Process for recovering binder components from lacquer sludge

Abstract

The present invention relates to a process for recovering and recycling the organic binder components accumulating as overspray during the spraying of a solvent-containing, two-component polyurethane lacquer or a solvent-containing, moisture-curing, one-component polyurethane lacquer by i) washing the overspray out of the exhaust air of a coating plant with the aid of an aqueous medium which a) contains in dissolved or dispersed form compounds that exhibit greater reactivity towards isocyanate groups than either water or the isocyanate-reactive groups present in two-component polyurethane lacquers, and b) may contain emulsifiers, ii) isolating the chemically modified overspray formed in step (i) in the form of lacquer sludge by treatment with coagulating agents, which may be present in the aqueous medium, iii) mixing the lacquer sludge, containing fully reacted lacquer constituents, coagulating agents and water, optionally after a portion of the water is removed, with an organic solvent and iv) separating the organic phase accumulating in step iii) from the aqueous phase and insoluble-constituents which may be present and recovering the solution of modified organic binder components dissolved in the organic phase.

Dependencies are inferred from the claim text.