Powder coating compsn. for metal pipes and containers - comprises epoxy cpd. and imidazoline blocked poly:isocyanate hardener

摘要

Metal pipes and containers are coated by heating the pipe or container, after any necessary cleaning, to 200-300 deg. C, coating electrostatically by vortex sintering or pneumatically with a powder paint, hardening using the heat capacity of the work piece without further heating for 10-60 pref. 30-50 sec. and quenching. The powder paint comprises a 1,2-epoxy cpd. (I) with a min. melting temp. of greater than 60 deg. C, 2-15 pref. 6-12wt.% (w.r.t. (I)), opt. chain extended polyisocyanate hardener blocked with an imidazoline blocking agent of formula (II) (where R is H, (cyclo)alkyl, aralkyl, aryl or 2 geminal or neighbouring R are cycloalkyl). The coatings are impact, abrasion and corrosion resistant and can be used esp. on large dia. pipes used for petrochemicals.