| 摘要 |
<p>Recycling of compact or porous (e.g. foamed) plastics consisting wholly or partly of polyurethane 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 dehydration catalyst of e.g. chicane, flat-plate or particulate configuration.</p> |
