Patent ID: 7381787

Claim:
A process of reducing acrolein byproduct from polytrimethylene terephthalate, comprising contacting a phosphorus compound selected from the group consisting of a phosphorous compound of formula I, a phosphorous compound of formula II, a phosphorous compound of formula III, a phosphorous compound of formula IV, a phosphorous compound containing an aromatic acid, a phosphate 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 with a) 1,3-propanediol, terephthalic acid, and/or polytrimethylene terephthalate in a process of producing polytrimethylene terephthalate; or b) 1,3-propanediol, dimethylterephthalate, and/or polytrimethylene terephthalate in a process of producing polytrimethylene terephthalate; or c) molten polytrimethylene terephthalate to produce polytrimethylene terephthalate, wherein at least 1 ppm of phosphorous, based on the total amount of polytrimethylene terephthalate, is retained in the polytrimethylene terephthalate; at least about 70% by weight of the phosphorus in the phosphorus compound is retained in the polytrimethylene terephthalate; and the amount of acrolein in the polytrimethylene terephthalate is decreased; 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.