Surface-treated steel sheet with resin-based chemical treatment coating and process for its production
AssigneeNippon Steel Corporation
InventorsTadashi Sakon, Ikuo Jitsuhara, Kenichiro Tadokoro, Maki Sekoguchi, Hiromasa Shoji, Makoto Yamazaki
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Abstract
A surface-treated steel sheet with a resin-based chemical treatment coating on the steel sheet surface, having poorly soluble chromate colloid particles finely dispersed in a matrix resin such that the mean particle size of the dispersed particles is under 1 .mu.m.
Claims19
A surface-treated steel sheet comprising a steel sheet and a resin-based chemical treatment coating, wherein said resin-based chemical treatment coating comprises a matrix resin and colloid particles of at least one chromate selected from the group consisting of ZnCrO.sub.4, SrCrO.sub.4, BaCrO.sub.4, CuCrO.sub.4, FeCrO.sub.4, Ag.sub.2 CrO.sub.4, and SnCrO.sub.4 dispersed in said matrix resin in a weight ratio range of 50/1 to 1/1, and wherein said colloid particles are less than 1 .mu.m in terms of the mean particle size of the particles dispersed in said matrix resin.
A process for producing a surface-treated steel sheet which comprises the steps of
- adding a metal ion-containing aqueous solution to an aqueous chromic acid solution, said metal ion being at least one selected from the group consisting of Zn, Sr, Ba, Cu, Fe, Ag and Sn,
- adjusting the pH of said aqueous solution to 5-12, a chromate colloid being formed during said addition of the metal ion or during said adjustment of the pH, with said chromate being at least one selected from the group consisting of ZnCrO.sub.4, SrCrO.sub.4, BaCrO.sub.4, CuCrO.sub.4, FeCrO.sub.4, AgCrO.sub.4, and SnCrO.sub.4, with particle size of said chromate colloid being less than 1 .mu.m in terms of mean particle size,
- mixing a dispersion or solution of a resin with said aqueous solution to prepare a resin-based chemical treatment solution, and
- coating a steel sheet surface with said resin-based chemical treatment solution and drying it to form a resin-based chemical treatment coating on the steel sheet surface.
A process for producing a surface-treated steel sheet which comprises the steps of
- preparing an aqueous chromic acid solution adjusted to a pH of 5-12,
- adding a metal ion-containing aqueous solution to said aqueous chromic acid solution to form a chromate colloid, said metal ion being at least one selected from the group consisting of Zn, Sr, Ba, Cu, Fe, Ag and Sn, with said chromate being at least one selected from the group consisting of ZnCrO.sub.4, SrCrO.sub.4, BaCrO.sub.4, CuCrO.sub.4, FeCrO.sub.4, Ag.sub.2 CrO.sub.4, and SnCrO.sub.4, with particle size of said chromate colloid being less than 1 .mu.m in terms of mean particle size,
- mixing a dispersion or solution of a resin in said aqueous solution to prepare a resin-based chemical treatment solution, and
- coating a steel sheet surface with said resin-based chemical treatment solution and drying it to form a resin-based chemical treatment coating on the steel sheet surface.
A process for producing a surface-treated steel sheet which comprises the steps of
- preparing an aqueous emulsion resin or latex of a polymer obtained from one or more hydrophobic vinyl-based compound monomers and/or one or more olefin-based compound monomers,
- adding an aqueous chromic acid solution adjusted to pH 5-12 and an aqueous solution containing a metal ion to said emulsion or latex to form a chromate colloid, said metal ion being at least one selected from the group consisting of Zn, Sr, Ba, Cu, Fe, Ag and Sn, with said chromate being at least one selected from the group consisting of ZnCrO.sub.4, SrCrO.sub.4, BaCrO.sub.4, CuCrO.sub.4, FeCrO.sub.4, Ag.sub.2 CrO.sub.4, and SnCrO.sub.4, with particle size of said chromate colloid being less than 1 .mu.m in terms of mean particle size,
- adding to said colloid-containing emulsion or latex one or more from among emulsion resins or latexes of
- i) either or both a block copolymer or telechelic resin which has a skeleton or functional group at one end with affinity for the chromate colloid and a skeleton or functional group at another end with affinity for metals and of which the remainder is a hydrophobic molecular skeleton,
- ii) a copolymer of a polymer obtained from one or more monomers selected from among hydrophilic vinyl-based carboxylic acids, vinyl-based amines, vinyl-based phosphates and vinyl-based alcohols and a polymer obtained form one or more hydrophobic vinyl-based compound monomers and/or olefin-based compound monomers, or a polymer which is a polymer obtained from one or more hydrophobic vinyl-based compound monomers and/or olefin-based compound monomers and has a functional group at the end with affinity for metal surfaces, or
- iii) a core/shell resin whose core phase is a polymer obtained for one or more hydrophobic vinyl-based compound monomers and/or olefin-based compound monomers, and whose shell phase is one or more polymers with affinity for the chromate colloid and for metal surfaces,
- to prepare a resin-based chemical treatment solution, and
- coating a steel sheet surface with said resin-based chemical treatment solution and drying it to form a resin-based chemical treatment coating on the steel sheet surface.
Dependencies are inferred from the claim text.