Patent ID: 8389667

Claim:
Partially crystalline polyethyleneterephthalate having a degree of polymerization larger than 80 manufactured from (a) diol component which comprises up to 95 mol % to 100 mol % of ethylene glycol, and (b) a dicarboxylic acid component which up to 95 mol % to 100 mol % comprises terephthalic acid, wherein a total comonomer content of said polyethyleneterephthalate lies between 1 and 7%, and wherein in a first step the diol component and dicarboxylic acid component are brought together in a liquid phase to obtain a low viscosity prepolymer having a degree of polymerization between 10 and 50, said prepolymer is thereafter granulated into granules having an average granule size between 0.2 and 3 mm, and the granules subjected to a solid phase polycondensation at a temperature below 220° C. for from 6 to 30 hours to obtain a polyethyleneterephthalate, wherein a DSC melting point of said polyethyleneterephthalate measured at a heat-up rate of 10° C./min in a first run-through and in a second run-through, lies below a comonomer dependent melting temperature (Tm) of a polyethyleneterephthalate having been prepared via a solid state polycondensation from a prepolymer having a degree of polymerization between 65 and 80 which was formed into granulate having a mass of 10 to 30 mg and which was cooled with water below its glass transition temperature, as calculated with the equation T 0 − 2 . 5 ° C.*% comonomer content (in mol %) with T 0 being equal to 260° C., wherein a comonomer proportion of the diol component is comprised mainly of diethyleneglycol, or as calculated with the equation T 0 − 3 . 0 ° C.*% comonomer content (in mol %) with T 0 being equal to 260° C.