Compositions comprising ionic resins and capped polyisocyanate mixtures containing a diphenyl-2,4'-diisocyanate and a diphenyl-4,4'-diisocyanate

摘要

Curable electrocoating compositions and the use of these compositions in a method of electrodeposition are disclosed. The electrocoating compositions comprise an aqueous dispersion of an active hydrogen-containing ionic resin and a capped polyisocyanate in which the polyisocyanate comprises a mixture of a diphenyl-2,4'-diisocyanate, a diphenyl-4,4'-diisocyanate and optionally polyphenyl polyisocyanate in which the diphenyl-2,4'-diisocyanate comprises at least 5 percent by weight of a polyisocyanate mixture. The capped polyisocyanate mixture results in a more stable aqueous dispersion than comparable dispersions prepared with capped polyisocyanates derived from the more common diphenyl-4,4'-diisocyanate and mixtures of diphenyl-4,4'-diisocyanate with polyphenyl polyisocyanate.