Lacquer binder, esp. for electrocoating metals - from Mannich base and capped di-isocyanate or poly:isocyanate, reducing amine evolution on baking

• Main Authors: HARTMANN,HEINRICH,.DR, GULBINS,ERICH,.DR, ERDMANN,.KEMPTER,FRITZ
• Format: Patent
• Language: English; German
• Published: 21.06.1979
• Edition: 2
• Subjects: ADHESIVES; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COMPOSITIONS BASED THEREON; CORRECTING FLUIDS; DYES; FILLING PASTES; INKS; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; ORGANIC MACROMOLECULAR COMPOUNDS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; POLISHES; THEIR PREPARATION OR CHEMICAL WORKING-UP; USE OF MATERIALS THEREFOR; WOODSTAINS

The parent specification described a lacquer binder for the cathodic electro-dipping lacquering of electrically conducting surfaces comprising a protonated, heat-hardenable reaction prod. (A), free from epoxy gps., prodn. from (a) a Mannich base obtd. from (1) condensed poly-phenol, opt. contg. ether gps., (2) sec. amine (I) contg. 1 hydroxyalkyl gp., or a mixt. of (I) with another sec. amine, and (3) HCHO or a cpd. releasing HCHO, and (b) an epoxy resin. The binder contains 1-40 wt.%, w.r.t. A + B, of (B) a water-insol., nonionic resin, free from epoxy gps. and contg. urethane gps., obtd. by reaction of a partially blocked di- or poly-isocyanate with a polyamidepolyamine with mol.wt. 400-1000 or a reaction prod. of a polyepoxide and not 1 low-mol. cpd. contg. SH and/or OH gps. In this Patent of addn. resin (B) is a capped di- or polyisocyante. Current consumption during electro-lacquering is lower, Fresh coatings have less tendency to redispersion. The binder can be applied at a constant pH of 6.5-10 (7-9). Release of amine during baking is reduced Hard coatings are obtd., resistant to scratching, solvents and salt spray.