Method for environmentally friendly paint spray painting using an air-drying lacquer which is soluble, emulsifiable or dispersible in water

摘要

In painting in a paint-spray booth (1) with a water-sprinkled rear wall (2), the booth effluent is divided by ultrafiltration (13) into permeate and paint-containing residue. The permeate is recycled. Fresh spray composition is fed in. The paint is preferably an alkyd resin, an acrylic resin, a polyvinyl acetate resin, a silicone resin, a copolymer thereof, a mixed polymer thereof or a mixture thereof. The spray composition contains one component for preventing coalescence, preferably one or more aliphatic amines having an average molecular weight from 75 to 133 or mixtures or derivatives thereof, and a component for delaying the drying. If the paint used is emulsifiable or dispersible in water, the spray composition and/or the booth effluent preferably contains a component for stabilising the emulsion or dispersion. The booth effluent contains a component for adjusting the throughput, preferably a derivative of glycol or of a higher alcohol. The spray composition and/or the booth effluent can contain a biocidal component. The conductivity of the fresh water is maintained below a limit of preferably 10-4 OMEGA -1 cm-1, preferably by reverse osmosis. The paint-containing residue from the booth effluent is concentrated by removal of water until its paint content is approximately equal to that of the fresh spray composition. The residue thus concentrated is re-used. The concentrating and the re-use can be carried out continuously or discontinuously and, in the latter case, the concentrated residue is put into temporary storage. IMAGE