THERMOPLASTIC POLYETHERIMIDE ESTER POLYMERS EXHIBITING IMPROVED FLEXIBILITY

Abstract: A polyetherimide ester polymer comprised of the reaction products of: (i) a diol component comprising at least one low molecular weight diol and at least one high molecular weight diol; (ii) at least one dicarboxylic acid or an ester forming reactive derivative thereof; and (ii) a set of reactants selected from (a) (1) at least one high molecular weight poly(oxy alkylene)diamine, and (2) at least one tricarboxylic acid or its derivative, or (b) at least one high molecular weight polyoxyalkylene diimide diacid. The polymer of this invention exhibits improved flexibility; and the diol component (i) contains an amount of high molecular weight diol at least effective to improve the flexibility of the polymer.

Description: Poly(etherimide ester) polymers comprised of the reaction products of (a) a low molecular weight diol, (b) a dicarboxylic acid, (c) a poly(oxy alkylene)diamine, and (d) a tricarboxylic acid or its derivatives are known and are described in U.S.-A-4,544,734 and 4,556,705 and in U.S.-A-4,556,688. These poly(etherimide ester) polymers exhibit excellent stress-strain properties, low tensile set, high melting temperatures and/or excellent stength/toughness characteristics as well as good flexibility which are especially suitable for molding and extrusion applications. It has now been discovered that poly(etherimide ester)polymers can be provided which exhibit lower flexural modulus and better flexibility than conventional presently available poly(etherimide ester) polymers. These poly(etherimide ester)polymers exhibiting these improved flexural properties are obtained by the utilization of a diol component which is comprised of a mixture of at least one low molecular weight diol and at least one high molecular weight diol. In accordance with the instant invention there are provided polyetherimide ester polymers exhibiting improved flexibility. The polymers of the instant invention are defined in claim 1. The present invention is directed to polyetherimide ester polymers exhibiting improved or exceptionally good flexural properties. The polyetherimide esters of the instant invention, while exhibiting improved flexibility, also exhibit, to a substantial degree, substantially most of the other advantageous properties of conventional polyetherimide ester polymers derived from low molecular weight diols. The polymers of the present invention are comprised of the reaction products of: (a) a diol component comprised of at least one low molecular weight diol and at least one high molecular weight diol; (b) at least one dicarboxylic acid or an ester forming reactive derivative thereof; (c) at least one high molecular weight poly (oxy alkylene)diamine; and (d) at least one tricarboxylic acid or its derivative. The low molecular weight diols which form one part of the diol component (a) and which are suitable for use in preparing the polymers of the present invention include the saturated and unsaturated aliphatic and cycloaliphatic dihydroxy compounds as well as the aromatic dihydroxy compounds. These diols are of a low molecular weight, i.e., having an average molecular weight of less than 250. When used herein the term "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 derivative. 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. Exemplary of preferred saturated and unsaturated aliphatic and cycloaliphatic low molecular weight diols there may be given ethylene glycol, propanediol, 1,4-butanediol, pentanediol, 2-methyl propanediol, 2,2-dimethyl propanediol, hexanediol, decanediol, 1,2 - cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, butenediol, hexenediol. Preferred are 1,4-butanediol and mixtures thereof with hexanediol, butenediol, or cyclohexane dimethanol. Included among low molecular weight 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 low molecular weight 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 8 carbon atoms. Where more than one diol is employed, it is generally preferred that at least 60 mole percent, based on the total low molecular weight diol content, be the same low molecular weight diol, more preferably at least 80 mole percent. Particularly useful compositions are those wherein the low molecular weight diol is 1,4-butanediol, either alone or in admixture with another low molecular weight diol such as butenediol, hexanediol, or cyclohexane dimethanol. The high molecular weight diols which comprise the second component of the diol mixture of the present invention are those having an average molecular weight of 400 to 12000, preferably at least about 600, and more preferably at least about 900. The highest average molecular weight is preferably 10,000, and more preferably about 4,000. The high molecular weight diols suitable for use in the practice of the instant invention include the saturated and unsaturated aliphatic and cycloaliphatic dihydroxy compounds, preferably the saturated and unsaturated aliphatic dihydroxy compounds. The saturated and unsaturated aliphatic dihydroxy compounds include the poly(alkylene) glycols, the poly(alkyenylene)glycols, and the poly(oxy alkylene)glycols (the polyether glycols). Some illustrative non-limiting examples of the high molecular weight poly(alkylene)glycols include fully hydrogenated poly(butadiene)glycol, poly (ethylene)glycol, poly(propylene)glycol, and poly (tetramethylene)glycol. Some illustrative non-limiting examples of poly(alkenylene) glycols include poly(butadiene)glycol and partially hydrogenated poly(butadiene)glycol. Some illustrative non-limiting examples of the poly(oxy alkylene) glycols 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 amount of a second monomer such as ethylene oxide, propylene oxide, and methyl tetrahydrofuran. Especially preferred poly(alkylene ether)glycols are poly(tetramethylene ether)glycol, poly(ethylene ether)glycol, pol(propylene ether)glycol, and poly(ethylene ether) glycols end-capped with poly(propylene ether)glycol and/or propylene oxide. The high molecular weight or long chain poly(alkylene ether)glycols have a carbon-to-oxygen ratio of from 1.8 to 4.3. When used herein the term "high 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 the ester forming derivatives of the long chain or high molecular weight diols there may be given the acetates of the diols as well as, for example, polyethylene carbonate for polyethylene glycol. Mixtures of these high molecular weight diols as well as individual long chain diols may be used in the practice of the present invention. Mixtures of these high molecular weight diols are meant to include mixtures of two or more different high molecular weight diols, e.g., a mixture of two or more different poly(alkylene)glycols, a mixture of two or more different poly(alkenylene)glycols, a mixture of two or more different poly(alkylene ether) glycols, a mixture of a poly(alkylene ether)glycol with a poly(alkylene)glycol. The diol component (a) contains an amount of at least one high molecular weight diol which is effective to improve or increase the flexibility of the polyetherimide ester polymer, i.e., an amount effective to lower the flexural modulus of the polyetherimide ester polymer. This amount is at least 3 weight percent, preferably at least 5 weight percent, and more preferably at least 10 weight percent. An amount of about 75 weight percent of high molecular weight diol should not be exceeded, preferably an amount of about 60 weight percent, and more preferably an amount of about 50 weight percent. In general, if less than 3 weight percent of the high molecular weight diol is present there will be no appreciable improvement in the flexibility of the polymer. If more than 75 weight percent of the high molecular weight diol is present the flexural modulus of the polymer will generally be too low for successful injection molding of the polymer. Weight percent of the high molecular weight diol is calculated based on the total amounts, by weight, of the low molecular weight diol and the high molecular weight diol present in the diol component (a). 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 of a low molecular weight, i.e., having a molecular weight of less than 300. The term "dicarboxylic acids", as it is used herein, is meant to include the equivalents of dicarboxylic acids having two functional carboxylic groups which preform substantially like carboxylic 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 mentioned above, pertains to the acid and not to its equivalent ester or ester-forming derivative. Thus, an ester of a dicarboxylic acid having a molecular weight greater than 300 or an acid equivalent of a dicarboxylic acid having a molecular weight greater than 300 are included provided the acid has a molecular weight below 300. Additionally, the dicarboxylic acids may contain any substituent group(s) or combinations which do not substantially interfere with the polymer formation and use of the polymer of this invention. 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 carboxy 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 functional 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 -O- or -SO₂-. Representative aliphatic and cycloaliphatic acids which can be used for this invention are 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; dimer acid; 4-cyclohexene-1,2- dicarboxylic acid; 2-ethylsuberic acid; tetramethylsuccinic acid; cyclopentanedicarboxylic acid; decahydro-1,5 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, sebacic acid, dimer acid, glutaric acid, azelaic acid and adipic acid. Representative aromatic dicarboxylic acids which can be used include terephthalic, phthalic and isophthalic acids, bi-benzoic acid, substituted dicarboxy compounds with two benzene nuclei such as bis(p-carboxphenyl) methane, oxybis(benzoic acid), ethylene-1,2-bis-(p-oxybenzoic acid), 1,5 napththalene 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 C₁-C₁₂ 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 acid with an aliphatic and/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 dimethylterephthalate is the predominant dicarboxylic acid, most preferably when dimethylterephthalate is the only dicarboxylic acid. The polyoxylalkylene diamines (c) suitable for use in the present invention may be characterized by the following formula: H₂N-G-NH₂ 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 Pat. No. 634,741. Alternately, they may be prepared by treating the glycol with ammonia and hydrogen over a Nickel-Copper-Chromium catalyst as taught by U.S.-A-3,654,370. Other methods for the production thereof include those taught in U.S.-A-3,155,728 and 3,236,895 and FR-A-1,551,605 and 1,466,708. The long chain ether diamines suitable for use herein are polymeric diamines having terminal (or as nearly terminal as possible) amine groups and an average molecular weight of from 600 to 12,000, preferably from 900 to 4,000. Additionally, the long chain ether diamines will generally have a carbon-to-oxygen ratio of from 1.8 to 4.3:1. Representative long chain ether diamines are the poly(alkylene ether) diamines including poly(ethylene ether) diamine, poly(propylene ether) diamine, poly(tetramethylene ether) diamine; random or block copolymers of ethylene oxide and propylene oxide including propylene oxide and poly(propylene oxide) terminated poly(ethylene ether) diamine; and aminated random or block copolymers of tetrahydrofuran with minor amounts of a second monomer such as ethylene oxide, propylene oxide, and methyl tetrahydrofuran (used in proportions such that the carbon-to-oxygen mole ratio in the diamine does not exceed about 4.3 to 1). Polyformyl diamines prepared by reacting formaldehyde with diols such as 1,4-butanediol and 1,5-pentanediol and subsequently aminating are useful. Especially preferred poly(alkylene ether) diamines are poly(propylene ether) diamine, poly (tetramethylene ether) diamine, and the poly(ethylene ether) glycols which are end capped with poly (propylene ether) and/or propylene oxide and subsequently aminated. The polyoxyalkylene diamines useful within the scope of the instant invention have an average molecular weight of from 600 to 12,000, preferably from 900 to 4,000. The tricarboxylic acid (anhydride) (d) is either a 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. While trimellitic anhydride is preferred as the tricarboxylic acid component, a number of suitable tricarboxylic acid constituents can be used including 2,6,7-napthalene tricarboxylic anhydride, 3,3', 4-diphenyl tricarboxylic anhydride, 3,3',5-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-naphthalene tricarboxylic anhydride, 1,2,4-butane tricarboxylic anhydride, and 1,3,4-cyclohexane tricarboxylic anhydride. These tricarboxylic acid materials are represented by the formula wherein: R is a trivalent C₂-C₂₀ aliphatic or cycloaliphatic, or trivalent C₆-C₂₀ aromatic organic radical; and R′ is preferably hydrogen or a monovalent organic radical selected from C₁-C₆ aliphatic or cycloaliphatic radicals and C₆-C₁₂ aromatic radicals, e.g., benzyl; most preferably R′ is hydrogen. The amount by which each of the foregoing reactants is employed in the preparation of the polymers of the instant invention is not, in general critical, and depends, in part, upon the desired properties of the resultant polymer. Obviously, sufficient amounts of the diol mixture versus the dicarboxylic acid, and tricarboxylic acid versus diamine must be present, as recognized in the art, to allow for substantially complete polymerization. In general, the amount of the diol component (a) employed will be a molar equivalent or a molar excess, preferably about 1.5 molar equivalents, based on the combined molar equivalents of dicarboxylic acid (b) and the total moles of tricarboxylic (d). The amount of tricarboxylic acid (d) employed will preferably be about two molar equivalents based on the number of moles of the poly(oxy alkylene)diamine (c). Obviously, less than two molar equivalents would result in incomplete imidization of the diamine resulting in potentially poorer properties. Conversely, greater than two molar equivalents of the tricarboxylic acid (d) may lead to cross-linking and branching of the polymer. Generally, mole ratios of 2 moles of tricarboxylic acid (d) to 0.85 to 1.15 moles of poly (oxy alkylene)diamine (c) yield useful polymers. The amount by which the diamine (c) and the dicarboxylic acid (b) are used is such that the weight ratio of the theoretical amount of polyoxyalkylene diimide diacid formable from the diamine (c) and the tricarboxylic acid (d) to the dicarboxylic acid (b) is from 0.05 to 2.0, preferably from 0.4 to 1.4. As described in U.S.-A-4,556,688, the lower the ratio of the polyoxyalkylene diimide diacid 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. By the use of the diol mixture of the present invention polyetherimide ester polymers exhibiting better flexibility, i.e., lower flexural modulus, are obtained while keeping the weight ratio of the polyoxyalkylene diimide diacid to dicarboxylic acid within the aforedescribed limits. That is to say, for identical weight ratios of polyoxyalkylene diimide diacid to dicarboxylic acid polymers exhibiting better flexibility are obtained by using the instant diol mixtures than by using the low molecular weight diol alone. This general type of one-pot reaction involving the reactions of (a) a diol, (b) a dicarboxylic acid, (c) a poly(oxy alkylene)diamine, and (d) a tricarboxylic acid is described in U.S.-A-4, 556,688. The instant polyetherimide esters may also be prepared by a two-pot synthesis involving the reaction of (a) the diol mixture of a low molecular weight diol and a high molecular weight diol, (b) the dicarboxylic acid, and (e) a preformed polyoxyalkylene diimide diacid. Such a general two-pot synthesis is described in U.S.-A-4,566,705. Basically, in this process the poly(oxy alkylene) diamine (c) is first reacted with the tricarboxylic acid (d) to form a polyoxyalkylene diimide diacid (e), and said diimide diacid is then reacted with the diol mixture (a) and the dicarboxylic acid (b) to form the polyetherimide ester polymer. The polyoxyalkylene diimide diacid (e) is be represented by the formula wherein G, R, and R′ are as defined hereinafore. The polyoxyalkylene diimide diacids of Formula III suitable for use herein are high molecalar weight diimide diacids wherein their average molecular weight is greater than 700, more preferably greater than 900. They may be prepared by the imidization reaction involving a tricarboxylic acid containing two vicinal carboxyl groups or an anhydride group and an additional carboxyl group which must be esterifiable with a high molecular weight poly(oxy alkylene)diamine (c). These polyoxyalkylene diimide diacids and processes for their preparation are disclosed in U.S.-A-4,556,705. 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 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. In this two-pot process, as in the one-pot process, the amounts of the above reactants utilized is generally not critical. However, it is generally preferred that the diol mixture (a) be present in at least a molar equivalent amount, preferably a molar excess, and more preferably at least about 150 mole % based on the moles of dicarboxylic acid (b) and polyoxyalkylene diimide diacid (e) combined. Such molar excess of diol will allow for optimum yields, based on the amount of acids, while accounting for the loss of diol during esterification/condensation. It is also preferred, as mentioned hereinafore, that the weight ratio of the polyoxyalkylene diimide diacid (e) to dicarboxylic acid (b) be from 0.05 to 2.0, preferably from 0.4 to 1.4. It is likewise possible, as described in U.S.-A-4,556,688, to prepolymerize the aromatic dicarboxylic acid (b) and the diol mixture (a) to form a prepolyester. Forming the prepolyester of (a) and (b) can be achieved by conventional esterification techniques as described in U.S.-A-2,465, 319; 3,047,439 and 2,910,466. This prepolyester can then be reacted with the diimide diacid (e) and the diol mixture (a) to form the polyetherimide ester containing ester segments of the prepolyester. In its preferred embodiments, the polymer of the present invention will comprise the reaction products of dimethylterephthalate, optionally with up to about 40 mole percent of another dicarboxylic acid; a mixture of high molecular weight diol and low molecular weight diol, preferably butanediol or a mixture of butanediol with cyclohexane dimethanol or butenediol; and either (1) a high molecular weight poly(oxy alkylene)diamine and trimellitic anhydride, or (2) a high molecular weight polyoxyalkylene diimide diacid derived from trimellitic anhydride and a high molecular weight poly(oxy alkylene)diamine. Since in the practice of the present invention the diol component is a mixture of a low molecular weight diol and a high molecular weight diol, structural units IV and V are in general comprised of two sub-units, i.e., one wherein R¹ is the residue of a low molecular weight diol and one wherein R¹ is the residue of the high molecular weight diol. Thus, the polyetherimide esters of the instant invention generally contain at least the following four recurring structural units: wherein G, R and R² are as defined hereinafore, R 1' is the residue of the low molecular weight diol having a molecular weight of less than 250 absent the two hydroxyl groups, and R 1'' is the residue of the high molecular weight diol having a molecular weight of 400 to 12,000 absent the two hydroxy groups. Since, in the instant invention, the amount of the high molecular weight diol present in the diol mixture (a) is from 3 to 75 weight percent, and since the amount of units of Formulae IVb and Vb is related to the amount of the high molecular weight diol present, the combined or total amount of units of Formulae IVb and Vb present is from 3 to 75 weight percent, based on the total amounts, in weight, of units IVa, IVb, Va and Vb present. It is to be understood that under certain circumstances, particularly when utilizing processes other than the one-pot process described above, polyetherimide esters of the instant invention can be produced which are comprised of less than all four of the recurring structural units IVa-Vb, but in no case less than two recurring structural units of either Formulae IVa and Vb or Formulae IVb and Va. Thus, for example, if the polyalkyleneether diimide ester, i.e., IV, is first prepolymerized separately (by the reaction of the diol, poly(oxy alkylene) diamine, and the tricarboxylic acid) utilizing only one diol of the diol mixture, e.g., a low molecular weight diol, and the polyester, i.e., V, is then polymerized utilizing the diol mixture of the high molecular weight diol and the low molecular weight diol, then the polymer of the present invention will comprise three recurring structural units IVa, Va and Vb. Conversely, if the polyester V is first prepolymerized separately (by the reaction of the dicarboxylic acid and the diol) using only one diol of the diol mixture, e.g., the low molecular weight diol, and the polyalkyleneether diimide ester IV is then polymerized using the diol mixture of the low molecular weight diol and the high molecular weight diol, then the polyetherimide ester of the present invention will contain the three recurring structural units IVa, IVb and Va. In the process of the present invention for the preparation of the polyetherimide ester polymers, particularly where all the reactants are charged to the reactor together, i.e., the one-pot process, or where the polyoxyalkylene diimide diacid is preformed and excess tricarboxylic acid is present, a minor amount of tricarboxylic acid or anhydride may react with the available hydroxyl groups and ultimately function as a branching agent in the finished polymer. Within limits, the degree of branching in the finished polymer can be controlled by varying the mole ratio of tricarboxylic acid (d) to the poly(oxy alkylene)diamine (c). An excess of diamine reduces the degree of branching, while an excess of the tricarboxylic acid increases branching. In addition to controlling branching by varying the tricarboxylic acid/diamine mole ratio, one can compensate for branching by introducing a monofunctional reactant such as benzoic acid in minor amounts. With reference to branching it should be noted that polymers of this invention, when prepared from preformed diimid diacids, are substantially free of branching. If branching is desired, one needs only to introduce a branching agent such as trimellitic anhydride along with the preformed diimide diacid. The amount of branching agent generally will be less than 0.15 mole per mole of diimide diacid. Useful branching agents other than trimellitic anhydride include, but are not limited to, trimethyl trimellitate, glycerol, trimethylol propane, trimesic acid and its esters. Additionally, while not required, it is customary and preferred to utilize a catalyst or catalyst system 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 polymer. Exemplary of 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 anitmony tri-oxide and the like. These catalysts, as well as additional useful catalysts are described in U.S.-A-2,465,319; 2,534,028; 2,850,483; 2,892,815; 2,937,160; 2,998,412; 3,047,549; 3,110,693 and 3,385,830 among others. Where the reactants and reaction conditions allow it is preferred to use the titanium catalysts including the inorganic and organic titanium containing catalysts, such as those described, for example, in U.S.-A-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 organic titanates. These too may be used alone or in combination with other catalysts such as for example, zinc acetate, calcium acetate, magnesium acetate or antimony trioxide, and/or with a catalyst quencher as described above. The catalyst should be used in catalytic amounts, i.e., from 0.005 to 2.0 weight percent based on total reactants. Both batch and continuous methods can be used for any stage of the ether imide ester polymer preparation. Polycondensation of the polyester prepolymer with the polyoxyalkylene diimide diacid can also be accomplished in the solid phase by heating finely divided solid polyester prepolymer with the diimide diacid in a vacuum or in a stream of inert gas to remove liberated low molecular weight diol. This method has the advantage of reducing degradation because it must be used at temperatures below the softening point of the prepolymer. The major disadvantage is the long time required to reach a given degree of polymerization. Although the copolyetherimide esters of this invention possess good resistance toward heat aging and photodegradation, it is advisable to stabilize these compounds by the addition of an antioxidant. Many of the oxidative and/or thermal stabilizers known in the art for copolyesters may be used in the practice of the present invention. These may be incorporated into the composition either during polymerization or while in a hot melt stage following polymerization. Satisfactory stabilizers include the 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. Some specific examples of these stabilizers are described in U.S.-A-4,556,688. The instant compositions can be stabilized against ultraviolet radiation by the addition thereto of the well known ultraviolet radiation absorbers or stabilizers such as, for example, benzophenone derivatives, benzotriazole derivatives, cyanoacrylates, and the like. Further, the properties of these polymers can be modified by incorporation of various conventional and well known fillers such as carbon black, silica gel, alumina, clays, talc, and chopped fiberglass or glass particles. These may optionally be incorporated in amounts up to 50% by weight, preferably up to about 30% by weight. The polymers of the instant invention may also contain the various and well known flame retardants such as, for example, the halogen and/or sulfur containing organic and inorganic compounds. DESCRIPTION OF THE PREFERRED EMBODIMENT The following examples are presented to more fully illustrate the present invention. In the examples all parts and percentages are on a weight basis unless otherwise indicated. The following examples illustrate polyetherimide esters falling outside the scope of the instant invention as they do not contain any high molecular weight diol. They are presented for comparative purposes only. COMPARATIVE EXAMPLE 1 Into a reactor vessel are placed 10.5 parts by weight of butanediol, 9.5 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D-2000, a propylene ether diamine having an average molecular weight of 2,000, available from Texaco Chemical Co.), 13.5 parts by weight of dimethyl terephthalate, a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180° C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is increased to about 250°C. and a vacuum applied to produce the polyetherimide ester polymer. The Flexural Modulus (test method ASTM D790), Flexural Strength (test method ASTM D790), and Tensile Elongation (test method ASTM D638) of this polymer are determined and the results are set forth in Table I. COMPARATIVE EXAMPLE 2 This example also illustrates a polyetherimide ester polymer derived from only a low molecular weight diol. However, in this example a lower weight ratio of the diimide diacid to the dicarboxylic acid is used than in Example 1. Into a reactor vessel are placed 300 parts by weight of butanediol, 38 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 388 parts by weight of dimethyl terephthalate, a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is raised to about 250°C. and a vacuum applied to produce the polyetherimide ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table II. The following examples illustrate the polymers of the instant invention. EXAMPLE 3 This example illustrates a polyetherimide ester derived from a low molecular weight diol and a high molecular weight poly(ethylene oxide)glycol. Into a reactor vessel are placed 185 parts by weight of butanediol, 168 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 240 parts by weight of dimethyl terephthalate, 36 parts by weight of poly(ethylene oxide)glycol (average molecular weight of about 1,000), a phenolic antioxidant, and a titanium catalyst. The reaction mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is increased to about 250°C. and a vacuum applied to produce the polyetherimide ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table I. EXAMPLE 4 This example illustrates a polyetherimide ester derived from a low molecular weight diol and a high molecular weight poly(tetramethylene oxide) glycol. Into a reactor vessel there are placed 185 parts by weight of butanediol, 168 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 240 parts by weight of dimethyl terephthalate, 36 parts by weight of poly(tetramethylene oxide) glycol (average molecular weight of about 2,000), a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is increased to about 250°C. and a vacuum applied to produce the polyetherimde ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table I. EXAMPLE 5 This example illustrates a polyetherimide ester derived from a low molecular weight diol and a high molecular weight poly(tetramethylene oxide)glycol. Into a reactor vessel are placed 185 parts by weight of butanediol, 168 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 240 parts by weight of dimethyl terephthalate, 36 parts by weight of poly(tetramethylene oxide) glycol (average molecular weight of about 1,000), a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is increased to about 250°C. and a vacuum applied to produce the polyetherimide ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table I. EXAMPLE 6 This example illustrates a polyetherimide ester derived from a low molecular weight diol and a high molecular weight poly(butadiene)diol. Into a reactor vessel are placed 185 parts by weight of butanediol, 168 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 240 parts by weight of dimethyl terephthalate, 54 parts by weight of poly(butadiene)diol (average molecular weight of about 2,800; 20% vinyl, 20% cis-1,4, 60% trans-1,4), a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is raised to about 240°C. and a vacuum applied to produce the polyetherimide ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table I. EXAMPLE 7 This example illustrates a polyetherimide ester derived from a low molecular weight diol and a high molecular weight poly(butadiene)diol. Furthermore, the weight ratio of the diimide diacid to the dicarboxylic acid used in this example is the same as in comparative Example 2. Into a reactor vessel are placed 185 parts by weight of butanediol, 24 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with JEFFAMINE® D2000), 240 parts by weight of dimethyl terephthalate, 36 parts by weight of poly(butadiene)diol (average molecular weight 2,800; 20% vinyl, 20% cis-1,4, 60% trans-1,4), a phenolic antioxidant, and a titanium catalyst. The mixture is heated to about 180°C. whereupon methanol is generated. After the theoretical amount of methanol is removed the pot temperature is increased to about 240°C. and a vacuum applied to produce the polyetherimide ester polymer. The properties of this polymer are determined in accordance with the procedure of Example 1 and the results are set forth in Table II. Example No. Flexural Modulus N/mm² (psi) Flexural Strength N/mm² (psi) Tensile Elongation (%) 1 168 (24,000) 10,5 (1,500) 160 3 126 (18,000) 7,7 (1,100) 630 4 126 (18,000) 7,7 (1,100) 670 5 112 (16,000) 7 (1,000) 590 6 126 (18,000) 8,4 (1,200) 200 Example No. Flexural Modulus N/mm² (psi) Flexural Strength N/mm² (psi) Tensile Elongation (%) 2 1.400 (200,000) 55,3 (7,900) 250 7 910 (130,000) 37,8 (5,400) 10 As illustrated by the data in Tables I and II the polymers of the instant invention (Examples 3-7) have better flexibility (lower Flexural Modulus and lower Flexural Strength) than the conventional polyetherimide esters (Example 1 and 2). Generally, the lower the weight ratio of the diimide diacid to the dicarboxylic acid in the reaction mixture used to prepare the polyetherimide ester the higher the flexural modulus (the poorer the flexibility); conversely, the higher this weight ratio the lower the flexural modulus (the better the flexibility). Thus the polymer of Example 2, which has a lower weight ratio of diimide diacid to dicarboxylic acid, would be expected to have a higher flexural modulus and Flexural Strength than the polymer of Example 1 which has a higher weight ratio of diimide diacid to dicarboxylic acid. Likewise, the polymer of Example 7, since it has a lower diimide diacid to dicarboxylic acid weight ratio, would be expected to have a higher Flexural Modulus and Flexural Strength than the polymers of Examples 3-6 which have higher diimide diacid to dicarboxylic acid weight ratios. Comparing Examples 3-7 with Example 1, and Example 7 with Example 2, it is clear that the polymers of the instant invention exhibit improved, i.e., better, flexibility than the conventional polyetherimide ester polymers which are derived from only a low molecular weight diol. This improvement in flexibility occurs at different weight ratios of diimide diacid to dicarboxylic acids (Table I and Table II). A preferred embodiment of the instant invention is one wherein the polyetherimide ester polymers are free of dimer acids, particularly high molecular weight dimer acids, either as one of the reactants utilized in the preparation of the insatnt polymers, or as an added component of the instant polymers. The instant polymers are useful in the preparation of extruded or molded articles. Obviously, other modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that changes may be made in the particular embodiments of the invention as described hereinafore which are within the full intended scope of this invention as defined by the appended claims.

Claims: A polyetherimide ester comprising at least the following four recurring structural units wherein G is the residue of a poly(alkylene ether)diamine having an average molecular weight of from 600 to 12,000 and a carbon/oxygen ratio of 1.8 to 4.3:1; R is a trivalent C₂-C₂₀ aliphatic or cycloaliphatic radical or a C₆-C₂₀ aromatic radical; R² is the residue of an aliphatic, cycloaliphatic, or aromatic dicarboxylic acid having a molecular weight of less than 300 absent the two carboxyl groups; and R¹ represents the residues of at least two diols absent the hydroxyl groups, namely, R 1'' a high molecular weight diol having a molecular weight of 400 to 12,000 and R 1' a low molecular weight diol having a molecular weight of less than 250; the amount of the residue of said high molecular weight diol being from 3 to 75 weight % of R¹. The polymer of claim 1 wherein R¹ contains at least 5 weight percent of the residue of at least one high molecular weight diol. The polymer of claim 1 wherein R¹ contains at least 10 weight percent of the residue of at least one high molecular weight diol. The polymer of claim 1 wherein said high molecular weight diol has an average molecular weight of at least 600. The polymer of claim 1 wherein said high molecular weight diol has an average molecular weight of at least 900. The polymer of claim 1 wherein said high molecular weight diol is selected from aliphatic diols. The polymer of claim 6 wherein said aliphatic diols are selected from saturated and unsaturated aliphatic diols. The polymer of claim 7 wherein said high molecular weight diol is selected from unsaturated diols. The polymer of claim 8 wherein said high molecular weight diol is poly(butadiene)glycol. The polymer of claim 1 wherein said high molecular weight diol is selected from poly (oxy alkylene)glycols. The polymer of claim 10 wherein said high molecular weight diol is selected from poly(ethylene ether)glycols, poly(propylene ether) glycols, poly(tetramethylene ether)glycols, copoly(propylene ether - ethylene ether) glycols, or mixtures thereof. The polymer of claim 1 wherein said low molecular weight diol is selected from butanediol, hexanediol, butenediol, cyclohexane dimethanol, or mixtures thereof. The polymer of claim 1 wherein said dicarboxylic acid residue is derived from dimethylterephthalate.

Inventors: MCCREADY, RUSSELL JAMES, TYRELL, JOHN ALFRED
Applicants: GENERAL ELECTRIC COMPANY
Application year: 1987
Main classification: C08G73
IPC codes: C08G73, C08G63