Coating compsn. for cathodic deposition - is prepd. from epoxy cpd., butadiene!-acrylonitrile! copolymer and partially blocked isocyanate cpd. and amino cpd.

摘要

The compsn. is prepared by reacting (a) 1 epoxy equiv. of an epoxy cpd. with (b) 0.2-0.7 carboxy equivs. of carboxyl contg. butadiene/acrylonitrile copolymer and, simultaneously or alternately, with (c) partially blocked isocyanate cpd. and amino cpd. The compsn. gives excellent adhesion of the coating film with the substrate combined with good corrosion resistance and solvent resistance. The cationic resin vehicle is prepd. by reacting the epoxy cpd., of epoxy equiv. 300-1000, with partially oxidised butadiene/acrylonitrile copolymer (pref. having 1.5-2.5 carboxyl gps. per molecule) at an elevated temp., and reacting the intermediate with partially blocked isocyanate (e.g. toluene diisocyanate of which one -CNO group is blocked with 2-ethylhexanol) and amino cpd. (e.g. dimethyl ethanolamine) at elevated temp. The resulting vehicle is then dispersed in water together with filler, pigment, etc.