SELF-CROSSLINKABLE ELECTROCOAT RESINS PREPARED BY ROOM TEMPERATURE REACTIONS OF EPOXY RESINS AND POLYAMINES CONTAINING PRIMARY AND TERTIARY AMINE GROUPS

摘要

A cathodically electrodepositable coating compsn. comprises an aq. dispersion of self-crosslinkable resin with amine and epoxide functionalities and is prepd. by reacting: (A) an epoxy resin having (a) on ave. 1-2 epoxide gps. and (b) an epoxide equiv. wt. of 400-4000 (pref. 450-2000); and (B) a polyamine contg. at least 1 primary amine gp. and at least 1 tertiary amine gp. and no other gps. capable of reacting with epoxide gps. The compsn. is prepd. in a reaction mixt. comprising: (i) a total of 70-25 wt.% of reactants (A) and (B) and (ii) 30-75 wt.% org. solvent in an amt. so as to provide 0.25-1.0 (0.5-1.0) primary amine gps. of (B) for each epoxide gp. of (A) at a temp. of 18-33 (21-27) deg.C in a period of time to react 20-50% of the epoxide gps. with active amine hydrogens to form an amine and epoxide functional, partially crosslinked resin having a wt. ave. mol. wt. (Mw) of 1300-12000 (pref. 2400-6500) and the amine gps. are neutralised with a water soluble acid in an amt. to neutralise at least 50% of them and the resin dispersed in water. The process for the prepn. of the coating compsn. is also claimed.