GB1089360A - A process for the continuous polymerisation of lactams in moulds - Google Patents

Abstract

<PICT:1089360/C3/1> <PICT:1089360/C3/2> Lactams are continuously polymerized by a base catalysed reaction and simultaneously shaped into continuous articles by filling a continuous mould with fused lactam containing a catalyst and activator as it moves through a feed zone and removing the moulding formed, from the mould when polymerization is completed. Lactams specified are those having more than 6 ring atoms, including caprolactam and caprylactam and mixtures thereof. Catalysts and activators specified include the Na and K salts of caprolactam, 1,6-bis(caprolactam - N - carbamino)-hexane and trimethylcyclobuta-1,3-dione. The lactam melt may also contain regulators to lower the M.W. of the polymer, fillers, dyes, expanding agents, cross - linking agents, e.g. dilactams and triisocyanates, plasticizers and glass fibres. In embodiments shown in Figs. 1 and 2 a mixture of lactam and catalyst is prepared in (1); a mixture of lactam and activator is prepared in (2) and the two are mixed in (5). In Fig. 1 the melt is fed at (6) into a continuous mould bounded by belts (7) and (9). (11) is a plastic strip, e.g. polyethylene or ethylene/propylene copolymer which seals the joint between the belts. The moulded melt is compressed by rollers (12) and heated by heaters (8) before emerging as a shaped article at the other end of the apparatus. In Fig. 2 the melt is fed at (6) into a mould bounded by drum (7), belt (8) and sealing strip (12). The surface of the drum is profiled, the surface either being of the same material as the drum or of plastic or another metal. Belt (8) is pressed on to the drum by rollers (9) and (9a). The processes may be carried out in the absence of air and water using a N2 or argon atmosphere. The melt may be heated by infra-red radiation, steam, a liquid jacket, or hot air to a temperature between the melting points of the monomer and polymer. The product leaving the mould may still be plastic and may subsequently be reshaped, tempered, stretched, granulated, injection-moulded, or extruded to make tapes, films, filaments and driving belts.