Method for the formation of paint films and the paint films

Abstract

A method for the formation of a paint film in which an aluminum or aluminum alloy part is subjected to an anodic oxidation treatment and an anodic oxide film is formed on the surface of the aluminum or aluminum alloy part, an anti-rust primer is coated on said anodic oxide film and an anti-rust primer paint film is formed and, as required, a top-coat paint is coated on said anti-rust primer paint film and a top-coat paint film is formed in which said anti-rust primer includes a base resin comprising hydroxyl group containing epoxy resin and a hardening agent, selected from among melamine resin and polyisocyanate, and barium sulfate, and the proportion of said barium sulfate included is a proportion within the range from 20 to 70 parts by mass per 100 parts by mass in total of the solid fractions of the base resin and the hardening agent.

1 . A method for the formation of a paint film, comprising
 subjecting a part selected from the group consisting of an aluminum part and an aluminum alloy part, is subjected to an anodic oxidation treatment so as to form an anodic oxide film on the surface of the part,   coating an anti-rust primer on said anodic oxide film so as to form an anti-rust primer paint film,   and optionally coating a top-coat paint on said anti-rust primer paint film so as to form a top-coat paint film,   wherein the anti-rust primer comprises   a base resin comprising a hydroxyl group containing epoxy resin,   a hardening agent selected from the group consisting of melamine resin and polyisocyanate, and   barium sulfate, wherein the proportion of said barium sulfate included is a proportion within the range from 20 to 70 parts by mass per 100 parts by mass in total of the solid fractions of the base resin and the hardening agent.   
     
     
         2 . The method of  claim 1  further comprising carrying out the aforementioned anodic oxidation treatment in a dilute sulfuric acid bath. 
     
     
         3 . The method of  claim 2  further comprising subjecting the anodic oxide film on which the aforementioned anti-rust primer is coated to a hole-sealing treatment. 
     
     
         4 . A paint film obtained by the method for the formation of a paint film of  claim 1 .