THERMOPLASTIC COPOLYETHERIMIDE ESTER ELASTOMER-ACRYLATE RUBBER COMPOSITIONS

Abstract: Thermoplastic elastomer compositions are disclosed which comprise a thermoplastic copolyetherimide ester blended with a crosslinkable alkylacrylate rubber component. The rubber is subject to crosslinking during melt mixing resulting in a thermoplastic processable material.

Description: THERMOPLASTIC COPOLYETHERIMIDE ESTER ELASTOMER-ACRYLATE RUBBER COMPOSITIONS CROSS REFERENCE TO RELATED APPLICATION The present application is a continuation-in-part o copending United States Patent Application Serial No 07/467,677, filed January 19, 1990. FIELD OF THE INVENTION The present invention relates to blends of copolyetherimide ester elastomer and a rubbery crosslinkabl alkylacrylate elastomer. BACKGROUND OF THE INVENTION Thermoplastic elastomers of the type known a polyetherimide esters provide a variety of unique an excellent properties and are particularly useful in extrusio and molding applications. Polyetherimide esters prepared from diols dicarboxylic acids and polyoxyalkylene diimide diacids ar thermoplastic elastomers having an excellent combination o stress-strain properties, low tensile set, high meltin temperatures and excellent strength, toughness and flexibilit properties. All of these properties are variously useful i many elastomer applications. Copolyetherimide ester elastomer also process well, due to their rapid crystallization rate an excellent moldability characteristics. Elastomers with the lo flexural modulus of polyetherimide esters in combination wi any of the aforementioned advantageous properties have gain wide acceptance in the field of elastomers. Nonetheless, it has now been found th polyetherimide esters can be improved or enhanced for certa applications, especially with respect to improving t "softness" (lower durometer) of the elastomer, while retaini satisfactory tensile properties. The improvements a accomplished by blending a rubbery crosslinkable alkylacryla elastomer with the polyetherimide ester and dynamical crosslinking the former. Work has been patented in which a rubber is mix with a thermoplastic resin and subsequently crosslinked while the ingredients are being mixed. This is known in the art as "dynamic curing" or "dynamic vulcanization". Gessler et al.. United States Patent No. 3,037,954 demonstrated "dynamic curing" of a butyl rubber/polypropylene blend. Fischer, United States Patent No. 3,758,643, partially cured EPDM rubber in the presence of a polyolefin. Other polyolefin/rubber vulcanizates in which the rubber is polybutadiene, natural rubber, isoprene and EPDM are disclosed in United States Patent Nos. 4,104,210; 4,130,535; and 4,311,628. In United States Patent No. 4,594,390, a continuous process for preparing EPDM/polypropylene dynamic vulcanizates is reported. The Monsanto Company commercially produces an EPDM/polypropylene dynamic vulcanizate under the trade name "SANTOPRENE", and a nitrile rubber/polyolefin dynamic vulcanizate under the trade name "GEOLAST". Further, United States Patent No. 4,801,647 discloses an EPDM/crystalline polyolefin dynamic vulcanizate. Dynamic vulcanization has also been disclosed employing copolyesters. European patent, EP 0 293 821 A2, discloses a multiblock copolyester melt mixed with polychloroprene rubber which is then crosslinked during mixing. In United States Patent No. 4,739,012, a segmented thermoplastic copolyester is blended with a second composition which is a blend of two partially crosslinked polymers, such as PVC or PVDC and a copolymer of ethylene and one or more ethylenically unsaturated comonomers prepared by dynamic vulcanization. Acrylic rubbers are also known to be employed in thermoplastic dynamic vulcanizates. Coran et al.. Rubber Chem. and Tech., 55, 116 (1982), disclose a matrix of polymers and rubbers used in the preparation of dynamic vulcanizate compositions in which polyacrylate rubber was used; however, not with copolyetherimide esters. Wolfe, United States Patent No. 4,782,110 discloses dynamically vulcanizing ethylene-alkylacrylate copolymer rubbers with crystalline polyolefins. Coran et al.. United States Patent No. 4,327,199, disclose employing, an ethylene-acrylic type copolymer rubber containing free carboxylic moieties in blends with polyesters such as PBT. A metal oxide is used as a source of metal ions to neutralize the pendant acid groups, forming an ionomeric network structure as distinguished from covalent bond formation. In Coran et al.. United States Patent Nos. 4,310,638 and 4,473,683 the ethylene acrylic copolymer is blended with a nylon resin and a metal oxide; and amorphous styrene based resins and a metal oxide, respectively. Also to be mentioned are United States Patent Nos. 4,116,914 (ethylene vinyl acetate rubber dynamically vulcanized with polyolefins) ; 4,480,074 (two step process for dynamically vulcanizing an EPDM/PP vulcanizate with additional EPDM); 4,226,953 (nitrile rubber dynamically vulcanized with styrene-acrylonitrile resins); 4,207,407 (chlorinated polyethylene dynamically vulcanized with nylon resins); 4,287,324 (epichlorohydrin rubber dynamically vulcanized with polyesters such as PBT); and 4,593,062 (mixture of halogenated butyl rubber and polychloroprene dynamically vulcanized with polyolefins such as PP and PE). Special mention is made of EPO 327 010 A2, ("EP O10") which discloses blends of polyether ester copolymers with polyacrylate elastomers. None of these however disclose a polyacrylate rubber which has been dynamically vulcanized with a thermoplastic copolyetherimide ester. It has now bee discovered and is shown in the examples hereinafter tha dynamically vulcanizing a polyacrylate rubber with thermoplastic copolyetherimide ester provides an elastome composition with improved softness while retaining excellen tensile properties. This is unexpected because th copolyether esters employed in EP '010 suffer from the loss o tensile properties to a much greater extent when mixed wit crosslinkable polyacrylate rubbers and dynamically vulcanized. SUMMARY OF THE INVENTION According to the present invention, there is provided a thermoplastic elastomer composition comprising: (A) a polyetherimide ester copolymer; (B) a crosslinkable rubbery alkylacrylate, and (C) a crosslinking agent. The polyetherimide ester copolymer can comprise the reaction product of (a) one or more low molecular weight diols; (b) one or more dicarboxylic acids; and (c) one or more polyoxyalkylene diimide diacids. Preferably the diol component (a) comprises from about 60 to about 100 mole percent 1,4-butanediol, the dicarboxylic acid component (b) comprises from about 60 to about 100 mole percent dimethyl terephthalate, and the polyoxyalkylene diimide diacid component (c) is . derived from trimellitic anhydride and a polyoxyalkyl diamine selected from the group consisting of polypropylene oxide . diamine and a copoly(ethylene oxide-propylene oxide) diamine having predominantly polyethylene oxide in the backbone. The preferred rubbery alkyl acrylate is based on repeating units comprising the formula: (CH,-CH) I c=o OC 2 H 5 The preferred crosslinking agent is sodium stearate. Also contemplated are thermoplastic elastomer compositions further comprising a filler such as a silica and a plasticizer. The preferred compositions comprise component (A) in an amount ranging from about 20 to about 99 parts by weight and component (B) in an amount ranging from about 80 to about 1 part by weight based upon 100 parts by weight of (A) and (B) together. Also according to the present invention, there is provided a process for producing a thermoplastic elastomer composition comprising: (I) mixing (i) a polyetherimide ester copolymer, and (ii) a crosslinkable rubbery alkylacrylate; and (II) curing the mixture obtained in step (I) by adding a crosslinking agent. Preferably, step (II) of the process further comprises adding an accelerator such as sulfur, sulfur donors, magnesium oxide, tertiary amines and mixtures of any of th foregoing. Most preferred are quaternary ammonium compounds. DETAILED DESCRIPTION OF THE INVENTION The polyetherimide esters useful in the practic of the present invention may be prepared from one or mor diols, one or more dicarboxylic acids and one or more hig molecular weight polyoxyalkylene diimide diacids. They are generally comprised of recurrin polyether imide ester structural units having the genera formula: wherein G is a divalent radical remaining after removal of th amino groups of a high molecular weight polyalkylene ethe diamine; R is a trivalent organic radical; R is the divalen radical remaining after the removal of the hydroxyl groups o a diol; and x is a whole number having a value of from 2 t about 40. Preparation of such materials is described i detail in U.S. Patent No. 4,556,705 of R.J. McCready, issue December 3, 1985 and hereby incorporated by reference. The poly(etherimide esters) used herein may b prepared by conventional processes, such as esterification an condensation reactions for the production of polyesters, t provide random or block copolymers. Thus, polyetherimide esters may be generally characterized as the reaction product of the aforementioned diols and acids. Preferred compositions encompassed by the present invention may be prepared from (a) one or more C 2 *-C 15 aliphatic or cycloaliphatic diols, (b) one or more C 4 -C 15 aliphatic, cycloaliphatic or aromatic dicarboxylic acids or ester derivatives thereof and (c) one or more polyoxyalkylene diimide diacids. The amount of polyoxyalkylene diimide diacid employed is generally dependent upon the desired properties of the resultant polyetherimide ester. In general, the weight ratio of polyoxyalkylene diimide diacid (c) to dicarboxylic acid (b) is from about 0.25 to 2.0, preferably from about 0.4 to about 1.4. Suitable diols (a) for use in preparing the compositions of the present invention include saturated and unsaturated aliphatic and cycloaliphatic dihydroxy compounds as well as aromatic dihydroxy compounds. These diols are preferably of a low molecular weight, i.e. having a molecular weight of about 250 or less. When used herein, the term "diols" and "low molecular weight diols" should be construed to include equivalent ester forming derivatives thereof, provided, however, that the molecular weight requirement pertains to the diol only and not to its derivatives. Exemplary of ester forming derivatives there may be given the acetates of the diols as well as for example ethylene oxide or ethylene carbonate for ethylene glycol. Preferred saturated and unsaturated aliphatic and cycloaliphatic diols are those having from 2 to 19 carbon atoms. Exemplary of these diols there may be given ethylene glycol; propane diol; butane diol; pentane diol; 2-methyl propane diol; 2,2-dimethyl propane diol; hexane diol; decane diol; 2-octyl undecane diol; 1,2-, 1,3-, and 1,4-cyclohexane dimethanol; 1,2-, 1,3-, and 1,4-dihydroxy cyclohexane; butene diol; and hexene diol. Especially preferred are 1,4-butane diol and mixtures thereof with hexane diol or butene diol, most preferably 1,4-butanediol. Aromatic diols suitable for use in the practice of the present invention are generally those having from 6 to about 19 carbon atoms. Included among the aromatic dihydroxy compounds are resorcinol; hydroquinone; 1,5-dihydroxy naphthalene; 4,4 '-dihydroxy diphenyl bis(p-hydroxy phenyl)methane and 2,2-bis(p-hydroxy phenyl)propane. Especially preferred diols are the saturated aliphatic diols, mixtures thereof and mixtures of a saturated diol(s) with an unsaturated diol(s), wherein each diol contains from 2 to about 8 carbon atoms. Where more than one diol is employed, it is preferred that at least about 60 mole %, based on the total diol content, be the same diol, most preferably at least 80 mole %. As mentioned above, the preferred compositions are those in which 1,4-butanediol is present in a predominant amount, most preferably when 1,4-butanediol is the only diol. Dicarboxylic acids (b) which are suitable for use in the practice of the present invention are aliphatic, cycloaliphatic, and/or aromatic dicarboxylic acids. These acids are preferably of a low molecular weight, i.e., having a molecular weight of less than about 300; however, higher molecular weight dicarboxylic acids, especially dimer acids, which are fully described in Kirk-Othmer,Encyclopedia of Chemical Technology/ 3rd Edition, vol. 7, John Wiley & Sons, N.Y., pp. 768-782, may also be used. The term "dicarboxylic acids" as used herein, includes equivalents of dicarboxylic acids having two functional carboxyl groups which perform substantially like dicarboxylic acids in reaction with glycols and diols in forming polyester polymers. These equivalents include esters and ester-forming derivatives, such as acid halides and anhydrides. The molecular weight preference, mentioned above, pertains to the acid and not to its equivalent ester or ester-forming derivative. Aliphatic dicarboxylic acids, as the term is used herein, refers to carboxylic acids having two carboxyl groups each of which is attached to a saturated carbon atom. If the carbon atom to which the carboxyl group is attached is saturated and is in a ring, the acid is cycloaliphatic. Aromatic dicarboxylic acids, as the term is used herein, are dicarboxylic acids having two carboxyl groups each of which is attached to a carbon atom in an isolated or fused benzene ring system. It is not necessary that both carboxyl groups be attached to the same aromatic ring and where more than one ring is present they can be joined by aliphatic or aromatic divalent radicals such as -0- or -S0 2 ~. Representative aliphatic and cycloaliphatic acids which can be used for this invention include sebacic acid, 1,2-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, adipic acid, glutaric acid, succinic acid, oxalic acid, azelaic acid, diethylmalonic acid, allylmalonic acid, 4-cyclohexane-l,2- dicarboxylic acid, 2-ethylsuberic acid, tetramethylsuccinic acid, cyclopentanedicarboxylic acid, decahydro-l,5-naphthalene dicarboxylic acid, 4,4'-bicyclohexyl dicarboxylic acid, decahydro-2,6-naphthalene dicarboxylic acid, 4,4- methylenebis(cyclohexane carboxylic acid), 3,4-furan dicarboxylic acid, and 1,1-cyclobutane dicarboxylic acid. Preferred aliphatic acids are cyclohexane dicarboxylic acids, glutaric acid, azelaic acid and adipic acid. Representative aromatic dicarboxylic acids which can be used include terephthalic acid, isophthalic acid, phthalic acid, bi-benzoic acid, substituted dicarboxy compounds with two benzene nuclei such as bis(p- carboxyphenyl)methane, oxybis(benzoic acid) , ethylene 1,2-bis- (p-oxybenzoic acid), 1,5-naphthγlene dicarboxylic acid, 2,6- naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, phenanthrene dicarboxylic acid, anthracene dicarboxylic acid, 4,4'-sulfonyl dibenzoic acid, and halo and C 1 ~C 12 alkyl, alkoxy, and aryl ring substitution derivatives thereof. Hydroxy acids such as p-(beta-hydroxyethoxy)benzoic acid can also be used provided an aromatic dicarboxylic acid is also present. Preferred dicarboxylic acids for the preparation of the polyetherimide esters of the present invention are the aromatic dicarboxylic acids, mixtures thereof and mixtures of one or more dicarboxylic acids with an aliphatic or cycloaliphatic dicarboxylic acid, most preferably the aromatic dicarboxylic acids. Among the aromatic acids, ' those with 8-16 carbon atoms are preferred, particularly the benzene dicarboxylic acids, i.e., phthalic, terephthalic and isophthalic acids and their dimethyl derivatives. Especially preferred is dimethyl terephthalate. Finally, where mixtures of dicarboxylic acids are employed in the practice of the present invention, it is preferred that at least about 60 mole %, preferably at least about 80 mole %, based on 100 mole % of dicarboxylic acid (b) be of the same dicarboxylic acid or ester derivative thereof. As mentioned above, the preferred compositions are those in which dimethyl terephthalate is the predominant dicarboxylic acid, most preferably when dimethyl terephthalate is the only dicarboxylic acid. Polyoxyalkylene diimide diacids (c) suitable for use herein are high molecular weight diimide diacids wherein the average molecular weight is greater than about 700, most preferably greater than about 900. They may be prepared by the imidization reaction of one or more tricarboxylic acid compounds containing two vicinal carboxyl groups or an anhydride group and an additional carboxyl group which must be esterifiable and preferably is nonimidizable with a high molecular weight polyoxyalkylene diamine. The polyoxyalkylene diimide diacids and processes for their preparation are more fully disclosed in McCready, European Patent No. 180,149, published May 7, 1986, and entitled "High Molecular Weight Diimide-Diacid Compounds Useful in the Preparation of Polyether Imide Ester(s) and Amide(s)", incorporated herein b reference. In general, the polyoxyalkylene diimide diacids useful herein may be characterized by the following formula: i il 0 0 wherein each R is independently a trivalent organic radical, preferably a C 2 to C 20 aliphatic, aromatic or cycloaliphatic trivalent organic radical; each R' is independently hydrogen or a monovalent organic radical preferably selected from the group consisting of C χ to C g aliphatic and cycloaliphatic radicals and C 6 to C 12 aromatic radicals, e.g. phenyl, most preferably hydrogen; and G is the radical remaining after the removal of the terminal (or as nearly terminal as possible) hydroxy groups of a long chain ether glycol having an average molecular weight of from about 600 to about 12000, preferably from about 900 to about 4000, and a carbon-to-oxygen ratio of about 1.8 to about 4.3. Representative long chain ether glycols from which the polyoxyalkylene diamine is prepared include poly(ethylene ether)glycol; poly(propylene ether) glycol; poly(tetramethylene ether)glycol; random or block copolymers of ethylene oxide and propylene oxide, including propylene oxide terminated poly(ethylene ether)glycol; and random ' or block copolymers of tetrahydrofuran with minor amounts of a second monomer such as methyl tetrahydrofuran (used in proportion such that the carbon-to-oxygen mole ratio in the glycol does not exceed about 4.3). Especially preferred poly(alkylene ether)glycols are poly(propylene ether)glycol and poly(ethylene ether)glycols end capped with poly(propylene ether)glycol or propylene oxide. In general, the polyoxyalkylf^-C 8 Jene diamines useful within the scope of the present invention will have an average molecular weight of from about 600 to 12000, preferably from about 900 to 4000. These may be characterized by the following general formula: H 2 N-G-NH 2 wherein G is the radical remaining after the removal of the amino groups of a long chain alkylene ether diamine. These polyether diprimary diamines are available commercially from Texaco Chemical Company under the trademark "JEFFAMINE". In general they are prepared by known processes for the amination of glycols. For example, they may be prepared by aminating the glycol in the presence of ammonia, Raney nickel catalyst, and hydrogen as set forth in Belgium Patent No. 634,741. Alternatively, they may be prepared by treating the glycol with ammonia and hydrogen over a nickel-copper-chromium catalyst as taught by United States Patent No. 3,654,370. Other methods for the production thereof include those taught in United States Patent Nos. 3,155,728 and 3,236,895 and French Patent Nos. 1,551,605 and 1,446,708. All of the foregoing patents are incorporated herein by reference. The tricarboxylic component may be almost any carboxylic acid anhydride containing an additional carboxylic group or the corresponding acid thereof containing two imide-forming vicinal carboxyl groups in lieu of the anhydride group. Mixtures thereof are also suitable. The additional carboxylic group must be esterifiable and preferably is substantially noni idizable. The tricarboxylic acid materials can be characterized by the following formula: 0 II / \ R'OOC-R 0 \ / II o where R is a trivalent organic radical, preferably a C 2 to C 20 aliphatic, aromatic, or cycloaliphatic trivalent organic radical and R' is preferably hydrogen or a monovalent organic radical preferably selected from.the group consisting of C λ to C 6 aliphatic or cycloaliphatic radicals and C g to C 12 aromatic radicals, e.g. phenyl; most preferably hydrogen. A preferred tricarboxylic component is trimellitic anhydride. Briefly, these polyoxyalkylene diimide diacids may be prepared by known imidization reactions including melt synthesis or by synthesizing in a solvent system. Such reactions will generally occur at temperatures of from 100 degrees C to 300 degrees C, preferably at from about 150 degrees C to about 250 degrees C while drawing off water or in a solvent system at the reflux temperature of the solvent or azeotropic (solvent) mixture. Although the weight ratio of the above ingredients is not critical, it is preferred that the diol be present in at least a molar equivalent amount, preferably a molar excess, most preferably at least 150 mole % based on the moles of dicarboxylic acid (b) and polyoxyalkylene diimide diacid (c) combined. Such molar excess of diol will allow for optimal yields, based on the amount of acids, while accounting for the loss of diol during esterification/condensation. Further, while the weight ratio of dicarboxylic acid (b) to polyoxyalkylene diimide diacid (c) is not critical to form the polyetherimide esters used in the present invention, preferred compositions are those in which the weight ratio of the polyoxyalkylene diimide diacid (c) to dicarboxylic acid (b) is from about 0.25 to about 2 , preferably from about 0.4 to about 1.4. The actual weight ratio employed will be dependent upon the specific polyoxyalkylene diimide diacid used and more importantly, the desired physical and chemical properties of the resultant polyetherimide ester. In general, the lower the ratio of polyoxyalkylene diimide diester to dicarboxylic acid the better strength, crystallization and heat distortion properties of the polymer. Alternatively, the higher the ratio, the better the flexibility, tensile set and low temperature impact characteristics. In preferred embodiments, the polyetherimide ester product will comprise the reaction product of dimethyl terephthalate, most preferably, with up to 40 mole % of another dicarboxylic acid; 1,4-butanediol, optionally with up to 40 mole % of another saturated or unsaturated aliphatic or cycloaliphatic diol; and a polyoxyalkylene diimide diacid prepared from a polyoxyalkylene diimine of molecular weight of from about 600 to about 12000, preferably from about 900 to 4000, and trimellitic anhydride. In its most preferred embodiments, the diol will be 100 mole % 1,4-butanediol and the dicarboxylic acid 100 mole % dimethyl terephthalate. The polyetherimide esters described herein may be prepared by conventional esterification/condensation reactions for the production of polyesters. Exemplary of the processes that may be practiced are as set forth in, for example, U.S. Pat. Nos. 3,023,192, 3,763,109, 3,651,014, 3,663,653 and 3,801,547, herein incorporated by reference. Additionally, these compositions may be prepared by such processes and other known processes to effect random copolymers, block copolymers or hybrids thereof wherein both random and block units are present. It is customary and preferred to uti e a catalyst in the process for the production c the polyetherimide esters of the present invention. In gex-ral, any of the known ester-interchange and polycondensation catalysts may be used. Although two separate catalysts or catalyst systems may be used, one for ester interchange and one for polycondensation, it is preferred, where appro 1 —iate, to use one catalyst or catalyst system for both. In those instances where two separate catalysts are used, it is preferred and advantageous to render the ester-interchange catalyst ineffective following the completion of the precondensation reaction by means of known catalyst inhibitors or quenchers, in particular, phosphorus compounds such as phosphoric acid, phosphenic acid, phosphonic acid and the alkyl or aryl esters of salts thereof, in order to increas the thermal stability of the resultant polymer. Exemplary of the suitable known catalysts there may be given the acetates, carboxylates, hydroxides, oxides, alcoholates or organic complex compounds of zinc, manganese, antimony, cobalt, lead, calcium and the alkali metals insofar as these compounds are soluble in the reaction mixture. Specific examples include, zinc acetate, calcium acetate and combinations thereof with antimony tri-oxide and the like. These catalysts as well as additional useful catalysts are described in U.S. Pat. Nos. 2,465,319; 2,534,023; 2,850,483; 2,892,871; 2,937,160; 2,998,412; 3,047,539; 3,110,693 and 3,385,830, among others, incorporated herein by reference. Where the reactants and reactions allow, it is preferred to use the titanium catalysts including the inorganic and organic titanium containing catalysts, such as those described in, for example, U.S. Pat. Nos. 2,720,502; 2,727,881; 2,729,619; 2,822,348; 2,906,737; 3,047,515; 3,056,817, 3,056,818; and 3,075,952 among others, incorporated herein by reference. Especially preferred are the organic titanates such as tetra-butyl titanate, tetra-isopropyl titanate and tetra-octyl titanate and the complex titanates derived from alkali or alkaline earth metal alkoxides and titanate esters, most preferably the organic titanates. These too may be used alone or in combination with other catalysts such as for example, zinc acetate, manganese acetate or antimony trioxide, and/or with a catalyst quencher as described above. Although these polyetherimide esters possess many desirable properties, it is often preferred to stabilize the compositions to heat, oxidation, radiation by UV light and the like, as described in the aforementioned U.S. Patent No. 4,556,705. The polyacrylate elastomers or rubbery alkylacrylates are generally copolymers having two major components: the backbone, comprising from about 95 to about 99 weight percent of the polymer; and the reactive cure site, comprising from about 1 to about 5 weight percent of the polymer. Preferably the copolymers have high molecular weights, typically around 100,000 Mv (viscosity average molecular weight). The backbones are made from monomeric aci esters to form repeating units of primarily two types: (CH--CH) or (CH--CH) I I C=0 C=0 I I °- C n H 2n + l °- C n 2n OC m H 2m + l where n is 2 or 4 and m is 1 or 2. The most common cure sit monomers are described in the below referenced Starmer et al. article. Especially preferred are 2-chloroethyl vinyl ethe and allyl glycidyl ether. Physically, polyacrylate elastomer are inherently soft and tacky. They commonly have relativel low Mooney viscosities (ML-1+4 @ 100° C) in the 25 to 6 range. These elastomers are more fully described in P.H. Starmer and F.R. Wolf, Encyclopedia of Polymer Science an Engineering, 2d Ed., 306-325 (1985), incorporated herein b reference. The mixing of the polyetherimide esters an polyacrylate elastomers may be carried out in any device know to those skilled in the art. Preferably the components ar melt mixed in a compounding device such as an internal mixe (Brabender or Banbury type) and extruders (twin screw o kneading) . The polyetherimide esters and polyacrylat elastomers are typically combinable in proportions rangin from about 20 to about 99 parts by weight polyetherimide este and from about 80 to about 1 part by weight polyacrylat elastomer based upon 100 parts by weight of the two resin combined. Preferably, the polyetherimide ester is present i an amount ranging from 20 to about 80 parts by weight, mos preferably from about 40 to about 60 parts by weight; an correspondingly the polyacrylate elastomer is present in a amount ranging from about 80 to about 20 parts by weight, mos preferably from about 60 to about 40 parts by weight. I another preferred embodiment the compositions of the presen invention comprise about 50 parts by weight polyetherimid ester and about 50 parts by weight polyacrylate elastomer. The mixing compositions may also contain, in addition to resin and rubber, various additives known to those skilled in the art for use in compounding of thermoplastics, rubbers, and their blends, to modify the properties thereof, such as, but not limited to fillers, stabilizers, antidegradents, processing aids, plasticizers, pigments and the like. Typical fillers would include carbon blacks, silicas, clays, minerals or mixtures threof. Both low and high molecular weight plasticizers are contemplated. In a typical composition, the thermoplastic copolyetherimide ester resin, rubber and additives are mixed in the appropriate device at a temperature high enough to soften and/or melt the materials such that an intimate mixture is obtained. Once an intimate mixture is obtained, the rubber material is cured by the addition of crosslinking agents, and optionally accelerators and heating, e.g., at from about 200° C to about 250° C, for from about 30 min. to about 30 sec, preferably from 5 min. to about 30 sec. Crosslinking agents are any agents which promote vulcanization of the acrylic elastomer. The cure system employed varies with type of cure-site monomer present in the acrylic elastomer. Preferred crosslinking agents are soaps including metallic carboxylates such as sodium or potassium stearate. Optionally the cure system may also comprise an accelerator as well as a crosslinking agent. Preferred accelerators include sulfur; sulfur donors such as tetramethylthiouram; or bases such as magnesium oxide or tertiary amines. Ammonium benzoate, ammonium adipate, and soap/quaternary amine systems are also known to be effective cure systems, as are red lead/ethylene thiourea and diamines and polyamines. Most preferred is a soap/quaternary ammonium system. These and others are more extensively discussed in the above-referenced Starmer et al. article. Mixing time is determined by the temperature and/or amounts of crosslinking agents added. The materials thus produced are processable by common thermoplastic processing techniques, such as injection and compression molding techniques and yield flexible, elasto eric parts. DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples illustrate the present invention. They are not to be construed to limit the claims in any manner whatsoever. EXAMPLES 1 AND 1A* To a Banbury mixer are added a crosslinkable polyacrylate elastomer comprising alkyl halide vinyl ether cure sites ("HYTEMP" 4451CG, Zeon Chemical Co.), a polyetherimide ester resin ("LO-MOD" J-1013, GE Plastics, Pittsfield, MA, McCready, U.S. Patent No. 4,456,705), a hindered phenolic antioxidant stabilizer ("IRGANOX 1010", CIBA-Geigy), a plasticizer ("PARAPLEX" -62, C. P. Hall Co., Chicago, IL, U.S.A.), and a phosphite/thioester secondary stabilizer ("MARK" 5117, Argus Div., Witco Co., N.Y., U.S.A.). The mixture is mixed to form an intimate blend. Once an intimate blend is obtained, a crosslinker (sodium stearate) and an accelerator (quaternary ammonium complex, "NPC-50", Zeon Chemical Co., Japan) are added. The mixture is then dynamically cured by mixing for 3 to 4 minutes at a temperature of 200 ° to 220° C. The composition is injection molded into test specimens and tested for tensile strength properties. For comparative purposes, a back-to-back sample is prepared, except that a copolyether ester resin similar to those described in EPO 0 327 010 A2 ("HYTREL" G-4078) is employed as the thermoplastic elastomerinstead of the polyetherimide ester resin. The formulations used and the physical properties obtained are set forth in Table 1. TABLE 1 Example 1A* . Ingredients(parts/wt) Polyetherimide ester resin — 763.6 Polyether ester resinb Polyacrylate elastomerc" Sodium stearate crosslinker Quaternary ammonium accelerator Hindered phenol antioxidant e Plasticizer Secondary antioxidant 9 Processing aid Properties Tensile break strength, psi Elongation break, % a~"LOMOD" J1013, GE Plastics, Pittsfield, MA 01201, U.S.A. b—"HYTREL" G-4078, DuPont Company, Wilmington, DE, U.S.A. c—"HYTEMP" 4451CG, Zeon Chemical Co., Japan d—"NPC-50", Zeon Chemical Co., Japan e—"IRGANOX"1010, CIBA-Geigy Co., Ardsley, NY, U.S.A. f—"PARAPLEX" G-62, C.P. HALL Co., Chicago, IL, U.S.A. g—"MARK" 5117, Witco Chemical Co., N.Y. U.S.A. h—"STRUKTOL" WS-280, Struktol Co., U.S.A. The foregoing results demonstrate that a composition prepared by dynamically vulcanizing a crosslinkable polyacrylate rubber with a thermoplastic copolyetherimide ester resin unexpectedly provides better retention of tensile properties than a composition prepared by dynamically vulcanizing a polyacrylate rubber with a thermoplastic copolyether ester resin, as taught in the prior art EPO 0 327 010. This is especially surprising in light of the better tensile properties of the copolyether ester alone when compared with the copolyetherimide ester alone, tensile breaking strengths being typically 2359 psi and 2159 psi, respectively, and elongations at break of 532 % and 215 %, respectively. Thus, by employing a copolyetherimide ester as the thermoplastic resin dynamically vulcanized with a crosslinkable rubbery alkylacrylate there is observed a 49.2 percent retention in tensile break strength and a 72.6 percent retention in elongation at break, as compared to a 37.7 percent retention in tensile break strength and 34.2 percent retention in elongation at break with the copolyether ester of the prior art. EXAMPLES 2-4 To a Brabender mixer are added 42.6 g of a polyacrylate elastomer (100 phr) , 28.4 g of a polyetherimide ester (66.7 phr) and 0.43 g (1 phr) of an antioxidant ("IRGANOX" 1010). The mixture is mixed and heated at 220°C to form an intimate blend. Once an intimate blend is obtained, 1.70 g (4 phr) of a crosslinker (sodium stearate) and 0.85 (2 phr) of an accelerator ("NPC-50") are added. The mixture is dynamically cured by mixing for 2 to 3 minutes at 220°C an the composition is compression molded into test specimens an tested for tensile strength properties according to AST D-412. For comparative purposes, tests are run without curing. The results along with compositional data are set forth belo in Table 2. Comparative Example Polyacrylate elastomer having alkylhalide vinyl ether cure sites (Zeon Chemicals Co.) Polyetherimide ester ("LO-MOD" J1013, General Electric Co., prepared in accordance with Exampl c 1 of McCready, U.S. Pat. No. 4,556,705) d Polyetherimide ester ("LO-MOD" JB1090, General Electric Co.) e Polyetherimide ester (General Electric Co., see footnote c) f Quaternary Ammonium Accelerator (Zeon Chemicals Co.) Sodium Stearate It can be seen from . Table 2 above tha dynamically curing the polyetherimide ester vastly improve the tensile break strength with a minimal decrease i elongation break. (Example 3 vs. 3A*) . In the copolyetherimid ester examples, curing improved the tensile break strength. EXAMPLES 5-8 The procedure of Examples 2-4 is repeated excep employing a Banbury mixer and various other additives and th concentration of a filler is varied. The compositions ar then injection molded into ASTM D-412 Type 1 bars. The result along with compositional data are set forth in Table 3 below TABLE 3 810.00 540.27 8.10 20.25 162.00 4.05 4.05 16.20 32.40 1001 105 3113 990 45.5 B/B 76 1.19 16 49 a b Polyacrylate elastomer (Zeon Chemicals Co., footnote a Table 2) Polyetherimide ester (General Electric Co., footnote b Table 2) A = failed during initial straining at 100% c B = failed during hold at 100% strain according to ASTM D395-B for 22 hours, average values of four runs EXAMPLES 9-13 . The procedure of Examples 5-8 is repeated except various othe additives are employed and two different plasticizers ar employed at two concentration levels (2.5 and 5.0 phr). Th results are set forth in Table 4 below. TABLE 4 EFFECT OF PLASTICIZER Example 10 11 12 13 Composition (g) Hytemp 4051 EP J 850.00 840.00 PEIE 566.95 560.28 Struktol WS280 8.50 8.40 Hi-Sil 243LD 85.00 84.00 Mark 5117 4.25 4.20 Irganox 1010 4.25 4.20 NPC-50 17.00 16.80 Sodium Stearate 34.00 33.60 Paraplex G-62 21.25 42.00 Plastolein 9720 21.25 42.00 TABLE 4 (continued) = Polyacrylate elastomer (Zeon Chemicals Co., footnote a Table 2) = Polyetherimide ester (General Electric Co., footnote b Table 2) A = Failed during initial straining at 100% B = Failed during hold at 100% strain c = according to ASTM D395-B for 22 hours, average values o four runs. EXAMPLES 14-18 The procedure of Examples 5-8 is repeated excep various other additives are employed and the rubber/resi weight ratio is varied at 20/80, 40/60, 50/50, 60/40 an 80/20. The results along with compositional data are set fort below in Table 5. Example Composition (g) Hytemp 4051 EP ' PEIE Struktol WS280 Paraplex G-62 Mark 5117 Irganox 1010 NPC-50 Sodium Stearate Properties Type c bars Tensile Break, psi Elongation Break, % Young's Modulus, psi 100% Modulus, psi 200% Modulus, psi Percent Strain at Yld. % Tension Set, % Example Type 1 bars Tensile Break, psi Elongation Break, % Young's Modulus, psi 100% Modulus, psi 200% Modulus, psi Percent Strain at Yld. Hardness, Shore-A b Polyacrylate elastomer (Zeon Chemical Co., footnote a Table 2) Polyetherimide ester (General Electric Co., footnote b Table 2) Scorched in mixer, crumb was compression molded into plaque for testing Die cut from 4 in. x 6 in. compression molded plaques From the above Tables 1-5 it can be seen that the physical properties of a typical composition containing 60 parts by weight rubber and 40 parts by weight crystalline thermoplastic polyetherimide ester and a suitable additives package are: Tension Set (ASTM D412) typically 15 to 25 percent; Compression Set (ASTM D395 Method B-plied sample) approximately 16 percent at 23°C/22 hours and 45 percent at 100°C/22 hours. Hardness values (Shore A durometer) of 55 to 80+ points can be achieved by suitable choice of components and additives. The compositions of the present invention are placed under Dynamic Mechanical Thermal Analysis (DMTA) to produce DMTA curves ' . Typical thermoplastic materials, such as the thermoplastic elastomers used herein, exhibit storage modulus versus temperature DMTA curves which can be described as possessing a glassy plateau which is generally constant in magnitude, followed by a glass transition region which is characterized by a two to three order of magnitude drop in the storage modulus to the so-called rubbery plateau. The rubbery plateau-storage modulus value is then usually observed to decrease with increasing temperature in thermoplastics (i.e. viscous flow) . In semi-crystalline thermoplastics the rubbery plateau is then followed by a large drop off at the crystalline melting point of the polymer. In the compositions of the present invention, the drop off of modulus associated with the melting of the polyetherimide ester is observed to be followed by what may be termed a second rubbery plateau which was found to be of essentially constant magnitude to the extent of the temperature tested (250° C) . The presence of this second rubbery plateau was found to be dependent on the ratio of rubber to thermoplastic with compositions having below 50 weight percent rubber not exhibiting the second rubbery plateau. In a thermoset rubber material, the storage modulus would be essentially constant in the rubbery plateau region and would not drop off with increasing temperature (until degradation occurs), due to crosslinking of the system. To test the thermoplastici y of the compositions a typical material which exhibits the second rubbery plateau was prepared, molded and then heated for 75 minutes at 200° C in an air circulating oven. The material is then charged into a Brabender mixer and mixed to a molten state in which the consistency was observed to be constant as a function of time over a ten minute test period. Thus, the materials are thermoplastics. If the materials were becoming thermoset above the melting point of the crystalline thermoplastic polyetherimide ester, they would have shear degraded when reprocessed as does a true thermoset material. The above patents, patent applications, publications and test methods are hereby incorporated by reference. Many variations of the present invention will suggest themselves to those skilled in the art in light of the above-detailed description. For example, any copolyetherimide ester resin and crosslinkable alkylacrylate elastomer may be employed. Other suitable crosslinkers and accelerators are also contemplated. Additives such as flame retardants, light stabilizers and the like may be employed in the compositions of the present invention. All such obvious modifications are within the full intended scope of the appended claims.

Claims: CLAIMS : 1. A thermoplastic elastomer composition comprising: (A) a polyetherimide ester copolymer; (B) a crosslinkable rubbery alkylacrylate, and (C) a crosslinking agent. 2. A thermoplastic elastomer composition as defined in Claim 1 wherein said polyetherimide ester copolymer comprises the reaction product of (a) one or more low molecular weight diols; (b) one or more dicarboxylic acids; and (c) one or more polyoxyalkylene diimide diacids. 3. A thermoplastic elastomer composition as defined in Claim 1 wherein said diol component (a) comprises from about 60 to about 100 mole percent 1,4-butanediol. 4. A thermoplastic elastomer composition as defined in Claim 2 wherein said dicarboxylic acid component (b) comprises from about 60 to about 100 mole percent dimethyl terephthalate. 5. A thermoplastic elastomer composition as defined in Claim 2 wherein said polyoxyalkylene diimide diacid component (c) is derived from one or more polyoxyalkylene diamines and one or more tricarboxylic acid compounds containing two vicinal carboxyl groups or an anhydride group and an additional carboxyl group, and is characterized by the following formula: 0 0 wherein each R is independently selected from the group consisting of C 2 to C 20 aliphatic and cycloaliphatic trivalent organic radicals and C g to C 20 aromatic trivalent organic radicals; each R' is independently selected from the group consisting of hydrogen, C χ to C 6 aliphatic and cycloaliphatic monovalent organic radicals and C s to C- 2 aromatic monovalent organic radicals; and G is the radical remaining after removal of the hydroxy groups of a long chain ether glycol having an average molecular weight of from about 600 to 12000. 6. A thermoplastic elastomer composition as defined in Claim 5 wherein said polyoxyalkylene diimide diacid is derived from trimellitic anhydride and a polyoy ilkyl diamine selected from the group consisting of polypropylene oxide diamine and a copoly(ethylene oxide-propylene oxide)diamine having predominantly polyethylene oxide in the backbone. 7. A thermoplastic elastomer composition as defined in Claim 1 wherein said rubbery alkylacrylate consists essentially of repeating units of the formulae: (CH-- CH) and (CH,- CH) I I c=o c=o I I 0C n H 2n + l O n H 2 n-°- CmH 2m + l where n is 2 or 4 and m is 1 or 2 and a cure site monomer. 8. A thermoplastic elastomer composition as defined in Claim 7 wherein said rubbery alkylacrylate is based on repeating units of the formula: (CH 2 - CH) I c=o OC 2 H 5 9. A thermoplastic elastomer composition as defined in Claim 1 wherein said crosslinking agent is selected from the group sodium stearate, potassium stearate and a mixture thereof. 10. A thermoplastic elastomer composition as defined in Claim 1 wherein said polyetherimide ester component (A) comprises from about 20 to about 99 parts by weight and said rubbery alkylacrylate component (B) comprises from about 80 to about 1 part by weight based upon 100 parts by weight of (A) and (B). 11. A thermoplastic elastomer composition as defined in Claim 10 wherein said component (A) comprises from about 20 to about 80 parts by weight and said component (B) comprises from about 80 to about 20 parts by weight. 12. A thermoplastic elastomer composition as defined in Claim 11 wherein said component (A) comprises from about 40 to about 60 parts by weight and said component (B) comprises from about 60 to about 40 parts by weight. 13. A thermoplastic elastomer composition as defined in Claim 10 wherein said component (A) comprises about 50 parts by weight and said component (B) comprises about 50 parts by weight. 14. A thermoplastic elastomer composition as defined in Claim 1 which further comprises a filler, a stabilizer, an antidegradent, a processing aid, a plasticizer, a pigment, or mixtures of any of the foregoing. 15. A thermoplastic elastomer composition as defined in Claim 14 wherein said filler is selected from the group consisting of carbon blacks, silicas, clays and minerals. 16. A thermoplastic elastomer composition as defined in Claim 14 wherein said plasticizer comprises a lo molecular weight plasticizer or a high molecular weigh plasticizer or both. 17. A thermoplastic elastomer composition as defined in Claim 1 which further comprises an accelerator. 18. A thermoplastic elastomer composition as defined in Claim 17 wherein said accelerator is selec fro the group consisting of sulfur, sulfur donors, magnesiu oxide, tertiary amines, quaternary ammonium compounds an mixtures of any of the foregoing. 19. A thermoplastic elastomer composition a defined in Claim 18 wherein the crosslinker comprises sodiu stearate and the accelerator comprises a quaternary ammoniu compound. 20. A process for producing a thermoplasti elastomer composition comprising: (I) mixing (i) a polyetherimide ester copolymer, and (ii) a crosslinkable rubbery alkylacrylate; an (II) curing the mixture obtained in step (I) by adding crosslinking agent. 21. A process as defined in Claim 20 wherein said polyetherimide ester comprises the reaction product of (a) one or more low molecular weight diols; (b) one or more dicarboxylic acids; and (c) one or more ' polyoxyalkylene diimide diacids. 22. A process as defined in Claim 21 wherein said diol component (a) comprises from about 60 to about 100 mole percent 1,4-butanediol. 23. A process as defined in Claim 21 wherein said dicarboxylic acid component (b) comprises from about 60 to about 100 mole percent dimethyl terephthalate. 24. A process as defined in Claim 21 wherein said polyoxyalkylene diimide diacid component (c) is derived from one or more polyoxyalkylene diamines and one or more tricarboxylic acid compounds containing two vicinal carboxyl groups or an anhydride group and an additional carboxyl group, and is characterized by the following formula: 0 0 wherein each R is independently selected from the group consisting of C 2 to C 20 aliphatic and cycloaliphatic trivalent organic radicals and C g to C 20 aromatic trivalent organic radicals; each R' is independently selected from the group consisting of hydrogen, C χ to ; C g aliphatic and cycloaliphatic monovalent organic radicals and C 6 to C 12 aromatic monovalent organic radicals; and G is the radical remaining after removal of the hydroxy groups of a long chain ether glycol having an average molecular weight of from about 600 to 12000. 25. A process as defined in Claim 24 wherein sai polyoxyalkylene diimide diacid .is derived from trimelliti anhydride and a polyoxyalkyl diamine selected from the grou consisting of polypropylene oxide diamine and copoly(ethylene oxide-propylene oxide)diamine havin predominantly polyethylene oxide in the backbone. 26. A process as defined in Claim 20 wherein sai rubbery alkylacrylate consists essentially of repeating unit of the formulae: (CH,- CH) and (CH,- CH) 2 I I c=o c*o I I 0 n H 2n + l OC n H 2n-°- CmH 2m + l where n is 2 or 4 and m is 1 or 2 and a cure site monomer. 27. A process as defined in Claim 26 wherein sai rubbery alkylacrylate is based on repeating units of th formula: (CH, -CH) I c=o 0C 2 H 5 28. A process as defined in Claim 20 wherein sai crosslinking agent is selected from the group sodium stearate potassium stearate and a mixture thereof. 29. A process as defined in Claim 20 wherein sai polyetherimide ester component (i) comprises from about 20.t about 99 parts by weight and said rubbery alkylacrylat component (ii) comprises from about 80 to about 1 part b weight based upon 100 parts by weight of (i) and (ii). 30. A process as defined in Claim 29 wherein sai component (i) comprises from about 20 to about 80 parts b weight and said component (ii) comprises from about 80 t about 20 parts by weight. 31. A process as defined in Claim 30 wherein said component (i) comprises from about 40.to about 60 parts by weight and said component (ii) comprises from about 60 to about 40 parts by weight. 32. A process as defined in Claim 29 wherein said component (i) comprises about 50 parts by weight and said component (ii) comprises about 50 parts by weight. 33. A process as defined in Claim 30 wherein step (I) further comprises mixing (iii) a filler, a stabilizer, an antidegradent, a processing aid, a plasticizer, a pigment, or mixtures of any of the foregoing. 34. A process as defined in.Claim 33 wherein said filler is selected from the group consisting of carbon blacks, silicas, clays and minerals. 35. A process as defined in Claim 33 wherein said plasticizer comprises a low molecular weight plasticizer or a high molecular weight plasticizer or both. 36. A process as defined in Claim 20 wherein said step (II) further comprises adding an accelerator. 37. A process as defined in Claim 36 wherein said accelerator is selected from the group consisting of sulfur, sulfur donors, magnesium oxide, tertiary amines, quaternary ammonium compounds and mixtures of any of the foregoing. 38. A process as defined in Claim 37 wherein the crosslinker comprises sodium stearate and the accelerator comprises a quaternary ammonium compound.

Inventors: HANS PAUL JOSEPH, JENKINS KENNETH EVANS, HANS, PAUL, JOSEPH, JENKINS, KENNETH, EVANS
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 1991
Main classification: C08L33
IPC codes: C08K5, C08L33, C08L79