Patent ID: 8124686

Claim:
A process for the preparation of polyamide-12 powder to obtain a polyamide-12 powder with a melting point of 183±1° C. comprising polymerizing a lauryllactam solvent solution by anionic polymerization, the polyamide-12 powder being insoluble in said solvent, the said polymerization being carried out: in the presence of a catalyst and of an activator, wherein the ratio of the catalyst to the activator in moles is between 0.8 and 1.2; in the presence of a finely divided organic or inorganic filler, the proportion of this filler being 0.35 to 0.9 g per 1000 g of lauryllactam; and in the presence of an amide of formula R 1 —NH—CO—R 2 in which R 1 can be an R 3 —CO—NH—, an R 3 —CO—NH—CH 2 CH 2 — or R 3 —O— radical and in which R 1 , R 2 and R 3 denote an aryl, alkyl or cycloalkyl radical, the proportion of this compound being between 0.001 mol and 0.030 mol per 1000 g of lauryllactam wherein said powder has a mean diameter of between 15 microns and 100 microns; a melting point of 183±1° C.; has a crystallization temperature of 135±1° C.; and wherein the proportion of catalyst to lauryllactam is from 0.1 to 5 mol per 100 mol of lauryllactam.