Mitsubishi Kasei Corporation

Nihon Parkerizing Co., Ltd.

Haruo Iizuka

Yukio Tsuge

Takao Ogino

Takumi Honda

Noriaki Yoshitake

Hiroshi Okita

Kenshi Saeki

Akira Nishihara

Disclosed is an urethane acrylate oligomer to be obtained by reacting an isocyanate group-having urethane prepolymer and hydroxyl group-having acrylate and/or methacrylate, in which the urethane prepolymer is one having isocyanurate rings and the hydroxyl group-having acrylate and/or methacrylate comprises 4-hydroxybutyl acrylate and/or 4-hydroxybutyl methacrylate. The oligomer has a much lower viscosity of itself and a much higher ultraviolet-hardening speed, than the conventional urethane acrylate oligomers, and may be hardened to give a film having excellent physical properties of flexibility, heat resistance, weather resistance of hot-cold repetition cycles and scratch resistance.

Ultraviolet-hardening urethane acrylate oligomer

The present invention relates to a process for surface treatment for cathodic electrodeposit coating of a zinc-plated or zinc alloy-plated steel sheet comprising coating and drying a protective coating material on said steel sheet chromate-treated beforehand, to form a protective film before subjecting the sheet to the cathodic electrodeposit coating, which comprises coating a protective coating material having as a principal constituent of film-forming organic component a block isocyanate-containing prepolymer containing in one and the same molecule respectively at least one blocked isocyanate group, hydroxyl group, and tertiary amono group and containing 10-100 parts by weight of silica sol relative to 100 parts by weight of said prepolymer, in an amount of 0.3 g-4 g/m.sup.2, and then heat-drying the same.

Process for treating plated steel sheet

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Atugi, Japan

Haruo Iizuka