Polyetherimide Esters

Thermoplastic copolyester adhesives are well known having been described in numerous patents including, for example U.S. Pat. Nos. 3,832,314, 932,326, 4,062,907, 4,130,603 an24,145,335. These are all based on segmented copolyetheresters having long chain ether-ester units and short chain ester units, alone or blended with a low molecular weight thermoplastic resin. Additional hot melt adhesive compositions have been prepared based on polyester amides see e.g. U.S. Pat. No. 4,254,254.

Thermoplastic polyetherester imides are known having been described in U.S. Pat. No. 4,371,692, to Wolfe, Jr., and U.S. Pat. No. 4,552,950, to McCready. The polyetherester imides described in Wolfe, Jr. are the reaction product of a diol, a polyoxyalkylene glycol and a diimide diacid which is the reaction product of a relatively low molecular weight aliphatic diamine or an aromatic diamine and trimellitic ahydride. These polymers are used as coating materials for cables, belts, and hoses. The polyetherimide esters described in McCready are the reaction product of a low molecular weight diol and a diimide diacid which is the reaction product of a relatively high molecular weight polyoxyalkylene diamine and a tricatboxylic acid having two vicinal carboxyl groups or the anhydride thereof.

The present invention is directed to thermoplastic elastomeric polyetherimide esters comprising the reaction products of (i) a diol mixture comprised of at least one low molecular weight diol and at least one high molecular weight diol, and (ii) at least one high molecular weight polyoxyalkylene diimide diacid. The polyoxyalkylene diimide diacid is comprised of the reaction products of at least one high molecular weight polyoxyalkylene diamine and at least one tricarboxylic acid having two vicinal carboxyl groups or its anhydride.

The novel polymers of the present invention comprise the reaction products of (i) a diol mixture comprised of at least one low molecular weight diol and at least one high molecular weight diol, and (ii) a polyoxyalkylene diimide diacid.

The instant polymers generally contain at least two of the recurring structural units represented by the general formulae ##STR1## wherein: each R is independently a trivalent organic radicals;

G is the radical remaining after removal of the terminal (or as nearly terminal as possible) amino groups of a long chain alkylene ether diamine;

D is the radical remaining after removal of the terminal hydroxy groups of a low molecular weight diol; and

B is the radical remaining after removal of the terminal hydroxy groups of a high molecular weight diol.

The low molecular weight diols suitable for use in preparing the compositions of the instant invention include saturated and unsaturated aliphatic and cycloaliphatic dihydroxy compounds as well as aromatic dihydroxy compounds. These diols are of a low molecular weight, i.e., having an average molecular weight of about 300 or less. 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.

Preferred saturated and unsaturated aliphatic and cycloaliphatic low molecular weight diols are those having from about 2 to about 19 carbon atoms. Exemplary of these diols there may be given ethylene glycol, propanediol, 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, and the like. Preferred are 1,4-butanediol and mixtures thereof with hexanediol, butenediol, or cyclohexane dimethanol.

Aromatic diols suitable for use herein are generally those having from 6 to about 19 carbon atoms. Included among these 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 about 8 carbons. Where more than one diol is employed, it is generally preferred that at least about 60 mole percent, based on the total diol content, be the same diol, more preferably at least 80 mole percent. Particularly useful compositions are those wherein 4-butanediol is present, either alone or in admixture with another diol such as butenediol 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 at least about 400, preferably at least about 600, and more preferably at least about 900. They may have average molecular weights as high as about 12,000, 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(alkenylene)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 the 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 amounts 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(propylene ether)glycol, and poly(ethylene ether)glycols end capped with poly(propylene ether)glycol and/or propylene oxide.

When utilizing the high molecular weight or long chain poly(alkylene ether)glycols it is generally preferred that these high molecular weight poly(alkylene ether)glycols have a carbon-to-oxygen ratio of from about 1.8 to about 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 oxide or polyethylene carbonate for poly(ethylene)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 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 at least one poly(alkylene)glycol with at least one poly(alkylene ether)glycol, and the like.

The diol mixtures of the low molecular weight diol and the high molecular weight diol generally contain from about 5 to about 70 weight percent, preferably from about 10 to about 60 weight %, and more preferably from about 15 to about 50 weight percent of at least one high molecular weight diol. Weight percent of the high molecular weight diol is calculated based on the total amounts of low molecular weight diols and high molecular weight diols present in the diol mixture.

Since the amounts of recurring structural units I and II present in the instant composition are generally related to and dependent upon the amounts of the low molecular weight diols and the high molecular weight diols present in the diol mixture, the instant compositions generally contain from about 5 to about 70 weight percent of recurring structural unit II, preferably from about 10 to about 60 weight percent, and more preferably from about 15 to about 50 weight percent. Weight percent of recurring structural unit II present in the instant compositions is calculated based on the total amounts, by weight, of structural units I and II present in the instant compositions.

Polyoxyalkylene diimide diacids 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, with a high molecular weight polyoxyalkylene diamine. These polyoxyalkylene diimide diacids and processes for their preparation are more fully described in U.S. Pat. No. 4,552,950.

In general, the polyoxyalkylene diimide diacids useful herein may be characterized by the general formula ##STR2## wherein: each R is independently a trivalent organic radical, preferably a C.sub.2 to C.sub.20 aliphatic, aromatic, or cycloaliphatic organic radical;

each R' is independently hydrogen or a monovalent organic radical preferably selected from C.sub.1 to C.sub.6 aliphatic and cycloaliphatic radicals and C.sub.6 to C.sub.12 aromatic radicals, e.g., benzyl, 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 about 600 to about 12,000, preferably from about 900 to about 4,000, and a carbon-to-oxygen ratio of from about 1.8 to about 4.3.

Representative long chain ether glycols from which the polyoxyalkylene diamine is prepared by amination 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 ethylene oxide propylene oxide, and methyltetrahydrofuran. Polyformyl glycols prepared by reacting formaldehyde with diols such as 1,4-butanediol and 1,5-pentanediol are also useful. Especially preferred poly(alkylene ether)glycols are poly(tetramethylene ether)glycol, poly(propylene ether)glycol and poly(ethylene ether)glycols end capped with poly (propylene ether)glycol and/or propylene oxide.

The poly(alkylene ether)diamines suitable for use in the preparation of the polyoxyalkylene diimide diacids of Formula III may be characterized by the formula

wherein G is as defined hereinafore. These polyether diprimary diamines are available commercially from Texaco Chemical Company under the trademark JEFFAMINE.RTM.. 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. Pat. No. 3,654,370. Other methods for their preparation include those taught in U.S. Pat. Nos. 3,155,728 and 3,236,895 and French Pat. Nos. 1,551,605 and 1,466,708. All of the foregoing patents are hereby incorporated herein by reference.

The tricarboxylic acid 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.

While trimellitic anhydride is preferred as the tricarboxylic component, any 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',3diphenyl tricarboxylic anhydride, diphenyl sulfone-3',3,4-tricarboxylic anhydride, ethylene tricarboxylic anhydride, 1,2,5-naphthalene tricarboxylic anhydride, 1,2,4-butane tricarboxylic anhydride, diphenyl isopropylidene-3,3',4-tricarboxylic anhydride, 3,4-dicarboxyphenyl-3'-carboxyl-phenyl ether anhydride, 1,3,4-cyclohexane tricarboxylic anhydride, and the like. These tricarboxylic acid materials can be characterized by the formula ##STR3## wherein R and R' are as defined hereinafore.

Briefly, the polyoxyalkylene diimide diacids of Formula III may be prepared by known imidization reactions including melt synthesis or by synthesizing in a solvent system. For example, the diimide diacid may be prepared by reacting two moles of the tricarboxylic component per mole of polyoxyalkylene diamine by refluxing at between about 100.degree. C. to 300.degree. C., preferably 150.degree. C. to 250.degree. C., in a suitable solvent such as dimethyl formamide, diethylformamide, diethylacetamide, N-methylcaprolactan, or dimethylsulfoxide, among others known to those skilled in the art, or in an azeotropic mixture of said solvent with an additional inert solvent, e.g., xylene. The solvent is subsequently removed by distillation and the residual solvent removed by vacuum drying to leave the diimide diacid. Alternately the diimide diacid may be prepared by melt synthesis wherein the tricarboxylic acid component and the diamine are heated at between 100.degree. C. to 300.degree. C., preferably 150.degree. C. to 250.degree. C., while drawing off water, for several hours to produce the diiacid.

The polymers of the instant invention can be prepared by melt condensation procedures. Typically, the procedure involves the reaction in the presence of a titanate catalyst of a polyoxyalkylene diimide diacid or an ester thereof of Formula III with the diol mixture containing the low molecular weight diol and the high molecular weight diol, the diol mixture being present in a molar excess. Initially, reaction takes place at about atmospheric pressure while the temperature is increased up to about 160.degree.-260.degree. C. while distilling off volatiles. The resulting prepolymer of relatively low molecular weight can be converted to a high molecular weight polymer by continuing the reaction at 200.degree.-260.degree. C. at reduced pressures, preferably less than 30 mm and more preferably at less than about 5 mm.

The typical procedure for the preparation of the polymers of the present invention can be varied widely. For example, as an alternative to the foregoing process, it is also possible to directly charge the reactor vessel or system with the polyoxyalkylene diimide diacid reactants rather than preform the diimide diacid of Formula III.

Specifically, when preparing the polymers of this invention by the procedure in which the diimide diacid or ester thereof is formed during the course of the melt condensation, the tricarboxylic component and the polyoxyalkylene diamine of Formula IV are charged in place of the preformed diimide diacid or its ester of Formula III along with the other ingredients including the diol mixture of low molecular weight diols and high molecular weight diols. From then on, the melt condensation is conducted in substantially the same manner as previously described. In theory, two moles of tricarboxylic component react with one mole of the diamine, however, when the diimide diacid is prepared in the presence of the diol mixture, a minor amount of tricarboxylic component 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 component to diamine. An excess of diamine reduces the degree of branching, while an excess of tricarboxylic component increases branching. Ratios of 2 moles of tricarboxylic component to 0.85-1.15 moles of diamine have been found to yield useful polymers. In addition to controlling branching by varying the tricarboxylic component/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 diimide diacid 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 will generally be less than about 0.15 mole per mole of diimide diacid or ester thereof. Useful branching agents other than trimellitic anhydride include trimethyl trimellitate, glycerol, trimethyl proane, trimesic acid and its esters, and the like.

In general, 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 used are those set forth, for example, in U.S. Pat. Nos. 3,023,192, 3,763,109, 3,651,014, 3,663,653 and 3,801,547, all of which are incorporated herein by reference.

It is customary and preferred to utilize a catalyst in the process for the production of the polyetherimide ester 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 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 trioxide and the like. These catalysts as well as additional useful catalysts are described in U.S. Pat. Nos. 2,567,319, 2,534,028, 2,892,815, 2,937,160, 2,998,412, 3,047,539, 3,110,693 and 3,385,830, all of which are incorporated herein by reference.

Where the reactants and the 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, 3,056,628 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, calcium acetate, manganese acetate or antimony trioxide, and/or with a catalyst quencher as described hereinafore. The catalyst should be present in catalytic amounts, i.e., from about 0.005 to about 2.0 percent by weight based on total reactants.

Both batch and continuous methods can be used for any stage of polymer preparation. Further polymerization of lower molecular weight polymers can also be accomplished in the solid phase by heating solid polymer particles in a vacuum or in a stream of inert gas to remove liberated low molecular weight diol.

The preparation of the polymers of this invention can be carried out in the presence of an antioxidant, as well as other stabilizers including thermal and ultraviolet radiation stabilizers. While stabilizers are not normally required on a laboratory scale, their use, particularly oxidative/and or thermal stabilizers, is generally preferred on a commercial scale.

Many of the stabilizers known in the art for polyetherimide esters may be used including 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.

Among the stabilizers which can be used are those described in U.S. Pat. No. 4,552,950, which is incorporated herein by reference.

A second embodiment of the instant invention is a thermoplastic elastomeric polyetherimide ester composition comprising the reaction products of at least one high molecular weight diol and at least one high molecular weight polyoxyalkylene diimide diacid. The high molecular weight diols and the high molecular weight polyoxyalkylene diimide diacids are the same as those described hereinafore. The polymer of this embodiment contains at least one recurring structural unit represented by Formula II wherein B and G are as described hereinafore.

The method for preparing the polyetherimide esters of this embodiment is substantially the same as described hereinafore except that rather than using the diol mixture of a low molecular weight diol and a high molecular weight diol as one of the reactants a high molecular weight diol or mixtures of two or more different high molecular weight diols are utilized.

In the reaction of the high molecular weight diol with the high molecular weight polyoxyalkylene diimide diacid the high molecular weight diol may generally be present in equimolar amounts or in a molar excess.

The thermoplastic elastomeric polyetherimide esters of the instant invention are useful as hot melt adhesives. They exhibit better or improved adhesive properties at low temperatures than conventional polyetherimide esters comprised of the reaction products of a low molecular weight diol and a high molecular weight polyoxyalkylene diimide diacid.

In order to more fully and clearly illustrate the present invention the following examples are set forth. It is intended that these examples be considered as illustrative rather than limiting the invention as disclosed and claimed herein. In the examples all parts and percentages are on a weight basis unless otherwise indicated.

The following examples illustrate the polymers of the instant invention.

This example illustrates a polyetherimide ester derived from a long chain polyalkylene ether diimide diacid, a low molecular weight diol, and a high molecular weight diol.

Into a reactor vessel there are placed 16.52 parts by weight of butanediol, 480.8 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with Jeffamine D2000, a propylene ether diamine having an average molecular weight of about 2,000), 16.52 parts by weight of a poly(ethylene glycol) (available from Aldrich Chemical Co. and having an average molecular weight of about 1,000), and a titanium catalyst. The mixture is heated to about 1800.degree. C. whereupon water is generated. After an hour the pot temperature is increased to about 240.degree. C., vacuum applied, and after a total of 3 hours reaction time the polyetherimide ester product is cooled and a tacky polymer is obtained.

The viscosity was measured at 100.degree. C. and determined to be 520 centipoise. The Infrared Spectrum was obtained and was 2968 cm.sup.-1, 1776 cm.sup.-1, 1714 cm.sup.1, 1370 cm.sup.-1, and 1100 cm.sup.-1.

This example illustrates a polyetherimide ester derived from a long chain polyalkylene ether diimide diacid and a high molecular weight diol.

Into a reactor vessel are placed 200 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with Jeffamine D2000, a polypropylene ether diamine having an average molecular weight of about 2,000), 84.4 parts by weight of a poly(ethylene glycol) available from Aldrich Chemical Co. and having an average molecular weight of about 1,000, and a titanium catalyst. The mixture is heated to about 180.degree. C. whereupon water is generated. After an hour the pot temperature is increased to about 240.degree. C., vacuum applied, and after a total of 3 hours reaction time the polyetherimide ester product is cooled and a tacky polymer obtained.

The viscosity of this polyetherimide ester was measured at 100.degree. C. and determined to be 1550 centipoise. The Infrared Spectrum was obtained and was 2969 cm.sup.-1, 1777 cm.sup.-1, 1717 cm.sup.-1, 1375 cm.sup.- and 1100 cm.sup.-1.

This example illustrates a polyetherimide ester derived from a long chain polyalkylene ether diimide diacid and a high molecular weight diol.

Into a reactor vessel are placed 200 parts by weight of a polyoxyalkylene diimide diacid (prepared by the imidization of trimellitic anhydride with Jeffamine D2000, a propylene ether diamine having an average molecular weight of about 2,000), 84.4 parts by weight of a poly(propylene oxide) glycol (available from Aldrich Chemical Co. and having an average molecular weight of about 1,000) and a titanium catalyst. The mixture is heated to about 180.degree. C. whereupon water is generated. After an hour the pot temperature is increased to about 240.degree. C., vacuum applied, and after a total of 3 hours reaction time the polyetherimide ester product is cooled and a tacky polymer is obtained.

The viscosity of this polyetherimide ester product is measured at 100.degree. C. and determined to be 470 centipoise. The Infrared Spectrum was obtained and was 2969 cm.sup.-1, 1777 cm.sup.-1, 1717 cm.sup.-1, 1375 cm.sup.-1, and 1100 cm.sup.-1.

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 described which are within the full intended scope of the invention as defined by the appended claims.