Process for the production of polyamide compositions for moulding

摘要

Preparation of polyamide molding composition by (a) addition and dissolution of a solution of m-xylenediamine and dicarboxylic acid with water and additives to a dissolver and preparation of a mixture; (b) polycondensation of the mixture in a reaction vessel; (c) granulation of the polycondensate; and (d) drying of the granulate is new. A process for preparation of polyamide molding composition involving the following steps: (a) addition and dissolution of a solution of m-xylenediamine and dicarboxylic acid, which includes adipic acid and aromatic dicarboxylc acids, with water and additives to a dissolver and preparation of a mixture, where the sum of the added aromatic dicarboxylic acids is 2-15 mole% (relative to the added dicarboxylic acids); (b) polycondensation of the mixture in a reaction vessel; (c) granulation of the polycondensate; and (d) drying of the granulate. The maximum polycondensation pressure is 10 bar and the temperature is 255-270 degrees C, where the pressure is produced on heating the reaction mixture to the above temperature range, and immediately after the mixture has reached the maximum temperature, the pressure is decreased to less than 800 mbar while holding the mixture within the above temperature range, and the granulate is subjected to under water crystallization before dry ing. An Independent claim is included for a granulate obtained as above.