Junichi Fujikawa

Electron beam curing coatings and process for high-grade precoated steel sheet

Abstract The developments on electron beam curable coatings for high-grade precoated steel sheet have been carried out by the co-research with Nippon Steel Corp. and Toray Industries Inc. As the results of the co-research, the coatings which satisfy the demanded properties for high-grade precoated steel sheet was obtained. The coatings are curable in low electron beam irradiation (2∼3Mrad), and the cured coating film has excellent post-formability with good appearance, hardness, gloss, chemical resistance, stain resistance, boiling water resistance, corrosion resistance and heat resistance. The main formulations of the coatings consist of saturated acrylic copolymer, cross-linking agents (polyfunctional vinyl monomers), pigments and diluents (no reactive). After the coatings are applied on electrogalvanized and chromated steel sheet, the diluents are flashed off, and then the coating films are irradiated by low energy electron beam in nitrogen atmosphere. Irradiating conditions such as the voltage of electron beam, irradiating dose and oxygen concentrations in nitrogen atmosphere was examined with relation to the film properties, and optimum conditions were found. The precoated steel sheets obtained are excellent in post-formability, therefore vast uses are expected in the fields such as home electrical appliances, daily necessities, kitchenwares, office equipments and constructions.