Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
1999-12-21
2001-11-06
Boykin, Terressa M. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polycarbonate
Reexamination Certificate
active
06312812
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to corrosion-resistant coated metal substrates and, more particularly, to ferrous and non-ferrous metal substrates having environmentally friendly chrome-free and nickel-free coatings thereon which inhibit corrosion of the metal substrate.
BACKGROUND OF THE INVENTION
Pretreating metal substrates with a phosphate conversion coating and rinsing with a chrome-containing sealer is well known for promoting corrosion resistance and improving the adhesion of subsequently applied decorative and protective coatings. Cationic electrodeposition compositions are typically applied over phosphated steel substrates to further improve corrosion resistance. While the combination of phosphate conversion coating and electrodeposited coating provides superior corrosion resistance, heavy metals typically used in such coatings can provide environmental disposal concerns. For example, phosphate conversion coating compositions typically contain heavy metals such as nickel and post-rinses contain chrome, while cationic electrodeposition compositions typically are formulated with lead as a pigment or soluble lead salt. Also, conventional phosphating processes can require eleven to twenty-five stages that occupy a large amount of physical space in a plant and require significant capital investment. Another drawback of conventional phosphating processes is difficulty in coating mixed-metal objects including aluminum.
Nickel-free phosphate coating compositions and chrome-free rinsing compositions having comparable corrosion resistance to nickel- and chrome-containing compositions are highly desirable. Rinsing compositions utilizing metal ions other than chromium are disclosed, for example, in U.S. Pat. Nos. 3,966,502 and 4,132,572. U.S. Pat. No. 3,966,502 discloses treatment of phosphated metals with zirconium-containing rinse solutions. U.S. Pat. Nos. 3,912,548, 5,209,788, and 5,653,823 disclose other rinse compositions containing combinations of Group IVB metal ions with polymeric materials that have been used over phosphated substrates. However, many post-rinse compositions are suitable for use over a limited number of substrates or over substrates that must be phosphated first.
It would be desirable to provide a simplified pretreatment process free of heavy metals for coating metal substrates, including mixed metal substrates such as are commonly found on today's automobile bodies. Such a pretreatment process, when combined with a lead-free electrodeposition process, would provide an environmentally friendly alternative for providing corrosion resistance to metal substrates.
SUMMARY OF THE INVENTION
The present invention provides a coated metal substrate comprising: (a) a metal substrate; (b) a first pretreatment composition deposited upon at least a portion of the substrate, the first pretreatment composition comprising a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof; and (c) a second pretreatment composition comprising a reaction product of at least one epoxy-functional material or derivative thereof and at least one material selected from the group consisting of phosphorus-containing materials, amine-containing materials, sulfur-containing materials and mixtures thereof deposited upon at least a portion of the first pretreatment composition.
In another aspect of the present invention, a weldable, coated metal substrate is provided which comprises (a) a metal substrate; (b) a first pretreatment composition comprising a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof deposited upon at least a portion of the substrate; (c) a second pretreatment composition comprising a reaction product of at least one epoxy functional material or derivative thereof and at least one material selected from the group consisting of phosphorus-containing materials, amine-containing materials, sulfur-containing materials and mixtures thereof deposited upon at least a portion of the first pretreatment composition; and (d) a weldable composition comprising an electroconductive pigment and a binder deposited upon at least a portion of the second pretreatment composition.
In another aspect of the present invention, a coated metal substrate is provided which comprises: (a) a metal substrate; (b) a first pretreatment composition comprising a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof deposited upon at least a portion of the substrate; and (c) a second pretreatment composition comprising an ester of a phosphorus-containing material deposited upon at least a portion of the first pretreatment composition.
In another aspect of the present invention, a method for preparing a coated metal substrate is provided which comprises the steps of: (a) treating a surface of a metal substrate with a first pretreatment composition comprising a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof; and (b) applying a second pretreatment composition comprising a reaction product of at least one epoxy functional material or derivative thereof and at least one material selected from the group consisting of phosphorus-containing materials, amine-containing materials, sulfur-containing materials and mixtures thereof over at least a portion of the first pretreatment composition to form a substrate having a pretreated surface.
In another aspect of the present invention, a method for inhibiting corrosion of a metal substrate is provided which comprises: (a) treating a surface of a metal substrate with a first pretreatment composition comprising a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof; (b) applying a second pretreatment composition comprising a reaction product of at least one epoxy functional material or derivative thereof and at least one material selected from the group consisting of phosphorus-containing materials, amine-containing materials, sulfur-containing materials and mixtures thereof over at least a portion of the first pretreatment composition to form a substrate having a pretreated surface; and (c) applying a weldable coating to the pretreated surface to form a corrosion-resistant coated metal substrate, the weldable coating comprising an electroconductive pigment and a binder.
In another aspect of the present invention, a coated metal substrate is provide which comprises: (a) a metal substrate; and (b) a pretreatment composition deposited upon at least a portion of the substrate, the pretreatment composition comprising (1) a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group IVB elements, lanthanide series elements and mixtures thereof; and (2) a reaction product of at least one epoxy-functional material or derivative thereof and at least one material selected from the group consisting of phosphorus-containing materials, amine-containing materials, sulfur-containing materials and mixtures thereof deposited upon at least a portion of the first pretreatment composition.
In another aspect of the present invention, a method for preparing a coated metal substrate is provided which comprises the step of treating a surface of a metal substrate with a pretreatment composition comprising (1) a transition element-containing material which comprises a transition element selected from the group consisting of Group IIIB elements, Group
Gray Ralph C.
Hauser Brian T.
Nugent, Jr. Richard M.
White Michael L.
Altman Deborah M.
Boykin Terressa M.
PPG Industries Ohio Inc.
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