Use of epoxide as crosslinker or hardener for coating powder based on polyester with carboxyl groups, involves using special solid epoxide adducts with built-in organofluorine and/or organosilicon groups

摘要

The use of solid epoxide adducts with fluorine and organosilicon groups as crosslinkers or hardeners for coating powders based on polyesters with carboxyl groups, involves using adducts made by reacting solid mixed phases of triglycidyl mellitate and diglycidyl phthalate, isophthalate or terephthalate with solid cyclic fluorinated monocarboxylic acids and/or with half-esters from reactions of phthalic anhydride with monohydric fluoro-alcohols and/or hydroxybenzotrifluoride and/or organosilanols and/or silylated mono-alcohols. The use of solid epoxide adducts (C1) with 2-2.4 epoxide groups per average molecular weight and attached fluorine-containing and/or silicon-organic groups as crosslinkers or hardeners for the production of coating powders based on polyesters with carboxyl groups. Adducts (C1) are obtained by the addition reaction of a component (A3) comprising solid mixed phases of (i) triglycidyl trimellitate and (ii) diglycidyl phthalate and/or isophthalate and/or terephthalate, with an average content of 2.1-2.5 in the mixed phase, with a component (B) comprising (B1) cyclic fluorinated monocarboxylic acids with a melting point above 40 (preferably above 100) [deg] C and/or (B2) half-esters from the reaction of phthalic anhydride (PA) (or eutectic mixtures of dicarboxylic acid anhydrides containing PA) and fluorine-containing monohydric alcohols and/or hydroxyl-benzotrifluoride, and/or (B3) half-esters from the addition reaction of PA (or mixtures as above) and organosilanols with one or two hydroxyl groups and/or monohydric alcohols with at least one silyl group. The reaction is carried out at elevated temperature in bulk or in presence of organic solvent and/or catalysts for epoxy/carboxy addition reactions and/or polymerisation inhibitors and/or under inert gas, with the amounts of (A3) and (B) being such that the resulting adduct (C1) has 2-2.4 epoxide groups.