CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority upon United States provisional application serial no. 60/057,617, filed September 4, 1997, the contents of which are herein incorporated in their entirety by this reference.

FIELD OF THE INVENTION The present invention relates to a method for increasing the molecular weight of a polymer composition by solid state polymerizing a composition composed of a polymer having at least one isocyanate reactive group and a thermoplastic polyurethane.

BACKGROUND OF THE INVENTION There is a growing need for producing high molecular weight polymers. In particular, high molecular weight polyesters and copolyesters can be used in a number of different applications. For example, high molecular weight polyesters can be used as reinforcing agents in rubber articles. Additionally, high molecular weight polyesters can be extruded and molded into a wide variety of useful articles. A problem associated with the production of high molecular weight polyesters is the amount of time it takes to produce a polymer with the desired molecular weight. Upon extended. heating, the polymer can undergo thermal degradation, which ultimately reduces the molecular weight of the polymer.

One approach for increasing the molecular weight of a polymer involves the addition of a compound that is capable of reacting with the polymer. This is referred

to in the art as "chain extension." U.S. Patent No. 4,071,503 to Thomas et al. discloses the reaction between a polycarbodiimide and a polyester in order to increase the molecular weight and melt strength. U.S. Patent No. 4,568,720 to Aharoni et al. and Jacques et al. (Polymer, Vol. 37, No. 7, pp 1189-1200, 1996) disclose the use of phosphite compounds as chain extenders. Cardi et al. (J. Applied Polsner Science, Vol. 50, pp 1501-1509, 1993) discloses the chain extension of poly(ethylene terephthalate) with 2,2'-bis(2-oxazoline). U.S. Patent No. 4,857,603 to Akkapeddi er al. discloses the chain extension of poly(ethylene terephthalate) with polylactams. <BR> <BR> <BR> <BR> <BR> <P>Bikiaris et al. (Jourszal or ofPolymer Science: Part A: Polymer Chemistry, Vol. 34, 1337- 1342, 1996) investigated the combination of diimidodiepoxides with poly(ethylene terephthalate) and poly(butylene terephthalate) in order to increase the molecular weight of the polyester. None of these references, however, disclose the use of a thermoplastic polyurethane as a chain extender.

One technique disclosed in the art for producing high molecular weight polymers is called solid state polymerization. Solid state polymerization generally involves heating a polymer at an elevated temperature below the melting point of the polymer. One advantage of solid state polymerization is that there is no handling of a high molecular weight, high viscosity molten polymer. Thermal degradation is also reduced during solid state polymerization. The process of solid state polymerization is disclosed in U.S. Patent Nos. 4,064,112 and 4,792,573, which are incorporated by reference in their entirety.

The solid state polymerization of a polymer in combination with other compounds is known in the art. U.S. Patent No. 3,853,821 to Sid-Ahmed ci al. discloses the solid state polymerization of polyesters in the presence of a diisocyanate.

International Patent Application No. WO 92/17522 to Ghisolfi discloses the solid state upgrading of a polyester resin to produce high molecular weight polyester resins.

Upgrading agents used in Ghisolfi include the dianhydrides of aliphatic and cycloaliphatic tetracarboxylic acids and tetrahydrofuran acids; and aromatic or aliphatic

diisocyanates or polyisocyanates. These processes are not attractive because of the difficulty of handling and using isocyanates, which are hazardous and toxic. These references also do not disclose the use of a thermoplastic polyurethane as a chain extender during solid state polymerization.

The prior art discloses the combination of polyurethanes and polymers in order to increase the mechanical properties of the resultant blend. U.S. Patent No. 5,519,094 to Tseng et al. and U.S. Patent No. 5,258 ,445 to Sperk et al. disclose the combination of a thermoplastic polyurethane, a polyester, and a glass fiber to produce a molding composition. International Patent No. WO 95/26432 to Wagner et al. disclose the preparation of an abrasion resistant polyester blend composed of a thermoplastic polyester, a thermoplastic polyurethane, and optionally, nonpolymeric additives that exhibits improved processing safety. Canadian Patent No. 1,111,984 (hereafter CA '111) discloses a poly(butylene terephthalate)/polyurethane molding composition.

Tseng et al., Sperk et al., Wagner et al., and CA '111 teach one of ordinary skill in the art to use a higher amounts of polyurethane in order to increase or enhance the mechanical properties of the blend. These references are not concemed with increasing the molecular weight of a polymer. Moreover, these references do not disclose the solid state polymerization of a thermoplastic polyurethane and a polymer with at least one isocyanate reactive group.

In light of the above it would be very desirable to have a method for producing a high molecular weight polymer. Moreover, it would be advantageous to reduce the time required to solid state polymerize the polymer while producing the high molecular weight polymer.

SUMMARY OF THE INVENTION In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method for making a

polymer composition, comprising solid state polymerizing a composition comprising a polymer having at least one isocyanate reactive group and a thermoplastic polyurethane.

The invention further relates to a polymer composition produced by the present invention.

The invention further relates to an article comprising the polymer composition produced by the present invention.

Additional advantages ofthe invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the Examples included therein.

Before the present methods are disclosed and described, it is to be understood that this invention is not limited to specific synthetic methods or to particular formulations, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings: The singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the descnption includes instances where said event or circumstance occurs and instances where it does not.

The term "isocyanate reactive group" is any group that can react with an isocyanate moiety as shown in Equation I. Examples of isocyanate reactive groups include, but are not limited to a hydroxyl group, an amino group, or a carboxyl group.

A "carbonyl compound" is any carboxylic acid, ester, acid halide, or anhydride.

The term "dicarbonyl compound" is any dicarboxylic acid, diester, diacid halide, or dianhydride.

The term "glycol" is any compound that possesses at least two hydroxyl groups.

Additionally, a glycol can be any precursor compound that is readily converted to a compound possessing two hydroxyl groups. An example of such a compound is hydroquinone (I), which can be converted to biphenol (II) using techniques known in the art.

In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method for making a polymer composition, comprising solid state polymerizing a composition comprising a polymer having at least one isocyanate reactive group and a thermoplastic polyurethane.

The polymer used in the present invention has at least one isocyanate reactive group. The role of the isocyanate reactive group with respect to producing a polymer composition will be discussed below. In one embodiment, the polymer comprises a polyester, a liquid crystalline polymer, a polyamide, or a combination thereof.

In one embodiment, the polymer comprises a polyester. Polyesters useful in the present invention comprise the reaction product between (1) at least one first glycol component comprising an aliphatic glycol, a cycloaliphatic glycol, an aromatic glycol, or a combination thereof, and (2) at least one first dicarbonyl component comprising an aliphatic dicarbonyl compound, a cycloaliphatic dicarbonyl compound, an aromatic dicarbonyl compound, or a combination thereof.

In one embodiment, the first glycol component comprises a first glycol compound comprising ethylene glycol; propylene glycol; 1 ,3-propanediol; 1,4- butanediol; 1,6-hexanediol; 8-octanediol; 1,1 0-decanediol; 2,2-dimethyl- 1,3- propanediol; 1,4-cyclohexanedimethanol; diethylene glycol; polyethylene glycol; polypropylene glycol; polytetramethylene glycol, or a combination thereof. In one embodiment, the first glycol compound comprises ethylene glycol; 1,3-propanediol; 1 ,4-butanediol, or 1 ,4-cyclohexanedimethanol. In another embodiment, the first glycol compound has from 2 to 10 carbon atoms. In another embodiment, the first glycol component further comprises a second glycol compound, wherein the second glycol compound comprises glycerol, trimethyolpropane, pentaerythritol, or a combination thereof. In this embodiment, the second glycol component behaves as a branching agent, which formes branches off the polymer backbone.

Examples of first dicarbonyl compounds that can react with the glycol component to produce the polyester include, but are not limited to, terephthalic acid, isophthalic acid, naphthalenedicarboxyl ic acid, cyclohexanedicarboxylic acid, or a combination thereof. In one embodiment, the first dicarbonyl component comprises terephthalic acid, cyclohexanedicarboxylic acid, or naphthalenedicarboxylic acid. Any of the isomers of naphthalenedicarboxylic acid and cyclohexanedicarboxylic acid are useful in the present invention. For example, the cis-, trans-, or cisltrans isomers of cyclohexanedicarboxylic acid can be used. In one embodiment, the 2,6-isomer of naphthalenedicarboxylic acid can be used.

In another embodiment, the polyester further comprises the reaction product of a second dicarbonyl compound comprising a CA to CAO dicarbonyl compound. The second dicarbonyl is a modifying dibasic acid. In one embodiment, the second dicarbonyl compound comprises succinic acid, glutaric acid, adipic acid, sebacic acid, dimer acid, or a combination thereof Dimer acid comprises the dimerization product of unsaturated fatty acids, wherein the fatty acid has from 14 to 24 carbon atoms. In one embodiment, the first dicarbonyl component comprises at most 65 mole % of the

second dicarbonyl compound, wherein the sum of the dicarbonyl compounds of the first dicarbonyl component equals 100 mole %.

In another embodiment, the first dicarbonyl component further comprises a third dicarbonyl compound, wherein the third dicarbonyl compound comprises trimellitic acid, trimellitic anhydride, pyromellitic anhydride, or a combination thereof. The third dcarbonyl compound can also behave as a branching agent as described above.

In one embodiment, the first dicarbonyl component comprises at least 40 mole % of the first dicarbonyl compound, wherein the sum of the dicarbonyl compounds of the first dicarbonyl component equals 100 mole %.

In one embodiment, the polyester has an inherent viscosity of from 0.2 to 1.5 dL/g, preferably from 0.3 to 1.2 dL/g as determined in 60/40 phenolitetrachloroethane.

Examples of polyesters useful in the present invention include, but are not limited to, poly(butylene terephthalate), poly(propylene terephthalate), poly(ethylene terephthalate), poly(ethylene naphthalate), poly(cyclohexanedimethylene terephthalate), or a combination thereof. In one embodiment, the polyester is poly(ethylene-2,6- naphthalate) or poly(l ,4-cyclohexanedimethylene terephthalate). In a preferred embodiment, the polyester comprises poly(butylene terephthalate) or poly(ethylene terephthalate).

In another embodiment, the polymer comprises a liquid crystalline polymer.

Any of the liquid crystalline polymers disclosed in U.S. Patent Nos. 4,169,933 and 4,161,470 are useful in the present invention, and are hereby incorporated by reference in their entirety.

In one embodiment, the liquid crystalline polymer comprises the reaction product between a second glycol component and a first carbonyl component. In one embodiment, the second glycol component comprises hydroquinone, biphenol,

cyclohexanedimethanol, or a combination thereof. In one embodiment, the first carbonyl component comprises p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, p- acyloxybenzoic acid, 2,6-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, or a combination thereof, preferably p-hydroxybenzoic acid, 2,6- naphthalenedicarboxylic acid, or terephthalic acid. In one embodiment, the liquid crystalline polyester has a molecular weight of from 5,000 to 25,000.

In another embodiment, the polymer comprises a polyamide. Any polyamide disclosed in the art can be used in the present invention. In one embodiment, the polyamide comprises the reaction product between a diamine and a second dicarbonyl component. In one embodiment, the diamine comprises a branched or straight chain aliphatic diamine, an aromatic diamine, or a cycloaliphatic diamine. In one embodiment, the diamine comprises H2N(CH2)nNH2> wherein n is from 2 to 16. In one embodiment, the diamine comprises ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,4- cyclohexanedimethylamine, 2-methyl-l ,5-pentamethylenediamine, or a combination thereof. In one embodiment, the second dicarbonyl component comprises a compound having the formula HO2C-Y-CO2H or the salt or ester thereof, wherein Y has at least two carbon atoms. In another embodiment, the second dicarbonyl component comprises sebacic acid, octadecanedioic acid, suberic acid, azelaic acid, undecanedioic acid, glutaric acid, pimelic acid, adipic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, or a combination thereof.

In one embodiment, the second dicarbonyl component comprises adipic acid.

In another embodiment, the polyamide comprises the self-condensation product of an amino carboxylic acid. In one embodiment, the amino carboxylic acid has from 2 to 16 carbon atoms between the amino group and the carboxylic acid group. In one embodiment, the amino carboxylic acid comprises 3-amino benzoic acid, 4-amino benzoic acid, or a combination thereof.

Any lactam known in the art can be used in the present invention. In one embodiment, the polyamide comprises the self-condensation product of a lactam. In one embodiment, the lactam comprises t:-aminocaproic acid, butyrolactam, pivalactam, caprolactam, capryllactam, enantholactam, undecolactam, dodecanolactam, or a combination thereof. In one embodiment, the lactårn comprises caprolactam.

In one embodiment, the polyamide comprises the self-condensation product of caprolactam (NYLON 6; the reaction product between adipic acid and hexamethylenediamine (NYLON 66); or the reaction product between adipic acid and tetramethylenediamine (NYLON 4,6. In another embodiment, the polyamide comprises a polyphthalamide.

Any thermoplastic polyurethane known in the art is useful in the present invention. Examples of thermoplastic polyurethanes than can be used in the present invention are disclosed in U.S. Patent Nos. 4,822,827; 4,376,834, and 4,567,236, which are incorporated by reference in their entirety. The thermoplastic polyurethanes of the present invention can be both rigid and elastomeric.

In one embodiment, the thermoplastic polyurethane comprises the reaction product between a polyisocyanate and a diol component. Examples of polyisocyanates include, but are not limited to, a methylenebis(phenyl isocyanate), a cycloaliphatic diisocyanate, a cyclohexylene diisocyanate, or a combination thereof. In one embodiment, any of the 4,4'-isomer, the 2,4'-isomer, or combinations thereof of methylenebis(phenyl isocyanate) can be used. Examples of other methylencbis(phcnyl isocyanates) include, but are not limited to, m- and p-phenylene diisocyanates; chlorophenylene diisocyanates; a, a'-xylylene diisocyanate; 2,4- and 2,6-toluene diisocyanate and mixtures of these latter two isomers; toluidine diisocyanate, hexamethylene diisocyanate; 1,5-naphthalene dii socyanate, or isophorone diisocyanate.

In one embodiment, the methylenebis(cyclohexyl isocyanate) is the 4,4'-isomer, the 2,4'-isomer and mixtures thereof. Any of the geometric isomers including transltrans dshrans, cis/cis and mixtures thereof can be used. Examples of cycloaliphatic diisocyanates include, but are not limited to, cyclohexylene diisocyanates (1,2-; 1,3-; or 1,4-), 1-methyl-2,5-cyclohexylene diisocyanate, 1 -methyl-2,4-cyclohexylene diisocyanate, 1-methyl-2,6-cyclohexylene diisocyanate, 4,4'-isopropylidenebis(cyclohexyl isocyanate), or 4,4'-diisocyanatodicyclohexyl.

In another embodiment, the isocyanate is a modified form of methylenebis(phenyl isocyanate). These isocyanates have been reacted with an aliphatic glycol or a mixture of aliphatic glycols, such as described in U.S. Pat. Nos.

3,394,164: 3,644,457; 3,883,571; 4,031,026; 4,115,429; 4,118,411; and 4,299,347, which are hereby incorporated by reference in their entirety.

In one embodiment, the diol component comprises at least one cycloaliphatic diol and at least one diol extender. In one embodiment, the cycloaliphatic diol comprises 1,3-cyclobutanediol; 1 ,3-cyclopentanediol; 1 ,2-cyclohexanediol; 1 ,3-cyclohexanediol; 1 ,4-cyclohexanediol, 2-cyclohexene- 1 4-diol; 2-methyl-1,4-cyclohexanediol; 2-ethyl-I 4-cyclohexanediol; 1,3 -cycloheptanediol; 1 ,4-cycloheptanediol; Zmethyl-l ,4-cycloheptanediol; 4-methyl- 1,3 -cycloheptanediol; 1,3-cyclooctanediol; 1 ,4-cyclooctanediol; 1,5-cyclooctanediol, 5-methyl-1,4-cyclooctanediol; 5-ethyl-1,4-cyclooctanediol: 5-propyl-1,4-cyclooctanediol; 5-butyl-1,4-cyclooctanediol; 5-hexyl- 1 ,4-cyclooctanediol; 5-heptyl- 1 ,4-cyclooctanediol; 5-octyl-1 ,4-cyclooctanediol; 4,4'-methylenebis(cyclohexanol); 4,4'-methylenebis(2-methylcyclohexanol); 4,4'-methylenebis(3 -methylcyclohexanol) ; 3,3 '-methylenebis(cyclohexanol); 4,4'-ethylenebis(cyclohexano 1); 4,4'-propylenebis(cyclohexanol); 4,4'-butylenebis(cyclohexanol); 4,4'-isopropylidenebis(cyclohexanol); 4,4'-isobutylenebis(cyclohexanol); 4,4'-dihydroxydicyclohexyl; 4,4'-carbonylbis(cyclohexanol);

3,3'-carbonylbis(cyclohexanol); 4,4'-sulfonylbis(cyclohexano 1), 4,4'-oxybis(cyclohexanol), or a combination thereof.

In one embodiment, the diol extender comprises ethylene glycol; 1 ,3-propanediol; 1 ,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; 1 ,2-propanediol; 1 ,3-butanediol; 2,3-butanediol; 1,3-pentanediol; 1,2-hexanediol; 3-methylpentane- 1 ,5-diol; 1,9-nonanediol; 2-methyloctane-l ,8-diol; 1,4-cyclohexanedimethanol; hydroquinone bis(hydroxyethyl)ether; diethylene glycol; dipropylene glycol; tripropylene glycol; ethanolamine; N-methyi-diethanolamine; N-ethyldiethanolamine, or a combination thereof.

In one embodiment, the diol component can be an ester diol formed by esterifying an aliphatic dicarboxylic acid with an aliphatic diol listed above. Examples of aliphatic dicarboxylic acids include, but are not limited to, adipic acid, azelaic, acid, or glutaric acid. In one embodiment, from about 0.01 to about 0.8 mole of dicarboxylic acid per mole of diol are reacted to produce the ester diol.

In one embodiment, the diol component is the reaction product between an aliphatic diol or triol and a lactone. In one embodiment, 0.01 to 2 moles of lactone per mole of diol or triol are reacted with one another to produce the diol component.

Examples of aliphatic diols in this embodiment include, but are not limited to, 1,4-cyclohexanedimethanol, neopentyl glycol, hexane-1,6-diol, ethylene glycol, butane-1,4-diol, or trimethylolpropane. Examples of aliphatic triols include, but are not limited to, glycerol or trimethylolpropane. In one embodiment, the lactone is epsilon- caprolactone.

In one embodiment, the cycloaliphatic diol is from 10 to 90% by weight of the diol component and the diol extender is from 10 to 90% by weight of the diol component, wherein the sum of the weight percentages of the cycloaliphatic diol and diol extender is equal to 100%.

In another embodiment, a polyol is used to prepare the thermoplastic polyurethane. Examples of polyols include, but are not limited to, a polyether polyol, a polyester polyol, a hydroxy-terminated polycarbonate, a hydroxy-terminated polybutadiene, a hydroxy-terminated polybutadiene-acrylonitrile copolymer, a hydroxy-terminated copolymer of a dialkyl siloxane and alkylene oxide, or a combination thereof. In one embodiment, the molecular weight of the polyol is from about 1,250 to about 10,000, preferably, from about 2,000 to about 8,000.

Examples of polyether polyols include, but are not limited to, polyoxyethylene glycol or polyoxypropylene glycol. In one embodiment, polyoxyethylene glycol or polyoxypropylene glycol can be capped with 1) ethylene oxide residues; 2) random and block copolymers of ethylene oxide and propylene oxide; 3) propoxylated tri- and tetrahydric alcohols such as glycerine, trimethylolpropane, or pentaerythritol; 4) polytetramethylene glycol, or 5) random and block copolymers of tetrahydrofuran and ethylene oxide and/or propylene oxide. In one embodiment, the polyether polyol is a random and block copolymer of ethylene and propylene oxide or polytetramethylene glycol. Other examples of polyether polyols useful in the present invention include, but are not limited to vinyl reinforced polyether polyols, such as the polymerization product between styrene and/or acrylonitrile and the polyether polyol.

In one embodiment, a polyether ester can be prepared by reacting a polyether polyol described above with a di- or trifunctional aliphatic or aromatic carboxylic acid.

Examples of useful carboxylic acids include, but are not limited to, adipic acid, azelaic acid, glutaric acid, isophthalic acid, terephthalic acid, or trimellitic acid. In one embodiment, the polyester polyol is the polymerization product between epsilon-caprolactone and ethylene glycol or ethanolamine. In one embodiment, the polyester polyol is prepared by the esterification of a polycarboxylic acid such as phthalic acid, terephthalic acid, succinic acid, glutaric acid, adipic acid, or azelaic acid and with a polyhydric alcohol such as ethylene glycol, butanediol, glycerol, trimethylolpropane, 1,2,6-hesanetriol, or cyclolocxancdimetloaiool and thc like. In onc

embodiment, the polyester polyol is prepared by esterifying a dimeric or trimeric fatty acid, optionally mixed with a monomeric fatty acid such as oleic acid, with a long chain aliphatic diol such as hexane-1,6-diol.

In one embodiment, a polyether diamine useful in the present invention is JEFFAMINE, which is manufactured by Jefferson Chemical Company.

In one embodiment, polycarbonates used to make the thermoplastic polyurethanes of the present invention containing hydroxyl groups useful in the present invention are prepared by reacting a diol, such as propane-1,3-diol, butane-1,4-diol, hexan-1,6-diol, diethylene glycol, triethylene glycol, or dipropylene glycol, with a diarylcarbonate (e.g. diphenylcarbonate) or with phosgene.

In one embodiment, siliconcontaining polyethers useful in the present invention are copolymers of alkylene oxides with dialkylsiloxanes such as dimethylsiloxane. The siliconcontaining polyethers disclosed in U.S. Pat. No.

4,057,595, which is hereby incorporated by reference in its entirety, can be used in the present invention.

In one embodiment, hydroxy-terminated poly-butadiene copolymers sold under the tradename POLY BDs Liquid Resins manufactured by Arco Chemical Company are useful in the present invention. In one embodiment, hydroxy- and amine-terminated butadiene/acrylonitrile copolymers sold under the tradename HYCARs hydroxyl-terminated (HT) Liquid Polymers and amine-terminated (AT) Liquid Polymers, respectively, can be used in the present invention.

In one embodiment, the thermoplastic polyurethane is ISOPLAST, which is manufactured by the Dow Chemical Company. There are a number of different thermoplastic polyurethanes sold under the tradename TSOPLASTQ; however, these thermoplastic polyurethanes are typically the reaction product between

methylenebis(phenyl isocyanate) and a number of different-glycols. In one embodiment, the thermoplastic polyurethane is ISOPLAST 301, which is the reaction product between methylenebis(phenyl isocyanate), 1,6-hexanediol, cyclohexanedimethanol, and polytetramethylene glycol.

In one embodiment, the thermoplastic polyurethane is from 1 to 10%, preferably from 1 to 9%, more preferably from 1 to 8%, more preferably from 1 to 7%, more preferably from 1 to 6%, more preferably from 1 to 5%, more preferably from I to 4%, more preferably from 1 to 3%, more preferably from 1 to 2%, or even more preferably from 1 to 1.5% by weight of the mixture, wherein the sum of the weight percentages ofthe thermoplastic polyurethane and the polymer is equal to 100 %.

One advantage of the present invention is that only a small amount of thermoplastic polyurethane is required to produce a composite with superior physical properties. Moreover, by using higher amounts of thermoplastic polyurethane, which is disclosed in the prior art, the viscosity of the resultant composite prior to solid state polymerization also increases. The higher the viscosity, the more difficult it is to extrude the composite. The present invention avoids these processing problems by using only a small amount of thermoplastic polyurethane.

In one embodiment, the polymer is poly(butylene terephthalate) and the thermoplastic polyurethane is ISOPLASTs 301. In one embodiment, the polymer is poly(ethylene terephthalate) and the thermoplastic polyurethane is ISOPLASTs 301.

Other additives known in the art can be added to the polymer composite.

Examples of additives include, but are not limited to, a colorant, a filler, a processing aid, a plasticizer, a nucleating compound, a stabilizer, an antioxidant, a mold release agent, a flame retardant, a reinforcing agent, or a combination thereof. In one embodiment, the reinforcing agent comprises calcium carbonate, talc, iron oxide, mica, montmorillonite, clay, or a combination thereof.

In one embodiment, the additive can be added to the composition prior to solid state polymerization. In another embodiment, the additive can be added to the composition after the composition has been solid state polymerized.

Prior to solid state polymerization, the composition comprising the polymer and thermoplastic polyurethane can be admixed using techniques known in the art. In one embodiment, the composition can be prepared during the synthesis of the polymer (e.g. addition of the thermoplastic polyurethane to a mixture of monomers used to produce the polymer), melt processing the thermoplastic polyurethane into the polymer after the polymer is produced, or by admixing the polymer and the thermoplastic polyurethane in a solvent.

In one embodiment, prior to solid state polymerization, the composition can be produced by a Brabender Plastograph, Haake plastograph melt mixer (Rheocord 90), a single screw extruder, or a twin screw extruder (such as Werner Pfleiderer equipment).

The temperature and time required to melt mix the polymer and thermoplastic polyurethane depends upon the polymer and thermoplastic polyurethane selected; however, one of ordinary skill in the art can deduce these parameters.

Once the composition comprising the polymer and thermoplastic polyurethane has been prepared, the composition is extruded into chips or pellets. The pellets or chips are now ready to undergo solid state polymerization. As described above, solid state polymerization is conducted at an elevated temperature, wherein the temperature is below the melting point of the polymer. Typically, solid state polymerization is conducted under a stream of an inert gas in order to remove volatile reaction products.

In one embodiment, solid state polymerization is conducted at a temperature just below the melting point of the polymer having at least one isocyanate reactive group.

A variety of instrumentation and techniques known in the art can be used to conduct the solid state polymerization step. In one embodimcnt. plug flow reactors can

be used to solid state polymerize the polymer and thermoplastic polyurethane. In this embodiment, the pellets or chips are introduced into the top of a tall, cylindrical vessel and removed from the bottom at the same rate. The temperature at which the pellets or chips are heated can vary depending upon the polymer selected. In one embodiment, the pellets or chips are heated at from 180 to 250 C. The residence time in the vessel can also vary. In one embodiment, the residence time is from 4 to 18 hours. This process of solid state polymerization is disclosed in U.S. Patent No. 4,064,112, which is incorporated by reference in its entirety.

The invention further relates to the polymer compositions produced by the present invention.

Not wishing to be bound by theory, it is believed that during solid state polymerization, the thermoplastic polyurethane depolymerizes to produce an isocyanate intermediate in situ. The polymer, which has at least one isocyanate reactive group, reacts with the isocyanate intermediate. This ultimately results in the chain extension of the polymer, which increases the molecular weight of the polymer. The thermoplastic polyurethane increases the solid state rate, which translates to the production of high molecular weight compositions using shorter heating and residence times. Additionally, the process of the present invention does not use toxic and hazardous isocyanates, which are disclosed in the art as chain extenders, to increase the molecular weight of the polymer.

Any of the polymer compositions produced by the present invention can be molded or shaped to produce a desired article by using extrusion, pultrusion, injection. molding, compression molding, blow molding. extrusion blow molding, or spinning techniques.

EXAMPLES The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the methods and compositions of matter claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in C or is at room temperature and pressure is at or near atmospheric.

Examples 1-4 All of the formulations in Table 1 were prepared using poly(butylene terephthalate) (PBT) having an initial molecular weight of 15,000 as determined by gel permeation chromatography against poly(ethylene terephthalate) standards. All samples contained IRGANOX 1010, which is a phenolic antioxidant commonly known in the art. The thermoplastic polyurethane used in Examples 1-4 was ISOPLAST4> 301, which is manufactured by Dow Chemical Company. Melt processing was done by mixing on a twin extruder with a set point of 240°C. Examples 1-4 were extruded into a water bath and pelletized. Solid stating was performed at 190"C. Molecular weights were determined by gel permeation chromatography (GPC).

Examples IA-B and 3A-B contain no thermoplastic polyurethane, while Examples 2A-B and 4A-B contain 3% of ISOPLASTS 301. Table 1 shows that after both 6 and 8 hours of solid state time, the molecular weights of Examples 2A-B and 4A-B are significantly higher than those of Examples I A-B and 3A-B. Additionally, Examples 2A-B and 4A-B obtain higher molecular weights after only 6 hours of solid stating when compared to Examples IB and 3B, which were solid state polymerized for S hours in the absence of the thermoplastic polyurethane. The data in Table 1 demonstrates that a thermoplastic polyurethane can increase the solid stating rate as well as increase the molecular weight of the polymer.

Table 1. Effect of Solid Stating on the Molecular Weight of PBT Sample # 1A 1B 2A 2B 3A 3B 4A 4B PBT, % 99.75 99.75 96.75 96.75 99.75 99.75 96.75 96.75 ISOPLAST# 301, % 0 0 3 3 0 0 3 3 IRGANOX 1010, % 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Solid Stating Time, hrs 6 8 6 8 6 8 6 8 Mn 16,564 18,752 20,389 22,960 16,520 18,371 19,623 21,045 Mw 46,715 54,230 61,681 71,435 47,299 52,217 58,338 63,884 Mz 78,448 93,058 108,452 126,693 79,718 88,085 100,686 112,146

Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.