Powdered polyamide prodn. - by dissolving polyamide granules, which have been extracted with dimethyl formamide, in dimethyl formamide and cooling the soln.

摘要

Polyamides having =10 aliphatic C atoms per -CONH- gp. or mixed polyamides contg. =70 wt. % of such components are obtd. in powder form by cooling a soln. of the polyamide in diemthylformamide (DMF) and opt. grinding the pptd. prod. The polyamide in granular form is first purified by extn. with DMF at 70-100 degrees C. Previous method of purification (removal of unchanged monomer and low mol. wt. by-prods) was by extn. with H2O, 1-4C alcohols and opt. benzene or toluene. This involved removal of extracting solvent and drying before final soln. and pptn. New process is simpler and saves considerable time.