Polytrimethylene terephthalate having a low level of acrolein and a process for producing the same

Abstract

The present invention provides a process of reducing acrolein byproduct from polytrimethylene terephthalate using selected phosphorous compounds to contact the polytrimethylene terephthalate or reactants in the process of producing polytrimethylene terephthalate. The selected phosphorous compounds are retained in the polytrimethylene terephthalate. The present invention also provides polytrimethylene terephthalate compositions containing amounts of phosphorous compounds.

1 . Polytrimethylene terephthalate containing from about 1 to about 100 ppm of phosphorous, based on the total amount of polytrimethylene terephthalate, in the form of a phosphorous compound which has reacted with the polytrimethylene terephthalate wherein said phosphorous compound is selected from a group of phosphorous compounds consisting of a phosphorous compound of formula I, a phosphorus compound of formula II, a phosphorous compound of formula III, a phosphorous compound of formula IV, a phosphorus compound containing an aromatic acid, a phosphite containing a hydroxyalkyl group, carboxyethyl phosphonic acid and its corresponding esters with 1,3-propanediol, triethyl-3-phosphonopropionate, 3-hydroxypropyl phosphonoacetate, 3-hydroxypropyl phosphate, and tetraethyl methylenediphosphonate wherein formula I is
   A-O—B—O—C  (I)   wherein A is a phosphate, phosphonate, or phosphite moiety, B is the residuum of 1,3-propanediol, and C is hydrogen or a carboxylate ester moiety;   formula II is
   Y—O—R′—O-Z  (II) 
   wherein Y is a phosphate, phosphonate, or phosphite moiety, R′ is the residuum of an aliphatic glycol having from 2 to 12 carbon atoms, and Z is hydrogen or a carboxylate ester moiety;   formula III is   
       
         
           
           
               
               
           
         
         wherein R is an aliphatic group having 1-12 carbons, and R 1  and R 2 , independently, are hydrogen or an alkyl or aryl moiety having 1-20 carbons; and 
         wherein formula IV is 
       
       
         
           
           
               
               
           
         
         wherein R and R′, independently, are aliphatic moieties having 1-12 carbons. 
       
     
     
         21 . The polytrimethylene terephthalate of claim  20  wherein Y of formula II is a phosphonocarboxylate of formula V 
       
         
           
           
               
               
           
         
         wherein R is a divalent aliphatic group having from 1 to 20 carbon atoms or a divalent aromatic group having at least 5 carbon atoms, R 1  and R 2  are each, independently, hydrogen or C 1  to C 20  alkyl or aryl. 
       
     
     
         2 . The polytrimethylene terephthalate of  claim 1  wherein the phosphorous compound containing an aromatic acid is selected from the group consisting of: 
       
         
           
           
               
               
           
         
         where R is an aliphatic group containing 1 to 12 carbon atoms. 
       
     
     
         3 . The polytrimethylene terephthalate of  claim 1  containing less than about 20 parts per million acrolein. 
     
     
         4 . A method for producing a polytrimethylene terephthalate yarn comprising melt-spinning the polytrimethylene terephthalate of  claim 1 . 
     
     
         5 . Polytrimethylene terephthalate with an acrolein content of less than about 20 ppm, and intrinsic viscosity of about 0.7 to about 1.2 dl/g, Hunter color values of L greater than about 75 and b less than about 5, a phosphorous content of from 5 to 50 ppm, and a filter value of less than about 30 bar·cm 2 /kg.