Abstract: This invention relates to a continuous process for production of poly(trimethylene terephthalate), wherein gaseous 1,3-propanediol by product resulting from the process is condensed in a condenser, and a portion of the condensed by-product is recycled back into the process.

Abstract: This invention relates to a continuous process for production of poly(trimethylene terephthalate), wherein gaseous 1,3-propanediol by-product resulting from the process is condensed in a condenser, the total amount of any trimethylene terephthalate cyclic dimer and poly(trimethylene terephthalate) in the condensed by-product 1,3-propanediol is adjusted, and a portion of the condensed by-product is recycled to the condenser while another portion is recycled back into the process.

Abstract: A continuous process for the production of poly(trimethylene terephthalate) is disclosed. According to the process, a liquid feed mixture comprising bis-3-hydroxypropyl terephthalate and/or low molecular weight polyesters of 1,3-propanediol and terephthalic acid, the liquid feed mixture having a mole ratio of propylene groups to terephthalate groups of 1.1 to 2.2 is fed to a flasher. A first stream of gaseous by-products is continuously vaporized and removed from the flasher, and a liquid flasher reaction product having a mole ratio of propylene groups to terephthalate groups of less than about 1.5 is continuously withdrawn from the flasher. The liquid flasher reaction product is continuously fed to a prepolymerizer where it is continuously polymerized to form a poly(trimethylene terephthalate) prepolymer and a second stream of gaseous by-products.