Process for the recovery of overspray from water-coatings during spraycoating in spray booths

摘要

A process for the recovery of oversprays from water-coatings during spray coating in spray booths, in which the overspray is collected in an aqueous washing liquid which is continuously returned in a circulation (A) to the spray booth, a part of the washing liquid which contains the overspray being fed from the circulation (A) to an ultrafiltration circulation (B), and permeate being withdrawn in the ultrafiltration circulation (B) and returned to supplement the washing liquid into the circulation (A), in which the washing liquid used is the water-coating, which is used in the spray booth for spray coating, in a form diluted with water, the liquid circulating in the ultrafiltration circulation (B) is the water-coating, which is used in the spray booth for spray coating, if required, in a form diluted with water, and the process is carried out continuously, the washing liquid having in the circulation (A) an approximately constant solids content which is in the range from 4 - 20 % by weight, and the liquid circulating in the ultrafiltration circulation (B), by withdrawal of permeate, being kept at an approximately constant solids content in the range from 15 % by weight to the solids content which results from the spraying viscosity of the water-coating and is higher than the solids content in the circulation (A), and a part of the liquid circulating in the ultrafiltration circulation (B) being used as a water-coating for spray coating in the spraying booth or for the treatment thereof.