JP3383596B2 - Organic coated steel sheet with excellent corrosion resistance - Google Patents

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 which is most suitable for automobiles, home appliances, building materials, etc. In order to adapt to environmental problems such as volatilization and elution of harmful substances from products, environmentally-friendly surface treatment that does not contain heavy metals such as chromium, lead, cadmium, and mercury that are harmful to the environment and human body during manufacturing and products. It relates to a steel plate.

[0002]

2. Description of the Related Art The purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet for steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles. Therefore, a steel sheet that has been subjected to a chromate treatment with a treatment liquid containing chromic acid, dichromic acid or a salt thereof as a main component is widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.

However, since the chromate treatment uses hexavalent chromium which is a pollution control substance, chromate has a bad influence on the human body in the treatment process, and it is difficult to dispose of the chromium sludge after the wastewater treatment. However, there are various problems such as the possibility that hexavalent chromium may be eluted from the product after chromate treatment. For this reason, as chromic acid usage control standards become stricter, management of chromate treatment plants, wastewater treatment, secondary contamination by chromate treatment products, etc. are becoming a problem, and in response to this, each plant has closed wastewater relations. , We are taking measures to prevent chromium ions from being discharged to the outside.
Also, in the process of degreasing the rust preventive oil and press oil adhered to the chromate-treated steel sheet by the user, when an alkaline degreasing liquid is used, the elution of chromium in the degreasing liquid is considerably large, so the degreasing liquid Dechrome treatment is required.

In view of the above, in order to prevent the occurrence of white rust on zinc-based plated steel sheets, many pollution-free treatment techniques have been proposed that do not rely on chromate treatment. Among them, some methods using organic compounds and organic resins have been proposed, and the following methods can be mentioned, for example.

(1) Method using tannic acid (for example,
(JP-A-51-71233) (2) A method using a thermosetting coating material in which an epoxy resin, an amino resin and tannic acid are mixed (for example, JP-A-63-9).
(0581) (3) A method using a mixed composition of an aqueous resin and a polyhydric phenolcarboxylic acid (for example, JP-A-8-325760).
How to utilize the chelating power of tannic acid such as

(4) A surface treatment method in which an aqueous solution of a hydrazine derivative is applied to the surface of a tin plate or a zinc iron plate (for example,
Japanese Patent Publication No. 53-27694, Japanese Patent Publication No. 56-10386
(5) A method of using a rust preventive agent containing an amine addition salt obtained by adding an amine to a mixture of acyl sarcosine and benzotriazole (for example, JP-A-58-130284).
(6) A method using a treating agent in which a heterocyclic compound such as a benzothiazole compound and tannic acid are mixed (for example, JP-A-57-198267).

[0007]

However, these conventional techniques have the following problems. First, all of the above methods (1) to (4) have problems in terms of corrosion resistance and the like. That is, the method (1) has insufficient corrosion resistance, and a uniform appearance after treatment cannot be obtained. In addition, the method of (2) above is a method of forming a thin film (0.1 to 5 μm) directly on a zinc-based or aluminum-based plating surface.
It is not intended to form the rust-preventive film of m), and therefore, even if it is applied in a thin film on the surface of zinc-based or aluminum-based plating, a sufficient anticorrosive effect cannot be obtained. Similarly, the method (3) also has insufficient corrosion resistance.

Furthermore, the above method (4) is not applied to a zinc-based or aluminum-based plated steel sheet, and even if it is applied to a zinc-based or aluminum-based plated steel sheet, the obtained film has a network structure. It does not have sufficient barrier properties, and therefore has insufficient corrosion resistance. In addition, Japanese Examined Japanese Patent Publication No. 53-23772
JP-B-56-10386, a water-soluble polymer compound (polyvinyl alcohol, maleic acid ester copolymer, acrylic acid ester copolymer, etc.) is mixed with an aqueous solution of a hydrazine derivative in order to improve the uniformity of the film. However, sufficient corrosion resistance cannot be obtained with a simple mixture of an aqueous solution of a hydrazine derivative and a water-soluble polymer compound.

Further, the above methods (5) and (6) are not aimed at forming a rust-preventive coating on the surface of a zinc-based or aluminum-based plated steel sheet in a short time.
Even if the treating agent is applied to the surface of the plated steel sheet, excellent corrosion resistance cannot be obtained because there is no barrier against corrosion factors such as oxygen and water. Regarding the method (6), mixing with a resin (epoxy resin, acrylic resin, urethane resin, nitrocellulose resin, vinyl chloride resin, etc.) as an additive is also described, but a complex such as a benzothiazole compound is mentioned. Sufficient corrosion resistance cannot be obtained with a simple mixture of a ring compound and a resin.

Further, in any of the above methods (1) to (6), in order to remove the oil applied to the surface by pressing or the like, alkaline degreasing of about pH 9 to 11 by spraying or the like is carried out under practical conditions. In the above, there is a problem that the film is peeled off or damaged by alkali degreasing, and the corrosion resistance cannot be maintained. Therefore, these methods are not suitable for practical use as a method for forming a rust preventive film. Therefore, an object of the present invention is to solve the problems of the prior art and to provide an organic coated steel sheet which can obtain excellent corrosion resistance without containing a heavy metal such as hexavalent chromium in the coating.

[0011]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to solve the above problems, a specific chelate-forming resin film is formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. As a result, it has been found that an organic coated steel sheet that is pollution-free and has excellent corrosion resistance can be obtained without performing a chromate treatment that may adversely affect the environment and the human body. The present invention has been made on the basis of such knowledge, and the characteristic configuration is as follows.

[1] An active hydrogen-containing compound (a) containing a film-forming organic resin (A) and a hydrazine derivative (C) in which some or all of the compounds have active hydrogen on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet ( An organic coated steel sheet having excellent corrosion resistance, which has an organic film having a film thickness of 0.1 to 5 μm containing a reaction product with B). [2] An organic coated steel sheet having excellent corrosion resistance, characterized in that, in the organic coated steel sheet of [1] above, the film-forming organic resin (A) is an epoxy group-containing resin (D). [3] In the organic-coated steel sheet according to [1] or [2], the hydrazine derivative (C) having active hydrogen is a pyrazole compound having active hydrogen and / or a triazole compound having active hydrogen. Organic coated steel sheet with excellent corrosion resistance.

[4] In the organic coated steel sheet according to any one of the above [1] to [3], a hydrazine derivative (C) having active hydrogen
Is contained in the active hydrogen-containing compound (B) in an amount of 10 to 100 mol%, which is an organic coated steel sheet having excellent corrosion resistance. [5] In the organic coated steel sheet according to any one of the above [2] to [4],
An organic coated steel sheet having excellent corrosion resistance, wherein the epoxy group-containing resin (D) is an epoxy resin represented by the following formula (1).

[Chemical 2]

The organic coated steel sheet of the present invention is characterized in that the film-forming organic resin (A) is reacted with the active hydrogen-containing compound (B) which is a hydrazine derivative (C) in which some or all of the compounds have active hydrogen. As a result, the hydrazine derivative (C) as a chelate-forming group is added to the film-forming resin (A).
Is added, and the chelate-forming resin that is the reaction product is formed as a rust-preventive film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet.

Although the anticorrosion mechanism of the organic film by such a specific reaction product is not always clear, by adding a hydrazine derivative to the film-forming organic resin instead of a low molecular weight chelating agent, (1) The organic polymer film has the effect of blocking corrosion factors such as oxygen and chlorine ions, and (2) the hydrazine derivative is adsorbed on the surface of the plating film or reacts with the plating film surface to stabilize the plating film surface. And (3) a hydrazine derivative that traps zinc ions eluted during film formation and is electrically neutral insoluble chelate compound layer (dense barrier of complex structure) Layer), the formation of the ion conductive layer at the interface between the plating film and the organic resin layer is suppressed, and the progress of corrosion is suppressed. 4) Furthermore, even in a corrosive environment, the free hydrazine derivative in the film traps zinc ions generated by corrosion, and the formation of a stable metal complex structure suppresses the progress of corrosion.
The progress of corrosion is effectively suppressed by the effects of
It is considered that excellent corrosion resistance can be obtained.

When an epoxy group-containing resin is used as the film-forming organic resin (A), a dense barrier film is formed by the reaction between the epoxy group-containing resin and the cross-linking agent, and this barrier film contains oxygen. Since it has an excellent ability to suppress the penetration of corrosion factors such as, and the hydroxyl group in the molecule provides an excellent binding force to the base material, particularly excellent corrosion resistance is obtained. Furthermore, a hydrazine derivative (C) having active hydrogen
In particular, by using a pyrazole compound having active hydrogen and / or a triazole compound having active hydrogen, more excellent corrosion resistance can be obtained.

Film-forming organic resin (A) as in the prior art
The effect of improving the corrosion inhibition is hardly recognized by simply mixing the hydrazine derivative (C) with the above. The reason is,
It is considered that the hydrazine derivative which is not incorporated in the molecule of the film-forming organic resin is adsorbed on the metal surface, but the adsorption product does not form a dense barrier layer due to its low molecular weight. On the other hand, by incorporating a hydrazine derivative into the molecule of the film-forming organic resin (A) as in the present invention, a markedly excellent corrosion inhibition effect can be obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention and the reasons for limitation thereof will be described below. Examples of the zinc-based plated steel sheet as the base of the organic coated steel sheet of the present invention include a galvanized steel sheet and Zn-Ni.
Alloy-plated steel sheet, Zn-Fe alloy-plated steel sheet (electroplated steel sheet and galvannealed steel sheet), Zn-Cr
Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-C
o 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 plated steel sheet (for example, Z
n-5% Al alloy plated steel plate, Zn-55% Al alloy plated steel plate), Zn-Mg alloy plated steel plate, Zn-Al-
It is possible to use Mg plated steel sheets, and further zinc-based composite plated steel sheets (for example, Zn—SiO ₂ dispersion plated steel sheets) in which metal oxides, polymers and the like are dispersed in the plating films of these plated steel sheets.

Further, it is also possible to use a multi-layer plated steel sheet obtained by plating two or more layers of the same kind or different kinds among the above-mentioned plating. Further, as the aluminum-based plated steel sheet which is the base of the organic coated steel sheet of the present invention, an aluminum-plated steel sheet, an Al-Si alloy-plated steel sheet, or the like can be used. Further, as the plated steel sheet, a steel sheet surface may be preliminarily plated with Ni or the like and then various kinds of plating as described above may be performed thereon. As the plating method, any of an electrolysis method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method and a vapor phase method can be adopted.

Next, a specific organic film formed on the surface of the zinc-plated steel sheet or the aluminum-plated steel sheet will be described. In the present invention, the organic coating formed on the surface of the zinc-plated steel sheet or the aluminum-plated steel sheet has an activity that comprises a film-forming organic resin (A) and a hydrazine derivative (C) in which some or all of the compounds have active hydrogen. An organic film having a film thickness of 0.1 to 5 μm containing a reaction product with the hydrogen-containing compound (B).

The type of film-forming organic resin (A) is as follows:
By reacting some or all of the compounds with the active hydrogen-containing compound (B) consisting of the hydrazine derivative (C) having active hydrogen, the active hydrogen-containing compound (B) is added or condensed to the film-forming organic resin. There is no particular limitation as long as it is a resin that can bond and form a film appropriately. Examples of the film-forming organic resin (A) include epoxy resin,
Examples include modified epoxy resins, polyurethane resins, polyester resins, alkyd resins, acrylic copolymer resins, polybutadiene resins, phenol resins, and adducts or condensates of these resins. They can be used alone or in combination of two or more.

As the film-forming organic resin (A),
A resin containing an epoxy group (epoxy group-containing resin) is particularly preferable from the viewpoints of reactivity, easiness of reaction, corrosion resistance and the like. As the epoxy group-containing resin (D),
By reacting some or all of the compounds with the active hydrogen-containing compound (B) consisting of the hydrazine derivative (C) having active hydrogen, the active hydrogen-containing compound (B) is added or condensed to the film-forming organic resin. There is no special restriction as long as it is a resin that can be bonded and can form a film appropriately.
Epoxy resins, modified epoxy resins, acrylic copolymer resins copolymerized with epoxy group-containing monomers, polybutadiene resins having epoxy groups, polyurethane resins having epoxy groups, and adducts or condensates of these resins. , One of these epoxy group-containing resins
The seeds may be used alone or in combination of two or more. Further, among these epoxy group-containing resins, thermosetting epoxy resins and modified epoxy resins having excellent barrier properties against corrosion factors such as oxygen are particularly suitable.

As the above-mentioned epoxy resin, polyphenols such as bisphenol A, bisphenol F and novolac type phenol are reacted with epihalohydrin such as epichlorohydrin to introduce a glycidyl group, or a reaction product of this glycidyl group is introduced. Further, there may be mentioned aromatic epoxy resins obtained by reacting polyphenols to increase the molecular weight, further aliphatic epoxy resins, alicyclic epoxy resins, etc. One of these may be used alone, or two or more of them may be mixed. Can be used.
It is preferable that these epoxy resins have a number average molecular weight of 1500 or more, particularly when film forming properties at low temperatures are required.

Examples of the above modified epoxy resin include resins obtained by reacting various modifying agents with the epoxy groups or hydroxyl groups in the above epoxy resin. For example, epoxy ester resin obtained by reacting a drying oil fatty acid, acrylic acid or Examples thereof include epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing methacrylic acid and the like, and urethane modified epoxy resin reacted with an isocyanate compound.

As the acrylic copolymer resin copolymerized with the above epoxy group-containing monomer, an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component containing an acrylate ester or a methacrylate ester as an essential component are dissolved in a solution. A resin synthesized by a polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like can be given.

As the above-mentioned polymerizable unsaturated monomer component,
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, propyl (meth) acrylate, n-,
C1-24 alkyl ester of acrylic acid or methacrylic acid such as iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate; Acrylic acid, methacrylic acid, styrene, vinyltoluene, acrylamide, acrylonitrile, N-methylol (meth) acrylamide, C1-4 alkyl ether compound of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate and the like. it can.

Further, as the unsaturated monomer having an epoxy group, glycidyl methacrylate, glycidyl acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate and the like are special as long as they have an epoxy group and a polymerizable unsaturated group. There are no restrictions. Further, the acrylic copolymer resin copolymerized with the epoxy group-containing monomer may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.

Particularly preferable as the epoxy resin is a resin having a chemical structure represented by the following formula (1), which is a reaction product of bisphenol A and epihalohydrin, and this epoxy resin is particularly excellent in corrosion resistance. preferable.

[Chemical 3] A method for producing such a bisphenol A type epoxy resin is widely known in the art. In the above chemical structural formula, q is 0 to 50, preferably 1 to 40, and particularly preferably 2 to 20. The film-forming organic resin (A) may be any of organic solvent-soluble type, organic solvent-dispersed type, water-soluble type, and water-dispersed type.

In the present invention, the purpose is to add a hydrazine derivative into the molecule of the film-forming organic resin (A), and therefore at least a part (preferably all) of the active hydrogen-containing compound (B) is active hydrogen. It is necessary that the hydrazine derivative (C) has

When the film-forming organic resin (A) is an epoxy group-containing resin, examples of the active hydrogen-containing compound (B) that reacts with the epoxy group include the compounds shown below. You can use more than one seed,
Also in this case, at least a part (preferably all) of the active hydrogen-containing compound (B) needs to be a hydrazine derivative having active hydrogen.・ Hydrazine derivatives having active hydrogen ・ Primary or secondary amine compounds having active hydrogen ・ Organic acids such as ammonia and carboxylic acid ・ Hydrogen halides such as hydrogen chloride ・ Alcohols, thiols ・ Active hydrogen Quaternary chlorinating agent which is a hydrazine derivative or a mixture of a tertiary amine and an acid

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

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-methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazind Triazole compounds such as lysine;

5-phenyl-1,2,3,4-tetrazole, 5-mercapto-1-phenyl-1,2,
Tetrazole compounds such as 3,4-tetrazole; 5-Amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole and other thiadiazole compounds; maleic hydrazide, 6- Pyridazine compounds such as methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone

Among these, a 5-membered ring or a 6-membered ring
Pyrazole compounds and triazole compounds having a membered ring cyclic structure and having a nitrogen atom in the cyclic structure are particularly preferable. These hydrazine derivatives can be used alone or in combination of two or more.

Typical examples of the above-mentioned amine compound having active hydrogen which can be used as a part of the active hydrogen-containing compound (B) include the following. A primary amino group of an amine compound containing one secondary amino group such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine and one or more primary amino groups is converted into a ketone, an aldehyde, or a carboxyl group. Acid and eg 1
A compound modified by heating to a temperature of about 00 to 230 ° C. to give an aldimine, ketimine, oxazoline or imidazoline;

Diethylamine, diethanolamine, di-n- or -iso-propanolamine, N
-Secondary monoamines such as methylethanolamine and N-ethylethanolamine; secondary amine-containing compounds 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 with ketimine;

The above-mentioned quaternary chlorinating agent which can be used as a part of the active hydrogen-containing compound (B) is used because the hydrazine derivative having no active hydrogen or the tertiary amine itself has no reactivity with the epoxy group. Is a mixture with an acid so that it can react with an epoxy group. The quaternary chlorinating agent reacts with the 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 is
Any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid may be used. Examples of the hydrazine derivative having no active hydrogen used to obtain the quaternary chlorinating agent include, for example, 3,
6-dichloropyridazine and the like, and examples of the tertiary amine include dimethylethanolamine, triethylamine, trimethylamine, triisopropylamine, methyldiethanolamine and the like.

The reaction product of the film-forming organic resin (A) and the active hydrogen-containing compound (B) consisting of a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is the film-forming organic resin (A). And the active hydrogen-containing compound (B) at 10 to 300 ° C., preferably 50 to 150 ° C. and about 1 to 8
It is obtained by reacting for about time.

This reaction may be carried out by adding an organic solvent, and the type of organic solvent 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. , Alcohols and ethers containing hydroxyl groups such as propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; esters such as ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate; toluene, xylene Such as aromatic hydrocarbons It can be used one or two or more thereof. Of these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with epoxy resin, film-forming property, and the like.

The compounding ratio of the film-forming organic resin (A) and the active hydrogen-containing compound (B), which is a hydrazine derivative (C) in which some or all of the compounds have active hydrogen, is a solid content. 0.5 to 20 parts by weight of the active hydrogen-containing compound (B) based on 100 parts by weight of the resin (A),
Particularly preferably, the amount is 1.0 to 10 parts by weight.

When the film-forming organic resin (A) is the epoxy group-containing resin (D), the mixing ratio of the epoxy group-containing resin (D) and the active hydrogen-containing compound (B) is The ratio [the number of active hydrogen groups / the number of epoxy groups] of the number of active hydrogen groups of the compound (B) and the number of epoxy groups of the epoxy group-containing resin (D) is 0.01 to 10, more preferably 0.1 to 8, It is more preferable to set it to 0.2 to 4 from the viewpoint of corrosion resistance and the like.

The ratio of the hydrazine derivative (C) having active hydrogen in the active hydrogen-containing compound (B) is 1
It is suitable to be 0 to 100 mol%, more preferably 30 to 100 mol%, and further preferably 40 to 100 mol%. If the proportion of the hydrazine derivative (C) having active hydrogen is less than 10 mol%, a sufficient rust preventive function cannot be imparted to the organic film, and the obtained rust preventive effect is obtained by simply mixing the film forming organic resin and the hydrazine derivative. It is almost the same as when it is used.

In the present invention, in order to form a dense barrier film, it is desirable to mix a curing agent in the resin composition and heat-cure the organic film. As the curing method for forming the resin composition film, (1) a curing method utilizing a urethanization reaction between an isocyanate and a hydroxyl group in the base resin, (2) a method selected from melamine, urea and benzoguanamine 1 to 5 carbon atoms in part or all of the methylol compound obtained by reacting formaldehyde with at least one species
The curing method utilizing the etherification reaction between the alkyl etherified amino resin obtained by reacting the monohydric alcohol with the hydroxyl group in the base resin is suitable. It is particularly preferable to use the urethanization reaction as the main reaction.

The polyisocyanate compound used in the curing method (1) above is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule, or an aromatic isocyanate compound thereof. It is a compound obtained by partially reacting a compound with a polyhydric alcohol. Examples of such polyisocyanate compounds include the following. m- or p-phenylene diisocyanate, 2,
4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate

The above compounds alone 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 and diether). Compounds in which at least two isocyanates remain in one molecule, which are reaction products with hexahydric alcohols such as pentaerythritol, etc. These polyisocyanate compounds may be used alone or in combination of two or more. Can be used.

Examples of the protective agent (blocking agent) for the polyisocyanate compound include aliphatic monoalcohols such as methanol, ethanol, propanol, butanol and octyl alcohol, and monoethers of ethylene glycol and / or diethylene glycol, for example, Methyl, ethyl, propyl (n-, iso), butyl (n-, iso, se)
c) etc. monoether phenol, aromatic alcohols such as cresol acetoxime, oximes such as methyl ethyl ketone oxime, etc. can be used, and at least at room temperature by reacting one or more of these with the polyisocyanate compound. It is possible to obtain a polyisocyanate compound stably protected with.

Such a polyisocyanate compound (E) as a curing agent is (A) / (E) = 95/5 to 55/45 (weight ratio of non-volatile content) to the film-forming organic resin (A), Preferably (A) / (E) = 90/10
It is suitable to mix in the ratio of 65/35. The polyisocyanate compound has water absorbability, which is (A) /
If it is blended in excess of (E) = 55/45, the adhesion of the organic film will be deteriorated. Furthermore, when topcoating is performed on the organic film, the unreacted polyisocyanate compound migrates into the coating film, causing inhibition of curing of the coating film and poor adhesion. From this point of view, it is preferable that the amount of the polyisocyanate compound (E) is (A) / (E) = 55/45 or less.

The film-forming organic resin (A) is sufficiently crosslinked by the addition of the above-mentioned crosslinking agent (curing agent).
Further, it is desirable to use a known curing accelerating catalyst in order to increase the low temperature crosslinkability. As the curing acceleration catalyst, for example, N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, bismuth nitrate or the like can be used. Further, for example, when an epoxy group-containing resin is used as the film-forming organic resin (A), in order to improve the physical properties such as adhesion, a known acrylic resin, alkyd,
A resin such as polyester may be mixed and used.

The organic coating film of the organic coated steel sheet of the present invention is usually an active hydrogen-containing compound (B) comprising a film-forming organic resin (A) and a hydrazine derivative (C) in which some or all of the compounds have active hydrogen. A reaction product (resin composition) as a main component, and if necessary, in addition to the above curing agent, as an additive, a lubricity-imparting agent (for example, polyethylene wax, a fluororesin compound), an anticorrosive additive (for example, , Silica), organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metallic dyes, etc.), inorganic pigments (for example, Titanium oxide), chelating agent (eg thiol etc.), conductive pigment (eg zinc,
It is possible to add metal powders of aluminum, nickel, etc., iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, silane coupling agents, titanium coupling agents, etc.), melamine / cyanuric acid adducts, etc. it can.

The coating composition for forming a film containing the above main component and additional components usually contains a solvent (organic solvent and / or water), and a neutralizing agent or the like is added if necessary. . The organic solvent is not particularly limited as long as it can dissolve or disperse the reaction product of the film-forming organic resin (A) and the active hydrogen-containing compound (B) and can be adjusted as a coating composition, and for example, Various organic solvents exemplified above can be used. The above-mentioned neutralizing agent is added as necessary in order to neutralize the film-forming organic resin (A) to make it aqueous, and when the film-forming organic resin (A) is a cationic resin. Acids such as acetic acid, lactic acid and formic acid can be used as neutralizing agents.

The organic film as described above is formed on the surface of a zinc-based plated steel plate or an aluminum-based plated steel plate without a chromate treatment film interposed. The dry film thickness of the organic film is 0.1 to 5 μm. If the thickness of the organic film is less than 0.1 μm, the corrosion resistance is insufficient. On the other hand, in general applications where weldability is required, if the thickness exceeds 5 μm, the weldability deteriorates. A more preferable film thickness is 0.5 to
It is 3 μm.

The organic coated steel sheet of the present invention is a reaction product of the above-mentioned film-forming organic resin (A) and an active hydrogen-containing compound (B) consisting of a hydrazine derivative (C) in which some or all of the compounds have active hydrogen. A coating composition containing a substance (preferably as a main component) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and dried. The surface of the plated steel sheet may be subjected to an alkaline degreasing treatment, if necessary, before the coating composition is applied, and further, a pretreatment such as a surface conditioning treatment may be performed in order to improve adhesion and corrosion resistance.

As a method of applying the coating composition onto the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, any method such as a coating method, a dipping method, and a spray method can be adopted. As a coating method, any method such as a roll coater (3 roll system, 2 roll system, etc.), a squeeze coater, a die coater or the like may be used. Further, it is possible to adjust the coating amount, make the appearance uniform, and make the film thickness uniform by an air knife method or a roll squeezing method after the coating treatment with a squeeze coater or the like, the dipping treatment or the spray treatment.

After the coating composition is applied, it is usually dried by heating without washing with water. However, since the organic film of the present invention is bonded to the surface of the plated steel sheet which is the base by chemical adsorption or reaction, a water washing step may be carried out after the coating composition is applied. A dryer, hot air oven, high-frequency induction heating oven, infrared oven, or the like can be used for the heating and drying treatment. It is desirable that the heat treatment is carried out at an ultimate plate temperature of 50 to 300 ° C, preferably 80 to 250 ° C. If the heating temperature is lower than 50 ° C, a large amount of water remains in the film, resulting in insufficient corrosion resistance. Further, if the heating temperature exceeds 300 ° C., not only is it uneconomical, but there is a risk that defects will occur in the coating and the corrosion resistance will decrease.

The present invention includes a steel sheet having the organic film as described above on both sides or one side. Therefore, examples of the form of the steel sheet of the present invention include the following. (1) One side: plating film-organic film, one side: plating film (2) One side: plating film-organic film, one side: known phosphate treatment film (3) Both sides: plating film-organic film

[0057]

EXAMPLES Examples of synthesizing a resin composition for forming a film are shown below. [Synthesis Example 1] 1870 parts of EP828 (produced by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 187) and bisphenol A91
2 parts, tetraethylammonium bromide 2 parts, and methyl isobutyl ketone 300 parts 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 1391 and a solid content of 90%. To this, ethylene glycol monobutyl ether 150
After adding 0 part, 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] 4000 parts of EP1007 (produced by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 2000) and 2239 parts of ethylene glycol monobutyl ether were placed in a four-necked flask, and the temperature was raised to 120 ° C. and completely completed in 1 hour. The epoxy resin was dissolved. This is 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 while cooling to obtain a triazole-modified epoxy resin having a solid content of 60%. This is designated as resin composition (2). This resin composition (2) contains 100 mol of a film-forming organic resin (A) and a hydrazine derivative (C) having active hydrogen.
% Active hydrogen-containing compound.

[Synthesis Example 3] 222 parts of isophorone diisocyanate (isocyanate equivalent 111) and 34 parts of methyl isobutyl ketone were charged in a four-necked flask, and 30 to 4 were charged.
Keep at 0 ° C methyl ethyl ketoxime (molecular weight 87) 8
After dropping 7 parts over 3 hours, the temperature 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%. Next, EP 828 (Okaka Shell Epoxy Co., Ltd., epoxy equivalent 187) 1496 parts, bisphenol A 684 parts, tetraethylammonium bromide 1 part, and methyl isobutyl ketone 241 parts were charged in a four-necked flask and heated to 140 ° C. for 4 hours. The reaction was performed to obtain an epoxy resin having an epoxy equivalent of 1090 and a solid content of 90%. To this, methyl isobutyl ketone 100
After adding 0 part, the mixture was cooled to 100 ° C., and 3-mercapto-
After adding 202 parts of 1,2,4-triazole (molecular weight 101) and reacting for 6 hours until the epoxy group disappears, 230 parts of the above partially blocked isocyanate having a solid content of 90% is added and reacted at 100 ° C. for 3 hours. It was confirmed that the isocyanate group disappeared. Furthermore, 461 parts of ethylene glycol monobutyl ether was added to give a solid content of 6
0% triazole modified epoxy resin was obtained. 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 in a four-necked flask and heated to 140 ° C. Raise the temperature and react for 4 hours,
An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this, 1500 parts of ethylene glycol monobutyl ether was added and then cooled to 100 ° C., 258 parts of dibutylamine (molecular weight 129) was added, and the reaction was allowed to proceed for 6 hours until the epoxy group disappeared, then methylisobutyl was added while cooling. Add 225 parts of ketone and solid content 60%
The epoxy amine adduct of was obtained. This is designated as resin composition (4). This resin composition (4) is a reaction product of a film-forming organic resin (A) and an active hydrogen-containing compound that does not contain a hydrazine derivative (C) having active hydrogen.

A curing agent was added to the resin compositions (1) to (4) synthesized as described above to prepare coating compositions shown in Table 1. In order to obtain an organic coated steel plate for home appliances, building materials, and automobile parts, the plate thickness is 0.8 mm and the surface roughness Ra is 1.
The coated steel sheet shown in Table 2 obtained by applying various zinc-based plating or aluminum-based plating to a 0 μm cold-rolled steel sheet was used as a treatment original plate, and after the surface of this plated steel sheet was subjected to alkaline degreasing treatment, washed with water and dried, the coating composition shown in Table 1 was obtained. The product was applied by a roll coater and heated and dried at various temperatures to produce an organic coated steel plate. The film thickness of the organic film was adjusted by the solid content (heating residue) of the coating composition or the coating conditions (roll rolling force, rotation speed, etc.).

The resulting organic coated steel sheet was evaluated for quality performance (film appearance, white rust resistance, paint adhesion).
The results are shown in Tables 3 to 5 together with the film constitution of the organic film. The quality performance of the organic coated steel sheet was evaluated as follows.

(1) Appearance of coating film Each sample was visually evaluated for uniformity of coating appearance (with or without unevenness). The evaluation criteria are as follows. ◯: Uniform appearance with no unevenness Δ: Appearance with some conspicuous unevenness ×: Appearance with conspicuous unevenness

(2) White rust resistance For each sample, salt spray test (JIS-Z-23
71) was carried out and the white rust generation area ratio after a predetermined time was evaluated. The evaluation criteria are as follows. ◎: White rust does not occur ○ +: White rust occurrence area ratio is less than 5% ○: White rust occurrence area ratio is 5% or more and less than 10% ○-: White rust occurrence area ratio is 10% or more and less than 25% △: White rust Occurrence area ratio 25% or more and less than 50% ×: White rust occurrence area ratio 50% or more

(3) Adhesion of paint For each sample, a melamine-based baking paint (film thickness 30
(μm), then soak it in boiling water for 2 hours, immediately cut a grid (10 × 10 grid at 1 mm intervals), apply and peel with an adhesive tape, and remove the coating film. The rate was evaluated. The evaluation criteria are as follows. ◎: No peeling ○: Peeling area ratio less than 5% △: Peeling area ratio 5% or more, less than 20% ×: Peeling area ratio 20% or more

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

As described above, the organic coated steel sheet of the present invention does not contain hexavalent chromium in the coating liquid of the treatment liquid or the product at the time of production, and is an organic coating for use in building materials, home appliances, automobiles, etc. It has a high degree of corrosion resistance as a steel plate, and also has a film appearance,
Excellent in paint adhesion.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Furuta 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Pipe Co., Ltd. (72) Inventor Masaru Sagiyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Pipe (72) Inventor Yasuhiko Haruta 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. (72) Inventor Hiroyasu Matsuki 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. ( 72) Inventor Kenichi Tomita 4-17-1, Higashi-Hachiman, Hiratsuka City, Kanagawa Kansai Paint Co., Ltd. (56) Reference JP-A-7-328536 (JP, A) JP-A-8-53632 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) C23F 11/00 C09D 163/02 C23F 11/14

Claims (5)

(57) [Claims] 1. An active hydrogen-containing compound (B) comprising a film-forming organic resin (A) and a hydrazine derivative (C) in which some or all of the compounds have active hydrogen on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. ), The organic coated steel sheet having excellent corrosion resistance, which has an organic film having a film thickness of 0.1 to 5 μm containing a reaction product with. 2. The organic coated steel sheet having excellent corrosion resistance according to claim 1, wherein the film-forming organic resin (A) is an epoxy group-containing resin (D). 3. A hydrazine derivative (C) having active hydrogen is a pyrazole compound having active hydrogen and / or
Alternatively, the organic coated steel sheet having excellent corrosion resistance according to claim 1 or 2, which is a triazole compound having active hydrogen. 4. The hydrazine derivative (C) having active hydrogen is contained in the active hydrogen-containing compound (B) in an amount of 10 to 100 mol%, which is excellent in corrosion resistance according to claim 1, 2 or 3. Organic coated steel sheet. 5. The organic coated steel sheet having excellent corrosion resistance according to claim 2, 3 or 4, wherein the epoxy group-containing resin (D) is an epoxy resin represented by the following formula (1). [Chemical 1]