Titanium-based catalyst showing excellent activity and selectivity in polycondensation reactions

Abstract

A polycondensation reaction mixture is disclosed which includes a catalyst, acyclic esters, ethylene glycol, and water. The catalyst is a titanium atrane. The polycondensation reaction mixture is prepared by the steps of (a) contacting a solution comprising a titanium (IV) alkoxide compound and a first solvent with an organic acid; (b) contacting the solution formed in step (a) with a substituted or unsubstituted trialkanolamine to form an impure catalyst; (c) purifying the impure catalyst to form the titanium atrane catalyst; and (d) bringing the catalyst into contact with the acyclic esters under conditions that produce the ethylene glycol and water.

What is claimed is: 
     
         1 . A polycondensation reaction mixture, comprising:
 a catalyst comprising a titanium atrane, wherein the catalyst has a structure:   
       
         
           
           
               
               
           
         
       
       wherein R is H, C 1 -C26-alkyl-, aryl-, or hetaryl ; R 1  is H, or methyl-, or ethyl- or ethenyl- aryl, or hetaryl; R 2  is H, or methyl-, or ethyl, or ethenyl- aryl, or hetaryl and R 3  is H, or methyl- or ethyl-, or ethenyl-aryl, hetaryl;
 acyclic esters; 
 ethylene glycol; and 
 water. 
 
     
     
         2 . A method for making the polycondensation reaction mixture according to  claim 1  comprising: (a) contacting a solution comprising a titanium (IV) alkoxide compound and a first solvent with an organic acid; (b) contacting the solution formed in step (a) with a substituted or unsubstituted trialkanolamine to form an impure catalyst; (c) purifying the impure catalyst to form the titanium atrane catalyst; and (d) bringing the catalyst into contact with the acyclic esters under conditions that produce the ethylene glycol and water. 
     
     
         3 . The method according to  claim 2 , wherein the titanium (IV) alkoxide compound is titanium n-butylate, titanium isopropylate, titanium n-propylate, titanium t-buylate, or titanium ethylate. 
     
     
         4 . The method according to  claim 3 , wherein the first solvent is a primary alcohol, a secondary alcohol, or a tertiary alcohol. 
     
     
         5 . The method according to  claim 4 , wherein the organic acid is a carboxylic acid. 
     
     
         6 . The method according to  claim 5 , wherein the organic acid is acetic acid or propionic acid. 
     
     
         7 . The method according to  claim 6 , wherein the trialkanolamine is triethanolamine, triisopropanolamine, or a substituted triethanolamine. 
     
     
         8 . The method according to  claim 2 , wherein step (c) further comprises: c1) evaporating the first solvent from the impure catalyst to remove undesired byproducts; c2) contacting the product from step c1 with a second solvent to form a suspended solid; and c3) boiling the suspended solid to form a purified titanium atrane catalyst. 
     
     
         9 . The method according to  claim 8 , wherein the second solvent in step c2 is selected from the group consisting of toluene, alkyl substituted aromatics and long chain alkanes. 
     
     
         10 . The polycondensation reaction mixture according to  claim 1 , wherein the acyclic esters are produced by esterification of a polyacid and a polyol. 
     
     
         11 . The polycondensation reaction mixture according to  claim 10 , wherein the polyacid is selected from the group consisting of terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, and naphthalenedicarboxylic acid. 
     
     
         12 . The polycondensation reaction mixture according to  claim 10 , wherein the polyacid is a long-chain branching polyacid. 
     
     
         13 . The polycondensation reaction mixture according to  claim 12 , wherein the long-chain branching polyacid is selected from the group consisting of trimellitic acid and its anhydride. 
     
     
         14 . The polycondensation reaction mixture according to  claim 1 , wherein the polyol is selected from the group consisting of ethylene glycol, diethylene glycol, cyclohexanedimethanol, 1,3-propanediol, 2,2-dimethylpropanediol-1,3,1,4-butanediol, isosorbide. 
     
     
         15 . The polycondensation reaction mixture according to  claim 10 , wherein the polyol is an aromatic polyol. 
     
     
         16 . The polycondensation reaction mixture according to  claim 15 , wherein the aromatic polyol is selected from the group consisting of resorcinol, and hydroquinone. 
     
     
         17 . The polycondensation reaction mixture according to  claim 10 , wherein the polyol is a long-chain branching polyol. 
     
     
         18 . The polycondensation reaction mixture according to  claim 17 , wherein the long-chain branching polyol is selected from the group consisting of trimethylolpropane and pentaerythritol 
     
     
         19 . The polycondensation reaction mixture according to  claim 10 , wherein the polyacid is terephthalic acid and the polyol is ethylene glycol. 
     
     
         20 . The polycondensation reaction mixture according to  claim 1 , wherein the catalyst is present in a concentration of from 5 to 250 ppm. 
     
     
         21 . A method for producing polyester comprising providing the reaction mixture according to  claim 1  under conditions that polymerize the acyclic esters by way of polycondensation to form an acyclic polyester. 
     
     
         22 . The method according to  claim 21 , wherein the polycondensation comprises a melt phase conducted at a temperature of from 260° C. to 290° C. and a solid state phase conducted at a temperature of from 190° C. to 230° C. 
     
     
         23 . The method according to  claim 21 , wherein the polycondensation is conducted at a pressure of from 3.0 to 0.1 mbar.