CA1111992A - Compositions of a polyphenylene ether resin and alkenyl aromatic resins modified with epdm rubber - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Novel compositions are disclosed which include a polyphenylene ether resin and an alkenyl aromatic resin modified with an EPDM rubber comprised of particles having a median diameter less than about two microns. Also included within the scope of this invention are reinforced and flame-retardant compositions of said polyphenylene ether resin and said alkenyl aromatic resin modified with an EPDM rubber.

Description

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., ` .

- . . , . . -............... . -. .. .... :. ~ .. : ~ . - . : .

~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 --: -. - , - :- . . -- ............................ :, . :
:- , - ., . - - : , ~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 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.

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 ,, . . - .

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 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

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, .. ..

.,........... ~ , . :
.. . . .

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 ~. " - .
.

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 .

- . - .
- . . .: . . : .

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 8CH~2428 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.

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' ' . ~ . , ' . ' ,., ' ' '; : ' - ' - . ' ' '', ~ ' -~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~

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CIi-24 il ~L1~199Z
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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 , -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' 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!' ' ~ 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 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 ~

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.

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.

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, 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, 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.

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 ! ~

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:

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 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 .

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.

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 ~
: .

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.

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 ....

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~

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 ., . -.. .. ~. . . :
. . . . , .. ~ ~ .. .

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.

"

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 : 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 .--r . ~ :

: GE-450 (8C~2428) .
.. .

~ Z

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 / .

24 t . 25 /

,. 27 /
. - 32~-'~.
, . . . . . ~
:'~ . . .
:. . . : . - . . :

(8CI~ 2~,~
~ 9~2 ,. .

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 . .

.. ~4 r ~ 25 1 '` 26 1 .~ 27 ~ - 33 -.~.,., , . ~
~.`, ~1 ` `' , .:: :

~ GE-4 . (8CH-2428) ~ 9 9 2 ''' ` . . .

. 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 :

: 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

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:

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 ______________________________ __________________ _______________ ~ . . . _ _ ~-45n I
(8~H 28~) .
~ 2 .,: .`

. 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~ . . ~
` 21 . .
; 22 ~` : ~3 I . . ~ :
24 .
`25 .
` 26 . .: .
~` 27 .
- 3.6 - :
~, . ' ' , ~
, . . _ . . ... __ ............ . . .

(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, `.~ 18 / .
'~',, 19 / ' / .
21 / .
;.: 22 / . ~
23 ~ . :

. 25 /
. ~
26 / .

` 27 1 ~ 37 -:''.`' ~ I . ' :
',, ~ .. , _ _ _ ..... _ GE-4 ' ~ . .
(8CH-;~428) ¦ 3L~992 ~3~ .
O~ O
o ~i 3 ~-:. ~ ~ ~ o U~
. 5 ~ e~l , 6 u~ ' :
:: 7 .' 9 ~ ~ O I

~,.,j a~ '` l .
.. 11 ¦ ~ G . ~ O
. 12 ~D E~ ,~

3 ~ ~C~
.. ~ 15 . ~ -16 . .,~

;~ 3 . ~0 c~J ~I . :~

9 ~ I t~

~; ~ 21 23 . I ,~ .
;`'''`' ~. 24 . ~ ll C.? : -: 25 . ~ I ~
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. !. 26 .
`; 27 . :
` I - 38 - : .

'~428i ,11 .:
gZ ,, ~1 ., 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. -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 ~ 25 ! I _____________________________ _____________________ ______________ 26 + Control ! .
~ - 39 - ~

GE-~
(8CH~4283l ~ 99 2 : ', ., 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.

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.
/

27 ~! /
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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:

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 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: --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 . . .

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~ 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:

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.
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~ - 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:

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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~

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:

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 ~: --_______ 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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Claims (24)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An improved thermoplastic molding composition which comprises:
(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 modified with a rubbery interpolymer of a mixture of mono-olefins and a polyene, wherein the improvement comprises using a rubbery interpolymer comprised of particles having a median diameter less than about two microns.

2. The molding composition of Claim 1 wherein the alkenyl aromatic resin is modified with a rubbery inter-polymer of ethylene, an alpha-olefin, and a polyene.

3. The molding composition of Claim 2 wherein the alpha-olefin is propylene.

4. The molding composition of Claim 1 wherein said rubbery interpolymer comprises 10-90 mole percent of ethylene, 10-90 mole percent of an alpha-olefin having 3-16 carbon atoms, and 0.1-12 mole percent of a polyene that is a non-conjugated cyclic or open-chain diene having 5-20 carbon atoms.

5. The molding composition of Claim 4 wherein the alpha-olefin is propylene.
6. The molding composition of Claim 4 wherein the polyphenylene ether resin is selected from compounds of the formula

Claim 6 Cont'd 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 sub-stituent 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 the halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus.

7. The molding composition of Claim 4 wherein the alkenyl aromatic resin is prepared from a monomer selected from the group consisting of styrene, .alpha.-methylstyrene, bromostyrene, chlorostyrene, divinylbenzene, and vinyl-toluene.

8. The molding composition of Claim 1 wherein said composition includes a reinforcing amount of an inorganic reinforcing filler.

9. The molding composition of Claim 8 wherein said composition includes 10-80% by weight of fibrous glass fila-ments, based on the total weight of the composition.

10. The molding composition of Claim 1 wherein said composition includes a flame-retardant amount of a flame-retardant additive.

11. The molding composition of Claim 10 wherein said flame-retardant is a halogenated organic compound, a halo-genated organic compound is admixture with an antimony compound, elemental phosphorus, a phosphorus compound, compounds containing phosphorus-nitrogen bonds, or a mixture of two or more of the foregoing.
12. The molding composition of Claim 1 wherein the rubbery interpolymer is comprised of particles having a

Claim 12 Cont'd median diameter in the range of about 0.5 to 1.5 microns.

13. An improved thermoplastic molding composition which comprises:
(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 modified with a rubbery interpolymer which comprises 10-90 mole percent of ethylene, 10-90 mole percent of an alphaolefin having 3-10 carbon atoms, and 0.1-12 mole percent of a polyene that is a non-conjugated cyclic or open-chain diene having 5-10 carbon atoms, wherein the improvement comprises using a rubbery interpolymer com-prised of particles having a median diameter in the range of about 0.5 to 1.5 microns.

14. The molding composition of Claim 13 wherein said polyphenylene ether resin is poly(2,6-dimethyl-1,4-pheny-lene) ether.

15. The molding composition of Claim 13 wherein the alpha-olefin is propylene.

16. The molding composition of Claim 13 wherein said alkenyl aromatic resin is styrene and said rubbery inter-polymer is present between about 4% and about 25% by weight of styrene and rubbery interpolymer combined.

17. The molding composition of Claim 13 wherein said rubbery interpolymer comprises 10-90 mole percent of ethylene, 10-90 mole percent of propylene, and 0.1-12 mole percent of 5-ethylidene-2-norbornene.

18. The molding composition of Claim 13 wherein said rubbery interpolymer comprises 10-90 mole percent of ethylene, 10-90 mole percent of propylene, and 0.1-12 mole percent of 1,4-hexadiene.

19. The molding composition of Claim 13 wherein said rubbery interpolymer comprises 10-90 mole percent of ethylene, 10-90 mole percent of propylene, and 0.1-12 mole percent of dicyclopentadiene.

20. The composition of Claim 1, 6 and 13 wherein said modified alkenylaromatic resin has an intrinsic viscosity of at least about 0.50 dl/g.

21. The composition of claim 1, 6 or 13 wherein said modified alkenyl aromatic resin contains a small quantity of a mineral oil.

22. The composition of Claim 1, 6 or 13 wherein said modified alkenyl aromatic resin contains at least about 8% by weight of rubbery inter polymer.

23. The composition of Claim 1, 6 or 13 wherein said modified alkenyl aromatic resin contains at least about 2% of a toluene insoluble gel.

24. The composition of claim 1, 6 or 13 wherein said rubbery interpolymer has a propylene content of not greater than about 45% by weight.