METHOD OF PREPARING CAPROLACTAM BY DEPOLYMERIZATION OF MIXTURES WHICH COMPRISE POLYMERS OF MOLDED THERMOPLASTIC MATERIALS Russian patent published in 2000 - IPC

FIELD: chemistry of polymer. SUBSTANCE: caprolactam is prepared from mixtures which comprise polymers or molded thermoplastic materials by depolymerization at elevated temperatures in the presence of water. Original mixtures consist of 50-99.9 wt % of polymer or molded thermoplastic material having recurring unit -[-N(H)-(CH₂)₅-C(O)-]; 0.1-50 wt % of additives selected from group consisting of inorganic fillers, organic or inorganic pigments and colorants; 0-10 wt % of organic and inorganic additives; 0-40 wt % of polyamide-free polymers and 0-20 wt % of polyamides except for polycaprolactam and copolyamides prepared from caprolactam. Depolymerization is carried out at temperatures from 270 to 350 C, at water to polymer or molded thermoplastic material weight ratio from 1:1 to 20:1 and reaction time from 0.25 to 3 hours to prepare caprolactam with high yield from waste, and utilization thereof is solved. EFFECT: more efficient preparation method. 2 cl, 8 ex, 1 tbl