Aqueous epoxy resin compositions and metal substrates coated therewith
First Claim
1. An aqueous composition comprising:
- (A) an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersable or emulsifiable epoxy resin wherein the epoxy resins are the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid,(B) chromium trioxide in an amount to provide at least about 12 parts by weight of hexavalent chromium metal per 100 parts by weight of solid resin (A), and(C) at least about 25% by weight of water, said composition further characterized as being substantially free of strontium chromate.
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Abstract
This invention relates to aqueous epoxy resin-containing compositions and to such compositions which are particularly useful for depositing coatings on metallic substrates in order to protect substrates against corrosion. The aqueous compositions generally comprise (A) an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersible or emulsifiable epoxy resin, (B) chromium trioxide, and (C) water, said composition further characterized as being substantially free of strontium chromate. The aqueous compositions may also contain other ingredients including zinc and/or ferro alloys.
These aqueous compositions are useful as pretreatment coatings on metal surfaces, and in particular, on steel and on galvanized and aluminized metal substrates. This pretreatment coating can then be coated with weldable or non-weldable primer coatings followed by the application of decorative topcoats such as appliance topcoats or automotive topcoats. The invention also relates to metal substrates which have been coated with the pretreatment coating and, optionally, the weldable or non-weldable primer coatings.
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Citations
35 Claims
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1. An aqueous composition comprising:
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(A) an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersable or emulsifiable epoxy resin wherein the epoxy resins are the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid, (B) chromium trioxide in an amount to provide at least about 12 parts by weight of hexavalent chromium metal per 100 parts by weight of solid resin (A), and (C) at least about 25% by weight of water, said composition further characterized as being substantially free of strontium chromate. - View Dependent Claims (2, 3, 4, 5, 28, 30, 31)
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6. An aqueous composition comprising:
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(A) from about 2 to about 25% by weight of an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersible or emulsifiable epoxy resin wherein the epoxy resins are the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid, (B) chromium trioxide in an amount to provide at least about 12 parts by weight of hexavalent chromium metal per 100 parts by weight of solid resin (A), and (C) from about 25 to about 97% by weight of water, said composition further characterized as being substantially free of strontium chromate. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 29)
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18. An aqueous composition comprising:
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(A) an organic resin component consisting essentially of at least one water-dispersible or emulsifiable epoxy resin, or a mixture of resins containing more than 50% by weight of at least one water-dispersible or emulsifiable epoxy resin, wherein the epoxy resins are the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid, (B) chromium trioxide, (C) at least about 25% by weight of water, and (D) zinc powder or a ferro alloy powder or mixtures thereof. - View Dependent Claims (19, 20, 21, 22, 32, 33)
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23. A water-borne liquid coating composition comprising:
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(A) from about 2 to about 25% by weight of at least one water-dispersible or emulsifiable epoxy resin or a mixture of resins containing more than 50% by weight of at least one water-dispersible or emulsifiable epoxy resin, wherein the epoxy resins are characterized as having an epoxide equivalent weight of from about 1000 to about 3000 and wherein the epoxy resins ar the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid, (B) from about 0.5 to about 5% by weight of chromium trioxide, (C) from about 25 to about 90% by weight of water, (D) from about 5 to about 60% by weight of zinc powder, and (E) from about 0.5 to about 3% by weight of phosphoric acid or butyl phosphoric acid. - View Dependent Claims (24, 25, 26, 34, 35)
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27. An improved corrosion-resistant water-borne liquid pretreating basecoat composition for metallic substrates, said composition comprising:
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space="preserve" listing-type="tabular">______________________________________Constituents Concentration (wt. %)______________________________________Water-dispersible epoxy resin 2.1-18.4Chromium trioxide powder 0.8-4.6Phosphoric acid 0.8-2.7Zinc powder 6.2-51.5Water 29.2-88.0______________________________________wherein the epoxy resin is the product of the condensation reaction of an epihalohydrin and an aliphatic or aromatic polyhydroxy compound, or a polycarboxylic acid, said composition having a bake temperature of about 390°
F. to 450°
F. to provide a flexible crack-resistant coating on steel and on galvanized and aluminized metal substrates.
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Specification