Note: Descriptions are shown in the official language in which they were submitted.
8CH-2428
This invention relates to improved compositions of
a polyphenylene ether resin and an alkenyl aromatic resin
that is modified with an EPDM rubber. Reinforced and flame-
ret:ardant compositions are also provided.
The polyphenylene ether resins are a family of engine-
ering 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 corresponding phenols
or reactive derivatives thereof. By way of illustration,
certain of the polyphenylene ethers are disclosed in Hay
U.S. 3,306,874 and 3,306,875 dated February/28/1967, and
in Stamatoff, U.S. 3,257,357 and 3,257,358 dated June
21, 1966. In the Hay patents the polyphenylene 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 ethe~ with styrene type compounds, are
found in Fox, U.S. 3,356,761 dated June 28, 1966; Sumitomo,
U.K. 1,291, 609, Bussink et al., U.S. 3,337,499 dated
August 22, 1967; Blanchard et al., U.S. 3,219,626 dated
November 23, 1965; Laakso et al., U.S. 3,342,892 dated
September 19, 1967; Borman, U.S. 3,344,166 dated September
26, 1967; Hori et al., U.S. 3,384,619; Faurote et al.,
` .
- . . , . . -............... . -
. .. .... :. ~ .. : ~ . - . : .
8CH-2428
~199~:
U.S~ 3,440,217 dated April 22, 1969; and disclosures re-
lating to metal based catalysts which do not include
am:ines, are known from patents such as Wieden et al., U.S.
3,442,885 dated May 6, 1969 (copper-amidines); Nakashio
et al., U.S. 3,573,257 (metal-alcoholate or - phenolate);
Kob~ ~ i et al., U.S. 3,455,880 dated July 15, 1969
(~4~t chelates); and the like. In the Stamatoff patents,
the polyphenylene ethers are produced by reacting the
corresponding 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 discloses polyphenylene ether-styrene
resin compositions.
The term "alkenyl aromatic resin" includes polymers
and copolymers of styrene, alpha methyl styrene, chlo-
rostyrene,ethylvinylbenzene, divinylbenzene, vinylnaphth-
alene, and the like.
The term "EPDM" includes rubbery interpolymers
of a mixture of mono-olefins and a polyene. Preferred
types are those rubbery interpolymers of ethylene, an
alpha-olefin, and a polyene. Rubbery interpolymers
of ethylene, propylene, and a polyene are especially
- 2 A -
-: -. - , - :- . . -- ............................ :, . :
:- , - ., . - - : ,
8CH-2428
~11992
preferred.
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. 3,3~3,435 dated May 14, 1368, dis-
closes rubber-modified styrene resin-polyphenylene ether
resin compositions wherein the rubber component is of
the unsaturatea 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 are
improved.
Nakashio et al. U.S. 3,658,945 dated April 25,
1972 discloses that from 0.5 to 15% by weight of an
EPDM-modified styrene resin may be used to upgrade the
impact strength of polyphenylene ether resins. In
Cooper et al., U.S. 3,9~3,191 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.
~ - 2 B -
: ., , - . . : ~
~ 9~2 8CH-2428
The EPDM rubber in the Cooper et al. compositions is com~risPd
substantially of particles in the range of 3-8 microns.
There is no teaching of EPDM rubber having smaller particle
slze .
The impact strength of the Cooper et al. compositions
is superior to that of a polyphenylene ether resin alone or
that of similar compositions comprised of unmodified poly-
styrene; however, the impact strength of the Cooper et al.
compositions is inferior to that of similar compositions
comprised of polystyrene modified with polybutadiene rubber,
such as a composition known as FG-834, available from
Foster-Grant Co.
As is disclosed in U.S. 3,981,841 dated September
21, 1976, the impact strength of the Cooper et al. composi-
tions can be improved by incorporating therein impact
modifiers such as an emulsion-grafted EPDM polystyrene
copolymer.
We have now found that a composition of a poly-
phenylene ether resin and an alkenyl aromatic resin
~0 modified with an EPDM rubber comprised of particles having
a median diameter less~than about two microns, is a very
useful thermoplastic molding material having good thermal
oxidative stability and good impact strength.
We have further found that the impact strength of
the polyphenylene ether resin and small particle EPDM
rubber-modified alkenyl aromatic compositions may be
influenced by several different factors. Thus we have
found one such factor which relates to the molecular
weight of the modified alkenyl aromatic resin. Impact
strength properties are maximized when the modified
alkenyl aromatic resin has an intrinsic viscosity, as
measured in chloroform at 30C, of at least 0.50 dl/g.
- 3 -
.. . .. . . .
8C~I-2428
1992
A further factor concerns the addition of a small amount
of mineral oil to the mixture of EPDM rubber and alkenyl
aromatic resin during the polymerization of the alkenyl
aromatic resin which greatly increases low temperature
impact strength of polyphenylene ether resin and EPDM-
modified alkenyl aromatic resin compositions without
impairment of room temperature impact strength, heat dis-
tortion temperature, or other properties.
Although heat distortion temperature, and most other
properties of polyphenylene ether risen and small-particle
EPDM rubber-modified alkenyl aromatic resin compositions
are not greatly affected by the EPDM rubber content of
the modified alkenyl aromatic resin, at least over the range
of about 6 to 18% by weight, Izod and Gardner impact
strengths, particularly Izod impact strength, are strongly
sensitive to EPDM rubber concentration. Thus we have found
that an EPDM rubber content of at least about 8% by weight
permits an impact strength comparable to that of an alkenyl
aromatic resin modified with unsaturated rubber, such as
polystyrene modified with FG-834 to be achieved. As a
still further factor influencing the impact strength of
these compositions of a polyphenylene ether resin and a
small-particle EPDM rubber-modified alkenyl aromatic
resin, we find that a certain minimum degree of cross-
linking in the rubber particles is desirable. The degree
of crosslinking is measured by the percent of rubber-
modified alkenyl aromatic resin which is insoluble in
toluene. Good impact strengths may be obtained when at
least about 2% by weight of the rubber modified a~kenyl
aromatic resin comprises toluene-insoluble gel. We have
additionally found that impact strength of these compositions
is influenced by the polypropylene content of the EPDM
8CH-2~28
terpolymer, whereby the input strength may be maximized by
limiting the propylene content to not more than about 45%
by weight.
A major aspect of this invention con~erns the provision
of improved compositions that are based on polyphenylene
ether resins and modified alkenyl aromatic resins.
Another aspect of this invention concerns the provision
of molding compositions and molded articles that are based
on a polyphenylene ether resin and an EPDM modified alkenyl
aromatic resin and that have improved thermal oxidative
stability.
Still another aspect of this invention concerns the
provision of molding compositions and molded articles that
are based on a polyphenylene ether resin and an EPDM modi-
fied alkenyl aromatic resin and that have improved impact
strength.
It is also an object of this invention to provide
the above-described, improved molding compositions in
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
the following compositions.
Preferred types will include thermoplastic composi-
tions which comprise:
(a) from 20 to 65% by weight of a polyphenylene ether
resin and
(b) from 35 to 80% by weight of an alkenyl aromatic
resin that is modified with an EPDM rubber comprised of
particles having a median diameter less than about two
microns. The EPDM rubbers, that is, rubbery interpolymers
comprising mixtures of mono-olefins and a polyene, include
those prepared from ethylene, an alpha-olefin, and a polyene.
8CH-2428
92
Preferred types comprise 10-90 mole percent of ethylene,
10-~0 mole percent of an alpha-olefin containing 3-16
carbon atoms, and 0.1-12 mole percent of a polyene that
is c~ non-conjugated cyclic or open-chain diene having
5-20 carbon atoms. Especially preferred are those alpha-
olefins having 3-10 carbon atoms and nonconjugated cyclic
or open-chain dienes having 5-10 carbon atoms.
Useful EPDM rubbers include the ethylene-propylene-
ethylidene norbornene terpolymer and those described in
Ritchie, Vinyl and Allied Polymer, Vol. 1, Page 121 (1968).
The preferred EPDM rubbery interpolymers are those comprised
of ethylene, propylene, and 5-ethylidene-2-norbornene; of
ethylene, propylene, and 1,4-hexadiene; and of ethylene,
propylene, and dicyclopentadiene. Preferred modified
alkenyl aromatic resins will include from about 4 to about
25~ by weight of rubbery interpolymer.
The rubber particle size can be measured by several -
different methods. One method is the use of transmission
electron micrograph, with appropriate corrections to allow
for the fact that the photograph obtained does not show
particle diameters but rather sections of particles. Making
the photographs and measuring the particles are rather ted-
ious.
Another method, commonly employed, is to estimate
particle size visually by means of an optical microscope.
The samples will be in a cinnamaldehyde dispersion, which
may cause the EPDM rubber particles to swell slightly, so
that the observed particles diameters will be those of the
swollen particles. The samples are photographed under
magnification. A strip of the photograph is selected at
random and the sizes of a sufficiently large number, e.g.,
100, of particles are estimated and a size distribution is
obtained. From the distribution a median particle size is
-- 6
,, . . - .
8CH-2428
9~;~
estimated. The median particle diameter is that for which
the sample contains the same number of larger and of smaller
particles. See the appended examples.
Particle diameter size can also be measured by means
of a Coutler Counter, a well known electronic counting
device for measuring the volume size distribution of fine
particulate dispersions. The Coutler Counter registers
a number average particle diameter which normally corres-
ponds very closely to the median particle diameter. When
the Coutler Counter is used with a 100 micron orifice,
smaller particles tend not to register and the determined
average number particle size will be from about 5 to 35~
higher than the visually determined median particle diameter.
When a 30 micron orifice is used, larger particles tend to
be excluded and the determined average number particle size
will be from about 10 to 30~ lower than the visually det-
ermined medium particle size. Additional information re-
garding particle size measurement with a Coulter Counter
can be found in James, "Particle Size Measurement of the
Dispersed Phase in Rubber Modified Polystyrene, "Polymer
Engineering and Sciènce, July, 1968, Vol. 8, No. 3, pages
241-244.
The useful EPDM rubbers of this invention have a
median or number average particle size less than about two
microns, preferably in the range of from about 0.5 to 1.5
microns, as determined by the above-mentioned cinnamaldehyde
technique, and confirmed if necessary or desirable by a
Coulter Counter using a 30 micron orifice.
The alkenyl aromatic resin should have at least 25~
of its units derived from an alkenyl aromatic monomer of
the formula:
-
.
~ ~CH-2428
CR = CHR2
R5
R6, ~ _ R
wherein Rl and R2 are selected from the group consisting of
hydrogen and lower alkyl or alkenyl groups of from 1 to 6 :
carbon atoms; R3 and R are selected from the group consisting
of chloro, bromo, hydrogen, and lower alkyl groups of from
1 to 6 carbon atomsl 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 - - - (CH~)m - R
: wherein the dotted lines each -represen:t single or a double
; ~ carbon to carbon bond; R7 and R8 taken together represent a
: o O
11 11 9
C - O - C linkage; ~ is selected from the group consisting
: ~ of hydrogen, vinyl, alkyl of from 1 to 12 carbon atoms,
alkenyl of from 1 to 12 carbon atoms, alkylcarboxylic of
from 1 to 12carbon 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 is an integer o~
.
` from 0 to about 10. Examples include maleic anhydride,
.. ..
- 8 -
.,........... ~ , . :
.. . . .
8CH-2428
i92
citraconic anhydride, itaconic anhydride, aconitic anhydride,
and the like.
The alkenyl aromatic resins include, by way of example,
homopolymers such as homopolystyrene and monochloropoly-
styrene, and styrene-containing copolymers, such as styrene-
chlorostyrene copolymers, styrene-bromostyrene copolymers,
the styrene acrylonitrile-~-alkyl styrene copolymers, styrene-
acrylonitrile copolymers, styrene butadiene copolymers, sty-
rene acrylonitrile butadiene copolymers, poly-~rmethylstyrene,
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. 3,971,939 dated July 27,1976, U.S. 3,336~267 dated
August 15, 1967, and U.S. 2,769,804 dated November 6, 1956.
Polyphenylene ether resin blends having good impact
strength are obtained when the EPDM rubber-modified alkenyl
aromatic resins have a high molecular weight. Molecular
weight of the modified alkenyl aromatic resin is pro-
portional to its intrinsic viscosity, and maximum impactstrength properties are obtained when the molecular weight of
the modified alkenyl aromatic resin corresponds to an in-
trinsic viscosity, as measured in chloroform at 30C, of
at least 0.50 dl/g. Preferably the intrinsic viscosity
will be from about 0.70 to 1.2 dl/g.
The molecular weight of the modified alkenyl aromatic
resin can be increased in any of a number of known ways.
The reaction temperature, type and concentration of free
radical initiator, if any, solvent, etc., have known effects.
For example, molecular weight goes down as reaction tem-
perature or initiator concentration goes up. Chain transfer
agents or regulators, such as carbon tetrachloride, carbon
,
. - ; . . . -,,.: ~ .
. ,.. ~... . .
8C~-2428
tetrabromide, mercaptans (n-butyl mercaptan, n-dodecyl mer-
captan, tert-dodecyl mercaptan), are often used to control
the molecular weight. Discussions of some ~actors affecting
molecular weight appear in Flory, "~rinci4~s of Polymer
Chemistry" (Cornell University Press, 1952), pages 132-148,
and in Odian, "Principles of Polymeri~ation" (McGraw-Hill,
1970), pages 161-245.
Polyphenylene ether resin blends having good low tem-
perature impact strength are obtained when the compositions
comprise small-particle EPDM rubber-modified alkenyl aromatic
resins containing a small amount of mineral oil. Preferably
the modified alkenyl aromatic resins contains from about 1
to 3% by weight of mineral oil. The mineral oil is pre-
ferably added to the mixture of rubber and styrene before
or during the polymerization reaction.
The mineral oils useful in this invention are of the
type known as white mineral oils. They are a complex
mixture of saturated paraffinic and naphthenic hydrocarbons,
and are free of aromatic compounds, sulfur-containing
compounds, acids, and other impurities. White mineral oils
are available in a wide range of viscosities, and the
useful oils have Saybolt viscosities ranging from about 50
to 350 at 100 F. Examples of suitable oils are PROTOL TM,
GLORIA TM,and KAYDOL TM white minerail oils manufactured
by Witco Chemical Company. KAYDOL, which has a Saybolt
viscosity of 350 at 100 F and a pour point of 0 is preferred.
A more detailed description of useful mineral oils can
be found in U.S. 2,619,478 dated November 25, 1952.
In polyphenylene ether resin and small-particle EPDM
rubber-modified alkenyl aromatic resin compositions, the
impact strength relates to EPDM rubber concentration. In
order to have good impact strength, i.e., impact strength
-- 10 --
~. " - .
.
8CH-2428
comparable to that of polystyrene modified with FG-834,
the EPDM rubber content should be at least 8% by weight.
Preferably the EPDM rubber content is from about 8 to 18
by weight.
Polyphenylene ether resin blends having a good impact
strength are obtained when the small-particle EPDM rubber-
modified alkenyl aromatic resins contain at least about 2%
by weight, preferably from about 2 to 30~ by weight, of
tolueneinsoluble gel.
Polyphenylene ether resin compositions having especially
good impact strength are obtained when the EPDM rubbers in
the small-particle EPDM rubber-modified alkenyl aromatic
resins have a propylene content not greater than about 45%
by weight, preferably in the range of about 30 to 45~ by
weight.
The preferred polyphenylene ethers are of the formula:
~
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, hydro-
carbonoxy radicals, and halohydrocarbonoxy radicals having .
- . - .
- . . .: . . : .
8CH-2428
at least 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 modified with an EPDM rubber
may be prepared by dissolving the rubber interpolymer 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 reacted
to form said EPDM-modified alkenyl aromatic resin.
The compositions of the invention can also include other
ingredients, such as flame 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 re-
inforcement, 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 under-
stood that, unless the filler adds to the strength and
stiffness of the composition, 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 dis-
tortion temperature.
~lthough it is only necessary to have at least a rein-
forcing amount of the reinforcement present, in general,the combination of components ~a~ and (b) will comprise
from about 10 to about 20 parts by weight and the filler
- 12 -
8CH~2428
92
will comprise from about 10 to about 90 parts by weight of
the total composition.
In particular, the preferred reinforcing fillers are
of glass, and it is preferred to use fibrous glass fila-
ments comprised of lime-aluminium 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 flame blowing, or by
mechanical pulling. The preferred filaments for plastics
reinforcement are made by machanical pulling. The filament
diameters range from about 0.000112 to 0.00075 inch, but
this is not critical to the present invention.
In general, the best properties will be obtained if the
sized~filamentous glass reinforcement comprises from about 1
to about 80% by weight based on the combined weight of glass
and polymers and preferably from about 10 to about 50~ by weight.
: '
:.
- , . . . . . . . - ............ , . , . ~ - .
' ' . ~ . , ' . ' ,., ' ' '; : ' - ' - . ' ' '', ~ ' -
~450
H-24~ 9 ~ 2
I!
1 IEspecially preferably the glass will comprise from about 10 t~
2 ~ about 40~ by weight based on thP combined weight of glass and
3 ~, resin. Generally, for direct molding use, up to about 50~/O of
4 ll glass càn be present without causing flow problems. However,
5 ¦l it is useful also to prepare the compositions containing
6 ¦l substantially greater quantities, e.g., up to 70-80% by weight
7 1¦ of glass. These concentrates can then be custom blended with
8 ¦I re~in compo~itions thst are not glass reinforced to provide any ¦
9 ¦I desired glass content of a lower valueO
~
11 I The length of the glass filaments and whether or
12 I not they are bundled into fibers and the fibers bundled in
13 turn to yarns, ropes or rovings, or woven into mats, and the
14 I like, are also not critical to the invention. ~lowever, in
I preparing the present compositions it is convenient to use
16 ¦ the filamentous glass in the form of chopped strands of from
17 l, about 1/8" to about 1" long, preferably less than 1/4" long.
18 1l In articles molded from the compcsitions, on the other hand,
19 ~¦ even shorter lengths will be encountered because, during
ll compounding, considerable fragmentation wlll occur. This is
2~ ¦I desirable, however, because the best properties are exhibited
22 I by thermoplastic injection molded articles in which the fila-
23 ¦ ment lengths lie between about 0,000005" and 0.125".
24 1l / `
2~
26
27 1 /
I -14-
, .... .. _... i - _ .
-450
CIi-24
il ~L1~199Z
I, .
l ¦ Because it has been found that certain commonly
2 1 used flammable sizings on the glass, e.g., de~trln~zed starch
3 ~ or synthetic polymers, contribute flammabiLity often in greater
4 ¦¦ proportion than expected from the amount present, it is pre-
¦ ferred to use lightly sized or unsized glass reinforcements in
6 ¦ those compositions of the present invention which are flame-
7 I retardant. Sizings, if present, can readily be removed by
8 ¦ heat cleaning or other techniques well known to those skilled
9 ¦¦ in the art,
l ~,
ll It is a preferred feature of this inven~ion also to
12 ¦, provide flame-retardant thermoplastic compositions, as defined
13 ¦ above, by modifying the composltion to include a flame-retardant
14 I additive in a minor proportion but in an amount at least
sufficient to render the composition non-burning or self-
16 ¦ extinguishing.
17 l
18 I A preferred feature of the invention is a flame-
l9 li retardant composition as above defined, which also includes a
i halogenated organic compound, a halogenated organic c~mpound
21 !¦ in admixture with an antlmony compound, elemental phosphorus,
22 ¦¦ a phosphorus compound, compound6 containing phosphorus-nitrogen
23 , bonds, or a mixture of two or more of the foregoing.
24 l, /
1' /
26 ,
27
-IS- ~
_ _... . .. ,.. 1, _. ..... .. _.. _.. _........ . . _ . _, . . ~ _. _ _
_ - -- ..... ~ ., .
~E-450 ~, ¦
t8~H~.2L ,)~
I When used herein, the terms "non-burning", "~elf-
2 , lextinguishing", and "non-dr1pping" are used to descrlbe eompo-
3 1 sitions which meet ~he standards of ASTM test method D-635
4 ¦l and Underwriters' Laboratories Bulletin No. 94. Another
5 ¦¦ recognized procedure to determine flame resistance of resinous
6 I compositions is the Oxygen Index Test or LOI (Limiting Oxygen
I Index). This test is a direct measure of a product's combus-
8 jl tibility based on the oxygen content of the combustion atmo-
9 Ij sphere. Appropriate spec~mens are placed ~n a co~bustion
¦ ch~nney, and the oxygen is reduced stepwise until the material
11 I no longer supports a flame. The LOI Is defined as the percen~
12 ¦ oxygen times 100 dlvided by the ~um of the percentages of
13 I nitrogen and oxygen in the gas uced to burn the material under
14 ¦ test. Further detalls of the Oxygen I~dex Test are found in
I ASTM test Method D-2863. The composltions of this invention
16 Il which contain flame-retardant additives in the specified
17 ¦l amounts have a substantlally higher oxygen index and thus are
18 li much less combustible than the control~
19 ~
20 ll The flame-retardant additive3 useful in this inven-
21 1I tion comprise a family o~ chemical compounds well known to ¦
22 i those skilled in the art~ Generally speaking, the more important
23 lj of these compounds contain chemical elements employed for their
24 1l ability to impart flame resistance, e,g,, bramine, chlorine,
¦ antimony, phosphoru~, and nitrogen. It i~ preferred that the
26 1'
27 1 /
1! -16-
~-24~ 2
~1 . ll ,
Il .
1 ¦I flame-retardant additlve comprise a halogenated organic com- ~
2 ¦I E~ound (brominated or chlorinated3; a halogen-containing organic ¦ , -
3 oampound ln admixture with ant~mony oxide; elemental phosphorus
4 or a phosphorus compound; a halo~en-containing compound in
admixture with a phosphorus compound or compounds containing
6 ~I phosphorus-nit~ogen bonds; or a mixture of two or more of the
7 l; foregoing. .
8 11 .
9 1¦ The amount of flame-retardant additive used i6 not
lo !I critical to the invention, so long as it is present in a minor
11 ¦i proportion based on the polyphenylene ether-modified alkenyl aro-
12 1¦ matic polymer eomposition -- ma~or proportions will detract from
13 1I physical properties -- but at least sufficient to render the
14 I composition non-burning or self-extinguishing. Those skilled
I in the art are well sware that the amount will vary with the
16 ¦ nature of the polymers in the c~mposition and with the efff~ncy
17 ll of the additive, In general, however, the amount of additive
18 ¦¦ will be from about 0,5 to 50 parts by weight per hundred parts
19 ~ I of components (a) plus (b). A preferred range will be from
I about 1 eo 25 parts,and an especially preferred range will be
21 ¦ from about 3 to 15 parts of additive per 100 parts of (a) plus
22 I (b). Smaller amounts of compounds highly concentrated in the
23 j~ elements responsible for flame retardance will be sufficient,
24 ¦1 e.g., elemental red phosphorus will be preerred at about .
~ 25 1!'
26 11 /
27
' ~ 11 ,1
'I -17-
'` . ' ' ' ':' ',. ' ' ' :
;` . ' . ~ :: ,
. - . . : ... ..
-450 ll
CH-242 ¦; ,
9~2 I,
,
1 1 0.5 to 10 p~rts by weight per hundred p~rt~ of {i), (ii), and
2 1 (III), while phosphorus in the fo~l of triphenyl phosphate
3 1 will be used at about 3 to 25 parts of phosphate per part of
4 1 (i), (ii), and ~iii), and so forth. Halogena~ed aromatics
~ will be used at about 2 to 20 parts and synergi3ts, e.g.,
6 ¦1 antimony oxide, wlll be used at about 1 to 10 parts by ~eight
7 ¦I per 100 parts of components ~), (ii), and ~iiij.
8 '' .
9 ~ Among the useful halogen-containing compounds are
li those of the fonmula
Il 1'
( ( Ar ~ l ~ Ir
16
17 li wherein n is 1 to 10 and R is an alkylene, alkylldene, or
18 ¦ cycloaliphatic linkage, e,g., methylene, ethylene, propylene,
19 li~ isopropylene, isopropylidene, butylene~ isobutylene, amylene,
.~ , 1, .
l cyclohexylene, cyclopentylidene, and the like; or ~ linkage
21 I selected from the group consisting of ether; carbonyl; amine;
22 I a sulfur-contain~ng linkage, e.g., sulfide, sulfoxide, or
23 I sulfone; carbonate; a phosphorus-containing linkage; and the
24 ¦ like. R can also consist of two or more alkylene or alkylidene
~ /
26 ~
27 1 /
11 , .
; I -18-
,. I , .
_.......... =_ _ ..
" ~ _~ ' . " i - '; - ~t ' 't '' , ~ J
:.
,' - . , : ' .
', ' - .,.: . .. ,' ' . :
;H~242~ ' ~
9~
I . .
1 I linkages connected by such groups as aromat~c, amino, ether,
2 I ester, carbonyl, sulfide, sulfoxide, sulfone, a phosphorus- ¦
3 ¦¦ containing linkage, and the llke, R can be dihydrlc phenol,
4 ¦¦ e,g,, bisphenol-A, carbonate linkage~ Other groups which are
¦I represented by R will occur to those skilled in the art. Com- ¦
6 1¦ pounds of this type are disclosed in U.S. 3,647,747 dated
7 1¦ March 7, 1972, and u.S. 3,334,154 dated Aug/1/1967.
8 j .
g 1l Ar and Ar' are mono- or polycarbocyclic ar~matic
1I groups such as phenylene, biphenylene, terphenylene, naphthylene,
ll jl and the like. Ar and Ar' may be the same or different.
12
13 I X is a monovalent hydrocarbon group exemplified by
14 ¦ the following: alkyl groups, such as methyl, ethyl, propyl,
I isopropyl, butyl, decyl, and the like; aryl groups, such as
16 ¦I phenyl, naphthyl, biphenyl, xylyl, tolyl, and the like; aralkyl
17 1 groups, such as benzyl, ethy1phenyl, and the llke; cyclo- I
18 ¦, aliphatic groups, such as cyclopentyl, cyclohexyl, and the like;
19 1 as well as monovalent hydrocarbon groups containing inert sub-
20 ll stituents therein. It will be understood that where more than
on~ X is used, they may be alike or different.
22
23 I Y is a substituent selected from the group consistlng
24 1l of organic, inorganic, and organometallic radicals, The sub-
25 ¦I stituents represented by Y include (1) halogen, e.g., chlorine,
26
27 ` /
` ; ! -19- 1
.. . . ..
.. . .. .
-450 1! 1
~H~242~ 1 ! `
1 ~ 2 l :
.:
1 bromiine, lodine, or fluorine, (2) ether groups of the general
2 fonmula OE, wherein E is a monovalent hydrocarbon radical
3 ¦ similar to X, (3) monovalent hydrocarbon groups of the type
4 repre~iented by R, and (4) other substituents, e,g.~ nltro~
cyano, etc., said substituents being essentlally inert provided
6 there be at least one and preferably two halo~en at~ms per
7 aryl9 e.g., phenyl, nucleus,
8 1
9 1 T~e letter d represents a whole number ranging from
1 1 to a maximum equivalent to the number of replaceable hydrogens
11 ¦ substituted on the aromatic rings comprising Ar or Ar'. The
12 1 letter e represents a whole number ranging from 0 to a maximilm
13 ¦ controlled by the number of replaceable hydrogens on R, The
14 letters a, b, and c represent whole numbers including 0. When
b is not 0, neither a nor c may be 0, and when b is 0, either
16 a or c, but not both, may be 0. Where b is 0, the aro¢iatic
17 ¦ groups are Joined by a direct carbon-carbon bond.
8 11
19 I The hydroxyl and Y substituents on the aromatic
! group~, Ar and Ar!, can be varied in the ortho, meta, or para
21 ! poQitionS on the aromatic rings, and the groups can be in any
22 ! possiible geometric relatlonship with respect to one another.
, ~ 23 ! ~
24 1 /
11 .
! 26 ~ /
27 ll /
~: , . . . .
' . : ' ' . ~ ' '-.
$ `
8~ 24
ll
1 ¦ Included within the scope of the above formula are
2 1 di-aromatics of whlch the following are representative:
3 1
4 ¦ 2,2-bis-(3,5-dichlorophenyl)propane
.~ I bis-(2-chlorophenyl)methane
6 l bis-(2,6-dibromophenyl)methane
7 ¦ 1,1-bLs-(4-iodophenyl)ethane
.~8 1,2-bis-(2,6-dichlorophenyl)ethane . :~
;~ l,l-bis-(2-chloro-4-iodophenyl)ethane.
l,l-bis-(2-chloro-4-methylphenyl)ethane
11 l 1,1-bis-(3,5-dichlorophenyl)ethane
12 j 2,2-bis-(3-phenyl-4-bromophenyl)ethane
13 l 2,3-bis-(4,6-dichloronaphthyl)propane
14 l 2,2-bis-(2,6-dichlorophenyl)pentane
2,2-biq-(3,5-dichromophenyl)hexane
16 bis-(4-chlorophenyl)phenylmethane
17 bis-t3,5-dichlorophenyl)cyclohexylmethane
18 bis-(3-nitro-4-bromophenyl)methane .
19 l bis-(4-hydroxy-2,6-dichloro-3-methoxyphenyl)methane
; 20 l 2,2-bis-(3,5-dlchloro-4-~ydroxyphenyl)propane
2 2,2-bis-(3-bromo-4-hydroxyphenyl)propane
22 1
23 ! ~ The preparation of thèsè and other applicable bi- 24 1 phenylçi ~re known in theiart. In the above example6 sulfide,
sulfoxy, ~ind the like may be subst:ituted in pl~ice of the di-
26 1 v~ilent ~liphatlc group.
27 ~ / ` . .
l .
1 -21-
I .
~. . .... . _ .. .
~-450
CH-^24' ~ ¦¦
1 Included within the above structural formula are
2 ¦~ substituted benzenes exempllfied by tetrabromobenzene9
3 1I hexachlorobenzene, hexabromobenzene, and biphenyls such as
4 ¦ 2,2'-dichlorobiphenyl, 2,4'-dibromobiphenyl, 2,4'-dichloro
biphenyl, hexabromobiphenyl, octabromobiphenyl, decabromo-
6 biphenyl, and halogenated diphenyl ethers containing from
7 1 ~ to 10 halogen ato~s,
9 The preferred ~a~ogen compound~ for this invention
are aromatlc halogen compounds such as chlorinated benzene,
11 brominated benzene, chlorlnated biphenyl, chlorinated terphenyl,
12 brominated biphenyl, brominated terphenyl, or a compound
13 compri81ng two phenyl radicals separated by a divalent alkylene
14 group and having at least two chlorine or bromine atoms per
, 15 phenyl nucleus, or mixtures of at least two of the foregoing.
16
17 Especially preferred are hexabromobenzene and
18 ¦ chlorinated biphenyls or terphenyls, alone, or mlxed with
l9 l antimony oxide.
j
21 1 In general, the preferred phosphate compounds are
22 ! selected from the group of elemental phosphorus and organic
23 phosphonlc acid~, phosphonates, phosphinates, phosphonites,
24 phosphinites, phosphine oxides, phosphines, phosphites, and
j /
26 l~ /
27 11 / `
` I -22- ~
.
l ~
: .
E-450
BC~. 24
Il
1 1 phosphfltes. -Illustrative is triphenyl phosphine oxide Tl~e6e
2 1 can be used alone or mixed with hexabromobenzene or a chlorl-
3 ¦ nated biphenyl and, optionally, antimony oxide.
4 1
1 Typical of the preferred phosphorus compounds to
6 ¦ be employed in this invention would be those having the general
8 1 formuls
10 ~ ~0~
11 ! . I
12 1 Q
13 ! and nitrogen analogs thereof where each Q represents the same
14 ~ or different rsdicals including hydrocarbon radicals such as
11 alkyl, cycloalkyl, aryl, alkyl substituted aryl, and aryl
16 j substituted alkyl; halo~en; hydrogen; and combinations thereof
17 ! provided that at least one of ssid Q's is aryl. Typical
18 1 examples of suitable phosphates include, phenylbisdodecyl
19 ¦ phosphate, phenylbisneopentyl phosphate, phenylethylene hydrogen
¦¦ phosphate, phenylbis-(3,5,5'-trimethylhexyl phosphate), ethyl-
21 l dlphenyl phosphate, 2-ethylhexyl di~p-tolyl) phosphate, diphenyl
22 i hydrogen phosphate, bis(2-ethylhexyl) p-tolylphosphate, tritolyl
23 phosphflte, bis-(2-ethylhexyl)-phenyl phosphate, tri(nonylphenyl)
24 phosphate, phenylmethyl hydrogen phosphate, di(dodecyl) p-tolyl
phosphate, tricresyl phosphate, triphenyl phosphate, halogenated
26 1 triphenyl phosphate, d~butylphenyl phosphate, 2-chloroethyl-
27 l diphenyl phosphate, p-tolyl ~s(2,5,5'-trimethylhexyl) phosphate,
~23-
'; ' . . _
c ....
8CH-2428
2-ethylhexyldiphenyl phosphate, diphenyl hydrogen phosphate,
and the like. The preferred phosphates are those where each
Q is aryl. The most 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.
Also suitable as flame-retardant additives for this
invention are compounds containing phosphorus-nitrogen bonds,
such as phosphonitrilic chloride, phosphorus ester amides,
phosphoric acid amides, phosphonic acid amides, phosphinic
acid amides, tris(aziridinyl)phosphine oxide, or tetrakis
(hydroxymethyl) phosphonium chloride. These flame-retardant
additives are commercially available.
The compositions of the invention may be formed by
conventional techniques, that is, by first dry mixing the
components to form a premix, and then passing the premix
through an extruder at an elevated temperature, e.g., 425
` to 640P.
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
~ Ye~o~ ~e~
: '
' :
.
_ 24
:
~' ~ .' ' ' ' ~
: . . : ' '
length and put into an extrusion compounder with (a) the
polyphenylene ether resin, (b) the alkenyl aromatic resin
that is modified with a rubbery interpolymer of a mixture
of mono-olefins and a polyene, being comprised substantially
o~ small particles, and (c) the flame-retardant additives(s),
to produce molding pellets. The fibers are shortened and
predispersed in the process, coming out at less than 1/6"
long. In another procedure, glass filaments are ground or
milled to short lengths, are mixed with the polyphenylene
ether resin, the modified alkenyl aromatic polymer and,
optionally, flame-retardand additive, 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 times 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.
This invention is better understood by making
reference to the drawings:
Fig. 1 represents the relationship between median
rubber particle size and Izod impact strength in poly-
- phenylene ether resin compositions having polystyrene
modified by 10% by weight EPDM rubber.
Fig. 2 represents the relationship between median
rubber particle size and Izod impact strength for EPDM-
modified polystyrene.
Fig. 3 sets forth the relationship between polystyrene
intrinsic Viscosity and Izod impact strength for compositions
of polyphenylene ether resin and EPDM-modified polystyrene.
Fi~. 4, shows the relationship of percent by weight
of toluene insoluble gel to Izod impact strength, as compared
8C~-2428
to a control, for composl~lons of polyphenylene ether resin
and EPDM-modified polystyrene resin.
The following examples are set forth as further illus-
tration of the invention and are not to be construed as
limiting the invention thereto.
One hundred grams of Epcar 387 (an EPDM rubber manu-
factured by B.F. Goodrich Chemical Co.) was cut in small
pieces and dissolved, under nitrogen, in 900 g of styrene.
1.2 g of tert-butyl peracetate were added, and the solution
was transferred to a one-gallon reactor and stirred at 1600
r.p.m. by a 3-1/2 inch x 1/2 inch six-blade turbine. The
mixture was heated at 100C. After three hours at this
temperature a solution of 4.0 g of polyvinyl alcohol and
3.0 g of gelatin in 1500 ml of hot water was added, followed
by 8.0 g of di-tertbutyl peroxide. The stirrer speed was
reduced to 800 r.p.m., and the reactor was flushed with
nitrogen and sealed. The mixture was heated for one hour
at 100C, for two hours at 120C, for one hour at 140C,
and, finally, for two and one-half hours at 155C. The
mixtuxe was allowed to cool, and the EPDM-modified poly-
styrene, which was obtained in the form of fine beads, was
filtered off, washed thoroughly with hot water, and dried
in a vacuum oven.
The polymer was characterized by the following pro-
cedure:
' ~ thin slice of one of the beads was warmed on a
~ microscope slide with a drop of cimamaldehyde and photographed
j ~ at a magnification of 800X with an optical microscope. The
rubber particles ranged from about 0.75 to about 2 microns
in diameter. The sizes of one hundred particles from a
strip of the phot'ograph taken at random were estimated and
the size distribution obtained:
,y c~ c~
- 26 -
8CH-2428
0.5-1 micron - 42
1-1.5 micron - 31
1.5-2 micron - 19
2-2.5 micron - 8
From the distribution a median particle size of 1.2
m:Lcrons was estimated. A photograph taken by transmission
electron microscopy showed a median particle size of about
0.8 microns. Examination by means of a Coulter Counter
with a 100 micron orifice showed a number average particle
diameter of 1.3655 microns, and a weight average particle
diameter of 1.6517 microns.
A 5.00 g sample of the polymer was stirred for five
hours with 100 ml of methyl ethyl ketone, which dissolves
polystyrene but does not dissolve the EPDM rubber or poly-
styrene-rubber graft copolymer. The suspension was cen-
tifuged at 15000 r.p.m., and the clear liquid was poured
off and saved. The residue was resuspended in methyl
ethyl ketone and recentrifuged. The liquid was poured off
and the insoluble material was dried to constant weight in
a vacuum oven. It weighed 1.108 g, 22.2~ of the polymer.
The graft index, the ratio of percent insoluble in methyl
ethyl ketone to percent rubber added, was (22.2/10) or 2.2
The methyl ethyl solution was concentrated under
- vacuum and the dissolved polymer, nearly pure polystyrene,
was precipitated by addition to methanol. The intrinsic
viscosity of the polystyrene, measured in chloroform at
30~, was 0.86 dl/g.
A 1.000 g sample of the polymer was stirred for eight
hours with 20 ml of toluene, and the suspension was tran-
sferred to a tared centrifuge tube with an additional 25
ml of toluene. The suspension was centrifuged at 15000
r.p.m., and the liquid was poured off. The gel remaining
.
~ - 27 -
.~; ' '.
- - : ' ' ~ ~ . . .
~ 2 8CH-2428
was resuspended in toluene and again centrifuged. The
liquid was po red offfand the tube allowed to
drain in a-~hr~}ee~b~r over toluene. The tube was weighed
and dried. The weight of the dry toluene-insoluble gel
was 0.117 g (11.7%); the swelling index, defined as the
weight of the toluene-swollen gel divided by the weight of
dried gel, was 8.8.
The EPDM-modified polystyrene was compression molded
at 350 F into 1/8" test bars. It had a heat deflection
temperature of 214 F and a notched Izod impact strength of
0.6ft. lbs./-inch of notch.
Three hundred grams of PPO, 300 g of the EPD~-modified
polystyrene, 6 g of tridecyl phosphite, 18 g of triphenyl
phosphate, 0.9 g of zinc sulfide, and 0.9 g of zinc oxide
were mixed together and extruded at 575F in a 28 mm twin-
screw extruder. The extruded pellets were molded into
standard test pieces at 500F in a 3 oz. screw injection
molding machine. The notched Izod impact strength was
4.0 ft.lbs/inch of notch, and Gardner impact strength
was 200 in.lbs. A mixture of the same composition, but
with FG-834, a polystyrene modified with polybutadiene
(commercially available from Foster-Grant Co.) in place of
the EPDM-modified polystyrene, had Izod impact strength
of 4.5 ft.lb./inch of notch and Gardner impact strength
of 175 in. lbs. Another composition, prepared in the same
way with Taflite 925, an EPDM-modified polystyrene having
large rubber particles (commercially available from
Mitsui-Toatsu), had impact strength of 1.7 ft.lbs./in. of
notch and Gardner impact strength of only 5 in lbs.
Tensile bars from the compositions were aged in air
in an oven at 115C. Compositions made from FG-834 poly-
styrene become brittle after 53-56 days, those from the
- 28 -
.,
. -
.. .. ~. . . :
. . . . , .. ~ ~ .. .
8CH-242~
9;~
Taflite polystyrene became brittle after 67-70 days, while the
composition made with the small-particle EPDM polystyrene
described above remained ductile for more than 120 days.
Polymers were prepared from 100 g of EPDM rubber and 900
g of styrene by the procedure of Example I, but with different
stirring speeds between 200 and 1600 r.p.m. during the first
three hours of each run to produce polymers having different
average particle size. Some of the polymers were made with -
Epcar 387 and others with Epcar 587, a rubber also from B.F.
Goodrich Chemical Co. and having the same composition as 337,
but with a higher molecular weight. The impact strengths of
the modified polystyrenes, measured on compression molded 1/8"
bars, and of 50:50 compositions with PPO, extruded and molded
as describ~d in Example I, are shown in Table 1.
The effect of particle size on the impact strength of the
50:50 compositions is shown graphically in Fig. 1. It can be
seen that the impact strength of the 50:50 compositions in-
creases with decreasing particle size, and that compositions
having good impact strength (Izod impact strength~2~3.5 ft.
lbs/in of notch) were consistently obtained when the median
rubber particle diameter was less than 2.0 microns (cin-
namaldehyde method~.
The effect on the impact strength of the modified poly-
styrene alone was quite different, as shown in Fig. 2. Poly-
mers with small particles had low impact strength; the impact
strength increased with increasing particle size and reached
~` its maximum value at a size of about three microns. Thus, small
rubber particle size, i.e., below two microns, does not improve
the impact strength of EPDM-modified polystyrene compositions.
In view of this, the improved impact strength of PPO-EPDM
modified polystyrene compositions with small rubber particle
size is quite unexpected.
"
- 29 -
CE-~50
. (8CH-^ 28) ~ 9
I
TABLE 1.
: Izod Impac~ Strength ft.lb/in. notch~
. 5 1l Median particle
: ,I EPDMdiameter 50:50 Comp.
6 l Example Rubber (microns) ~ . Polystyrene
7 l, I Epcar 387 1.0 4.0 0.6 ¦.
8 1 II Epcar 387 1.1 4 3 i 0.6
g ¦¦III Epcar 387 1.2 4.1 0.6
¦¦IV Epcar 587 1.2 4.0 0.6
11 I V Epcar 587 1.9 3.9 1.0
12 ¦ VI Epcar 387 1.9 3.5 1.2
13 VII Epcar 587 2.9 3.0 1.7
14 VIII Epcar 587 3.9 2.9 1.4 ~ -
:. 15 IX Epcar 387 4.3 - 1.2
.; 16 1¦ X Epcar 387 7.0 1.5 1.1 .
. 17 1l
18 ___~_________~_______________ __ _______ _____________ ________ :
,'., 1~
1 ~
` 21 11 ,
:. 22 1 :
. 23
24
: 25
. 26 1
`` 27 `.l ~ 30 -
..,
,~ ',
.... _
GE-~5~ ~
~(8C~-24Z81 ~111992
,.,, ...
I',:IAM 1 ~1 :t1 x I ~
2 Polymers were prepared as described in Example I,
' 3 but wlt~ 8% instead of 10% EPDM rubber (80 g rubber + 920 ~
4 styrene) and with different stirring speeds, The Pf~ect of
5 ¦¦ particle size on impact strength is shown in the table below:
. 6 1
:. 7 1 . .
. ! TABLE 2
: 8 l
.. 9 ¦ . Izod Impact Strength
l (ft.lb/in. notch)
. EPDM Median Particle 50:50 Comp~
Example RubberSize (microns~ wt PP0 PolYstyrene
. 13 XI Epcar 387 0.8 3.2 0.5
XII Epcar 387 1.2 2.9 0.8
: 14
. 15 XIII Epcar 587 2.8 1.7 . l.l .
. 16 xrv Epcar 587 4.4 1.4 1.0
:~ 17 1 __~____________________________________________~________________
'18 il * Cinnamaldehyde method
` 19 ~
. 20 1¦ It can be seen that the results follow the same trend
;~ 21 ~ as at the higher rubber concentration, with the impact strength
22 1 of the 50:50 composition increasing with decreasing particle
23 ¦ size and with the impact strength of the modified polystyrene .
24 1 alone seeming to reach its maximum at about three microns.
`` 76
31 -
.--r
. ~ :
: GE-450
(8C~2428) .
.. .
~ Z
1 EXAMPLES XV-XVIII
2 The procedure of Example I was followed, but uslng
.~ 3 in addition to Epcar 387, other ethylene-propylene-ethylidlne
norbornene (ENB) terpolymers having different rstlos of ethylene,
propylene, and ENB, and a terpolymer of ethylene, propylene
6 and 1,4-hexadiene. The median diameter of th~ rubber particle~ I
. 7 in the products snd the impact strength of 50:50 composltion~ wlth
.. 8 PPO, ex~ruded and molded as descrlbed ln Example I, are shown
. in Table 3. Also included in Table 3 are values for extruded
:: 10 and molded control samples made fr~m FG_834 polystyrene modified
11 with polybutadiene rubber and from Taflite 925 EPDM-modifie~ .
~ 12 polystyrene having large rubber particleY.
., It can be seen that the medi~n p~rticle size ln all
14 c~8e8 ig less than two mlcron~ and that the Izod impact atrength
15 i8 at leaYt 80% of the control made from the poly~tyrene modi-
16 fied with polybutadiene rubber and much higher than that of a .
17 ¦ product of the same composit~.on made with Taflite 925.
18 i .
19 / .
/ :
21 / .
22 /
23 /
24 t
. 25 /
26
,. 27 /
. - 32~-
'~.
, . . . . . ~
:'~ . . .
:. . . : . - . . :
GE-4
(8CI~ 2~,~
~ 9~2
,. .
1 TABLE 3
2 . .
.: Izod Impact Strength of
. : 4 M~dian particle 50:50 Comp. with PP0
. ~ e~ EPDM dLameter(mieron~)
6 XV Epcar 387* 1.1 3.8
: 7 XVI Epcar 346* 1.4 3.6 -
81 XVII Vlstalon 6505** 1.8 3.5 .
9~ KVIII Nordel 1320*** 1.2 3.2 .
C-l+ FG-834 --- 3.9
12 C-2+ Taflite 925 5.1 1.5
~,_____~____________________________________________________________ .,
.~....... 13 .
:: 14
. * Ethylene-propylene-ENB terpolymer from B.F. Goodrich Chemical .
15Co~ :
: 16** Ethylene-propylene-EN8 terpolymer from Exxon Chemical Co.
~:. 17~ ~ Et~ylene~propylene-1,4-hexadiene terpolymer from E. I. duPont
18de Nemour~ Co.
. ~ Control
~',, 19 .
.:. 20 . .
`.: 21 . .
. 22 . .
23
.. ~4
r ~ 25 1
'` 26 1
.~ 27 ~ - 33 -
.~.,., , . ~
~.`, ~1 ` `'
, .:: :
~ GE-4
. (8CH-2428) ~ 9 9 2
''' ` . . .
1 EXAMPLE XIX
. Two hundred grams of the polymer produced in Example I,
3 200 g of PP0, 4 g of tridecylphosphite, I2 g of trlphenylphos-
. phate, 0.6 g of zinc sulfide, O. 6 g of zinc oxide, and 100 g of
. 5 Owens Corning 497BB 1/4" chopped glass fiber were blended, ex-
. 6 truded, and molded as described in Example I. Properties of
. ¦ the composition con~aining the glass iber are compared in the
8 1 table below with the properties of a slmilar composition but
. g , witho~t the reinforcing glass fibers:
',', 10 il
11 T~BLE 4 :
12
: 13 Tensile Flexural
. H.D.T.Strength Strength Flexural
14 Example Glass ~(p.s.i.) (p.s.i.~ M~dulus
C-3 4 None 246 8300 15,300 435,000
16 XIX 20~ 249 11400 15,800 725,000
~ 17 .
.. 18 . __________________________________________________________________
: 19 + Control
. .
21 ! It can be seen that the additlon of glass fiber pro- .
22; duces a ~mall ~ncresse in heat deflection temperature, tensile
~23 ~ strength, and flexural strength, and a large increase in the
. 24 rigidity of the compo8itionS as messured by lts flexural modulus.
,.;
/ .
1: ~
.. 26 ./ :.
.: 27 I
, I .' - 34 -
.' ' .
..
.,,. ~ .
- - . .. ... , . . - ~ , .. ~ .`, .. -
(8CH-242B) 111199Z
1 EXAMPLE XXV
2 EPDM modlfied polystyrene was prepared as descrlbed
3 in Example I. The median rubber particle diameter in the
4 product was estimated as 1.0 microns using the procedure of
Example I. The product was divided i~to three portions, and
6 each portion was extruded and molded with a different proportion
7 of PP0, as descrlbed in Example I. Composition XXVa contained
8 35 par~s of PPO, 65 parts of the EPDM-modified polystyrene,
9 and 7 parts o~ triphenyl phosphate. Composition XXVb contained
50 parts of PPO, 50 parts of EPDM-modified polystyrene, and
11 3 parts of triphenyl phosphate. Composition XXVc contained
12 65 parts of PP0, 35 parts of the polystyrene, and 6 parts of
13 triphenyl phosphate. Control blends of the same composition
14 ¦ were prepared using FG-834 polystyrene~ The Izod impact -
15 ¦ strengths of the compositions are shown below:
16
17 , TABI~ 8. -
` 18 1~ -
1~ ' . .
, Izod Impact Strength
Composition _ ~ft.lbs/in of notch
21 (PPO: rubber- Sm~ll-particle
22 Example modified polystyrene) FG-834 control EPDM rubber
23 XXVa 35:65 4.7 5.0
XXVb 50:50 5,2 4,8
XXVc 65:35 4,3 4,3
26 ______________________________ __________________ _______________
27
- 35 -
~ . . . _ _
~-45n I
(8~H 28~) .
~ 2
.,: .`
1 TABLE 5
. 2
3 I Avg.
;: Burning
4 Type of Time
ExamDle Polystyrene Flame Retardant~seconds) Rating
. 5 . ~ ,_
6 + `
: I C-4 FG-834 none drips Fails
7C-5 FG-834 triphenylphosphate 21 V-2
8 (3 phr)
: g C-6+FG-834 brominated diphenyl . 7.5 V-l
. ¦ . ether (12 phr) and
10 . I A.O. ~3 phr)
11I XXa Small-particle none drips Fails.
12 EPDM~modified
.. XXb Small.-particle triphenylphosphate 16 V-l
. 13 EPDM-modified (3 phr)
14 XXc Small-particle brominated diphenyl . 1.5 V-O
EPDM-modified ether (12 phr) and
: 15 A.O. (3 phr)
` 16 ~
: 17 ______~_______ _______ ________ __________________________________
` ` 18 ¦¦ + Control
19 1 . . .
.. .
:' Z~ . . ~
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; 22 ~` : ~3 I . . ~ :
24 .
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- 3.6 - :
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, . . _ . . ... __ ............ . . .
(8C11-2428) 11
'~ ' ' I ' . ,
~ 9~2
. 1 EXAMPLE XXI
2 EPDM-modified polystyrene was prepared as described
:: 3 in Example I from 100 g of Vistalon 6505 EPDM rubber and 900 g
4 1 of ~tyrene. The median rubber particle diameter in the product
was 1.8 microns.
:: 6 Three hundred twenty-five grams of the modified poly-
7 ~tyrene, 16$ g of PPO, 2.5 g of tridecyl phosphite, 35 g of
8 triphenyl pho~phate, 0.75 g of zinc sulfide, and 0.75 g of zinc
:. 9 oxide were mixed, extruded, and molded as described in Example I.
The properties of the molded product are compared in Table 6 .
. 11 with those of a similar compositlon prepared from Taflite 925
.~ 12 EPDM-modified polystyrene. It can be seen that the eomposition
.: 13 prepared from polystyrene containing small-particle EPDM
: 14 rubber is significantly superior in Izod impact strength, Gardner
.. 15 impact strengt~ and ductility to that made with polystyrene
:~. 16 containing large-particle EPDM rubber,
17 /
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1 ¦¦ EXAMPLE XXII
I ..
.,
2 Fifty parts of EPDM-modlfied polystyrene, prepared as
3 descrlbed in Example I, and with a mean rubber particle diameter
4 of 1.5 mlcrons,wereblended with 50 parts of PPO-having an in-
trinsic viscosity of 0.43 dl/g and 1.5 parts of polyethylene
6 ! and was extruded and molded as descrlbed in Example I. A second
l .
7 1 composition was prepared in th~ same way, with the addition of
8 3 parts of trip~enyl phosphate as a flame retardant. Other -
9 compositions were prepared in the same way with a 65:35 ratio
of PPO to EPDM-modified polystyrene. The molded bars were
11 tested for fla~mability in 1/16" sections according to thè pro-
12 cedure of UL 94, with the following results:
13 ! TABLE 7. -
14 - UL 94
PPO: Notched Avg.
Modif~ Izod Burning; Poly- TPP (ft.lbs./ HDT Time -
16 ~mple PolYstyrene ~y~ r~ in.~ (F) (~conds~ R~
17 ! XXlIa Sm~ particle 50:50 - 2.5 272 48.0 Fal ls
l EPDM-m~dlfied
:1~
XXIIb Small-particle 50:50 3 2.5 24513.3 Y-l
19 ¦ EPDM-modified
¦ XXIIc Small-partlcle 65:35 ^ 2.4 298 30.0 Fai lg
21 ¦ - EPDM-modified
XXIId Small-particle 65:35 3 2.5 255 7.9 V-l
22 EPDM-modi~ied
23 C-8~ FG-834 50:50 3 3.2 23425 6 Fa 18
24
~ 25
! I _____________________________ _____________________ ______________
26 + Control
27 1
! .
~ - 39 - ~
GE-~
(8CH~4283l ~ 99 2
: ',
.,
1 EXAMPLE XXIII
2 The procedure of Example I was followed, but with
3 1 lOO g of Royalene 302 (a terpolymer o~ ethylene, propylene,
¦ and dicyclopentadiene manufactured by Uniroyal Chemical) in
5 ¦I place of the Epcar 387. The median rubber particle diameter,
6 l¦ estimated as described in Example I, was 1.8 microns. The
7 l¦ polystyrene was blended, extruded, and molded with PP0 as
8 ¦¦ descrlbed in Example I. The molded test bars had notched Izod
9 l¦ impact strength of 3,0 ft.lbs/inch of notch~ A control composl~o n,
lO I extruded and molded at the same time, using FG-834 polystyrene,
~ had notched Izod impact strength of 3.5 ft.lbs/inch of notch.
12
13 1 EXAMPLE XXIV
14 1 EPDM~modified polystyrene was prepared as described
¦ in Example I, but w~th 9% rubber (100 g of Epcar 387 and 1011 g
16 ¦ of styrene) and wlth 0.03 g of lecithin added. The median
]7 1 par~cle diameter, determined as descri~ed in Example I, was
18 0.9 microns. The number average particle diameter, determlned
19 1 by means of a Coulter Counter with a 30 micron sample tube,
1 was 0.53 microns. The product was blended, extruded and molded
21 1I with PP0 as described in Example I; it had a notched Izod
22 l impact strength of 4,2 ft.lbstinch of notch~ compared to 4.8
23 1 ft.lbs/inch for a control sample extruded and molded at the
24 same time wlth FG-834 polystyrene.
/
26 /
27 ~! /
.,,.~, 11 ,
- 40 -
'.,.' , . . ,.-
.. ..... _ ..
- r
8CH-2428
Z
EPDM-modified polystyrenes were prepared according to
the procedure of Example I, except that varying amounts,
fxom 0.5 to 5 ml, of tert-dodecyl mercaptan were added to the
mi.xture~ either at the beginning of the reaction or just
prior to suspension in water, to modify the molecular weight
o~ the polymer. The polymerization temperature during the
first hour after suspension in aqueous solution was varied
between lO0 and 135C. The polymers were isolated, charac-
terized, and blended with PPO as described in Example I,
with the results shown in the following table:
TABLE 9
Median Polystyrene
Particle Intrinsic I~od Impact Strength
Size Viscosity of Composition with PPO
Example (microns) (dl/g) (ft. lbs./in of notch)
IIb 1.0 0.41 3.1
IIIb 1.0 0.44 3.4
IVb 1.2 0.56 4.1
Vb 1.1 0.62 4.5
VIb 1.0 0.63 4.0
VIIb l.l 0.73 4.4
VIIIb 1.2 0.86 4.1
IXb 1.0 0.91 4.0
Xb 1.1 l.01 4.4
_____________________________________________________________
The relationship between polystyrene intrinsic viscosity
and Izod impact strength shown in Table 9 is set forth in
~igure 3. It can be seen that although the median particle
diameter varied only between 1.0 and 1.2 microns, Izod
impact strength of 50:50 compositions with polyphenylene
ether resin increased sharply with increasing polystyrene
- 41 -
8CH--2428
lntrinsic viscosity, reached a maximum at a value of about
0.50 dl/g, and was essentially unaffected by further increase
in the polystyrene molecular weight.
The procedure of Example I was followed in three
separate runs. To one of the EPDM rubber-polystyrene reac- -
tion mixtures 20 g of KAYDOL TM were added; to another, 10 g
of KAYDOL; and no mineral oil was added to the third reaction
mixture. Each of the resulting modified polymers, as well
as Foster-Grant 834 polybutadiene-modified polystyrene were
blended with PPO, extruded, and molded as described in
Example I except that the PPO used had an intrinsic viscosity
of 0.43 dl/g and that phenyldidecycl phosphite was sub-
stituted for tridecyl phosphite. The results of testing
of the compositions are set forth in the following table: --
TABLE 10
Mineral Izod Impact Gardner Impact
Oil (ft.lbs./in.) (in.lbs.) HDT
Example (% by wt.) rm. temp. -40 C rm. temp. -40 C (F)
` IIC O 4.2 0.8 200 15 244
20IIIC 1 4.1 1.2 250 30 242
IVC 2 4.5 1.2 190 35 243
C-l* -- 3.2 1.5 175 40 239
___________ :
~ ~Control made from FG-834
. . .
~ - 42 -
, , .. . . - : : :
..
~ 8CH-2428
EXAMPLES IId-IXd
A series of EPDM-modified polystyrene compositions
having varying levels of Epcar 387 rubber were prepared by
the procedure described in Example I. Each of the polymers
was blended and extruded with PPO (I.V. = 0.45 dl/g) in the
proportion of 50 parts EPDM-polystyrene, 50 parts PPo, 3
parts tri-phenyl phosphate, 1.5 parts of polyethylene, 1
part of decyldiphenyl phosphite, d.l5 parts of zinc sulfide
and 0.15 parts of zinc oxide. All of the materials had
approximately the same heat deflection temperature and
tensile strength, and all had V-O flammability rating.
Impact properties are listed in the table below:
TABLE 11
Average
Particle Izod Impact Gardner
EPDM Rubber Diameter (ft.lbs./in. Impact
Example (% by wt.) (microns) of notch (in.lbs)
IId 0 --- 0.8 10
IIId 4 0.9 1.7 25
IVd 6 0.9 2.5 75
20Cd 8 0.9 3.1 200
VId 9 1.0 3.4 225
VIId 10 1.0 3.4 225
VIIId 12 1.0 4.6 250
IXd 15 1.1 5.3 400
:1
C-l * --- --- 3.4 175
_____________________________________________________________
*Control made from FG-834
It can be seen that when the EPDM rubber content of the
EPDM rubber-modified polystyrene compositions is below 8% by
weight, both the Izod and Gardner impact strengths are in-
30 ferior to those of the control composition made with FG-834.
';
~ - 43 -
~ 8CH-2428
Z
The Izod and Gardner impac~ stren~ths of the modified com-
position having a rubber content of 8% by weight are
approximately e~uivalent to those of the control composition
(L0~ lower in Izod impact strength, 10% higher in Gardner
impact strength) and the modified compositions having a
rubber content of at least 9% by weight have Izod and
Gardner impact strengths equal to or significantly better
than those of the control compositions.
EXAMPLES IIe ~ IVe
Three EPDM-modified polystyrenes were prepared by the
general method described in Example I, using the same amounts
of rubber, styrene, and catalyst. For Polymer IIe the mixture
was heated for five hours at 100C; then 8.0 g of tertbutyl
peroxide were added, and the polymer was drawn off and heated
in sealed bottles in an oven, first for 15 hours at 105C,
then for 2-1/2 hours at 125C, 1-1/2 hours at 135C, 1-1/2
hours at 145C, and finally, for 1-1/2 hours at 165C.
For Polymer IIIe the mixture was again heated for five
hours at 100C., 6.0 g of dibutyl peroxide were added, -~
followed by 4.0 g of polyvinyl alcohol and 1500 ml of water,
and the mixture was then heated for two hours at 120C, one
hour at 140C, and two hours at 155C. Polymer IVe was
prepared exactly as described in Example I except that 3
ml of dodecyl mercaptan were added just prior to suspension.
; The polymers were characterized and blended into PPO
as described in Example I. The results are summarized in
; the following table:
:,
44
, ,.
. -:- . -- . -- , .
: , : .- . ~ . ...
. . ..
8CH-2428
TABLE 12
Izod Impact
Poly- Strength of
Particle styrene Toluene 50:50 Comp.
Size I.V. Graft Insoluble Swell with PPO
Polymer (micron) (dl/g) Index (~ by wt) Index (ft.lbs/in)
IIe 1.1 0.60 1.8 0.7 18.6 1.1
IIIe 1.1 0.63 1.8 5.8 15.1 4.5
IVe 1.1 0.62 1.8 8.1 14.6 4.2
_____________________________________________________________
EXAMPLES Ve and VIe
Two polymers were prepared as described in Example
I, but with 8% rather than 10~ of rubber (100 g of Epcar
587 EPDM rubber and 1150 g of styrene). Polymer Ve was
prepared as described in Example I; for Polymer VIe the sus-
pending solution contained, instead of poly(vinyl alcohol)
and gelatin, 3.7 g of sodium phosphate, 4 g of calcium
chloride, 3.6 g of sodium 2-ethylhexyl sulfate and 1.1 g of
lime. The heating schedule was also changed: 2 hours at
120C, 1 hour at 140C, and 1-1/2 hours at 155C~ The
properties of the polymers were as follows~
TABLE -13
Izod Impact
Poly- Strength of
; Particle styrene Toluene 50:50 Comp.
Size I.V. Graft Insoluble Swell with PPO
Polymer (micron (d/g) Index (%by wt.) Index (ft.lbs/in)
Ve0.8 0.98 2.3 5.7 9.7 3.3
VIe0.8 0.97 2.1 0.1 19.5 1.1
________ ____________________________________________________ ~
,
~ - 45 -
.
~ 2 8CH-2428
EXAMPLES VIIe - XXIIIe
In examples IIe - Vie a comparision was made between EPDM-
modified polystyrenes which were very similar in particle
size, I.V., and graft index but which varied in gel content.
Several additional modified polymers containing 10~ EPDM
rubber were prepared following the procedure of Example I
but varying the temperature and other reaction conditions.
Impact strengths were determined as a percent of the value
obtained on a control made with FG-834, extruded and molded
at the same time. This was done to minimize the effects
of possible variations in extrusion and molding conditions
and of lot to lot variations in the PPO employed. The
results of the testing are set forth in the following table:
TABLE 14
Toluene Izod Impact Strength
Insoluble Swell of 50:50 Comp.with PPO
Polymer (% by wt.~ Index (~ of Control with FG-834
VIIe 0.5 17.0 24
VIIIe 0.6 29.0 24
IXe 0.7 18.6 27
20Xe 2.2 18.7 85
XIe 3.2 18.3 97
XIIe 4.7 15.5 100
XIIIe 5.5 15.8 92
XIVe 5.8 15.1 100
XVe 6.8 14.0 97
- XVIe 8.8 19.5 92
XVIIe 9.0 13.1 89
XVIIIe13.8 8.9 89
XIXe 15.7 11.4 88
30 XXe 23.6 11.0 92
XXIe 26.2 9.0 87
~ XXIIe 29.2 10.0 67
; XXIIIe30.4 8.0 65
~: --_______
- 46 -
8CH-2428
The data in Table 14 has been plotted on the graph of
Fig. 4. It can be seen that compositions having modified
polystyrene with a gel content greater than about 2~ by
weight, particularly those in the range of about 2 to
30% by weight, have good impact strength.
EXAMPLES IIf - VIIIf
EPDM-modified polystyrenes containing 10% EPDM rubber
were prepared as described in Example I, but using other
EPDM rubbers as well as Epcar 387. The other EPDM rubbers
were Nordel ~ 1320 and Nordel 2722 ~commercially available
from E.I. du Pont de Nemours & Co.); Epcar 346 and Epcar
587 (commercially available from B.F. Goodrich Chemical.);
Royalene ~ 521 (commercially available from Uniroyal
Chemical; and Vistalon ~ 6505 (commercially from Exxon
Chemical Co. ). Compositions with PPO ~ were extruded and
molded as described in Example I. In each case a control
composition was prepared at the same time, from the same
lot of PPO, but using Foster-Grant 834 polystyrene in place
of the EPDM-modified polystyrene.
Impact strengths of the compositions are listed in
the table below. To eliminate the effect of possible
variation in extrusion conditions or in lot to lot variations
of the PPO used, the results are expressed in each case as
the percent of the value obtained from the Foster-Grant
834 control sample.
.
,
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- 47 -
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-- 48 --
