PRODUCTION OF NYLON RESIN AND PRODUCTION OF NYLON RESIN COMPOSITION

摘要

PROBLEM TO BE SOLVED: To produce a high-quality resin at a high efficiency and a low energy cost by producing a nylon resin having a terminal group concentration in a specified range and removing monomers and oligomers from the nylon resin by using a vertically agitated thin-film evaporator. SOLUTION: Nylon-forming materials are polymerized to produce a nylon resin having a degree of polymerization of 1.0-3.5 (as measured in a 0.01 g/ml sulfuric acid solution at 25 deg.C), a terminal amino concentration and a terminal carboxyl concentration each in the range of 1×10-5 to 12×10-5 mol/g and satisfying the relationships: terminal amino concentration < (terminal carboxyl concentration-0.02×10-5 mol/g). This resin is fed into a vertical agitator-equipped thin-film evaporator and passed through it at a temperature of the melting point of the nylon resin to 400 deg.C and a pressure of 0.01-700 mmHg in an atmosphere having an oxygen concentration of 500 ppm or below to evaporate and remove the monomers and the oligomers from the nylon resin. The molten resin after the evaporation treatment is extruded, and the extrudate is pelletized to obtain nylon resin pellets.