Method for producing precoated metals

A novel rationalized method is disclosed for producing precoated metal plates which are weather and corrosion resistant, and easily workable. The method of precoating metal plates comprises applying polymers in the form of a film to the surface of a metallic plate while heating and irradiating with electron beams. The composition is composed of more than 0.5 of olefinic unsaturated bonds per molecular weight of 1,000, in which the desired molecular weight of the polymer is more than 20,000. The temperature may preferably be 500C to 1200C. Polymers may be vinyl polymers having double bonds on their side chain, preferably unsaturated epoxyesters condensated by acrylic polymers, unsaturated carbonic acids and epoxy resins, or the same polymers modified by silicon. The energy level of the accelerated electron beams may be 0.1 to 3 MeV. In one of the embodiments, 240 g of eta-amyl alcohol, 30 g of methyl methacrylate, 51 g of azobisisobutyronitrile, and 3.1 g of n-dodecylmercaptane are mixed and polymerized at 1300C for 5 hrs while stirring. The degree of polymerization is 98%. A clear solid of acid value 160 is obtained after removing n-amyl alcohol under a lower pressure. 100g of this polymer, 40 mg of hydroquinone, 43 g of glycidyl methacrylate, 430 mg of triethyl benzyl ammonium chloride are mixed and agitated at 1200C for 1 hr to produce a reaction product of acid value 20 having a molecular weight of 45,000. The products to which have been added pigments are applied to a metallic plate and are subjected to an electron beam dose of 3 Mrad. (Iwakiri, K.)