Radiation curable resin, composition thereof and precoated metal made therefrom

A precoated metal plate which comprises a base metal and a coat on at least one surface of the base metal formed by curing a radiation curable resin composition comprising a radiation curable resin which is a reaction product of:

• (1) a polyester polyol and/or a polycarbonate polyol,
• (2) a diisocyanate,
• (3) a polyfunctional (meth)acrylate containing a hydroxyl group therein which is selected from the group consisting of mono- or di-(meth)acrylates of triol compounds, hydroxyl group containing (meth)acrylates of tetrahydric or higher polyols and a mixture thereof, and optionally
• (4) a compound having at least two active hydrogen atoms in the molecule thereof selected from the group consisting of a polyol and a polyamine other than those used as component (1) or (3),
• said resin having at least two (meth)acryloyl groups at one terminal end of the molecular chain thereof, the molecular weight of said resin being 1,000 to 50,000, the concentration of urethane bond thereof being not more than 3,000 equivalent/10.sup.6 g and the concentration of (meth)acryloyl group thereof being 100 to 6,000 equivalent/10.sup.6 g;
• and
• a (meth)acrylate compound containing a hydroxyl group therein;
• the (meth)acryloyl group concentration in said composition being 400 to 9,000 equivalent/10.sup.6 g and the hydroxyl group concentration in said composition being 100 to 5,000 equivalent/10.sup.6 g.