Abstract: The pelletized product of melt condensation polymerization of 1,3-propanediol and terephthalic acid is crystallized in a vessel designed for continuous fluidized bed flow of the pellets in water at a temperature within the range of about 65 to about 100° C. Hot-water treatment in the vessel permits crystallization of the pellets in a continuous operation and results in an increase of the crystallinity of the polymer to greater than about 35% and an increase in pellet density.

Abstract: The present invention is a process for producing poly(trimethylene terephthalate) (PTT) at an increased solid state polymerization rate, wherein 1,3-propane diol and an aromatic acid or a dialkyl ester thereof are esterified or transesterified, the esterification or transesterification product is polycondensed, and the polycondensation product is pelletized and then subjected to continuous solid state polymerization at a temperature of 200 to 225° C., preferably 210 to 225° C. In one embodiment of the present invention, the temperature range is 200 to 220° C., and the pellet size of the polymer to be solid state polymerized is from 1.0 to 1.5 g/100. In another embodiment of the present invention, the solid state polymerization is carried out at 210 to 225° C. for from 1 to 20 hours and then the temperature is increased to above the initial melting point of the polymer to produce a PTT polymer with an intrinsic viscosity of 1.3 dl/g or greater.

Abstract: The present invention is a process for producing poly(trimethylene terephthalate) (PTT) at an increased solid state polymerization rate, wherein 1,3-propane diol and an aromatic acid or a dialkyl ester thereof are esterified or transesterified, the esterification or transesterification product is polycondensed, and the polycondensation product is pelletized and then subjected to continuous solid state polymerization at a temperature of 200 to 225° C., preferably 210 to 225° C. In one embodiment of the present invention, the temperature range is 200 to 220° C., and the pellet size of the polymer to be solid state polymerized is from 1.0 to 1.5 g/100. In another embodiment of the present invention, the solid state polymerization is carried out at 210 to 225° C. for from 1 to 20 hours and then the temperature is increased to above the initial melting point of the polymer to produce a PTT polymer with an intrinsic viscosity of 1.3 dl/g or greater.

Abstract: The pelletized product of melt condensation polymerization of 1,3-propanediol and terephthalic acid (or alkyl ester thereof) is crystallized by immersion in water at a temperature within the range of 60 to about 100° C. Hot-water treatment increases the crystallinity of the polymer to at least about 35% and increases pellet density to about 1.33 g/cm3.