Polyamide prepolymer and polyamide, and method for producing them

摘要

A method for producing a polyamide prepolymer including heating an aqueous solution of caprolactam having a water content of from 2 to 20% by weight, under pressure at a temperature of from 200 to 330° C. for 1 to 30 minutes, to produce polyamide prepolymer having an amino end group content of at least 0.1 mmol/g and a cyclic oligomer content of at most 0.6% by weight, and a conversion at most 40% by weight.