Process of coating a corrosion protect film on a steel substrate.

摘要

A corrosion protect film is coated on a steel substrate by the following process of the present invention. A primer paint includes as a pigment a zinc powder and as a vehicle resin an initial condensate obtained by hydrolysis of at least one alkoxysilane which is expressed by the following formula; Si (R1)x (OR2)4-x wherein R1 stands for a C1 to C5 alkyl group or alkenyl group, R2 stands for a C1 to C5 alkyl group, and x is 0 or 1, or a mixture of a colloidal silica and the initial condensate. The primer paint is coated on the steel substrate, and then dried to obtain a primer film with corrosion and heat resistance. A powder paint having a thermal shrinkage stress of 40 kg/cm<2> or less is coated on the primer film, and then baked thereto at a baking temperature to form a powder paint film thereon. Therefore, the corrosion protect film substantially consists of the primer film and the powder paint film. The process of the present invention is useful for providing the corrosion protect film with good adhesion strength to huge steel structures such as ships, plants, and bridges, etc., which are severely attacked for many years by the environments.