EP0491884A1

EP0491884A1 - Polyphenylene ether-polyarylene sulfide compositions

Info

Publication number: EP0491884A1
Application number: EP91907370A
Authority: EP
Inventors: Timothy Mark Sivavec; Sharon Mccormick Fukuyama; Andrew James Caruson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1990-07-16
Filing date: 1991-03-28
Publication date: 1992-07-01
Also published as: WO1992001749A1; JPH05500535A

Abstract

On prépare des compositions compatibles contenant un copolymère, en faisant réagir un éther de polyphénylène recouvert de salicylate, préparé de préférence par la réaction d'un éther de polyphénylène avec un ester de salicylate phénylique anhydride trimellitique, avec un sulfure de polyarylène contenant des groupes amine, de préférence préparé par la réaction d'un sulfure de polyarylène avec un bisulfure contenant des groupes amine. Ces compositions peuvent également contenir des modificateurs d'impact compatibles avec l'éther de polyphénylène.Compatible compositions containing a copolymer are prepared by reacting a polyphenylene ether coated with salicylate, preferably prepared by the reaction of a polyphenylene ether with a trimellitic anhydride phenyl salicylate ester, with a polyarylene sulfide containing amine groups. , preferably prepared by reacting a polyarylene sulfide with a bisulfide containing amine groups. These compositions may also contain impact modifiers compatible with polyphenylene ether.

Description

POLYPHENYLENE ETHER-POLYARYLENE SULFIDE COMPOSITIONS

This invention relates to the preparation of compatible polyarylene sulfide-polyphenylene ether compositions, and more particularly to the preparation of copolymer-containing compositions.

The polyphenylene ethers are a widely used class of thermoplastic engineering resins characterized by excellent hydrolytic stability, dimensional stability, toughness, heat resistance and dielectric properties. However, they are_. deficient in certain other properties such as solvent resistance.

For their part, polyarylene sulfides are crystalline engineering thermoplastics with high crystalline melting temperatures, typically on the order of 285^*C, and are characterized by low flammability, high modulus and excellent resistance to aggressive chemicals and solvents. However, their glass transition temperatures are very low, typically as low as 85'C; as a consequence, heat distortion temperatures are low in the absence of reinforcement with fillers such as glass fiber. In addition, polyarylene sulfides are very brittle, as evidenced by a tensile elongation for polyphenylene sulfide usually no greater than about 2.5% and frequently below 1%.

It might be expected that polyarylene sulfide- polyphenylene ether blends could be prepared which would have such properties as high solvent resistance, high heat distortion temperature, good ductility and resistance to flammability. However, blends of this type are incompatible and undergo phase separation and delamination, as a result of little or no phase interaction between the two resin phases. Molded parts made from such blends are typically characterized by low tensile and impact strength.

It has been discovered that polyarylene sulfide- polyphenylene ether blends can be compatibilized by incorporating therein a copolymer of the two resins, prepared from polymers in which various functional groups have been incorporated. This method of compatibilization is disclosed, for example, in Example 1 of EP-A-0341422, which is directed to a composition prepared from poly(2, 6-dimethyl-l,4- phenylene ether) , a polyphenylene sulfide and the product obtained by melt blending the aforesaid polyphenylene ether with trimellitic anhydride acid chloride. Said composition is characterized by a substantial increase in tensile elongation, in comparison with a similar non-compatibilized PPS-polyph^'enylene ether blend. Under the heading "B. Polyarylene sulfide", it is said that the polyarylene sulfides used in the compositions of that application are prepared from a polyhaloaromatic compound, an alkali metal sulfide, an organic amide and, optionally, an alkali metal carboxylate.

The present invention provides a method for preparing a composition comprising polyphenylene ether- polyarylene sulfide copolymer molecules which comprises melt blending a polyarylene sulfide containing amine groups with a capped polyphenylene ether prepared by the reaction of a polyphenylene ether with at least one trimellitic anhydride salicylate ester of the formula

wherein R¹ is a Cι-6 alkyl or a Cβ-io aromatic hydrocarbon The polyarylene sulfides employed in the present invention are known polymers containing arylene groups separated by sulfur atoms . They include polyphenylene sulfides (hereinafter "PPS") and substituted polyphenylene sulfides .

By reason of its availability and relatively low cost, PPS is often preferred. PPS is typically prepared by the reaction of p-dichlorobenzene with sodium sulfide, optionally with the use of a minor proportion of 1,3,5- trichlorobenzene as a branching agent. Reference is made, for example, to U.S. Patent 4,794,163, for a disclosure of typical reagents and conditions employed in polyarylene sulfide preparation.

It is often impracticable to determine the molecular weight of a polyarylene sulfide, by reason of its insolubility in essentially all solvents used for molecular weight determination. Indirect characterization of relative molecular weight by melt flow characteristics is commonly employed. The melt flow characteristics of the polyarylene sulfides used according to this invention are not critical; values in the range of 20-1000 g./lO min. (315'C, 5 kg. load) are typical.

It is known that polyarylene sulfides can be "cured" by heating in contact with an oxygen-containing gas (usually air) at temperatures above about 200^*C, resulting in a substantial decrease in melt flow and, apparently, a concomitant increase in molecular weight. While the exact nature of the curing reaction is not known, it appears to involve branching and/or chain extension, which probably occurs thermally or by oxidation of some type. It is frequently preferred to employ cured polyarylene sulfides in the present invention. Curing may be performed either before or after amine functionalization; it is often especially preferred to cure at both times, in order to counteract the decrease in molecular weight as a result of polymer chain scission during the reaction with an amine group-containing disulfide. Curing is typically conducted in the solid or liquid state at temperatures in the range of 225-350"C for time periods of 2-6 hours. For the purposes of the invention, it is necessary that the polyarylene sulfide contain amine groups, preferably primary amine groups. They may be provided in a number of ways .

One of these, disclosed, for example, in U.S. Patent 4,769,424, comprises the reaction of a dihalodiaryl sulfide with an alkali metal sulfide to form a halogen- terminated polyarylene sulfide, which then undergoes further reaction with an aminothiophenol with elimination of hydrogen halide to form a polyarylene sulfide having the required amine substituents on the end groups . In another method, the polyarylene sulfide is prepared by the reaction of an alkali metal sulfide with a mixture of dichloroaromatic compounds and/or monochloroaromatic compounds (used as chain termination agents) , including at least one such compound which contains the required amine group.

A third method, disclosed and claimed in copending published International Application WO 91/00310 and generally preferred, is the reaction of a polyarylene sulfide with a disulfide containing amine groups, typically at temperatures in the range of about 225-375"C, in the melt or in solution in a suitable high boiling solvent such as 1- chloronaphthalene.

The preparation of a ine-functionalized polyarylene sulfides by the above-described third method is illustrated by the following examples. All percentages are by weight. PREPARATION OF REACTIVELY-CAPPED PPS

PREPARATION I

An intimate mixture of 5 grams of PPS having a melt flow of 71 g./lO min. at 300^*C and 5 kg. load in fine powder form and 250 mg. of bis (4-aminophenyl) disulfide was purged with nitrogen, heated at 350"C for 6 minutes with mechanical stirring and cooled. The product was dissolved in 15 ml. of 1-chloronaphthalene at 230'C, cooled to room temperature and extracted with chloroform in a Soxhlet extractor, leaving as the residue 4.81 grams (96% of theoretical) of a solid which was cured by heating in air for 4-1/2 hours at 260^*C. It was shown by Fourier transform infrared spectroscopy and elemental analysis to be the desired aminophenyl-terminated PPS, containing a proportion of amino functionality corresponding to 71% of the bis (4-aminophenyl) disulfide employed.

PREPARATION TT

The procedure of Preparation I was repeated, except that 375 mg. of bis (4-aminophenyl) disulfide was employed. A similar product was obtained.

PREPARATION III

Three reactively capped PPS compositions were prepared from the PPS employed in Preparation I, using 1.52%, 0.5% and 0.1%, respectively, of bis (4-aminophenyl) disulfide. Preparation was by melt blending in a counterrotating twin screw extruder at 400 rpm., at temperatures in the range of 135-302^*C. The compositions prepared from 0.5% and 0.1% disulfide were easily stranded, affording somewhat brittle, wire-like strands. The composition prepared from 1.52% disulfide was stranded with difficulty.

Each composition was cured by heating at 260^*C in a forced air oven. A pronounced decrease in melt flow was noted with cure times greater than 1 hour; optimum melt flow conditions were obtained at curing times of 4-6 hours.

Samples comprising about 100 mg. of each uncured and cured composition were placed between two pieces of polytetrafluoroethylene-coated foil held between two stainless steel plates, placed in a Carver press preheated to 300-310"C, equilibrated for 1 minute and pressed at 1050 kg./cm.². The pressure was released and the polymer and foil sheets were immediately quenched in a water bath to prevent crystallization of the PPS chains, after which they were subjected to quantitative infrared analysis which showed, in each instance, the presence of amine groups. It is thus apparent that the amine functionality was not lost upon curing, although the proportion thereof decreased slightly. It is often found that commercially available polyarylene sulfides prepared by conventional methods contain a measurable proportion of amine groups even if one of the above-described methods of preparation is not employed. This is probably a result of incorporation in the molecule of moieties derived from nitrogen-containing solvents such as N- methy1-2-pyrrolidone.

The precise proportion of amine groups which must be present on the polyarylene sulfide can readily be determined by simple experimentation. All that is required is the preparation and analysis of a reaction product with a polyphenylene ether containing amine-reactive (e.g., epoxy or carboxy) groups . If a substantial proportion of copolymer formation is detected, it may be assumed that the required amine groups were present in the necessary proportion on the polyarylene sulfide. In general, some degree of copolymer formation in accordance with the invention is observed if the nitrogen content of the polyarylene sulfide is above about 800 ppm., even if no detectable proportion of amino nitrogen is present. The reasons for this are not fully understood. Preferable nitrogen proportions are in the range of about 1200-3000 ppm., since a favorable tendency toward copolymer formation is often observed in that range.

The other reactant employed in the method of this invention is chosen from a specific class of capped polyphenylene ethers . The polyphenylene ethers from which they are prepared are a well known class of polymers widely used in industry, especially as engineering plastics in applications requiring toughness and heat resistance. Since their discovery, they have given rise to numerous variations and modifications all of which are applicable to the present invention, including but not limited to those described hereinafter.

The polyphenylene ethers comprise a plurality of structural units having the formula

In each of said units independently, each Q¹ is independently halogen, primary or secondary lower alkyl (i.e., alkyl containing up to 7 carbon atoms) , phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q² is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q¹. Examples of suitable primary lower alkyl groups are methyl, ethyl, n-propyl, n- butyl, isobutyl, n-amyl, isoamyl, 2-methylbutyl, n-hexyl, 2,3-dimethylbutyl, 2-, 3- or 4-methylpentyl and the corresponding heptyl groups . Examples of secondary lower alkyl groups are isopropyl, sec-butyl and 3-pentyl.

Preferably, any alkyl radicals are straight chain rather than branched. Most often, each Q¹ is alkyl or phenyl, especially Cι-₄ alkyl, and each Q² is hydrogen. Suitable polyphenylene ethers are disclosed in a large number of patents . Both homopolymer and copolymer polyphenylene ethers are included. Suitable homopolymers are those containing, for example, 2, 6-dimethy1-1, 4-phenylene ether units. Suitable copolymers include random copolymers containing such units in combination with (for example) 2,3, 6-trimethyl-l, 4- phenylene ether units. Many suitable random copolymers, as well as homopolymers, are disclosed in the patent literature.

Also included are polyphenylene ethers containing moieties which modify properties such as molecular weight, melt viscosity and/or impact strength. Such polymers are described in the patent literature and may be prepared by grafting onto the polyphenylene ether in known manner such vinyl monomers as acrylonitrile and vinylaromatic compounds (e.g., styrene) , or such polymers as polystyrenes and elastomers . The product typically contains both grafted and ungrafted moieties . Other suitable polymers are the coupled polyphenylene ethers in which the coupling agent is reacted in known manner with the hydroxy groups of two polyphenylene ether chains to produce a higher molecular weight polymer containing the reaction product of the hydroxy groups and the coupling agent, provided substantial proportions of free hydroxy groups remain present . Illustrative coupling agents are low molecular weight polycarbonates, quinones, heterocycles and formals .

The polyphenylene ether generally has a number average molecular weight within the range of 3,000-40,000 and a weight average molecular weight within the range of 20,000-80,000, as determined by gel permeation chromatography. Its intrinsic viscosity is most often in the range of 0.35-0.6 dl./g., as measured in chloroform at 25"C. The polyphenylene ethers are typically prepared by the oxidative coupling of at least one corresponding monohydroxyaromatic compound. Particularly useful and readily available monohydroxyaromatic compounds are 2,6- xylenol (wherein each Q¹ is methyl and each Q² is hydrogen) , whereupon the polymer may be characterized as a poly(2, 6- dimethyl-1, 4-phenylene ether), and 2, 3, 6-trimethylphenol (wherein each Q¹ and one Q² is methyl and the other Q² is hydrogen) .

A variety of catalyst systems are known for the preparation of polyphenylene ethers by oxidative coupling. There is no particular limitation as to catalyst choice and any of the known catalysts can be used. For the most part, they contain at least one heavy metal compound such as a copper, manganese or cobalt compound, usually in combination with various other materials.

A first class of preferred catalyst systems consists of those containing a copper compound. Such catalysts are disclosed, for example, in U.S. Patents 3,306,874, 3,306,875, 3,914,266 and 4,028,341. They are usually combinations of cuprous or cupric ions, halide (i.e., chloride, bromide or iodide) ions and at least one amine. Catalyst systems containing manganese compounds constitute a second preferred class. They are generally alkaline systems in which divalent manganese is combined with such anions as halide, alkoxide or phenoxide . Most often, the manganese is present as a complex with one or more complexing and/or chelating agents such as dialkylamines, alkanola ines, alkylenediamines, o-hydroxyaromatic aldehydes, o-hydroxyazo compounds, ω-hydroxyoximes (monomeric and polymeric), o-hydroxyaryl oximes and β-diketones . Also useful are known cobalt-containing catalyst systems. Suitable manganese and cobalt-containing catalyst systems for polyphenylene ether preparation are known in the art by reason of disclosure in numerous patents and publications. Particularly useful polyphenylene ethers for the purposes of this invention are those which comprise molecules having at least one of the end groups of the formulas

wherein Q¹ and ² are as previously defined; each R² is independently hydrogen or alkyl, with the proviso that the total number of carbon atoms in both R² radicals is 6 or less; and each R³ is independently hydrogen or a C -ζ primary alkyl radical. Preferably, each R² is hydrogen and each R³ is alkyl, especially methyl or n-butyl.

Polymers containing the aminoalkyl-substituted end ' groups of formula III may be obtained by incorporating an appropriate primary or secondary monoamine as one of the constituents of the oxidative coupling reaction mixture, especially when a copper- or manganese-containing catalyst is used. Such amines, especially the dialkylamines and preferably di-n-butylamine and dimethylamine, frequently become chemically bound to the polyphenylene ether, most often by replacing one of the α-hydrogen atoms on one or more

Q¹ radicals. The principal site of reaction is the Q¹ radical adjacent to the hydroxy groups on the terminal unit of the polymer chain. During further processing and/or blending,the aminoalkyl-substituted end groups may undergo various reactions, probably involving a quinone methide-type intermediate of the formula

with numerous beneficial effects often including an increase in impact strength and compatibilization with other blend components. Reference is made to U.S. Patents 4,054,553, 4,092,294, 4,477,649, 4,477,651 and 4,517,341, the disclosures of which are incorporated by reference herein.

Polymers with 4-hydroxybiphenyl end groups of formula IV are typically obtained from reaction mixtures in which a by-product diphenoquinone of the formula

is present, especially in a copper halide-secondary or tertiary amine system. In this regard, the disclosure of U.S. Patent 4,477,649 is again pertinent as are those of U.S, 4,234,706 and 4,482,697, which are also incorporated by reference herein. In mixtures of this type, the diphenoquinone is ultimately incorporated into the polymer in substantial proportions, largely as an end group.

In many polyphenylene ethers obtained under the above-described conditions, a substantial proportion of the polymer molecules, typically constituting as much as about 90% by weight of the polymer, contain end groups having one or frequently both of formulas III and IV. It should be understood, however, that other end groups may be present and that the invention in its broadest sense may not be dependent on the molecular structures of the polyphenylene ether end groups .

It will be apparent to those skilled in the art from the foregoing that the polyphenylene ethers contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features .

The capped polyphenylene ether used in the method of this invention is prepared by the reaction of the above- described polyphenylene ether with at least one trimellitic anhydride salicylate ester of formula I. In that formula, R¹ may be Cι-6 alkyl such as methyl, ethyl, 1-propyl, 2-propyl,

1-butyl, 2-butyl, 1-hexyl or 1- (2-methylpentyl) . The preferred alkyl radicals contain 1-3 carbon atoms, with methyl being most preferred. The R¹ value is more often a C_δ-io aromatic hydrocarbon radical such as phenyl, tolyl, xylyl, 1-naphthyl or 2-naphthyl, with phenyl being preferred. Thus, the most preferred trimellitic anhydride ester is the 4- (phenyl salicylate) or 4-(o-carbophenoxyphenyl) ester. Trimellitic anhydride salicylate esters useful for capping may be prepared by conventional methods. A particularly convenient method is the reaction of TAAC with an ester of salicylic acid, most often phenyl salicylate. The reaction between the polyphenylene ether and the trimellitic anhydride ester may be conducted in solution or in the melt. Melt reactions are usually preferred; they may be performed in conventional melt blending apparatus of both the batch and continuous type. They are often preferably conducted continuously in an extruder, by reason of the excellent properties of extruded materials and the availability of extruders in commercial polymer processing facilities. Typical conditions include temperatures in the range of 225-350"C, preferably 275-325'C. The proportion of trimellitic anhydride salicylate ester employed is not critical and will depend on the degree of dicarboxylate capping desired. It is most often about 3-5% but may be as high as about 10% by weight based on polyphenylene ether.

When melt blending is employed in the preparation of the capped polyphenylene ether, it is essential that it be conducted with application of vacuum. In general, blending processes involving pressures below about 20 torr for at least a portion of the process are desirable. Extrusion processes of this type may be conducted by means of vacuum venting, whereby a vacuum is drawn on at least one vent in the extruder.

The reaction between the polyphenylene ether and the trimellitic anhydride salicylate ester may be facilitated if the polyphenylene ether has also been melt processed under vacuum prior to formation of the blend with said ester. This melt processing operation may also be conveniently effected via extrusion with vacuum venting.

In addition, the properties of polyphenylene ether- polyamide compositions prepared from the dicarboxylate-capped polyphenylene ethers of the invention may be improved by repeated extrusion of the capped polyphenylene ether. Optimum conditions are often provided if the capped polyphenylene ether is again melt processed (e.g., reextruded) at least once, also under vacuum.

The preparation of the dicarboxylate-capped polyphenylene ethers is illustrated by the following examples. All parts are by weight. The polyphenylene ether employed was a commercially available poly(2, 6-dimethyl-l,4- phenylene ether) having an intrinsic viscosity in chloroform at 25^*C of 0.42 dl./g.

PREPARATION OF DICARBOXYLATE-CAPPED POLYPHENYLENE ETHER

PREPARATIONS TV TO X

Various samples of polyphenylene ether were dry blended in a Henschel mill with various proportions of trimellitic anhydride 4- (phenyl salicylate) ester, until the blends were homogeneous. The blends were then extruded on a twin-screw extruder at temperatures in the range of 180-300^*C,' with vacuum venting to a pressure of 20 torr or less. The extrudates were quenched in water, pelletized, dissolved in toluene and precipitated by the addition of methanol or a 2:1 (by volume) mixture of acetone and acetonitrile, followed by filtration and drying in a vacuum oven at 80^*C.

Three samples of polyphenylene ether were employed. Sample 1 was subjected to no treatment following precipitatio and.drying, sample 2 was extruded once with vacuum venting, and sample 3 was extruded twice with vacuum venting.

The extruded reaction products were analyzed for., hydroxy group content, dicarboxy functionalization and salicylate capping by Fourier transform infrared spectroscopy. The results are given in Table I, in comparison with a control prepared from a polyphenylene ether sample which had been precipitated without vacuum venting.

'Based on polyphenylene ether.

Copolymer formation according to the present invention is believed to be the result of reaction between the dicarboxylate end groups of the polyphenylene ether and amine groups in the polyarylene sulfide, forming imide linkages.

To prepare the copolymer compositions, the dicarboxylate-capped polyphenylene ether and polyarylene sulfide are heated together in solution or, preferably, in the melt. Here, as in the operations previously described, melt processing under vacuum is especially preferred and extrusion with vacuum venting is most preferred. The reaction temperature is typically within the range of about 100-350'C.

The proportions of functionalized polyphenylene ether and polyarylene sulfide are not critical and may be adjusted over a wide range to yield copolymer compositions having the desired properties. The polyphenylene ether- polyarylene sulfide compositions, however, generally contain about 5-75% by weight polyphenylene ether and about 25-95% polyarylene sulfide.

In general, the copolymer compositions comprise only partially copolymer, with the balance being a polyphenylene ether-polyarylene sulfide blend. It is also within the scope of the invention to incorporate in the composition uncapped polyphenylene ether and/or non-amine- functionalized polyarylene sulfide, said uncapped and/or unfunctionalized polymers frequently comprising up to about 50% by weight of total polyphenylene ether and polyarylene sulfide. Optimum properties are usually obtained when no uncapped polyphenylene ether is separately added; the opposite may be true, however, in regard to unfunctionalized polyarylene sulfide.

The polyphenylene ether-polyarylene sulfide compositions may also contain ingredients other than the copolymer, polyphenylene ether and polyarylene sulfide. A particularly useful other ingredient in many instances is at least one elastomeric impact modifier which is compatible with the polyphenylene ether. It is generally present in the amount of about 5-25% by weight of resinous components. Impact modifiers for polyphenylene ether compositions are well known in the art. They are typically derived from one or more monomers selected from the group consisting of olefins, vinyl aromatic monomers, acrylic and alkylacrylic acids and their ester derivatives as well as conjugated dienes . Especially preferred impact modifiers are the rubbery high-molecular weight materials including natural and synthetic polymeric materials showing elasticity at room temperature. They include both homopolymers and copolymers, including random, block, radial block, graft and core-shell copolymers as well as combinations thereof.

Polyolefins or olefin-based copolymers employable in the invention include poly(1-butene) , poly(4-methyl-l- pentene) , propylene-ethylene copolymers and the like. Additional olefin copolymers include copolymers of one or more α-olefins with copolymerizable monomers including, for example, acrylic acids and alkylacrylic acids as well as the ester derivatives thereof including, for example, ethylacrylic acid, ethyl acrylate, ethacrylic acid, methyl methacrylate and the like. Also suitable are the ionomer resins, which may be wholly or partially neutralized with metal ions .

A particularly useful class of impact modifiers are those derived from the vinyl aromatic monomers . • These include, for example, modified and unmodified polystyrenes, ABS type graft copolymers, AB and ABA type block and radial block copolymers and vinyl aromatic conjugated diene core- shell graft copolymers . Modified and unmodified polystyrenes include homopolystyrenes and rubber modified polystyrenes, such as butadiene rubber-modified polystyrene (otherwise referred to as high impact polystyrene or HIPS) . Additional useful polystyrenes include copolymers of styrene and various monomers, including, for example, poly (styrene-acrylonitrile) (SAN) , styrene-butadiene copolymers as well as the modified alpha- and para-substituted styrenes and any of the styrene resins disclosed in U.S. Patent 3,383,435, herein incorporated by reference. ABS types of graft copolymers are typified as comprising a rubbery polymeric backbone derived from a conjugated diene alone or in combination with a monomer copolymerizable therewith having grafted thereon at least one monomer, and preferably two, selected from the group consisting of monoalkenylarene monomers and substituted derivatives thereof as well as acrylic monomers such as acrylonitriles and acrylic and alkylacrylic acids and their esters.

An especially preferred subclass of vinyl aromatic monomer-derived resins is the block copolymers comprising monoalkenyl arene (usually styrene) blocks and conjugated diene (e.g., butadiene or isoprene) blocks and represented as AB and ABA block copolymers . The conjugated diene blocks may be selectively hydrogenated.

Suitable AB type block copolymers are disclosed in, for example, U.S. Patents 3,078,254; 3,402,159; 3,297,793; 3,265,765 and 3,594,452 and UK Patent 1,264,741, all incorporated herein by reference. Examples of typical species of AB block copolymers are polystyrene-polybutadiene (SBR) , polystyrene-polyisoprene and poly(alpha- methylstyrene)-polybutadiene. Such AB block copolymers are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE.

Additionally, ABA triblock copolymers and processes for their production as well as hydrogenation, if desired, are disclosed in U.S. Patents 3,149,182; 3,231,635; 3,462,162; 3,287,333; 3,595,942; 3,694,523 and 3,842,029, all incorporated herein by reference.

Examples of triblock copolymers include polystyrene-polybutadiene-polystyrene (SBS) , polystyrene- polyisoprene-polystyrene (SIS), pol (α-methylstyrene) - polybutadiene-poly- (α-methylstyrene) and poly(CC— methylstyrene) -polyisoprene-poly- (OC—^meth lstyrene) .

Particularly preferred triblock copolymers are available commercially as CARIFLEX®, KRATON D® and KRATON G® from Shell.

Another class of impact modifiers is derived from conjugated dienes . While many copolymers containing conjugated dienes have been discussed above, additional conjugated diene modifier resins include, for example, homopolymers and copolymers of one or more conjugated dienes including, for example, polybutadiene, butadiene-styrene copolymers, butadiene-glycidyl methacrylate copolymers, isoprene-isobutylene copolymers, chlorobutadiene polymers, butadiene-acrylonitrile copolymers, polyisoprene, and the like. Ethylene-propylene-diene monomer rubbers may also be used. These EPDM's are typified as comprising predominantly ethylene units, a moderate amount of propylene units and up to about 20 mole percent of non-conjugated diene monomer units. Many such EPDM's and processes for the production thereof are disclosed in U.S. Patents 2,933,480; 3,000,866; 3,407,158; 3,093,621 and 3,379,701, incorporated herein by reference . Other suitable impact modifiers are the core-shell type graft copolymers. In general, these have a predominantly conjugated diene rubbery core or a predominantly cross-linked acrylate rubbery core and one or more shells polymerized thereon and derived from monoalkenylarene and/or acrylic monomers alone or, preferably, in combination with other vinyl monomers. Such core-shell copolymers are widely available commercially, for example, from Rohm and Haas Company under the trade names KM- 611, KM-653 and KM-330, and are described in U.S. Patents 3,808,180; 4,034,013; 4,096,202; 4,180,494 and 4,292,233.

Also useful are the core-shell copolymers wherein an interpenetrating network of the resins employed characterizes the interface between the core and shell. Especially preferred in this regard are the ASA type copolymers available from General Electric Company and sold as GELOY™ resin and described in U.S. Patent 3,944,631. In addition, there may be employed the above- described polymers and copolymers having copolymerized therewith or grafted thereon monomers having functional groups and/or polar or active groups. Finally, other suitable impact modifiers include Thiokol rubber, polysulfide rubber, polyurethane rubber, polyether rubber (e.g., polypropylene oxide) , epichlorohydrin rubber, ethylene- propylene rubber, thermoplastic polyester elastomers and thermoplastic etherester elastomers.

The preferred impact modifiers are block (typically diblock, triblock or radial teleblock) copolymers of alkenylaromatic compounds and olefins or dienes . Most often, at least one block is derived from styrene and at least one other block from at least one of butadiene, isoprene, ethylene and butylene. Especially preferred are the triblock copolymers with polystyrene end blocks and olefin- or diene- derived midblocks . When one of the blocks is derived from one or more dienes, it is frequently advantageous to reduce - 20 -

the aliphatic unsaturation therein by selective hydrogenation. The weight average molecular weights of the impact modifiers are typically in e range of about 50,000-300,000. Block copolymers of this type are commercially available from Shell Chemical Company under the trademark KRATON, and include KRATON D1101, G1650, G1651, G1652, G1657 and G1702.

Other conventional ingredients which may be present in the copolymer-containing compositions include fillers, flame retardants, colorants, stabilizers, antistatic agents, mold release agents and the like, used in conventional amounts. The presence of other resinous components is also contemplated.

The invention is illustrated by the following examples. All parts and percentages are by weight. The polyphenylene ether employed was a poly(2, 6-dimethyl-l, 4- phenylene ether) having an intrinsic viscosity of 0.41 dl/g. in chloroform at 25^*C.

Examples 1-5

Dry blends of capped polyphenylene ethers similar to those obtained in Preparations IV to X, the amine- functionlized PPS of Preparation II and a commercially available triblock copolymer with polystyrene endblocks having weight average molecular weights of 29,000 and hydrogenated butadiene midblock having a weight average molecular weight of 116,000 were prepared and extruded on a twin-screw extruder at temperatures from 130-280"C, with vacuum venting. The extrudates were quenched in water, peiletized and molded into test specimens which were tested for tensile properties (ASTM method D638) , flexural properties (ASTM method D790) and heat distortion temperature at 1.8 MPa. (ASTM method D648) . The results are given in Table II, in comparison with a control employing uncapped vacuum-vented polyphenylene ether .

The improvement in tensile elongation of the compositions of this invention, in comparison with the control, is apparent. In addition, improvements of varying degree are seen in tensile strength, flexural strength and flexural modulus .

Examples 6-7

Solutions were prepared from 50 grams of various capped polyphenylene ethers similar to those obtained in Preparations IV to X and 50 grams of the product of Preparation II in 133 ml. of 1-chloronaphthalene. Said solutions were heated at 250"C for 12 hours, after which the polymers were precipitated by pouring into acetone in a blender, slurried repeatedly in acetone and extracted in a Soxhlet extractor with acetone for 24 hours to remove traces of 1-chloronaphthalene. The resulting solids were weighed and extracted with chloroform for 3 days in a Soxhlet extractor to remove uncopolymerized polyphenylene ether.

From the weight of the extracts, the amount of copolymerized polyphenylene ether was calculated. The results are given in Table III.

TAB E TTT

Example 6 7

Polyphenylene ether: % capping agent 8 6 Copolymerized polyphenylene ether 75 25.2

Claims

What is claimed is :

1. A method for preparing a composition comprising polyphenylene ether-polyarylene sulfide copolymer molecules which comprises melt blending a composition comprising a polyarylene sulfide containing amine groups and a capped polyphenylene ether prepared by the reaction of a polyphenylene ether with at least one trimellitic anhydride salicylate ester of the formula

wherein R¹ is a C -_ alkyl or a Cβ-io aromatic hydrocarbon radical.

2. A method according to claim 1 wherein the polyphenylene ether is a poly (2, 6-dimethyl-l, 4-phenylene ether) .

3. A method according to claim 1 or 2 wherein the polyarylene sulfide is a polyphenylene sulfide.

4. A method according to any preceding claim 2 wherein the polyarylene sulfide containing amine groups is prepared by the reaction of a polyarylene sulfide with a disulfide containing amine groups.

5. A method according to claim 4 wherein the disulfide is bis (4-aminophenyl) disulfide.

6. A method according to any preceding claim wherein R¹ is phenyl.

7. A method according to any preceding claim wherein the nitrogen content of the polyarylene sulfide is in the range of 1200-3000 ppm.

8. A method according to any preceding claim wherein the proportion of trimellitic anhydride phenyl salicylate ester employed in capping the polyphenylene ether is up to about 10% by weight based on polyphenylene ether.

9. A method according to any preceding claim wherein said composition also contains at least one elastomeric polyphenylene ether-compatible impact modifier.

10. A method according to any preceding claim wherein the capped polyphenylene ether and the polyarylene sulfide containing amine groups are present in said composition in the amounts of 5-75% and 25-95% by weight, respectively.

11. A composition prepared by the method of claim

12. A composition prepared by the method of claim

2.

13. A composition prepared by the method of claim

3.

14. A composition prepared by the method of claim

15. A composition prepared by the method of claim

5.

16. A composition prepared by the method of claim

17. A composition prepared by the method of claim

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