Composition for application of vitreous enamel coating onto sheet metal, comprises frit, solvent and thermosetting resin containing at least poly-hydroxy- polyester and-or poly-hydroxy polyacrylate, and crosslinking agent

摘要

Composition for application of vitreous enamel coating onto sheet metal, comprises frit, solvent and thermosetting resin containing at least poly-hydroxy- polyester and-or poly-hydroxy polyacrylate, and crosslinking agent. The composition comprises thermosetting resin, solvent for this resin and at least 50 wt.% of vitreous enamel frit. Thermosetting resin comprises a) one or more poly-hydroxy polyesters and/or one or more poly-hydroxy polyacrylates in solution and/or emulsion, having OH (hydroxy) index (No.) 3-100 mg KOH/g, with average molecular wt. of dissolved polymers fraction below 100000 g/mol; b) at least one crosslinking agent causing reaction of transesterification or polyaddition between hydroxy groups of above polymers; c) a catalyst, in sufficient quantity to catalyze the reaction between hydroxy groups of polymers and at least one crosslinking agent. The composition preferably also contains lubrication additive. Independent claims are also included for 1) process of producing sheet metal coated with vitrifiable enamel coating, comprising preparation of composition as claimed, application of composition onto sheet metal to be coated, and curing coated sheet metal under conditions required to cause crosslinking of resin, with additional stage of vitrification of coating; and 2) process of producing enamelled sheet metal article, comprising preparation of composition as claimed, applying it onto sheet metal, curing under resin crosslinking conditions, forming an article from sheet metal coated with crosslinked composition, and curing formed coated article under conditions ensuring complete pyrolysis of crosslinked resin as well as vitrification of frit.