JP2002363768A - Organic-coated steel sheet having excellent corrosion resistance in hot and humid environment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chromium-free organic-coated steel sheet which has excellent black point rust resistance in a hot and humid environment, and further has excellent electric conductivity required for performances such as weldability and groundability. SOLUTION: In the organic-coated steel sheet, in which film defects and the generation of corrosion caused thereby are effectively suppressed by using a cold rolled steel sheet whose surface roughness after skinpass rolling is controlled to a specified range as a steel sheet shock in a specified film constitution, the surface of a cold rolled steel sheet subjected to skinpass rolling is provided with a zinc based or aluminum based plating film, and an organic resin film which does not contain hexavalanet chromium is formed on the surface of the plating film in a coating weight of 0.5 to 5.0 g/m<2> , the count number of crests having a wavelength of 100 to 150 μm in the roughness of the surface of the cold rolled steel sheet RPVC transferred by a rolling roll for skinpass rolling is <=200 peak/inch, and also, the average surface roughness Ra thereof is <=1.5 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic-coated steel sheet suitable for home appliances, building materials, automobiles, etc., which does not contain hexavalent chromium in the coating and has excellent corrosion resistance and conductivity in a high-temperature and high-humidity environment. Organic coated steel sheet.

[0002]

2. Description of the Related Art Steel sheets for household electrical appliances, steel sheets for building materials, steel sheets for automobiles, etc., have conventionally been improved in corrosion resistance (white rust resistance, red rust resistance) on the surface of galvanized steel sheet or aluminum-based steel sheet. For the purpose, steel sheets subjected to chromate treatment with a treatment liquid containing chromic acid, dichromic acid or salts thereof as a main component 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. It is widely used as a surface treatment of steel sheets for applications such as home appliances, automobiles, and building materials. The excellent corrosion resistance of the chromate film is a function of blocking corrosion factors by a dense film of hydrated oxide of trivalent chromium (barrier property).
This is due to the function (self-repairing action) of hexavalent chromium being reduced at the film defect portion to repair the film defect portion.

In the chromate treatment, hexavalent chromium, which is a pollution control substance, is used. This hexavalent chromium is treated in a closed system in the treatment process, is completely reduced and recovered, and is released to the natural world. Never
The treated steel sheet is coated with an organic resin film on the upper layer 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 regulate the content of hexavalent chromium in waste electrical and electronic equipment and end-of-life vehicles, and there is a growing movement to voluntarily reduce the use of hexavalent chromium. is there. As the need for chromium-free chemical conversion-treated steel sheets has increased due to such environmental problems, surface-treated steel sheets having high corrosion resistance using organic composite coatings have been studied. As such a surface-treated steel sheet, for example, JP-A-2001-11656,
JP-A-2001-11645 has been proposed.

On the other hand, manufacturers of AV / OA equipment and home electric appliances are adopting chromium-free chemical conversion treated steel sheets.
The company has moved its production base to Southeast Asia to reduce manufacturing costs. As a result, demand for galvanized steel sheets is growing in Southeast Asia, and exports from domestic blast furnace manufacturers to Southeast Asia are rapidly increasing.At the same time, hot rolled steel sheets, which are used as raw materials, are exported from Japan, and cold-rolled and surface-treated steel sheets are used in Southeast Asia. Local procurement, such as the manufacture of products, is also progressing.

[0005]

However, in Southeast Asia,
Especially in hot and humid areas such as the southern part of China, the rainy season accounts for 80% of the year and is in a different corrosive environment than in Japan.
In such areas, during the transportation and storage of surface-treated steel sheets, a phenomenon in which zinc is locally corroded in a dot-like manner (black spot rust) occurs, which has the problem of impairing the commercial value of the surface-treated steel sheets. Newly found out.

According to the studies made by the present inventors, the mechanism for generating black spot rust as described above is considered as follows. In other words, in the treated film of the surface-treated steel sheet, pits caused by evaporation of water and solvent in the process of drying the applied film-forming composition, defects caused by the surface roughness of the steel sheet, occur when handling the steel sheet. It is considered that there are flaws and the like, and in a high-temperature and high-humidity environment, such a film defect portion becomes a starting point of corrosion of zinc and rust (oxide) of zinc is formed. In particular, in the case of a chromate film, the self-repairing action of hexavalent chromium repairs the film defect, so that black spot rust can be suppressed. However, in the case of a chromium-free coating, such a self-repairing action is obtained. Therefore, generation of black spot rust cannot be suppressed.

Accordingly, an object of the present invention is to provide a chromium-free organic-coated steel sheet which is excellent in corrosion resistance in a high-temperature and high-humidity environment, in particular, black spot rust resistance, and also has excellent conductivity required for performance such as weldability and grounding property. Is to provide.

[0008]

Means for Solving the Problems The present inventors have developed an excellent corrosion resistance (white rust resistance, high temperature and humidity For organic-coated steel sheets that have resistance to black spot rust under environmental conditions), how to suppress the occurrence of film defects, which are the starting point of corrosion such as black spot rust, and how to prevent corrosion from film defects that inevitably occur We examined from the viewpoint of how to control. As a result, using a cold-rolled steel sheet whose surface roughness after temper rolling is restricted to a specific range as a base steel sheet under a specific coating structure, coating defects and associated corrosion (particularly black spot rust) It is important to note that the addition of a specific self-repairing substance instead of hexavalent chromium is particularly effective for corrosion (especially black spot rust) caused by inevitable film defects. understood.

The present invention has been made based on such findings, and the features thereof are as follows. [1] A temper-rolled cold-rolled steel sheet has a zinc-based plating film or an aluminum-based plating film on its surface, and the surface of the plating film has an organic resin film containing no hexavalent chromium of 0.5 to 0.5%.
An organic-coated steel sheet formed with an adhesion amount of 5.0 g / m ² , wherein the peak count number RPVC of a wavelength of 100 to 150 μm of the surface roughness of the cold-rolled steel sheet transferred by the rolling roll of the temper rolling is 200 peak /. An organic-coated steel sheet having excellent corrosion resistance under a high-temperature and high-humidity environment, wherein the steel sheet has an average surface roughness Ra of 1.5 μm or less.

[2] A temper-rolled cold-rolled steel sheet has a zinc-based plating film or an aluminum-based plating film on the surface thereof, and the surface of the plating film does not contain hexavalent chromium. Organic lower layer is 0.01-1000m
g / m ² , and an organic resin film containing no hexavalent chromium is formed on the lower film in an amount of 0.5 to 5.0 g / m ^2.
An organic-coated steel sheet formed with an adhesion amount of ² , and a peak count number RPVC of a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by the rolling roll of the temper rolling is 2
00 peak / inch or less and average surface roughness Ra
An organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment, wherein the thickness of the organic-coated steel sheet is 1.5 μm or less.

[3] The organic coated steel sheet according to the above [2], wherein the lower layer film is a film containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles, and has a corrosion resistance under a high-temperature and high-humidity environment. Excellent organic coated steel sheet. [4] In the organic-coated steel sheet according to the above [2], the lower film is phosphoric acid and / or a phosphoric acid compound, oxide fine particles, Mn,
It is a coating containing at least one metal selected from Al, Mg and Ni (including the case where it is contained as a compound and / or a composite compound). Excellent organic coated steel sheet.

[5] In the organic-coated steel sheet according to any one of the above [1] to [4], the peak count number RPVC having a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by the roll for temper rolling. Is 100 peaks / inch or less, the organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment. [6] The organic-coated steel sheet according to any one of [1] to [5],
An organic coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment, characterized in that the average surface roughness Ra of the cold-rolled steel sheet transferred by the roll of the temper rolling is 1.1 μm or less. [7] The organic-coated steel sheet according to any one of [1] to [6] above,
An organic coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment, characterized in that the organic resin film contains a rust preventive additive.

[8] In the organically coated steel sheet of the above [7], the rust-preventive additive comprises the following (a1), (a2), (a3), (b),
(C) An organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment, characterized in that it is at least one selected from (c). (a1) calcium and / or calcium compound (a2) phosphate (a3) silicon oxide (b) molybdate (c) triazoles, thiols, thiadiazoles,
One or more organic compounds selected from thiazoles and thiurams

[9] The organic coated steel sheet according to the above [7], wherein the rust preventive additive is at least one selected from the following (a), (b) and (c): Organic coated steel sheet with excellent corrosion resistance in humid environment. (a) calcium and / or calcium compound and phosphate and / or silicon oxide (b) molybdate (c) triazoles, thiols, thiadiazoles,
One or more organic compounds selected from thiazoles and thiurams

[10] The organic coated steel sheet according to any one of [1] to [9], wherein the organic resin film contains a solid lubricant, and has excellent corrosion resistance in a high-temperature and high-humidity environment. Coated steel sheet. [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 epoxy-containing resin and an active hydrogen-containing compound in which some or all of the compound is a hydrazine derivative. An organic coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment, characterized by being a reaction product of:

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention and the reasons for limiting the same 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 a specific layer containing no hexavalent chromium as an upper layer of this plating film as necessary. An organic coated steel sheet comprising a lower coating (an inorganic coating, an organic coating or an inorganic-organic coating) formed with a coating amount, and an organic resin coating having a specific coating amount containing no hexavalent chromium formed thereon. The temper-rolled cold-rolled steel sheet, which is a material steel sheet, has a predetermined surface roughness.

Hereinafter, the surface roughness of the temper-rolled cold-rolled steel sheet as the material steel sheet will be described. The present inventors conducted a study on the starting point on the organic coated steel sheet surface where corrosion such as white rust and black spot rust occurs, and as a result, the organic coated steel sheet has a locally thin portion of the organic resin film, It was found that this part was the starting point of white rust and black spot rust. When an extremely thin organic resin film is formed on a steel sheet, a local thin film portion is formed on the organic resin film due to the roughness of the steel sheet surface. This is schematically shown in FIG. 1, and it has been found that such a local thin film portion becomes a starting point of corrosion.

Furthermore, as a result of examining the surface roughness of the steel sheet affecting the formation of the thin film portion of the organic resin film and the factors causing such surface roughness, and further examining the countermeasures, the local roughness of the organic resin film was examined. The surface roughness of a steel sheet such that a thin film portion is formed is generated by being transferred from a rolling roll during temper rolling of a cold-rolled steel sheet. It has been found that by restricting to a specific range, the formation of a local thin film portion can be suppressed and the occurrence of black spot rust or the like can be effectively suppressed.

An organic-coated steel sheet in which a temper-rolled cold-rolled steel sheet is subjected to galvanization and a lower layer film and an organic resin film are sequentially formed on the cold-rolled steel sheet. For the steel sheet and the organic coated steel sheet where no black spot rust was generated, the organic resin film, underlayer film and zinc plating were removed by etching with an acid, and the surface roughness wavelength of the cold rolled steel sheet was measured with a non-contact type roughness meter. FIG. 2 shows the results obtained by organizing the relationship between the wavelength of the roughness of the steel sheet surface and the average surface roughness Ra. According to this, the organic coated steel sheet in which black spot rust has occurred is extremely rough in the wavelength range of 100 to 150 μm as compared to the organic coated steel sheet in which black spot rust has not occurred, and this specific wavelength is exactly It was found that the wavelength of the roughness of the roll surface of the temper rolling roll (in this case, the temper rolling roll finished by electric discharge dulling) was the same as the wavelength. Therefore, to control the surface roughness of the steel sheet after temper rolling,
That is, it was found that the occurrence of black spot rust can be suppressed by controlling the temper rolling conditions (surface roughness of the temper rolling roll, pressure regulation ratio).

FIG. 3 shows a hot and humid environment promotion test shown in an example to be described later for an organic-coated steel sheet using a cold-rolled steel sheet temper-rolled by the above-mentioned roll having a discharge dulling process as a base steel sheet. Wavelength of surface roughness of rolled steel sheet 100 ~
150 μm peak count number RPVC and average surface roughness R
It is the result which investigated about the relationship between a and black spot rust generation of an organic coating steel plate. 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 black spot rust is generated has a peak count number RPVC of the specific wavelength of the surface roughness of the cold-rolled steel sheet transferred from the temper rolling roll of more than 200 peaks / inch, and an average surface. The roughness Ra is distributed over a region of more than 1.5 μm, and the peak count number RPVC of the specific wavelength of the surface roughness of the cold-rolled steel sheet is set to 20.
0 peak / inch or less and average surface roughness Ra ≦
It is understood that black spot rust can be effectively suppressed by controlling the thickness to 1.5 μm. Among them, the average surface roughness R
The range of a ≦ 1.1 μm and the range of the peak count number RPVC of the above specific wavelength of 100 peak / inch or less are particularly excellent in black spot rust resistance. Therefore, by satisfying both of them, the most excellent black spot rust resistance is obtained. It can be seen that the property is obtained.

For the above reasons, 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 adjusted to a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by the temper rolling roll. Mountain count RPVC is 200p
eak / inch or less and the average surface roughness Ra is 1.
It is defined as 5 μm or less. Further, as more preferable ranges 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 surface roughness of the temper-rolled cold-rolled steel sheet is such that the peak count number RPVC of the specific wavelength is 100 peak / in.
and the average surface roughness Ra is most preferably 1.1 μm or less.

As the zinc-based plating film formed on the surface of the cold-rolled steel sheet as described above, besides zinc plating (electrogalvanizing, hot-dip galvanizing) and alloyed hot-dip galvanizing,
There is an alloy plating or the like made of Zn and one or more of elements such as Ni, Cr, Mn, Co, Fe, Al, and Mg. Also,
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
₍₂ dispersion plating) and the like. Further, among the above-mentioned platings, the same type or different types may be plated in two or more layers.

Further, examples of the aluminum-based plating film include aluminum plating and Al-Si alloy plating. Further, the plated steel sheet may be one in which thin steel plating such as Ni is previously applied to the surface of the steel sheet and various platings as described above are applied thereon. As a plating method, any practicable method can be adopted among an electrolysis method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, and a gas phase method.

Further, when an organic resin film as described later is formed on the surface of the plating film, if necessary, the surface of the plating film is alkali-degreased, solvent-degreased, surface-cleaned, etc. A treatment such as a conditioning treatment (an alkaline surface conditioning treatment or an acidic surface conditioning treatment) can be performed. In addition, in order to prevent blackening (a kind of oxidation phenomenon on the plating surface) in the usage environment of the organic coated steel sheet, if necessary, an iron group metal ion (Ni ion, Co ion, Fe ion One or more)
And a surface conditioning treatment with an acidic or alkaline aqueous solution containing When an electrogalvanized steel sheet is used as a base steel sheet, an iron group metal ion (at least one of Ni ion, Co ion, and Fe ion) is added to the electroplating bath for the purpose of preventing blackening, and a plating film is formed. These metals can be contained in an amount of 1 ppm or more. In this case, there is no particular upper limit on the iron group metal concentration in the plating film.

On the surface of the plating film, 6
A lower layer film containing no valent chromium is formed, and an organic resin film is formed on the lower layer (if no lower layer film is formed, the surface of the plating film). As the lower layer film, if it does not contain hexavalent chromium, an inorganic film, an organic film,
Any of inorganic-organic coatings may be used. For example, a crystalline zinc phosphate treated film (inorganic), a film containing amorphous phosphate (inorganic), an alkali silicate film (inorganic), a film containing a polyhydric phenolic compound such as tannic acid (organic) Known films such as trivalent chromium-based chromate film (inorganic) and organic resin-containing trivalent chromium-based chromate film (inorganic-organic), and films obtained by appropriately blending an organic resin with these films. .

For the purpose of further improving the corrosion resistance, the lower layer film is preferably a composite oxide film containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles, more preferably a phosphoric acid and / or a phosphoric acid compound. , Oxide fine particles,
A composite oxide film containing at least one metal selected from Mn, Al, Mg, and Ni (including a compound and / or a composite compound) is preferable.

As the oxide fine particles, silicon oxide (SiO ₂ fine particles) is particularly preferable from the viewpoint of corrosion resistance. Colloidal silica is most preferable among silicon oxides. As colloidal silica, for example, Snowtex O, Snowtex OS, Snowtex OXS, Snowtex OUP, Snowtex AK, Snowtex O40, Snowtex OL, Snowtex OL
40, Snowtex OZL, Snowtex XS, Snowtex S, Snowtex NXS, Snowtex NS, Snowtex N, Snowtex QAS-2
5 (all trade names, manufactured by Nissan Chemical Industries, Ltd.), Cataloid S, Cataloid SI-350, Cataloid SI-40,
Cataroid SA, Cataloid SN (trade name, manufactured by Catalysis Chemical Industry Co., Ltd.), Adelite AT-20-50, Adelite AT-20N, Adelite AT-300, Adelite AT-300S, Adelite AT20Q (all trade names, Asahi Denka Industrial Co., Ltd.) can be used.

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. Further, as the silicon oxide, a material in which dry silica fine particles are dispersed in a coating composition solution can also be used. As the fumed silica, for example, Aerosil 200, Aerosil 300
0, Aerosil 300CF, Aerosil 380 (all trade names, manufactured by Nippon Aerosil Co., Ltd.) and the like can be used.
nm or less is desirable. As the oxide fine particles, in addition to the above silicon oxide, a colloid solution of aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, or the like, fine powder, or the like can also be used.

The phosphoric acid and / or phosphoric acid compound may be, for example, one or two or more of orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid and the like, and metal salts and compounds thereof. Can be blended as a film component. In addition, organic phosphoric acid and salts thereof (for example, phytic acid, phytate,
One or more of phosphonic acids, phosphonates and metal salts thereof may be added. Among them, primary phosphates are preferred from the viewpoint of the stability of the coating composition solution. The form of the phosphoric acid or phosphoric acid compound in the film is not particularly limited, and may be crystalline or non-crystalline. Further, there is no particular limitation on the ionicity and solubility of phosphoric acid and the phosphoric acid compound in the film.

The form in which at least one metal selected from the above-mentioned Mn, Al, Mg and Ni is present in the film is not particularly limited, and may be a metal or an oxide, a hydroxide, a hydrated oxide, It may be present as a compound such as a phosphate compound or a coordination compound or as a complex compound. The ionicity, solubility, and the like of these compounds, hydroxides, hydrated oxides, phosphate compounds, coordination compounds, and the like are not particularly limited. As a method of introducing the metal into the film, Mn, Al, Mg, N
It may be added to the coating composition as phosphate, sulfate, nitrate, chloride or the like of i.

(A) which is a component of the composite oxide film
The molar ratio of the oxide fine particles to (c) one or more metals selected from Mn, Al, Mg, and Ni (including the case where they are included as compounds and / or composite compounds) (a) /
(C) (however, the component (C) is a metal conversion amount of the metal) is preferably 0.1 to 20, and more preferably 0.1 to 10. When the molar ratio (a) / (c) is less than 0.1, the effect of adding the oxide fine particles cannot be sufficiently obtained. On the other hand, when it exceeds 20, the oxide fine particles may hinder the densification of the film.

Further, a constituent component of the composite oxide film,
(B) phosphoric acid and / or a phosphoric acid compound, (c) Mn,
The molar ratio (c) / (b) of one or more metals selected from Al, Mg, and Ni (including the case where they are included as a compound and / or a complex compound) (where component (b) is P
It is preferable that the conversion (in terms of ₂ O ₅ and the component (c) in terms of the amount of metal of the metal) is 0.1 to 1.5. If the molar ratio is less than 0.1, the insoluble property of the composite oxide film is impaired by the soluble phosphoric acid, and the corrosion resistance may be undesirably reduced. On the other hand, if the molar ratio exceeds 1.5, the stability of the processing solution is remarkably reduced, which is not preferable.

An organic resin can be further added to 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. Further, in addition to these water-based resins, water-soluble epoxy resins, water-soluble phenol resins, and water-soluble butadiene rubbers (SBR, NB
R, MBR), a melamine resin, a blocked isocyanate, an oxazoline compound and the like are effective in combination as a crosslinking agent.

In the composite oxide film, as an additive for further improving the corrosion resistance, a polyphosphate,
Phosphates (e.g., zinc phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.), molybdates, phosphomolybdates (e.g., aluminum phosphomolybdate, etc.), organic phosphoric acids and salts thereof (e.g., Phytic acid, phytate, phosphonic acid, phosphonate and their metal salts, alkali metal salts, etc.), organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.), organic compounds (eg, polyethylene glycol, etc.) ) May be blended.

Further, as other additives, organic coloring pigments (eg, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), coloring dyes (eg, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.) ), Inorganic pigments (e.g., titanium oxide, etc.), chelating agents (e.g., thiol, etc.), conductive pigments (e.g., metal powders such as zinc, aluminum, nickel, etc., iron phosphide, antimony dove type tin oxide, etc.), cups One or more of a ring agent (for example, a silane coupling agent, a titanium coupling agent, and the like) and a melamine / cyanuric acid adduct can also be added.

Although the mechanism of corrosion prevention of the composite oxide film as described above is not always clear, the dense and hardly soluble composite oxide film blocks a corrosion factor as a barrier film, and oxide fine particles such as silicon oxide. Can form a stable and dense barrier film with phosphoric acid and / or a phosphoric acid compound and at least one metal selected from Mn, Al, Mg, and Ni. When the oxide fine particles are silicon oxide, It is considered that silicate ions promote formation of basic zinc chloride in a corrosive environment, improve barrier properties, and the like, and thereby provide excellent anticorrosion performance.

The adhesion amount of the lower layer film is 0.01 to 1000 m
g / m ² , preferably 1-600 mg / m ² , more preferably 10-500 mg / m ² . If the amount of the lower layer coating is less than 0.01 mg / m ² , the corrosion resistance is insufficient, while if the amount of adhesion exceeds 1000 mg / m ² , the conductivity is reduced.

Next, the organic resin film formed on the surface of the underlayer film or the plating film will be described. The organic resin film has an adhesion amount of 0.5 g / m ² or more, preferably 0.7 g / m ² or more from the viewpoint of corrosion resistance. The upper limit of the amount of adhesion is 5.0 g / m ² from the viewpoint of conductivity and weldability.
Or less, preferably 3.0 g / m ² or less, more preferably 2.0 g / m ² or less. In the present invention, the range of the amount of the organic resin film adhered is an essential condition for ensuring a good balance between corrosion resistance and conductivity.

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 is coated on its surface with an adhesion amount of 300 mg / m ^2. FIG. 4 shows the results of examining the relationship between the amount of the organic resin film deposited and the corrosion resistance (black spot rust resistance) of the organic coated steel sheet formed and having an organic resin film made of a thermosetting epoxy resin formed thereon. FIG. 5 shows the results of examining the relationship between the adhesion amount of the organic resin film and the conductivity (interlayer resistance according to JIS C 2550). 4 and 5
The test method and evaluation criteria for the corrosion resistance and conductivity of Example 1 were the same as “(1) Corrosion resistance (black spot rust resistance)” and “(2) Conductivity” in Examples described later. According to FIG. 4, as the amount of the organic resin film attached increases, the corrosion resistance in a high-temperature and high-humidity environment improves, and the amount of the attached organic resin film is 0.5 g / m ² or more, preferably 0.1 g / m ² or more.
By setting it to 7 g / m ² or more, excellent corrosion resistance (black spot rust resistance) is obtained. According to FIG. 5, when the amount of the organic resin film adhered exceeds 5.0 g / m ² , the conductivity is remarkably reduced. Further, by setting the amount of adhesion to 3.0 g / m ² or less, more preferably 2.0 g / m ² or less, particularly excellent conductivity is obtained.

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. Also, a water-soluble resin, a water-dispersible resin,
Any of organic solvent-soluble resins may be used. Further, an organic composite silicate obtained by compounding an organic resin with silica via a silane coupling agent is also suitable.

As the film forming resin of the organic resin film, for example, the following can be used. (1) Epoxy resin For example, epichlorohydrin type, glycidyl ether type etc. 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 Resins, 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 to organic resin films,
Paintability can be imparted.

(2) Urethane resin For example, oil-modified polyurethane resin, alkyd-based polyurethane resin, polyester-based polyurethane resin, polyether-based urethane resin, polycarbonate-based polyurethane resin and 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, etc. Can be used.

(4) Acrylic Silicone Resin For example, an acrylic copolymer containing a hydrolyzable alkoxysilyl group on the side chain or terminal of an acrylic copolymer and a curing agent added thereto can be used. When these acrylic silicone resins are used, excellent weather resistance of the organic resin film can be expected. (5) Fluororesins There are fluoroolefin-based copolymers, such as alkyl vinyl ether, synchroalkyl vinyl ether, carboxylic acid-modified vinyl ester, hydroxyalkyl allyl ether, tetrafluoropropyl vinyl ether, etc. A copolymer with (fluoroolefin) can be used. When these fluororesins are used, excellent weather resistance and excellent hydrophobicity of the organic resin film can be expected.

(6) Acrylic resin For example, polyacrylic acid and its copolymer, polyacrylate and its copolymer, polymethacrylate and its copolymer, polymethacrylate and its copolymer, A urethane-acrylic acid copolymer (or urethane-modified acrylic resin), a styrene-acrylic acid copolymer, or the like can be used, and a resin obtained by modifying these resins with another alkyd resin, an epoxy resin, a phenol resin, or the like. Can also be used.

(7) Ethylene resin (polyolefin resin) For example, ethylene copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, carboxyl-modified polyolefin resin, and ethylene-unsaturated carboxylic acid copolymer Coalescence, an ethylene ionomer, or the like can be used, and a resin obtained by modifying these resins with another alkyd resin, an epoxy resin, a phenol resin, or the like can also be used.

When a water-dispersible resin is used, the core portion and the shell portion of the resin particles are made of different types of resins or cores made of resins having different glass transition temperatures in order to lower the drying temperature of the resin. -A shell-type water-dispersible resin can be used. In addition, a water-dispersible resin having a self-crosslinking property, for example, a water-dispersible resin in which an alkoxysilane group is provided to resin particles can also be used.By using such a water-dispersible resin, the resin can be heated and dried. It is possible to utilize the formation of silanol groups by hydrolysis of alkoxysilane and the crosslinking between resin particles by a dehydration condensation reaction of silanol groups between resin particles.

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.
The thermosetting resin includes, as a curing agent, urea resin (butylated urea resin or the like), melamine resin (butylated melamine resin), butylated urea / melamine resin, amino resin such as benzoguanamine resin, block isocyanate, An oxazoline compound, a phenol resin or the like can be blended.

Among the above-mentioned film-forming resins, epoxy resins and epoxy resins are preferred from the viewpoints of corrosion resistance, workability and coatability of the organic film.
Ethylene resins are preferable, and among them, thermosetting epoxy resins and modified epoxy resins having excellent barrier properties against corrosion factors such as oxygen are particularly preferable. For example,
Thermosetting epoxy resin, thermosetting modified epoxy resin, acrylic copolymer resin copolymerized with epoxy group-containing monomer, polybutadiene resin having epoxy group, polyurethane resin having epoxy group, and adduct of these resins or Condensates and the like can be mentioned, and one type of these epoxy group-containing resins can be used alone, or two or more types can be mixed and used.

Among these epoxy group-containing resins, an epoxy group-containing resin modified with a hydrazine derivative,
That is, a reaction product of an epoxy group-containing resin such as the above-described epoxy resin or modified epoxy resin and an active hydrogen-containing compound in which some or all of the compounds are hydrazine derivatives is particularly preferable. Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy group-containing resin include, for example, those shown below, and one or more of these can be used. A part (preferably all) needs to be a hydrazine derivative having active hydrogen.・ Hydrazine derivative having active hydrogen ・ Primary or secondary amine compound having active hydrogen ・ Organic acid such as ammonia or carboxylic acid ・ Halogen halide such as hydrogen chloride ・ Alcohols, thiols ・ Has active hydrogen Quaternary chlorinating agents which are hydrazine derivatives or mixtures of tertiary amines and acids

Examples of the hydrazine derivative having an active hydrogen include the following. Carbohydrazide, propionic hydrazide, salicylic hydrazide, adipic dihydrazide, sebacic dihydrazide, dodecanoic dihydrazide, isophthalic dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, benzophenone hydrazide, aminopolyacrylamide such as benzophenone hydrazide Compounds; pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;

1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,2
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-methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindo Triazole compounds such as lysine;

5-phenyl-1,2,3,4-tetrazole, 5-mercapto-1-phenyl-1,2,2,
Tetrazole compounds such as 3,4-tetrazole; thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole; maleic hydrazide; Pyridazine compounds such as methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone Also, among these, Pyrazole compounds and triazole compounds having a 5- or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly preferred. These hydrazine derivatives can be used alone or in combination of two or more.

Representative examples of the amine compound having active hydrogen which can be used as a part of the active hydrogen-containing compound include the following. The primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine can be converted to ketone, aldehyde or carboxyl. Acid and eg 1
A compound denatured to aldimine, ketimine, oxazoline or imidazoline by a heating reaction at a temperature of about 00 to 230 ° C;

Diethylamine, diethanolamine, di-n- or -iso-propanolamine, N
A secondary monoamine such as methylethanolamine or N-ethylethanolamine; a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction. Monoethanolamine, neopentanolamine,
2-aminopropanol, 3-aminopropanol, 2
A compound in which the primary amino group of an alkanolamine such as -hydroxy-2 '(aminopropoxy) ethyl ether is modified to ketimine;

The quaternary chlorinating agents which can be used as a part of the active hydrogen-containing compound include hydrazine derivatives having no active hydrogen or tertiary amines, which themselves have no reactivity with epoxy groups. It is a mixture with an acid in order to be able to react with. The quaternary chlorinating agent reacts with an epoxy group in the presence of water if necessary, to form a quaternary salt with the 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. Further, as a hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent, for example, 3,6-dichloropyridazine and the like, and as a tertiary amine, for example, dimethylethanolamine, triethylamine, Trimethylamine, triisopropylamine, methyldiethanolamine and the like can be mentioned.

The reaction product 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 obtained by reacting the epoxy group-containing resin and the active hydrogen-containing compound at 10 to 300 ° C. Preferably, it is obtained by reacting at 50 to 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 used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone and cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether Alcohols and ethers having a hydroxyl group such as propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether; esters such as ethyl acetate, butyl acetate and ethylene glycol monobutyl ether acetate; toluene, xylene Such as aromatic hydrocarbons. It can be used one or two or more thereof. Among these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, coatability, and the like.

The mixing ratio of the epoxy group-containing resin and the active hydrogen-containing compound in which a part or all of the compound is a hydrazine derivative having active hydrogen is such that the ratio of the solid content to the epoxy group-containing resin is 100 parts by weight. 0.5 to 20 parts by weight of the hydrogen-containing compound, particularly preferably 1.0 to 10 parts by weight
It is desirable to use parts by weight. The mixing ratio of the epoxy group-containing resin to 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 [the number of active hydrogen groups / the number of epoxy groups] is 0. .
It is suitably from 01 to 10, more preferably from 0.1 to 8, still more preferably from 0.2 to 4, from the viewpoint of corrosion resistance and the like.

The proportion of the hydrazine derivative having active hydrogen in the active hydrogen-containing compound is suitably from 10 to 100 mol%, more preferably from 30 to 100 mol%, and still more preferably from 40 to 100 mol%. . If the proportion of the hydrazine derivative having active hydrogen is less than 10 mol%, a sufficient rust-preventing function cannot be imparted to the organic film, and the obtained rust-preventing effect is obtained by simply mixing the hydrazine derivative with the film-forming organic resin. There is no big difference from the case.

Although the mechanism of corrosion prevention by the organic resin film made of such a specific reaction product is not necessarily clear, the mechanism can be estimated as follows. That is, by providing a hydrazine derivative to the film-forming organic resin, (1) the effect of blocking corrosion factors such as oxygen and chloride ions by a dense organic polymer film is obtained,
(2) The hydrazine derivative can firmly bind to the surface of the lower film to form a stable passivation layer. (3) The free hydrazine derivative in the film traps zinc ions eluted by the corrosion reaction, Due to the formation of the insoluble chelate compound layer, the formation of an ion conductive layer at the interface is suppressed and the progress of corrosion is suppressed, and the progress of corrosion is effectively suppressed by such effects as excellent corrosion resistance is obtained. It is thought that it is possible.

When an epoxy group-containing resin is used in particular as the film-forming organic resin, a dense barrier film is formed by the reaction between the epoxy group-containing resin and the cross-linking agent. It is considered that the resin has excellent permeation suppression ability, and a hydroxyl group in the molecule provides an excellent bonding force with the substrate, so that particularly excellent corrosion resistance can be obtained. Further, 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.

A rust preventive additive or a solid lubricant can be added to the organic resin film as needed. As the rust-preventive additive to be added to the organic resin film, the following rust-preventive additives having an effective self-repairing action (a1), (a2), (a
It is preferable to use at least one selected from 3), (b) and (c), whereby the corrosion resistance of the inevitable coating defect can be effectively improved. (A1) calcium and / or calcium compound (a2) phosphate (a3) silicon oxide (b) molybdate (c) one selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams Organic Compounds Above Also, regarding the rust preventive additives (a1) to (a3),
Composite addition of (a1) and (a2) and / or (a3) is particularly desirable from the viewpoint of improving corrosion resistance.

The above (a1) to (a3) are contained in the organic resin film.
The corrosion prevention mechanism obtained by blending each of the rust preventive additives (b) and (c) is as follows. First, the above (a1)
Each of the rust-preventive additives (a) to (a3) develops self-repairing property of a film defect part by a precipitation action. In addition, (a1) and (a2)
It is considered that the reaction mechanism in the case where or and / or (a3) is added in combination is proceeded by the following steps. [First step]: Under a corrosive environment, calcium, which is more noble than zinc or aluminum, which is a plating metal, is preferentially dissolved. [Second step]: When the above (a1) is added in combination with the phosphate of (a2), phosphate ions dissociated by the hydrolysis reaction and calcium preferentially dissolved in the first step are used. The ions undergo a complexing reaction. Further, in the case of the silicon oxide (a3) that is added in combination with the above (a1), calcium ions preferentially dissolved in the first step are adsorbed on the surface of the silicon oxide, and the surface charge is electrically transferred. Neutralizes and aggregates. As a result, in each case, a dense and hardly soluble protective film is formed, which blocks the corrosion starting point to suppress the corrosion reaction.

The rust preventive additive (b) exhibits self-repairing properties due to a 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 blocks a corrosion starting point, thereby suppressing a corrosion reaction. Further, the rust-preventive additive (c) exhibits self-repairing property due to an adsorption effect. That is, the zinc or aluminum eluted by the corrosion is adsorbed on the nitrogen or sulfur-containing polar group contained in the above (c) to form an inert film, which blocks the corrosion starting point to suppress the corrosion reaction.

The calcium compound (a1) may be any of salts, hydroxides and oxides, and one or more of these calcium compounds and metallic calcium can be used. There is no particular limitation 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 / magnesium phosphate, etc. Double salts containing other cations may be used.

The phosphate of the above (a2) includes all kinds of salts such as single salts and double salts. The metal cations constituting the metal cations are not limited, and may be any of metal cations such as zinc phosphate, magnesium phosphate, calcium phosphate, and aluminum phosphate. The phosphate ion skeleton and the degree of condensation are not limited, and may be any of normal salts, dihydrogen salts, monohydrogen salts or phosphites. Includes all condensed phosphates such as acid salts.

The silicon oxide (a3) may be either colloidal silica or dry silica. Further, among silicon oxides, ion-exchange silica in which metal ions such as calcium are bonded to the surface thereof is particularly desirable. Ion-exchanged silica is obtained by fixing metal ions such as calcium ions on the surface of a porous silica gel powder. The metal ions are released under a corrosive environment to form a precipitated film. In addition, calcium ion exchange silica is most preferable among the ion exchange silica. As calcium ion exchange silica, for example, SHIELDEX C303, SHIELDEX AC3, SHIELDEX
AC5 (brand name, manufactured by WRGrace & Co.), SHIELDEX, SH
IELDEX SY710 (Trade name, Fuji Silysia Chemical Ltd.)
Manufactured).

Further, particularly excellent corrosion resistance can be obtained by adding ion-exchanged silica (particularly preferably calcium ion-exchanged silica) in combination with fine-particle silica.
The particulate silica may be either colloidal silica or fumed silica. When colloidal silica is based on a water-based film-forming resin, for example, Snowtex O, Snowtex N, Snowtex 20, Snowtex 30, Snowtex 40, Snowtex C, Snowtex S (all trade names, Nissan Chemical Co., Ltd.
And when the solvent-based film-forming resin is used as a base, for example, an organosilica sol MA
-ST-M, organosilica sol IPA-ST, organosilica sol EG-ST, organosilica 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 (all trade names, manufactured by Nissan Chemical Industries, Ltd.) and the like can be used.

As the fumed silica, AEROSI
LR971, AEROSILR R812, AEROSILR R811, AE
ROSILR R974, AEROSILR R202, AEROSILR R8
05, AEROSILR 130, AEROSILR 200, AEROSILR
AEROSILR 300CF (trade name, manufactured by Nippon Aerosil Co., Ltd.) or the like can be used.

These fine silica particles contribute to the formation of a dense and stable zinc corrosion product in a corrosive environment, and the corrosion product is formed densely on the plating surface to suppress the promotion of corrosion. It is considered that a particularly excellent anticorrosion effect can be obtained by combining such an anticorrosion mechanism with the anticorrosion mechanism of ion exchange silica described above.
The mixing 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, and more preferably 90 /.
Suitably, it is 10-60 / 40. Weight ratio (x) / of ion exchange silica (x) and fine particle silica (y)
In both cases where (y) is less than 1/99 or more than 99/1, the effect of the combined addition of the two cannot be sufficiently obtained.

The molybdate of the above (b) is not limited in its skeleton and degree of condensation, and includes, for example, orthomolybdate, paramolybdate, metamolybdate and the like. Further, it includes all salts such as a single salt and a double salt, and examples of the double salt include molybdate phosphate and the like. Among the organic compounds of the above (c), triazoles include:
1,2,4-triazole, 3-amino-1,2,4-
Triazole, 1H-benzotriazole, etc.
As thiols, 1,3,5-triazine-2,
4,6-trithiol, 2-mercaptobenzimidazole and the like, and as the thiadiazoles, 5-amino-2-mercapto-1,3,4-thiadiazole,
2,5-dimercapto-1,3,4-thiadiazole and the like; thiazoles such as 2-N, N-diethylthiobenzothiazole and 2-mercaptobenzothiazole; and thiurams as tetraethyl And thiuram disulfide.

(A1) to (a3), (b) and (c) described above
As described above, in the corrosive environment, (a1) to (a3) are due to the precipitation effect, (b) is due to the passivation effect, and (c) is the adsorption The protective film is formed by each effect. The amount of the rust preventive additives (a1) to (a3), (b) and (c) in the organic resin film is 100 parts by weight (solid content) of the resin component in the film.
To 1 to 100 parts by weight (solid content), preferably 5 to 80 parts by weight (solid content), more preferably 10
It is appropriate that the content be 50 parts by weight (solid content). If the total amount of the rust preventive additives (a1) to (a3), (b), and (c) is less than 1 part by weight, the effect of improving corrosion resistance is small. On the other hand, if the amount exceeds 100 parts by weight, both the corrosion resistance and the conductivity are undesirably reduced.

Further, in addition to the above-mentioned rust preventive additive (self-repair developing substance) in the organic resin film, as a corrosion inhibitor,
Other oxide fine particles (eg, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate (eg, aluminum phosphomolybdate, etc.), organic phosphoric acid or a salt thereof (eg,
Phytic acid, phytate, phosphonic acid, phosphonate, and their metal salts, alkali metal salts, alkaline earth metal salts, etc.), organic inhibitors (hydrazine derivatives,
Thiol compounds, dithiocarbamates and the like).

In order to improve the workability of the film,
If necessary, a solid lubricant can be blended in the organic resin film. As solid lubricants applicable to the present invention,
For example, the following may be mentioned, and one or more of these may be used. (1) Polyolefin wax, paraffin wax:
For example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc. (2) Fluororesin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.), polyvinyl fluoride resin, polyvinylidene fluoride Resin, etc.

In addition, fatty acid amide compounds (eg, stearic acid amide, palmitic acid amide,
Methylenebisstearamide, ethylenebisstearamide, oleic amide, esylamide, alkylenebisfatty acid amide, etc.), metallic soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metals One or more of sulfides (molybdenum disulfide, tungsten disulfide, etc.), graphite, fluorinated graphite, boron nitride, polyalkylene glycol, alkali metal sulfate and the like may be used.

Among the above solid lubricants, polyethylene wax and fluororesin compounds (among others, polytetrafluoroethylene resin fine particles) are particularly preferable. Examples of polyethylene wax include Seridust 9615A, Seridust 3715, Seridust 3620, Seridust 3910
(Trade name, manufactured by Hoechst), Sunwax 131-
P, Sunwax 161-P (trade name, manufactured by Sanyo Chemical Co., Ltd.), Chemipearl W-100, Chemipearl W-2
00, Chemipearl W-500, Chemipearl W-800,
Chemipearl W-950 (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) or the like can be used.

As the fluororesin fine particles, particularly, tetrafluoroethylene fine particles are most suitable. For example, Lubron L-2, Lubron L-5 (trade names, manufactured by Daikin Industries, Ltd.), MP1100, MP1200 (trade names) Product name, manufactured by DuPont Mitsui), Fullon Dispersion AD1, Fullon Dispersion AD2, Fullon L140J, Fullon L150J, Fullon L15
5J (trade name, manufactured by Asahi IC Fluoropolymers Co., Ltd.) and the like are preferable. Also, among these,
Particularly excellent lubricating effects are obtained when polyolefin wax and tetrafluoroethylene are used in combination.

The compounding amount of these solid lubricants is preferably 1 to 80 parts by weight based on 100 parts by weight (solid content) of the resin component in the film. If the amount of the solid lubricant is less than 1 part by weight, the lubricating effect is poor, and if it is more than 80 parts by weight, the paintability is reduced. The preferred amount is 3 to 40 parts by weight.

Further, if necessary, as other additives, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.) and coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo dyes, etc.) Metal dyes, etc.), inorganic pigments (e.g., titanium oxide, etc.), chelating agents (e.g.,
Thiol), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, etc., iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, silane coupling agents, titanium coupling agents, etc.), Melamine / cyanuric acid adducts and the like can be added.

To produce the organic-coated steel sheet of the present invention, the cold-rolled steel sheet transferred by the temper-rolling roll is prepared by temper-rolling the cold-rolled steel sheet using a roll having adjusted surface roughness. The peak count number RPVC of the surface roughness having 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.
Make sure that: A zinc-based or aluminum-based plating is applied to the cold-rolled steel sheet after such temper rolling, and a composition (solution, )
Is applied and dried by heating, and then a composition (solution) for an organic resin film is applied and dried by heating.

When forming an underlayer coating, a composition (solution)
Is 0.01 to 1000 mg / m ² , preferably 1 to 600 mg / m ² , more preferably 10 to
It is applied to a concentration of 500 mg / m ² and dried. The method of applying the composition (solution) for the lower layer coating on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet may be any of an application method, an immersion method, and a spray method. Also,
In the application method, any application means such as a roll coater (three-roll method, two-roll method, etc.), a squeeze coater, a die coater and the like may be used. In addition, after the application treatment using a squeeze coater or the like, the dipping treatment or the spray treatment, the application amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by an air knife method or a roll drawing method. Usually, after the application of the composition (solution), heating and drying are performed without rinsing with water, but in some cases, rinsing with water may be performed after the application.

The method of heating and drying the applied composition (solution) is arbitrary, and for example, a means such as a dryer, a hot air oven, a high-frequency induction heating oven, and an infrared oven can be used.
The heating and drying treatment is performed at a plate temperature of 40 to 350C, preferably 70C to 200C, and more preferably 70C to 160C.
It is appropriate to carry out within the range. This heating and drying temperature is 4
If the temperature is lower than 0 ° C., a large amount of water remains in the film, so that the corrosion resistance tends to be insufficient. On the other hand, if the temperature is higher than 350 ° C., the film is not only uneconomical, but also cracks and the like are generated in the film, and the corrosion resistance is liable to deteriorate.

When an organic resin film is formed, the composition (solution) is applied in an amount of 0.5 to 5.0 g / m ² , preferably 0.7 to 3.0 g / m ^2, more preferably 0 to 3.0 g / m ² after drying. .7
The coating is to 2.0 g / ^{m 2} and heated and dried.
The composition (solution) for an organic film is composed of the above-mentioned respective components of the film and an organic solvent and / or water, and a neutralizing agent, a lubricity-imparting agent, a rust-preventive additive and the like are added thereto in an appropriate amount, if necessary. It can be contained.

The method of applying the composition (solution) for an organic film to the surface of a zinc-based steel sheet or an aluminum-based steel sheet or to the upper layer of the lower film may be any of a coating method, a dipping method, and a spray method. In the coating method, any coating means such as a roll coater (three-roll method, two-roll method, etc.), a squeeze coater, a die coater, etc. may be used. In addition, after the application treatment using a squeeze coater or the like, the dipping treatment or the spray treatment, the application amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by an air knife method or a roll drawing method. Usually, after the application of the composition (solution), heating and drying are performed without rinsing with water, but in some cases, rinsing with water may be performed after the application.

The method of heating and drying the applied composition (solution) is arbitrary, and for example, a means such as a dryer, a hot air oven, a high frequency induction heating oven, an infrared oven and the like can be used.
The heating and drying treatment is suitably performed at a temperature of 50 to 350 ° C., preferably 60 to 250 ° C. at the reached plate temperature. If the heating and drying temperature is lower than 50 ° C., a large amount of organic solvent and water remains in the film, so that the corrosion resistance tends to be insufficient.
When the temperature exceeds 50 ° C., not only is it uneconomical, but also the coating is liable to have defects and the corrosion resistance tends to be reduced.

[0085]

[Example] Resin composition (reaction product) for forming an organic film
Was synthesized as follows. [Synthesis Example 1] 1870 parts of EP828 (manufactured by Yuka Shell Epoxy, epoxy equivalent: 187) and bisphenol A91
Two parts, 2 parts of tetraethylammonium bromide and 300 parts of methyl isobutyl ketone were charged into a four-necked flask, heated to 140 ° C., and reacted for 4 hours to obtain an epoxy resin having an epoxy equivalent of 1,391 and a solid content of 90%. Add ethylene glycol monobutyl ether 150
After adding 0 parts, the mixture was 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 mixture was reacted for 6 hours until the epoxy group disappeared. While cooling, 205 parts of methyl isobutyl ketone was added to obtain a pyrazole-modified epoxy resin having a solid content of 60%. This is a resin composition (1)
And 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.

[Synthesis Example 2] A four-necked flask was charged with 4000 parts of EP1007 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 2000) and 2239 parts of ethylene glycol monobutyl ether, and was heated to 120 ° C and completely heated in 1 hour. The epoxy resin was dissolved. This was cooled to 100 ° C., and 3-amino-1,2,4-triazole (molecular weight: 8
After adding 168 parts of 4) and reacting for 6 hours until the epoxy group disappeared, 540 parts of methyl isobutyl ketone was added with cooling to obtain a modified triazole epoxy resin having a solid content of 60%. This is designated as a resin composition (2). This resin composition (2) comprises a film-forming organic resin (A) and 100 mol of a hydrazine derivative (C) having active hydrogen.
% Of the active hydrogen-containing compound.

[Synthesis Example 3] A four-necked flask was charged with 222 parts of isophorone diisocyanate (isocyanate equivalent weight: 111) and 34 parts of methyl isobutyl ketone.
Keeping at 0 ° C, methyl ethyl ketoxime (molecular weight 87) 8
After dropping 7 parts over 3 hours, the mixture was kept at 40 ° C. for 2 hours to obtain a partially blocked isocyanate having an isocyanate equivalent of 309 and a solid content of 90%.

Subsequently, 1496 parts of EP828 (manufactured by Yuka Shell Epoxy, epoxy equivalent: 187), 684 parts of bisphenol A, tetraethylammonium bromide 1
Parts and 241 parts of methyl isobutyl ketone were charged into a four-necked flask, heated to 140 ° C. and reacted for 4 hours 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 the mixture was cooled to 100 ° C. to give 3-mercapto-1,
After 202 parts of 2,4-triazole (molecular weight 101) was added and reacted for 6 hours until the epoxy group disappeared, 230 parts of the above partially blocked isocyanate having a solid content of 230% was added.
The mixture was reacted at 100 ° C. for 3 hours, and it was confirmed that the isocyanate group had disappeared. Further, 461 parts of ethylene glycol monobutyl ether was added to obtain a modified triazole epoxy resin having a solid content of 60%. This is referred to as a 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.

[Synthesis Example 4] 1870 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 187), 912 parts of bisphenol A, 2 parts of tetraethylammonium bromide, and 300 parts of methyl isobutyl ketone were charged into a four-necked flask and heated to 140 ° C. Raise the temperature and let it react for 4 hours.
An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. After adding 1500 parts of ethylene glycol monobutyl ether, the mixture was cooled to 100 ° C., 258 parts of dibutylamine (molecular weight: 129) was added, and the mixture was reacted for 6 hours until the epoxy group disappeared. Add 225 parts of ketone, 60% solids
Was obtained. This is referred to as a 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.

As organic-coated steel sheets for household appliances, building materials, and automobile parts, the average roughness Ra is different from the peak count number RPVC of the wavelength of 100 to 150 μm of the surface roughness of the steel sheet transferred by the roll of temper rolling. Various zinc-based platings or aluminum-based platings shown in Table 1 were applied to the cold-rolled steel sheets, and used as processing original sheets. In addition, the thing of predetermined | prescribed sheet thickness was employ | adopted for the cold rolled steel plate according to the objective of evaluation. After alkaline degreasing, washing and drying the surface of this plated steel sheet,
The compositions (solutions) for the lower layer coating shown in Tables 2 and 3 were applied by a roll coater and then dried by heating. The adhesion amount of the lower layer coating was adjusted by changing the solid content (heating residue) of the coating composition or the coating conditions (roll rolling force, rotation speed, etc.).

Next, a composition (solution) for an organic resin film was applied to the upper layer of the lower layer film by a roll coater and dried by heating. Table 4 shows the composition (solution) for the organic film.
If necessary, a rust preventive additive (self-repairing substance) shown in Table 6 and a solid lubricant shown in Table 7 are blended with the resin composition shown in Table 5, and this is dispersed in a paint dispersing machine (sand grinder).
Tables 8 and 9 obtained by stirring and grinding for the required time using
Was used. The amount of the organic resin film adhered was adjusted by changing the solid content of the composition (residual residue after heating) or the application conditions (roll rolling force, rotation speed, etc.).

The organic-coated steel sheet thus obtained was evaluated for corrosion resistance (black spot rust resistance) and conductivity by the following test methods. In addition, the organic resin film, lower layer film, and plating film of the organic coated steel plate subjected to the test were removed by etching with an acid, and the surface roughness of the cold-rolled steel plate was measured with a non-contact type roughness meter. Mountain count number R of 100 to 150 μm
The PVC and the 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.

(1) Corrosion resistance (black spot rust resistance) A test piece having a size of 70 mm × 150 mm was subjected to a high temperature and high humidity environment acceleration test condition (60 ° C. × 98 RH%) for a predetermined period (500 ° C.).
Time and 1000 hours), 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 ○ +: Black spot rust 1 to 2 ○: Black spot rust 3 to 5 ○-: Black spot rust 6 to 10 △: Black spot rust 11 to 50 ×: Black spot rust more than 50

(2) Conductivity The interlayer insulation resistance of each test piece was measured in accordance with JIS C 2550 and evaluated according to the following criteria. ◎: 2Ω · cm ² / sheet or less ○: more than 2Ω · cm ² / sheet and 3Ω · cm ² / sheet or less ○ −: more than 4Ω · cm ² / sheet and 5Ω · cm ² / sheet or less ×: 5Ω · cm ² / More than

[0095]

[Table 1]

[0096]

[Table 2]

[0097]

[Table 3]

[0098]

[Table 4]

[0099]

[Table 5]

[0100]

[Table 6]

[0101]

[Table 7]

[0102]

[Table 8]

[0103]

[Table 9]

[0104]

[Table 10]

[0105]

[Table 11]

[0106]

[Table 12]

[0107]

[Table 13]

[0108]

[Table 14]

[0109]

[Table 15]

[0110]

[Table 16]

[0111]

As described above, the organic coated steel sheet of the present invention has excellent corrosion resistance in a high-temperature and high-humidity environment, and has excellent electrical conductivity, even though the coating does not contain hexavalent chromium at all. It has nature.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a cross section of an organic coated steel sheet on which a local thin film portion caused by the surface roughness of a cold-rolled steel sheet is formed.

Fig. 2 Galvanizing cold-rolled steel sheet that has been temper-rolled,
An organic coated steel sheet in which a lower layer film and an organic resin film are sequentially formed on the upper layer, wherein an organic coated steel sheet having black spot rust in the high temperature and high humidity environment promotion test and an organic coated steel sheet having no black spot rust, a cold rolled steel sheet Graph showing the relationship between the wavelength of surface roughness and the average surface roughness

FIG. 3 shows an organic-coated steel sheet using a temper-rolled cold-rolled steel sheet as a base steel sheet, the wavelength of the surface roughness of the cold-rolled steel sheet being 100 to
150 μm peak count number RPVC and average surface roughness R
Graph showing the relationship between a and the occurrence of black spot rust on the organic coated steel sheet

FIG. 4 shows a galvanized cold-rolled steel sheet whose surface roughness satisfies the conditions of the present invention after temper rolling, 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 attached and corrosion resistance (black spot rust resistance) for an organic coated steel sheet with an organic resin film formed

FIG. 5 shows a galvanized cold-rolled steel sheet whose surface roughness after temper rolling satisfies the conditions of the present invention, an inorganic lower layer film formed thereon, and a thermosetting epoxy resin further formed thereon. Graph showing the relationship between the adhesion amount of the organic resin film and the conductivity of the organic coated steel sheet on which the organic resin film was formed.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 22/07 C23C 22/07 22/56 22/56 28/00 28/00 C (72) Inventor Kubota Takahiro 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masaaki Yamashita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 4D075 AE03 AE27 BB05X BB87Y BB91X BB92Z CA09 CA13 CA22 CA33 DA06 DB05 DB07 DC01 DC11 DC18 EA06 EA07 EA10 EA37 EB02 EB12 EB13 EB14 EB16 EB19 EB20 EB22 EB32 BD33 EB33 EB35 EB36 EB38 A18 ECA ECA ECA ECA ECA ECA ECA ECA ECA AA19D AA20C AA24D AB03A AB10B AB18B AH03C AK01C AK01D CA14C CB00C CB00D DD07A EH71B YY00A 4K026 AA02 AA13 AA22 BA03 BA12 BB08 CA26 CA37 CA41 DA02 DA11 4K044 AA 02 AB02 BA10 BB03 BB04 BC02 CA11 CA16 CA18

Claims (11)

[Claims] 1. A temper-rolled cold-rolled steel sheet having a zinc-based plating film or an aluminum-based plating film on the surface thereof, and an organic resin film containing no hexavalent chromium on the surface of the plating film having a thickness of 0.5 to 5 mm. An organic-coated steel sheet formed with an adhesion amount of 0.0 g / m ² , wherein the peak count number RPV having a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by the rolling roll of the temper rolling.
An organic-coated steel sheet having excellent corrosion resistance under a high-temperature and high-humidity environment, wherein C is 200 peaks / inch or less and average surface roughness Ra is 1.5 μm or less. 2. A temper-rolled cold-rolled steel sheet having a zinc-based plating film or an aluminum-based plating film on a surface thereof, wherein the surface of the plating film does not contain hexavalent chromium and is an inorganic, organic, or inorganic-organic material. 0.01 to 1000mg of lower layer coating
/ ^M is formed at a coverage of ^2, the organic resin film is 0.5 to 5.0 g / ^{m 2} which does not contain hexavalent chromium in the upper layer of the lower layer film
Of the surface of the cold-rolled steel sheet transferred by the rolling roll of the temper rolling, the peak count number RPVC of the wavelength of 100 to 150 μm transferred by the roll of the temper rolling is 20.
An organic-coated steel sheet excellent in corrosion resistance under a high-temperature and high-humidity environment, characterized in that the steel sheet has an average surface roughness Ra of not more than 0 peak / inch and an average surface roughness of not more than 1.5 μm. 3. The organic coating according to claim 2, wherein the lower coating is a coating containing phosphoric acid and / or a phosphoric acid compound and oxide fine particles. steel sheet. 4. The undercoating film is composed of phosphoric acid and / or a phosphoric acid compound, oxide fine particles, and at least one metal selected from Mn, Al, Mg, and Ni (provided that the compound and / or composite compound The organic-coated steel sheet having excellent corrosion resistance under a high-temperature and high-humidity environment according to claim 2, characterized in that the coated steel sheet comprises a film containing the same. 5. The peak count number RPVC having a wavelength of 100 to 150 μm of the roughness of the surface of the cold-rolled steel sheet transferred by the roll of the temper rolling is 100 peaks / inch or less. The organic-coated steel sheet having excellent corrosion resistance under a high-temperature and high-humidity environment according to 3 or 4. 6. The cold-rolled steel sheet transferred by the rolling roll of the temper rolling has an average surface roughness Ra of 1.1 μm or less, according to claim 1, 2, 3, 4, or 5. Organic coated steel sheet with excellent corrosion resistance under high temperature and high humidity environment. 7. The organic coating having excellent corrosion resistance in a high-temperature and high-humidity environment according to claim 1, wherein the organic resin film contains a rust preventive additive. steel sheet. 8. The rust preventive additive according to the following (a1), (a2),
The organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment according to claim 7, wherein the organic-coated steel sheet is at least one selected from (a3), (b), and (c). (a1) calcium and / or calcium compound (a2) phosphate (a3) silicon oxide (b) molybdate (c) triazoles, thiols, thiadiazoles,
One or more organic compounds selected from thiazoles and thiurams 9. The rust preventive additive according to the following (a), (b), (c)
The organic coated steel sheet having excellent corrosion resistance under a high-temperature and high-humidity environment according to claim 7, wherein the organic-coated steel sheet is at least one member selected from the group consisting of: (a) calcium and / or calcium compound and phosphate and / or silicon oxide (b) molybdate (c) triazoles, thiols, thiadiazoles,
One or more organic compounds selected from thiazoles and thiurams 10. The method according to claim 1, wherein the organic resin film contains a solid lubricant.
The organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment according to 7, 8, or 9. 11. 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. 2,3,4,5,6,
The organic-coated steel sheet having excellent corrosion resistance in a high-temperature and high-humidity environment according to 7, 8, 9 or 10.