METHOD FOR RE-ENRICHMENT OF EXCESSIVE SPRAY OF ONE COMPONENTTYPE COATING COMPOSITION

摘要

PURPOSE: To provide a method in such a manner that the overspray from a coating material composition dilutable with water is reprocessed and the substan tially original composition and thus the fresh coating material composition having the original quality may be formed. CONSTITUTION: This invention relates to a multi-stage membrane filtration process for reconcentrating a mixture composed of spray chamber water/ overspray formed by wet flushing of the overspray of the one-component, aqueous coating material composition containing low molecular weight components having a weight average molecular weight of <=2000 and at least 5% by weight, based on the total weight of the organic components having a weight average molecular weight of 2000. (a) A first retenate and a first permeant are obtained by preconcentrating the mixture composed of the spray chamber water/overspray in an ultrafiltration device 3; (b) a second permeant and a second retenate are obtained by treating the first permeant and a third permeant obtained in the following stage (c) in a reverse osmosis device 6, and (c) the third permeant and a third retenate are obtained by treating the first and second retenates in a nanofiltration device 9.