Thermoplastic composition containing a mold release agent which is based on an ester of di- or polyglycerols and at least one carboxylic acid

A method for producing a thermoplastic composition comprising

• a) a thermoplastic polyester as thermoplastic polymer selected from polyethylene terephthalates, polyalkylene naphthalates, polyalkylene dibenzoates or mixtures of at least two of these thermoplastic polyesters,
• b) a mold release agent, and
• c) optionally further additives,
• comprising the method steps:
• i) providing a thermoplastic polymer or a precursor of a thermoplastic polymer or both;
• ii) providing the mold release agent containing an ester, based on
• an alcohol component based on two or more glycerol units, the alcohol component being selected from a diglycerol, a triglycerol or a tetraglycerol or at least two thereof;
• and
• at least one carboxylic acid or a derivative of a carboxylic acid or both, the carboxylic acid or the derivative of a carboxylic acid comprising a number of carbon atoms in a range of from 6 to 26;
• iii) optionally providing further additives;
• iv) mixing components i), ii) and optionally iii);
• and
• wherein a metal catalyst which is a high-temperature catalyst is used during esterification wherein the high-temperature catalyst achieves full activity at temperatures above 180° C.;
• and
• wherein a saturated, α-olefin oligomer of at least one C6-C18 α-olefin is used in at most an amount such that the thermoplastic composition obtained by mixing components a) to c) comprises less than 0.001% by weight of the saturated, α-olefin oligomer of at least one C6-C18 α-olefin.