[0001]The present invention relates to a galvanized steel sheet and a manufacturing method thereof.
　The present application, on December 28, 2015, claiming priority based on Japanese Patent Application No. 2015-256743, filed in Japan, the contents of which are incorporated here.
Background technique
[0002]Conventionally, as a rust-proofing of the galvanized steel sheet, chromate treatment has been widely used. However, it is seen as a problem hexavalent chromium is harmful to the human body. Particularly in recent years, the movement to regulate the hexavalent chromium from the viewpoint of environmental protection and are accelerated, anticorrosive treatment of various chromate-free have been developed and put to practical use.
[0003]
　Further, in order to improve the corrosion resistance of galvanized steel sheet, has been practically galvanized steel sheet galvanized layer contains Mg. Galvanized steel sheet containing Mg are poor blackening resistance, that is, when prolonged exposure to the environment of high temperature and high humidity, it is known that the commercial value markedly tends to decrease the plating surface is blackened there.
[0004]
　As a technique for improving the corrosion resistance and blackening resistance of the galvanized steel sheet containing Mg, for example, a chromate-free coating such as the Patent Document 1 is known to form the galvanized layer. Chromate-free coating of Patent Document 1, basic zirconium compound, vanadyl (VO 2+ ) containing compounds, phosphoric acid compounds, cobalt compounds, an organic compound of an inorganic compound or a low molecular weight organic acids.
[0005]
　Recently, chromate-free coating, in addition to conventional primary rust resistance, are required to have a suitable corrosion resistance for a long period of time. Specifically, the chromate-free coating suppresses deterioration in appearance due to the plating layer is corroded white rust is generated performance (hereinafter, referred to as耐白rust resistance) and resistance to rust generated from steel ( hereinafter referred to as耐赤rust resistance) are required.
　The chromate-free coating having suitable corrosion resistance for a long period of time, the organic resin film are known, for example, Patent Document 2, fluorine 0.5 ~ 5at%, containing 0.5 ~ 5at% phosphorus, silica - organic resin composite film is disclosed. Further, Patent Document 3, an organic resin film containing cobalt compounds are disclosed.
[0006]
　On the other hand, as a technique for improving the blackening resistance of the hot-dip galvanized steel sheet, surface treatment of the plating layer using a Co-containing treatment liquid is disclosed in Patent Document 4.
　As another technique for improving the blackening resistance of the hot-dip galvanized steel sheet, the surface treatment of galvanized layer with Co and Zn-containing processing solution is disclosed in Patent Document 5.
CITATION
Patent Document
[0007]
Patent Document 1: WO 2007/123276
Patent Document 2: Japanese Patent 2000-263695 JP
Patent Document 3: Japanese Patent 2008-291350 JP
Patent Document 4: Japanese JP 59-177381 Japanese
Patent Document 5: Japanese Patent Laid-Open 11-200066 discloses
Summary of the Invention
Problems that the Invention is to Solve
[0008]
　For the above-mentioned compound contained in the chromate-free film of Patent Document 1 is readily soluble in a corrosive environment, the corrosive initial exhibits a high degree of corrosion resistance, corrosion resistance after the corrosion has proceeded is insufficient.
　Silica Patent Document 2 - organic resin composite coating is to be effective when provided on galvanized steel sheet containing no Mg. However, silica Patent Document 2 - organic resin composite film, when provided on galvanized steel sheet containing Mg are blackening is insufficient.
　The organic resin film of Patent Document 3, since it is formed by applying a treatment solution containing both a cobalt compound and an organic resin on the plated steel sheet, a cobalt compound are dispersed in an organic resin film. The, it is difficult to obtain a suitable耐赤rust resistance and suitable blackening this case.
[0009]
　Surface treatment of the plating layer using Co as disclosed in Patent Document 4, it is assumed that performing chromate treatment after the surface treatment with Co. Therefore, in the case of forming a chromate-free film after the surface treatment with Co may sufficient characteristics can not be obtained. For example, the galvanized layer containing Mg, surface treated with Co in Patent Document 4, in the case of forming an organic resin film of Patent Document 2 to the upper layer,耐白rust resistance,耐赤rust resistance and it is difficult to suitably all the characteristics of blackening.
　Surface treatment of the galvanized layer due to Co and Zn are disclosed in Patent Document 5, it is assumed that performing chromate treatment after the surface treatment with Co and Zn. Therefore, in the case of forming a chromate-free film after the surface treatment with Co and Zn, sufficient characteristics can not be obtained. For example, the galvanized layer containing Mg, surface-treated with Co and Zn in Patent Document 5, in the case of forming an organic resin film of Patent Document 2 to the upper layer,耐白rust resistance,耐赤rust and it is difficult to suitably all the characteristics of the blackening resistance.
　Above problem, when the Al concentration of the galvanizing layer containing Mg is less than about 1.0%, when there is a high Mg concentration than the Al concentration of the galvanizing layer, and the amount of deposition of plating If high, more likely to become apparent.
[0010]
　As described above, a and chromate-free coating containing Mg galvanized layer, 耐白 rust resistance, the development of superior hot-dip galvanized steel sheet in all 耐赤 rust resistance and blackening resistance is desired.
Means for Solving the Problems
[0011]
　Inventors have made intensive studies, the surface layer of the galvanized layer, the presence of Co precipitates, thereafter, it is an organic resin film, 耐白 rust resistance, the 耐赤 rust resistance and blackening resistance It found to be able to manufacture all excellent galvanized steel sheet.
[0012]
　The present invention is to solve the above problems, adopts the following means in order to achieve the object.
(1) hot-dip galvanized steel sheet according to one embodiment of the present invention includes a steel plate, provided on a surface of the steel sheet, Mg: 0.05 ~ 2.00 wt%, Al: 0.1 wt% to 1.0 less than mass%, Ni: 0.05 contains ~ 2.00% by weight, and galvanized layer the balance being Zn and impurities, provided on a surface of the galvanized layer, in terms of metal Co content 0.1 ~ 2.0 mg / m 2 comprising Co precipitates, and Co-Mg-Zn layer containing Mg and Zn, and an organic resin film provided on an upper layer of the Co-Mg-Zn layer.
[0013]
(2) In the hot-dip galvanized steel sheet according to (1), the galvanized layer further, Li: 0.001 ~ 0.200 wt%, Na: 0.001 ~ 0.200 wt%, K : 0.001 to 0.200 mass%, Ca: 0.001 to 0.200 wt%, Sr: 0.001 to 0.200 mass%, Sc: 0.001 to 0.200 mass%, Y: 0 .001 ~ 0.200 wt%, Ti: 0.001 ~ 0.200 wt%, Zr: 0.001 - 0.200 wt%, Cu: 0.001 - 0.200 wt%, Sn: 0.001 ~ 0.200 wt%, Si 0.001 to 0.200 wt%, mischmetal 0.001 to 0.200 wt%, may contain one or more of.
[0014]
(3) In the hot-dip galvanized steel sheet according to (1) or (2), the organic resin coating contains a phosphate compound, and, V compound, Si compound, one of a Ti compound and a Zr compound it may contain more.
[0015]
(4) The method of producing hot-dip galvanized steel sheet according to another aspect of the present invention is a method of producing a hot-dip galvanized steel sheet according to any one aspect of the above (1) to (3), the steel plate on the surface, Mg: 0.05 to 2.00 wt%, Al: 0.1% by mass to less than 1.0 wt%, Ni: contains 0.05 to 2.00 wt%, the balance being Zn and impurities forming a galvanized layer consisting, in the steel plate having the galvanized layers, 0.1 Co ion ~ 0.5 g / L, Zn ions and 0 of 0.2 ~ 2.0 g / L .1 coating forming a Co-Mg-Zn layer by contacting an acidic aqueous solution containing Mg ion ~ 2.0 g / l, the organic resin film forming solution on the surface of the Co-Mg-Zn layer and, and a step of forming an organic resin film by drying.
[0016]
(5) In the method for manufacturing a galvanized steel sheet according to (4), the concentration of the Co ions contained in the acidic aqueous solution, it is less than the concentration of the Zn concentration below and the Mg ion ion good.
[0017]
(6) In the method for manufacturing a galvanized steel sheet according to (4) or (5), a pH of 1-3 of the aqueous acidic solution, the temperature of the acidic aqueous solution is at 40 ° C. or less, the molten zinc the contact time of the steel sheet having a plating layer and the acidic aqueous solution may be not more than 5 seconds.
Effect of the invention
[0018]
　Galvanized steel sheet of the present invention, 耐白 rust resistance, and all 耐赤 rust resistance and blackening resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
In hot-dip galvanized steel sheet comprising an organic resin film of FIG 1] Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and the blackening resistance.
In hot-dip galvanized steel sheet comprising an organic resin film of FIG. 2] Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and耐白rust resistance.
[3] In hot-dip galvanized steel sheet comprising an organic resin film of Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and耐赤rust resistance.
In hot-dip galvanized steel sheet and a [FIG 4] Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and the blackening resistance.
In hot-dip galvanized steel sheet and a [FIG 5] Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and耐白rust resistance.
In hot-dip galvanized steel sheet and a [FIG 6] Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and耐赤rust resistance.
7 is a schematic view showing a layer structure of a galvanized steel sheet according to the present embodiment.
8 is a graph showing the results when analyzing the galvanized steel sheet according to the present embodiment by GDS.
The FIG 9] GDS, is a graph showing the results when analyzing the galvanized steel sheets in the case of forming an organic resin film containing Co in galvanized layer.
DESCRIPTION OF THE INVENTION
[0020]
　Hereinafter, a galvanized steel sheet and a manufacturing method thereof according to the embodiment will be described with reference to the drawings.
　Unless otherwise specified, "%" means "% by mass".
(Galvanized steel sheet 10)
　will be described first galvanized steel sheet 10 of the present embodiment.
　Figure 7 is a schematic view showing a layer structure of a galvanized steel sheet 10 of the present embodiment. As shown in FIG. 7, galvanized steel sheet 10 includes a steel plate 1, provided on the surface of the steel sheet 1, Mg: 0.05 ~ 2.00 wt%, Al: 0.1 wt% to 1.0 wt less than%, Ni: contains 0.05 to 2.00 wt%, the galvanized layer 3 and the balance being Zn and impurities, provided on the surface of the galvanized layer 3, in terms of metal Co content 0.1 ~ 2.0 mg / m 2 and Co-Mg-Zn layer 5 containing Co precipitates 4, MG6 and Zn8, an organic resin film 7 provided on an upper layer of Co-Mg-Zn layer 5, equipped with a.
[0021]
　
　steel 1 to be used for hot-dip galvanized steel sheet 10 is not particularly limited, it is possible to use a steel sheet used in the normal galvanized steel sheet. The steel plate 1 of the manufacturing method and material, etc. is not particularly limited, hot rolling from a conventional billet manufacturing processes, pickling, cold rolling, annealing, and only needs to be manufactured through the temper rolling or the like process .
[0022]
　
　galvanized layer 3 is provided on the surface of the steel sheet 1, Mg: 0.05 ~ 2.00 wt%, Al: 0.1% by mass to less than 1.0 wt%, Ni: It contains 0.05 to 2.00 wt%, the balance being Zn and impurities.
　Galvanized layer 3 is further, Li, Na, K, Ca , Sr, Sc, Y, Ti, Zr, Cu, Sn, Si, misch respectively 0.200 mass one or more elements such as metal % or less, preferably from 0.001 to 0.200 wt%, and more preferably may contain from 0.001 to 0.100 wt%. Of the above-mentioned elements, especially to equalize the solidification of the molten zinc plated layer 3 in the case of thick basis weight, appearance and the blackening resistance, corrosion resistance, in particular contributes to耐白rust resistance and耐赤rust resistance improvement.
　Galvanized layer 3, except to inevitably mixed in the production process, and containing no Co.
[0023]
　Mg in less than 0.05%, while the blackening resistance and 耐白 rust resistance is good, undesirably 耐赤 rust resistance is lowered. Mg in addition to the appearance tends to deteriorate when it exceeds 2.00%, undesirably blackening and 耐白 rust resistance is lowered. Therefore, a 0.05 to 2.00% of Mg. A more preferred range of Mg concentration is from 0.30 to 1.00%.
[0024]
　Al in less than 0.1 percent, by developing the Zn-Fe alloy layer at the interface between the steel sheet 1 and the galvanized layer 3 is not preferred because耐赤rust resistance is lowered. Al to be a more than 1.0%, it is difficult to increase the adhesion amount of hot-dip galvanizing layer 3 is not preferable because it may耐赤rust resistance is lowered. Therefore, the Al is less than 0.1 to 1.0%.
　The upper limit of the Al concentration is preferably 0.85%, 0.8%, 0.75%, may be 0.5%. The lower limit of the Al concentration is preferably 0.2%, more preferably 0.25%.
[0025]
　If the galvanized layer 3 containing Mg, Mg enrichment section (not shown) is likely to occur in the vicinity of the surface of the galvanized layer 3. That is, when viewed galvanized layer 3 in the depth direction, Mg concentration in the vicinity of the surface is higher than the interior. Further, Mg has a high ionization tendency than Fe and Zn in the steel sheet 1, there is a tendency (sacrificial protection effect) leach before the Fe and Zn. If galvanized layer 3 containing Mg, by a sacrificial protection effect of uneven localization and Mg of Mg regarding the depth direction, Mg is locally eluted and blackening resistance and 耐白 rust resistance decreases Presumed.
[0026]
　Decrease in resistance to blackening and耐白rust resistance described above is remarkable when the Al concentration of the galvanizing layer 3 is lower than the Mg concentration.
　When the Al concentration in molten zinc plating layer 3 is higher than the Mg concentration is at least one of the Al phase and Zn-Al-Mg Sangentomo phase is formed in the galvanized layer 3. In these tissues, sacrificial protection effect of Mg in the influence of passivation effect of Al is assumed to be alleviated.
　On the other hand, in galvanized layer 3, when the Al concentration is lower than the Mg concentration, sacrificial protection effect of Mg it becomes stronger than the passivation effect of Al. Therefore, by the uneven localization of Mg relates sacrificial protection effect and the depth direction of the Mg, blackening resistance and耐白rust resistance is estimated to be likely to decrease.
　Further, the effect of sacrificial protection effect of Mg, when adhered with Co in the surface layer of the galvanized layer 3, deposited Co is unevenly distributed prone. This is also estimated a factor of lowering the blackening resistance and corrosion resistance.
[0027]
　In less than 0.05% Ni content of galvanized layer 3 is not preferable because it becomes difficult to achieve both the blackening resistance and耐白rust resistance. The Ni content of galvanized layer 3 is more than 2.00%, the appearance of the galvanized layer 3 is easily deteriorated, also not preferred because耐赤rust resistance is lowered. Therefore, a 0.05 to 2.00% of Ni. A more preferable range of Ni content of the galvanized layer 3 is 0.10 to 1.00%.
　Is galvanized layer 3 by containing Ni in addition to Mg, it is considered possible to alleviate the uneven distribution of Mg regarding the depth direction.
[0028]
　The content of each element contained in the galvanized layer 3 can be measured by wet ICP-MS method.
[0029]
　Adhesion amount of hot-dip galvanizing layer 3, from the viewpoint of suitably securing the耐赤rust, per side 150 g / m 2 or more, preferably 200 g / m 2 or more, more preferably 300 g / m 2 is at least. By thus increasing the adhesion amount, for example, it is possible to ensure耐赤rust of level red rust is not generated SST2000 hours or more.
　Adhesion amount of hot-dip galvanizing layer 3 is not limited to the amount of deposition of the, even if less than the adhesion amount of the, by the required level of耐赤rust resistance can be used. Since the compatibility between resistance to blackening and耐白rust resistance is difficult when particularly large amount of adhering hot-dip galvanized layer 3 in the prior art, the effect of the present invention if the adhesion amount of hot-dip galvanizing layer 3 is large It becomes more pronounced.
　The upper limit of the coating weight of hot-dip galvanizing layer 3 is not particularly limited, consider the 600 g / m realistic manufacturability 2 is about.
[0030]
　
　galvanized steel sheet 10, the upper layer of the galvanized layer 3, in terms of metal Co amount 0.1 ~ 2.0 mg / m 2 Co precipitates 4, MG6 and comprising a Co-Mg-Zn layer 5 containing Zn8.
　Co-Mg-Zn layer 5 contains a a Co precipitates 4 deposited on the surface of the galvanized layer 3 MG6 and Zn8. As shown in FIG. 7, Co-Mg-Zn layer 5 is coated with a part of the surface of the galvanized layer 3, Co-Mg-Zn layer is part of the surface of the galvanized layer 3 5 depending presumably uncoated.
[0031]
　Co precipitate was deposited on galvanized layer 3 4 is present stably in the Co-Mg-Zn layer 5. The Co precipitates 4 are present this stable and suitable adhesiveness is exhibited between the galvanized layer 3 and the organic resin film 7, excellent耐白rust of the steel sheet of the present invention,耐赤rust It is considered to lead to sex and blackening resistance.
　Co precipitates 4 contained in the Co-Mg-Zn layer 5 is a metal Co, it may be any of Co oxide and hydroxide Co.
[0032]
　Co content of Co-Mg-Zn layer 5 is in terms of metal Co 2.0 mg / m 2 when is greater than耐白rust resistance decreases. Therefore, the upper limit of the Co content of Co-Mg-Zn layer 5, 2.0 mg / m 2 is. The upper limit of the Co content of Co-Mg-Zn layer 5 is preferably 1.0 mg / m 2 is.
　Co content of Co-Mg-Zn layer 5, 0.1mg / m which is the detection limit 2 is exhibit sufficient blackening effect in order, the lower limit of the Co content in the present embodiment 0.1mg / M 2 defined as.
　Therefore, Co content of Co-Mg-Zn layer 5 is 0.1 ~ 2.0 mg / m 2 is preferably 0.1 ~ 1.0 mg / m 2 is.
　Co content can be measured by a wet ICP-MS method.
[0033]
　The Co-Mg-Zn layer 5 is formed between the galvanized layer 3 and the organic resin film 7 can be confirmed by using a GDS (glow discharge optical emission spectrometer).
　Figure 8 is a graph showing the results of analysis by GDS of galvanized steel sheet 10 of the present embodiment. 9, in the case of forming the organic resin film containing Co in galvanized layer (that is, if no Co-Mg-Zn layer), a graph showing the results of analysis by GDS of galvanized steel sheet it is.
[0034]
　8 and 9, the location of C represents the depth position of the organic resin film 7 is formed, the location of the Co represents the depth position of Co-Mg-Zn layer 5 is formed, Mg and the location of the Zn represents a depth position where the galvanized layer 3 is formed.
　From the results shown in FIG. 8, it can be seen that Co-Mg-Zn layer 5 is formed between the galvanized steel sheet 10, an organic resin film 7 and the galvanized layer 3. On the other hand, from the results shown in FIG. 9, when the Co-Mg-Zn layer 5 is not formed, the peak of Co between the organic resin film 7 and the galvanized layer 3 is not detected, the peak of the Co it is largely consistent with the peak of C (that is, Co is dispersed in an organic resin film 7) can be seen.
[0035]
　Mg content of Co-Mg-Zn layer 5 and the Zn content, if it can be present stably Co precipitates 4 is not particularly limited.
[0036]
　
　galvanized steel sheet 10 has an organic resin coating 7 on the upper layer of the Co-Mg-Zn layer 5.
[0037]
　Examples of the organic resin contained in the organic resin film 7, polyolefin resins, urethane resins, acrylic resins, epoxy resins, polyester resins.
　The content of the organic resin in the organic resin film 7 is any content is not particularly limited.
[0038]
　These organic resins, to enhance the barrier properties of the organic resin film 7, enhanced especially long corrosion products after the holding effect of the (white rust), has an effect of improving the耐赤rust resistance. Further, the organic resin, the outermost layer of the galvanized layer 3 after Co-Mg-Zn layer 5 is formed by a stable action of the Co precipitates 4 are present, the blackening resistance and corrosion resistance it is estimated that an effect of improving.
　The organic resin film 7 is formed at FT-IR method, it can be confirmed by observing the organic resin specific peak. It organic resin film 7 is chromate free, it can be confirmed by composition analysis of the organic resin film 7 (e.g., a physical analysis of the chemical analysis or GDS such as wet ICP-MS method). By the above analysis, if the Cr is below the detection limit of less than or background level, the organic resin film 7 is evaluated as chromate-free.
[0039]
　The organic resin film 7, an organic resin as a main component preferably further contains a phosphate compound.
　Examples of phosphoric acid compounds, phosphoric acid and its salts, pyrophosphoric acid and salts thereof, metaphosphoric acid and salts thereof, polyphosphoric acid and its salts, phytic acid, phosphonic acid compounds. Examples of phosphonic acid compounds, such as 1-hydroxyethylidene-1,1-diphosphonic acid.
[0040]
　Phosphate compounds, the Zn ions and Mg ions generated corrosion initial by precipitation as a sparingly soluble salt, it has the effect of improving the耐白rust resistance. Further, phosphoric acid compound in the organic resin film 7, and the outermost layer, in particular some interaction with the uppermost layer of the galvanized layer 3 after Co-Mg-Zn layer 5 is formed of a galvanized layer 3 easy, whereby it is estimated that an effect of improving the blackening resistance and corrosion resistance.
　The content of phosphoric acid compound in the organic resin film 7 is arbitrary and is not particularly limited.
[0041]
　The organic resin film 7, in addition to the organic resin and the phosphoric acid compound, further, V compound, Si compound, preferably contains more than one kind selected from the group consisting of Ti compound and Zr compound.
[0042]
　Examples of V compounds, vanadium pentoxide, metavanadate and salts thereof, polyvanadic acid and its salts, vanadium trioxide, vanadium dioxide, vanadyl oxalate, vanadium oxy acetylacetonate, vanadium acetylacetonate, include acetic and vanadium It is.
　V compound Like the phosphate compound, by precipitation of Zn ions and Mg ions generated corrosion early as a sparingly soluble salt, has the effect of improving the耐白rust resistance. The mechanism is not clear, the effect of improving耐白rusting due V compound is noticeable when the V compound and the phosphate compound coexist.
[0043]
　The content of V compound in an organic resin film 7 is arbitrary and is not particularly limited.
[0044]
　Examples of Si compound, silica, silicates, silane coupling agents.
　Examples of silica, aqueous dispersion is preferably such as colloidal silica, Snowtex C, Snowtex O, Snowtex N (or more, manufactured by Nissan Chemical Industries) or the like can be used. Examples of silicate, Na-silicate, Li silicates, such as K silicates and the like.
[0045]
　Examples of the silane coupling agent, vinyl silane, vinyl trimethoxysilane, vinyl triethoxysilane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane, N-(1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N, N'-bis (3- (trimethoxysilyl ) propyl) ethylenediamine, N-(beta-aminoethyl)-.gamma.-aminopropyl methyl dimethoxysilane, N-(beta-aminoethyl)-.gamma.-aminopropyltrimethoxysilane, .gamma.-aminopropyltrimethoxysilane, .gamma.-amino aminopropyltriethoxysilane, .gamma. glycine Trimethoxysilane, .gamma.-glycidoxypropyl triethoxysilane, .gamma.-glycidoxypropyl methyl dimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, .gamma.-methacryloxypropyl trimethoxysilane, .gamma.-methacryloxypropyl triethoxy silane, .gamma.-mercaptopropyltrimethoxysilane, .gamma.-mercaptopropyl triethoxysilane, N- and the like (2- (vinylbenzylamino) ethyl) -3-aminopropyltrimethoxysilane it can, can also be used these polycondensates.
[0046]
　The content of Si compound in an organic resin film 7 is optional and not particularly limited.
[0047]
　Examples of the Ti compound, titanium acetate, titanium carbonate, tetraisopropyl titanate, titanium acetyl acetonate, titanium tetraacetyl acetonate, titanium lactate, titanium triethanol aluminate, titanium diethanolamine titanate, titanium-aminoethylamino ethanolate, shook titanium hydrogen acid, and titanium ammonium fluoride and the like.
　The content of Ti compound in an organic resin film 7 is optional and not particularly limited.
[0048]
　Examples of Zr compounds, zirconyl acetate, zirconyl ammonium carbonate, n-propyl zirconate, zirconium tetraacetyl acetonate, zirconium ethyl acetoacetate, zirconium stearate, zirconium lactate ammonium, zirconium hydrofluoric acid, zirconium ammonium fluoride and the like and the like.
　The content of Zr compound in an organic resin film 7 is optional and not particularly limited.
[0049]
　Si compounds, Ti compounds, any Zr compound reinforcing the barrier properties of the organic resin film 7, an effect of improving both耐白rust resistance and耐赤rust resistance.
　The content of these components in the organic resin film 7 can be measured by GDS.
[0050]
　The organic resin film 7, in addition to the above-mentioned compounds, may contain a wax in order to improve the sliding properties and the like. Further, the organic resin film 7, in order to further improve the corrosion resistance, may contain a rust inhibitor. Further, the organic resin film 7, in order to improve or adjust the appearance, pigments, dyes, pigments, may contain a surfactant or the like.
[0051]
　The thickness of the organic resin film 7, 0.1μm ~ 10.0μm, preferably, 0.3μm ~ 3.0μm, more preferably from 0.5 [mu] m ~ 2.0 .mu.m. When the thickness of the organic resin film 7 is smaller than 0.1μm it is also not preferable that the corrosion resistance is insufficient. Further, when the thickness of the organic resin film 7 is 10.0μm than not only the cost is increased, unfavorably, sometimes welding becomes difficult.
　The thickness of the organic resin film 7, a sample embedded polished vertical measuring the thickness can be measured by SEM observation.
[0052]
　(Method of manufacturing a galvanized steel sheet 10)
　Next, a method for manufacturing a galvanized steel sheet 10.
　
　method for forming a hot-dip galvanizing layer 3 on the steel plate 1 is not particularly limited, redox method, total reducing method, any known melt plating method such as pre-plating method can be used .
[0053]
　Is galvanized layer 3 to adjust the plating bath concentration such that the chemical composition described above. Comparing with the chemical composition of the plating bath and the chemical composition of the molten zinc plated layer 3, Mg and Ni in both chemical composition is approximately equal, Al is the chemical composition of the galvanized layer 3 than the chemical composition of the plating bath there is a slightly greater tendency towards. Further, since the Ni concentration soluble in the plating bath is a about 0.1% at most, in the case to contain no more Ni in galvanized layer 3 is preferably performed hot dipping after pre-plating of Ni .
　After formation of the galvanizing layer 3 may be subjected to temper rolling as required. This makes it possible to adjust the surface roughness and appearance.
[0054]
　
　After forming the hot-dip galvanizing layer 3, or after having been subjected to temper rolling, to the surface of the galvanized layer 3, using Co ion-containing acidic aqueous solution perform flash processing. Thus, on the galvanized layer 3, in terms of metal Co amount 0.1 ~ 2.0 mg / m 2 to form a Co-Mg-Zn layer 5 containing Co precipitates 4, MG6 and Zn8 of .
[0055]
　Co ion-containing acidic aqueous solution, a Co ion 0.1 ~ 0.5g / L, Zn ions 0.2 ~ 2.0 g / L, the Mg ion containing 0.1 ~ 2.0g / l.
　Galvanized layer 3, since the content of Al is small, it is estimated that a high reactivity with an acidic aqueous solution. Therefore, in the case of using an alkaline aqueous surface conditioner not attached amount of Co precipitates 4 is stabilized, it may be difficult to obtain a suitable corrosion resistance and blackening resistance.
[0056]
　Is less than Co ions 0.1 g / L in Co ion-containing acidic aqueous solution, may Co does not adhere not stable. Further, when the Co ions Co ion-containing acidic aqueous solution is more than 0.5 g / L, which is not preferable if the amount of deposition of Co precipitates 4 is excessive.
　The Zn ion is less than 0.2 g / L, since the Co precipitates 4 is not stabilized, adhesion state of Co precipitates 4 tends to be uneven. When Zn ions exceeds 2.0 g / L, there is a case where stains are generated on the surface of the galvanized layer 3 is not preferable.
　The Mg ion is less than 0.1 g / L, since the Co precipitates 4 is not stabilized, adhesion state of Co precipitates 4 tends to be uneven. When Mg ions exceeds 2.0 g / L, there is a case where stains are generated on the surface of the galvanized layer 3 is not preferable.
[0057]
　The galvanized layer 3, Co ions, is brought into contact with Co ion-containing acidic aqueous solution containing Zn ions and Mg ions, the most active Mg thickening unit reaction in galvanized layer 3, here, Co , Zn, metals including Mg, oxide, or believed hydroxide precipitates. That is, Zn and Mg also part eutectoid in Co ion-containing acidic aqueous solution is thereby estimated to contribute to stabilization of the performance of deposited amount and Co-Mg-Zn layer 5 of Co. Not the Co ion-containing acidic aqueous solution only Co ion, by addition of Zn ions and Mg ions, is that an effect is obtained as described above, it was first discovered by the present invention.
　Co and Zn, a metal, has been deposited in the form of an oxide or hydroxide, Mg is considered to be precipitated in the form of an oxide or hydroxide. However, a precipitation amount of these compounds is very small amount, and the lower layer of the molten zinc plated layer 3 of the Co-Mg-Zn layer 5 from include Zn and Mg, not possible to identify these compounds It was.
[0058]
　Co ions contained in Co ion-containing acidic aqueous solution, Zn ions, Mg ions, can be used sulfates, chlorides, nitrates and the like. Co ions, Zn ions, as Mg ions, to use a phosphate salt and fluoride are not preferred.
[0059]
　The Co ion-containing acidic aqueous solution is good other ions be contained include Al ions (aluminate ions). Since Al ions does not affect the precipitation behavior of Co, Co ion-containing acidic aqueous solution may contain Al ions.
　Co ion-containing acidic aqueous solution may contain a Fe ion, but because Fe ions tend to decrease the corrosion resistance of galvanized steel sheets 10, Fe ion concentration of Co ion-containing acidic aqueous solution is 0.1 g / L or less preferably limited to.
[0060]
　To control Co-Mg-Zn layer 5 in a stable manner, it is preferable to increase the concentration of Zn ions than the concentration of Co ions in the Co ion-containing acidic aqueous solution. Similarly, than the concentration of Co ions in the Co ion-containing acidic aqueous solution, it is preferable to increase the concentration of Mg ions.
　In Co ion-containing acidic aqueous solution, by increasing the concentration of Zn ions than 2 times the concentration of Co ions and the Mg ion concentration is more preferably larger than Co ion concentration.
[0061]
　pH of Co ion-containing acidic aqueous solution is 1 to 3, the temperature of the Co ion-containing acidic aqueous solution is 40 ° C. or less, that the contact time between the galvanized layer 3 and the Co ion-containing acidic aqueous solution is less than 5 seconds, Co- more preferable from the viewpoint of stabilizing the mg-Zn layer 5. Method of contacting a Co ion-containing acidic aqueous solution to galvanized layer 3 is not particularly limited, such as dipping method or spraying method is exemplified.
[0062]
　 After the formation of the Co-Mg-Zn layer 5, washed with water and dried so. Then, by coating an organic resin film formation solution having a chemical composition as described above, by drying, to form an organic resin film 7. The method of coating and drying are not particularly limited.
Example
[0063]
　Next, Examples and Comparative Examples further illustrate the present invention.
　
　The characteristics of the present invention will be described with reference to FIGS. With hot-dip galvanized steel sheet of the three kinds of plating composition produced in a continuous galvanizing line. The composition of the plating, the following three types, both coating weight 250 g / m 2 was used in the (per Incidentally,% represents mass%.
(1) Al: 0.2%, Mg: 0.5%, Ni: 0.1%, the balance Zn and inevitable impurities (with Zn-0.2Al-0.5Mg-0.1Ni
notation) (2) Al: 0.2%, Mg: 0.5 %, the balance Zn and inevitable impurities (Zn-0.2Al-0.5Mg
denoted) (3) Al: 0.2%, the balance Zn and inevitable impurities ( referred to as Zn-0.2Al)
[0064]
　The molten zinc plated steel sheet produced above was subjected to treatment with Co ion-containing acidic aqueous solution. Co ion-containing acidic aqueous solution, was used C or J in Table 1.
　The upper layer of the Co-Mg-Zn layer to form a chromate film or an organic resin film. The organic resin film is used a1 in Table 2, the thickness of the organic resin film was 1 [mu] m. Chromate film, reducing chromic acid, (Cr coating weight 58 mg / m corresponding to Inventive Example 6 of Table 1 of Japanese KOKOKU 4-20992 discloses a typical chromate film comprising silica and phosphoric acid 2 chromate coating) It was used.
[0065]
　Using the above molten zinc plated steel sheet was examined blackening resistance,耐白rust resistance and耐赤rust resistance.
　Blackening resistance was measured as follows. First, it superimposed to face the evaluation surface of the galvanized steel sheet (surface of the organic resin film) was packed (the galvanized steel sheet after packing is referred to as blackening test piece). Then, holding one week blackening specimen under 70 ° C. 85% RH environment, the brightness change before and after holding ([Delta] L * was measured). In the case of brightness change is 3.0 or less was acceptable.
[0066]
　耐白rust resistance was measured as follows. That, SST as defined in JISZ2371 to galvanized steel sheet (salt spray test) carried out 72 hours, were quantified white rust area ratio. White rust area ratio was as acceptable if: 5.0%.
　耐赤rust resistance was measured as follows. First, referred to as outermost layer from the galvanized layer to reach the formation of the cross-cut flaw (crosscut molten zinc flaw was formed plated steel sheet a耐赤rust test piece (organic resin film outermost surface of) the hot-dip galvanized steel sheet ). Next, the耐赤rust test piece was subjected to 2000 hours SST as specified in JISZ2371 (salt spray test). Red rust was as acceptable if you did not occur.
[0067]
　The results obtained by the above, as shown in FIGS. 1-6.
　1, the galvanized steel sheet provided with an organic resin film of Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and the blackening resistance. Figure 2 is the galvanized steel sheet with an organic resin film of Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and耐白rust resistance. 3, the hot-dip galvanized steel sheet having an organic resin film of Co-Mg-Zn layer and the chromate-free, is a graph showing the relationship between the Co deposition amount and耐赤rust resistance.
　Figure 4 is the hot-dip galvanized steel sheet comprising a Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and the blackening resistance. Figure 5 is the hot-dip galvanized steel sheet comprising a Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and耐白rust resistance. 6, in the hot-dip galvanized steel sheet comprising a Co-Mg-Zn layer and the chromate film is a graph showing the relationship between the Co deposition amount and耐赤rust resistance.
[0068]
　If galvanized steel sheet having an organic resin film of Co-Mg-Zn layer and the chromate-free, as can be seen from Figure 1, Figure 2, with increasing Co deposition amount, while improving the blackening resistance,耐白rust resistance is lowered, it can be seen that the blackening resistance and耐白rust resistance are in a trade-off relationship.
　As shown in Figures 1 and 2, in the case of Zn-0.2Al-0.5Mg it can be varied Co deposition amount, to pass both the blackening resistance and耐白rust it could not be.
[0069]
　On the other hand, as shown in Figures 1 and 2, in the case of Zn-0.2Al-0.5Mg-0.1Ni is the Co deposition amount 2.0 mg / m 2 as well as below, the organic resin film by using, I was able to pass both the blackening resistance and耐白rust resistance.
　In the case of Zn-0.2Al containing no Mg, as shown in FIG. 1 and 2, although Co deposition amount both is passing the blackening resistance and耐白rust are present, Figure 3 as shown in,耐赤rust resistance was unacceptable in those Co deposition amount.
[0070]
　When the galvanized steel sheet has a chromate film, as shown in FIGS. 4 and 5 were able to both the blackening resistance and 耐白 rust pass by increasing the Co deposition amount. However, as shown in FIG. 6, in those Co deposition amount, galvanized layer also contain Mg, 耐赤 rust resistance was unacceptable.
[0071]
　As described above, Zn-0.2Al-0.5Mg-0.1Ni using, Co deposition of Co-Mg-Zn layer formed between the galvanized layer and an organic resin film as the hot dip galvanized layer the amount 0.1 ~ 2.0 mg / m 2 and, by using an organic resin film of the chromate-free upper layer of Co, obtained characteristics that satisfy all of the blackening resistance and耐白rust and耐赤rust it has been shown to be.
[0072]
　
　In Table 1 to Table 5, numerical values outside the scope of the present invention are underlined in the field.
[0073]
　(Examples 1-31 and Comparative Examples 1-7)
　about 250 g / m per weight deposited one side 2 , the chemical composition, Mg: 0.5%, Al: 0.2%, Ni: 0.1%, balance It was subjected to temper rolling the steel sheet having a galvanized layer of Zn and unavoidable impurities.
[0074]
　Thereafter, the surface of the galvanized layer, a spray process using a Co ion-containing acidic aqueous solution of 40 ° C. were conducted 1-3 seconds. This was followed by washing and drying.
　Table 1 shows the composition of a Co ion-containing acidic aqueous solution. Both were dissolved sulfate, pH was adjusted with sulfuric acid.
[0075]
　Next, a chromate-free organic resin is applied to form an organic resin film by drying.
　The organic resin film is used as shown in Table 2. The aqueous coating composition was formulated so that the solid content concentration shown in Table 2 was applied with a bar coater to form a coating baked at 100 ° C. in a hot air drying oven. The thickness of the coating was adjusted to either be 1 [mu] m.
　In some comparative examples, it was used a film other than the organic resin film.
[0076]
　Co amount was quantified by wet ICP-MS method, and displayed in the table at the metal basis weight.
　In Comparative Example 4-6 did not form a Co-Mg-Zn layer.
[0077]
　Performance evaluation was carried out in the following manner.
　(Blackening)
　First, it superimposed to face the evaluation surface of the galvanized steel sheet was packed (the galvanized steel sheet after packing is referred to as blackening test piece). Then, holding one week blackening specimen under 70 ° C. 85% RH environment, to measure the brightness change before and after holding ([Delta] L *). In the case of brightness change is 3.0 or less was acceptable.
[0078]
　(耐白rust resistance)
　耐白rust resistance was measured as follows. That, SST as defined in JISZ2371 to galvanized steel sheet (salt spray test) carried out 72 hours, were quantified white rust area ratio. White rust area ratio was as acceptable if: 5.0%.
[0079]
　(耐赤rust resistance)
　耐赤rust resistance was measured as follows. First, referred to as outermost layer from the galvanized layer to reach the formation of the cross-cut flaw (crosscut molten zinc flaw was formed plated steel sheet a耐赤rust test piece (organic resin film outermost surface of) the hot-dip galvanized steel sheet ). Next, the耐赤rust test piece was subjected to 2000 hours SST as specified in JISZ2371 (salt spray test). Red rust was as acceptable if you did not occur.
[0080]
　Table 3 shows the conditions and evaluation results of Examples 1 to 31 and Comparative Examples 1-7.
　As shown in Table 3, Examples 1-31 showed good properties.
[0081]
　On the other hand, Comparative Examples 1 to 3, Co deposition amount is due to exceeding the scope of the present invention,耐白rust resistance was unacceptable.
　Comparative Example 1 uses a J in Table 1 as Co ion-containing acidic aqueous solution, in addition to Co ions is excessive, since the Co ion-containing acidic aqueous solution does not contain Zn ion and Mg ion, galvanized steel sheet adhesion amount of Co is considered to become excessive.
[0082]
　Comparative Example 2 uses a K of Table 1 as a Co ion-containing acidic aqueous solution, in addition to Co ions is excessive, since the Co ion-containing acidic aqueous solution containing no Mg ions, Co deposition amount becomes excessive It is considered to have. In Comparative Example 2, the blackening resistance also have failed.
　Comparative Example 3 is used L in Table 1 as Co ion-containing acidic aqueous solution, since Co ions were excessive, believed Co deposition amount becomes excessive. Comparative Example 3 also, blackening was bad and unacceptable in addition to耐白rust resistance.
　Comparative Example 4 because it was not adhered to Co, blackening was rejected.
[0083]
　In Comparative Example 5, similarly to Patent Document 3, without forming a Co-Mg-Zn layer, it has formed the organic resin film containing Co, blackening resistance and耐赤rust resistance was unacceptable. Co precipitates without precipitation at the interface between the organic resin film galvanized layer, due to which has been dispersed throughout the organic resin film, suitable blackening is considered to not be obtained.
　Comparative Example 6, but is obtained by directly formed organic resin film on the upper layer of the galvanized layer, suitable blackening was not obtained.
[0084]
　Comparative Example 7, but is obtained by forming a chromate film in place of the organic resin film, and the blackening resistance and 耐赤 rust resistance was unacceptable.
[0085]
[Table 1]

[0086]
[Table 2]

[0087]
[table 3]

[0088]
　(Examples 32 to 45 and Comparative Examples 8 to 11)
　the hot-rolled steel sheet has been pickled and original plate, thereby forming a galvanized layer having the composition shown in Table 4. In forming a galvanized layer having the composition shown in Table 4, at hot dipping simulator, Mg, Al, changing the Ni concentration and trace additives components. In some simulations, it was used which has been subjected to Ni pre-plating.
　Adhesion amount of hot-dip galvanizing layer, 0.99 ~ 220 g / m 2 was. Thereafter, the Co ion-containing acidic aqueous solution A of Table 1, the steel plates forming the galvanized layer, by immersing for 5 seconds at a temperature of 30 ° C., was deposited Co at a coverage shown in Table 4. Then, to form a chromate-free organic resin film of Table 2 a1 a thickness of 1 [mu] m.
　The evaluation was carried out in the same manner as in Examples 1 to 31 and Comparative Examples 1-7, but for耐赤rust resistance was evaluated耐赤rust by occurrence of red rust at the time of performing the SST 1500 hours.
[0089]
　As shown in Table 4, Examples 32 to 45 exhibited good characteristics.
　Here, in Examples 32 and 35-38, among various conditions, are different only Mg content of galvanized layer. As apparent from the evaluation results of blackening of these embodiments, blackening was different by Mg content of galvanized layer.
[0090]
　On the other hand, in Comparative Example 8, since the hot-dip galvanizing layer contains no Mg and Ni,耐赤rust resistance was unacceptable.
　In Comparative Example 9, since the hot-dip galvanizing layer contains no Ni, blackening resistance and耐白rust resistance was unacceptable.
　In Comparative Examples 10 and 11, are excessive Al content of galvanized layer, and the blackening resistance and耐赤rust resistance was unacceptable.
[0091]
[Table 4]

[0092]
　(Examples 46-48 and Comparative Example 12)
　in a continuous galvanizing line, galvanizing, temper rolling was performed continuously processed by the Co ion-containing acidic aqueous solution.
　Galvanizing is about 300 g / m deposition amount per side 2 , the composition of the plating bath, Mg: 0.5%, Al: 0.3%, Ni: 0.07%, in the balance Zn and unavoidable impurities there were.
[0093]
　Next, spray treatment with Co ion-containing acidic aqueous solution having a concentration shown in Table 5. 3-5 seconds. Incidentally, the counter anion is a sulfate ion, pH was adjusted with sulfuric acid. The bath temperature was 30 ~ 35 ℃.
　Plated steel sheet produced, front and back, the width direction, longitudinal direction, and a total of 30 points sampled by wet ICP-MS method, to measure the Co deposition amount.
[0094]
　Table 5, the measurement results of the Co deposition amount, minimum, maximum, average, exhibited a standard deviation (sigma). As shown in Table 5, in Examples 46-48 was less variation in each part of the Co deposition amount. In particular, the Co ion-containing acidic aqueous solution, large Zn ion concentration than Co ion concentration, and, when the Mg ion concentration than Co ion concentration greater, it became clear that variations in the Co deposition amount is small.
　Note that the upper layer of Examples 46-48, to form a chromate-free organic resin film of Table 2 a1 was subjected to various performance evaluation, all exhibited good characteristics.
[0095]
　On the other hand, Co ion-containing acidic aqueous solution in Comparative Example 12 since containing no Zn ions and Mg ions, the number of Co deposition amount and the variation was also large.
[0096]
[table 5]

Industrial Applicability
[0097]
　According to the above embodiment, it is possible to provide a 耐白 rust resistance, 耐赤 rust resistance and 耐黒 good galvanized steel sheet and a manufacturing method thereof in all modified.
DESCRIPTION OF SYMBOLS
[0098]
　1 steel plate
　3 galvanized layer
　4 Co precipitates
　5 Co-Mg-Zn layer
　6 Mg
　7 organic resin film
　8 Zn
　10 galvanized steel sheet

claims

[Claim 1]Steel plate and;provided on a surface of the steel sheet, Mg: 0.05 to 2.00 wt%, Al: 0.1% by mass to less than 1.0 wt%, Ni: 0.05 to 2.00 wt% contained, the balance being galvanized layer and consisting of Zn and impurities;
　provided on a surface of the galvanized layer, in terms of metal Co amount 0.1 ~ 2.0 mg / m 2 Co precipitates, Mg and the Co-Mg-Zn layer containing Zn;
　; and the organic resin coating provided on an upper layer of the Co-Mg-Zn layer
comprises a
galvanized steel sheet, characterized in that.
[Claim 2]
　The galvanized layer
further, Li: 0.001 ~ 0.200
wt%, Na: 0.001 ~ 0.200
wt%, K: 0.001 ~ 0.200
wt%, Ca: 0.001 ~ 0.200
wt%, Sr: 0.001 - 0.200
wt%, Sc: 0.001 ~ 0.200
wt%, Y: 0.001 - 0.200
wt%, Ti: 0.001 ~ 0 .200
wt%, Zr: 0.001 ~ 0.200 wt%,
Cu: 0.001 ~ 0.200
wt%, Sn: 0.001 ~ 0.200
wt%, Si: 0.001 ~ 0.200 wt%,
mischmetal: 0.001 to 0.200 mass%
containing one or more of the
hot-dip galvanized steel sheet according to claim 1, characterized in that.
[Claim 3]
　The organic resin coating contains a phosphate compound, and, V compound, Si compound, containing one or more of Ti compound and Zr compound
melting of claim 1 or claim 2, characterized in that zinc-plated steel plate.
[Claim 4]
　A method of manufacturing a galvanized steel sheet according to any one of claims 1 to 3,
　the surface of the steel sheet, Mg: 0.05 ~ 2.00 wt%, Al: 0.1 wt% or more ; containing 0.05 to 2.00 wt%, the balance process and to form a galvanized layer composed of Zn and impurities: less than 1.0 wt%, Ni
　in the steel sheet having the galvanized layers, Co ions 0.1 ~ 0.5g / L, by contacting an acidic aqueous solution containing Mg ion and Zn ion and 0.1 ~ 2.0 g / l of 0.2 ~ 2.0g / L Co- forming a mg-Zn layer;
　organic resin film forming solution was coated on the surface of the Co-mg-Zn layer, forming an organic resin film by drying;
having
, characterized in that melting method of manufacturing a galvanized steel sheet.
[Claim 5]
　The concentration of Co ions, wherein less than the concentration of density less than and the Mg ion Zn ions contained in the acidic aqueous solution
producing method of hot-dip galvanized steel sheet according to claim 4, characterized in that.
[Claim 6]
　The pH of the acidic aqueous solution is 1 to 3,
　wherein the temperature of the acidic aqueous solution is at 40 ° C. or less,
　the contact time between the aqueous acid solution and the steel sheet having the galvanized layer is not more than 5 seconds
, wherein the method for manufacturing a galvanized steel sheet according to claim 4 or 5,.