Environment-friendly spray painting - where spray compsn. contains ultrafiltration throughput setting component and recirculated water conductivity is monitored

摘要

Environment-friendly spray painting using a water-thinnable two-component lacquer takes place in a spraying operation using a compartment with a water-spraying rear wall for collection and washing out of overspray in the waste water, which is sepd. into permeate and lacquer-contg. residue by ultrafiltration. The permeate is recirculated to the paint spraying stage, the lacquer-contg. residue is conc. in lacquer by water extn. such that the lacquer content is the same as for the paint spraying stage and it is returned to the fresh spray compsn. which contains a component for deceleration of polymerisation of the two-component lacquer and one for hindering coalescence of the lacquer. To the waste water a component is added for setting throughout on ultrafiltration, and the conductivity of the water recirculated to the spraying stage is monitored and held below a boundary value. ADVANTAGE - The process is environment-friendly with recirculation of the water and lacquer.