US 5,077,332 AGranted

Chromate-free wash primer

AssigneeHer Majesty the Queen in right of Canada, as represented by the Minister of National Defence

InventorsPaul Blattler, Marek Szandorowski

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Abstract

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.

Claims9

Dependent claims

A wash-primer base paint composition, to be mixed with a catalyst composition to produce a wash-primer which may be applied to the surface of predetermined metals, the base paint composition comprising the following ingredients in the following relative concentrations by weight:

(a) about 40 to 54%, per total non-volatile, polyvinyl butyral resin, having 80 to 85% by weight butyral content, 10 to 20% hydroxyl content and 0 to 2% residual acetate content;
(b) about 20 to 30%, per total non-volatile, anticorrosive pigments of a mixture of salts of borates and salts of phosphates, the weight ratio of borate salt to phosphate salt being between about 3:1 to 5:1, and, in addition to components (a) and (b),
(c) the balance of the ingredients being at least one of:
(i) a silane coupling agent
(ii) hydrophobic pyrogenic silica
(iii) inert extenders
(iv) inert coloring pigments excluding the anticorrosive pigments of (b)
(v) pigment wetting agents
(vi) solvent blend.

6 more elements

Dependencies are inferred from the claim text.