Thermoplastic polyurethane composition comprising imidazole groups, articles and methods

Abstract

Articles and thermoplastic polyurethane compositions are described that comprise a thermoplastic polyurethane. Illustrative articles include a film, a structured film, a polishing layer, a molded component, or fibers. The thermoplastic polyurethane comprises the reaction product of a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; and d) at least one hydroxy -functional imidazole compound. The hydroxy -functional imidazole compound functions as a catalyst. The reaction product may further comprise e) a mono-alcohol, and / or f) a reactive compound that comprises hindered amine groups, that end cap the polyurethane chains. Also described are hydroxy¬ functional imidazole compounds and methods of making a thermoplastic polyurethane article.

Description

[0001] THERMOPLASTIC POLYURETHANE COMPOSITION COMPRISING IMIDAZOLE GROUPS, ARTICLES AND METHODS Summary In one embodiment, articles are described that comprise a thermoplastic polyurethane. Illustrative articles include a film, a structured film, a polishing layer, a molded component, or fibers. The thermoplastic polyurethane comprises the reaction product of a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; and d) at least one hydroxy-functional imidazole compound. The hydroxy-functional imidazole compound functions as a catalyst. In some embodiments, the reaction product further comprises at least one of the following: e) a mono-alcohol, f) a reactive compound that comprises hindered amine groups, or a combination of e) and f). The hydroxy-functional imidazole compound and mono-alcohol end cap the polyurethane chains. In another embodiment, an article is described comprising a thermoplastic polyurethane that is the reaction product of a mixture comprising: a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; and d) one or more hydroxy-functional imidazole compounds. The thermoplastic polyurethane of the article is substantially free of dienophile moieties or the reaction product of a diene and dienophile thereof. In another embodiment, hydroxy-functional imidazole compounds are described consisting of 1-dodecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol, 1-tetradecoxy-3-(2-ethyl-5-methyl-imidazol- 1-yl)propan-2-ol, and combinations thereof. Also described are methods of making a thermoplastic polyurethane article. Brief Description of the Figures FIG.1 is a graph of micro-compounder axial force and time; FIG. 2 is a schematic cross-sectional diagram of a polishing pad in accordance with some embodiments of the present disclosure. Detailed Description Presently described are polyurethanes, e.g. thermoplastic polyurethanes. The polyurethanes are prepared from at least one isocyanate including a diisocyanate and at least one polyol including a diol. In some embodiments, other components are utilized in the synthesis of the polyurethane such as a diol chain extender, a mono-alcohol, a reactive compound comprising a hindered amine, and combinations thereof. The polyurethane reaction is catalyzed by the presence of a hydroxy-functional imidazole compound. The use of the hydroxy-functional imidazole compound eliminates the need for common metal-containing catalysts. Such hydroxy-functional imidazole compounds also react with an isocyanate group, thereby terminating or in other words end-capping at least a portion of the polyurethane chains. Thus, the polyurethane comprises little or no residual catalyst. Hydroxyl-functional Imidazole Compound The hydroxy-functional imidazole compound comprises an imidazole moiety and a (e.g. single) hydroxy group. Imidazole is a five-membered heterocyclic moiety with three carbon atoms, two nitrogen atoms, and two double bonds. The hydroxy-functional imidazole compound may be represented by the following Formula IA: wherein R1, R2, R3, R4 are independently hydrogen or an alkyl group having 1-4 carbon atoms (e.g. methyl or ethyl); R5 is hydrogen or an alkyl group having 1-4 carbon atoms (e.g. methyl or ethyl) or an ether group with up to 20 carbon atoms; or R4 together with R5 is a C4-C6 cycloaliphatic group. Some representative compounds include for example1-dodecoxy-3-(2-ethyl-5-methyl-imidazol- 1-yl)propan-2-ol; 1-tetradecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol; 1-butoxy-3-(2- methylimidazol-1-yl)propan-2-ol; 2-(2-ethyl-4-methyl-imidazol-1-yl)cyclohexanol; and 2-(2-ethyl-4-methyl-imidazol-1-yl)ethanol. Other hydroxyl-functional imidazole isomers include for example 1-(2'-hydroxypropyl)-imidazole, 1-(2'-hydroxypropyl)-2-methylimidazole, 1-(2'-hydroxyethyl)- imidazole, 1-(2'-hydroxyethyl)-2-methylimidazole, 1-(3'-hydroxypropyl)-imidazole, and 1-(3'-hydroxypropyl)-2-methylimidazole. With reference to the forthcoming examples, the hydroxy-functional imidazole compounds are generally prepared by reacting alkyl imidazole (e.g.2-ethyl-4-methylimidazole or 2-methylimidazole) with an epoxy compound. Representative epoxy compounds include for example C2-C14 alkyl monoglycidyl ethers. In some embodiments, the alkyl may be a single alkyl such as butyl or a cycloalkyl group such as cyclohexane. In other embodiments, the epoxy compound may comprise a combination of alkyl groups with different chain lengths, such as C12 and C14. Suitable amounts of the hydroxy-functional imidazole catalyst can range from 0.05% to 2% wt.%. In some embodiments, the amount of hydroxy-functional imidazole catalyst in the reaction mixture is at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1 wt.%. In some embodiments, the amount of hydroxy-functional imidazole catalyst in the reaction mixture is no greater than 1.5, 1, 0.75, or 0.50 wt.%. A single hydroxy-functional imidazole compound may be utilized or a combination of such compounds. The polyurethane comprises nominally the same amount of imidazole (e.g. terminal) groups. The hydroxy-functional imidazole catalyst may be used in combination with other conventional polyurethane catalysts. Useful catalysts in the polymerization of polyurethanes include aluminum-, bismuth-, tin-, vanadium-, zinc-, mercury-, and zirconium-based catalysts, amine catalysts, and mixtures thereof. Common tin catalysts include, but are not limited to, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin di acetyl acetonate, dibutyltin dimercaptide, dibutyltin dioctoate, dibutyltin dimaleate, dibutyltin acetonylacetonate, and dibutyltin oxide. However, when the hydroxy-functional imidazole compound(s) are the sole catalyst, the polyurethane can advantageously be free of residual metal catalyst and thus entirely free of metal. In some embodiments, the thermoplastic polyurethane may be represented by the following Formula II: functional imidazole compound; R6 is derived from a diisocyanate; R7 is derived from a diol; n is the number of polymerized units of the diisocyanate diol and (e.g. polymeric) diol; R8 is derived from a diol chain extender; m is the number of polymerized units of diisocyanate diol and diol chain extender; m is zero in the absence of diol chain extender; and X is an imidazole group that can be represented by Formula IB: . comprises a mono-alcohol, X is independently the imidazole group or an alkyl group derived from the mono-alcohol. The moles of hydroxyl-functional imidazole compound divided by the mole of mono-alcohol is the molar ratio of hydroxyl-functional imidazole compound to mono-alcohol. A molar ratio of 1.0 indicates that about half of the polyurethane chains comprise an imidazole end cap moiety and about half of the polyurethane chains comprise an alkyl group (derived by the mono-alcohol). The molar ratio of hydroxyl-functional imidazole compound to mono-alcohol can range from 0.1 to 10. In some embodiments, the molar ratio of hydroxyl-functional imidazole compound to mono-alcohol is at least 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1. In some embodiment, the molar ratio of hydroxyl-functional imidazole compound to mono-alcohol is no greater than 9, 8, 7, 6, 5, 4, 3, or 2. It is appreciated that when the reactive mixture comprises a mono-alcohol, a statistical (e.g. small) portion of the polyurethane chains can be end capped with the mono-alcohol at both ends. Although the conjugated diene group of imidazole (e.g. terminal groups) are known to be reactive with compounds, the thermoplastic polyurethane presently described is typically formed into an article, such as by thermal extrusion, in the absence of dienophile moieties. Thus, the thermoplastic polyurethane of the article comprises the same concentration of imidazole terminal groups as the thermoplastic polyurethane the article was prepared from. In other words, at least 90% or greater of the total amount of hydroxy-functional imidazole compound of the reaction mixture is present in the thermoplastic polyurethane and the articles thereof as imidazole (e.g. terminal) groups. It is appreciated that if the thermoplastic polyurethane contained a very small number of dienophile moieties that react with the imidazole groups, the presence thereof may have little or no effect on the properties of the article. Thus, in other embodiments, the thermoplastic polyurethane of the articles comprises less than 0.01, 0.005, 0.0001 mmol / g of dienophile moieties. In some embodiments, the amount of dienophile moieties is sufficiently small such that viscosity of the thermally extruded thermoplastic polyurethane of the article does not increase the viscosity by more than 10% as compared to the same composition having zero dienophile moieties. Polyol The polyurethane described herein is prepared from one or more polyols. Although (e.g. small concentrations of) polyol having greater than two hydroxyl group can be utilized, the polyol is typically predominantly a diol. In some embodiments, the polyol has a number average molecular weight of at least 400, 450, or 500 Daltons (Da). In some embodiments, the polyol has a number average molecular weight of no greater than 10,000 Da, 5,000 Da, or 2,000 Da. In some embodiments, the polyol may be at least one of a polyester polyol, a polyether polyol, a polycarbonate polyol and a hydroxyl terminated polybutadiene. Combinations of different types of polyols may be used. In some embodiments, the polyurethane described herein is prepared from polyester polyol. The polyester polyol may be a product of a condensation reaction such as a polycondensation reaction. In embodiments where polyester polyol is made according to a condensation reaction, the reaction can be between one or more carboxylic acids and one or more diols. An example of a suitable carboxylic acid includes a carboxylic acid according to Formula III, having the structure: In Formula III, R3 may be chosen from substituted or unsubstituted C1-C40 alkylene, C2-C40 alkylene, C2-C40 alkenylene, C4-C20 arylene, C4-C20 cycloalkylene and C4-C20 aralkylene. Specific examples of suitable carboxylic acids include, but are not limited to, glycolic acid (2-hydroxyethanoic acid), lactic acid (2-hydroxypropanoic acid), succinic acid (butanedioic acid), 3-hydoxybutanoic acid, 3- hydroxypentanoic acid, terephthalic acid (benzene-1,4-dicarboxylic acid), naphthalene dicarboxylic acid, 4-hydroxybenzoic acid, 6-hydroxynaphtalane-2-carboxylic acid, oxalic acid, malonic acid (propanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), ethonic acid, suberic acid (octanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), glutaric acid (pentanedioic acid), dedecandioic acid, brassylic acid, thapsic acid, maleic acid ((2Z)-but-2-enedioic acid), fumaric acid ((2E)-but-2-enedioic acid), glutaconic acid (pent-2-enedioic acid), 2-decenedioic acid, traumatic acid ((2E)-dodec-2-enedioic acid), muconic acid ((2E,4E)-hexa-2,4-dienedioic acid), glutinic acid, citraconic acid((2Z)-2-methylbut-2-enedioic acid), mesaconic acid ((2E)-2-methyl-2-butenedioic acid), itaconic acid (2-methylidenebutanedioic acid), malic acid (2-hydroxybutanedioic acid), aspartic acid (2-aminobutanedioic acid), glutamic acid (2-aminopentanedioic acid), tartonic acid, tartaric acid (2,3-dihydroxybutanedioic acid), diaminopimelic acid ((2R,6S)-2,6-diaminoheptanedioic acid), saccharic acid ((2S,3S,4S,5R)-2,3,4,5-tetrahydroxyhexanedioic acid), mexooxalic acid, oxaloacetic acid (oxobutanedioic acid), acetonedicarboxylic acid (3-oxopentanedioic acid), arbinaric acid, phthalic acid (benzene-1,2-dicarboxylic acid), isophthalic acid, diphenic acid, 2,6-naphtalenedicarboxylic acid, or a mixture thereof. An example of a suitable diol for the condensation reaction includes a diol according to Formula IV, having the structure: In Formula IV, R4 may be chosen from substituted or unsubstituted C1-C40 alkylene, C2-C40 alkenylene, C4-C20 arylene, C1-C40 acylene, C4-C20 cycloalkylene, C4-C20 aralkylene, and C1- C40 alkoxyene, and R5 and R5’ are independently chosen from -H, substituted or unsubstituted C1-C40 alkyl, C2-C40 alkenyl, C4-C20 aryl, C1-C20 acyl, C4-C20 cycloalkyl, C4-C20 aralkyl, and C1- C40 alkoxy. Suitable polyols include, but are not limited to ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3- butanediol, 1,4-butanediol, 1,5-pentane- diol, 1,6-hexanediol, 2, 2- dimethyl- 1,3 -propanediol, 1,4- cyclohexanedimethanol, deca- methylene glycol, dodecamethylene glycol, glycerol, trimethylolpropane, and mixtures thereof. In some embodiments, the polyol is made via a ring opening polymerization, e.g. the ring opening polymerization of ε-caprolactone. Suitable polyester polyols include, but are not limited to, polybutylene adipate, polyethylene adipate, poly(diethylene glycol adipate), polyhexamethylene adipate, poly(neopentyl glycol) adipate, poly(butylene adipate-co-phthalate), polycaprolactone or copolymers thereof. Combinations of different polyester polyols may be used. In some embodiments, the polyurethane is prepared from a polyether polyol, including but not limited to, polyoxyalkylene polyols, polyoxycycloalkylene polyols, and alkylene oxide adducts thereof. In some embodiments, the polyether-polyols may be at least one of polyoxyethylene polyol (e.g. polyethylene glycol), polyoxypropylene polyol (e.g. polypropylene glycol), polyoxytetramethylene polyol (e.g. polyoxytetramethylene glycol), copolymers thereof and mixtures thereof and may have a hydroxyl functionality of from 2 to 6, in particular from 2 to 4, and in particular about 2. Polyether polyols are well known and may be prepared by reactions of compounds containing hydroxyl groups with, for example, ethylene oxide, propylene oxide, tetramethylene oxide in the presence of a base catalyst, yielding polyoxyethylene polyol, polyoxypropylene polyol and polyoxytetramethylene polyol, respectively. Copolymers containing at least two of ethylene oxide, propylene oxide and tetramethylene oxide may also be used. A variety of hydroxyl group containing compounds can be used to initiate the reaction including, for example, ethylene glycol, propylene glycol, butylene glycol, glycerine, 2,2-dimethylolpropane, pentaerythritol and the like. Examples of commercially available polyether polyols include Arcol polyether polyols available under the trade designation PPG 425, PPG 725, LHT 112 and LHT 240, (from Arco Chemical Co., Newtown Square, PA); polyethylene glycols such as those available under the trade designation Carbowax Sentry provided (Dow Chemical Co., Midland, MI); PLURACOL E 1450 polyethylene glycol (BASF Corp., Parsippany, NJ); and PolyTHF poly(tetramethylene oxide) polyol (BASF Corp., Parsippany, NJ). In some embodiments, the polyol of the reactive mixture may be a polycarbonate polyol. The polycarbonate polyol can be obtained from the reaction of aliphatic diols, such as 1,4-butanediol and 1,6- hexanediol, with phosgene, diaryl-carbonates such as diphenylcarbonate or with cyclic carbonates such as ethylene or propylene carbonate. The aliphatic diol may be any one of or combinations of the diols discussed with respect to Formula IV. Examples of commercially available polycarbonate polyols include ARAMACO PERFORMANCE MATERIALS CONVERGE POLYO 212-10, 212-20, CPX- 2001-112, CPX-2502-56a and HMA-2 available from Aramaco Performance Materials, LLC, Houston, TX. In some embodiments, the polyol of the reactive mixture may be a hydroxyl terminated butadiene. The hydroxyl terminated butadiene may be a hydroxyl terminated polybutadiene and the polybutadiene may be a homopolymer or copolymer. Examples of commercially available hydroxyl terminated butadienes include “LIQUIFLEX H” from Petroflex, Wilmington, DE, and POLY-BD- 45HTLO from Cray Valley USA, LLC, Exton, PA. A polyol is typically present in the reaction mixture at an amount of at least 15, 20, 25, 30, 35, 40, 45, or 50 wt. % based on the weight of the reactive mixture. In some embodiments the amount of polyol present in the reactive mixture is no greater than 80, 75, 70,65, 60, 55, 50, 45, 40, 35, 30, 25, or 20 wt.% based on the weight of the reactive mixture. The amount of polyol in the reaction mixture may be described as a range based on the minimum and maximum amounts just described. The polyurethane comprises nominally the same amount of polymerized polymeric polyol. In some embodiments, the polyol is a polymeric polyol, such as a polyester polyol. Diol Chain Extender The reactive mixture optionally comprises a diol chain extender. The diol chain extender may be described by Formula IV, where R4 is chosen from substituted or unsubstituted C1-C16 alkylene, C2- C16 alkenylene, C4-C20 arylene, C1-C16 acylene, C4-C16 cycloalkylene, C4-C16 aralkylene, and C1- C16 alkoxyene, and R5 and R5’ are independently chosen from -H, substituted or unsubstituted C1-C16 alkyl, C2-C16 alkenyl, C4-C16 aryl, C1-C16 acyl, C4-C16 cycloalkyl, C4-C16 aralkyl, and C1-C16 alkoxy and R5 and R5’ are typically not hydroxy. Suitable diols include, but are not limited to, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2, 2- dimethyl- 1,3 -propanediol, 1,4-cyclohexanedimethanol, decamethylene glycol, diethylene glycol, hydroquinone bis(2-hydroxyethyl) ether, and dodecamethylene glycol. In some embodiments, the diol chain extender includes at least one of a C1-C16 aliphatic diol and C4-C16 cycloaliphatic diol. In some embodiments, the C1-C16 aliphatic diol includes a C1-C16 alkylene and, optionally, the C1-C16 alkylene is a linear, C2-C16 alkylene with hydroxyl substitution at the two terminal carbon atoms. In some embodiments, the diol chain extender has molecular weight of less than 400 Daltons, less than 350 Daltons or less than 300 Daltons. For example, the molecular weight of the diol chain extender is at least 30 or 50 Daltons. In some embodiments, the molecular weight of the diol chain extender may be the number average molecular weight. A diol chain extender is optionally present in the reaction mixture at an amount of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt. % based on the weight of the reactive mixture. In some embodiments the amount of diol chain extender is present in the reactive mixture is no greater than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 wt.% based on the weight of the reactive mixture. The amount of diol chain extender in the reaction mixture may be described as a range based on the minimum and maximum amounts just described. The polyurethane comprises nominally the same amount of polymerized diol chain extender. Mono-alcohol In some embodiments, the reactive mixture includes a mono-alcohol. In some embodiments, the mono-alcohol may be a fatty alcohol. Fatty alcohols are typically straight chain primary alcohols with a hydroxyl end group. Fatty alcohols include 1-decanol, dodecanol, stearyl, oleyl, and lauryl alcohols. The fatty alcohol typically has a C6-C32 (e.g. alkyl) chain length. In some embodiments, the fatty alcohol has an (e.g. alkyl) chain length of no greater than 30, 28, 26, 24, 22, 20, 18, 16, or 12. In some embodiments, the reactive mixture includes a mono-alcohol with a relatively high boiling point to prevent evaporation of the mono-alcohol before the urethane polymerization is complete. The mono-alcohol may have a boiling point greater than the reaction temperature during the urethane polymerization. In some embodiments, the mono-alcohol includes a branched aliphatic group. In some embodiments, the mono- alcohol has a chain length between C8-C24, and in some embodiments, the mono-alcohol has a chain length between C10-C20. Branched mono-alcohols include 2-ethyl-1-hexanol, 2-butyl-1-octanol, 2- pentyl-1-nonanol, 2-hexyl-1-decanol, 2-octyl-1-dodecanol, 2-decyl-1-tetradecanol, isooctanol, isodecanol, isododecanol, 2,4,4-trimethyl-1-pentanol, and 3,5,5-trimethyl-1-hexanol. In some embodiments, the mono-alcohol may be a secondary alcohol. Secondary mono-alcohols include 2- octanol, 3-octanol, 4-octanol, 2-nonanol, 4-nonanol, 5-nonanol, 2-decanol, and 2-dodecanol. In some embodiments, the mono-alcohol may contain ether groups. Ether-containing mono-alcohols include diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, di(propylene glycol) butyl ether, di(propylene glycol) propyl ether, di(propylene glycol) methyl ether, propylene glycol butyl ether, and propylene glycol propyl ether. In some embodiments, a small amount of mono-alcohol is employed to end-cap at least a portion of the polyurethane chains. In some embodiments, the amount of mono-alcohol in the reaction mixture is at least 0.05, 0.1, 0.2, 0.3, 0, 4 or 0.5 wt.%. In some embodiments, the amount of mono-alcohol in the reaction mixture is no greater than 1, 0.75, 0.50, 0.4, 0.3, 0.2, or 0.1 wt.%. The amount of mono-alcohol in the reaction mixture may be described as a range based on the minimum and maximum amounts just described. A single mono-alcohol may be utilized or a combination of mono-alcohols. The polyurethane comprises nominally the same amount of terminal groups derived from mono-alcohols. In some embodiments, the reaction mixture may optionally contain a polyol having at least three hydroxyl groups and / or a polyisocyanate having at least three corresponding isocyanate groups. In this case, the polyol and or polyisocyante may act as a branching agent. The amount of polyol and / or polyisocynate must be limited, in order to maintain the general thermoplastic characteristics of the resulting polyurethane. However, components of this nature may be used to increase the molecular weight or modify the viscosity characteristic of the polyurethane. Diisocyanate The polyurethane is prepared from a diisocyanate. The diisocyanate is not particularly limited and can be monomeric, oligomeric or polymeric. An example of a suitable diisocyanate includes a diisocyanate according to Formula V having the structure: Formula V. In Formula V, R6 is chosen from substituted or unsubstituted C1-C40alkylene, C2-C40alkenylene, C4-C20 arylene, C4-C20 arylene-C1-C40 alkylene-C4-C20 arylene, C4-C20 cycloalkylene, and C4-C20 aralkylene. In some embodiments, the diisocyanate is chosen from dicyclohexylmethane-4,4’- diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3- phenylene diisocyanate, m-xylylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, poly(hexamethylene diisocyanate), 1,4-cyclohexylene diisocyanate, 4-chloro-6-methyl-1,3-phenylene diisocyanate, 4,4’-diphenylmethane diisocyanate, 2,4’-diphenylmethane diisocyanate, 1,4- diisocyanatobutane, 1,8-diisocyanatooctane, 2,5-toluene diisocyanate, methylene bis(o-chlorophenyl diisocyanate, (4,4’-diisocyanato-3,3’,5,5’-tetraethyl) diphenylmethane, 4,4’-diisocyanato-3,3’- dimethoxybiphenyl (o-dianisidine diisocyanate), 5-chloro-2,4-toluene diisocyanate, 1-chloromethyl-2,4- diisocyanato benzene, tetramethyl-m-xylylene diisocyanate, 1,12-diisocyanatododecane, 2-methyl-1,5- diisocyanatopentane, 2,2,4-trimethylhexyl diisocyanate, or a mixture thereof. In some embodiments, the diisocyanate may be a chain extended diisocyanate, i.e. the reaction product of a diisocyanate and a dihydroxyl terminated oligomer or polymer, e.g. a dihydroxyl terminated, linear oligomer or polymer. During the reaction, excess diisocyanate is used to ensure that at least 80% by wt., 90% by wt., 95% by wt., 97% by wt.98% by wt., 99 wt. % by wt. or 99.5 wt. % of the product of the reaction is also a diisocyanate. The dihydroxyl terminated oligomer or polymer is not particularly limited and may include, for example, dihydroxyl terminated, linear polyesters and dihydroxyl terminated, linear polyethers. Polyester polyols, particularly polyester diols previously discussed with respect to the polyester polyols of the present disclosure may be used to form the chain extended diisocyanate. In some embodiments, the polyester polyol of the chain extended diisocyanate may include the reaction product of one or more C2-C12 diol and one or more C2-C12 diacid. In some embodiments, the diisocyanate includes a diphenylmethane diisocyanate, a reaction product of diphenylmethane diisocyanate and a hydroxyl terminated, linear oligomer or polymer, toluene diisocyanate, a reaction product of toluene diisocyanate and a hydroxyl terminated, linear oligomer or polymer and combinations thereof. One exemplary chain extended diisocyanate is an ethylene-co-butylene adipate polyester terminated with 4,4’-diphenylmethane diisocyanate (MDI) available under the trade designation “RUBINATE 1234”, available from Huntsman Corporation, The Woodlands, TX. In some embodiments, the amount of diisocyanate in the reaction mixture is at least 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65 wt. % of the reaction mixture. In some embodiments, the amount of diisocyanate in the reaction mixture is no greater than 70, 65, 60, 55, 50, or 45 wt. % of the reaction mixture. The polyurethane comprises nominally the same amount of polymerized diisocyanate. In some embodiments, the diisocyanate comprises an aromatic diisocyanate such as MDI or a derivative thereof. Reactive Compound Comprising Hindered Amine Groups In some embodiments, reactive mixture further comprises a reactive compound comprising hindered amine groups. The reactive compound may be a multifunctional amine having one of the following structures:

[0002] In some embodiments, X is an integer from 0 to 10, inclusive of the endpoints, R1 is a linear or branched aliphatic group, cyclic aliphatic group, aromatic group or a compound containing an aromatic group having from 2 to 20 carbon atoms, R2 is a linear or branched alkyl group having from 1 to 20 carbon atoms and R2’ is hydrogen or a linear or branched alkyl group having from 1 to 20 carbon atoms. In some embodiments, X may be an integer from 0 to 5, from 0 to 3, from 1 to 10, from 1 to 5 or from 1 to 3, inclusive of the endpoints. In some embodiments, R1 is a linear or branched aliphatic group, cyclic aliphatic group, aromatic group or a compound containing an aromatic group having from 2 to 16 carbon atoms, from 2 to 12 carbon atoms or from 2 to 8 carbon atoms. In some embodiments, R2 is a linear or branched alkyl group having from 1 to 16 carbon atoms, from 1 to 12 carbon atoms, from 1 to 10 carbon atoms or from 1 to 8 carbon atoms and / or R2’ is a hydrogen or a linear or branched alkyl group having from 1 to 16 carbon atoms, from 1 to 12 carbon atoms, from 1 to 10 carbon atoms or from 1 to 8 carbon atoms. In some embodiments, R2 is a linear or branched alkyl group having from 1 to 10 carbon atoms and R2’ is a hydrogen. Mixtures of multifunctional amines Formula VI and Formula VII may be used. The multifunctional amines may be prepared by the reaction of N,N’-(bis-2,2,6,6- tetramethylpiperidin-4-yl)hexane-1.6-diamine and at least one of (i) a dihalogenated, alkyl modified 1,3,5-triazin-2-amine, (ii) a diacid and (iii) a diacyl halide. The dihalogenated, alkyl modified 1,3,5- triazin-2-amine may include at least one of chloro, bromo and fluoro substitution. Examples of suitable dihalogented, alkyl modified 1,3,5-triazin-2-amines include 4,6-dichloro-N-octyl-1,3,5-triazin-2-amine, 4,6-dichloro-N,N-dimethyl-1,3,5-triazin-2-amine, 4,6-dichloro-N,N-dipropyl-1,3,5-triazin-2-amine, 4,6- dichloro-N,N-dihexyl-1,3,5-triazin-2-amine, 4,6-dichloro-N-(1,1,3,3-tetramethylbutyl)-1,3,5-triazin-2- amine and the like. Combinations of dihalogented, alkyl modified 1,3,5-triazin-2-amines may be used. An exemplary multifunctional amine that may be prepared from the reaction of N,N’-(bis-2,2,6,6- tetramethylpiperidin-4-yl)hexane-1.6-diamine and a dihalogenated, alkyl modified 1,3,5-triazin-2-amine is Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazin-2,4-iyl][(2,2,6,6-tetramethyl-4- piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]), available under the trade designation CHIMASSORB 944 from, BASF, Florham Park, New Jersey. Examples of suitable diacids include terephthalic acid (e.g., 1,4 terephthalic acid), 1,4 naphthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, succinic acid, adipic acid, azelaic acid, maleic acid, glutaric acid, suberic acid, sebacic acid, dodecanedionic acid, 1,4-cyclohexanedicarboxylic acid, and the like. Combinations of diacids may be used. Examples of suitable diacyl halides include bromine, chlorine or fluorine substituted diacids, including bromine, chlorine or fluorine substituted diacids of the present disclosure, e.g.1,4-terephthaloyl dichloride, 1,4-terephthaloyl difluoride, isophthaloyl difluoride, 1,6-hexanedioyl dichloride, 1,4-proanedioyl dibromide and the like. Combinations of diacyl halides may be used. The multifunctional amines of Formulas VI and Formula VII each have two notable features. One feature is that each multifunctional amine contains two unhindered secondary amines (excluding the pendent amine with R2 substitution of the triazine), i.e. the two carbon atoms in a position alpha to the nitrogen of the unhindered secondary amine are not tertiary carbon atoms, or equivalently, the two carbon atoms in a position alpha to the nitrogen contain at least one bond to a hydrogen atom. The unhindered secondary amine functional groups are subsequently capable of reacting with other components of the reactive mixture. The second feature is that each multifunctional amine includes at least two hindered secondary amines, i.e. the two carbon atoms in a position alpha to the nitrogen of the hindered secondary amine are tertiary carbon atoms, or equivalently, the two carbon atoms in a position alpha to the nitrogen include no bonds to a hydrogen atom. Due to their steric hinderance, the hindered secondary amines are typical incapable of reacting with other components of the reactive mixture or the reaction rate is significantly reduced such that they do not play a significant role in forming the polyurethanes of the present disclosure. The number of hindered secondary amines in the multifunctional amines of Formula VI and Formula VII depends on the value of X. Thus, the number of hindered amines, N, in the multifunctional amines of Formula VI and Formula VII may vary according to the following: N = 2X +2. In some embodiments, the number of hindered secondary amines in the multifunctional amines of Formula VI and Formula VII may be from 2 to 22, from 2 to 16, from 2 to 12 or from 2 to 8. During the polymerization of the polyurethanes, the presence of the two unhindered secondary amines of the multifunctional amines of Formula’s VI and / or VII enable the compounds to react with the diisocyanate groups of the reaction mixture (covalent bond forming a urea linkage) and to be incorporated into the polyurethane backbone. This feature prevents migration and / or diffusion of the multifunctional amines and contributes to the hindered amine moieties being uniformly dispersed throughout the polyurethane. This feature also prevents extraction of the multifunctional amines from the polyurethanes during, for example, use as a polishing layer of a CMP pad. In some embodiments, the amount of reactive compound comprising a hindered amine (e.g. multifunctional amine) in the reactive mixture is at least 1, 2, 3, 4, or 5 wt.% based on the total weight of the reactive mixture. In some embodiments, the amount of multifunctional amine in the reactive mixture is no greater than 15 or 10 wt.%. The polyurethane comprises nominally the same amount of polymerized units of multifunctional amine. When the thermoplastic polyurethane is prepared from such multifunctional amine, the thermoplastic polyurethane further comprises one or both of the following polymerized units: The multifunctional amines contain hindered secondary amines and the hindered secondary amines enable the modification of the zeta potential of the polyurethanes. Typically, polyurethanes will have a zeta potential that is negative over the entire pH range from 2 to 10. Inclusion of the multifunctional amines with their hindered secondary amines into the polyurethane enables the formation of a polyurethane with a higher zeta potential or even a positive zeta potential at acidic pH. Additionally, the zeta potential of the polyurethanes of the present disclosure may be modified or “tuned” based on the amount of multifunctional amine added to the reactive mixture, i.e. covalently bonded into the polyurethane. Other additives may be included in the reactive mixture and polyurethanes of the present disclosure, including but not limited to antioxidants, light / UV light stabilizers, dyes, colorants, filler particles, abrasive particles, reinforcing particles or fibers, viscosity modifiers and the like. Additives that are not soluble in the reactive mixture, e.g. filler particles, abrasive particles, and reinforcing particles or fibers, are not included in the calculation of the weight percent of the components of the reactive mixture, i.e., they are not included in the total weight of the reactive mixture which is used as the basis for the wt. percentage of each component of the reactive mixture. Method of Making The polyurethanes are typically prepared by combining and reacting the following components at least one diol; at least one diisocyanate; and at least one hydroxy-functional imidazole catalyst. The reactive mixture may optionally further comprise chain extender(s); monoalcohol(s); and isocyanate- reactive compound(s) that comprises hindered amine groups. The components are combined and reacted within an extruder (e.g. microprocessor). The synthesis of the polyurethane is typically solvent-less. Thus, the reactive mixture lacks both organic solvent and water. The components are typically reacted at a temperature range of 150-220°C. The resulting thermoplastic polyurethane comprises imidazole terminal groups as a result of the hydroxy-functional imidazole catalyst being reacted with (e.g. end- capping) the isocyanate groups of the polyurethane. In some embodiments, the thermoplastic polyurethane further comprises unreactive terminal groups as a result of the mono-alcohol being reacted with (e,g. end-capping) the isocyanate groups of the polyurethane. As demonstrated by the forthcoming examples, in some embodiments, the extruder is a microcompounder that conveys information about the axial force, and the reaction attains half of the peak axial force in a shorter duration of time than the same reaction lacking the hydroxy-functional imidazole compound. In some embodiments, the ratio of the time to reach a half peak axial force compared to the time for the same reaction lacking the hydroxy-functional imidazole compound is less than 0.75, 0.50, or 0.25. As demonstrated by FIG.1, the axial force may reach a plateau in an amount of time less than the same reaction lacking the hydroxy-functional imidazole compound. When the reactive mixture comprises isocyanate-reactive compound(s) that comprises hindered amine groups, the axial force may not exhibit a plateau. However, the polyurethane is formed at a higher rate. The thermoplastic polyurethanes described herein may have stable viscosity at the processing conditions, e.g. temperature, pressure and time, used to fabricate articles therefrom. Amine catalysts, such as 1,4-diazabicyclo[2.2.2]octane, are often used to catalyze urethane polymerizations. However, at temperatures between 150°C and 220°C, these typical amine catalysts have been found to produce poor stability in the polymer viscosity in some polyurethane systems. It is presumed that these catalysts cause undesirable degradation reactions at high temperatures. The imidazole catalysts of the present invention have been found to produce polymer viscosities that are more stable at temperatures between 150 °C and 220 °C. In some embodiments, the complex viscosity of the polyurethane at temperatures in the range of 150°C and 220°C (e.g.150, 160, 170, 180, 190, 200, 210, 220°C) may be less than 15,000,000 cP, less than 10,000,000 cP, less than 5,000,000 cP, less than 3,000,000 cP or less than 1,000,000 cP. In some embodiments, the complex viscosity of the polyurethane is at least 35,000 cP, at least 40,000 cP, at least 50,000 cP, at least 75,000 cP, or at least 100,000 cP. In an oscillatory rheometry test, the resulting tan delta value can characterize the liquid-like behavior of the thermoplastic polyurethane. In some cases, tan delta values greater than 1.0 indicate that the materials is more liquid-like than solid-like, or in other words, that the material has melted. At at least one temperature between 150°C and 220°C, the tan delta value for the polyurethanes will be greater than 1.0, greater than 1.5, or greater than 2.0 and / or less than 30, less than 20, or less than 10. The thermoplastic polyurethanes described herein typically have a weight average molecular weight (Mw) of at least 10,000; 15,000; 25,000 or 50,000 g / mole. In some embodiments, the molecular weight is no greater than 500,000; 400,000; 300,000; 200,000 g / mole. Articles The thermoplastic polyurethane described herein can be used in a variety of applications and is particularly well suited for the formation of (e.g. thin) films, structured films such as a polishing layer, a molded component, or fibers. The method of making such articles generally comprises thermal extrusion of the thermoplastic polyurethane at elevated temperatures, e.g. temperatures ranging from 180°C to 250°C. One area where polyurethane films have recently been employed is as abrasive materials for various polishing applications, for example, Chemical Mechanical Planarization (CMP) polishing applications. The method comprises polishing a substrate (e.g. semiconductor wafer), using a polishing pad. The method generally comprises contacting the working surface of the polishing layer with the substrate surface; moving the polishing pad and the substrate relative to one another while maintaining contact between the working surface of the polishing pad and the substrate surface, wherein polishing is conducted in the presence of a polishing solution (e.g. slurry). The (e.g. a semiconductor wafer) substrate is moved relative to the polishing pad under a designated force or pressure, causing removal of material from the substrate surface. With reference to FIG.2, an illustrative polishing pad 50 which includes a polishing layer 10, having a working surface 12 and second surface 13 opposite working surface 12, and a subpad 30 adjacent to second surface 13. Optionally, a foam layer 40 is interposed between the second surface 13 of the polishing layer 10 and the subpad 30. The various layers of the polishing pad can be adhered together by any techniques known in the art, including using adhesives, e.g. pressure sensitive adhesives (PSAs), hot melt adhesives and cure in place adhesives. In some embodiments, the polishing pad includes an adhesive layer adjacent to the second surface. Use of a lamination process in conjunction with PSAs, e.g. PSA transfer tapes, is one particular process for adhering the various layers of polishing pad 50. Subpad 30 may be any of those known in the art. Subpad 30 may be a single layer of a relatively stiff material, e.g. polycarbonate, or a single layer of a relatively compressible material, e.g. an elastomeric foam. The subpad 30 may also have two or more layers and may include a substantially rigid layer (e.g. a stiff material or high modulus material like polycarbonate, polyester and the like) and a substantially compressible layer (e.g. an elastomer or an elastomeric foam material). Foam layer 40 may have a durometer from between about 20 Shore D to about 90 Shore D. Foam layer 40 may have a thickness from between about 125 micron and about 5 mm or even between about 125 micron and about a 1000 micron. Polishing layers may include a working surface (the surface of the polishing layer that contacts the substrate being polished) that includes a land region and plurality of asperities and / or pores, that facilitate the polishing process. In the case of asperities, it is generally desired to have the height of the tallest asperities to be uniform, creating a planar surface of asperity tips. This allows the substrate surface to make uniform contact across the set of asperities. Generally, it is desired to have the polishing layer be of a uniform thickness to allow the polishing layer working surface to be planar. The polishing layer is often in a film format having a thickness of less than 1000 microns and the corresponding polishing features may have dimensions, including height and / or depth, of between 20 to 100 microns. In some embodiments, the polishing layer further comprises a plurality of independent or interconnected macrochannels. One approach to creating the polishing features on the working surface of the polishing layer is through the use of a molding or embossing process. In this approach, a polishing layer may be prepared from a thermoplastic polyurethane as described herein that is melt processed, via an extruder for example, and cast onto an embossing roll that includes the negative image of the desired polishing layer features (if the features are on the scale of about 500 microns or less in size, e.g. height, this process may be called a microreplication process). The thermoplastic polyurethane is then cooled on the embossing roll to cause solidification followed by removal of the thermoplastic film with embossed features from the roll. With respect to melt processing, the thermoplastic may be synthesized, pelletized and then processed into film, at a later time. However, greater efficiency can be achieved by making the thermoplastic in-situ, in an extruder through reactive extrusion. The polyurethane produced can then be formed into a film. In one embodiment, the polishing layer may include at least 90% by weight, at least 95% by weight, at least 99% by weight or 100% by weight of the thermoplastic polyurethane described herein. The polishing layer may also comprise less than 1% by volume inorganic abrasive particles. Additional information regarding CMP polishing and articles is described in WO2022 / 249135; incorporated herein by reference. Examples Material Description Source EMI-24 Primarily 2-ethyl-4-methylimidazole, Evonik, Essen, Germany available under the trade designation “IMICURE EMI-24” Heloxy 8 Monoglycidyl ether containing alkyl Westlake, Houston, TX chains which are predominately C12 and C14 in length, available under the trade designation “HELOXY 8” 2- 2-Methylimidazole MilliporeSigma, Burlington, MA Methylimidazole Heloxy 61 Butyl glycidyl ether, available under Westlake, Houston, TX the trade designation “HELOXY 61” Epoxycyclohexane 1,2-Epoxycyclohexane Tokyo Chemical Industry Co., Portland, OR Ethylene Ethylene carbonate Thermo Scientific Chemicals, Waltham, carbonate MA Fomrez 44-160 Poly(butylene adipate) polyol with a Lanxess, Cologne, Germany hydroxy number of 160, available under the trade designation “FOMREZ 44-160” PTMEG 1000 Polytetramethylene ether glycol with BASF Corporation, Ludwigshafen, a hydroxl number of 112 available Germany from BASF as “POLYTHF 1000” PTMEG 650 Polytetramethylene ether glycol with BASF Corporation, Ludwigshafen, a hydroxl number of 173 available Germany from BASF as “POLYTHF 650” 1,4-BDO 1,4-Butanediol BASF Corporation, Ludwigshafen, Germany Decanol 1-Decanol Alfa Aesar, Haverhill, MA Rub 1234 MDI-based, low-functionality, Huntsman Corporation, The Woodlands, polyester-based prepolymer with TX 18.9% NCO, available under the trade designation “RUBINATE 1234” 4,4’-MDI Diphenylmethane 4,4’-diisocyanate Covestro, Leverkusen, Germany available under the trade designation “MONDUR MB” MLQ Mixture of 4,4'- and 2,4'- MDI with Covestro, Leverkusen, Germany 33.5% NCO, available under the trade designation “MONDUR MLQ” Des W Hydrogenated MDI with 31.8% NCO, Covestro, Leverkusen, Germany available under the trade designation “DESMODUR W” TEDA 1,4-Diazabicyclo[2.2.2]octane MilliporeSigma, Burlington, MA CHIM 944 Poly[[6-[(1,1,3,3- BASF Corporation, Ludwigshafen, tetramethylbutyl)amino]-1,3,5-triazin- Germany 2,4-iyl][(2,2,6,6-tetramethyl-4- piperidinyl)imino]-1,6- hexanediyl[(2,2,6,6-tetramethyl-4- piperidinyl)imino]]), with an MNof 2000-3100 g / mol, available under the trade designation “CHIMASSORB 944” Preparatory Example 1 1-dodecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol and 1-tetradecoxy-3-(2-ethyl-5-methyl- imidazol-1-yl)propan-2-ol EMI-24 (3.9 grams) and Heloxy 8 (10.1 grams) were added to a glass vial with a magnetic stirbar. They were stirred at room temperature for two hours, and then stirred in an 80°C oil bath for 1 hour. The resulting material was a viscous orange liquid. IR showed the loss of the peaks at 840 cm-1and 910-1consistent with conversion of the epoxy groups. Preparatory Example 2 1-butoxy-3-(2-methylimidazol-1-yl)propan-2-ol 2-methylimidazole (2.8 grams) and Heloxy 61 (5.2 grams) were added to a glass vial with a magnetic stirbar. They were stirred in an 80°C oil bath. After 6 minutes, the solid 2-methyl imidazole was no longer visible, and the mixture was a clear liquid. The sample was allowed to continue stirring with heat for 4 hours. The resulting material was a viscous orange liquid. IR showed the loss of the peak at 900 cm-1consistent with conversion of the epoxy groups. Preparatory Example 3 2-(2-ethyl-4-methyl-imidazol-1-yl)cyclohexanol EMI-24 (3.3 grams) and epoxycyclohexane (2.9 grams) were added to a glass vial with a magnetic stirbar. They were stirred in a 100°C oil bath for 2.5 hours. The resulting material was a viscous orange liquid.1H NMR analysis showed loss of the signal at 3.1 ppm consistent with conversion of the epoxy group. Preparatory Example 4 2-(2-ethyl-4-methyl-imidazol-1-yl)ethanol EMI-24 (5.0 grams) and ethylene carbonate (4.8 grams) were added to a 50 mL RBF with a magnetic stirbar. This was capped with a septum and purged with nitrogen. They were stirred in a 120°C oil bath for 3 hours.1H NMR analysis showed signals consistent with analysis published in Polym Int 2021; 70: 582–593. Preparatory Example 5 – Isocyanate Prepolymer of MDI and PTMEG Molten MDI monomer (50°C, 914 g) was placed in glass jar. Warm PTMEG 650 (100°C, 94 g) was added to the jar. The contents of the jar were stirred with overhead mixer for two hours while under a nitrogen purge. General Method for Microcompounder Polymerization and Characterization When the formulation included CHIM 944, the solid CHIM 944 was added to compounder one minute after the reactive liquid mixture had been added. The catalyst performance was semi-quantitatively characterized by recording the axial force over time as polyurethanes were polymerized in an MC15 microcompounder (Xplore Instruments, Sittard, Netherlands). The compositions shown in Table 1 were prepared in a plastic cup and mixed on a Dac 150 speed mixer (FlackTek, Landrum, SC) for 10 seconds at 3000 RPM.15 mL of the resulting reactive mixture was immediately transferred to a the microcompounder and mixed with a screw speed of 100 RPM for at least 5 minutes. The increase in axial force with time results from the viscosity increase of the mixture as polymerization occurs. Table 2 lists the times required to reach 50% of the maximum observed increase in axial force. This time to reach 50% force is designated as t(50%). Shorter values of t(50%) indicate faster polymerizations. Table 2 also lists the ratio of t(50%) for each example over the t(50%) value for an equivalent formulation with no added catalyst. This ratio is designated t(50%)ex / t(50%)ctrl. Smaller values of t(50%)ex / t(50%)ctrlindicate more significant polymerization acceleration. Table 1 – Formulation Components and Amounts (wt.%) Polyol Chai Mono mmol / Isocyanate / Amine Imidazole mmol / n Alcohol g Catalyst g Ext. (ratio*) Fomre PTME 1,4- Decano mmol / Rub Other CHI z G BDO l g 1234 Iso M 44-160 1000 944 CE 38.75 5.87 0.35 0.022 55.0 none 1 4 CE 38.79 5.86 0.36 0.023 54.9 TED 0.1 2 0 A 0 E1 39.19 5.74 0.13 0.008 54.3 PE1 0.5 0.014 9 4 (1.75) E2 39.08 5.80 0.13 0.008 54.6 PE2 0.2 0.014 9 9 (1.75) CE 49.69 9.77 0.40 0.025 40.14 none 3 MLK E3 49.63 9.80 0.25 0.016 40.15 PE3 0.1 0.009 MLQ 8 (1.78) E4 49.60 9.78 0.27 0.017 40.22 PE4 0.1 0.008 MLQ 3 (2.125) CE 39.50 11.44 0.51 0.032 48.55 none 4 Des W E5 39.52 11.44 48.56 PE4 0.4 0.032 Des 9 W CE 17.85 10.89 0.40 65.37 5.5 None 5 PE6 E6 18.60 10.75 0.025 64.29 5.5 PE1 1.0 0.025 PE6 0 (1) E7 23.97 10.33 64.70 PE1 1.0 0.025 PE6 0 *moles of hydroxy-functional imidazole / moles of monoalcohol Table 2 – Microcompounder Force Characterization Microcompounder t(50%) t(50%)ex / Temperature (seconds) t(50%)ctrlCE1 220 °C 147 1 CE2 220 °C 37 0.25 E1 220 °C 63 0.43 E2 220 °C 47 0.32 CE3 220 °C 186 1 E3 220 °C 35 0.19 E4 220 °C 43 0.23 CE4 210 °C 423 1 E5 210 °C 236 0.56 CE5 220 °C 64 1 E6 220 °C 33 0.52 E7 220 °C 31 0.58 Comparing CE1 (no catalyst) to CE2 (conventional amine catalyst), the reaction times show strong catalytic activity with the TEDA in CE2. However, the TEDA also causes loss of the force in the later stages of the processing which appears to correlate to degradation of the polymer molecular weight (Figure 1). Presumably, the TEDA is catalyzing an undesirable degradation reaction. In contrast E1 and E2 can be compared to CE1, and they show significant catalytic activity without causing substantial degradation of force in the later stages of processing. E3 shows similar performance in a polyurethane system using a different isocyanate and a different polyol. Compared to the uncatalyzed control sample (CE3), E3 shows significant catalytic activity while still producing a stable force in late stages of processing. E5 and CE4 demonstrate the performance of this type of catalyst in a polyurethane system with an aliphatic isocyanate, which is known to be less reactive than the aromatic isocyanates used in the preceding examples. The reaction with E6 was much slower that the examples with aromatic isocyanate, but it did show an acceleration in force development compared to the control experiment with no catalyst (CE4). Melt Viscosity Measurement The melt viscosity was measured using a DHR-2 rheometer (TA Instruments, New Castle, DE). A disk of polymer between 0.8 and 1.8 mm thick having a diameter of 8 mm was dried in a 70 °C oven. The sample was mounted in the rheometer with 8 mm diameter parallel plates. The sample was tested using a temperature ramp from 150 °C to 210 °C with oscillations of 1% strain and angular frequency of 1.0 rad / s. The complex viscosity and tan delta values at specified melt temperatures are reported in Table 3. Size Exclusion Chromatography (SEC) Samples of polymer were dissolved in tetrahydrofuran at a concentration of 5 mg / g and then subjected to SEC analysis. The SEC equipment consisted of a 1260 Infinity II liquid chromatography system (comprised of isocratic pump, autosampler, column compartment and variable wavelength UV / vis detector) from Agilent Technologies (Santa Clara, CA) operated at a flow rate of 1.0 mL / minute. The SEC column set was comprised of two PLgel 5 um MIXED-C (300 millimeter (mm) length x 7.5 mm internal diameter) and a PLgel 5 um guard column (50 millimeter (mm) length x 7.5 mm internal diameter) all from Agilent Technologies. The detection consisted of a miniDAWN 3 angle Light Scattering detector and an OPTILAB differential refractive index detector, both from Wyatt Technology Corporation (Santa Barbara, CA). Data were collected and analyzed using software ASTRA version 8 from Wyatt Technology Corporation. The column compartment, UV / vis detector, and differential refractive index detector were set to 40 °C. The solvent and eluent (or mobile phase) consisted of tetrahydrofuran (stabilized with 250 parts per million of butylated hydroxytoluene) OMNISOLV grade from EMD Millipore Corporation, Burlington, MA. Table 3 – Melt Viscosity and Molecular Weight Complex Tan delta Temperature MNMWViscosity (°C) (cPs) CE1 9,840,00 1.92 200 CE2 44,000 3.81 200 E1 10,700,000 1.59 200 E2 6,610,000 2.07 200 CE3 10,500,000 2.19 160 53,000 149,000 E3 3,730,000 4.71 160 42,000 96,000 E4 880,000 17.2 160 30,000 65,000 E5 4,309,000 5.40 190 CE5 2,870,000 3.42 195 E6 1,790,000 4.16 195 E7 1,780,000 1.32 195

Claims

What is claimed is:

1. An article comprising a thermoplastic polyurethane, wherein the thermoplastic polyurethane is the reaction product of a mixture comprising: a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; d) at least one hydroxy-functional imidazole compound; and at least one of the following: e) a mono-alcohol, f) a reactive compound that comprises hindered amine groups, or a combination of e) and f).

2. The article of claim 1 wherein the article is a film, a structured film, a polishing layer, a molded component, or fibers.

3. The article of claims 1-2 wherein the mono-alcohol is a fatty alcohol.

4. The article of claims 1-3 wherein the at least one hydroxy-functional imidazole compound is selected from: 1-dodecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol; 1-tetradecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol; 1-butoxy-3-(2-methylimidazol-1-yl)propan-2-ol; 2-(2-ethyl-4-methyl-imidazol-1-yl)cyclohexanol; 2-(2-ethyl-4-methyl-imidazol-1-yl)ethanol; and.

5. The article of claims 1-4, wherein the diisocyanate comprises aromatic groups.

6. The article of claims 1-5 wherein the mixture further comprises C1-C20 diol.

7. The article of claims 1-6 wherein the at least one hydroxy-functional imidazole compound and mono- alcohol, when present, end caps the polyurethane chains.

8. The article of claims 1-7 wherein the molar ratio of hydroxy-functional imidazole compound to mono- alcohol ranges from 0.1 to 10.

9. An article comprising a thermoplastic polyurethane wherein the thermoplastic polyurethane is the reaction product of a mixture comprising: a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; d) one or more hydroxy-functional imidazole compounds; wherein the thermoplastic polyurethane of the article is substantially free of dienophile moieties or the reaction product thereof.

10. The article of claim 9 wherein the thermoplastic polyurethane is further characterized by claims 2-6.

11. The article of claims 1-10 wherein the polishing layer comprises a working surface that includes a land region and a plurality of pores and / or a plurality of asperities.

12. The article of claim 11 wherein the polishing layer further comprises a plurality of independent or interconnected macrochannels.

13. The article of claims 11-12 wherein the polishing layer includes less than 1% by volume inorganic abrasive particles.

14. The article of claims 11-13 wherein the polishing layer is disposed on the surface of a polishing pad.

15. The article of claim 14 wherein the polishing pad comprises foam.

16. A thermoplastic polyurethane comprising the reaction product of a mixture comprising: a) at least one diol, b) at least one diisocyanate; c) optionally a diol chain extender; d) at least one hydroxy-functional imidazole compound; and at least one of the following: e) a mono-alcohol, f) a reactive compound that comprises hindered amine groups, or a combination of e) and f).

17. The thermoplastic polyurethane of claim 16 further characterized by claims 2-8.

18. A hydroxy-functional imidazole compound consisting of 1-dodecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol, 1-tetradecoxy-3-(2-ethyl-5-methyl-imidazol-1-yl)propan-2-ol, and combinations thereof.

19. A method of making a thermoplastic polyurethane article comprising: providing a thermoplastic polyurethane according to claims 1-16; and forming the thermoplastic composition into an article at an elevated temperature; and cooling the article.

20. The method of claim 19 wherein the components are combined and reacted within an extruder at a temperature in the range of 150-220°C.

21. The method of claims 19-20 wherein the extruder conveys information about the axial force and the reaction attains half a peak axial force in a shorter duration of time than the same reaction lacking the hydroxy-functional imidazole compound.

22. The method of claim 21 wherein a ratio of the time to reach a half peak axial force of the reaction to the same reaction lacking the hydroxy-functional imidazole compound is less than 0.75, 0.50, or 0.

25.

23. The method of claims 19-22 wherein axial force reaches a plateau in an amount of time less than the same reaction lacking the hydroxy-functional imidazole compound.

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