Solvent treatment of polyurethane leather to reduce

摘要

Treatment of porous plastic surfaces with a spray of solvent so as to reduce the average pore size and/or achieve certain discolouration effects, esp. if the material is a synthetic leather based on polyurethane resin. The solvent spray may incorporate a proportion of a varnish, and air heated to 40-100 deg.C. may be simultaneously passed over the surface. Esp. modification of polyurethane materials made porous by subsequent extraction of salt crystals of nominal particle size 5-25 microns or by spiking with needles and having a resulting pore size less than 100 micron, pref. 60-70% pore 1-10 micron as described BE. 688,286 by passing the material beneath a spray of dimethylformamide adjusted so that the droplets are 1-30 micron dia. when they contact the surface.