Continous polymerization method of laurolactam and apparatus therefor

摘要

A continuous polymerization method for laurolactam which has three stages. A prepolymerization process include steps of preliminarily heating laurolactam with 1 to 10% weight of water added, thereafter continuously feeding and passing the laurolactam from the upper part of the lower part of the longitudinal-type polymerization reaction zone, arranging a temperature decreasing gradient of 10 DEG C. or more than the upper part to the lower part directions at a polymerization temperature of 250 DEG and 300 DEG C. in the polymerization zone, and polymerizing the laurolactam under vapor pressure up to a conversion rate of 99.5% or more. A intermediate process has a step of releasing pressure from the prepolymerization product from the prepolymerization process for conversion into an intermediate product at atmospheric pressure. A post polymerization process includes the steps of continuously feeding the intermediate product at atmospheric pressure from the intermediate process in the direction from one end of the lower end to the other lower end of the traverse-type polymerization zone, polymerizing the intermediate product with agitation and air discharge in the presence of inert gas under reduced pressure or atmospheric pressure to a final relative viscosity of eta tau of 1.9 to 3.3.