JP4110750B2 - Organic coated steel sheet with excellent corrosion resistance and conductivity - Google Patents

Description

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【発明の効果】
以上述べたように本発明の有機被覆鋼板は、皮膜中に６価クロムを全く含まないにも拘らず、高度の導電性及び溶接性と耐食性とを兼ね備え、また高温多湿環境下での優れた耐黒点錆性を有している。
【図面の簡単な説明】
【図１】冷延鋼板の表面粗さに起因した局部的な薄膜部が形成された有機被覆鋼板の断面を模式的に示す説明図
【図２】調質圧延された冷延鋼板に亜鉛めっきを施し、その上層に下層皮膜と有機樹脂皮膜を順次形成した有機被覆鋼板であって、高温多湿環境促進試験において黒点錆が発生した有機被覆鋼板と黒点錆が発生しなかった有機被覆鋼板について、冷延鋼板表面の粗さの波長と平均表面粗さとの関係を示すグラフ
【図３】調質圧延をした冷延鋼板を素材鋼板とする有機被覆鋼板について、冷延鋼板表面の粗さの波長１００〜１５０μｍの山カウント数ＲＰＶＣ及び平均表面粗さＲａと有機被覆鋼板の黒点錆発生との関係を示すグラフ
【図４】調質圧延後の表面粗さが本発明条件を満足する冷延鋼板を亜鉛めっきし、その上層に無機系の下層皮膜を形成し、さらにその上層に熱硬化性エポキシ樹脂からなる有機樹脂皮膜を形成した有機被覆鋼板について、有機樹脂皮膜の付着量と耐食性（耐黒点錆性）との関係を示すグラフ
【図５】調質圧延後の表面粗さが本発明条件を満足する冷延鋼板を亜鉛めっきし、その上層に無機系の下層皮膜を形成し、さらにその上層に熱硬化性エポキシ樹脂からなる有機樹脂皮膜を形成した有機被覆鋼板について、有機樹脂皮膜の付着量と導電性との関係を示すグラフ
【図６】調質圧延後の表面粗さが本発明条件を満足する冷延鋼板を亜鉛めっきし、その上層に無機系の下層皮膜を形成し、さらにその上層に熱硬化性エポキシ樹脂からなる有機樹脂皮膜を形成した有機被覆鋼板について、有機樹脂皮膜の付着量と溶接性との関係を示すグラフ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic coated steel sheet suitable for home appliances, building materials, automobile applications, and the like, which does not contain hexavalent chromium in the film and has excellent corrosion resistance and conductivity.
[0002]
[Prior art]
Conventionally, steel sheets for home appliances, steel sheets for building materials, steel sheets for automobiles, etc. have been used for the purpose of improving the corrosion resistance (white rust resistance, red rust resistance) on the surface of zinc-plated steel sheets or aluminum-plated steel sheets, Steel plates subjected to chromate treatment with a treatment liquid mainly composed of dichromic acid or salts thereof are widely used. This chromate treatment can impart excellent corrosion resistance to the steel sheet by forming an extremely thin film and can be processed at low cost, so the steel sheet surface requires high conductivity such as weldability and grounding. It is widely used as a surface treatment for steel sheets for applications such as home appliances, automobiles, and building materials. The excellent corrosion resistance of the chromate film is the function of blocking the corrosion factor by the dense film of trivalent chromium hydrated oxide (barrier property), and hexavalent chromium is reduced at the film defect part to repair the film defect part. This is due to the function (self-repair action).
[0003]
Chromate treatment uses hexavalent chromium, which is a pollution-controlling substance, but this hexavalent chromium is processed in a closed system in the treatment process and is completely reduced and recovered, so it is not released to nature. In addition, the treated steel plate is covered with an organic resin film so that the environment and the human body are not contaminated by hexavalent chromium contained in the chromate film. However, due to recent global environmental problems, there has been a debate in Europe to restrict the inclusion of hexavalent chromium in waste electrical and electronic equipment and scrap cars, and there is a growing trend to voluntarily reduce the use of hexavalent chromium. is there. As the needs for chromium-free chemical conversion steel sheets increase due to these environmental problems, surface-treated steel sheets with high corrosion resistance using organic composite coatings have been studied, and recently many treatment technologies that do not rely on chromate treatment have been proposed. Has been.
[0004]
[Problems to be solved by the invention]
In general, in order to ensure corrosion resistance with a chromium-free organic coated steel sheet, it is considered that the film thickness of the organic resin film is required to be at least about 3 μm. However, with such a film thickness, OA equipment, AV equipment, etc. There is a problem with grounding in the application. In OA equipment, spot welding is often performed in the assembly process of the chassis, and in order to ensure high productivity, a high level of continuous spotting in spot welding is required, but the film thickness of the organic resin film is 3 μm or more. In this case, it is difficult to obtain a high degree of continuous hitting.
As an organic coated steel sheet having a relatively thin organic resin film, a mixed aqueous solution of polyvalent metal primary phosphate and metal oxide sol is applied and dried on the surface of a galvanized steel sheet in JP-A 2000-129460. The adhesion amount obtained from 0.05 to 1 g / m ² An amorphous film having an adhesion amount of 0.5 to 2 g / m on the upper layer. ² An organic coated steel sheet having an organic film is shown.
[0005]
However, digitalization has progressed in OA equipment and AV equipment, and strict conductivity has been required for the surface-treated steel sheet from noise countermeasures. In the case of an organic coated steel sheet having a chromate film, an extremely thin film exhibits excellent corrosion resistance, so that it is possible to meet such severe electrical conductivity requirements. However, the organic coating disclosed in the above-mentioned JP 2000-129460 A In conventional chromium-free organic coated steel sheets such as steel sheets, the thinner the film, the easier the corrosion from the defective part of the film occurs, thereby causing a problem that the corrosion resistance is significantly reduced. In the case of an organic coated steel sheet having a chromate film, a high degree of corrosion resistance can be obtained because a self-repairing action by hexavalent chromium is obtained at the film defect part. This is because the self-repair action cannot be obtained. Therefore, the conventional chromium-free organic coated steel sheet does not satisfy both conductivity and corrosion resistance to a high degree.
[0006]
In the field of AV / OA equipment and home appliances, the adoption of chromium-free chemical conversion steel sheets is progressing, and the production base has been moved to Southeast Asia to reduce manufacturing costs. For this reason, demand for galvanized steel sheets is also growing in Southeast Asia. Exports from domestic blast furnace manufacturers to Southeast Asia have increased rapidly, and hot rolled steel sheets used as raw materials have been exported from Japan. Local procurement such as manufacturing of
[0007]
However, in the hot and humid areas such as Southeast Asia, especially South China, the rainy season accounts for 80% of the year, which is a corrosive environment different from that in Japan. In such areas, the phenomenon that zinc corrodes locally (black spot rust) occurs during the period during which the surface-treated steel sheet is transported and stored, and there is a problem that impairs the commercial value of the surface-treated steel sheet. Was newly found. That is, it became clear that if the organic coated steel sheet developed for the domestic market is directly exported to Southeast Asia or produced locally, the occurrence of sunspot rust cannot be prevented.
Accordingly, an object of the present invention is to provide a chromium-free organic-coated steel sheet that has high conductivity and corrosion resistance, which are generally contradictory performances in organic-coated steel sheets, and is excellent in black spot rust resistance in a high-temperature and high-humidity environment. There is.
[0008]
[Means for Solving the Problems]
In order to ensure a high degree of conductivity, the inventors have set the film thickness of the organic resin film to 0.5 g / m. ² I found out that it was necessary to make it less than in my own study. On the other hand, for organic coated steel sheets with excellent corrosion resistance (white rust resistance, black spot rust resistance under high temperature and high humidity environment) without containing hexavalent chromium which has a self-repairing action in such an extremely thin film. The present inventors have studied from the viewpoint of how to suppress the occurrence of coating defects that are the starting point of corrosion, and how to suppress the unavoidable corrosion from the coating defects. As a result, using a cold-rolled steel sheet with a surface roughness after temper rolling controlled to a specific range as a raw steel sheet under a specific film configuration, it is possible to effectively generate film defects and associated corrosion. It has been found that the addition of a specific self-repairing substance in place of hexavalent chromium is particularly effective for the suppression of corrosion caused by unavoidable film defects.
[0009]
The present invention has been made based on such findings, and the features thereof are as follows.
[1] The surface of a temper-rolled cold-rolled steel sheet has a zinc-based plating film or an aluminum-based plating film, and the surface of the plating film contains 0.05 g / m of an organic resin film not containing hexavalent chromium. ² Or more, 0.5 g / m ² An organic coated steel sheet formed with an adhesion amount of less than
Crest count number RPVC with a wavelength of 100 to 150 μm of the roughness of the surface of the cold rolled steel sheet transferred by a temper rolling roll is 200 peak / inch or less, and the average surface roughness Ra is 1.5 μm or less. An organic coated steel sheet excellent in corrosion resistance and conductivity.
[0010]
[2] The surface of the temper-rolled cold-rolled steel sheet has a zinc-based plating film or an aluminum-based plating film, and the surface of the plating film is an inorganic, organic or inorganic-organic system that does not contain hexavalent chromium. Lower layer film 0.01-1000 mg / m ² An organic resin film that does not contain hexavalent chromium in the upper layer of the lower film is 0.05 g / m. ² Or more, 0.5 g / m ² An organic coated steel sheet formed with an adhesion amount of less than
Crest count number RPVC with a wavelength of 100 to 150 μm of the roughness of the surface of the cold rolled steel sheet transferred by a temper rolling roll is 200 peak / inch or less, and the average surface roughness Ra is 1.5 μm or less. An organic coated steel sheet excellent in corrosion resistance and conductivity.
[0011]
[3] The organic coated steel sheet having excellent corrosion resistance and conductivity, wherein the lower layer film is a film containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles in the organic coated steel sheet of [2] .
[4] In the organic coated steel sheet of the above [2], the lower layer film is phosphoric acid and / or a phosphoric acid compound, oxide fine particles, and one or more metals selected from Mn, Al, Mg, Ni (provided that An organic-coated steel sheet excellent in corrosion resistance and conductivity, characterized in that it is a film containing a compound and / or a compound compound).
[0012]
[5] In the organic-coated steel sheet according to any one of [1] to [4] above, the peak count number RPVC with a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by a roll of temper rolling is 100 peak / An organic coated steel sheet excellent in corrosion resistance and conductivity, characterized in that it is not more than inch.
[6] The organic coated steel sheet according to any one of [1] to [5] above, wherein the average surface roughness Ra of the cold rolled steel sheet transferred by a roll of temper rolling is 1.1 μm or less. Organic coated steel sheet with excellent corrosion resistance and conductivity.
[7] An organic coated steel sheet excellent in corrosion resistance and conductivity, characterized in that the organic resin film contains an antirust additive in the organic coated steel sheet of any one of [1] to [6].
[0013]
[8] In the organic coated steel sheet of [7], the rust preventive additive is at least one selected from the following (a1), (a2), (a3), (b), and (c) An organic coated steel sheet with excellent corrosion resistance and conductivity.
(a1) Calcium and / or calcium compound
(a2) Phosphate
(a3) Silicon oxide
(b) Molybdate
(c) one or more organic compounds selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
[0014]
[9] In the organic coated steel sheet of [7], the corrosion resistance and conductivity are characterized in that the rust preventive additive is one or more selected from the following (a), (b), and (c) Excellent organic coated steel sheet.
(a) Calcium and / or calcium compound and phosphate and / or silicon oxide
(b) Molybdate
(c) one or more organic compounds selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
[0015]
[10] An organic coated steel sheet having excellent corrosion resistance and conductivity, wherein the organic resin film contains a solid lubricant in the organic coated steel sheet of any one of [1] to [9].
[11] In the organic coated steel sheet according to any one of [1] to [10], the film-forming resin of the organic resin film is an active hydrogen-containing compound in which an epoxy group-containing resin and a part or all of the compound are hydrazine derivatives. An organic coated steel sheet excellent in corrosion resistance and conductivity, characterized by being a reaction product of
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention and the reasons for limitation will be described below.
The organic coated steel sheet of the present invention has a zinc-based plating film or an aluminum-based plating film on the surface of a temper-rolled cold-rolled steel sheet, and if necessary, a specific layer not containing hexavalent chromium in the upper layer of the plating film An organic coated steel sheet in which a lower coating (inorganic coating, organic coating, or inorganic-organic coating) having an adhesion amount is formed, and an organic resin coating having a specific adhesion amount not containing hexavalent chromium is formed thereon. The temper rolled cold-rolled steel sheet, which is a raw steel sheet, has a predetermined surface roughness.
[0017]
Hereinafter, the surface roughness of the temper rolled cold-rolled steel sheet, which is a raw steel sheet, will be described.
The present inventors have investigated the starting point on the surface of the organic coated steel plate where corrosion such as white rust and black spot rust occurs, and as a result, the organic coated steel plate has a locally thin portion of the organic resin film, This part was found to be the starting point of white rust and black spot rust. When an organic resin film having a very thin film thickness is formed on the steel sheet, a local thin film portion due to the roughness of the steel sheet surface is formed on the organic resin film. This is schematically shown in FIG. 1, and it has been found that such a local thin film portion is a starting point of corrosion.
[0018]
Furthermore, as a result of studying the steel sheet surface roughness affecting the formation of the thin film portion of the organic resin film as described above, the factors that cause such surface roughness, and the countermeasures thereof, there was a local thin film portion in the organic resin film. The surface roughness of the steel sheet as formed is caused by being transferred from the rolling roll during the temper rolling of the cold-rolled steel sheet, and thus the surface roughness transferred from the temper rolling roll is within a specific range. It has been found that the formation of local thin film portions can be suppressed by effectively restricting the formation of black spot rust and the like.
[0019]
An organic coated steel sheet in which a temper-rolled cold-rolled steel sheet is galvanized and a lower layer film and an organic resin film are sequentially formed on its upper layer. For the organic coated steel sheet where rust did not occur, after removing the organic resin film, lower layer film and galvanizing with acid, the roughness wavelength of the surface of the cold rolled steel sheet was measured with a non-contact type roughness meter. The result of arranging the relationship between the wavelength of the surface roughness and the average surface roughness Ra is shown in FIG. According to this, the organic coated steel sheet in which sunspot rust has occurred is extremely rough in the wavelength range of 100 to 150 μm compared to the organic coated steel sheet in which sunspot rust has not occurred, and this particular wavelength is exactly It was found that the temper rolling roll (in this case, the temper rolling roll having a discharge dull finish) coincides with the wavelength of the roughness of the roll surface. Therefore, it was found that the occurrence of black spot rust can be suppressed by controlling the surface roughness of the steel sheet after temper rolling, that is, by controlling the temper rolling conditions (surface roughness of the temper rolling roll, pressure regulation rate). .
[0020]
FIG. 3 shows the surface of a cold-rolled steel sheet by conducting a high-temperature and high-humidity environment promotion test shown in the examples to be described later for an organic-coated steel sheet made of a cold-rolled steel sheet that has been temper-rolled by the above-mentioned rolls of electric discharge dull finish The result of investigating the relationship between the peak count RPVC and the average surface roughness Ra of 100 nm to 150 μm of the roughness of the surface and the occurrence of sunspot rust on the organic coated steel sheet is shown. In addition, the evaluation of ◎ to × in the figure is the same as the evaluation of “(1) Corrosion resistance (black spot rust resistance)” in Examples described later. According to FIG. 3, the organic coated steel sheet in which sunspot rust is generated has a peak count RPVC of the specific wavelength of the roughness of the surface of the cold-rolled steel sheet transferred from the temper rolling roll, more than 200 peak / inch, average surface The roughness Ra is distributed in the region exceeding 1.5 μm, and the peak count RPVC of the above-mentioned specific wavelength of the roughness of the cold rolled steel sheet surface is controlled to 200 peak / inch or less and the average surface roughness Ra ≦ 1.5 μm. It can be seen that black spot rust can be effectively suppressed by doing so. Of these, the range of average surface roughness Ra ≦ 1.1 μm, and the range of the peak count RPVC of the specific wavelength of 100 peak / inch or less are particularly excellent in black spot rust resistance. Therefore, both are satisfied. It can be seen that the best black spot rust resistance can be obtained.
[0021]
For the reasons described above, in the present invention, the roughness of the surface of the cold-rolled steel sheet, which is the material steel sheet of the organic-coated steel sheet, is counted as a peak of the roughness of the surface of the cold-rolled steel sheet transferred by a roll of temper rolling at a wavelength of 100 to 150 μm. The number RPVC is defined as 200 peak / inch or less and the average surface roughness Ra is defined as 1.5 μm or less. Moreover, as a more preferable range of the surface roughness of the cold-rolled steel sheet, the peak count number RPVC of the specific wavelength is 100 peak / inch or less, and the average surface roughness Ra is 1.1 μm or less. Therefore, the roughness of the temper-rolled cold rolled steel sheet surface is most preferably such that the peak count number RPVC of the specific wavelength is 100 peak / inch or less and the average surface roughness Ra is 1.1 μm or less.
[0022]
In addition to zinc plating (electrogalvanizing, hot dip galvanizing) and alloyed hot dip galvanizing, the zinc-based plating film formed on the surface of the cold-rolled steel sheet as described above includes Zn, Ni, Cr, Mn, and Co. , Fe, Al, Mg, etc., alloy plating composed of one or more elements. The Zn—Al alloy plating includes so-called Zn-5% Al alloy plating and Zn-55% Al alloy plating. Furthermore, zinc-based composite plating (for example, Zn-SiO) in which metal oxides, polymers, etc. are dispersed in the plating films mentioned above. ₂ Dispersion plating) and the like. Moreover, it is good also as multilayer plating which plated two or more layers of the same kind or different kind among the above plating.
[0023]
In addition, examples of the aluminum-based plating film include aluminum plating and Al—Si alloy plating.
Moreover, as a plated steel plate, the steel plate surface may be previously plated with thinning such as Ni and the above-described various plating may be performed thereon.
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a nonaqueous solvent), a melting method, and a vapor phase method can be adopted.
[0024]
In addition, when an organic resin film as described later is formed on the surface of the plating film, in order to prevent unevenness of the film as much as possible, alkali degreasing, solvent degreasing, surface conditioning treatment ( A treatment such as an alkaline surface conditioning treatment or an acidic surface conditioning treatment can be performed. In addition, for the purpose of preventing blackening (a kind of oxidation phenomenon of the plating surface) under the usage environment of the organic coated steel sheet, iron group metal ions (Ni ions, Co ions, Fe ions) are previously applied to the plating film surface as necessary. Surface conditioning treatment with an acidic or alkaline aqueous solution containing one or more of the above. In addition, when an electrogalvanized steel sheet is used as the base steel sheet, an iron group metal ion (one or more of Ni ions, Co ions, Fe ions) is added to the electroplating bath for the purpose of preventing blackening, and the plating film These metals can be contained in an amount of 1 ppm or more. In this case, there is no particular limitation on the upper limit of the iron group metal concentration in the plating film.
[0025]
If necessary, a lower layer film not containing hexavalent chromium is formed on the surface of the plating film, and an organic resin film is formed on the upper layer (the surface of the plating film when the lower layer film is not formed).
The lower layer film may be any of an inorganic film, an organic film, and an inorganic-organic film as long as it does not contain hexavalent chromium. For example, crystalline zinc phosphate treatment film (inorganic), film containing amorphous phosphate (inorganic), alkali silicate film (inorganic), film containing polyhydric phenol compounds such as tannic acid (organic) Type), a known film such as a trivalent chromium-based chromate film (inorganic), an organic resin-containing trivalent chromium-based chromate film (inorganic-organic), and a film obtained by appropriately blending an organic resin with these films. .
[0026]
For the purpose of further improving the corrosion resistance, the lower layer film is a complex oxide film containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles, more preferably phosphoric acid and / or a phosphoric acid compound and an oxide. A composite oxide film containing fine particles and one or more metals selected from Mn, Al, Mg, and Ni (including a case where they are included as a compound and / or a composite compound) is preferable.
[0027]
As the oxide fine particles, silicon oxide (SiO2) is particularly preferable from the viewpoint of corrosion resistance. ₂ Fine particles) are preferred. Of the silicon oxides, colloidal silica is most preferable. Examples of colloidal silica include Snowtex O, Snowtex OS, Snowtex OXS, Snowtex OUP, Snowtex AK, Snowtex O40, Snowtex OL, Snowtex OL40, Snowtex OZL, Snowtex XS, Snowtex S , SNOWTEX NXS, SNOWTEX NS, SNOWTEX N, SNOWTEX QAS-25 (all trade names, manufactured by Nissan Chemical Industries, Ltd.), Cataloid S, Cataloid SI-350, Cataloid SI-40, Cataloid SA, Cataloid SN (Above product name, manufactured by Catalyst Kasei Kogyo Co., Ltd.), Adelite AT-20-50, Adelite AT-20N, Adelite AT-300, Adelite AT-300S, Adelite AT20Q (Abbreviated product name, Asahi Denka Kogyo Co., Ltd.) ), Or the like can be used.
[0028]
Among these silicon oxides, those having a particle diameter of 14 nm or less, more preferably 8 nm or less are desirable from the viewpoint of corrosion resistance.
In addition, as the silicon oxide, those obtained by dispersing dry silica fine particles in a coating composition solution can also be used. As this dry silica, for example, Aerosil 200, Aerosil 3000, Aerosil 300CF, Aerosil 380 (above, trade name, manufactured by Nippon Aerosil Co., Ltd.) and the like can be used. Is desirable.
As oxide fine particles, in addition to the above silicon oxide, colloidal solutions such as aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, and antimony oxide, fine powder, and the like can also be used.
[0029]
As for the phosphoric acid and / or the phosphoric acid compound, for example, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid or the like, or one or more of these metal salts and compounds are added to the coating composition. Therefore, it can mix | blend as a film | membrane component. Moreover, you may add 1 or more types of organic phosphoric acid and those salts (for example, phytic acid, phytate, phosphonic acid, phosphonate, and these metal salts) to a film | membrane composition. Of these, the primary phosphate is preferred from the viewpoint of the stability of the coating composition solution.
The presence form of phosphoric acid and phosphoric acid compound in the film is not particularly limited, and it may be crystalline or non-crystalline. There are no particular restrictions on the ionicity and solubility of phosphoric acid and phosphoric acid compounds in the film.
[0030]
The form in which one or more kinds of metals selected from Mn, Al, Mg, and Ni are present in the film is not particularly limited, and may be a metal or an oxide, hydroxide, hydrated oxide, or phosphate compound. Or a compound such as a coordination compound or a complex compound. The ionicity, solubility, etc. of these compounds, hydroxides, hydrated oxides, phosphate compounds, coordination compounds, etc. are not particularly limited.
As a method for introducing the metal into the film, it may be added to the film composition as a phosphate, sulfate, nitrate, chloride or the like of Mn, Al, Mg, Ni.
[0031]
(A) oxide fine particles and (c) one or more metals selected from Mn, Al, Mg, and Ni (provided that they are included as a compound and / or a composite compound) The molar ratio (including cases) (a) / (c) (where component (c) is the metal equivalent of the metal) is 0.1 to 20, and preferably 0.1 to 10. If this molar ratio (A) / (C) is less than 0.1, the effect of adding oxide fine particles cannot be sufficiently obtained. On the other hand, if it exceeds 20, the oxide fine particles may inhibit densification of the film.
[0032]
Further, (b) phosphoric acid and / or a phosphoric acid compound, and (c) one or more metals selected from Mn, Al, Mg, and Ni (provided that the compound and / Or molar ratio (including the case where it is included as a complex compound) (c) / (b) (however, component (b) is P ₂ O ₅ In terms of conversion and component (c), the metal amount of the metal is preferably 0.1 to 1.5. If this molar ratio is less than 0.1, the poor solubility of the composite oxide film is impaired by soluble phosphoric acid, and the corrosion resistance may be lowered. On the other hand, when the molar ratio exceeds 1.5, the stability of the processing solution is remarkably lowered.
[0033]
An organic resin can be further blended in the composite oxide film for the purpose of improving the workability and corrosion resistance of the film. As the organic resin, one or more of epoxy resin, urethane resin, acrylic resin, acrylic-ethylene copolymer, acrylic-styrene copolymer, alkyd resin, polyester resin, ethylene resin, and the like can be used. These can be introduced into the film as a water-soluble resin and / or a water-dispersible resin.
In addition to these water-based resins, it is effective to use a water-soluble epoxy resin, a water-soluble phenol resin, a water-soluble butadiene rubber (SBR, NBR, MBR), a melamine resin, a blocked isocyanate, an oxazoline compound, etc. as a crosslinking agent. It is.
[0034]
In the composite oxide film, as an additive for further improving the corrosion resistance, polyphosphate, phosphate (for example, zinc phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.), molybdic acid Salts, phosphomolybdates (eg, aluminum phosphomolybdate), organophosphoric acids and salts thereof (eg, phytic acid, phytate, phosphonic acid, phosphonate and their metal salts, alkali metal salts, etc.), One or more organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.), organic compounds (eg, polyethylene glycol, etc.) and the like may be blended.
[0035]
Furthermore, as other additives, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.), inorganic Pigment (for example, titanium oxide), chelating agent (for example, thiol), conductive pigment (for example, metal powder such as zinc, aluminum, nickel, iron phosphide, antimony dove type tin oxide), coupling agent ( For example, one or more of silane coupling agent, titanium coupling agent, etc.) and melamine / cyanuric acid adduct can be added.
[0036]
Although the anticorrosion mechanism of the composite oxide film as described above is not necessarily clear, (1) a dense and hardly soluble composite oxide film blocks a corrosion factor as a barrier film, and (2) silicon oxide or the like. Oxide fine particles form a stable and dense barrier film together with phosphoric acid and / or a phosphoric acid compound and one or more metals selected from Mn, Al, Mg and Ni; and (3) oxide fine particles In the case of silicon oxide, it is considered that excellent anticorrosion performance can be obtained by silicate ions promoting formation of basic zinc chloride in a corrosive environment and improving barrier properties.
The adhesion amount of the lower layer film is 0.01 to 1000 mg / m ² , Preferably 1 to 600 mg / m ² More preferably 10 to 500 mg / m ² And The amount of lower layer coating is 0.01 mg / m ² Less than 1, the corrosion resistance is insufficient, while the adhesion amount is 1000 mg / m. ² If it exceeds, the conductivity and weldability will deteriorate.
[0037]
Next, the organic resin film formed on the surface of the lower layer film or the plating film will be described.
The organic resin film has an adhesion amount of 0.05 g / m from the viewpoint of corrosion resistance. ² Or more, preferably 0.1 g / m ² That's it. Adhering amount is 0.05g / m ² If it is less than this, sufficient corrosion resistance cannot be obtained. Moreover, the upper limit of the adhesion amount is 0.5 g / m from the viewpoint of conductivity and weldability. ² Less than. In the present invention, the range of the adhesion amount of the organic resin film is an indispensable condition for ensuring a good balance between corrosion resistance, conductivity and weldability.
[0038]
A cold-rolled steel sheet whose surface roughness after temper rolling satisfies the conditions of the present invention is galvanized, and an inorganic coating containing a phosphoric acid compound and silica on its surface is 300 mg / m. ² The result of investigating the relationship between the adhesion amount of the organic resin film and the corrosion resistance (black spot rust resistance) of the organic coated steel sheet formed with an organic resin film made of a thermosetting epoxy resin on the upper layer was formed. FIG. 4 shows the result of examining the relationship between the adhesion amount of the organic resin film and the conductivity (surface resistance value), and FIG. 5 shows the result of examining the relationship between the adhesion amount of the organic resin film and the spot weldability. Each is shown in FIG. The test methods and evaluation criteria for corrosion resistance, conductivity and weldability in FIGS. 4 to 6 are “(1) Corrosion resistance (black spot rust resistance)”, “(2) Weldability” and “ (3) Same as “Conductivity”.
[0039]
According to FIG. 4, as the amount of the organic resin film adhered increases, the corrosion resistance under a high temperature and humidity environment is improved, and the amount of adhesion is 0.05 g / m. ² Or more, preferably 0.1 g / m ² By setting it as the above, the outstanding corrosion resistance (black spot rust resistance) is obtained. On the other hand, according to FIG. 5, the adhesion amount of the organic resin film is 0.5 g / m. ² It can be seen that the surface resistance value increases abruptly when the above is reached. Moreover, according to FIG. 6, the adhesion amount of the organic resin film is 0.5 g / m. ² When it becomes above, it turns out that spot weldability (spot continuous spotting property) falls rapidly. In general, it is known that as the amount of organic resin coating increases, the conductivity and spot weldability deteriorate. However, regarding the conductivity and spot weldability under extremely severe conditions such as this test condition, the organic resin coating Of 0.5g / m ² The characteristic changes greatly at the boundary, the adhesion amount 0.5g / m ² There has been no example reported so far that excellent conductivity and spot weldability can be obtained. For the above reasons, in the present invention, the adhesion amount of the organic resin film is 0.05 g / m. ² Or more, 0.5 g / m ² Less, preferably 0.1 g / m ² Or more, 0.5 g / m ² Less than.
[0040]
The film forming resin of the organic resin film is not particularly limited, and a thermosetting resin, a thermoplastic resin, or the like can be used. Any of water-soluble resins, water-dispersible resins, and organic solvent-soluble resins may be used. An organic composite silicate in which an organic resin is combined with silica through a silane coupling agent is also suitable. However, the adhesion amount is 0.5 g / m ² In order to provide high corrosion resistance with an extremely thin film thickness of less than, it is particularly preferable to use a thermosetting resin as the film-forming resin. The thermosetting resin has a three-dimensional network structure with a cross-linked structure, so it suppresses the permeation of oxygen, which is a corrosion factor (that is, has excellent oxygen barrier properties), and has an excellent effect on suppressing the cathode reaction. Demonstrate.
[0041]
As the film-forming resin for the organic resin film, for example, the following can be used.
(1) Epoxy resin
For example, epichlorohydrin type, glycidyl ether type straight epoxy resin, fatty acid modified epoxy resin (epoxy ester resin), polybasic acid modified epoxy resin, acrylic resin modified epoxy resin, alkyd (or polyester) modified epoxy resin, acrylic resin modified Epoxy resins, alkyd (or polyester) -modified epoxy resins, polybutadiene-modified epoxy resins, phenol-modified epoxy resins, amine or polyamine-modified epoxy resins, urethane-modified epoxy resins, and the like can be used. By using these epoxy resins or modified epoxy resins, excellent corrosion resistance and paintability can be imparted to the organic resin film.
[0042]
(2) Urethane resin
For example, an oil-modified polyurethane resin, an alkyd polyurethane resin, a polyester polyurethane resin, a polyether urethane resin, a polycarbonate polyurethane resin, or the like can be used.
(3) Alkyd resin
For example, oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin, styrenated alkyd resin, silicon-modified alkyd resin, acrylic-modified alkyd resin, oil-free alkyd resin, high molecular weight oil-free alkyd resin, and the like can be used.
[0043]
(4) Acrylic silicon resin
For example, an acrylic copolymer containing a hydrolyzable alkoxysilyl group in the side chain or terminal and having a curing agent added thereto can be used. When these acrylic silicon resins are used, excellent weather resistance of the organic resin film can be expected.
(5) Fluororesin
There are those of fluoroolefin copolymers, such as alkyl vinyl ether, synchroalkyl vinyl ether, carboxylic acid modified vinyl ester, hydroxyalkyl allyl ether, tetrafluoropropyl vinyl ether, etc. as monomers, and fluorine monomer (fluoroolefin) Copolymers or the like can be used. When these fluororesins are used, excellent weather resistance and excellent hydrophobicity of the organic resin film can be expected.
[0044]
(6) Acrylic resin
For example, polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer, polymethacrylic acid ester and its copolymer, polymethacrylic acid ester and its copolymer, urethane-acrylic acid copolymer (or Urethane-modified acrylic resin), styrene-acrylic acid copolymer, and the like, and resins obtained by modifying these resins with other alkyd resins, epoxy resins, phenol resins, and the like can also be used.
[0045]
(7) Ethylene resin (polyolefin resin)
For example, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene copolymer such as a carboxyl-modified polyolefin resin, an ethylene-unsaturated carboxylic acid copolymer, an ethylene ionomer, and the like can be used. Furthermore, resins obtained by modifying these resins with other alkyd resins, epoxy resins, phenol resins or the like can also be used.
[0046]
Also, when using a water dispersible resin, a core / shell type in which the core part and the shell part of the resin particle are made of different types of resins or resins having different glass transition temperatures for the purpose of lowering the drying temperature of the resin. A water dispersible resin can be used. In addition, a water-dispersible resin having self-crosslinkability, for example, a water-dispersible resin in which an alkoxysilane group is added to the resin particle can be used. By using such a water-dispersible resin, the resin can be heated and dried. Generation of silanol groups by hydrolysis of alkoxysilane and crosslinking between resin particles by dehydration condensation reaction of silanol groups between resin particles can be used.
[0047]
In the present invention, when particularly excellent corrosion resistance and workability are imparted to the organic resin film, it is desirable to use a thermosetting resin as the film forming resin. In this thermosetting resin, urea resin (butylated urea resin, etc.), melamine resin (butylated melamine resin), butylated urea / melamine resin, amino resin such as benzoguanamine resin, blocked isocyanate, An oxazoline compound, a phenol resin, etc. can be mix | blended.
[0048]
Among the film-forming resins listed above, epoxy resins and ethylene-based resins are preferred from the viewpoint of the corrosion resistance, workability, and paintability of organic films, and in particular, excellent barrier properties against corrosion factors such as oxygen. A thermosetting epoxy resin or a modified epoxy resin having the above is suitable. For example, a thermosetting epoxy resin, a thermosetting modified epoxy resin, an acrylic copolymer resin copolymerized with an epoxy group-containing monomer, a polybutadiene resin having an epoxy group, a polyurethane resin having an epoxy group, and addition of these resins These epoxy group-containing resins can be used alone or in admixture of two or more.
[0049]
Among these epoxy group-containing resins, an epoxy group-containing resin modified with a hydrazine derivative, that is, an active hydrogen in which an epoxy group-containing resin such as the above-described epoxy resin or modified epoxy resin and a part or all of the compound is a hydrazine derivative. Particularly preferred are reaction products with contained compounds.
Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy group-containing resin include those shown below, and one or more of these compounds can be used. Some (preferably all) need to be hydrazine derivatives having active hydrogen.
・ Hydrazine derivatives with active hydrogen
.Primary or secondary amine compounds having active hydrogen
・ Organic acids such as ammonia and carboxylic acids
・ Hydrogen halides such as hydrogen chloride
・ Alcohols and thiols
· A quaternary chlorinating agent which is a mixture of a hydrazine derivative or a tertiary amine and an acid having no active hydrogen
[0050]
Examples of the hydrazine derivative having active hydrogen include the following.
(1) Carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenone hydrazone Hydrazide compounds such as
(2) Pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;
[0051]
(3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;
[0052]
(4) tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) Thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
(6) Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone, etc. Pyridazine compounds
Of these, pyrazole compounds and triazole compounds having a 5-membered or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.
These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.
[0053]
Typical examples of the amine compound having active hydrogen that can be used as a part of the active hydrogen-containing compound include the following.
(1) A primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, A compound modified with aldimine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of about 100 to 230 ° C., for example;
[0054]
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(3) Secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and dialkyl (meth) acrylamide by Michael addition reaction;
(4) A compound obtained by modifying the primary amino group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '(aminopropoxy) ethyl ether to ketimine;
[0055]
The quaternary chlorinating agent that can be used as a part of the active hydrogen-containing compound can react with an epoxy group because a hydrazine derivative or a tertiary amine that does not have an active hydrogen is not reactive with an epoxy group by itself. Therefore, it is a mixture with an acid. A quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with an epoxy group-containing resin.
The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid. Examples of the hydrazine derivative having no active hydrogen used to obtain a quaternary chlorinating agent include 3,6-dichloropyridazine and the like, and examples of the tertiary amine include dimethylethanolamine, triethylamine, Examples include trimethylamine, triisopropylamine, and methyldiethanolamine.
[0056]
The reaction product of an epoxy group-containing resin and an active hydrogen-containing compound comprising a hydrazine derivative in which some or all of the compounds have active hydrogen is obtained by reacting the epoxy group-containing resin and the active hydrogen-containing compound at 10 to 300 ° C., preferably 50 It is obtained by reacting at ~ 150 ° C for about 1 to 8 hours.
This reaction may be performed by adding an organic solvent, and the type of the organic solvent to be used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether , Propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other alcohols and ethers containing a hydroxyl group; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons such as It can be used one or two or more thereof. Of these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, film-forming properties, and the like.
[0057]
The compounding ratio of the epoxy group-containing resin and the active hydrogen-containing compound comprising a hydrazine derivative in which some or all of the compounds have active hydrogen is an active hydrogen-containing compound with respect to 100 parts by weight of the epoxy group-containing resin as a solid content 0.5 to 20 parts by weight, particularly preferably 1.0 to 10 parts by weight.
The blending ratio of the epoxy group-containing resin and the active hydrogen-containing compound is such that the ratio of the number of active hydrogen groups in the active hydrogen-containing compound to the number of epoxy groups in the epoxy group-containing resin [number of active hydrogen groups / epoxy groups] is 0. It is appropriate from the viewpoint of corrosion resistance and the like to be 0.01 to 10, more preferably 0.1 to 8, and still more preferably 0.2 to 4.
[0058]
The proportion of the hydrazine derivative having active hydrogen in the active hydrogen-containing compound is suitably 10 to 100 mol%, more preferably 30 to 100 mol%, and still more preferably 40 to 100 mol%. If the ratio of the hydrazine derivative having active hydrogen is less than 10 mol%, the organic film cannot be provided with a sufficient rust prevention function, and the resulting rust prevention effect is obtained by simply mixing the film-forming organic resin and the hydrazine derivative. There will be no big difference from the case.
[0059]
Although the anticorrosion mechanism by the organic resin film composed of such a specific reaction product is not necessarily clear, the mechanism can be estimated as follows. That is, by applying a hydrazine derivative to the film-forming organic resin, (1) an effect of blocking corrosion factors such as oxygen and chlorine ions can be obtained by a dense organic polymer film, and (2) the hydrazine derivative is an underlayer film. (3) To form a stable insoluble chelate compound layer by trapping zinc ions eluted by the corrosion reaction with free hydrazine derivatives in the coating. It is considered that the formation of the ion conductive layer at the interface is suppressed and the progress of the corrosion is suppressed, and the progress of the corrosion is effectively suppressed by the action effects such as excellent corrosion resistance.
[0060]
In particular, when an epoxy group-containing resin is used as the film-forming organic resin, a dense barrier film is formed by the reaction between the epoxy group-containing resin and the crosslinking agent, and this barrier film suppresses the permeation of corrosion factors such as oxygen. It is considered that excellent corrosion resistance can be obtained because of its excellent performance and excellent bonding strength with the substrate due to the hydroxyl groups in the molecule.
Furthermore, by using a pyrazole compound having active hydrogen and / or a triazole compound having active hydrogen as the hydrazine derivative having active hydrogen, more excellent corrosion resistance can be obtained.
[0061]
A rust preventive additive and a solid lubricant can be added to the organic resin film as necessary.
The anti-rust additive added to the organic resin film includes the following (a1), (a2), (a3), (b), and (c), which are effective anti-rust additives. It is preferable to use 1 or more types selected from the above, and this can effectively improve the corrosion resistance of the film defects that inevitably occur.
(A1) Calcium and / or calcium compounds
(A2) Phosphate
(A3) Silicon oxide
(B) Molybdate
(C) one or more organic compounds selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
Moreover, about the anti-rust additive of said (a1)-(a3), combined addition with (a1) and (a2) and / or (a3) is especially desirable from a viewpoint of corrosion resistance improvement.
[0062]
The anticorrosion mechanism obtained by blending the anticorrosive additives (a1) to (a3), (b), and (c) in the organic resin film is as follows.
First, each of the rust preventive additives (a1) to (a3) exhibits self-repairability of a film defect portion by a precipitation action. In addition, the reaction mechanism when the above (a1) and (a2) or / and (a3) are added in combination is considered to proceed in the following steps.
[First step]: Under the corrosive environment, base calcium dissolves preferentially over zinc and aluminum which are plating metals.
[Second step]: When the phosphate added in (a2) is added to (a1) above, phosphate ions dissociated by hydrolysis and calcium preferentially dissolved in the first step Ions cause complexation reactions. In the case of silicon oxide (a3) added in combination with (a1) above, the calcium ions preferentially dissolved in the first step are adsorbed on the surface of the silicon oxide, and the surface charge is electrically removed. Neutralizes and aggregates. As a result, in each case, a dense and hardly soluble protective film is formed, which inhibits the corrosion reaction by blocking the corrosion starting point.
[0063]
The anticorrosive additive (b) exhibits self-repairing properties due to the passivating effect. That is, a dense oxide is formed on the surface of the plating film together with dissolved oxygen in a corrosive environment, and this inhibits the corrosion reaction by blocking the corrosion starting point.
Furthermore, the anticorrosive additive (c) exhibits self-repairing properties due to the adsorption effect. That is, zinc and aluminum eluted by corrosion are adsorbed to the polar group containing nitrogen and sulfur of the above (c) to form an inactive film, which inhibits the corrosion reaction by blocking the corrosion starting point.
[0064]
The calcium compound (a1) may be any of a salt, a hydroxide, and an oxide, and one or more of these calcium compounds and metallic calcium can be used. In addition, there are no particular restrictions on the type of calcium salt. In addition to simple salts containing only calcium as a cation such as calcium silicate, calcium carbonate, calcium phosphate, etc., calcium and calcium such as calcium phosphate / zinc, calcium phosphate / magnesium, etc. Double salts containing other cations may be used.
[0065]
The phosphate of the above (a2) includes all types of salts such as single salt and double salt. Moreover, there is no limitation in the metal cation which comprises it, Any metal cation, such as zinc phosphate, magnesium phosphate, calcium phosphate, aluminum phosphate, may be sufficient. Further, there is no limitation on the skeleton or the degree of condensation of phosphate ions, and any of normal salt, dihydrogen salt, monohydrogen salt or phosphite may be used. Includes all condensed phosphates such as acid salts.
[0066]
The silicon oxide (a3) may be colloidal silica or dry silica. Further, among silicon oxides, ion exchange silica in which metal ions such as calcium are bonded to the surface is particularly desirable. Ion exchange silica is obtained by fixing metal ions such as calcium ions on the surface of a porous silica gel powder, and releases metal ions in a corrosive environment to form a precipitated film. Of these ion exchange silicas, calcium ion exchange silica is most preferred. Examples of the calcium ion exchange silica include SHIELDEX C303, SHIELDEX AC3, SHIELDEX AC5 (above trade name, manufactured by WRGrace & Co.), SHIELDEX, SHIELDEX SY710 (above trade name, manufactured by Fuji Silysia Chemical Co., Ltd.), and the like.
[0067]
Further, particularly excellent corrosion resistance can be obtained by adding a combination of ion exchange silica (particularly preferably, calcium ion exchange silica) and fine particle silica. The fine particle silica may be either colloidal silica or fumed silica. When colloidal silica is based on an aqueous film-forming resin, for example, Snowtex O, Snowtex N, Snowtex 20, Snowtex 30, Snowtex 40, Snowtex C, Snowtex S (above trade names, Nissan Chemical Co., Ltd.) can be used, and when a solvent-based film forming resin is used as a base, for example, organosilica sol MA-ST-M, organosilica sol IPA-ST, organosilica sol EG-ST, organo Silica sol E-ST-ZL, organosilica sol NPC-ST, organosilica sol DMAC-ST, organosilica sol DMAC-ST-ZL, organosilica sol XBA-ST, organosilica sol MIBK-ST (above trade name, manufactured by Nissan Chemical Industries, Ltd.) ) Etc. can be used
[0068]
Moreover, as fumed silica, AEROSILR971, AEROSILR R812, AEROSILR R811, AEROSILR R974, AEROSILR R202, AEROSILR R805, AEROSILR 130, AEROSILR 200, AEROSILR 300, AEROSILR 300CF (above, manufactured by Nippon Aerosil Co., Ltd.) Can be used.
[0069]
These fine-particle silicas contribute to the production of dense and stable zinc corrosion products in a corrosive environment, and the corrosion products can be formed densely on the plating surface, thereby suppressing the promotion of corrosion. A particularly excellent anticorrosion effect can be obtained by combining such an anticorrosion mechanism with the above-described anticorrosion mechanism of ion-exchange silica. The compounding ratio (x) / (y) (mass ratio) of the ion exchange silica (x) and the fine particle silica (y) is 99/1 to 1/99, preferably 95/5 to 40/60, more preferably 90 /. It is suitable to set it as 10-60 / 40. In any case where the weight ratio (x) / (y) between the ion exchange silica (x) and the fine particle silica (y) is less than 1/99 or more than 99/1, the effect of the combined addition of the two cannot be sufficiently obtained.
[0070]
The molybdate (b) is not limited in its skeleton and degree of condensation, and examples thereof include orthomolybdate, paramolybdate, and metamolybdate. Moreover, all salts, such as a single salt and a double salt, are included, and a phosphate molybdate etc. are mentioned as a double salt.
Among the organic compounds of (c) above, as the triazoles, 1,2,4-triazole, 3-amino-1,2,4-triazole, 1H-benzotriazole, etc., and as the thiols, 1 , 3,5-triazine-2,4,6-trithiol, 2-mercaptobenzimidazole and the like, and as thiadiazoles, 5-amino-2-mercapto-1,3,4-thiadiazole, 2,5- Dimercapto-1,3,4-thiadiazole, etc., as thiazoles, 2-N, N diethylthiobenzothiazole, 2-mercaptobenzothiazoles, etc., and as thiurams, tetraethylthiuram disulfide, etc. , Respectively.
[0071]
The rust preventive additives (self-repairing substances) of (a1) to (a3), (b), and (c) described above are precipitated in a corrosive environment as described above (a1) to (a3). According to the effect, (b) forms a protective film due to the passivation effect, and (c) forms the protective film due to the adsorption effect.
As a compounding quantity of the antirust additive of said (a1)-(a3), (b), (c) in an organic resin membrane | film | coat, it is total with respect to 100 weight part (solid content) of the resin component in a membrane | film | coat. 1 to 100 parts by weight (solid content), preferably 5 to 80 parts by weight (solid content), more preferably 10 to 50 parts by weight (solid content). When the total blending amount of the rust preventive additives (a1) to (a3), (b) and (c) is less than 1 part by weight, the effect of improving the corrosion resistance is small. On the other hand, if the blending amount exceeds 100 parts by weight, both corrosion resistance and electrical conductivity are lowered, which is not preferable.
[0072]
In addition to the above rust preventive additives (self-repairing substances), other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, oxidation) Antimony, etc.), phosphomolybdate (eg, aluminum phosphomolybdate, etc.), organic phosphoric acid or a salt thereof (eg, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts, alkali metal salts thereof) , Alkaline earth metal salts, etc.), organic inhibitors (hydrazine derivatives, thiol compounds, dithiocarbamates, etc.) can be added.
[0073]
Further, for the purpose of improving the workability of the film, a solid lubricant can be blended in the organic resin film as necessary. Examples of the solid lubricant applicable to the present invention include the following, and one or more of these can be used.
(1) Polyolefin wax, paraffin wax: For example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc.
(2) Fluorine resin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.), polyvinyl fluoride resin, polyvinylidene fluoride resin, etc.
[0074]
In addition to these, fatty acid amide compounds (for example, stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, oleic acid amide, esylic acid amide, alkylene bis fatty acid amide, etc.), metal Soaps (for example, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal sulfides (molybdenum disulfide, tungsten disulfide, etc.), graphite, graphite fluoride, boron nitride, polyalkylene glycol, alkali metal One or more of sulfates may be used.
[0075]
Among the above solid lubricants, polyethylene wax and fluorine resin compounds (particularly polytetrafluoroethylene resin fine particles) are particularly suitable. As the polyethylene wax, celite dust 9615A, celite dust 3715, celite dust 3620, ceridust 3910 (above trade name, manufactured by Hoechst), sun wax 131-P, sun wax 161-P (above trade name, manufactured by Sanyo Chemical Co., Ltd.), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) and the like can be used.
[0076]
Further, as the fluororesin fine particles, tetrafluoroethylene fine particles are particularly optimal. For example, Lubron L-2, Lubron L-5 (above trade name, manufactured by Daikin Industries, Ltd.), MP1100, MP1200 (above trade names, (Mitsui / DuPont Co., Ltd.), Full-on dispersion AD1, Full-on dispersion AD2, Full-on L140J, Full-on L150J, Full-on L155J (trade name, manufactured by Asahi IC Fluoropolymers) are suitable.
Of these, a particularly excellent lubricating effect is obtained when a polyolefin wax and tetrafluoroethylene are used in combination.
[0077]
The blending amount of these solid lubricants is preferably 1 to 80 parts by weight with respect to 100 parts by weight (solid content) of the resin component in the film. When the blending amount of the solid lubricant is less than 1 part by weight, the lubricating effect is poor, and when it exceeds 80 parts by weight, the paintability is lowered. Moreover, a preferable compounding quantity is 3-40 weight part.
[0078]
Further, as necessary, other additives include organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes). Etc.), inorganic pigments (eg titanium oxide etc.), chelating agents (eg thiols etc.), conductive pigments (eg metal powders such as zinc, aluminum, nickel, iron phosphide, antimony doped tin oxide etc.), Coupling agents (for example, silane coupling agents, titanium coupling agents, etc.), melamine / cyanuric acid adducts, and the like can be added.
[0079]
In order to produce the organic coated steel sheet of the present invention, the surface of the cold-rolled steel sheet transferred by the roll of temper rolling is roughened by temper rolling of the cold-rolled steel sheet using a roll having an adjusted surface roughness. The peak count RPVC at a wavelength of 100 to 150 μm is 200 peak / inch or less, preferably 100 peak / inch or less, and the average roughness Ra is 1.5 μm or less, preferably 1.1 μm or less. Such cold-rolled steel sheet after temper rolling is subjected to zinc-based plating or aluminum-based plating, and a composition (solution) for the lower layer coating is applied to the surface of this zinc-based plated steel sheet or aluminum-based plated steel sheet as necessary. ) And dried by heating, and then a composition (solution) for the organic resin film is applied and dried by heating.
[0080]
When a lower layer film is formed, the composition (solution) is 0.01 to 1000 mg / m in terms of the amount of adhesion after drying. ² , Preferably 1 to 600 mg / m ² , More preferably 10 to 500 mg / m ² Apply to dry and dry.
The method of applying the composition (solution) for the lower layer coating to the surface of the zinc-based plated steel plate or the aluminum-based plated steel plate may be any of a coating method, a dipping method, and a spray method. Moreover, any coating means such as a roll coater (3-roll system, 2-roll system, etc.), a squeeze coater, a die coater, or the like may be used. In addition, after the coating process using the squeeze coater or the like, the dipping process or the spraying process, the coating amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by the air knife method or the roll drawing method. Usually, after application of the composition (solution), heat drying is performed without washing with water, but in some cases, washing with water may be performed after application.
[0081]
A method of heating and drying the applied composition (solution) is arbitrary, and means such as a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace, etc. can be used. The heat drying treatment is suitably performed in the range of 40 to 350 ° C., preferably 70 ° C. to 200 ° C., more preferably 70 ° C. to 160 ° C. at the ultimate plate temperature. If the heating and drying temperature is less than 40 ° C., a large amount of moisture remains in the film, so that the corrosion resistance tends to be insufficient. On the other hand, if it exceeds 350 ° C., not only is it uneconomical, but the film has cracks and the like, resulting in corrosion resistance. It tends to decrease.
[0082]
When forming an organic resin film, the composition (solution) is 0.05 g / m in terms of the amount of adhesion after drying. ² Or more, 0.5 g / m ² Less, preferably 0.1 g / m ² Or more, 0.5 g / m ² Apply and dry to heat to less than
The composition (solution) for the organic film comprises the above-mentioned film components and an organic solvent and / or water, and an appropriate amount of a neutralizing agent, a lubricity-imparting agent, an anticorrosive additive, etc., as necessary. It can be included.
[0083]
The method of applying the composition (solution) for the organic film to the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet or the upper layer of the lower layer film may be any of an application method, a dipping method, and a spray method. In the coating method, any coating means such as a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, a die coater, or the like may be used. In addition, after the coating process using the squeeze coater or the like, the dipping process or the spraying process, the coating amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by the air knife method or the roll drawing method. Usually, after application of the composition (solution), heat drying is performed without washing with water, but in some cases, washing with water may be performed after application.
[0084]
A method of heating and drying the applied composition (solution) is arbitrary, and means such as a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace, etc. can be used. It is appropriate that the heat drying treatment is carried out in the range of 50 to 350 ° C., preferably 60 to 250 ° C., at the ultimate plate temperature. If the heating and drying temperature is less than 50 ° C, a large amount of organic solvent and water remain in the film, and thus the corrosion resistance tends to be insufficient. On the other hand, if it exceeds 350 ° C, not only is it uneconomical, but the film has defects. Corrosion resistance tends to decrease.
[0085]
【Example】
A resin composition (reaction product) for forming an organic film was synthesized as follows.
[Synthesis Example 1]
EP828 (manufactured by Yuka Shell Epoxy Co., Epoxy Equivalent 187) 1870 parts, bisphenol A 912 parts, tetraethylammonium bromide 2 parts, methyl isobutyl ketone 300 parts are charged into a four-necked flask and heated to 140 ° C. and reacted for 4 hours. An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this product, 1500 parts of ethylene glycol monobutyl ether was added and cooled to 100 ° C., 96 parts of 3,5-dimethylpyrazole (molecular weight 96) and 129 parts of dibutylamine (molecular weight 129) were added, and the epoxy group disappeared. After reacting for 6 hours, 205 parts of methyl isobutyl ketone was added while cooling to obtain a pyrazole-modified epoxy resin having a solid content of 60%. This is designated as resin composition (1). This resin composition (1) is a reaction product of a film-forming organic resin (A) and an active hydrogen-containing compound containing 50 mol% of a hydrazine derivative (C) having active hydrogen.
[0086]
[Synthesis Example 2]
4000 parts of EP1007 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 2000) and 2239 parts of ethylene glycol monobutyl ether were charged into a four-necked flask and heated to 120 ° C. to completely dissolve the epoxy resin in 1 hour. This was cooled to 100 ° C., 168 parts of 3-amino-1,2,4-triazole (molecular weight 84) was added, and the mixture was allowed to react for 6 hours until the epoxy group disappeared. A triazole-modified epoxy resin having a solid content of 60% was obtained. This is designated as resin composition (2). This resin composition (2) is a reaction product of a film-forming organic resin (A) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (C) having active hydrogen.
[0087]
[Synthesis Example 3]
222 parts of isophorone diisocyanate (isocyanate equivalent 111) and 34 parts of methyl isobutyl ketone were charged into a four-necked flask and maintained at 30 to 40 ° C., and 87 parts of methyl ethyl ketoxime (molecular weight 87) was added dropwise over 3 hours. By maintaining the time, a partially blocked isocyanate having an isocyanate equivalent of 309 and a solid content of 90% was obtained.
[0088]
Subsequently, 1428 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 187), 684 parts of bisphenol A, 1 part of tetraethylammonium bromide and 241 parts of methyl isobutyl ketone were charged into a four-necked flask and heated to 140 ° C. for 4 hours. Reaction was performed to obtain an epoxy resin having an epoxy equivalent of 1090 and a solid content of 90%. To this, 1000 parts of methyl isobutyl ketone was added and then cooled to 100 ° C., and 202 parts of 3-mercapto-1,2,4-triazole (molecular weight 101) was added and reacted for 6 hours until the epoxy group disappeared. Thereafter, 230 parts of the partially blocked isocyanate having a solid content of 90% was added and reacted at 100 ° C. for 3 hours to confirm that the isocyanate group had disappeared. Further, 461 parts of ethylene glycol monobutyl ether was added to obtain a triazole-modified epoxy resin having a solid content of 60%. This is designated as resin composition (3). This resin composition (3) is a reaction product of a film-forming organic resin (A) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (C) having active hydrogen.
[0089]
[Synthesis Example 4]
EP828 (manufactured by Yuka Shell Epoxy Co., Epoxy Equivalent 187) 1870 parts, bisphenol A 912 parts, tetraethylammonium bromide 2 parts, methyl isobutyl ketone 300 parts are charged into a four-necked flask and heated to 140 ° C. and reacted for 4 hours. An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this was added 1500 parts of ethylene glycol monobutyl ether, cooled to 100 ° C., added with 258 parts of dibutylamine (molecular weight 129), reacted for 6 hours until the epoxy group disappeared, and then cooled with methyl isobutyl. 225 parts of ketone was added to obtain an epoxyamine adduct having a solid content of 60%. This is designated as resin composition (4). This resin composition (4) is a reaction product of a film-forming organic resin (A) and an active hydrogen-containing compound that does not contain a hydrazine derivative (C) having active hydrogen.
[0090]
Cold rolled steel sheets with different average roughness Ra and peak count RPVC with a wavelength of 100-150 μm of the roughness of the steel sheet surface transferred by temper rolling rolls as organic coated steel sheets for home appliances, building materials, and automobile parts Each of these was subjected to various zinc plating or aluminum plating shown in Table 1 and used as a processing original plate. In addition, the cold-rolled steel plate employ | adopted the thing of predetermined | prescribed board thickness according to the objective of evaluation.
After the surface of this plated steel sheet was subjected to alkali degreasing treatment, washed with water and dried, the composition (solution) for the lower layer film shown in Tables 2 and 3 was applied with a roll coater and then dried by heating. The adhesion amount of the lower layer film was adjusted by changing the solid content (heating residue) or coating conditions (rolling force, rotation speed, etc.) of the coating composition.
[0091]
Subsequently, the composition (solution) for organic resin film was apply | coated to the upper layer of the lower layer film with the roll coater, and it heat-dried. As a composition (solution) for an organic film, a rust preventive additive (self-repairing substance) shown in Table 6 and a solid lubricant shown in Table 7 are optionally added to the resin compositions shown in Tables 4 and 5. The compositions shown in Tables 8 and 9 obtained by blending and stirring and pulverizing this for a necessary time using a disperser for coating (sand grinder) were used. The adhesion amount of the organic resin film was adjusted by changing the solid content of the composition (heating residue) or coating conditions (roll rolling force, rotation speed, etc.).
[0092]
The organic coated steel sheet thus obtained was evaluated for corrosion resistance (black spot rust resistance) and conductivity by the following test method. In addition, the organic resin film, lower layer film and plating film of the organic coated steel sheet used for the test were removed by etching with an acid, and the roughness wavelength of the cold-rolled steel sheet surface was measured with a non-contact type roughness meter. A crest count RPVC of 100 to 150 μm and an average roughness Ra were measured. The results are shown in Tables 10 to 16 together with the film configuration of the organic coated steel sheet.
[0093]
(1) Corrosion resistance (rust resistance against black spots)
A test piece of 70 mm × 150 mm size was stored for a predetermined period (500 hours and 1000 hours) under high temperature and high humidity environment promotion test conditions (50 ° C. × 98 RH%), and the occurrence of black spot rust was investigated and evaluated according to the following criteria. The storage environment is indoors.
◎: No black spot rust
○ +: 1-2 sunspot rust
○: 3 to 5 black spot rust
○-: 6 to 10 sunspot rust
Δ: 11 to 50 sunspot rust
×: More than 50 sunspot rust
[0094]
(2) Spot weldability
Using a test piece with a plate thickness of 1.2 mm, an upper electrode CR type (original diameter 16 mm, tip diameter 5.4 mm), lower electrode F type (tip diameter 16 mm), pressurization pressure 300 kg, energization time 13 cycles (60 Hz) Under the conditions, a spot spot weldability continuous spot test was performed, and the case where the nugget diameter was smaller than 4.4 mm was regarded as the limit of the weld spot, and was evaluated as follows.
◎: More than 3000 consecutive hit points
○: Continuous hitting point 1000 points or more and less than 3000 points
Δ: Continuous hitting point of 500 points or more and less than 1000 points
×: Less than 500 consecutive hit points
[0095]
(3) Conductivity (surface resistance value)
Using a four-probe resistivity meter (“Loresta AP” manufactured by Mitsubishi Chemical Corporation), the surface resistance of the test piece was measured and evaluated as follows.
A: Surface resistance value 10 ^-4 Ω or less
○: Surface resistance value 10 ^-4 Over Ω, 10 ^-3 Ω or less
Δ: Surface resistance value 10 ^-3 Over Ω, 10 ² Ω or less
X: Surface resistance value 10 ² Over Ω
[0096]
[Table 1]

[0097]
[Table 2]

[0098]
[Table 3]

[0099]
[Table 4]

[0100]
[Table 5]

[0101]
[Table 6]

[0102]
[Table 7]

[0103]
[Table 8]

[0104]
[Table 9]

[0105]
[Table 10]

[0106]
[Table 11]

[0107]
[Table 12]

[0108]
[Table 13]

[0109]
[Table 14]

[0110]
[Table 15]

[0111]
[Table 16]

[0112]
【The invention's effect】
As described above, the organic-coated steel sheet of the present invention has high conductivity, weldability and corrosion resistance in spite of having no hexavalent chromium in the film, and is excellent in a high-temperature and high-humidity environment. Has black spot rust resistance.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing a cross section of an organic coated steel sheet in which a local thin film portion is formed due to the surface roughness of a cold rolled steel sheet.
FIG. 2 is an organic coated steel sheet in which a temper-rolled cold-rolled steel sheet is galvanized and a lower layer film and an organic resin film are sequentially formed on the galvanized steel sheet. A graph showing the relationship between the surface roughness of the cold-rolled steel sheet and the average surface roughness of the coated steel sheet and the organic-coated steel sheet where no sunspot rust occurred.
FIG. 3 shows an organic coated steel sheet made of a temper-rolled cold-rolled steel sheet as a raw steel sheet, a cold-rolled steel sheet surface roughness wavelength RPVC of 100 to 150 μm, an average surface roughness Ra, and an organic coated steel sheet Graph showing the relationship with the occurrence of sunspot rust
FIG. 4 shows a galvanized cold rolled steel sheet whose surface roughness after temper rolling satisfies the conditions of the present invention, forms an inorganic lower layer film on the upper layer, and further comprises a thermosetting epoxy resin on the upper layer. A graph showing the relationship between the amount of organic resin film deposited and corrosion resistance (black spot rust resistance) for organic coated steel sheets with an organic resin film formed
FIG. 5: A galvanized cold rolled steel sheet whose surface roughness after temper rolling satisfies the conditions of the present invention, forms an inorganic lower layer film on the upper layer, and further comprises a thermosetting epoxy resin on the upper layer A graph showing the relationship between the amount of organic resin film deposited and the conductivity of an organic coated steel sheet with an organic resin film
FIG. 6 shows a galvanized cold-rolled steel sheet whose surface roughness after temper rolling satisfies the conditions of the present invention, forms an inorganic lower layer film on the upper layer, and further comprises a thermosetting epoxy resin on the upper layer. Graph showing the relationship between the amount of organic resin film deposited and weldability for organic coated steel sheets with an organic resin film formed

Claims (11)

The surface of the temper-rolled cold-rolled steel sheet has a zinc-based plating film or an aluminum-based plating film, and an organic resin film not containing hexavalent chromium is 0.05 g / m ² or more on the surface of the plating film. An organic coated steel sheet formed with an adhesion amount of less than 5 g / m ² ,
Crest count number RPVC with a wavelength of 100 to 150 μm of the roughness of the surface of the cold rolled steel sheet transferred by a temper rolling roll is 200 peak / inch or less, and the average surface roughness Ra is 1.5 μm or less. An organic coated steel sheet excellent in corrosion resistance and conductivity. An inorganic, organic or inorganic-organic lower layer coating that has a zinc-based plating film or an aluminum-based plating film on the surface of the temper-rolled cold-rolled steel sheet and does not contain hexavalent chromium on the surface of the plating film. It is formed at a coverage of 0.01 to 1000 / ^{m 2,} an organic resin film containing no hexavalent chromium on the upper layer of the lower layer coating 0.05 g / ^{m 2} or more, at a coverage of less than 0.5 g / ^{m 2} The formed organic coated steel sheet has a peak count RPVC with a wavelength of 100 to 150 μm of the roughness of the surface of the cold rolled steel sheet transferred by a roll of temper rolling, and has an average surface roughness Ra of 200 peak / inch or less. Is an organic-coated steel sheet excellent in corrosion resistance and conductivity. The organic-coated steel sheet having excellent corrosion resistance and conductivity according to claim 2, wherein the lower layer film is a film containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles. The lower layer film includes phosphoric acid and / or a phosphoric acid compound, oxide fine particles, and one or more kinds of metals selected from Mn, Al, Mg, and Ni (provided that they are included as a compound and / or a composite compound) The organic-coated steel sheet having excellent corrosion resistance and conductivity according to claim 2, wherein The peak count number RPVC of the roughness 100 to 150 μm of the roughness of the surface of the cold rolled steel sheet transferred by a roll of temper rolling is 100 peak / inch or less, according to claim 1, 2, 3 or 4 Organic coated steel sheet with excellent corrosion resistance and conductivity. 6. The corrosion resistance and conductivity according to claim 1, 2, 3, 4 or 5, wherein the average surface roughness Ra of the cold rolled steel sheet transferred by a temper rolling roll is 1.1 μm or less. Excellent organic coated steel sheet. The organic coated steel sheet excellent in corrosion resistance and conductivity according to claim 1, 2, 3, 4, 5 or 6, wherein the organic resin film contains a rust preventive additive. The anticorrosion additive according to claim 7, wherein the antirust additive is at least one selected from the following (a1), (a2), (a3), (b), and (c). Organic coated steel sheet with excellent electrical conductivity.
(a1) Calcium and / or calcium compound
(a2) Phosphate
(a3) Silicon oxide
(b) Molybdate
(c) one or more organic compounds selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams The organic coated steel sheet excellent in corrosion resistance and conductivity according to claim 7, wherein the rust preventive additive is at least one selected from the following (a), (b), and (c).
(a) Calcium and / or calcium compound and phosphate and / or silicon oxide
(b) Molybdate
(c) one or more organic compounds selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams The organic-coated steel sheet excellent in corrosion resistance and conductivity according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the organic resin film contains a solid lubricant. The film forming resin of the organic resin film is a reaction product of an epoxy group-containing resin and an active hydrogen-containing compound in which a part or all of the compound is a hydrazine derivative. An organic coated steel sheet having excellent corrosion resistance and conductivity according to 4, 5, 6, 7, 8, 9 or 10.

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