MODIFIED THERMOPLASTIC COPOLYETHERIMIDE ESTER ELASTOMERS

Abstract: Novel modified polyetherimide esters are prepared from diols, dicarboxylic acids and a combination of polyoxyalkylene diimide diacidsand dimer acid. These compositions have many excellent properties which make them particularly useful for extrusion and molding applications.

Description: The present invention relates to novel, modified thermoplastic copolyetherimide ester elastomers having a high melting point with an improved crystallization rate and increased flexibility as well as improved solvent resistance than unmodified compositions. Polyetherester imides are well known having been described in numerous publications and patents including for example, Honore et al, "Synthesis and Study of Various Reactive Oligmers and of Poly(ester-imide-ether)s, European Polymer Journal Vol. 16, pp. 909-916, October 12, 1979; and in Kluiber et al, U.S. Patent No. 3,274,159 and Wolfe Jr., U.S. Patent Nos. 4,371,692 and 4,371,693, respectively. While the foregoing polyetherimide ester elastomers have excellent physical properties, they are more susceptible to thermal and oxidative degradation as well as attack by solvents as a consequence of the presence of high amounts of various high molecular weight polyethers in the copolymer. However, the presence of the high molecular weight polyether is vital in order to manifest the physical properties, particularly the low flexural modulus, of such elastomeric compositions. It is an object of the present invention to provide copoly etherimide esters which have improved thermal and oxidative stability without a loss in other physical properties. It is also an object of the present invention to provide copolyetherimide esters having improved solvent resistance without sacrificing the superior flexibility of the polyetherimide ester. Finally, it is an object of the present invention to provide copolyetherimide esters having a high melting point and improved crystallization rates combined with excellent flexibility. It has now been discovered that modified copolyetherimide esters having improved thermal and oxidative stability, solvent resistance and crystallization and flexibility characteristics can be prepared by conventional processes from a) one or more C₂ - C₁₅ aliphatic and/or cycloaliphatic diols, b) one or more dicarboxylic acids selected from phthalic, terephthalic and isophthalic acid and ester derivatives thereof and c) a combination of i) a certain polyoxyalkylene diimide diacid and ii) a certain dimer acid wherein the dimer acid is present in an amount of from 5 to 40, preferably to about 30 weight percent based on the combined weight of (i) and (ii). Components i) and ii) are more fully defined below. The specific amounts of i) polyoxyalkylene diimide diacid and ii) dimer acid employed in the practice of the present invention is generally dependent upon the desired properties of the resultant polyetherimide ester. In general, the weight ratio of (c) the combination of i) polyoxyalkylene diimide diacid and ii) dimer acid to dicarboxylic acid (b) is from 0.25 to 2.0, preferably from 0.4 to 1.4. Finally, the compositions may contain and preferably do contain additional stabilizers for even greater stabilization and low temperature impact strength. Suitable diols (a) for use in preparing the compositions of the present invention preferably have a molecular weight of about 250 or less. When used herein, the term "diols" and "lower 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. Especially preferred diols are 1,4-butanediol and mixtures thereof with hexanediol or butenediol, most preferably 1,4-butanediol. The third component to be used in the practice of the present invention is a combination (c) of i) polyoxyalkylene diimide diacid and ii) dimer acid wherein the amount of dimer acid present is from 5 to 40 weight percent, preferably from 15 to 30 weight percent, based on the combined weight of (i) and (ii). Polyoxyalkylene diimide diacids (i) suitable for use herein are high molecular weight diimide diacids wherein the average molecular weight is greater than 700, most preferably greater than 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. In general, the polyoxyalkylene diimide diacids useful herein may be characterized by the following formula: wherein each R is selected from trivalent C₂ to C₂₀ aliphatic and cycloaliphatic radicals and trivalent C₆ to C₂₀ aromatic radicals; each R' is independently hydrogen or a monovalent organic radical selected from the group consisting of C₁ to C₆ aliphatic and cycloaliphatic radicals and C₆ to C₁₂ aromatic radicals, e.g. benzyl, most preferably hydrogen; and G is the radical remaining after the removal of the terminal (or as nearly terminal as possible) amino groups of a long chain alkylene ether diamine having an average molecular weight of from 600 to 12000, preferably from 900 to 4000, and a carbon-to-oxygen ratio of from 1.8 to 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 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 and/or propylene oxide. In general, the polyoxyalkylene diamines useful within the scope of the present invention will have an average molecular of from 600 to 12000, preferably from 900 to 4000. The tricarboxylic component may be almost any conventional 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 nonimidizable. Further, while trimellitic anhydride is preferred as the tricarboxylic component, any of a number of suitable tricarboxylic acid constituents will occur to those skilled in the art including 2,6,7 naphthalene tricarboxylic anhydride; 3,3',4 diphenyl tricarboxylic anhydride; 3,3',4 benzophenone tricarboxylic anhydride; 1,3,4 cyclopentane tricarboxylic anhydride; 2,2',3 diphenyl tricarboxylic anhydride; diphenyl sulfone - 3,3',4 tricarboxylic anhydride, ethylene tricarboxylic anhydride; 1,2,5 napthalene tricarboxylic anhydride; 1,2,4 butane tricarboxylic anhydride; diphenyl isopropylidene 3,3',4 tricarboxylic anhydride; 3,4 dicarboxyphenyl 3'-carboxylphenyl ether anhydride; 1,3,4 cyclohexane tricarboxylic anhydride; etc. These tricarboxylic acid materials can be characterized by the following formula: where R and R' are as defined above. 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°C. to 300°C., preferably at from 150°C. to 250°C. while drawing off water or in a solvent system at the reflux temperature of the solvent or azeotropic (solvent) mixture. Dimer acids (ii) useful in the preparation of the copolyetherimide esters of the present invention are themselves prepared by the dimerization of unsaturated fatty acids of 18 carbons. Exemplary of fatty acids from which they are prepared there may be given oleic acid, linoleic acid and linolenic acid. The preparation and structure of dimer acid is described in Journal of the American Oil Chemists Society, 39, 534-545 (1962), Journal of the American Chemical Society 66, 84 (1944) and U.S. Patent No. 2,347,562, Suitable dimer acid may be employed in its unhydrogenated or hydrogenated form and includes the acid functioning derivatives thereof. Several grades of dimer acid are available commercially which vary in monomer and trimer content. Inclusive of suitable commercial dimer acids there may be given those available from Emery Industries under the tradenames EMPOL 1010 (a hydrogenated dimer acid) and EMPOL 1014. EMPOL 1010 is reported as typically containing 97% dimer acid, 3% trimer acid and essentially no monobasic acid and extremely low unsaturation, whereas EMPOL 1014 is typified as containing 95%, 4% and 1% of dimer, trimer and monobasic acids respectively. Also available are the dimer acids sold under the tradename HYSTRENE from the Humko Products Division of Witco Chemical Corporation, especially HYSTRENE 3695 which typically contain 95% dimer acid and a weight ratio of dimer to trimer of 36:1. Preferred grades are substantially free of such monomer and trimer fractions, most preferably less than 5% by weight, and are fully saturated, or substantially so. Where desirable, the dimer acid member may be substantially freed of monomer and trimer fractions by molecular distillation or other suitable means. In general, the dimer acid exists in the copolyetherimide ester as a soft or rubbery segment and accordingly dimer acids of relatively high molecular weight (preferably greater than 500) are preferred so that the copolyetherimide esters are resilient, but do not deform until relatively high temperatures are reached. Applicant has now found that novel copolyetherimide esters may be prepared having high melting temperatures, faster crystallization rates and greater flexibility than unmodified copolyetherimide esters by incorporating therein dimer acid. Specifically, applicants have found that copolyetherimide esters having comparable levels of polyoxyalkylene diimide diacid incorporated therein have less flexibility, resilience and impact properties, including, for example, low temperature impact. Alternatively, unmodified composition having essentially the same flexibility properties, resilience and so forth suffer from greater susceptability to oxidative and thermal degradation as well as manifest poorer solvent resistance, as a consequence of the higher levels of polyether component in the polymer. Thus by the practice of applicant's invention one is able to achieve compositions of greater flexibility, crystallization rate solvent, resistance and thermal and oxidative stability. In general, the benefits of the present invention can be achieved by incorporating into the copolyetherimide ester from 5 to 40 weight percent, preferably from 15 to 30 weight percent, based on the combined weight of dimer acid and polyoxyalkylene diimide diacid of dimer acid. 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 the combination (c) of i) polyoxyalkylene diimide diacid and ii) dimer acid, 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. In general, the lower the ratio of the combination (c) of (i) polyoxyalkene diimide diacid (ii) and dimer acid to dicarboxylic acid the better the 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 its preferred embodiments, the compositions of the present invention will comprise the reaction product of dimethylterephthalate,optionally with up to 40 mole % of another dicarboxylic acid; 1,4-butanediol, optionally with up to 40 mole % of another saturated or unsaturated aliphatic and/or cycloaliphatic diol; and a combination of i) a polyoxyalkylene diimide diacid prepared from a polyoxyalkylene diamine of molecular weight of from 600 to 12000, preferably from 900 to 4000 and trimellitic anhydride and ii) dimer acid in an amount of from 10 to 40% by weight, most preferably from 15 to 30% by weight based on the combined weight of (i) and (ii). In its most preferred embodiments, the diol will be 100 mole % 1,4-butanediol and the dicarboxylic acid 100 mole % dimethylterephthalate. The novel 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. 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 utilize a catalyst in the process for the production of the polyetherimide esters of the present invention. In general, 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 appropriate, 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 or salts thereof, in order to increase 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. These catalysts as well as additional useful catalysts are described in U.S. Patent Nos. 2,465,319; 2,534,028; 2,850,483; 2,892,815; 2,937,160; 2,998,412; 3,047,539; 3,110,693 and 3,385,830. 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, 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. 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 the novel polyetherimide ester of the present invention possess many desirable properties, including improved stability as compared to unmodified polymers, it may be preferred to further enhance stabilization of these compositions to heat, oxidation and radiation by UV light. This can be accomplished by incorporating stabilizer materials into the compositions either during production or while in a hot melt stage following polymerization. The particular stabilizers useful herein are any of those known in the art which are suitable for polyetherimide esters. Satisfactory stabilizers comprise phenols and their derivatives, amines and their derivatives, compounds containing both hydroxyl and amine groups, hydroxyazines, oximes, polymeric phenolic esters and salts of multivalent metals in which the metal is in its lower valence state. Representative phenol derivatives useful as stabilizers include the 3,5-di-tert-butyl-4-hydroxy hydrocinnamic triester with 1,3,5-tris-(2-hydroxyethyl)-s-triazine-2,4,6-(1H,3H,5H)trione; 4,4'-bis(2,6-ditertiary-butylphenol); 1,3,5-trimethyl-2,4,6-tris(3,5-ditertiary-butyl-4-hydroxybenzyl)benzene and 4,4'-butylidene-bis(6-tertiary-butyl-m-cresol). Various inorganic metal salts or hydroxides can be used as well as organic complexes such as nickel dibutyl dithiocarbonate, manganous salicylate and copper 3-phenyl-salicylate. Typical amine stabilizers include N,N'-bis(betanaphthyl)-p-phenylene diamine; N,N'-bis(1-methyl-heptyl) -p-phenylene diamine and either phenyl-betanaphthyl amine or its reaction products with aldehydes. Mixtures of hindered phenols with esters of thiodipropionic acid, mercaptides and phosphite esters are particularly useful. Additional stabilization to ultraviolet light can be obtained by compounding with various UV absorbers such as substituted benzophenones and/or benzotriazoles. Optionally, it may be desirable to add a minor amount, up to 20 mole %, preferably up to 10 mole %, based on the moles of the polyoxyalkylene diimide diacid, of a tricarboxylic component to the reaction mixture. While higher amounts of the tricarboxylic component may be used, this has the disadvantage of reducing some of the beneficial properties of the present polymers. Suitable tricarboxylic components are the same as identified above for the preparation of the polyoxyalkylene diimide diacid. While it is preferred that the additional tricarboxylic component be the same as used in the preparation of the polyoxyalkylene diimide diacid, it is not necessary. The addition of the tricarboxylic acid com ponent will have the added benefit of picking up and reacting with any residual, unreacted amine groups and, consequently, aiding in the viscosity build of the polymer itself. Further, the properties of these polyesters can be modified by incorporation of various conventional inorganic fillers such as carbon black, silica gel, alumina, clays and chopped fiberglass. These may be incorporated in amounts up to 50% by weight, preferably up to 30% by weight. In general, these additives have the effect of increasing the modulus of the material at various elongations. The following examples are presented as illustrative of the present invention and are not to be construed as limiting thereof. Physical properties were determined according the proper ASTM methods as follows: Flexural Modulus ASTM D 790 Tensile Elongation ASTM D 638 Shore D Hardness ASTM D 2240 In general, all compositions were prepared by placing all reactants in the reaction vessel and heating to 180°C. After the theoretical amount of methanol was removed, the pot temperature was increased to about 250°C. and a vacuum applied 133Pa( 1mm Hg) until the desired viscosity polymer was obtained. All reactions, unless otherwise specified were catalyzed with tetraoctyl titanate catalyst. Diimide Diacid A A polyoxyalkylene diimide diacid was prepared by the imidization of trimellitic anhydride with Texaco Chemical Company's Jeffamine® D2000, a polypropylene ether diamine, average molecular weight 2000, Diimide Diacid B A second polyoxyalkylene diimide diacid was prepared by the imidization of trimellitic anhydride with Texaco Chemical Company's Jeffamine ED-900, a predominately polyethylene oxide backbone, copoly(ethylene oxide-propylene oxide) diamine, average molecular weight 900. EXAMPLES E1-E4, COMPARATIVE EXAMPLES CE1-CE6 A series of examples were prepared typifying the modified copolyetherimide esters of the present invention and unmodified copolyetherimide esters. In addition to demonstrating the benefits attributed to these compositions, these examples demonstrate the broad application of the present teaching giving examples with different amounts of dimer, varying weight ratio of i) polyoxyalkylene diimide diacids and ii) dimer to dicarboxylic acid (b) and various polyoxyalkylene diimide diacids. The specific compositions of each example and comparative example as well as the physical properties thereof are set forth in Table 1. All components are expressed in parts by weight unless otherwise stated. From the examples in Table 1 it is clear that the compositions of the present invention have improved flexibility at the same or about the same levels of incoporation of polyoxyalkylene diimide diacid. For example comparison of Example E1, E3 and E4 with comparative Examples CE1, CE3 and CE4 respectively demonstrates the improved flexibility of the composition of the present invention. Alternatively, unmodified compositions having about the same flexibility as the modified polyetherimide ester compositions of the present invention require about a 20% increase in the amount of polyoxyalkylene diimide diacid component. Because of the susceptability of the polyether component to thermal and oxidative degradation as well as attack by solvents, applicant's composition by virtue of lesser amounts of polyether will have enchanced thermal and oxidative stability as well as improved solvent resistance as compared to the unmodified compositions.

Claims: A polyetherimide ester comprising the reaction product of a) one or more C₂ to C₁₅ aliphatic or cycloaliphatic diols, b) one or more dicarboxylic acids selected from phthalic, terephthalic and isophthalic acid and ester derivatives thereof, c) i) one or more polyoxyalkylene diimide diacids of the formula: wherein R is selected from trivalent C₂ to C₂₀ aliphatic and cycloalyphatic radicals and trivalent C₆ to C₂₀ aromatic radicals; R' is selected from hydrogen, C₁ to C₆ aliphatic and cycloaliphatic radicals and C₆ to C₁₂ aromatic radicals, and G is the radical remaining after the removal of the amino groups of an alkylene ether diamine having an average molecular weight of 600 to 12,000, and ii) one or more dimer acids selected from dimerized unsaturated C₁₈ fatty acids, the hydrogenated derivatives thereof and the acid-functional derivatives of either, the amount of the dimer acid being from 5 to 40% of the total weight of component c)i and c)ii). The polyetherimide ester of claim 1 wherein the amount of dimer acid is from 15 to 30 percent by weight based on the combined weight of (i) and (ii). The polyetherimide ester of claim 2 wherein the dimer acid is hydrogenated. The polyetherimide ester of claim 3 wherein the dimer acid is at least 95% by weight hydrogenated dimer acid. The polyetherimide ester of claim 1 wherein the diol component (a) is from about 60 to 100 mole % 1,4-butanediol. The polyetherimide ester of claim 5 wherein the diol component (a) is from about 80 to 100 mole % 1,4-butanediol. The polyetherimide ester of claim 1 wherein the dicarboxylic acid component (b) is from about 60 to 100 mole % dimethyl terephthalate. The polyetherimide ester of claim 1 wherein the dicarboxylic acid component (b) is from about 80 to 100 mole % dimethyl terephthalate. The polyetherimide ester of claim 1 wherein the polyoxyalkylene diimide diacid component (i) is derived from one or more polyoxyalkylene diamines and one or more tri carboxylic acid compounds containing two vicinal carboxyl groups or an anhydride group and an additional esterifiable carboxyl group, and is characterized by the following formula: wherein R, R' and G are as defined in claim 1. The polyetherimide ester of claim 9 wherein each R is a C₆ trivalent aromatic radical, each R' is hydrogen and G is the radical remaining after removal of the amino groups of an alkylene ether diamine having an average molecular weight of 900 to 4000. The polyetherimide ester of claim 1 wherein the weight ratio of (c) to dicarboxylic acid (b) is from 0.25 to 2. The polyetherimide ester of claim 11, wherein the weight ratio of (c) to dicarboxylic acid (b) is from 0.4 to 1.4.

Inventors: MCCREADY, RUSSELL JAMES
Applicants: GENERAL ELECTRIC COMPANY
Application year: 1985
Main classification: C08G73
IPC codes: C08G63, C08G73