Recycling polyurethane (foam) scrap - by swelling scrap and processing to give flowable gel particulate, adjusting hydroxy number of prod. and reacting with e.g. di:isocyanate

摘要

Recycling of solid or porous (e.g. foamed) plastics consisting wholly or partly of polyurethane to give end-prods. which do not contain toxic or additional by-prods. is effected by working-up the starting material to give a mixt. of low OH no. and then conventionally converting this to the end-prods. The process comprises (i) either (a) swelling the starting material (e.g. polyurethane scrap) in a suitable swelling agent and processing it to give a flowable gel particulate or (b) dissolving or dispersing the starting material in a suitable hydroxy polymer; (ii) adjusting the prod. to the desired OH no.; and (iii) working up the prod. (opt. via a prepolymer) to give a polyurethane which is opt. treated with a hardener system. Also claimed is appts. for effecting the process comprising a stirred reaction vessel fitted with a condenser, a protective gas device and opt. an ultrasonic mill, the novel feature being that such appts. is at least partly coated with a dehydratin catalyst of e.g. chicane, flat-plate or particulate configuration. USE/ADVANTAGE - Polyurethane scrap contg. other components such as other resins, pigments, lacquers, or fibres (e.g. scrap from car upholstery mfr.) can be worked up to give useful prods. which retain in large measure the chemical structure of the scrap. (10pp Dwg.No.0/0)