phosphorus-
nitrogen bonds, or a mixture of two or more of the fore-
going.
Among the useful halogen-containing compounds are
substituted benzenes exemplified by tetrabromobenzene,
hexachlorobenzene, hexabromobenzene, and biphenyls such
as 2,2'-dichlorobiphenyl, 2,4'-dibromobiphenyl, 2,4'-
dichlorobiphenyl/ hexabromobiphenyl, octabromobiphenyl,
decabromobiphenyl, and halogenated diphenyl ethers
containing from 2 to 10 halogen atoms.
The preferred halogen compounds for this invention
are aromatic halogen compounds such as halogenated diphenyl
ethers having from 2 to 10 halogen atoms per molecule, or a
mixture of at least two of the foregoing. Especially
~3~a~ 8CH-2395
preferred is decabromodiphenylether, alone or mixed with
antimony oxide.
In general, the preferred phosphors compounds are
selected from the group of phosphates, phosphonates, and
phosphine oxides.
The preferred phosphate is triphenyl phosphate. It
is also preferred to use triphenyl phosphate in combination
with hexabromobenzene and, optionally, antimony oxide.
Especially preferred is a composition comprised of mixed
triaryl phosphates with one or more isopropyl groups on some
or all of the aryl rings, such as Kronitex 50 supplied by
Food Machinery Corporation.
Other flame-retardant additives are known to those
skilled in the art. See, for example, Cooper et al.,
U.S. Patent No. 3,943,191 dated March 9, 1976.
In general, however, the amount of additive will be
from about 0.5 to 50 parts by weight per hundred parts of
components (a) and (b). A preferred range will be from
about 1 to 25 parts, and an especially preferred range will
be from about 3 to 15 parts of additive per hundred parts
of (a) and (b). Smaller amounts of compounds highly
concentrated in the elements responsible for flame re-
tardance will be sufficient, e.g., elemental red phosphorus
will be preferred at about 0.5 to 10 parts by weight per
hundred parts of (a) and (b), while phosphorus in the form
of triphenyl phosphate will be used at about 3 to 25 parts
of phosphate per hundred parts of (a) and (b), and so forth.
Halogenated aromatics will be used at about 2 to 20 parts
and synergists, e.g., antimony oxide, will be used at about
1 to 10 parts by weight per hundred parts of components (a)
and ~b).
The compositions of the invention may be formed by
- - 13 -
~3~3~ 8CH~2395
conventional techni~ues, that is, by Eirst dry mixing the
components to form a premix, and then passing the premix
through an extruder at an elevated temperature, e.g., 425
to 640 F.
By way of illustration, glass roving (a bundle of
strands of filaments) is chopped into small pieces, e.g.,
1/8" to 1" in length, and preferably less than 1/4" in
length, and put into an extrusion compounder with (a) the
polyphenylene ether resin, (b) the alkenyl aromatic resin
modified with a polysiloxane in the form of small rubber-
like particles, and (c) the flame-retardant additive(s),
to produce molding pellets. The fibers are shortened and
predispersed in the process, coming out at less -than 1/16
long. In another procedure, glass filaments are ground or
milled to short lengths, are mixed with the polyphenylene
ethere resin, the polysiloxane-modified alkenyl aromatic
polymer, and optionally, flame-retardant additive(s) by
dry blending, and then are either fluxed on a mill and
ground, or are extruded and chopped.
In addition, compounding should be carried out to
insure that the residence time in the machine is short;
that the temperature is carefully controlled, that the
frictional heat is utilized; and that an intimate mixture
between the resins and the additives is obtained.
The following examples are set forth as further
illustration of the invention and are not to be construed
as limiting the invention thereto.
A polystyrene modified with a polysiloxane in the form
of small rubber-like particles, was prepared. The poly-
siloxane used was a high molecular weight gum wherein
13.5 mole percent of the repeat units were methyl vinyl
siloxy units and the remainder were dimethyl siloxy units.
-- l D~ -- .
8CEI-2395
The gum contained a small amount of a trimethylsiloxy group
as a chainstopper.
A solution oE 81.5 g of -the po:Lysiloxane gum in 919 g
of styrene was transferred, under n:itrogen, to a one gallon
stainless steel reaction vessel, and 1.0 g of tert-butyl
peracetate was added. The system was purged with nitroyen,
and the solution was heated, with vigorous stirring, for
three hours at 100C. The polymer was suspended in 1500
ml of water containing 4.0 of poly(vinyl alcohol) and 3~0 g
of gelatin, 8.0 g of di-tert-butyl peroxide was added,
and the mixture was heated for one hour at 100C, for two
hours at 120C, for one hour at 140C, and for two and one
half hours at 155C. The beads of polysiloxane-polystyrene
graft copolymer were filtered off, washed with water, and
dried.
Examination by optical microscopy and by transmission
electron microscopy showed the structure typical of rubber-
toughened polystyrene, with particles of the polysiloxane
on the order of one micron in diameter, with inclusion of
polystyrene, in a matrix of polystyrene. The product
contained 13.5~ of tolueneinsoluble gel, with a swelling
index, in roluene, of 4.6.
Fifty parts of poly(2,6-dimethyl-1,4-phenylene) ether,
50 parts of grafted copolymer prepared according to Example I,
- 1 part of tridecyl phosphite, 3 parts of triphenyl phosphate,
1.5 parts of polyethylene, 0.15 parts of zinc sulfide, and
Q.15 parts of zinc oxide were mixed and extruded at 575F
in a 28-mm twinscrew extruder. The extruder pellets were
molded at 520F into standard test pieces on a 3 oz.
Newbury injection molding machine. The product had Gardner
impact strength of 150 in. lbs. Izod impact strength - 2.5
ft. lbs/in of notch (1/8"~, tensile strength of 8800 p.s.i.,
- 15 -
~ 3~ 8CH-2395
and a heat distortion temperature of 258F.
For comparision a similar composition was prepared by
mechanical blending and coex-trusion of 400 g of poly(2,6-
dimethyl-1,4-phenylene) ether, 368 g of polys-tyrene homo-
polymer (Dylene 8G available from Koppers Co., Inc.), 32 g
of organopolysiloxane, 12 g of polyethylene, 24 g of
triphenyl phosphate, 8 g of tridecy] phosphite, 1.2 g of
zinc sulfide, and 1.2g of zinc oxide. The product had
Izod impact strength of only 0.9 ft.lbs/in., of notch and
Gardner impact strength less than 5 in-lbs.
Sixty parts of poly(2,6-dimethyl-1,4-phenylene) ether,
40 parts of grafted copolymer prepared according to
Example I, 1 part of tridecyl phosphite, 6 parts of triphenyl
phosphate, 0.15 parts of zinc sulfide, and 0.15 parts of
zinc oxide were extruded at 590F and molded at 540F, as
described in Example I. A second, similar composition
was prepared by mechanical mixing of the organosiloxane,
poly(2,6-dimethyl-1,4-phenylene) ether, polystyrene homo-
polymer, and extruded, along with the tridecyl phosphite,
triphenyl phosphate, zinc sulfide, and 2inc oxide.
Properties of the two compositions are compared in
table below:
Property Example III C-l*
Izod Impact Strength 1.5 1.0
(ft lbs~in. of notch2
Gardner Impact Strength 125 5
(in. lbs~
Gloss No. 61 40
Heat Distortion Temperature( F~ 271 264
__________________________
* Control, ingredients mechanically mixed.
Another composition similar to Example III but having
FG-834 (a polybutadiene-modified polystyrene available from
- 16 -
~3~ 3 8CH-2395
Foster Grant) in place of the grafted polysiloxane-poly-
styrene copolymer, was prepared. This composition was
extruded at the same temperature as the composition of
Example III, with the feed rate adjusted to maintain the
same torque. The composition comprised of FG-834 extruded
at a rate of 60 g/min while the composition comprised of
the grafted polysiloxane-polystyrene copolymer extruded
at the rate of 80 g/mm.
It can be seen from the above that thermoplastic
molding compositions prepared according to this invention
have improved impact strength. They also demonstrate
improved surface appearance and improved processability.
Obviously, other modifications and variations of
the present invention are possible in the light of the
above teachings. It is, therefore, to be understood that
changes may be made in the particular embodiments described
above which are within the full intended scope of the
invention as defined in the appended claims.
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