Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2001-02-27
2002-11-05
Green, Anthony J. (Department: 1755)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C106S014410, C106S014420, C106S014440, C148S243000, C427S328000, C427S387000, C427S409000, C427S419200, C428S472100
Reexamination Certificate
active
06475300
ABSTRACT:
FIELD OF THE INVENTION
The present, invention relates to a metal surface-treating agent for such steel substrates as cold-rolled steel, hot-rolled steel, stainless steel, electroplated zinc-coated steel, hot-dip zinc coated-steel, zinc-aluminum alloy-coated steel, zinc-iron alloy-coated steel, zinc-magnesium alloy-coated steel, zinc-aluminum-magnesium alloy-coated steel, aluminum-coated steel, aluminum-silicon alloy-coated steel, tin-coated steel, lead-tin alloy coated steel, and chromium-coated steel, a surface-treating method, a method of producing coated steel materials further having top coatings on the treated surfaces, and coated steel products as produced by the method.
PRIOR ART
As the metallic surface treating agent, a chromium-containing surface-treating agent such as a chromate system or a phosphate-chromate system has heretofore been used broadly and still in use today. However, in view of the recent trend toward more stringent regulatory control for environmental protection, it is likely that the use of such coating systems will be restricted for fear of the toxicity, particularly carcinogenicity, of chromium. Therefore, development of a metallic surface-treating agent not containing chromium and yet as effective as the chromating agent in imparting adhesion and corrosion resistance has been awaited.
As disclosed in Japanese Patent Hei-11-29724, the inventors of the present invention previously developed a nonchromate rust-preventive agent comprising a water-based resin and, as incorporated therein, a thiocarbonyl group containing compound, a phosphate ion, and water-dispersible silica. Regrettably, however, this system was found to be inadequate for the above application which requires stringent processability and adhesion, although it provides good corrosion resistance. Meanwhile, with regard to silane coupling agents, an acidic surface-treating agent containing two dissimilar silane coupling agents is disclosed in Japanese Kokai Publication Hei-8-73775. However, this system is quite deficient in corrosion resistance for use in applications where high corrosion resistance and good processability are required after metallic surface treatment as in the present invention.
Moreover, Japanese Kokai Publication Hei-10-60315 discloses a steel structure surface-treating agent containing a silane coupling agent having a certain functional group reactive with a water-based emulsion but the corrosion resistance required here is only that of a degree satisfying comparatively mild test requirements such as those of a wet test and as far as corrosion-resistance is concerned, the system is a far cry from the rust inhibitor meeting the highly critical corrosion resistance requirements as provided by the present invention. With the foregoing state of the art by way of background, there has been a standing demand for development of a metallic surface-treating agent expressing sufficient corrosion resistance and processing adhesion at thin coating thicknesses.
SUMMARY OF THE INVENTION
The present invention has for its object to provide a nonchromate metallic surface-treating agent which is suited for metallic substrates, particularly metal-coated steel materials, and despite the absence of chromium therein, is capable of imparting high processability and corrosion resistance in preparation for a coating or other procedure.
The nonchromate metallic surface-treating agent according to the present invention comprises, in each liter thereof,
(a) 0.01 to 100 g/l of a silane coupling agent and/or a hydrolytic condensation product thereof,
(b) 0.05 to 100 g/l of water-dispersible silica (as solids), and
(c) 0.01 to 50 g/l, in terms of Zr ion, of a zirconium compound and/or 0.01 to 50 g/l, in terms of Ti ion, of a titanium compound and/or
(d) 0.01 to 100 g/l of a thiocarbonyl-containing compound and/or
(e) 0.1 to 100 g/l of a water-soluble acrylic resin.
The nonchroinate metallic surface-treating agent according to the present invention may comprise 0.01 to 100 g/l of phosphate ion.
The method of treating a metallic surface according to the present invention comprises treating the surface of a steel material or a metal-coated steel material with the above metallic surface-treating agent and said method is most suited for the surface treatment of zinc-coated steel material.
The surface-treated steel material and surface-treated metal-coated steel material according to the invention can be obtained by the above-method with-said metallic surface-treating agent.
The method of producing a coated steel material according to the present invention comprises treating the surface of a metal-coated steel material with said metallic surface-treating agent and, then, applying a top coat thereon.
The coated steel material of the present invention is obtainable by the above method using said metallic surface-treating agent.
DETAILED DESCRIPTION OF THE INVENTION
As the silane compound as one of its essential components, the metallic surface-treating agent of the present invention comprises a silane coupling agent and/or a hydrolytic condensation product thereof. The hydrolytic condensation product of a silane coupling agent means an oligomer obtainable by hydrolytic polymerization of the silane coupling agent.
The silane coupling agent which can be used as above in the present invention is not particularly restricted but includes the following, among others: vinylmethoxysilane, vinyltrimethoxysilane, vinylethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysi.lane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl) -1-propanamine, N,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N-(&bgr;-aminoethyl)-&ggr;-aminopropylmethyldimethoxysilane, N (&bgr;-aminoethyl)-&ggr;-aminopropyltrimethoxysilane, &ggr;-aminopropyltrimethoxysilane, &ggr;-aminopropyltriethoxysilane, &ggr;-glycidoxypropyltrimethoxysilane, &ggr;-glycidoxy-propyltriethoxysilane, &ggr;-glycidoxypropylmethyl-dimethoxysilane, 2-(3,4-epQxycyclohexyl) ethyl-trimethoxysilane, &ggr;-methacryloxypropyltrimethoxysilane, &ggr;-methacryloxypropyltriethoxysilane, &ggr;-mercaptopropyltrimethoxysilane, &ggr;-mercaptopropyl-triethoxysilane and N-[2-(vinylbenzylaminolethyl]-3-aminopropyltrimethoxysilane.
The particularly preferred silane coupling agent includes vinylmethoxysilane, vinylethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyl-trimethoxysilane, 3-methacryloxypropyltriinethoxysilane, 3-mercaptopropyltriinethoxysilane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine and N,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine. These silane coupling agents can be used each alone or in a suitable combination.
In the present invention, said silane compound is formulated in a concentration of 0.01 to 100 g/l, preferably 0.05 to 25 g/l, in each liter of the metallic surface-treating agent. If the concentration of the silane compound is less than 0.01 g/l, the corrosion resistance-improving effect as well as the effect of improving adhesion to the nonchromate primer will be insufficient, while the use of the silane compound in excess of 100 g/l will result in saturation of the effect of addition and be uneconomical.
The metallic surface-treating agent of the present invention comprises water-dispersible silica. The water-dispersible silica which can be used is not particularly restricted but is preferably spherical silica, chainlike silica or aluminum-modified silica, which is lean in sodium and other impurities and weakly basic. The spherical silica includes colloidal silica such as “Snowtex N”, “Snowtex UP” (both manufactured by Nissan Chemical) and fumed silica such as “Aerosil” (Japan Aerosil); the chainlike silica includes silica gel such as “Snowtex PS” (Nissan Chemical); and the aluminum-modified silica includes “Adelite AT-20A” (Asahi Denka), all of which are commercially available.
The above water-dispersible silica is formulated in a concentration of 0.05 to 100 g/l, preferably 0.5
Kanai Hiroshi
Nomura Hiromasa
Sasaki Motohiro
Shimakura Toshiaki
Ueda Kouhei
Green Anthony J.
Nippon Paint Co. Ltd.
Sughrue & Mion, PLLC
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