Abstract: This invention relates to polyalkylene terephthalates which crystallize rapidly, and process of making such compositions and a process of using such compositions in injection molding. The compositions comprise polyalkylene terephthalates with intrinsic viscosities in excess of about 0.4 dl/g in 1:1 phenol/tetrachloroethane at 25.degree. C. and at least about 0.5 wt. %, based on the weight of resin and additive, of an aromatic carboxylic acid ester. These compositions may be prepared by intimately mixing the ingredients, for example by extrusion. These compositions, particularly those wherein the polyester consists essentially of polyethylene terephthalate, may be injection molded with mold temperatures less than about 120.degree. C. and still retain a significant degree of crystallinity even with short mold residence times.

Abstract: Polyethylene terephthalate copolymers comprising (I) blocksegments having a glass transition temperature below 0.degree. C. and (II) polyethylene terephthalate segments modified with certain diols having 3 to 10 carbon atoms, have an excellent rate of crystallization and necessitate mould temperatures of below 100.degree. C.

Abstract: Polyalkylene terephthalates containing 0.5-30% by weight of oligomeric carboxylic acid polyesters have a higher crystallization speed and thus allow lower mold temperatures and shorter injection cycles. The polyalkylene terephthalates generally have intrinsic viscosities in excess of about 0.4 dl/g in 1:1 phenol tetrachloroethane at 25.degree. C. and are at least about 90 mol % terephthalic acid based. The oligomer additive is based on carboxylic acids, with sebacic and adipic being preferred, and aliphatic, cycloaliphatic or araliphatic dihydric alcohols. This additive has a minimum polymerization degree of 2 and a maximum number-average molecular weight of about 6000.Faster crystallization rates can be imparted to polyalkylene terephthalates by mixing them with the ester additive and melt homogenizing the mixture.

Abstract: The current invention is concerned with block copolyesters of low glass transition temperature segments and ethylene glycol based polyester segments linked together by carboxylic acid ester groups and special diols, and a process for preparing these copolyesters. These copolyesters display molded resin properties similar to polyethylene terephthalate but crystallization behavior similar to polybutylene terephthalate, i.e. they have high strength and superior solvent resistance, but they also crystallize rapidly. They are made by subjecting low glass transition temperature (less than 0.degree. C.) polymers with carboxyl, hydroxyl or reactive ester end groups to esterification or transesterification conditions with ethylene glycol based polyester segments having a minimum intrinsic viscosity of 0.2 dl/g and special diols having four to ten carbon atoms with 3 or 4 carbon atoms between the hydroxyl groups in the presence of appropriate catalysts.

Abstract: The present invention is concerned with thermoplastic terephthalic acid copolyesters which crystallize more rapidly than homopolyethylene terephthalate and are based on a diol component which is about 98 to 99.9 mol % of ethylene glycol and the balance 2-ethylhexane-1,3-diol. The acid component may be up to about 10.0 mol % of other than terephthalic acid or its dimethyl ester.This invention is also concerned with a process of synthesizing such copolyesters by esterifying or transesterifying the acid and diol components between about 150.degree. and 250.degree. C. in the presence of appropriate catalysts. The condensation product may be subject to polycondensation at about 200.degree. to 300.degree. C. under reduced pressure in the presence of esterification catalysts. In a preferred embodiment the 2-ethylhexane-1,3-diol is added after the initial reaction between the acid component and the ethylene glycol and preferably after the degree of polycondensation is greater than 4.

Abstract: The present invention is concerned with polyalkylene terephthalate molding compositions which have improved crystallization behavior as a result of blending with selected sulphonic acid esters. The addition of an effective amount of these esters, generally between about 0.5 to 30 wt. %, improves the rate of crystallization of polyalkylene terephthalates such as polyethylene terephthalate thus permitting the use of shorter mold residence and lower mold temperatures in injection molding.The invention is also concerned with a process for improving the crystallization behavior of polyalkylene terephthalates by melt blending them with selected sulphonic acid esters.

Abstract: Terephthalic copolyesters, the diol component of which consists of ethylene glycol and 2.2-diethyl propane-1.3-diol crystallize more rapidly than pure polyethylene terephthalate and can be molded in a way comparable to butylene terephthalate.

Abstract: A process for the production of high molecular weight low color polyethylene terephthalates using a particulaarly effective polycondensation catalyst is disclosed. Titanium tetrabutylate is added to the reaction mixture after the initial esterification or transesterification reaction is about 95% complete and the polycondensation is completed at temperatures between about 200 and 270.degree. C under reduced pressure. Metaphosphoric acid or its alkali or alkaline earth metal salts are added with the titanium tertrabutylate to control the color. Commonly accepted catalysts may be employed for the initial esterification or transesterification. Polymers with intrinsic viscosities in excess of 0.7 dl/g and yellowness numbers less than 6 can be produced.

Abstract: Terephthalic copolyesters, the diol component of which mainly consists of ethylene glycol units, crystallize more rapidly than pure polyethylene terephthalate and can be moulded in a way comparable to polybutylene terephthalate.

Abstract: Terephthalic copolyesters, the diol component of which mainly consists of ethylene glycol units, crystallize more rapidly than pure polyethylene terephthalate and can be moulded in a way comparable to polybutylene terephthalate.