Chromate-free wash primer

摘要

A carefully balanced formulation of a chromate-free wash-primer to be applied to the surface of predetermined metals as a surface conditioner to inhibit the spread of corrosion and to act as a tie-coat. The formulation comprises a mixture of polyvinyl butyl resin and an anti-corrosive pigment selected from salts of borates and salts of phosphates. It does not contain toxic components and therefore does not pose hazards to either operators or the environment, upon application or during subsequent thermal operations or maintenance procedures on metal substrates. The physical and application properties of the product according to the present invention are comparable to those of conventional wash-primers, which are based on zinc tetraoxy chromate, polyvinyl butyral solution in organic solvents and phosphoric acid used as the catalyst for the system.