PROBLEM TO BE SOLVED: To provide a composite board superior in contamination resistance and weather resistance and high in surface hardness by providing a board composed of a synthetic resin board on the rear face of an aluminum enameled board with an enamel layer formed on the surface of an aluminum board. ;SOLUTION: An aluminum board 2 is stuck through an adhesive layer 4 on a synthetic resin board 1, and an enamel layer 3 is formed on the surface of the aluminum board 2. In order to form the enamel layer 3 on the surface of the aluminum board 2, glaze containing as a main component silicon dioxide is applied and incinerated to form the enamel layer 3. When Mg contains in the aluminum board 2, oxide of Mg is formed between the enamel layer 3 and the aluminum board 2, and since a problem in which adhesion of the enamel layer 3 and the aluminum board 2 is lowered exits, material of the aluminum board 2 is preferably a pure aluminum board. Thus, even thought it is moistened, the board is not rusted and corroded, since the enamel layer is formed on the surface, surface hardness is high, contamination resistance is superior, and dirt on the surface can be simply removed.;COPYRIGHT: (C)1998,JPO
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