AU613376B2 - Impact modified polyester compositions with improved heat resistance - Google Patents

Description

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AU-AI-17925/88 WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau 0

PCT

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 88/ 07065 C08L 67/02, 51/06 Al (43) International Publication Date: 22 September 1988 (22.09.88) (21) International Application Number: PCT/US88/00677 (81) Designated States: AU, BR, DE (European patent), FR (European patent), GB (European patent), IT (Euro- (22) International Filing Date: 9 March 1988 (09.03.88) pean patent), JP, NL (European patent).

(31) Priority Application Number: 027,968 Published With international search report.

(32) Priority Date: 19 March 1987 (19.03.87) Before the expiration of the time limit for amending the claims and to be republished in the event of the receipt (33) Priority Country: US of amendments.

(71) Applicant: GENERAL ELECTRIC COMPANY [US/ US]; I River Road, Schenectady, NY 12345 (US).

17 NOV 1988 (72) Inventor: PRATT, Charles, Franklyn P.O. Box 1954, Pittsfield, MA 01201 (US).

(74) Agents: KING, Arthur, International Patent Opera- AUSTRALIAN tion, General Electric Company, 1285 Boston Avenue, Bridgeport, CT 06602 (US) et al. 10 OCT 1988 PATENT OFFICE (54) Title: IMPACT MODIFIED POLYESTER COMPOSITIONS WITH IMPROVED HEAT RESISTANCE (57) Abstract Thermoplastic polyester molding compositions impact-modified by glycidyl methacrylate-grafted EPDM rubbers exhibit improved heat resistance with the addition of glassy polymers, thermoplastic polymers having amorphous glass transition temperatures above about 100 0 C, poly(styrene-acrylonitrile), aromatic poly(sulfone), poly(phenylene ether) and/or aromatic poly(carbonate) without significantly diminishing the impact strength or knit-line characteristics.

I

L

I WO 88/07065 PCT/US88/00677 -1- "IMPACT MODIFIED POT wSTER COMPOSITIONS WITH IMPROVED HEAT RESISTANCE" This invention relates to heat resistant impact modified thermoplastic molding compositions and, more particularly, to glycidyl methacrylate or glycidyl acrylate grafted EPDM impact modifiers for thermoplastic polyester, copolyester and polyblend molding compositions that also include glassy polymers to improve heat resistance.

BACKGROUND OF THE INVENTION High molecular weight linear polyesters and copolyesters of glycols and terephthalic or isophthalic acid have been available for a number of years. These are described inter alia in Whinfield et al., U.S. 2,465,319, and in Pengilly, U.S. 3,047,539. These patents disclose that the polyesters are particularly advantageous as film and fiber formers.

With the development of molecular weight control, the use of nucleating agents and two-step molding cycles, poly(ethylene terephthalate) or PET has become an important constituent of injection moldable compositions. Further, poly(l,4-butylene terephthalate)' or PBT, because of its very rapid crytallization from the melt, is uniquely useful as a component in such compositions. Work pieces molded from such polyester resins, in comparison with other thermoplastics, offer a high degree of surface hardness and abrasion resistance, high gloss and lower surface friction.

Furthermore, in particular, poly(1,4-butylene terephthalate) is much simpler to use in injection molding techniques than poly(ethylene terephthalate). For example, it is possible to injection mold poly(l,4-butylene terephthalate) at low mold temperatures of from about 300 to 60 0 C. to produce highly crystalline, dimensionally stable moldings in short cycle times. Because of the high rate of crystallization, even at low temperatures, no difficulty is encountered in removing the moldings from the molds. Additionally, the WO 88/07065 PCT/US88/00677 -2dimensional stability of poly(l,4-butylene terephthalate) injection moldings is very good even at temperatures near or well above the glass temperature of poly(l,4-butylene terephthalate).

However, the impact resistance of unmodified polyesters is relatively low at room temperature and below. Thus for many applications, it is desirable to have polyesters which are impact resistant at relatively high and relatively low ambient temperatures. Yet, the other mechanical properties such as modulus of elasticity, tensile strength at yield and at break should be impaired either not at all or only to an acceptable degree.

It has been recommended in various places to improve the impact resistance of polyesters by adding other polymers including rubbery interpolymers and copolymers.

Specifically, the impact strength of thermoplastic linear crystalline polyesters, including poly(l,4-butylene terephthalate), has been improved by the incorporation therein of an ethylenepropylene nonconjugated diene rubbery terpolymer (EPDM). Although EPDM is capable of impact-modifying PBT polyester compositions, Coran et al., U.S. 4,141,863 and Tanaka et al., U.S. 4,290,927, such compositions often suffer from "incompatibility" resulting in streaks or delamination of molded or extruded parts.

In Hepp, European Patent Application 0 149 192, published July 24, 1985, there is disclosed a thermoplastic molding composition consisting of a thermoplastic resin, polyester, copolyester or block copolyester and a rubbery polymer comprising EPDM epoxidized with, mchloroperoxy-benzoic acid and, optionally, a sec)nd nonrubbery, glassy thermoplastic polymer, aromatic polycarbonate, to enhance surface characteristics and/or capability. The examples given by this reference in Tables 1, 2 and 3 do not, however, exhibit a combination of good impact strength and acceptable knit-line characteristics nor ".4MMOM NMM qMMMPWXi- 5r WM I 0137s:AB 3 is there any indication that heat resistance is in any way enhanced by the addition of the polycarbonate.

Epstein, U.S. 4,172,859, discloses the use of glassy random copolymers, polycarbonate with PET or PBT which contain various polar monomers. He also alludes to the use of materials grafted with various polar monomers, e.g., glycidyl methacrylate (GMA), to impact modify thermoplastic polyesters including PBT and PET, and polycarbonate.

However, this patent does not deal with and therefore fails to recognize one factor that is critical to the function of EPDM-g-GMA materials as impact modifiers for PBT and polycarbonate systems. It does not recognize the benefits of reactive glycidyl (meth)acrylates as graft monomers over nonreactive polar monomers such as maleic anhydride or n-vinyl pyrrolidone.

In the prior disclosures of U.S. Patent Specification 4948842, Australian Patent Specification 605248, and Australian Patent Specification 605596, there are taught rubbery glycidyl methacrylate (GMA) grafted EPDM impact modifiers for polyester resins. In the specific examples, materials are described with high impact strengths. Good results are obtained with GMA contents of above 1% by weight in the rubbery modifier. However, no hint or suggestion is given in such prior disclosures that other thermoplastic resins, especially glassy resins, can be added to improve properties such as heat resistance.

It has now been surprisingly discovered that thermoplastic polymers having an amorphous glass transition temperature above about 100°C. can be incorporated in relatively small amounts into thermoplastic polyester compositions comprising glycidyl methacrylate grafted EPDM (EPDM-g-GMA) WO 88/07065 PCT/US88/00677 -4impact modifiers, and that such compositions will exhibit improved heat resistance as measured conveniently by heat distortion, despite the fact that a major proportion of the composition comprises polyesters having a relatively low glassy transition temperature, below about 80 0 C. and especially below about 75 0 C. At the same time, the advantageous effect on heat resistance is obtained without diminishing significantly the impact strength and knit-line characteristics of such compositions.

While not intending to be bound by any particular theory underlying this invention, it is believed that the improved heat resistance of these impact-modified polyester compositions may be due to the reinforcing effect of small regions of glassy polymer in the matrix, offsetting the tendency of the polyester, PET or PBT, to soften at temperatures above their relatively low amorphous glass transition temperatures, which for PET is about 73 0 C. and for PBT is about 590C.

SUMMARY OF THE INVENTION In accordance with the present invention are provided heat resistant impact modified reinforced thermoplastic compositions comprising: a high molecular weight thermoplat.ic polyester resin having an amorphous glass transition temperature of below about an effective amount of an impact improving rubbery polymer comprising an EPDM terpolymer grafted with glycidyl methacrylate or glycidyl acrylate or a mixture thereof, alone, or grafted in further combination with a

C

1

-C

18 alkyl methacrylate or acrylate or a mixture thereof; and a small, effective amount of a heat resistance improving thermoplastic polymer having an amorphous glass transition temperature above about 100 0

C.

Preferred features of the invention are composit- L -LI- i C_ i)inr u 1 SWO 88/07065 PCT/US88/00677 ions as defined above wherein component comprises an amount of from about 30 to about 90 parts by weight, component comprises an amount of from about 10 to about parts by weight and component an amount of from about to about 15 parts by weight, based on a total composition of 100 parts by weight of and combined.

Particularly preferred are compositions as defined above wherein component is selected from the group comprising poly(styrene-acrylonitrile), aromatic poly(sulfone) poly(phenylene ether), aromatic poly(carbonate) or a mixture of any of the foregoing.

DETAILED DESCRIPTION OF THE INVENTION The high-molecular weight linear polyesters used as component in the practice of the present invention are polymeric glycol esters of terephthalic acid and isophthalic acid. They are available commercially or can be prepared by known techniques, such as by the alcoholysis of esters of phthalic acid with a glycol and subsequent polymerization, by heating glycols with free acids or with halide derivatives thereof, and similar processes. These are described in U.S.

2,465,319 and U.S. 3,047,539, and elsewhere.

Although the glycol portion of the polyester can contain from 2 to 10 carbon atoms, it is preferred that it contain from 2 to 4 carbon atoms in the form of linear methylene chains.

Preferred polyesters will be of the family consisting of high molecular weight, polymeric glycol terephthalates or isophthalates having repeating units of the general formula: 0 0 1C-- -0 CH 0 wherein n is a whole number of from 2 to 4, and mixtures of such esters, including copolyesters of terephthalic and isophthalic acids of up to about 30 mole percent isophthalic r j WO 88/07065 PCT/US88/00677 -6units.

Especially preferred polyesters are poly(ethylene terephthalate) and poly(l,4-butylene terephthalate).

Illustratively, high molecular weight polyesters will have an intrinsic viscosity of at least about 0.7 deciliters/gram and, preferably, at least 0.8 dqciliters/gram as measured in a 60:40 phenol-tetrachloroethane mixture at 30 0

C.

At intrinsic viscosities of at least about 1.0 deciliters/ gram, there is a further enhancement of toughness of the present compositions.

Copolyesters useful for the invention are preferably prepared from terephthalic acid and/or isophthalic acid and/or a reactive derivative thereof and one or more glycols, which may be a straight or branched chain aliphatic/cycloaliphatic glycol. Illustratively, the glycol will be ethylene glycol; 2-methyl-l,3-propanediol, 1,4-butanediol; 1,6-hexanediol; 1,9-nonanediol; 1,10-decanediol; neopentylglycol; 1,4-cyclohexanediol; 1,4-cyclohexanedimethanol; a mixture of any of the foregoing, or the like. Illustrative of suitable aliphatic dicarboxylic acids for the mixed aromatic/aliphatic embodiments ar suberic, sebacic, azelaic, and adipic acids and the like.

The copolyesters may be prepared by ester interchange in accordance with the standard procedures. The copolyesters may preferably be derived from at least butylene terephthalate units.

The block copolyesters useful in the composition of this invention are prepared by the reaction of terminally reactive poly(l,4-butylene terephthalate), .preferably of low molecular weight, and a terminally reactive copolyester or aliphatic polyester or both in the presence of a catalyst for transesterification, such as zinc acetate, manganese acetate, titanium esters, and the like. The terminal groups can comprise hydroxyl, carboxyl, carboalkoxy, and the like, including reactive derivatives thereof. After initial mixing, WO 88/07065 PCT/US88/00677 -7polymerization is carried out under standard conditions, 2200 to 280 0 in a high vacuum, 0.1 to 2 mm Hg, to form the block copolymer of minimum randomization in terms of distribution of chain segments. The result of reaction between two terminally reactive groups, of course, must be an ester linkage. These copolyesters are described in a German Patent application P 27 56 167.7.

The copolyester designated component of these block copolyesters may be terminally reactive segments of copolyesters as described above. These copolyesters are most preferably derived from an aliphatic glycol and a mixture of aromatic and aliphatic dibasic acids in which the mole ratio concentration of aromatic to aliphatic acids is from between 1 to 9 to about 9 to 1, with an especially preferred range being from about 3 to 7 to about 7 to 3.

The terminally reactive aliphatic polyester component of these block copolyesters will contain substantially stoichiometric amounts of the aliphatic diol and the aliphatic dicarboxylic acid.

In addition to their ease of formation by well known procedures, both the aforementioned aromatic/aliphatic copolyesters and aliphatic polyesters are commercially available.

One source for such materials is the Ruco Division/Hooker Chemical Company, Hicksville, New York, which designates its compounds as "Rucoflex".

The block copolyesters used in the invention preferably comprise from about 95 to about 50 parts by weight based on the block copolyester of poly(l,4-butylene terephthalate) segments. The poly(l,4-butylene terephthalate) blocks, before incorporation into the block copolyesters, will preferably have an intrinsic viscosity of about 0.1 dl./g. and, preferably, between about 0.1 and about 0.5 as measured in a 60:40 mixture of phenol-tetrachloroethane at 30 0 C. The balance 50 to 5 parts by weight of the copolyester will comprise blozks of the aforementioned aromatic/aliphatic VVIJrrr PCT/nr Y"-U88/00677"~1 wu aso/u/UOS PCT/US88/00677 -8copolyesters and/or aliphatic polyesters.

As will be understood by those skilled in the art, the poly(l,4-butylene terephthalate) block can be straight chain or branched, by use of a branching component, from about 0.05 to about 1 mole percent, based on terephthalate units of a branching component which contains at least 3 ester-forming groups. This can be a polyol, e.g., pentaerythritol, trimethylol-propane, and the like or a polybasic acid compound, trimethyl trimestate, and the like.

Blends of the foregoing homopolymers, copolymers and/or block copolymers or derivatives thereof are also useful for the invention.

The glycidyl ester grafted terpolymer additives used in the rubbery polymeric impact modifier in this invention may be prepared from any of the well known EPDM terpolymer rubbers. EPDM terpolymers useful for preparing the grafted materials used in the invention are commercially available, Copolymer Corp. (EPSYN* 55), or may be prepared using a Ziegler-type catalyst. The preparation of typical EPDM terpolymers is described, for example, in Gresham et al., U.S. 2,933,480; Tarney, U.S. 3,000,866; Guglielmino et al., U.S. 3,407,158; Gladding, U.S. 3,093,621 and U.S. 3,379,701. These terpolymers are characterized by the absence of chain or backbone unsaturation and the presence of sites of unsaturation in groups which are pendant to or are in cyclic structures outside of the main polymer chain.

Useful EPDM terpolymers for the production of the glycidyl ether grafted terpolymers used in this invention comprise ethylene, a C 3 to C 1 6 straight or branched chain alpha-olefin, preferably propylene, and a non-conjugated diolefin. Satisfactory nonconjugated dienes that may be used as the third monomer in the terpolymer include straight chain dienes such as 1,4-hexanediene, cyclic dienes such as cyclooctadiene and bridged cyclic dienes such as ethylidene SWO 88/07065 PCT/US88/00677 -9norbornene.

Preferred EPDM terpolymers are comprised of about 10-95, preferably 45-70 mole percent, by weight ethylene, about 5 to 90, preferably 30-55 mole percent polypropylene and a minor amount of diene monomer, most preferably a polyunsaturated bridged ring hydrocarbon or halogenated derivative thereof, most preferably 5-ethylidene-2-norbornene.

These EPDM terpolymers have a melt index of approximately 79 min., a Mooney viscosity of approximately 78 and a gram molecular weight of about 21,600.

The backbone rubber is subsequently graft modified with a graft monomer of epoxy functional acrylate or methacrylate. Although grafting may occur by various reaction mechanisms at practically any point on the backbone rubber, generally, the grafting takes place at an unreacted point of unsaturation on the polyene. For this reason, it is desirable to make use of an ethylene, mono-olefin, polyene backbone rubber having at least two unsaturated carbon-to-carbon linkages per 100 carbon atoms and little additional benefit is derived from the use of unsaturated backbone rubber having more than 20 carbon-to-carbon double bonds per 1000 carbon atoms. In the preferred practice of this invention, use is made of an unsaturated rubber having from 4-10 carbon-tocarbon double bonds per 1000 carbon atoms.

The point of ethylenic unsaturation on the epoxy functional graft monomer must be sufficiently reactive to react directly with the unsaturation of the polyene; or to react with a graft chain originating at, or for combination with, the polyene unsaturation. Such levels of reactivity require the alpha-beta situation of the ethylenic unsaturation as found in, for example, an epoxy functional esters of acrylic acid or alkyl acrylic acid. A free radical initiator, such as a dialkyl peroxide may be used to promote the graft reaction. Such initiator is generally used in an amount within the range of 1-5 parts per 100 parts by weight J~L, ui.u. I r I WO 88/07065 PCT/US88/00677 of the unsaturated rubber, and preferably in an amount within the range of 1-2 percent by weight.

Preferred as the graft monomer herein is glycidyl methacrylate (GMA).

The graft chain formed by the grafting process on the backbone rubber need not be a homopolymer or even be of entirely epoxy functional graft monomers. For example, combinations of the two above-mentioned epoxy functional graft monomers may be used as well as combinations of either or both with other C 1

-C

1 8 alkyl acrylates or methacrylates, wherein C 1

-C

1 8 may be straight chain or branched, e.g., methyl, ethyl, isopropyl, 2-ethyl-hexyl, decyl, n-octodecyl, and the like. Particularly useful such comonomer grafts are grafts of glycidyl acrylate and/or glycidyl methacrylate and methyl methacrylate.

It is preferred in the present invention that the gel content of the elastomeric material be controlled either during polymerization or in subsequent processing to achieve a value of greater than about 10% by weight and less than 80%. With a gel content too low impact strength is high, but knit line strength is low. With a gel content too high, both impact strength and knit line strength not as high as desirable.

Gel content in an especially convenient analysis, according to ASTM D-3616, is measured by the weight percent of remaining elastomeric material after extraction in hexane or toluene. Gel content is an indication of the degree of cross-linking in the elastomeric material. Of course, per- Ssons skilled in the art are familiar with a variety of ways 30 to control the degree of cross-linking and thus the gel content can be determined by numerous other methods. The crosslink reaction may be a direct rubber backbone to rubber backbone joining, an epoxy functionality to epoxy functionality or rubber backbone joining, or a graft chain free radical addition to a second graft chain or to a rubber backbone.

WO 88/07065 PCT/US88/00677 -11- Further, cross-linking may be achieved by the addition of a cross-linking agent to effectively achieve any of the above reactions. Thus, any of several steps to control gel content may be taken. Thermal aging will increase gel content. Increasing the amount of epoxy functional graft monomer will increase gel content. Increasing the amount of polyene monoene monomer in the rubber backbone will increase gel content.

The addition of a cross-linking agent will increase gel content. The use of graft monomers with greater tendency to cross-link will increase gel content, for example, a homopolymer graft of glycidyl acrylate will cross-link more readily than a homopolymer graft of glycidyl methacrylate or a copolymer graft of glycidyl acrylate and methyl methacrylate.

As stated above, gel content of the elastomeric material used in this invention should range up to no higher than about 80%. Although cross-linking can be carried on well past this level, as has been mentioned, high levels of cross-linking diminish the dispersibility of the elastomeric material and lead to non-uniform mixing. Also, such high levels of localized cross-linking will create brittle areas within the elastomeric material which will decrease rubbery character. It is apparent that cross-linking should be uniformly dispersed throughout the elastomeric material.

It is preferred in the present invention that the elastomeric material have an epoxy functionality of at least epoxy functionalities per 1000 carbon atoms, and preferably between about 5.0 and 13 epoxy functionalities per 1000 carbon atoms. Epoxy functionality means those epoxy sites which remain in the impact modifier resin after the loss of such functionalities as may react in the cross-linking reaction. In the instance of the use of GMA or GA as the epoxy functional graft monomer, a graft level of above about preferably above about and most preferably, above about 2% by weight is necessary to provide the minimum level of

A.-

i -a SWO 88/07065 PCT/US88/00677 I -12epoxy as shown above. The maximum is not particularly critical, up to 10-15% by weight can be used, although no particular advantage is achieved above about 10% by weight.

The grafting reaction may be carried out in solvent solution with the unsaturated rubber backbone present in a concentration which may range from 10-30 percent by weight, with constant stirring, at an elevated temperature within the range of 125-200 0 C. for a time ranging from 1/2 to 2 hours.

The reaction condition can be varied depending somewhat upon the type and amount of catalyst and temperature conditions, as is well known to those skilled in the art. Where high amounts of graft monomer are to be attached to the backbone rubber, it has been found to be advantageous to carry out the graft reaction in the melt state of the backbone rubber, i.e., extruder grafting. This process is simply performed by feeding the backbone rubber, an excess of graft monomer, and an appropriate catalyst to a melt extruder and mixing and reacting the feed components at an elevated temperature.

The heat resistance improving thermoplastic polymers useful as component in the practice of this invention comprise a range of materials that are well known to those skilled in this art. Generally these heat resistance improving polymers, also known as "glassy" polymers, have amorphous glass transition temperatures preferably above about 100 0

C.,

more preferably above about 110 0 C. Suitable as component (c) are such polymers including but not limited to polyphenylene oxides alone, or in combination with styrene resins, amorphous polyamides, polyamide-imides, polyaryl ethers, polycarbonates, polyetherimides, polyimides, styrene copolymers such as styrene-acrylonitrile (SAN), poilysulfones, and thermoplastic polyurethanes. Especially preferred are SAN copolymers, polysulfones, poly(polyphenylene ethers) and polycarbonates available respectively under the tradenames TYRIL'880 (Dow Chemical), UDEL* 2100 (Union Carbide), PPO" and LEXAN*131 (General Electric Company). The glass transition tempera- WO 88/07065 PCT/US88/00677 V -13tures (Tg) for these preferred glassy polymers are all above 100'C., Poly-SAN, 110 0 polysulfone, 190°C.; poly- (phenylene ether), 110-135°C.; and poly(bisphenol A carbonate), 1500C. Unsuitable as component herein are crystalline polymers such as crystalline nylons and crystalline poly(phenylene sulfides). Also unsuitable polymers include acrylics, polyacrylonitrile (PAN), polystyrenes, styrenemethyl-methacrylate copolymers, and polyvinyl ,:hloride polymers and copolymers. The latter all have amorphous glass transition temperatures of below about 100 0 C. and will not be suitable.

In general, the quantity c the glassy polymer component will not be substantial in comparison to the rest of components and Typically, only a heat resistance improving amount of the glassy polymer is required. Generally, the polyester component will comprise an amount of from about 30 to about 90 parts by weight, the rubbery polymer of component will comprise an amount of from about 10 to about 55 parts by weight, and component will comprise an amount of from about 0.5 to about 15 preferably 1 to 10 parts by weight, based on a total composition of 100 parts by weight of and combined. In certain embodiments of this invention, the rubbery polymer of component may comprise a "preblend" of EPDM grafted with giycidyl methacrylate and the polyester resin, PBT in a ratio of from about 1:1 to about 10:1 of the impact modifier to the polyester. As will be exemplifed in the next section, this impact modifying "preblend" can comprise EPDM-g-GMA and PBT in a ratio of 3:1 respectively.

The above described elastomeric material is physically dispersed in a thermoplastic polymer melt to form discrete particles of rubbery polymer in a continuous phase of a thermoplastic matrix resin or blend. At least an impact strength improving amount of elastomeric material is dispersed in the matrix resin. Generally, this requires that the elastomeric SWO 88/07065 PCT/US88/00677 -14material constitute at least 1.5 percent by weight, preferably to 80 percent, most preferably 10 to 55 percent, by weight based on total thermoplastic content, including elastomeric material, of the molding composition. It will be apparent that, while the indicated composition range is optimum for making toughened rigid plastic articles, acceptable molding materials can still be made from mixtures with rubber contents much higher than this range. Thermoplastic elastomer type molding compounds are produced when the elastomer content exceeds 55 weight percent, and even mixtures above the phase inversion composition, those in which the thermoplastic resin phase is sem 6r noncontinuously interdispersed in a rubbery polymer matrix can be used to make flexible molded articles with exc'ellent properties. 80 weight percent elastomer is a typical upper limit. Compounding of the rubber, thermoplastic resin and reinforcing agent is carried out by standard techniques, for example, by simple melt blending or dry mixing and melt extruding at an appropriate elevated temperature for any given thermoplastic matrix. The resultant admixture is then molded into a thermoplastic piece of specific dimensions or further extrudeJ into a film or sheet product.

It is important to the final properties of molded parts containing elastomeric material that there is sufficient mixing in the extrusion of the resin melt. Herein, several reactions have been taught or suggested to take place in the extruder and such are, of course, effected by mixing as well as residence time in the extruder. Thus, thorough mixing of the polymer melt is suggested and, depending upon the equipment employed, two successive extrusions of the melt.

may be required.

As has been mentioned, in preferred compositions the particle size of the rubber grafted with glycidyl esters will be selected to provide that at least 60 weight percent of such particles, and preferably more than 70 weight percent -1-1 1- 6 WO 88/07065 PCT/US88/00677 of them are greater than 1 micron in diameter. Such compositions combine optimum notched Izod impact strength, with knit-line strength, and these are vastly superior to those obtained with compositions wherein, for example, only about 50 weight percent of the particles exceed 1 micron in diameter. Particle size can be measured in any of the ways known in this art, but an especially convenient way is to use a computerized particle size analyzer to measure photomicrographs of scanning electron microscopy (SEM) images.

Compounding can be carried out in conventional equipment. For example, after pre-drying the thermoplastic polyester resin, at 125 0 C. for 4 hours, a single screw extruder is fed with a dry blend of the polyester, glassy -,lymer and the additive ingredients, antioxidant and/ or stabilizer, the screw employed having a long transition and metering section to insure melting. On the other hand, a twin screw extrusion machine, a 28 mm or 30 mm or even mm Werner Pfleiderer machine can be fed with resin and additives at the feed port. In either case, a generally suitable machine temperature will be about 450°F. to 570°F.

2he compounded composition can be extruded and cut up into molding components such as conventional granules, pellets, etc., by standard techniques.

The compositions of this invention can be molded in any equipment conventionally used for thermoplastic compositions. For example, with poly(l,4-butylene terephthalate) good results will be obtained in an injection molding machine, of the Newbury type or a Cincinnati 75 ton type with conventional cylinder.temperature, 450 0 F. and conventional mold temperatures, 150 0

F.

It is to be understood that the foregoing compositions may contain other additives known in the art, including, but without limitation, mold release agents, flow promoters, antioxidants, coloring agents, coupling agents, and stabilizers including transesterification stabilizers. The l WO 88/07065 PCT/US88/00677 -16elastomeric containing molding compositions of this invention may be used as molding pellets and may contain pigments, dyes, stabilizers, plasticizers, and the like. One may readily determine which are necessary and suitable for a particular application.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples illustrate the preferred invention. The claims are not to be construed to be limited by them in any manner whatsoever.

EXAMPLES 1-3 Impact modified PBT compositions in accordance with the present invention were blended and suitable workpieces were molded for testing. The impact modifier was used as a 75/25 w/w concentrate in PBT. Blends were tumble-mixed and extruded on a WP-30 twin screw extruder. The materials were subsequently dried and molded on a 75 ton Cincinnati injection molding machine. Composition3 and results are set forth in Table 1.

TABLE 1: Thermoplastic Compositions PBT/ EPDM-g-GMA TerDolymers/Glassy Polymers Example Composition (parts by wei.ht) Poly(l,4-butylene terephthalate)a EPDM-g-GMAb EPDM-g-GMAc Poly(styrene-acrylonitrile)d Polysulfonee Poly(bisphenol A carbonate) f Hindered Phenol Antioxidant Hindered Phenol Antioxidant/ Stabilizer

IA*

82.75 17.25 78 78 78 18 18 18 4 4 4 0.3 0.3 0.3 (0.3/ 0.95) Notched Izod, ft.lb./in.

Unnotched Izod, ft.lb./in.

15.5 21.3 14 .5 16.1 12.4 21.7 1.25 13 .8 31.1 SWO 88/07065 PCT/US88/00677 -17- TABLE 1: (CONTINUED): Heat Distortion Temperature 66 psi, oC 95 134 136 127 OF 203 273 277 261 Control a VALOX*315, General Electric Company b Prepared from Copolymber Rubber Co. EPSYN*4906 EPDM rubber and glycidyl methacrylate using dicumyl peroxide initiator, 6.4% GMA content.

c Prepared from Copolymber Rubber Co. EPSYN*55 EPDM rubber and glycidyl methacrylate using 2,5-dimethyl-2,5-di(tbutyl peroxy) hexane initiator, 7.5% GMA content.

d TYRIL*880, Dow Chemical Company e UDEL*2100, Union Carbide Company f LEXAN*131, General Electric Company The results above indicate that the heat resistance of EPDM-g-GMA impact modified polyester compositions is improved with the addition of a glassy polymer in accordance with this invention.

The above patents, applications and/or publications are incorporated herein by reference.

Many variations will suggest themselves to those skilled in the art in light of the above, detailed description. For example, instead of using poly(l,4-butylene terephthalate) as component other polyester resins can be used, such as poly(ethylene terephthalate) or copolyesters derived from one or more aliphatic and/or aromatic dicarboxylic acids and one or more straight or branched chain aliphatic or cycloaliphatic glycols including random or block copolyesters. Instead of injection molding, blow molding, including injection blow molding can be used. Instead of glycidyl methacrylate, a mixture of glycidyl methacrylate and methyl methacrylate, a mixture of glycidyl acrylate and methyl methacrylate or a mixture of glycidyl methacrylate and octadecyl methacrylate can be used. Instead of poly- PCT/US88/00677

I~

[i 0O88/07065 -18- (styrene-acrylonitrile), polysulfone or polycarbonate as glassy polymers, other thermoplastic polymers such as poly- (2,6-dimethyl-l,4-phenylene ether) resin can be added in effective amounts to improve heat resistance. Furthermore, other additives known to those skilled in the art may be added in conventional amounts to the impact modified compositions herein including but without limitation, antioxidants, nucleating agents, mold release agents, flow promoters, coloring agents, flame retardants, coupling agents and stabilizers.

All such obvious variations are within the full intended scope of the appended claims.

0134s:AB 18a- 1. A heat resistant impact-modified thermoplastic composition comprising, per 100 parts by weight of components and combined: 30 to 90 parts of a high molecular weight thermoplastic polyester resin having an amorphous glass transition temperature below 80 deg. C., 10 to 55 parts of an impact improving rubbery EPDM terpolymer grafted with glycidyl acrylate or t glycidyl methacrylate or a mixture thereof, and 0.5 to 15 parts of a heat resistance improving thermoplastic polymer having an amorphous glass transition temperature greater than 100 deg. C.

S2. A composition as defined in claim 1 wherein the amorphous glass transition temperature of component is above 110 0

C.

Claims (13)

1. A heat resistant impact-modified thermopl'astic composition comprising: a high molecular weight them6oplastic polyester resin having an amorphous glass transition temper- ature of below about an effective amountfof an impact improving rubbery polymer comprising an EPDM terpolymer grafted with glycidyl methacrylate or glycidyl acrylate or a mixture thereof, alone, or grafted in' further combination with a C 1 -C 18 alkyl methacrylate' or acrylate or a mixture thereof; and /a small, effective amount of a heat resis- tance improving hermoplastic polymer having an amorphous 7- glass transiion temperature above about 100 0 C. A composit 7n as defined in Claim 1 wherein the amorphous glass transition temperature of component is above about 110 0 C.

3. A composition as defined in Claim 1 wherein said polyester is selected from the group comprising poly- (1,4-butylene terephthalate), poly(ethylene terephthalate), copolyesters or any combination thereof.

4. A composition as defined in Claim 1 wherein said polyester is poly(1,4-butylene terephthalate). A composition as defined in Claim 1 wherein the thermoplastic polyester resin is a copolyester derived from one or more aliphatic and/or aromatic dicarboxylic acids and one or more straight or branched chain aliphatic or cycloaliphatic glycols.

6. A composition as defined in Claim 3 wherein the copolyester is a random copolyester.

7. A composition as defined in Claim 3 wherein the copolyester is a block copolyester. L..r Y I I- -I 1 Ii 1a 00 1 04, 0 a 00: 0134 __None-, Ls:AB 20

8. A composition as defined in claim 3 wherein the thermoplastic polyester resin is a polyblend of poly (1,4-butylene terephthalate) and poly(ethylene terephthalate).

9. A composition as defined in claim 1 wherein the grafted EPDM terpolymer is derived from 45 to 70 mole percent ethylene, 30-55 mole percent propylene and a minor amount of 5-ethylidene-2-norbornene. A composition as defined in claim 1 wherein said heat resistance improving thermoplastic polymer is selected from the group comprising poly(styrene-acrylo-nitrile), aromatic poly(sulfone), poly(phenylene ether), aromatic poly(carbonate) or a mixture of any of the foregoing. *00006 0 0 00 a a 0 0 S 0134s:AB 21

11. A process for producing a heat resistant impact-modified thermoplastic composition comprising melt blending: 30 to 90 parts of a high molecular weight thermoplastic polyester resin having an amorphous glass transition temperature below 80 deg. C., 10 to 55 parts of an impact improving rubbery EPDM terpolymer grafted with glycidyl acrylate or glycidyl methacrylate or a mixture thereof, and 0.5 to 15 parts of a heat resistance improving thermoplastic polymer having an amorphous glass transition temperature greater than 100 deg. C.

12. A process as defined in claim 11 wherein the amorphous glass transition temperature of component is above 110°C.

13. A process as defined in claim 11 wherein said polyester is selected from the group comprising poly(1,4-butylene terephthalate), poly(ethylene terephthalate), copolyesters or any combination thereof.

14. A process as defined in claim 13 wherein said polyester is poly(1,4-butylene terephthalate).

15. A process as defined in claim 11 wherein the grafted EPDM terpolymer is derived from 45 to 70 mole percent ethylene, 30-55 mole percent propylene and a minor amount of 5-ethylidene-2-norbornene. 0*. S* S -Y 0134s:AB 22

16. A process as defined in claim 11 wherein said heat resistance improving thermoplastic polymer is selected from the group comprising poly(styrene-acrylo-nitrile), aromatic poly(sulfone), poly(phenylene ether), aromatic poly(carbonate) or a mixture of any of the foregoing. DATED this 9th day of May, 1991. GENERAL ELECTRIC COMPANY o* By Its Patent Attorneys .o ARTHUR S. CAVE CO. Seo 0 S S S bout b ic Cmpany) Th glass trLIanii ntempra-L 35 (General Electric Company). The glass transition tempera- AC~ /i Y113-LII~LI-1~I~ ii--i i INTERNATIONAL SEARCH REPORT International ApplIcatIon No PCT/US 88/00677 I. CLASSIFICATION OF SUBJECT MATTER (itseveral cassification symbols apply, Indicate ail) According to International Patent Classification (IPC) or to both National Classification and IPC 4 1 IPC C 08 L 67/02; C 08 L 51/06 H- FIFLOAe rv l rrs vn Minimum Documentation Searched 7 Classification System Classification Symbols 4 IPC C08L Documentation Searched other than Minimum Documentation to the Extent that such Documents are Included in the Fields Searched 0 ill. DOCUMENTS CONSIDERED TO BE RELEVANT' Category Citation of Document, 11 with Indication, wheseappropriate, of the relevant passages 12 Relevant to Claim No. 13 Y WO, A, 86/04076 (COPOLYMER RUBBER AND 1-25 CHEMICAL CORP.) 17 July 1986, see claims 1-36 cited in the application Y FR, A, 2311808 DU PONT DE NEMOURS 1-25 AND CO.) 17 December 1976, see claim 1; page 4, lines 28-36; page 12, lines 13-14 cited in the application A EP, A, 0149192 (GENERAL ELECTRIC) 24 July 1-25 1985, see claims 1-30 cited in the application Special categories of cited documents: 1' later document published after the international fling date document defining the general state of the art which is not or priority date and not In conflict with the application but considered to be of particular relevance cited to understand the principle or theory underlying the earlier document but published on or after the Inturrational "X I document of particular relevance; tle claimed invention cannot be coisidered novel or cannot be considered to document which may throw doubts on priority claim(s) or involve an inventive step which is c ited to establish the publication date ot another document of particular relevance;'the claimed Invention citation or other spaciai reason (as specified)cannot be considered to involve an inventive step when the document referring to an oral disclosure, use, exhibition or document Is combined with one or more other such docu other means menta, such combination being obvious to a person skilled document published prior to the international filing date but in the art. later than the priority date claimed docunent member Of the same patent family IV. CERTIFICATION Date of the Actual Completion of the international Search 3rd August 1988 Date of Miling of this International Search Report International Searching Authority EUROPEAN PATENT OFFICE Form PCT/ISA/210 (second sheet) (January 1965) p- -Q I ANNEX TO THE INTERNAT. JNAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. US 8800677 SA 22537 This annex lists the patent family members relating to the patent documents cited in the above-mentioned international search report. Tihe members are as contained in the European Patent Office EDP file on 18/08/88 The European Patent Office is in no way liable for these particulars which are merely given for the purpose of information. WO-A- 8604076 17-07-86 EP-A- 0209566 28-01-87 FR-A- 2311808 17-12-76 NL-A- 7605494 25-11-76 0E-A- 2522876 09-12-76 GB-A- 1552637 19-09-79 US-A- 4172859 30-10-79 JP-A- 51144452 11-12-76 CA-A- 1087777 -14-10O-80 EP-A- 0149192 24-07-85 JP-A- 60168750 02-09-85 w For more details about this annex see Official Journal of the European Patent Office, No. 12/82.