Compositions: coating or plastic – Coating or plastic compositions – Corrosion inhibiting coating composition
Patent
1987-09-30
1989-06-20
Willis, Prince E.
Compositions: coating or plastic
Coating or plastic compositions
Corrosion inhibiting coating composition
106404, 106425, 106439, 106441, 106453, 106456, 106479, C09D 508, C04B 1434, C09C 100
Patent
active
048406686
DESCRIPTION:
BRIEF SUMMARY
In the production of varnishes and paints for coating non-ferrous metal substrates, but also, particularly, structures and vehicles made of various metals such as steel, galvanized steel and aluminum, zinc chromate and strontium chromate have thus far been depended upon as the only two compounds providing the required adhesion of coatings, particlarly on aluminum.
Research efforts aimed at substituting zinc and strontium chromate pigments, rated as carcinogenic substances, by zinc phosphate pigments or modified zinc phosphate pigments for the above-defined applications have not been successful. First of all, the very good adhesion properties of zinc chromate and strontium chromate on various aluminum alloys under weathering test conditions could not be matched thus far by using phosphate pigments.
It is an object of the present invention to provide environmentally harmless corrosion-inhibiting pigments, the pigments in particular being less objectionable from the standpoint of industrial medicine, and capable of substituting zinc chromate and strontium chromate, especially in priming coats for various metal substrates.
It has been determined that modified basic phosphate pigments exhibiting optimum effectiveness when applied on steel substrates can be significantly improved to be applicable with good results also on light-metal substrates by combining the pigments with very small amounts of soluble dichromates or chromates of alkali metals, ammonium dichromate or chromate, or chromic acid.
The small amounts of soluble chromates or chromic acid added to primers as pigments markedly improve the adhesion and rust protection properties of the priming coats.
It is even possible to keep the percentage of soluble dichromates or chromic acid so low that the concentration range of the material as per its specification will not be changed.
The invention provides, accordingly, corrosion-inhibiting pigments containing metallic oxides, phosphates and/or molybdates, preferably basic pigments containing metallic phosphates and molybdates with the metals being zinc, aluminum, iron, barium, strontium, calcium, magnesium and titanium, singly or in combination, which, beside metallic oxide, metallic phosphate and/or metallic molybdate also contain 0.03-2% by weight, preferably 0.2-0.6% of soluble sodium dichromate, or equivalent amounts of potassium or ammonium dichromates or equivalent amounts of respective chromate or chromic acid in relation to the total weight of the pigment.
Efforts were made to develop pigments containing certain amounts of soluble chromates by combining the phosphate pigments with zinc chromate or strontium chromate. However, the resulting pigments only matched the quality of the pigments of this invention when the percentage of strontium chromate and zinc chromate was very high, the amount of chromates in those pigments thus being higher by several orders of magnitude than in the pigments of the present invention.
Attempts have been made for a long time to combine phosphates or oxides with chromate. According to German Patent (DE) 667 135, a pigment can be obtained by saturation of an adsorptive powdery material with aqueous solutions of chromic acid or chromates with subsequent drying and grinding. This method, however, requires ca. 25% to 53% of chromic acid or chromates in relation to the adsorptive powdery material or 20% to 35% in relation to the final pigment. Such an amount is intolerable from the standpoint of industrial medicine.
According to DD-PS 1082, lead chromate is combined with a carrier wherein the resulting amount of insoluble lead chromate (no soluble chromate radical) is from 5% to 11% [percent] by weight. It is also known to use chromates in the form of permanently adsorbed matter or in an insoluble form. However, it is new and unexpected to find out that the rust-protection properties can be significantly improved over the prior art by using very low amounts of soluble chromium compounds, since it was determined that at higher percentages (over 2%, especially over 5%) not only d
REFERENCES:
patent: 2172505 (1939-09-01), Gardner
patent: 3248251 (1966-04-01), Allen
patent: 3443977 (1969-05-01), Bennetch
patent: 3656975 (1972-04-01), Phelps, Jr. et al.
patent: 3874883 (1975-05-01), Robitaille et al.
patent: 3963472 (1976-06-01), Young
patent: 3969127 (1976-08-01), Robitaille et al.
patent: 4017315 (1977-05-01), Vukasovich et al.
Adrian Gerhard
Gawol Manfred
Dr. Hans Heubach GmbH & Co. KG
Kirschner Helene
Willis Prince E.
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