Rapid crystallizing poly(trimethylene terephthalate) compositions and processes

摘要

Small amounts of one or more alkali or alkaline earth metal salts, particularly lithium or calcium salts, added to polytrimethylene terephthalate (PTT) have been found to greatly accelerate the crystallization rate of the polymer. Preferably, from about 1 to about 10 ppm of the alkali or alkaline earth metal, based on metal, is effective. For example, 7 ppm of Li⁺ can produce about 5-20 times faster crystallization, depending on the rate of cooling, compared to PTT without lithium. The rapid-crystallizing PTT compositions are preferably comprised of carboxylate salt endgroups, COOM, wherein M is an alkali or alkaline earth metal cation, preferably lithium or calcium cation. The metal salt is conveniently added to the polymerization process.