| 摘要 |
A process for the removal of residual solvent from epoxide group containing acrylic copolymers for the production of powder paints is carried out by distillation followed by addition of polyisocyanates containing free or latent NCO groups. A process for the removal of residual solvent from epoxide group containing acrylic copolymers (I) produced by solution polymerisation for the production of powder paints is claimed. (I) is prepared in the presence of: (A) organic solvents with an alcoholic hydroxyl group; (B) ethyl acetate; and/or (C) diethyl malonate or, following the end of solution polymerisation of (I) in the presence of (D) organic solvents that are unreactive with polyisocyanates, (B) and/or (C) and/or (A) is added before or during distillation of the inert solvent. The boiling point of the inert solvent (D) is significantly lower than that of (A), (B) or (C), whereupon distillation of the solvent, optionally under vacuum yields a concentrated solution of (I) having a solids content of at least 95 wt.% and a residual solvent content of no more than 5 wt.%, that consists virtually only of (A), (B) and/or (C). (I) containing (A), (B) and/or (C) is reacted with polyisocyanates and/or their derivatives having free or latent, non-blocked NCO groups, optionally in the presence of catalysts for the -OH/NCO reaction, in the melt, optionally in an extruder such that the free or latent NCO groups are reversibly blocked by (A), (B) and/or (C) thereby removing them.
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