Note: Descriptions are shown in the official language in which they were submitted.
2~3~2
-1- 337-2164 (8CT-4858)
POLY~ST~R, PDLYCAR~ONAT~ AND/OR POLYP BNYL~NE
ETHER WITH POLYORGANOSILOXANE/POLYVINYL-
8ASED GRAET ~eTJ~ACRYLAT~ POLY~BRS
CROSS-R~F~R~C~ TO R~LATED APPLICATIONS
This application is related to the following
commonly owned, concurrently-filed U.S. patent
applications:
ATTY'S SOE~J~CT
S~RIAL NO DSC~T HATT~R APPLICANT(S)
337-2159 Polyorganosiloxane/ I-C. W. Wang
(8GT-483B/ polyvinyl-based
60) Graft Polymers,
Process and Thermo-
plastic Compositions
Containing the Same
337-2160 Thermoplastic J.L. DeRudder
t8CT-4839) Molding Com- F.J. Traver
po.citions Con- I-C. W. Wang
taining Polyorgano-
siloxane/polyvinyl-
based Graft Polymer
Modifier 5
337-21~1 Low Gloss Molded J.L. DeRudder
(8CT-4840) Articles Using H. Savenije
Polyorganosiloxane/ I-C. W. Wang
polyvinyl-based
Graft Polymers
337-2162 Polyphenylene M.A. Alsamarraie
(8CT-4856) ether or Poly- W.R. ~aaf
phenylene ether/ W.J. Peascoe
Polystyrene with I-C. W. Wang
Polyorganosiloxane/
polyvinyl-based
Graft Polymer
Modifiers
2~339~2
-2- 337-2164 (8CT-4358)
ATTY'S S~aJ~CT
SERIAL NO. DOCR~T ~ATTER APPLICANT(S)
337-2163 Polyorganosiloxane/ M.A. Alsmarraie
(8CT-4857) polyvinyl-based S.Y. Hobbs
Graft (meth)- I-C. W. Wang
acrylate Polymers V.H. Watkins
337-2165 Flame Retardant I-C. W. Wang
(8CT-4859) Polyorganosiloxane-
based Graft Polymers
337-2167 Polycarbonate and J.L. DeRudder
(8CT-4861) Polyester Blends I-C. W. Wang
Modified with Poly-
organosiloxane
Graft Polymers
Combined with
Diene Rubber-based
Graft Polymers
337-2168 Polyesters Modified J.L. DeRudder
(8CT-4862~ with Polyorgano- I-Co W. Wang
siloxane/polyvinyl-
based Graft Polymers
FIELD OF T~8 INVgNTION
The invention relates to thermoplastic resins
comprising a poiycarbonate resin, a polyester resin, and
a polyphenylene ether resin or various combina~ions of
the foregoing and a polyorganosiloxane~polyvinyl-based
graft (meth)acrylate polymer modifier which exhibit
enhanced impact strength, weld line strength and flame
re-~iqtance; low agglomeration; good rubber dispersion;
good blend morphology and other desirable properties
without surface mottling and without a tendency to
delaminate.
~ACRGRO~ND OF T~ I~VENTIO~
A novel polyorganosiloxane/polyvinyl-based
graft polymer has been discovered which is extremely
2~3~4~
-3~ 337-2164 (8CT-4858)
useful as a modifier for various thermoplastic resins
while maintaining many unique features of silicone
rubber.
It shows good blend morphology, good rubber
dispersion and no tendency to agglomerate, all as shown
by trans~ission electron microscopy (TEM), while
imparting good impact strength and ductility at a wide
range of temperatures with no tendency to cause
delamination and surface mottling to articles molded
from thermoplastic resin blends containing this
modifier.
There have been many attempts in the art to
provide polyorganosiloxane-based graft polymers which
may be useful as impact strength modifiers for
thermoplastic resins. See for example, U.S. Patent No.
2,891,920 (J.F~ Hyde, et al.~; and O. Graiver, et al.,
Rubber Chem. Tech., 56 (5), 918 (1983).
The major deficiencies which have prevented
the widespread use of polyorganosiloxane impact
modifiers in thermoplastic resins have included raw
material costs, relatively poor rubber integrity, and
the incompatibility of the silicone-based rubber
modifier and the thermoplastic resin. Additionally, the
siloxane polymerization process requires ca.eful control
to eliminate contamination of the silicone rubber by
linear or cyclic siloxane oligomers. Surface delamination
in molded thermoplastic parts has been partially
attributed to the presence of such oligomer contaminants
in the silicone rubber.
Polycarbonate resin compositions and blends of
polycarbonate resins with other thermoplastic resins are
widely used because of their excellent properties.
Polycarbonate resin compositions and mixtures thereof
with a saturated polyester and/or a poly(etherester)
elastomer with a polyorganosiloxane-based impact
2 ~ 3 ~ 2
-4- 337-2164 (8CT-4858)
modifier are described, for example, in European Patent
Application No. 0,249,964. Xt is disclosed therein that
very desirable improvements in chemical resistance,
weather resistance and low temperature impact resistance
are achieved if an additive comprising a silicone-based
graft polymer is usedO
Polyphenylene ether resin compositions alone
or in blends with other resins are also widely used
because of their excellent properties. Polyphenylene
ether resin compositions and mixtures thereof with a
polystyrene resin along with polyorganosiloxane-based
modifiers are described, for example, in European Patent
Application No. 0,260,552. It is disclosed therein that
very de~irable improvements in impact resistance, heat
resistance, mechanical strength, surface appearance, and -
moldability and flow properties are achieved if an
additive comprising a silicone-based graft polymer is
used.
8Oth of the above references used a modifier
comprising a silicone rubber onto which a vinyl
monomer(s) is grafted in the presence of a graft-linking
agent. Mention is also made of European Patent
Application No. 0,246,537 which also describes the use
as an impact modifier of a polyorganosiloxane polymer
substrate on which are subsequently grafted first and
second vinyl-based polymer stages. European Patent
Application No. 0,260,552 also describe~ soaking the
first stage substrate with the second stage monomer(s)
to cause an "entangling" thereof with the silicone prior
to subsequently polymerizing the second stage. Such
modifiers have relatively poor rubber integrity and
incompatibility with the resins. This may lead to poor
surface appearance and delamination in the molded
articles.
2~3~2
-5- 337-2164 (8CT-4858)
Also relevant for its broad teachings is
BASF's U.R. Patent No. 1,590,549 which also describes a
silicone rubber graft polymer for thermoplastics and
particularly Example 6 which discloses a composition
comprising 90 weight percent of polycarbonate and 10
weight percent of the graft polymer discussed immediately
above; poor compatibility is observed with all of these
compositions.
Each of these disadvantages can be overcome by
the practice of the present invention where polyorgano-
siloxane rubber is replaced by a co-homopolymerized
substrate(s) of polyorganosiloxane/polyvinyl-based
polymer(s) which is subsequently graft polymerized with
a (meth)acrylate polymer, a vinyl aroma~ic/(meth)acrylate
copolymer or a vinyl aromatic/vinyl cyanide/(meth)acrylate
terpolymer with or without an intermediary stage
comprising at least one polymer or at least one
cross~linked vinyl polymer or mixture thereof.
These grafted (meth)acrylate polymers exhibit
no agglomeration, and blends comprising compounded
polycarbonate resins (PC), PC/poly(1,4-butylene
terephthalate) (PBT) resins, PC/PB~/polyphenylene ether
(PPE) resins, PBT/PPE resins, PC/PPE resins, or mixtures
of any of the foregoing mixtures containing the graft
polymers of the present invention exhibit enhanced
impact strength at a wide variety of temperatures and
particularly at low temperature; good tensile strength,
surface appearance, and weld lines; good rubber
dispersion; a highly desirable blend morphology with the
modifier appearing as separate spherical particles; no
delamination; and no agglomeration; while maintaining
other properties, such as weathering and thermal
resistance.
203~
-6- 337-2164 (8CT-4858)
BRI~ D~SCRIPTION OF T~ D~A~INGS
FIG. 1 is a ~ransmission electron micrograph
of a blend of PC, PBT and CSiM ((Si/P5)-MMA wto ratio of
70:30) in accordance with the invention showing no
agglomeration and excellent dispersion of the modifier
in the PC phase.
FIG. 2 is a transmission electron micrograph
of a blend of PC, PBT and CSiM ((Si/PS)-S-MMA wt. ratio
of 80:7:13) in accordance with the invention showing no
agglomeration and excellent dispersion of the modifier
in the PC phase.
FIG. 3 is a transmission electron micrograph
of a blend of polyphenylene ether (PPE), PBT, PC and
CSiM ((Si/PS)-MMA wt. ratio of 70:30) in accordance with
the invention showing no agglomeration and excellent
dispersion of the modifier in the PC phase.
SV~ARY OF T B INV~NTIO~
According to the present invention, there are
provided compositions comprising a mixture (A) comprising
~i) a polycarbonate resin and (ii) a polyester resin; or
a mixture (A-l) comprising (ii) a polyester resin and
(iii) a polyphenylene ether resin; or a mixture (A-2)
comprising (i) a polycarbonate resin, (ii) a polyester
resin, and (iii) a polyphenylene ether resin; or a
mixture (A-3) of any of the foregoing mixtures; and
an effective modifying amount of a multi-stage poly-
organosilioxane/polyvinyl-based graft polymer composition
(~) comprising: (a) as a first stage, a polymeric
co-homopolymerized substrate comprised of, in combination,
an organosiloxane polymer; a vinyl polymer; and
optionally units derived from a cross-linking agent or
agents, units which serve as a graft-linking agent or
agents, units derived from a cross-linking agent or
agents and uni~s from the same or different agent or
agents which serve as a graft-linking agent or agents,
~33~42
-7- 337-2164 (8CT-4858)
or a mixture of any of the foregoing; and ~b) at least
one subsequent stage or stages graft polymerized in the
presence of any previous stages and which is comprised
of a (methJacrylate polymer, a vinyl aromatic/(meth)-
S acrylate copolymer or a vinyl aromatic/vinyl cyanide/(meth)acrylate terpolymer.
Also contemplated by the invention are
compositions as above defined wherein said subsequent
stages comprise (b)(i) a second stage comprising at
least one polymer which optionally includes units
derived from a cross-linking agent or agents, units
which serve as a graft-linking agent or agents, units
derived from a cross-linking agent or agents and units
from the same or different agent or agents which serve
as a graft-linking agent or agents, or a mixture of the
foeegoing; and (b)(ii) a third stage comprising a
(meth)acrylate polymer, a vinyl aromatic/(meth)acrylate
copolymer or a vinyl aromatic/vinyl cyanide/(meth)-
acrylate terpolymer.
DgTAIL8D DESCRI~TION OF T~ INV~NTION
The multi-stage graft polymer of the present
invention is made sequentially by a process which begins
with a co-homopolymerization step.
Co-homopolymerization refers to a polymerization
step where two distinct polymerization mechanisms are
effected concurrently, including simultaneously. In
particular, the first stage co-homopolymerization may
encompass a siloxane polymerization (e.g. ring opening
and condensation mechanism) in conjunc~ion with a
concurrent vinyl polymerization. The discrete
mechanism3 are not seen as competing with each other;
rather, two homopolymers are concurrently produced, each
retaining itq own structure.
6~33~
-8- 337-2164 (8CT-4858)
The co homopoly~erization process may provide
two discrete networks rather than a random copolymer.
While not intending to be bound by any theory, it is
possible that the network(s) comprises two or more
distinct interpenetrating polymer phases which provides
the additional strength needed in the polyorganosiloxane.
This is evidenced by the two distinct glass transition
temperatures which can be detected by differential
scanning calorime~ry (DSC). Preferably, the product of
the co-homopolymeri2ation is rubbery instead of a
resin-like powder.
Subsequent to the co-homopolymerization of the
siloxanes and vinyl-based monomers of the first step, at
least one additional graft polymerization ptocess is
utili~ed to achieve the multi-stage polyorganosiloxane/
polyvinyl-based graft (meth)acrylate polymers of the
invention.
The subsequent graft polymerization is of at
least one (meth)acrylate polymer, vinyl aromatic/~meth)-
acrylate copolymer or vinyl aromatic/vinyl cyanide/(meth)-
acrylate terpolymer.
(Meth)acrylates are generally produced in a
two-step process wherein acetone is reacted with
hydrogen cyanide to form acetone cyanohydrin. This is
then heated with an alcohol in th~ presence of sulfuric
acid to produce the corresponding (meth)acrylate
monomer. The acrylic monomers can be graft polymerized
by free radical process with the aid of an initiator(s).
(Meth)acrylate monomers can also be copolymerized with
other acrylates like methyl or ethyl acrylates and the
like. The vinyl aromatic monomer of the vinyl aromatic/
(meth)acrylate copolymer or of the vinyl aromatic/vinyl
cyanide/(meth)acrylate terpolymer can be a styrenic
monomer such as styrene; alkyl sub~tituted ring styrenes
such as vinyl toluene, divinylbenzene, ethyl styrene or
2~33~J ~2
-9- 337-2164 (8CT-485~)
butyl styrene; chlorine ring substituted styrenes such
as monochlorostyrene or dichlorostyrene; or the like.
The vinyl cyanide monomer can be produced by the
condensation of ethylene oxide with hydrogen cyanide to
form beta-hydroxy nitrile which is subsequently
dehydrated to acrylonitrile, by the vapor-phase
ammoxidation of propylene over a suitable catalyst or
other methods known to the art. Examples of such vinyl
cyanides include, but are not limited to, acrylonitrile
or methacrylonitrile. Particularly, preferred
subsequent stages graft polymerized in the pre~ence o
the first stage comprise methyl methacrylate polymer or
styrene/methyl methacrylate copolymer.
The foregoing polyorganosiloxane/polyvinyl-based
graft (meth)acrylate polymer can be isolated and
utilized, for example, as an impact strength modifying
agent for thermoplastic resins as will be discussed in
detail below.
Additional cross-linking and/or graft-linking
agent(s) can be utilized in this initial stage to
provide co-homopolymerized networks from both polymeric
constituents which provide greater rubber integrity.
The first stage rubbery substrate is provided
by a series of sequential processing steps. In a
premixing step, the ingredients required for the
co-homopolymerization of the organosiloxane(s) and
vinyl-based monomer(s) are premixed with water and
suitable cross-linker(s), graft-linker(s), initiator(s)
and surfactant(s). The premixed inqredients are
homogenized by conventional means. The co-homo-
polymerization reactions may begin at this early stage
of the process, but these reactions are generally slow
at room temperature. The homogenized reactants may be
directed to a reactor vessel, typically stainless steel
or glass flasks under a nitrogen blanket. Heat is
2~33~2
-10- 337-2164 (8CT-4858)
applied to facilitate the reaction. For typical 5 to 50
gallon stainless steel reactors, a 3 to 6 hour residence
time at 75C to 90C is adequate to complete the
co-homopolymerizations. Cooling for 2 to 6 hours will
reduce the temperature to at least room temperature
where the reaction mass can be held, typically for 3 to
72 hours. Cooling to lower temperatures (e.g. 5C) may
be sometimes preferred since this may enhance the
properties of the formed polyorganosiloxane/polyvinyl
substrate.
Cooling to room temperature or lower allows
the polyorganosiloxane portion to build molecular weight,
thereby minimizing the extractable silicone rubber
fragments and optimizing physical properties of the
product for certain applications. Generally, lower
temperatures are preferred when it is desired to
optimize the elasticity of the formed polyorganosiloxane/
polyvinyl substrate.
The initiator for the siloxane component of
the co-homopolymerization can be any ionic ring opening
type initiator when cyclic siloxanes are utilized, such
as alkylarylsulfonic acids, alkyldiaryldisulfonic acids,
alkylsulfonic acids, or the like. The best suited
example is dodecylbenzenesulfonic acid which can act as
an initiator and at the same time as an emulsifier. In
some cases, the joint use of a metal salt of an afore-
mentioned sulfonic acid is also preferred.
The initiator for the styrenic or other vinyl
monomers in the co-homopolymeriza~ion process can be any
3C organic soluble radical initiator, such as azobisiso-
butyronitrile (AIBN) and the organic peroxides, e.g.
benzoyl peroxide, dichloro benzoyl peroxide, tert-butyl
perbenzoate. Also suitable are water soluble radical
initiators such as the persulfates. Although it is
possible to charge this type of initiator at the
2~3~2
-11- 337-2164 (8CT-4858)
beginning of the process, it is preferred that it be
charged continuously or incrementally during the
co-homopolymerization period. Since persulfate is less
stable in the acid conditions of the siloxane
polymerization, it is preferred that the persulfate be
added over time to keep the vinyl polymerization
running. Particle size, pH and total solids measurements
can be readily monitored at this stage of the process.
A latex rubber emulsion prepared as described above will
generally contain particles having an average diameter
of 100 to 800 nanometers and preferably 150 to 400
nanometers. The particle size is particularly
influenced by the homogenization pressure (and the
number of pas~es through the homogenizer) and the
lS composition of the reaction ingredients. A pressure
- range of 2000 to 12000 psi is typical and 3000 to 9000
psi is preferred. Multiple passes through the
homogenizer may be preferred, but on a large scale a
single pass may be most practical.
The foregoing reaction steps must be followed
by a suitable neutralization process to provide the
products of the invention. The main object of the
neutralization is to quench the siloxane polymerization.
This is accomplished by adding a caustic solution such
as sodium hydroxide, potassium hydroxide, potassium or
sodium carbonate, sodium hydrogen carbonate,
triethanolamine or triethylamine. The pH of the
reaction solution may be raised from a level of 1 to 3
to a pH of at least about 6.5, and typically 7 to 9.
It is often desirable to add additional soap
or surfactant to the emulsion formed at the end of the
first stage, prior to ~he neutralization step.
Additional surfactant tends to facilitate avoidance of
premature agglomeration or flocculation of the
co-homopolymerized rubber in the quench step~
'~3~
-12- 337-2164 (BCT-4858)
The foregoing co-homopolymerization process
provides a rubbery network composed of a polyorgano-
siloxane/polyvinyl substrate. This substrate is the
first stage of the graft polymer of the present
invention. The next stage involves the graft
polymerization of (meth)acrylate-functional (or vinyl
aromatic/(meth)acrylate-functional or vinyl aromatic/vinyl
cyanide/(meth)acrylate-functional) moieties onto the
graft sites provided by the rubbery ~ubstrate particles
in the latex formed in the first stage. Intermediary
stages are optional but may be preferred for certain
applications. The intermediary stages may comprise at
least one polymer and optionally units derived from a
cross-linking agent or agents, units which serve as a
graft-linking agent or agents, units derived from a
cross-linking agent or agents and unitR from the same or
different agent or agents which serve as a graft-linking
agent or agents, or a mixture of any of the foregoing.
The grafted polymers will preferably be the
product of a (meth)acrylate polymerization process. The
(meth)acrylate polymerization is accomplished in an
emulsion; therefore water soluble initiators are
preferred; e.g., potassium persulfate, sodium persulfate
and ammonium persulfate. It is practical to add the
initiator at the beginning of this step, prior to
charging the (meth)acrylate monomers, the vinyl aromatic/
(meth)acrylate comonomers or the vinyl aromatic/vinyl
cyanide/(meth)acrylate termonomers for the second stage
polymerization. Other Redox initiator systems, such as
cumene hydroperoxide/ferrous sulfate/glucose/sodium
pyrophosphate, can also be utilized at this stage as
well as other organic peroxides.
Suitable monomers for intermediate graft
polymerization for second stage (b)(i) include without
limitation: alkenyl aromatic compounds such as styrene,
2~33a~42
-13- 337-2164 (8CT-4858)
divinylbenzene, alpha-methylstyrene, vinyl toluene,
halogenated styrene and the like; methacrylates such as
methyl methacrylate and 2-ethylhexyl methacrylate;
acrylates such as acrylic acid, methyl acrylate, ethyl
acrylate and butyl acrylate; vinyl cyanide compounds
such as acrylonitrile and methacrylonitrile: olefins
such as ethylene, propylene, butadiene, isoprene, and
chloroprene; and other vinyl compounds such as
acrylamides, N-~mono or disubstituted alkyl)acrylamides,
vinyl acetate, vinyl chloride, vinyl alkyl ethers, allyl
(meth)acrylate, triallyl isocyanurate, ethylene
dimethacrylate, diallyl maleate, maleic anhydride;
maleimide compounds such as maleimide or N-phenyl (or
alkyl) maleimide; and mixtures of these monomers.
Sequential multi-stage polymerization
processes of this type are sometimes referred to as
core-shell processes. It i9 preferred, however, to
describe them a~ multi-stage graft polymerization
processes wherein the initial stage provides a
co-homopolymerized organosiloxane/vinyl-based substrate.
This substrate may have sufficient grafting sites for a
second or subsequent stage to be grafted thereto.
Grafted (meth)acrylate polymer, vinyl aromatic/(meth)-
acrylate copolymer or vinyl aromatic/vinyl cyanide/(meth~-
acrylate terpolymer as the outermost stage i5 preferred,yet many other intermediary stages such as a polystyrene
or a poly~butyl acrylate) stage are also contemplated.
In general, the first stage substrate
comprising the co-homopolymerized polyorganosiloxane/
polyvinyl-based substrate will comprise approximately 5
to 95 weight percent of the total graft polymer based
upon the weight of the first stage and the subsequent
stage or stages taken together. Preferably, the first
stage will comprise approximately 30 to 90 weight
percent on the same basis. Correspondingly, the
2~3~
-14- 337-2164 (8CT-4858)
subsequent stages, comprising the additional grafted
(meth)acrylate polymer, vinyl aromatic/(meth~acrylate
copolymer or vinyl aromatic/vinyl cyanide/(meth)acrylate
terpolymer will comprise approximately 95 to 5 weight
percent and preferably approximately 70 to 10 weight
percent on the same basis. In the multi-stage systems,
preferably, the ratio of first stage substrate polymer
(a) to second stage polymer (b)(i) is 10:90 to 90:10 and
the amount of third stage polymer (b)(ii) comprises from
about 10 to about 90 parts by weight per 100 parts by
weight of (a), (b)(i), and (b)(ii) combined.
The organosiloxanes useful in the first stage
co-homopolymerization are any of those known to produce
silicone elastomers and may include those which are
hydroxy-, vinyl-, hydride- or mercapto-end capped linear
organosiloxane oligomers.
The polyorganosiloxanes illustratively will be
comprised primarily of units of the formula
nsi~4-n)/2
wherein R is hydrogen or a monovalent hydrocarbon
radical of about 1 to 16 carbon atoms and n is 0, 1 or
2.
Preferred among the organosiloxanes are those
in cyclic form having three or more siloxane units, and
most preferred are those having three to six units.
Such organosiloxanes include without limitation, for
example, hexamethylcyclotrisiloxane, octamethylcyclo-
tetrasiloxane, decamethylcyclopentasiloxane, dodeca-
methylcyclohexasiloxane, trimethyltriphenylcyclotri-
siloxane, tetramethyltetraphenylcyclotetrasiloxane,tetramethyltetravinylcyclotetrasiloxane and octaphenyl-
cyclotetrasiloxane. These or similar organosiloxanes
may be used alone or in combination.
2~33~
-15- 337-2164 (8CT-4858)
The vinyl monomers useful in conjunction with
the co-homopolymerization of organosiloxanes in the
first stage are preferred to be alkenyl aromatic
compounds such as styrene, divinylbenzene, alpha-methyl-
styrene, vinyl toluene, vinyl naphthalene, vinylanthracene, and halogenated styrene or its derivatives.
Other suitable vinyl monomer~ include acrylic acids and
acrylates such as methyl-, ethyl-, allyl-, or
butyl acrylate; metbacrylates such as methyl methacrylate
or 2-ethylhexyl methacrylate; vinyl cyanides such as
acrylonitrile or methacrylonitrile olefins such as
ethylene, propylene, butadiene, isoprene, chloroprene,
vinylimidazole, 5-vinyl-2-norbornene, vinyl pyridine,
vinyl pyrrolidine, vinyl acetate, vinyl alkyl ethers,
vinyl chloride, vinyl furan, N-vinyl carbazole,
allyl (meth)acrylate, triallyl isocyanurate, ethylene
di(meth)acrylate, butylene di(meth)acrylate, diallyl
maleate, maleic anhydride; maleimide compounds such as
maleimide or N-phenyl (or alkyl)maleimides; acrylamides;
N-(mono or di-substituted) acrylamides; and mixtures of
any of these monomers. In general, any rubbery or glassy
vinyl type monomer may be used which can be mixable with
the organosiloxanes. Typically, the vinyl component of
the first stage co-homopolymer will be present in an
amount of approximately 3 to 97 weight percent, and
correspondingly, the polyorganosiloxane component will
be present in an amount of approximately 97 to 3 weight
percent. Preferably, the vinyl-based component will
comprise approximately 5 to 45 weight percent of the
first stage of the co-homopolymerized substrate.
Platinum compounds are often utilized in
conjunction with polyorganosiloxane compositions in
order to enhance the flame retardance o~ the latter.
Platinum complexes are also used as catalysts in certain
hydrosilation processes although such catalysts are not
2~33~2
-16- 337-2164 (8CT-4858)
necessary for the practice of the present invention. As
flame retarding additives, however, there may optionally
be utilized the reaction product of chloroplatinic acid
and organosilicon compounds as described in U.S. Patent
No. 3,220,972. Another platinum compound is seen in
U.S. Patent No. 3,775,452 describing platinum-containing
organopolysiloxanes.
The cross-linker composition used in
conjunction with the organosiloxane component of the
present compositions can have the general formula
R2n-Si(ORl)4 n
wherein n is 0, 1, or 2, preferably 0 or 1, and each
independently represents hydrogen or a monovalent
hydrocarbon radical selected from among alkyl or aryl
radicals having 1 to 16 carbon atoms, preferably methyl,
ethyl and phenyl. R2 can be the same as Rl or can be a
vinyl, alkenyl, thio, or (meth)acryloxyalkyl functional
radical. When R2 is a vinyl, alkenyl, thio, or
acryloxyalkyl radical and n is 1, the cross-linker
compound can also act as a graft-linker.
A preferred cross-linker compound is
tetraethoxysilane. A combination cross-linking and
graft-linking compound is vinyltriethoxysilane. Another
suitable choice is gamma-methacryloxypropyltrimethoxy-
silane.
The multi-stage polyorganosiloxane/polyvinyl-
based (meth)acrylate graft product of the present
invention can be isolated by conventional means such as
hot solution coagulation. For example, an electrolytic
solution of about 0.5 to 5 percent aluminum sulfate or
magnesium sulfate in water can be prepared and heated to
abou~ 75 to 95C. When the latex is added with
agitation, the graft product will precipitate and can be
'~3~2
-17- 337-2164 (8CT-4858)
.
held at elevated temperature for about 10 minutes
whereupon it may be filter washed. Commercial latex
isolation techniques such as spray dryers may also be
utilized.
In a preferred feature of the invention, the
isolated multi-stage graft copolymer may be utilized as
a modifier for thermoplastic resins, particularly a
mixture (A) of (i) a polycarbonate resin and (ii) a
polyester resin; a mixture tA-l) of (ii) a polyester
resin and (iii) a polyphenylene ether resin: a mixture
of (A-2) of (i) a polycarbonate resin, (ii) a polyester
resin, and (iii) a polyphenylene ether resin; or a
mixture (A-3) of any of the foregoing.
The polycarbonate resin (i) in the invention
is produced by using a dihydroxydiarylalkane as the main
starting material and optionally has branched chains.
Such polycaebonate resins are manufactured by known
processes and generally by the reaction of a dihydroxy
compound and/or a polyhydroxy compound with either
phosgene or a diester of carbonic acid. Suitable-
dihydroxydiarylalkanes include those having at least one
alkyl group, chlorine atom, or bromine atom in any of
the positions ortho to the hydroxyl groups. Preferred
exa~ples of the dihydroxydiarylalkane include 4,4'-di-
hydroxy-2,2-diphenylpropane-(bisphenol-A~; tetramethyl-
(bisphenol-A); and bis-(4-hydroxyphenyl)-p-diisopropyl-
benzene. The branched polycarbonate rQsin can be
produced, for instance, by the above-mentioned reaction
but using, for example, 0.2 to 2 mole percent of a
polyhydroxy compound in place of a part of the dihydroxy
compound. Examples of the polyhydroxy compound include
1,4-bis-(4',4,2-dihydroxytriphenylmethyl)-benzene;
phloroglucinol; 4,6-dimethyl-2,4,6-tris-(4-hydroxyphenyl)-
heptene-2; 4,6-dimethyl-2,4,6-tris-(4-hydroxyphenyl)-
heptane,l,3,5-tris-(4-hydroxyphenyl)-benzene: 1,1,1-
~33~
-18- 337-2164 (8CT-4858)
tris-(4-hydroxyphenyl)ethane and 2,2-bis-(4,4-(4,4'-
dihydroxyphenyl)-cyclohexyl)-propane. Particularly
preferred polycarbonate resins are of the bisphenol-A
type.
The thermoplastic polyester resin (ii) in the
present invention is constituted mainly of an aromatic
dicarboxylic acid of 8 to 22 carbon atoms and an
alkylene glycol, cycloalkylene glycol, or aralkylene
glycol of 2 to 22 cabon atoms, but may contain an
aliphatic dicarboxylic acid, e.g. adipic acid or sebacic
acid, and/or a polyalkylene glycol such as polyethylene
glycol, polytetramethylene glycol, or the like in an
amount of up to 5 percent by weight based on the
thermoplastic polyester resin itself. Poly(1,4-butylene
terephthalate) resin can be produced by the
tranaesterification of dimethyl terephthalate with
butanediol through a catalyzed melt polycondensation or
by other methods known in the art. Particularly
preferred polyesters are poly(ethylene terephthalate)
and poly(l,4-butylene terephthalate) or mixtures
thereof.
The polyphenylene ether resin ~ in the
invention is a homopolymer or copolymer represented by
the formula
Q~ Q2
~0 ~
Q Q m
wherein Ql through Q4 are selected independently of each
other from the group consisting of hydrogen and
hydrocarbon radicals and m denotes a number of 30 or
more~
2 ~3 `~ 3 ~
-19- 337-2164 (8CT-4858)
Examples of such polyphenylene ether resins
include poly(2,6-dimethyl-1,4~phenylene)ether, poly(2,6-
diethyl-1,4-phenylene)ether, poly(2,6~dipropyl-1,4-
phenylene)ether, poly(2-methyl-6-ethyl-1,4-phenylene)-
ether, poly(2-methyl-6-propyl-1,4-phenylene)ether,
poly(2-ethyl-6-propyl-1,4-phenylene)ether, copolymer of
(2,6-dimethyl-1,4-phenylene)ether with (2,3,6-trimethyl-
1,4-phenylene)ether, copolymer of (2,6-diethyl-1,4-
phenylene)ether with (2,3,6-trimethyl-1,4-phenylene)ether,
and copolymer of (2,6-dimethyl-1,4-phenylene)ether with
(2,3,6-triethyl-1,4-phenylene)ether. Of these polymers,
preferred are poly(2,6-dimethyl-1,4-phenylene)ether and
a copolymer of (2,6-dimethyl-1,4-phenylene)ether with
(2,3,6-trimethyl-1,4-phenylene)ether. Particularly
preferred is a poly(2,6-dimethyl-1,4-phenylene ether)
resin. There is no particular restriction on the
polymerization degree of the polyphenylene ether resin
used in the invention, but it is preferable to use the
resin havi~g a reduced viscosity of 0.3 to 0.7 dl/g
measured in chloroform at 25C. Resins having a less
reduced viscosity than 0.3 dl~g tend to exhibit low heat
stability while resins having a reduced viscosity
exceeding 0.7 dl/g tend to have inferior moldability.
The amounts of components (A), (A-l), (A-2),
or (A-3) and ~B~ can vary broadly, but will usually be
in the range of from about 1 to about 99 parts by weight
of (A), (A-l), (A-2), or (A-3) to from about 99 to about
1 part by weight of (B), per 100 parts by weight of (A),
(A-l), (A-2), or (A-3) and (B~ together. Preferably
(A), (A-l), (A-2), or (A-3) comprises from about 99 to
about 37 parts by weight and (B) comprises from about 1
to about 63 parts by weight.
The compositions can also be further rendered
more flame retardant with effective amounts, e.g.,
between about 1 and 30 parts by weight per 100 parts by
2 ~
-20- 337-2164 (8CT-4858)
weight of resin, of a flame retardant agent as component
(C), e.g., elementary red phosphorous, phosphorous
compounds, halogen compounds, nitrogen compounds,
antimony oxide, zinc oxide, metal salt(s) of sulfonated
diphenylsulfone, metal salt(s~ of trichlorobenzene-
sulfonic acid, mixtures thereof and the like.
Additionally, reinforcing fillers as component
(D); dyes and colored pigments; heat stabilizers;
thermosxidative stabilizers and W stabilizers; waxes,
lubricants and processing assistants which ensure
trouble-free extrusion and injection molding; and
antistatic agents may be added to the molding compositions
according to the invention.
The reinforcing filler (D) can be comprised of
any oryanic or inorganic fillers including, but not
limited to glass fiber, carbon fiber, aramid fiber,
metallic fiber, asbestos, glass beads, glass flakes,
calcium carbonate, talc, mica, aluminum oxide, boron
nitride, calcium silicate, clay or metal powders or
whiskers.
Conventional proce~se for mixing thermoplastic
polymers can be used for the manufacture of molding
compositions within the invention. For example, the
compositions can be manufactured by using any suitable
mixing equipment, cokneaders or extruders. The mixing
temperature~ are in general from 150 to 370C,
preferably from 200 to 345C. The polymers are fused
and thoroughly mixed, with or without the other
additives described.
The addition of the graft polymers described
above does not adversely influence the processing
stability of the thermoplastically processable plastics
material.
2~33~2
-21- 337-2164 (8CT-4858)
D~SCRIPTION OF T~ PR~F~RRED ~MBODI~NTS
The following examples illustrate the
invention without limitationO All parts given are by
weight unless otherwise indicated. Impact strengths are
reported as notched Izod (NI~ according to ASTM D-256 at
23C unless otherwise specified~ Weld line i5 measured
on one-eighth inch unnotched Izod bars molded in a
double-gated mold. Tensile properties are measured by
ASTM D-638 as Tensile Yield Strength, Tensile Break
Strength, and Elongation Break Strength. Surface gloss,
60, is measured by ASTM D-523, and yellowing is
measured by yellowness index (YI1.
A single slash is used between monomers of a
single stage and a double slash or a hyphen is used as a
shorthand method of indicating separation between
stages. The first stage to be polymerized is written
before the double slash or hyphen, and subsequent stages
are written subsequently.
PRCCBD~RR A
79.1 parts of octamethylcyclotetrasiloxane
(D4), 9.8 parts of tetraethoxysilane (TEOS), 2.3 parts
of gamma-methacryloxypropyltrimethoxysilane (APTMOS),
and 8.8 parts of 2,4,6,8-tetramethyltetravinylcyclotetra-
siloxane (VMD4) are mixed to form Solution 1. 4.9 parts
of styrene (S) and 0.1 part of divinylbenzene (DV~) are
mixed to form Solution 2. l.00 part of dodecylbenzene-
sulfonic acid (DBSA) is dissolved in 300 part of
deionized water (DI H2O) to form Solu~ion 3. 0.025 part
of pota~sium persulfate (R2S2O8) is dissolved in 1.25
parts of deionized water to form Solution 4. Solutions
1 and 2 are admixed and stirred for 30 minutes. The
resultant mixture is added to Solution 3, stirred well,
and homogenized in two stages at 6500 psi. The latex is
transferred to a reactor equipped with an overhead
stirrer, a condenser, an argon sparge tube, an
2~33~
-22- 337-2164 ~8CT-4858)
addition funnel, and a thermometer with a temperature
controller. A continuous stream of argon gas is bubbled
through the latex for 30 minutes with constant stirring.
The temperature is raised to 75C under an argon blanket
and left stirring at 75C for 15 minutes. Solution 4 is
added dropwise to the latex over a one hour period, and
particle size and solid content measurements are
monitored every hour throughout the course of
polymerization. The heat i5 removed after six hours,
but stirring is continued under an argon blanket
overnight. The latex is titrated to p~ 8.5 with an
aqueous potassium carbonate solution (K2CO3). The final
co-homopolymerized substrate latex has a volume averaged
particle size of 228 nanometers in diameter and a solids
content of 19.1 percent. Degree of swelling, measured
using toluene as a solvent, is 6.8.
EXA~PL~ 1
366.5 parts (70 parts of dry rubber) of latex
prepared by the method of Procedure A is placed in a
reaction vessel si~ilar to that used in Procedure A.
The latex is purged with argon gas and heated to 75C
while being stirred constantly. 0.15 part of potassium
persulfate initiator is added. Fifteen minutes later,
30 parts of methyl methacrylate (MMA) are added dropwise
over a period of less than one hour. Tha heat is
applied for a total time of six hours. The latex is
left under argon overnight and yields the CSiM modifier
((Si/PS)-MMA wt. ratio of 70:30). The volume averaged
~ean particle diameter is 227 nanometerR, and graft
efficiency i~ 94 percent using acetone as the extractant.
EXA~PLe 2
The procedure of Example 1 is followed
substituting 419 parts (80 parts of dry rubber) of
2~3~?d
-23- 337-2164 (8CT-4858)
latex prepared by the method of Procedure A, and 0.005
parts of potassium persulfate for the corresponding
components, and 7 parts of styrene, and 0.14 part of
divinylbenezene. The styrene addition period is less
than one hour and is then followed immediately by
disperse addition of 13 parts of methyl methacrylate,
yielding the CSiM modifier ((Si/PS)-S-MMA wt. ratio of
80:7:13). The volume averaged mean particle diameter is
215 nanometers, and graft efficiency is 96 percent.
~AMPLB 3
A well mixed dry blend of 40 parts of
polyester (PBT, poly(l,4-butylene terephthalate), Valox-
315-General Electric Company), 50 parts of polycarbonate
(PC, poly(bisphenol-A carbonate), Lexan- 140-General
Electric Company), 10 parts of CSiM modifier ((Si/PS) MMA
wt. ra~io of 70:30) prepared by the method of Example 1,
and 0.9 part of a stabilizer package is extruded on a
Welding Engineering twin screw extruder operating at 400
rpm and with barrel zones set at 250, 375, 510, 510, 510
and 510F. Tensile and notched Izod bars are molded on
a Boy Injection Molder at 260C. Morphology is
illustrated in FIG. 1. There is good rubber dispersion,
good blend morphology with the CSiM modifier (1)
appearing as separate spherical particles and no
agglomeration in the PC (7) phase of the PC (7)/P8T (91
blend. The (Si/PS) stage (5) and the MMA stage (3) are
also illustrated. No delamination or surface mottling
is seen. Properties are summarized in Table 1.
COMPARATIVE ~AMPL8 3A~
The procedure of Example 3 is followed except
omitting the CSiM modifier. Properties are su~marized
in Table 1.
'~33~2
-24- 337-2164 (aCT-4858)
E~A~æL~ ~
A composition as prepared in Example 3 is
thermally aged by storing at 30C for 96 hours. The
good rubber dispersion and good blend morphology of the
CSiM modifier are still unaffected after thermal aging.
Properties are summarized in Table 1.
~A~PL~ S
The procedure of Example 3 is followed
substituting CSiM ((Si/PS)-S-MMA wt. ratio of 80:7:13)
prepared by the method of Example 2, for the CSiM.
Morphology is illustrated in FIG. 2. There is good
rubber dispersion, good blend morphology with the CSiM
modifier (1) appearing as separate spherical particles
and no agglomeration in the PC (3) phase of the PC
(3)/PBT (5) blend. No delamination or surface mottling
are seen. Properties are summarized in Table 1.
~XA~P~ 6
A composition as prepared in Example 5 is
thermally aged by storinq at 90C for 96 hours. The
good rubber dispersion and good blend morphology of the
CSiM are still unaffected after thermal aging.
Properties are summarized in Table 1.
Examples 3-6 when compared with Comparative
Example 3A* demonstrate improved ductility, high notched
Izod values at a wide range of temperatures, good
tensile strength, and exhibit no surface mottling or
delamination in articles prepared from blends containing
the CSiM modifiers of the present invention.
Particularly, Examples 3 and 5 surprisingly show
improved and excellent rubber dispersion, excellent
blend morphology with the modifier appearing as separate
spherical particles and no agglomeration in the blends.
~`3~
-25- 337-2164 (8CT-4858)
TA~LB 1
Co~positions Co~prisin
PolYe~ter, PolYcarbonate and CSi~
EXAMPLE - 3A~ 4 5 6
Polye~ter A 3 40 40 40 40 40
Polycarbonate 50 50 50 50 50
Stabi~izer Package0.9 0.90.9 0.9 0.9
CSiM 10 - 10 - -
CSiM D 10 10
Tensile Yield Strength
(psi) 7526 - 8S65 7327 8109
Elongation Break
Strength (~) 124 - 121 167 147
Tensile Break
Strength (psi) 7072 - 7531 7611 7653
Notched Izod ( ft-lbs/in)
25C 15.7 114.0 15.5 14.8
0C 12.8 - - 14.9
-15C 11.8 - - 13.7
-30C 8.1 - - 12.3
-45 C
-50C 5.6 - - 7.6
-55 C
Morphology by TEM-
dispersion exc. - - exc.
(FIGURE) (1) (-) (_) (2) (_)
A - poly(l,4-butylene terephthalate) - Valox- 315 - General
Electric Co~pany
B - poly(bisphenol-A carbonate) - Lexan- 140 - General Slectric
Co~pany
C - (Si/PS)-MMA wt. ratio of 70:30, Example 1
D - (Si/PS)-S-MMA wt. ratio of 80:7:13, Example 2
'~ ~ 3 ~
-26- 337-2164 (8CT-4858)
E~A~PL~ 7
The procedure of Example 3 is followed
substituting a dry blend of 54 parts of polyester (PBT,
poly(l,4-butylene terephthalate), Valox- 315), 36 parts
of polyphenylene ether (PPE) (epoxy functionalized) and
10 parts of CSiM modifier ~(Si/PS)-MMA wt. ratio of
70:30) prepared by the method of Example 1, and molding
at 280C. There is no agglomeration in the blends, good
rubber dispersion and good blend morphology with the
CSiM modifier appearing aQ separate spherical particles.
No delamination or surface mottling are seen. Properties
are summarized in Table 2.
CO~PA~ATIVg EXA~PL~ 7A~
The procedure of Example 7 is followed
omitting the CSiM modifier. Properties are summarized
in Table 2.
Example 7 when co~pared with Comparative
Example 7A* demonstrates the good ductility and that
polyorganosiloxane/polyvinyl-based CSiM modifiers can
impart to PBT/PPE blended thermoplastic molded articles.
Additionally, Example 7 shows no agglomeration, no
delamination, no surface mottling and markedly improved
rubber dispersion and blend morphology.
6J` ~ 2
-27- 337-2164 ~8CT-4858)
TABL~. 2
Co~POsitions Co~prising Polyester, PPE and CSi~
EXAMPLE 1 _7A*
Polyeqter A 54 54
PPE (8poxy Functionalized) 36 36
CSiM 10
Tensile Yield Strength (psi) 7115
Tensile Break Strength (psi)
Elongation Break Strength (%) 49
Notched Izod @ 25C
(ft-lbs/in) 2.14 0.5
A - poly(l,4-butylene terephthalate) - Valox~ 315 -
General Electric Company
8 - (Si/PS)-~MA wt. ratio of 70:30, Example 1
~33~
-28- 337-2164 (~CT-~858)
e~A~pL~ R
The procedure of Example 3 is followed
substituting a dry blend of 47.55 parts of polyester
(P8T, Valox- 295, General Electric Company), 30.0 parts
of polycarbonate (Lexan^ 141, General Electric Company),
0.45 part of a stabilizer package, 12 parts o~ CSiM
((Si/PS)-MMA wt. ratio of 70:30) prepared by the method
of Example 1 and 10 parts of glass filler; and u~ing a
2.S" Prodex II single screw extruder. The molded
articles are tested and yield a YI of 9.7, a ~urface
gloss (60) of 72~6, a specific gravity of 1.30 and a
one-eighth inch notched Izod of 1.6 ft-lb~/in. No
delamination, no surface mottling, no agglomeration,
good rubber dispersion and good bIend morphology are
lS seen from this glass filled high impact system
comprising PBT, polycarbonate, stabilizer and the CSiM
modifiers of the present invention.
E~A~PL8 9
The procedure of Example 3 is followed
substituting a dry blend of 46 parts of PBT (Valox-
315), 30 parts of polyphenylene ether (PPE) (vacuum
vented), 14 parts of polycarbonate (~ILEX- - General
Electric Company) and 10 parts of CSiM ((Si~PS)-MMA wt.
ratio of 70:30) prepared by the method of Example 1.
Morphology is illustrated in FIG. 3. The~e is good
rubber diQpersion, good blend morphology with the impact
modifier (1) appearing as separate spherical particles
and no agglomeration in the PPE (3)/PBT (5)/PC (7)
blend. No delamination or surface mottling are seen.
Properties are summarized in Table 3.
CO~PARATIVE EaA~PL~ 9A~
The procedure of Example 9 is followed
omitting the CSiM modifier. Properties are summarized
in Table 3.
2~33~2
-29- 337-2164 (8CT-4858)
~A~I.~ 10
The procedure of Example 9 is followed
substituting 10 parts of CSi~ ((Si/PS)-S-MMA wt. ratio
of 80:7:13) prepared by the method of Example 2 for the
CSiM. There is good rubber dispersion, good blend
morphology with the CSiM modifier appearing as separate
spherical particles and no agglomeration in the blends.
No delamination or surface mottling are seen. Properties
are summarized in Table 3.
~KAnpL~ 11
A well mixed dry blend of 97.5 parts (21 parts
of the final blend) of polyca~bonate (HILEX-) and 2.5
parts (0.55 part of the final blend) of CSiM ((Si/PS)-
MMA wt. ratio of 70:30) prepared by the method of
Example 1 is extruded. The resultant composition, 47
parts of PBT ~Valox- 315) and 31.45 parts of polyphenylene
ether (PPE) is extruded. Morphology is illustrated in
FIG. 3. There is excellent rubber dispersion with the
CSiM modifier (1) appearing as separate spherical
particles and no agglomeration in the PC phase of the
PBT (5)/PPE (3)/PC (7) blend.
Examples 9 and 10 when compared with
Comparative Example 9A* demonstrate the much improved
ductility that polyorganosiloxane/polyvinyl-based graft
MMA polymer modifier~ impart to PBT/PPE/PC blended
thermoplastic molded articles.
~30- 337-2164 (8CT-4858)
TABL~ 3
co~Positions Co~pri~in~_Pol~e~er, PPX, PC and CSi~
EXAMPLE 9 9A* 10 11
Polyester A 46 46 46 47
PPE (Vacuum Ve~ted) 30 30 3031.45
Polyc~rbonate 14 14 14 21
CSiM D 10 - - 0.55
CSiM - - 10
Tensile Yield Strength (p~i)7101 - 6456
Elongation Break Strength (%)41 - 45
Notched Izod @ 2SC
(ft-lbs/in3 1.3 0.6 1.1
A - poly(l,4-butylene terephthalate) - Valox- 315 -
General Electric Company
B - poly~bisphenol-A carbonate) - Lexan- 141 -
General Electric Company
C - (Si/PS)-MMA wt. ratio of 70:30, Exa~ple 1
D - (Si/PS)-S-MMA wt. ratio of 80:7:13, Example 2
2 ~ 4 ~
-31- 337-2164 (8CT-4858)
In the foregoing examples, the degree of
swelling can be determined in the following fa~hion:
A prepared polyorganosiloxane-based latex is
coagulated by adding it to about 4 times its volume of
methanol and water (1:1 volume ratio) containing 1 wt.
percent MgSO4. The precipitated rubber is washed and
vacuum-dried at 70C overnight. Approximately 1 g of
the dry silicone-based rubber is immersed in 100 ml
toluene for 20 to 24 hours at ambient temperature and
allowed to swell. The excess toluene is separated by
decantation. The swelled polymer is vacuum-dried at
60C overnight, and the resulting polymer is weighed.
The degree of swelling is calculated as: DS = ((weight
of swelled polymer) - (weight of dry polymer)) divided
by (weight of dry polymer).
Graft Efficiency can be determined by weighing
dry multi-stage polyorganosiloxane-based graft polymer
in a weighed thimble which is Soxhlet extracted by
acetone for 20 to 22 hr. A~ter vacuum-drying, the
residue of the extraction is weighed. The graft
efficiency is calculated as: GF (%) = ((weight of
grafted monomer(s) x 100) divided by (weight of total
monomer(s) polymerized).
All patents and applications mentioned above
are hereby incorporated by reference.
Many variations of the present invention will
suggest the~selves to those skilled in this art in light
of the above, detailed description. All such obvious
variations are within the full scope of the appended
claims.
