JP5031420B2 - Surface-treated steel sheet with excellent corrosion resistance, electrical conductivity, and abrasion resistance - Google Patents

Description

  The present invention relates to a surface-treated steel sheet that is optimal for applications such as automobiles, home appliances, and building materials, and particularly relates to an environmentally-friendly surface-treated steel sheet that does not contain any pollution-controlling substances such as hexavalent chromium in the film.

  Conventionally, for steel sheets for automobiles, steel sheets for household appliances, and steel sheets for building materials, hexavalent chromium is used for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of zinc-plated steel sheets or aluminum-based plated steel sheets. Steel plates that have been subjected to chromate treatment with a treatment liquid containing as a main component have been widely used. However, since chromate treatment uses hexavalent chromium, which is a pollution-controlling substance, recently there has been a movement to regulate its use. On the other hand, instead of chromate treatment, surface treatment technology that does not use hexavalent chromium at all is used. Development is actively underway. Among these, several techniques using an organic compound or an organic resin have been proposed, and examples include the following.

(1) Technology for forming a film from an aqueous resin composition obtained by reacting an epoxy resin with a hydrazine derivative having active hydrogen, a surface treatment composition containing a silane coupling agent, phosphoric acid, and the like (for example, Patent Document 1)
(2) A resin composition in which a composite oxide film containing fine oxide particles, phosphoric acid and a specific metal is formed as a lower layer, and an hydrazine derivative having active hydrogen is reacted with an organic resin such as an epoxy resin on the upper layer. Of forming an organic film with a coating composition containing a rust preventive additive and a specific anticorrosive additive (for example, Patent Document 2)
In order to improve the curability of the epoxy resin constituting the organic film, the following techniques have been proposed.
(3) Technology for introducing a basic nitrogen atom and a primary hydroxyl group at the end of an epoxy resin (for example, Patent Document 3)

  In particular, in the field of home appliances in recent years, there are an increasing number of cases in which steel plates are used without coating for the purpose of saving process and cost. In such a usage pattern, in order to satisfy various performance requirements regarding the surface appearance, a coated metal plate in which an organic composite film based on a special resin is formed on a steel plate has been developed. The surface-treated steel sheet with such an organic composite film may cause abrasion due to rubbing with corrugated cardboard or the like during product transportation. Significantly reduce the commercial value.

In order to improve the abrasion resistance, the following techniques have been proposed.
(4) Technology for melting the lubricant simultaneously with the baking of the film and protecting the film surface with the lubricant (for example, Patent Document 4)
(5) Technology for projecting a lubricant on the surface of the film and using the lubricant as a spacer (for example, Patent Documents 5 and 6)
JP 2003-105554 A JP 2002-53979 A JP-A-7-118870 JP 2001-288484 A JP 2002-212749 A JP-A-8-207199

However, these conventional techniques have the following problems.
First, in the techniques (1) and (2), a dense organic polymer film (barrier layer) is formed by imparting a hydrazine derivative to an epoxy resin, thereby imparting desired corrosion resistance. Further, the barrier property is enhanced by crosslinking using a curing agent such as polyisocyanate. However, since the hydroxyl group of the epoxy resin that crosslinks with the curing agent is a secondary hydroxyl group, a sufficient crosslinking density cannot be obtained due to steric hindrance with the resin skeleton, and the corrosion resistance is insufficient.

On the other hand, in the technique (3), the terminal epoxy group is modified with alkanolamine to introduce a basic nitrogen atom and a primary hydroxyl group, thereby improving the adhesion and curability of the epoxy resin. However, the organic film formed by such a technique does not sufficiently exhibit the adhesion due to the basic nitrogen atom of the alkanolamine in the chromium-free film, and the corrosion resistance is insufficient.
In addition, since the technologies (4) and (5) provide abrasion resistance with a specific lubricant, applicable lubricants are limited, and it is difficult to design lubrication characteristics required during processing. is there.

  Accordingly, an object of the present invention is to solve such problems of the prior art, and to obtain excellent corrosion resistance without containing a pollution control substance such as hexavalent chromium in the film, and also relates to the type of lubricant to be applied. Another object of the present invention is to provide a surface-treated steel sheet that has excellent abrasion resistance and excellent electrical conductivity.

As a result of intensive studies by the present inventors in order to solve the above-described problems, the epoxy resin (A) having a primary hydroxyl group in the resin is crosslinked with the hydroxyl group on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet. It has been found that remarkably excellent corrosion resistance and abrasion resistance can be obtained by forming an organic film by a coating composition containing a curing agent (B) having a group and a solid lubricant (C).
The present invention has been made on the basis of such knowledge and has the following gist.

（式中、Ｒ＝ＨまたはＣＨ_３、ｎは３〜６）
水酸基と架橋する基を有する硬化剤（Ｂ）と、固形潤滑剤（Ｃ）を含有し、エポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分質量比（Ａ）／（Ｂ）が９５／５〜５５／４５、固形潤滑剤（Ｃ）の配合量がエポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分の合計１００質量部に対して１〜８０質量部である塗料組成物を塗布し、乾燥することにより形成された皮膜厚が０．１〜５μｍの有機皮膜を有することを特徴とする耐食性、導電性および耐アブレージョン性に優れた表面処理鋼板。 [1] An epoxy resin (a1) and a cyclic ester compound (a2) represented by the following formula (2) are added to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet [mol number of epoxy resin (a1)] / [ Epoxy resin (A) having a primary hydroxyl group in the resin, obtained by reacting under conditions of cyclic ester compound (a2)] = 0.05 to 0.5 ,

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by having an organic film having a film thickness of 0.1 to 5 μm formed by drying.

（式中、Ｒ＝ＨまたはＣＨ_３、ｎは３〜６）
水酸基と架橋する基を有する硬化剤（Ｂ）と、固形潤滑剤（Ｃ）を含有し、エポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分質量比（Ａ）／（Ｂ）が９５／５〜５５／４５、固形潤滑剤（Ｃ）の配合量がエポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分の合計１００質量部に対して１〜８０質量部である塗料組成物を塗布し、乾燥することにより形成された皮膜厚が０．１〜５μｍの有機皮膜を有することを特徴とする耐食性、導電性および耐アブレージョン性に優れた表面処理鋼板。 [2] It has a lower layer coating not containing chromium on the surface of a zinc-based plated steel plate or an aluminum-based plated steel plate, and an epoxy resin (a1) and a cyclic ester compound (a2) represented by the following formula (2) on the upper layer Epoxy having a primary hydroxyl group in the resin, obtained by reacting the resin under the conditions of [number of moles of epoxy resin (a1)] / [number of moles of cyclic ester compound (a2)] = 0.05 to 0.5 Resin (A);

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by having an organic film having a film thickness of 0.1 to 5 μm formed by drying.

[3] In the surface-treated steel sheet according to [2], the lower layer film is selected from (α) silica, (β) phosphoric acid and / or a phosphoric acid compound, and (γ) Mg, Mn, and Al. It contains at least one kind of metal (including the case where it is included as a compound and / or a composite compound) and (σ) a tetravalent vanadium compound, and the adhesion amount of each of these components is
(Α) Silica: ₁ to 2000 mg / m ^{2 in} terms of SiO ²
(Β) Phosphoric acid and / or phosphoric acid compound: 1 to 1000 mg / m ^{2 in} total in terms of P
(Γ) One or more metals selected from Mg, Mn, and Al: 0.5 to 800 mg / m ^{2 in} total in terms of Mg, Mn, and Al
(Σ) Tetravalent vanadium compound: 0.1 to 50 mg / m ^{2 in} terms of V
A surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by being

[4] In the surface-treated steel sheet according to any one of [1] to [3], the epoxy resin (A) is an epoxy resin in which an epoxy group is modified with an active hydrogen-containing compound, and the active hydrogen-containing compound is A surface-treated steel sheet excellent in corrosion resistance, electrical conductivity, and abrasion resistance, characterized in that a part or all thereof is a hydrazine derivative having active hydrogen.
[5] In the surface-treated steel sheet according to any one of the above [1] to [4], the coating composition for forming an organic film is further one or more types of prevention selected from the following (a) to (e): Corrosion resistance, conductivity and abrasion resistance characterized by containing 1 to 100 parts by mass of the rust additive component (D) with respect to a total of 100 parts by mass of the solid content of the epoxy resin (A) and the curing agent (B). Excellent surface-treated steel sheet.
(A) Phosphate (b) Ca ion exchange silica (c) Molybdate (d) Silicon oxide (e) One or more selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams Organic compounds

（式中、Ｒ＝ＨまたはＣＨ_３、ｎは３〜６）
水酸基と架橋する基を有する硬化剤（Ｂ）と、固形潤滑剤（Ｃ）を含有し、エポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分質量比（Ａ）／（Ｂ）が９５／５〜５５／４５、固形潤滑剤（Ｃ）の配合量がエポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分の合計１００質量部に対して１〜８０質量部である塗料組成物を塗布し、５０〜３５０℃の到達板温で加熱乾燥することにより、皮膜厚が０．１〜５μｍの有機皮膜を形成することを特徴とする耐食性、導電性および耐アブレージョン性に優れた表面処理鋼板の製造方法。 [6] An epoxy resin (a1) and a cyclic ester compound (a2) represented by the following formula (2) are added to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet [number of moles of epoxy resin (a1)] / [ Epoxy resin (A) having a primary hydroxyl group in the resin, obtained by reacting under conditions of cyclic ester compound (a2)] = 0.05 to 0.5 ,

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by forming an organic film having a film thickness of 0.1 to 5 μm by heating and drying at an ultimate plate temperature of 50 to 350 ° C. Manufacturing method.

（式中、Ｒ＝ＨまたはＣＨ_３、ｎは３〜６）
水酸基と架橋する基を有する硬化剤（Ｂ）と、固形潤滑剤（Ｃ）を含有し、エポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分質量比（Ａ）／（Ｂ）が９５／５〜５５／４５、固形潤滑剤（Ｃ）の配合量がエポキシ樹脂（Ａ）と硬化剤（Ｂ）の固形分の合計１００質量部に対して１〜８０質量部である塗料組成物を塗布し、５０〜３００℃の到達板温で加熱乾燥することにより、皮膜厚が０．１〜５μｍの有機皮膜を形成することを特徴とする耐食性、導電性および耐アブレージョン性に優れた表面処理鋼板の製造方法。 [7] A lower layer film not containing chromium is formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, and then the epoxy resin (a1) and the cyclic ester represented by the following formula (2) are formed on the surface of the lower layer film. The compound (a2) is first grade in the resin obtained by reacting the compound (a2) under the condition of [number of moles of epoxy resin (a1)] / [number of moles of cyclic ester compound (a2)] = 0.05 to 0.5. An epoxy resin (A) having a hydroxyl group;

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by forming an organic film having a film thickness of 0.1 to 5 μm by heating and drying at an ultimate plate temperature of 50 to 300 ° C. Manufacturing method.

  The surface-treated steel sheet of the present invention provides excellent corrosion resistance without containing pollution control substances such as hexavalent chromium in the film, and excellent abrasion resistance regardless of the type of lubricant to be applied. Moreover, it is excellent also in electroconductivity.

The details of the present invention and the reasons for limitation will be described below.
Examples of the zinc-based plated steel sheet used as the base of the surface-treated steel sheet of the present invention include a galvanized steel sheet, a Zn-Ni alloy-plated steel sheet, a Zn-Fe alloy-plated steel sheet (electroplated steel sheet, galvannealed steel sheet), Zn-Cr. Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-Co alloy-plated steel sheet, Zn-Co-Cr alloy-plated steel sheet, Zn-Cr-Ni alloy-plated steel sheet, Zn-Cr-Fe alloy-plated steel sheet, Zn-Al alloy plating Steel plate (for example, Zn-5% Al alloy-plated steel plate, Zn-55% Al alloy-plated steel plate), Zn-Mg alloy-plated steel plate, Zn-Al-Mg alloy-plated steel plate (for example, Zn-6% Al-3% Mg) Alloy-plated steel sheets, Zn-11% Al-3% Mg alloy-plated steel sheets), and metal oxides, polymers, etc. are dispersed in the plating film of these plated steel sheets Zinc-based composite-plated steel sheet (for example, Zn-SiO ₂ dispersion plating steel plate) was the like can be used.

In addition, among the above-described plating, a multi-layer plated steel sheet in which two or more layers of the same type or different types are plated can also be used.
Moreover, as an aluminum system plated steel plate used as the base of the surface treatment steel plate of this invention, an aluminum plating steel plate, an Al-Si alloy plating steel plate, etc. can be used.
Moreover, as a plated steel plate, the steel plate surface may be plated in advance with thinning such as Ni, and the above-described various plating may be performed thereon.
As a plating method, any feasible method such as an electrolytic method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, or a gas phase method may be employed.

  In addition, in order to prevent film defects and unevenness when a two-layer film as described later is formed on the plating film surface, 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, in order to prevent blackening (a kind of oxidation phenomenon on the plating surface) under the usage environment of the surface-treated 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 selected from the above can also be performed. In addition, when an electrogalvanized steel sheet is used as the base steel sheet, iron group metal ions (one or more selected from Ni ions, Co ions, and Fe ions) are added to the electroplating bath for the purpose of preventing blackening. In addition, 1 ppm or more of these metals can be contained in the plating film. In this case, there is no particular limitation on the upper limit of the iron group metal concentration in the plating film.

Next, the organic film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet and the coating composition for forming the film will be described.
In the surface-treated steel sheet of the present invention, the organic coating formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is an epoxy resin (A) having a primary hydroxyl group in the resin and a curing agent having a group that crosslinks with the hydroxyl group. It is a film formed by applying a coating composition containing (B) and the solid lubricant (C) and drying. This organic film does not contain any chromium.

上記化学構造式中、ｑは０〜５０の整数、好ましくは１〜４０の整数、特に好ましくは２〜２０の整数である。 The epoxy resin (A) constituting the coating composition for film formation is not particularly limited as long as it has a primary hydroxyl group in the resin. Such an epoxy resin (A) can be obtained, for example, by reacting the cyclic ester compound (a2) with the epoxy resin (a1).
The epoxy resin (a1) has a number average molecular weight of 1500 to 50000, preferably 2000 to 4000, which is obtained by reacting a polyphenol such as bisphenol A or bisphenol F with an epihalohydrin such as epichlorohydrin to introduce an epoxy group. A bisphenol type epoxy resin having an equivalent weight of 750 to 7500, preferably 2000 to 5000 is preferable. From the viewpoint of the corrosion resistance of the organic film obtained, an epoxy of the following formula (1) which is a reaction product of bisphenol A and epihalohydrin is used. Resins are particularly preferred.

In said chemical structural formula, q is an integer of 0-50, Preferably it is an integer of 1-40, Most preferably, it is an integer of 2-20.

  Examples of commercially available products of the epoxy resin (a1) include jER828 (epoxy equivalent of about 190, number average molecular weight of about 350), jER834 (epoxy equivalent of about 250, number average molecular weight of about 470), jER1004 manufactured by Japan Epoxy Resin Co., Ltd. (Epoxy equivalent of about 950, number average molecular weight of about 1600), jER1007 (epoxy equivalent of about 2250, number average molecular weight of about 2900), jER1009 (epoxy equivalent of about 3250, number average molecular weight of about 3750), jER1010 (epoxy equivalent of about 4000, number average) Molecular weight of about 5500), Araldite AER6099 (epoxy equivalent of about 3500, number average molecular weight of about 3800) manufactured by Asahi Ciba, Epoxy R-309 (epoxy equivalent of about 3500, number average molecular weight of about 3800) manufactured by Mitsui Chemicals, Inc. Can be listed , All trade names).

（式中、Ｒ＝ＨまたはＣＨ_３、ｎは３〜６）
具体的には、δ−バレロラクトン、ε−カプロラクトン、ζ−エナラクトン、η−カプリロラクトン、γ−バレロラクトン、δ−カプロラクトン、ε−エナラクトン、ξ−カプリロラクトンなどが挙げられ、これらの１種または２種以上を用いることができる。また、これらのなかでも特に好ましいのは、ε−カプロラクトンである。
上記付加反応において、式（２）の環状エステル化合物（ａ２）は開環し、エポキシ樹脂（ａ１）中の二級水酸基と反応し、一級水酸基を付与することができる。 The cyclic ester compound (a2) mentioned as an example of a compound that introduces a primary hydroxyl group by reacting with the epoxy resin (a1) is represented by the following formula (2).

(In the formula, R = H or CH ₃ , n is 3 to 6)
Specific examples include δ-valerolactone, ε-caprolactone, ζ-enalactone, η-caprolactone, γ-valerolactone, δ-caprolactone, ε-enalactone, ξ-caprolactone, and the like. Species or two or more can be used. Of these, ε-caprolactone is particularly preferable.
In the above addition reaction, the cyclic ester compound (a2) of the formula (2) can open a ring and react with the secondary hydroxyl group in the epoxy resin (a1) to give a primary hydroxyl group.

Moreover, the terminal of the epoxy resin having a primary hydroxyl group may be an epoxy group, but it can be obtained by modifying a part or all of the compound with an active hydrogen-containing compound which is a hydrazine derivative (a3) having active hydrogen. The corrosion resistance and conductivity of the film can be greatly improved.
Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy resin include those shown below, and one or more of these can be used, but at least a part of the active hydrogen-containing compound (preferably Are all hydrazine derivatives (a3) having active hydrogen.
・ Hydrazine derivatives with active hydrogen ・ Primary or secondary amine compounds with active hydrogen ・ Organic acids such as ammonia and carboxylic acids ・ Halogen halides such as hydrogen chloride ・ Alcohols and thiols ・ Having active hydrogen Quaternary chlorinating agent which is a mixture of hydrazine derivative or tertiary amine and acid

Specific examples of the hydrazine derivative (a3) 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, aminopolyacrylamide Hydrazide compounds such as;
(2) pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;
(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;

(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;
Among 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.

The reaction product of the epoxy resin (a1) and the cyclic ester compound (a2) is obtained by converting the epoxy resin (a1) and the cyclic ester compound (a2) at a temperature of 100 to 200 ° C., preferably 140 to 180 ° C. for 1 to 6 hours. It can obtain by making it react and the epoxy resin ( _A0 ) which has a primary hydroxyl group as a reaction material is obtained. Furthermore, when the hydrazine derivative (a3) having active hydrogen is reacted, 40 parts of the active hydrogen-containing compound, which is a hydrazine derivative (a3) in which a part or all of the compounds are active hydrogen, is reacted with the epoxy resin (A ₀ ). The reaction is carried out at a temperature of ˜200 ° C., preferably 80 ° C. to 130 ° C. for about 1 to 8 hours.

The blending ratio of the epoxy resin (a1), the cyclic ester compound (a2) and the hydrazine derivative (a3) having active hydrogen is preferably 5 to 20 mol% of the epoxy resin (a1) with respect to the total number of moles. More preferably 7 to 20 mol%, cyclic ester compound (a2) is preferably 40 to 90 mol%, more preferably 40 to 80 mol%, hydrazine derivative (a3) is preferably 0 to 40 mol%, more preferably It is suitable to set it as the range of 15-40 mol%. This is because the hydrazine derivative and the primary hydroxyl group in the resin skeleton are made to have an appropriate composition to balance corrosion resistance and reactivity.
In the production of the epoxy resin (A ₀ ), in particular, [number of moles of epoxy resin (a1)] / [number of moles of cyclic ester compound (a2)] = 0.05 to 0.5, preferably 0.1 to A range of 0.5, more preferably 0.1 to 0.25 provides a good balance between coating film hardness and reactivity, and a balance between corrosion resistance and reactivity.

  The above 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 hydroxyl groups; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons etc. Illustration can, it is possible to use one or more of these. Of these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin and film-forming properties.

  In order to form a dense barrier film on the specific epoxy resin (A) as described above, a curing agent (B) having a group that crosslinks with a hydroxyl group is blended, and the film is heated and cured. The curing method for forming a film with the resin composition was selected from (1) a curing method using a urethanization reaction between isocyanate and a hydroxyl group in the base resin, and (2) melamine, urea and benzoguanamine. Etherification reaction between an alkyl etherified amino resin obtained by reacting one or more methylol compounds obtained by reacting formaldehyde with one or more monovalent alcohols having 1 to 5 carbon atoms and a hydroxyl group in the base resin. Among these, the curing method (1) is more preferable because it can form a dense film.

The polyisocyanate compound as a curing agent that can be used in the curing method (1) is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule. Or a compound obtained by partially reacting these compounds with a polyhydric alcohol. Examples of such polyisocyanate compounds include the following.
(I) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate (ii) above (i) Or a mixture thereof and a polyhydric alcohol (dihydric alcohols such as ethylene glycol and propylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol; sorbitol, dipentaerythritol, etc. A compound of at least two isocyanates in one molecule. These polyisocyanate compounds may be used alone or in combination of two or more. It can be.

Moreover, as a protective agent (blocking agent) of a polyisocyanate compound, for example,
(1) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol, octyl alcohol;
(2) ethylene glycol and / or diethylene glycol monoethers, for example, monoethers such as methyl, ethyl, propyl (n-, iso), butyl (n-, iso, sec);
(3) Aromatic alcohols such as phenol and cresol;
(4) oximes such as acetooxime and methyl ethyl ketone oxime;
A polyisocyanate compound that is stably protected at least at room temperature can be obtained by reacting one or more of these with the polyisocyanate compound.

  The mixing ratio of the curing agent (B) is 95/5 to 55/45, preferably 90/10 to 65/35, in terms of the mass ratio (A) / (B) of the solid content with the epoxy resin (A). If the amount of the curing agent (B) is too large, the performance of the film tends to deteriorate. For example, when a polyisocyanate compound is used as a curing agent, the polyisocyanate compound has water absorption, and if the blending amount is too large, the adhesion of the organic film is deteriorated. Furthermore, the unreacted polyisocyanate compound moves into the upper layer film such as electrodeposition coating, thereby causing an inhibition of curing of the upper layer film and poor adhesion.

The epoxy resin is sufficiently crosslinked by the addition of the crosslinking agent (curing agent) as described above, but it is desirable to use a known curing accelerating catalyst in order to further increase the low temperature crosslinking property. Examples of the curing accelerating catalyst include N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, and bismuth nitrate.
For the purpose of slightly improving physical properties such as adhesion, a known resin such as acrylic, alkyd, or polyester can be mixed and used together with an epoxy resin. The mixing amount is 100 parts by mass or less, preferably 50 parts by mass or less with respect to 100 parts by mass of the solid content of the epoxy resin (A). When the mixing amount exceeds 100 parts by mass, the performance such as corrosion resistance tends to deteriorate.

  In order to further improve the abrasion resistance of the organic film, a solid lubricant (C) is blended in the organic film (coating composition for film formation). In the present invention, the means for imparting abrasion resistance to the film is not a specific solid lubricant as in the prior art described above, but by a crosslinking reaction between the primary hydroxyl group of the epoxy resin (A) and the curing agent (B). It is to form a dense and strong film to be generated. Therefore, the solid lubricant that can be used in the present invention is not particularly limited, and known ones can be applied. Examples thereof 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) Fluororesin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.) In addition to these, fatty acid amide compounds (for example, stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, oleic acid amide, esyl) Acid amides, alkylene bis-fatty acid amides), metal soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate), metal sulfides (eg, molybdenum disulfide, tungsten disulfide, etc.) Etc.), graphite, fluorinated graphite, boron nitride, polyalkylene glycols may be used alone or in combinations of two or more such alkali metal sulfate.

Among the above solid lubricants, polyethylene wax and fluororesin fine particles (in particular, polytetrafluoroethylene resin fine particles) are preferable.
Examples of the polyethylene wax include Hoechst's Selidust 9615A, Selidust 3715, Selidust 3620, Selidust 3910 (all are trade names), Sanyo Chemical Co., Ltd. Sun Wax 131-P, Sun Wax 161-P ( As described above, all are trade names), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (all are trade names) manufactured by Mitsui Chemicals, Inc. are used. be able to.

The fluororesin fine particles are most preferably tetrafluoroethylene fine particles. For example, Lubron L-2 and Lubron L-5 (all are trade names) manufactured by Daikin Industries, Ltd., Mitsui DuPont Co., Ltd. MP1100, MP1200 (all are trade names), full-on dispersion AD1, full-on dispersion AD2, full-on L141J, full-on L150J, full-on L155J (all are trade names) manufactured by Asahi IC Fluoropolymers Co., Ltd. Is preferred.
Among these, a particularly excellent lubricating effect can be expected by the combined use of polyolefin wax and tetrafluoroethylene fine particles.
The blending amount of the solid lubricant (C) is 1 to 80 parts by mass, preferably 3 to 40 in terms of the solid content with respect to 100 parts by mass of the total solids of the epoxy resin (A) and the curing agent (B). Mass parts. When the blending amount of the solid lubricant (C) is less than 1 part by mass, the lubricating effect is poor. On the other hand, when the blending amount exceeds 80 parts by mass, the paintability is unfavorable.

The organic film (coating composition for forming a film) is preferably further blended with one or more rust preventive additives (D) selected from the following (a) to (e).
(A) Phosphate (b) Ca ion exchange silica (c) Molybdate (d) Silicon oxide (e) One or more selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams Organic compounds

The phosphate which is the said component (a) contains all kinds of salts, such as a single salt and a double salt. Moreover, there is no restriction | limiting in particular in the metal cation which comprises it, Any metal cations, such as zinc phosphate, magnesium phosphate, calcium phosphate, and 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. In addition, orthophosphate may be polyphosphate other than orthophosphate. Includes all condensed phosphates such as salts.
Moreover, corrosion resistance can further be improved by adding a calcium compound together with the phosphate which is the said component (a). The calcium compound may be any of calcium oxide, calcium hydroxide, and calcium salt, and one or more of these 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, and calcium phosphate, calcium and calcium such as calcium phosphate / zinc, calcium phosphate / magnesium, etc. Double salts containing other cations may be used.

Moreover, the Ca ion exchange silica which is said component (b) is what fixed the calcium ion on the surface of the porous silica gel powder, Ca ion is discharge | released in a corrosive environment, and forms a precipitation film | membrane.
Any Ca ion-exchanged silica can be used, but those having an average particle size of 6 μm or less, preferably 4 μm or less are preferable, and for example, those having an average particle size of 2 to 4 μm can be used. When the average particle size of the Ca ion exchange silica exceeds 6 μm, the corrosion resistance is lowered and the dispersion stability in the coating composition is lowered.
The Ca concentration in the Ca ion exchange silica is preferably 1 mass% or more, and preferably 2 to 8 mass%. If the Ca concentration is less than 1 mass%, the rust prevention effect due to Ca release cannot be sufficiently obtained. The surface area, pH, and oil absorption amount of the Ca ion exchange silica are not particularly limited.

Examples of the Ca ion exchange silica as described above include WR Grace & Co. SHIELDEX C303 (average particle size 2.5 to 3.5 μm, Ca concentration 3 mass%), SHIELDEX AC3 (average particle size 2.3 to 3.1 μm, Ca concentration 6 mass%), SHIELDEX AC5 (average particle size 3. 8 to 5.2 μm, Ca concentration 6 mass% (all are trade names), SHIELDEX (average particle diameter 3 μm, Ca concentration 6 to 8 mass%) manufactured by Fuji Silysia Chemical Ltd., SHIELDEX SY710 (average particle diameter 2) 0.2 to 2.5 μm, Ca concentration of 6.6 to 7.5 mass%) (all are trade names) and the like can be used.
The molybdate that is the component (c) 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 phosphomolybdate etc. are mentioned as a double salt.

  The silicon oxide as the component (d) may be either colloidal silica or dry 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 manufactured by Nissan Chemical Industries, Ltd. , Snowtex S (above, all are trade names), Cataloid S, Cataloid SI-350, Cataloid SI-40, Cataloid SA, Cataloid SN (above, all are trade names) manufactured by Catalytic Kasei Kogyo Co., Ltd., Asahi Denka Adelite AT-20-50 manufactured by Kogyo Co., Ltd., Adelite AT-20N, Adelite AT-300, Adelite AT-300S, Adelite AT20Q (all are trade names) and the like can be used.

In addition, when the 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, organosilica sol E-ST manufactured by Nissan Chemical Industries, Ltd. -ZL, organosilica sol NPC-ST, organosilica sol DMAC-ST, organosilica sol DMAC-ST-ZL, organosilica sol XBA-ST, organosilica sol MIBK-ST (all are trade names), manufactured by Catalyst Kasei Kogyo Co., Ltd. OSCAL-1132, OSCAL-1232, OSCAL-1332, OSCAL-1432, OSCAL-1532, OSCAL-1632, OSCAL-1722 (all of which are trade names) can be used.
In particular, the organic solvent-dispersed silica sol is excellent in dispersibility and superior in corrosion resistance than fumed silica.

Examples of the fumed silica include AEROSIL R971, AEROSIL R812, AEROSIL R811, AEROSIL R974, AEROSIL R202, AEROSIL R805, AEROSIL 130, AEROSIL 200, AEROSIL 300, and more from AEROSIL 300CF manufactured by Nippon Aerosil Co., Ltd. Can also be used.
The fine-particle silica contributes to the formation of a dense and stable zinc corrosion product in a corrosive environment, and the corrosion product is considered to be able to suppress the promotion of corrosion by being densely formed on the plating surface. It has been.
From the viewpoint of corrosion resistance, it is preferable to use fine silica particles having a particle diameter of 5 to 50 nm, desirably 5 to 20 nm, more preferably 5 to 15 nm.

  Among the organic compounds of the component (e), triazoles include 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5- Amino-3-mercapto-1,2,4-triazole, 1H-benzotriazole, etc., and thiols include 1,3,5-triazine-2,4,6-trithiol, 2-mercaptobenzimidazole, etc. The thiadiazoles include 5-amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, and the thiazoles include 2-N, N -Diethylthiobenzothiazole, 2-mercaptobenzothiazole, etc., and thiurams include tetraethylthiuramdisulfur Such as soil, and the like, respectively.

  The blending amount of the rust preventive additive component (D) (the total blending amount of one or more self-repairing substances selected from the components (a) to (e)) is the epoxy resin (A) and the curing agent. It is appropriate that the total solid content of (B) is 1 to 100 parts by mass, preferably 5 to 80 parts by mass, and more preferably 10 to 50 parts by mass in terms of the solid content. If the compounding amount of the rust preventive additive (D) is less than 1 part by mass, the effect of improving the corrosion resistance is small. On the other hand, if the compounding amount exceeds 100 parts by mass, the corrosion resistance decreases, which is not preferable.

  In addition to the above rust preventive additives, other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide) may be used as a corrosion inhibitor in the organic film (coating composition for film formation). , Antimony oxide, etc.), phosphomolybdate (eg, aluminum phosphomolybdate), organic phosphoric acid and its salts (eg, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts thereof, alkali One or more of metal salts, alkaline earth metal salts, etc.), organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.) can be added.

In the organic film (coating composition for film formation), if necessary, as an additive, an organic coloring pigment (for example, a condensed polycyclic organic pigment, a phthalocyanine organic pigment), a coloring dye (for example, Organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.), inorganic pigments (eg, titanium oxide), chelating agents (eg, thiols), conductive pigments (eg, zinc, aluminum, nickel, etc.) , Iron phosphide, antimony-doped tin oxide, etc.), coupling agents (for example, silane coupling agents, titanium coupling agents, etc.), melamine / cyanuric acid adducts, etc. it can.
The film thickness of the organic film is 0.1 to 5 μm, preferably 0.2 to 2 μm. If the film thickness is less than 0.1 μm, sufficient corrosion resistance cannot be obtained, while if it exceeds 5 μm, the conductivity is lowered.

In order to produce the surface-treated steel sheet as described above, a coating composition for forming an organic film containing the above-described components is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and dried.
Arbitrary methods, such as a coating method, a dipping method, a spray method, can be employ | adopted as a method of coating the coating composition for organic film formation on the plated steel plate surface. As a coating method, any method such as a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, or a die coater may be used. In addition, after the coating process, dipping process or spraying process using a squeeze coater or the like, the coating 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.

  After application of the coating composition, drying is usually carried out without washing with water, but a washing step may be carried out after application of the coating composition. For the heat drying treatment, a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace, or the like can be used, but a high frequency induction heating furnace is particularly preferable from the viewpoint of corrosion resistance. The heat treatment is desirably performed in the range of 50 to 350 ° C., preferably 80 to 250 ° C., at the ultimate plate temperature. If the heating temperature is less than 50 ° C., a large amount of the solvent remains in the film, resulting in insufficient corrosion resistance. Further, when the heating temperature exceeds 350 ° C., not only is it uneconomical, but there is a possibility that defects occur in the film and the corrosion resistance is lowered.

In the lower layer of the organic film described above, a lower film that does not contain chromium can be formed as necessary. That is, this surface-treated steel sheet has a lower layer film not containing chromium on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and an epoxy resin (A) having a primary hydroxyl group in the resin as an upper layer thereof. And a coating composition containing a curing agent (B) having a crosslinkable group and a solid lubricant (C), and an organic film formed by drying.
The lower layer film is not particularly limited as long as it is a rust-free film that does not contain chromium, and a known rust-proof film can be applied. Corrosion resistance is obtained.

This undercoat is
(Α) silica,
(Β) phosphoric acid and / or a phosphoric acid compound;
(Γ) one or more metals selected from Mg, Mn, and Al (including the case where they are included as a compound and / or a composite compound);
(Σ) a tetravalent vanadium compound;
A composite oxide film containing these as a main component, and by including these four components, a specific antirust effect as described later can be obtained.

The silica as the component (α) is particularly preferably colloidal silica from the viewpoint of corrosion resistance. Of these, particles having a particle size of 14 nm or less, more preferably 8 nm or less are preferred from the viewpoint of corrosion resistance. Moreover, what dispersed the dry-type silica fine particle in the membrane | film | coat composition solution can also be used, A particle diameter is 12 nm or less especially, The thing of 7 nm or less is more preferable.
The adhesion amount of the component (α) in the film is preferably 1 to 2000 mg / m ^{2 in} terms of SiO ₂ . If the adhesion amount in terms of SiO ₂ is less than 1 mg / m ² , the effect due to the addition of the component (α) cannot be sufficiently expected. On the other hand, if it exceeds 2000 mg / m ² , problems may occur in adhesion and blackening. . From such a viewpoint, the more preferable adhesion amount is 5 to 1000 mg / m ² , and particularly preferably 10 to 200 mg / m ² .

As the phosphoric acid and / or phosphoric acid compound as the component (β), for example, one type or two or more types of orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metal salts and compounds thereof are added to the coating composition. Therefore, it can mix | blend as a film | membrane component.
There is no particular limitation on the form of the phosphate compound present in the film, and it may be crystal or non-crystalline. There are no particular restrictions on the ionicity and solubility of phosphoric acid and / or phosphoric acid compounds in the film.
The adhesion amount of the component (β) in the film is preferably 1 to 1000 mg / m ^{2 in} total in terms of P. If the adhesion amount in terms of P is less than 1 mg / m ² , the effect due to the addition of the component (β) cannot be sufficiently expected. On the other hand, if it exceeds 1000 mg / m ² , problems may occur in corrosion resistance and spot weldability. From this point of view, more preferred coating weight is 5 to 500 mg / ^{m 2,} particularly preferably 10-100 mg / ^{m 2.}

The form in which one or more kinds of metals selected from Mg, Mn, and Al as the component (γ) are present in the film is not particularly limited. As a metal, or as an oxide, hydroxide, or hydrated oxide Further, it may exist as a compound such as a phosphate compound or a coordination compound, or as a complex compound. There is no particular limitation on the ionicity and solubility of these compounds, hydroxides, hydrated oxides, phosphate compounds, coordination compounds, and the like.
As a method for introducing the component (γ) into the film, it may be contained in the film composition as Mg, Mn, Al phosphate, sulfate, nitrate, chloride or the like.
The adhesion amount of the component (γ) in the film is preferably 0.5 to 800 mg / m ^{2 in} terms of Mg, Mn, and Al. Mg, Mn, can not be effective enough expected due to the addition of component (gamma) in the coating weight is less than 0.5 mg / ^{m 2} in sum of Al in terms, whereas, corrosion resistance exceeding 800 mg / ^{m 2,} the coating appearance Problems may arise. From such a viewpoint, a more preferable adhesion amount is 1 to 500 mg / m ² , and particularly preferably 5 to 100 mg / m ² .

Examples of the tetravalent vanadium compound that is the above component (σ) include vanadium oxide, hydroxide, sulfide, sulfate, carbonate, halide, nitride, fluoride, carbide, cyanide (thiocyanide). And salts thereof. One of these may be used alone, or two or more thereof may be mixed and used. Moreover, as a tetravalent vanadium compound, it is preferable to use what reduced the pentavalent vanadium compound to the tetravalent previously using the reducing agent especially from a viewpoint of corrosion resistance and blackening resistance. In this case, the reducing agent used may be either inorganic or organic, but is more preferably organic.
Among the vanadium compounds, when a pentavalent vanadium compound is used, a uniform film cannot be formed because the treatment liquid stability is poor, and sufficient corrosion resistance cannot be obtained. Moreover, when a bivalent and trivalent vanadium compound is used, corrosion resistance is inferior. On the other hand, when a tetravalent vanadium compound is used, there is no such problem, and excellent corrosion resistance is obtained due to a synergistic effect with the components (α) to (γ).

The adhesion amount of the component (σ) in the film is preferably 0.1 to 50 mg / m ^{2 in} terms of V. If the adhesion amount in terms of V is less than 0.1 mg / m ² , the effect due to the addition of the component (σ) cannot be sufficiently expected. On the other hand, if it exceeds 50 mg / m ² , there is a risk of problems of coloring and blackening of the film. . From this point of view, more preferred coating weight is 0.5 to 30 mg / ^{m 2,} particularly preferably 1-10 mg / ^{m 2.}
The reason why extremely excellent corrosion resistance can be obtained by forming a composite oxide film containing the above components on the surface of the plated steel sheet is not necessarily clear, but is presumed to be due to the following mechanism.

That is, first, with regard to the function and effect as a barrier film, a high-level barrier effect can be obtained by the dense and hardly soluble composite oxide film blocking the corrosion factor. This is because (a) silica forms a stable and dense barrier film together with phosphoric acid or a phosphoric acid compound and the component (γ) metal, and (b) silicate ions in silica undergo basic chlorination in a corrosive environment. By promoting the formation of zinc and improving barrier properties, (c) by adding a tetravalent vanadium compound, a tetravalent vanadyl (IV) ion: VO ₂ ⁺ or its complex ion (for example, [VO (SO ₄ ) ₂ ] ^2- ) and phosphate ions form a sparingly soluble salt in the film, and this salt improves the barrier properties. (D) The tetravalent vanadium compound is different from the pentavalent vanadium compound. It is thought that it is possible to form a uniform film because of its excellent processing solution stability. In particular, the component (γ) metal and vanadium compound through a bond with phosphate ion or silica. Dense and sparingly soluble Film is formed, and the action of the (a) ~ (d) is by combined organically is believed that a high degree of barrier effect.

Furthermore, the complex oxide film has an excellent self-repair effect in addition to the above-described advanced barrier effect. This is because (A) when a defect occurs in the film, OH ions are generated by the cathode reaction and the interface becomes alkaline, so that the component (γ) precipitates as Me (OH) ₂ , and is dense and hardly soluble. (B) As described above, phosphoric acid or phosphoric acid compound contributes to improving the compactness of the complex oxide film as well as corrosive reaction at the film defect part. The zinc ion dissolved by the anodic reaction is captured by the phosphoric acid component and forms a precipitate product as a poorly soluble zinc phosphate compound. (C) The tetravalent vanadium compound is due to its oxidizing action. The vanadium compound itself is reduced, and a film in the form of oxide or hydroxide is formed on the surface of the plating layer, which is thought to be due to its self-repairing action. As for the fruits, in particular, a film is formed in which the metal of the component (γ) and the vanadium compound are incorporated through binding with phosphate ions or silica, and the actions (A) to (C) are organically It is considered that a high degree of self-repair effect can be obtained by combining them.
In addition to the above-mentioned advanced barrier effect and self-repair effect of the lower layer film, the primary hydroxyl group of the epoxy resin of the organic film and the phosphoric acid of the lower layer film are intimately bonded through hydrogen bonding, and the intrusion and diffusion of corrosion factors Therefore, extremely excellent corrosion resistance is realized.

In order to produce the surface-treated steel sheet as described above, the surface coating of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is applied with a treatment liquid for the lower layer film in which the components as described above are blended, dried, and then A coating composition for forming an organic film containing the components as described above is applied and dried.
As a method for coating the surface of the plated steel sheet with a coating solution for the lower layer coating, any of a coating method, a dipping method, and a spray method may be used. In the coating method, a roll coater (3-roll method, 2-roll method, etc.), squeeze coater, DAIKO Any coating means such as a filter may be used. In addition, after the coating process, dipping process, and spraying process using a squeeze coater, the coating 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. Although there is no special restriction | limiting in the temperature of a process liquid, Room temperature-about 60 degreeC is suitable. Below room temperature, equipment for cooling is required, which is uneconomical. On the other hand, when the temperature exceeds 60 ° C., the solvent tends to evaporate, making it difficult to manage the treatment liquid.

  After coating the treatment liquid as described above, it is usually heat-dried without washing with water, but the treatment liquid used in the present invention forms a poorly soluble salt by reaction with the base plating steel plate, so that it is washed with water after treatment. You may go. A method of heating and drying the coated treatment liquid is arbitrary, and for example, means such as a dryer, a hot air furnace, a high-frequency induction heating furnace, an infrared furnace can be used, but a high-frequency induction heating furnace is particularly preferable from the viewpoint of corrosion resistance. . This heat drying treatment is desirably performed in the range of 50 to 300 ° C., desirably 80 to 200 ° C., more desirably 80 to 160 ° C. at the ultimate plate temperature. If the heating and drying temperature is less than 50 ° C., a large amount of solvent remains in the film, resulting in insufficient corrosion resistance. On the other hand, when the heating and drying temperature exceeds 300 ° C., not only is it uneconomical, but defects are easily generated in the film, and the corrosion resistance is lowered.

The present invention includes a steel plate having a coating as described above on both sides or one side. Accordingly, examples of the form of the steel sheet of the present invention include the following.
(1) One side: plating film-lower layer film-organic film, one side: plating film (2) One side: plating film-lower layer film-organic film, one side: plating film-known phosphate treatment film, etc. (3) Both sides: Plating film-Underlayer film-Organic film (4) Single side: Plating film-Underlayer film-Organic film, Single side: Plating film-Underlayer film (5) Single side: Plating film-Underlayer film-Organic film, Single side: Plating film-Organic film (6) One side: plating film-organic film, one side: plating film-organic film

For forming the lower layer film, a treatment liquid (aqueous solution) was prepared by appropriately blending the silica shown in Table 1, the phosphoric acid / phosphate compound shown in Table 2, the metal compound shown in Table 3, and the vanadium compound shown in Table 4.
For forming an organic film (upper layer film), the epoxy resin solutions R1 to R9 shown in Table 5 synthesized as follows, the curing agent shown in Table 6, the solid lubricant shown in Table 7, and the antirust additive shown in Table 8 A coating composition in which the components were appropriately blended was prepared.

[Synthesis Example 1] (equivalent to Invention Example)
In a reactor equipped with a thermometer, a stirrer and a heating device, 1448 parts by weight of epoxy resin “jER1007” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent of about 2250, number average molecular weight of about 2900) and 507 parts by weight of cyclohexanone were added. The mixture was heated to 140 ° C. and completely dissolved in 2 hours. Next, ε-caprolactone “PLACCEL
M ”(trade name, manufactured by Daicel) 73 parts by mass and 0.08 part by mass of dibutyltin oxide were added (solid content 75% during reaction), and the temperature was raised to 170 ° C. and reacted for 4 hours. Thereafter, 395 parts by mass of methyl isobutyl ketone, 371 parts by mass of cyclohexanone, and 585 parts by mass of an aromatic hydrocarbon solvent “Swazole 1500” (trade name, manufactured by Maruzen Petrochemical Co., Ltd.) were added, and an epoxy resin solution having a solid content of 35% R1 was obtained. Table 5 shows the molar ratio of epoxy resin / ε-caprolactone in this epoxy resin solution R1.

[Synthesis Example 2] (equivalent to Invention Example)
In a reactor equipped with a thermometer, a stirrer and a heating device, 1448 parts by weight of epoxy resin “jER1007” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent of about 2250, number average molecular weight of about 2900) and 507 parts by weight of cyclohexanone were added. The mixture was heated to 140 ° C. and completely dissolved in 2 hours. Next, ε-caprolactone “PLACCEL
M ”(trade name, manufactured by Daicel) 73 parts by mass and 0.08 part by mass of dibutyltin oxide were added (solid content 75% during reaction), and the temperature was raised to 170 ° C. and reacted for 4 hours. This was cooled to 80 ° C., and 44 parts by mass of methyl isobutyl ketone, 1024 parts by mass of butyl cellosolve and 54 parts by mass of 3-amino-1,2,4-triazole were added (solid content during reaction was 50%), and the epoxy group disappeared. The reaction was continued for about 6 hours. Thereafter, 395 parts of methyl isobutyl ketone, 371 parts by weight of cyclohexanone, 585 parts by weight of an aromatic hydrocarbon solvent “Swazole 1500” (trade name, manufactured by Maruzen Petrochemical Co., Ltd.) are added, and an epoxy resin solution R2 having a solid content of 35% is added. Got. Table 5 shows the molar ratio of epoxy resin / ε-caprolactone / 3-amino-1,2,4-triazole of this epoxy resin solution R2.

[Synthesis Examples 3 to 6] (equivalent to invention examples)
Epoxy resin solutions R3 to R5 and R6 were produced in the same manner as in Synthesis Example 1 by adjusting the amount of solvent so that the solid content was as shown in Table 5 and the solid content during the reaction was the same. As the epoxy resin, “jER1007” (trade name, manufactured by Japan Epoxy Resin, epoxy equivalent of about 2250, number average molecular weight of about 2900) is used in Synthesis Examples 3, 4, and 6, and “jER1009” (Product) is used in Synthesis Example 5. Name, manufactured by Japan Epoxy Resin, epoxy equivalent of about 3000, number average molecular weight of about 3750). Table 5 shows the molar ratio of epoxy resin / ε-caprolactone / 3-amino-1,2,4-triazole in the epoxy resin solutions R3 to R6.

[Synthesis Example 7] (equivalent to Comparative Example)
In a reactor equipped with a thermometer, a stirrer, and a heating device, 1518 parts by mass of epoxy resin “jER1007” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent of about 2250, number average molecular weight of about 2900) and 878 parts by mass of cyclohexanone were added. The mixture was heated to 140 ° C. and completely dissolved in 2 hours. This was cooled to 80 ° C., 411 parts by mass of methyl isobutyl ketone and 57 parts by mass of 3-amino-1,2,4-triazole were added, and the reaction was continued for about 6 hours until the epoxy group disappeared. Thereafter, 28 parts by mass of methyl isobutyl ketone, 1023 parts by mass of butyl cellosolve, 585 parts by mass of an aromatic hydrocarbon solvent “Swazole 1500” (trade name, manufactured by Maruzen Petrochemical Co., Ltd.) are added, and an epoxy resin solution having a solid content of 35% R7 was obtained. Table 5 shows the molar ratio of epoxy resin / 3-amino-1,2,4-triazole of this epoxy resin solution R7.

[Synthesis Example 8] (equivalent to Comparative Example)
The amount of the solid content shown in Table 5 was adjusted, and the amount of the solvent was adjusted so that the solid content during the reaction was the same, and an epoxy resin solution R8 was produced in the same manner as in Synthesis Example 7. As the epoxy resin, “jER1009” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent of about 3000, number average molecular weight of about 3750) was used. Table 5 shows the molar ratio of epoxy resin / 3-amino-1,2,4-triazole in the epoxy resin solution R8.

Using the various plated steel sheets shown in Table 9 as the processing original plate, the surface of the plated steel sheet is subjected to alkaline degreasing treatment, washed with water and dried, then treated (applied) with a treatment liquid for forming a lower layer film as necessary, and dried at various temperatures. I let you. Subsequently, the coating composition for organic membrane formation was apply | coated, and it was made to dry at various temperature, and obtained the surface treatment steel plate of the example of this invention and the comparative example. In addition, the film thickness of the lower layer film and the organic film was adjusted by the solid content (heating residue) of the film composition, the processing time, and the like.
The results of evaluating the quality performance (white rust resistance, white rust resistance after alkali degreasing, electrical conductivity, abrasion resistance) of the obtained surface-treated steel sheets are shown in Tables 10 to 15 together with the production conditions and the coating composition. In Examples of Tables 10 to 15, No. 1-No. 52 is a surface-treated steel sheet having no lower layer coating.
The measurement and evaluation methods for each quality performance are as follows.

(1) White rust resistance About each sample, the salt spray test (JIS-Z-2371) was given and it evaluated by the white rust area rate after 300 hours. The evaluation criteria are as follows.
◎: White rust occurrence area ratio less than 5% ○: White rust occurrence area ratio 5% or more and less than 10% ○-: White rust occurrence area ratio 10% or more and less than 25% △: White rust occurrence area ratio 25% or more Less than 50% x: White rust generation area ratio 50% or more

(2) White rust resistance after alkaline degreasing Each sample was subjected to alkaline degreasing with an alkali treatment liquid “CLN-364S” (60 ° C., spray 2 minutes) manufactured by Nihon Parker Rising Co., Ltd. A spray test was performed, and the white rust area ratio after 150 hours was evaluated. The evaluation criteria are as follows.
◎: White rust occurrence area ratio less than 5% ○: White rust occurrence area ratio 5% or more and less than 10% ○-: White rust occurrence area ratio 10% or more and less than 25% △: White rust occurrence area ratio 25% or more Less than 50% x: White rust generation area ratio 50% or more

(3) Conductivity The interlayer insulation resistance value was measured based on JIS-C-2550. The evaluation criteria are as follows.
○: 3Ω · cm less than ² / sheets △: 3~5Ω · cm ² / sheet ×: 5Ω · cm ² / sheet exceeded (4) with resistance to abrasion resistance rubbing tester (by Taihei Rika Kogyo Ltd. Co.), the After rubbing the sample with corrugated cardboard, the surface of the sample was visually observed and evaluated according to the following evaluation criteria. The test was performed at 400 g (surface pressure 9.8 kPa), sliding distance 60 mm, speed 120 mm / s, and number of rubbing times 1000 times.
◎: The number of wrinkles is 0 ○: The number of wrinkles is 1 to 2 Δ: The number of wrinkles is 3 to 10 ×: The number of wrinkles is 11 or more or discolored (number cannot be measured)

  According to Tables 10-15, the examples of the present invention are excellent in white rust resistance and white rust resistance (corrosion resistance) after alkali degreasing, conductivity, and abrasion resistance. On the other hand, in the comparative example, one or more of white rust resistance and white rust resistance (corrosion resistance) after alkali degreasing, conductivity and abrasion resistance are inferior to those of the present invention.

In addition, * 1 to * 13 described in Tables 10 to 15 indicate the following contents.
* 1 No. described in Table 9 (Plated steel plate)
* 2 No. described in Table 1. (silica)
* 3 No. described in Table 2 (Phosphoric acid / phosphoric acid compound)
* 4 No. in Table 3 (Metal compound)
* 5 No. described in Table 4. (Vanadium compounds)
* 6 IH: high frequency induction heating furnace AH: hot air furnace * 7 (Resin composition)
* 8 No. in Table 6 (Curing agent)
* 9 Mass ratio A: B of solid content of epoxy resin (A) and curing agent (B)
* 10 No. in Table 7 (Solid lubricant)
* 11 Mass ratio of the total content of epoxy resin (A) and curing agent (B) and solid lubricant (C) (A + B): C
* 12 No. in Table 8 (Anti-rust additive)
* 13 Mass ratio of total epoxy resin (A) and curing agent (B) to rust preventive additive (D) (A + B): D

Claims (7)

An epoxy resin (a1) and a cyclic ester compound (a2) represented by the following formula (2) are added to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet [number of moles of epoxy resin (a1)] / [cyclic ester compound]. The number of moles of (a2)] obtained by reacting under the condition of 0.05 to 0.5, an epoxy resin (A) having a primary hydroxyl group in the resin,

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by having an organic film having a film thickness of 0.1 to 5 μm formed by drying. On the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, there is a lower layer film that does not contain chromium, and the epoxy resin (a1) and the cyclic ester compound (a2) represented by the following formula (2) are Epoxy resin having a primary hydroxyl group in the resin (A) obtained by reacting under conditions of mol number of epoxy resin (a1) / [mol number of cyclic ester compound (a2)] = 0.05 to 0.5 (A )When,

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by having an organic film having a film thickness of 0.1 to 5 μm formed by drying. The lower layer film is made of (α) silica, (β) phosphoric acid and / or a phosphoric acid compound, and (γ) Mg, Mn, Al, or one or more kinds of metals (provided that the compound and / or the composite compound is used) And (σ) a tetravalent vanadium compound, and the adhesion amount of each of these components is
(Α) Silica: ₁ to 2000 mg / m ^{2 in} terms of SiO ²
(Β) Phosphoric acid and / or phosphoric acid compound: 1 to 1000 mg / m ^{2 in} total in terms of P
(Γ) One or more metals selected from Mg, Mn, and Al: 0.5 to 800 mg / m ^{2 in} total in terms of Mg, Mn, and Al
(Σ) Tetravalent vanadium compound: 0.1 to 50 mg / m ^{2 in} terms of V
The surface-treated steel sheet having excellent corrosion resistance, electrical conductivity, and abrasion resistance according to claim 2.   The epoxy resin (A) is an epoxy resin in which an epoxy group is modified with an active hydrogen-containing compound, and a part or all of the active hydrogen-containing compound is a hydrazine derivative having active hydrogen. A surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance according to any one of 1 to 3. The coating composition for forming an organic film further comprises one or more rust preventive additives (D) selected from the following (a) to (e): an epoxy resin (A) and a curing agent (B). The surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance according to any one of claims 1 to 4, comprising 1 to 100 parts by mass with respect to a total of 100 parts by mass of solids.
(A) Phosphate (b) Ca ion exchange silica (c) Molybdate (d) Silicon oxide (e) One or more selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams Organic compounds An epoxy resin (a1) and a cyclic ester compound (a2) represented by the following formula (2) are added to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet [number of moles of epoxy resin (a1)] / [cyclic ester compound]. The number of moles of (a2)] obtained by reacting under the condition of 0.05 to 0.5, an epoxy resin (A) having a primary hydroxyl group in the resin,

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by forming an organic film having a film thickness of 0.1 to 5 μm by heating and drying at an ultimate plate temperature of 50 to 350 ° C. Manufacturing method. A lower layer film not containing chromium is formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, and then the epoxy resin (a1) and the cyclic ester compound (a2) represented by the following formula (2) are formed on the surface of the lower layer film. ) Having a primary hydroxyl group in the resin obtained by the reaction of [number of moles of epoxy resin (a1)] / [number of moles of cyclic ester compound (a2)] = 0.05 to 0.5. Epoxy resin (A),

(In the formula, R = H or CH ₃ , n is 3 to 6)
It contains a curing agent (B) having a group that crosslinks with a hydroxyl group and a solid lubricant (C), and the mass ratio (A) / (B) of the epoxy resin (A) and the curing agent (B) is 95 / 5 to 55/45, a coating composition in which the blending amount of the solid lubricant (C) is 1 to 80 parts by mass with respect to a total of 100 parts by mass of the solids of the epoxy resin (A) and the curing agent (B) is applied. And a surface-treated steel sheet excellent in corrosion resistance, conductivity and abrasion resistance, characterized by forming an organic film having a film thickness of 0.1 to 5 μm by heating and drying at an ultimate plate temperature of 50 to 300 ° C. Manufacturing method.