JP2000290795A - Non-chromium type rust prevention treating method and rust prevention treated metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the adhesion property of a rust preventive film and to improve the corrosion resistance by executing an electrolytic treatment with a metallic material as a cathode with a specified current density to form a rust preventive film and coating the surface with a rust preventive coating agent having a specified compsn. SOLUTION: The electrolytic treatment is executed with a metallic material as a cathode with 0.1 to 50 A/dm2 current density in an aq. soln. contg. one or more kinds selected from among 0.2 to 100 g/l phosphoric ions, 0.2 to 100 g/l thiocarbonyl group-contg. compd., 0.2 to 100 g/l vanadic compd. and 0.2 to 100 g/l water-dispersible silica. In this way, on the surface of the metallic material, a 1st rust preventive film is formed to 1 to 1000 mg/m2 coating weight. Next, the surface of the film is coated with a rust preventive coating agent essentially consisting of a water base resin and water and contg. one or more kinds selected from among 0.2 to 50 g/l thicarbonyl group-contg. compd., 0.1 to 5 g/l phosphoric ions, 0.1 to 20 g/l vanadic compd. and 50 to 500 g/l water- dispersible silica to a thickness of 0.1 to 10 μm to form a 2nd rust preventive film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust-proofing method for a metal material, particularly for a galvanized steel sheet, and provides a rust-proofing method for imparting sufficient corrosion resistance to a metal material, and applying such a treatment. It is intended to provide a rust-proof metal material.

[0002]

2. Description of the Related Art Surface-treated steel sheets, such as galvanized steel sheets and zinc alloy-coated steel sheets, have a white rust on the surface in an atmosphere containing salt such as seawater or a high-temperature and high-humidity atmosphere, and significantly impair the appearance of the steel. Or the rust-preventive force on the surface is reduced

In order to prevent white rust, chromate-based rust preventive agents have been frequently used.
No. 370 describes a resin-based treating agent comprising a water-dispersible chromium compound and water-dispersible silica in an olefin-α, β-ethylenically unsaturated carboxylic acid copolymer resin dispersion.

[0004] Such a film made of a chromate-based treating agent is recognized as having the best corrosion resistance among known treating agents. However, its effect of preventing white rust is not always sufficient, and the plated steel sheet subjected to the chromate treatment also generates white rust when exposed to salt water or a high-temperature and high-humidity atmosphere for a long time. Further, a film formed by the chromate treatment contains hexavalent chromium, which is known to be a harmful element, and therefore, there is an increasing demand for a surface-treated steel sheet containing no hexavalent chromium.

[0005] Non-chromium rust preventive agents containing no harmful chromium are disclosed in JP-A-8-239776 and JP-A-8-6.
No. 7834, which uses sulfide and sulfur. However, not only sulfur but also some sulfides give off a peculiar odor, and handling of these treating agents was not always easy.

A rust preventive agent using a triazine thiol compound containing a sulfur atom but having no odor or toxicity has also been proposed. For example, JP-A-53-31737 discloses the addition of a dithiol-S-triazine derivative. The disclosed water-soluble anticorrosion paints are disclosed. However, this water-soluble anticorrosive paint is intended for anticorrosion of mild steel, copper, brass, etc.
In particular, when the substrate is made of copper or brass, it is prepared so as to be more easily adhered. Therefore, it is not sufficient as a rust inhibitor for metal surfaces such as zinc.

[0007] JP-A-61-223062 describes a reactive emulsion of a metal obtained by mixing a thiocarbonyl group-containing compound with an organic compound which is hardly soluble or insoluble in water. However, this emulsion also
It reacts with copper, nickel, tin, cobalt, aluminum and the like and their alloys, and is still insufficient as a rust inhibitor for metal surfaces such as zinc.

The applicants of the present application have disclosed in Japanese Patent Application No. 9-2557 a triazinethiol-containing rust-preventive coating agent which is also effective for rust-prevention of galvanized steel sheets. However, triazine thiol is an expensive compound, and thus a more inexpensive and effective rust preventive agent is required.

Chromium-free, triazine thiol
Not used, as a surface treatment method of zinc or zinc alloy,
JP-A-54-71734 and JP-A-3-2265.
No. 84 is disclosed. JP-A-54-
No. 71734 discloses a processing method described in Myo-Inositol.
From 2 to 6 linked phosphate esters or salts thereof.
5 to 100 g / l, titanium fluoride and zirconium fluoride
At least one of the compounds is 0.5 to 30 in metal conversion.
g / l and 1 to 50 g / l of thiourea or a derivative thereof.
Surface treatment of zinc or zinc alloy with an aqueous solution containing
It is. This method can be used as a protective layer on the zinc surface.
Titanium fluoride or zirconium to form oxide film
Requires fluoride. JP-A-3-226584
According to the report, Ni²⁺And Co²⁺0.02 g /
Compound having at least 1 and ammonia and a primary amine group
PH 5 to 10 containing at least one of
A surface treatment agent, which is an aqueous solution, is used. This process
Coating agents can be used to improve coating adhesion and corrosion resistance after coating.
Ni is applied by deposition of nickel.²⁺And Co ²⁺of
You need one or both. These metal ions
The treatment agent contained may increase the load during wastewater treatment, etc.
There was an inconvenience.

[0010]

As described above, conventional rust inhibitors containing no chromium are inferior to chromium-containing rust inhibitors in terms of corrosion resistance, and have other disadvantages as described above. Was. So, instead of chromium-containing rust inhibitor,
In addition, there has been a strong demand for the development of a new rust inhibitor that does not have the above-mentioned disadvantages.

[0011] As a new technique for satisfying such demands, the present applicant contains an organic resin and a thiocarbonyl group-containing compound or a vanadate compound which functions as an inhibitor, and contains a compound other than such an essential inhibitor component. Rust-preventive coating agent for plated steel sheet, which can contain phosphoric acid compound, thiocarbonyl group-containing compound or water-dispersible silica (Japanese Patent Application No. 10-362).
No. 64, Japanese Patent Application No. 10-36265, Japanese Patent Application No. 10-36
267). Since these new rust preventive coating agents do not contain chromium and have excellent corrosion resistance, they are expected to be used as rust preventive coating agents for galvanized or zinc alloy-plated steel sheets instead of conventional chromate-based treatment agents.

On the other hand, in order to sufficiently exhibit the performance of the rust-preventive coating agent, it may be desired to further improve the adhesion of the rust-preventive film formed thereby to the underlying metal material. As described above, thiocarbonyl group-containing compounds and the like are used as rust preventive agents. Even with a new rust preventive coating agent that does not contain chromium and has excellent corrosion resistance, the adhesion of the formed rust preventive film to the underlying metal material can be improved. Enhancing is very beneficial in further enhancing its practicality.

The present invention has been made in view of the above, and it is an object of the present invention to provide a rust preventive treatment method which is effective for improving the adhesion of a rust preventive film to a base metal material using the above-mentioned new rust preventive coating agent.

[0014]

The rust-preventive treatment method of the present invention comprises the steps of: providing 0.2 to 100 g of phosphate ions, 0.2 to 100 g of a thiocarbonyl group-containing compound in 1 liter of water,
0.2 to 100 g of the vanadate compound and 0.2 to 1
In an aqueous solution containing one or more kinds of water-dispersible silica of 00 g, a metal material was used as a cathode, and a current density of 0.1 to 5
The metal material is electrolytically treated at 0 A / dm ² to form a first rust-preventive film on the surface thereof, and then 1 liter of a composition mainly composed of an aqueous resin and water is formed on the first rust-preventive film. 0.2 in
５０50 g of thiocarbonyl group-containing compound, 0.1０．１5 g
Rust preventive coating by applying a rust preventive coating agent containing one or more of phosphate ions of 0.1 to 20 g of a vanadate compound and 50 to 500 g of water-dispersible silica Is formed.

Preferably, it is formed by the electrolytic treatment.
The amount of the first rust preventive coating is 1 mg / m ^Two~ 1000mg / m
^TwoIt is.

[0016] Preferably, the thickness of the second rust preventive film formed by the rust preventive coating agent is 0.1 to 10 µm.

Further, the rust-proofing metal material of the present invention is a metal material which has been treated by the above-described rust-proofing method.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Metals suitable for treatment with the method of the present invention are zinc coated steel, Al coated steel and uncoated steel. Specifically, the zinc-coated steel is a steel material that has been subjected to galvanization or an alloy plating of zinc and one or more of Fe, Ni, Co, Cr, Mg, Al, Si, Mn, and the like. Al-coated steel is, specifically, Al-plated or Al and Si, Mg, Fe, Mn, Co, Zn
Etc. refers to a steel material that has been subjected to alloy plating comprising one or two or more kinds. The plating method is not particularly limited, and may be any of an electroplating method, a hot-dip plating method, and a vacuum plating method. As the steel material, there is no particular limitation,
Various steel materials such as a cold-rolled steel plate, a hot-rolled steel plate, a thick plate, a steel bar, a wire rod, and a steel pipe may be used.

Generally, in order to perform rust prevention treatment on such a metal material with a rust prevention treatment coating agent, it is necessary to (1) prevent the penetration of a corrosive liquid, and (2) apply the rust prevention film to a metal substrate. (3) passivation of the metal surface by rust-preventive ions, etc .; and (4) the rust-preventive film must have water resistance, acid resistance, and alkali resistance. If any of these is insufficient, rust prevention cannot be exhibited. The chromium compound of the conventional rust inhibitor was mainly excellent in passivation. Here, passivation is
It refers to a state in which a metal or alloy retains inertness despite being an environment that can be chemically or electrochemically activated.

Since sulfides, like chromic acid, are easily adsorbed on the metal surface and have excellent oxidizing ability, they can passivate the metal surface. Therefore, the thiocarbonyl group-containing compound, which is one of the sulfides, has an effect of preventing white rust of zinc plating.

When a vanadium compound is added to such a rust-preventive coating agent containing a thiocarbonyl group-containing compound, the following rust-preventive action of vanadate ions is added to further promote the rust-preventive effect. In other words, the vanadate compound is ionized and dissolved in the rust preventive agent, and depending on the compound and the amount added, the dissolved amount as ions is saturated and dispersed as a solid in the rust preventive agent. It may be a pigment. In any case, the vanadate ions form a passive film on the zinc surface during application. This is the reason why the vanadate compound exhibits a rust preventive action. In addition, when water, which is a corrosion factor, penetrates into the rust-preventive film and a corrosion site is formed on the zinc surface, vanadate ions present in the film and vanadate ions eluted from the vanadate compound by the permeated water. Is thought to act on the corrosion site to suppress the corrosion reaction.

When the vanadate ion coexists with the thiocarbonyl group-containing compound or the phosphate ion, a synergistic action with them is developed. The reason for this synergism is not clear, but vanadate ions form a passive film at sites where phosphate or thiocarbonyl group-containing compounds cannot be adsorbed, or vice versa. It is considered that a phosphate ion or a thiocarbonyl group is adsorbed on a defective portion of the film to supplement the action of the vanadate ion, thereby obtaining a synergistic effect of the anticorrosion action.

Further, when phosphate ions are added, the rust-preventing effect of the thiocarbonyl group-containing compound is remarkably improved, and a rust-preventive coating agent superior to the conventional chromium-containing resin-based rust-preventive agent can be obtained. It is presumed that this is because the rust-preventing effect is exhibited by the synergistic action of the thiocarbonyl group-containing compound and the phosphate ion. That is, it is presumed that (1) the ion of the thiol group in the thiocarbonyl group-containing compound is adsorbed to the site on the zinc surface at the time of application of the rust preventive coating agent, and exhibits a rust preventive effect. Naturally, a sulfur atom easily forms a coordination bond with zinc, but a thiocarbonyl group (formula 1)

[0024]

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The compound having the formula (2)

[0026]

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As described above, those having both nitrogen atoms and oxygen atoms are more preferable. In these compounds, a nitrogen atom and an oxygen atom can also form a coordination bond with zinc. In particular, a thiocarbonyl compound having these atoms at the same time easily forms a chelate bond on the zinc surface and contains a thiocarbonyl group-containing compound. The compound can be strongly adsorbed on the zinc surface. A thiocarbonyl group-containing compound is not adsorbed to sites on the inactive zinc surface (eg, oxide surface), but phosphate ions act on such an inactive surface to form zinc phosphate. To form an active surface. Since the thiocarbonyl group-containing compound is adsorbed on the surface activated in this way, it is presumed that a rust-preventive effect is exerted on the entire zinc surface. Further, (2) both the thiocarbonyl group-containing compound and the phosphate ion act as a crosslinking accelerator of the resin film. It is presumed that the synergistic action of both can reduce the number of micropores in the resin film and efficiently block harmful ions such as water and chloride ions.

It should be noted that, in addition to the excellent rust-preventive action of the above-mentioned thiocarbonyl group-containing compound, phosphate ion and vanadate ion, the addition of water-dispersible silica to this further promotes the rust-preventive action. It was discovered. Water-dispersible silica adsorbs rust-preventive ions and molecules such as phosphate ions and thiocarbonyl group-containing compounds and vanadate ions onto the silica surface, and appropriately applies rust-preventive ions and the like to the galvanized surface where a corrosion reaction occurs. It is considered that the release of the molecules enhances the rust prevention effect.

As described above, the rust preventive used in the present invention is extremely effective in attaining passivation of the metal surface by rust preventive ions and the like, and usually forms an effective film as a rust preventive film. In order to do this, a resin as a film-forming component (in the case of the present invention, this resin is an organic resin derived from an aqueous resin due to the properties of the rust-preventive component of the present invention which is generally water-soluble)
Used as a mixture with However, in order to obtain sufficient performance as a rust-prevention treatment film, the rust-prevention film must have adhesiveness to the metal substrate, and if a film defect such as a scratch occurs in the rust-prevention film, It is important that the passivating ions are effectively supplied to the thiocarbonyl group-containing compound, the vanadate compound, and the phosphate ion, which are rust inhibitors in the present invention, are contained in the aqueous resin, and are applied to the metal substrate. -When dried, the concentration of the rust inhibitor on the surface of the substrate cannot be consciously increased, and in some cases, the effect of the rust inhibitor is limited in some cases. Therefore,
Prior to the application of a coating agent containing a resin, an electrolytic treatment is performed using a metal substrate as a cathode in an aqueous solution consisting of only a rust inhibitor, and the metal material surface is electrolytically reduced to expose the active surface, whereby the rust inhibitor is exposed. Fixed to the surface of the substrate in a sufficient amount,
It is possible to dramatically improve the adhesion between the subsequently applied aqueous resin layer and the base metal. Even when a film defect such as a flaw is introduced into the rust-preventive film, the rust-preventive agent adheres to the surface of the substrate, so that it is ionized by permeation of water and the like, and the surface surface is quickly passivated. And the corrosion resistance is further improved. This action guarantees more rust-preventive effect than can be obtained with a treatment layer coated with the rust-preventive agent-containing resin in one step.

Hereinafter, each component used in the present invention will be described in detail. In the present invention, the thiocarbonyl group-containing compound is a thiocarbonyl group represented by the following formula:

[0031]

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The compounds having the formula (I) may further include compounds capable of releasing a thiocarbonyl group-containing compound in an aqueous solution or under conditions in the presence of an acid or an alkali. Typically,

[0033]

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Thiourea and its derivatives, for example, methylthiourea, dimethylthiourea, ethylthiourea, diethylthiourea, diphenylthiourea, thiopental, thiocarbazide, thiocarbazones, thiocyanuric acids, thiohydantoin, 2-thiouramyl,
Such as thiourazole,

[0035]

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A thioamide compound represented by the formula:
Is, for example _{-H, -CH 3, -CH 2 CH} 3, -C 6 H
₅ etc.), for example, thioformamide, thioacetamide, thiopropionamide, thiobenzamide,
Thiocarbostyril, thiosaccharin, etc.

[0037]

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(Wherein R represents, for example, —H, —CH _3, etc.), for example, thioformaldehyde, thioacetaldehyde, etc.

[0039]

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Carbothioic acids represented by the formula (R in the formula:
For example -CH _3, represents a -C ₆ H _5, etc.), as an example, thioacetic acid, thiobenzoic acid, and the like dithio acetate, the formula

[0041]

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And thiocarbonates represented by the formula (1)
Compounds having the structure of, for example, thiocoumazone, thiocumothiazone, thionin blue J, thiopyrone, thiopyrine, thiobenzophenone and the like are exemplified. Among these compounds, those that do not directly dissolve in water are once dissolved in an alkaline solution and then incorporated into a rust preventive coating agent.

The vanadate compound may be a vanadate such as vanadate, ammonium vanadate, sodium vanadate, potassium vanadate, strontium vanadate, sodium hydrogen hydrogen vanadate, or a phosphovanadate such as phosphorus vanadate or ammonium phosphovanadate. It can be supplied in the form of salt or the like.

Phosphate ions form a phosphate layer on the metal substrate, passivate it, and significantly improve the adhesion between the resin layer and the substrate. Furthermore, when incorporated into a coating agent containing an aqueous resin, phosphate ions promote the crosslinking reaction of the resin film derived from the aqueous resin, and form a dense rust-preventive film. .

A phosphate ion source for supplying phosphate ions;
Orthophosphoric acid, condensed phosphorous, ortho metals
Phosphate or condensed phosphate, phosphorus pentoxide, phosphate ore
Product, commercially available composite phosphate pigment, or a mixture thereof
No. Some of the orthophosphates mentioned here are
Monohydrogen salt (HPO_Four ^2-Salt), dihydrogen salt (H_TwoPO_Four ^-
Salt). Water is also contained in the condensed phosphate.
It shall contain salt. In addition, metaphosphate
Acid salts, including ordinary polyphosphates and polymetaphosphates
Shall be included. Specific examples of these phosphorus compounds include
Phosphate minerals such as monetite, tolfillite,
Trock stone, xenotime, star collite, struv
Stone, orchidite, and commercially available complex phosphate pigments such as
Such as silica phosphate, complex phosphoric acid, for example, pyrophosphoric acid,
Metaphosphoric acid and complex phosphates such as metaphosphate, te
Trametaphosphate, hexametaphosphate, pyrophosphate
Salt, acid pyrophosphate, tripolyphosphate, or
These mixtures are mentioned. Metal forming phosphate
The species is not particularly limited, and alkali metals, alkaline earth gold
Genus, metal species of other typical elements and transition metals
It is. Examples of preferred metal species include magnesium and potassium.
Lucium, strontium, barium, titanium, zircon
, Manganese, iron, cobalt, nickel, zinc, aluminum
Luminium, lead, tin and the like can be mentioned. In addition to this
Oxo cations such as thiol, titanyl, zirconyl, etc.
You. Particularly preferred are calcium and magnesium.
You.

The water-dispersible silica used in the present invention is a silica having such a property that it has a fine particle size, so that when it is dispersed in water, it can maintain a stable state and no semi-permanent sedimentation is observed. It is a generic term. Such a water-dispersible silica is not particularly limited as long as it has a small amount of impurities such as sodium and is a weakly alkaline type. For example, "Snowtex N" (manufactured by Nissan Chemical Industries), "Adelite AT-20N" (manufactured by Asahi Denka Kogyo).
Commercially available silica gel, commercially available Aerosil powder silica particles, and the like can be used.

The aqueous resin used as the rust-preventive coating agent for forming the second rust-preventive film on the first rust-preventive film after the electrolytic treatment is not only water-soluble but also water-insoluble. However, the term also includes those in which an insoluble resin can be finely dispersed in water (a water-dispersible resin), such as an emulsion or a suspension. Such an aqueous resin is crosslinked or cured by heating and drying after applying a rust preventive coating agent to form an organic resin film containing a rust preventive component.

The resins that can be used as the aqueous resin include:
For example, polyolefin resin, acrylic olefin resin, polyurethane resin, acrylic resin, polycarbonate resin, epoxy resin, polyester resin, alkyd resin, phenol resin, and other heat-curable resins can be exemplified. It is more preferable that the resin is a crosslinkable resin. Particularly preferred resins are polyolefin-based resins, polyurethane-based resins, and mixed resins of both. The aqueous resin may be used as a mixture of two or more or copolymerization.

In the rust preventive treatment method of the present invention, the current density is 0.1 to 50 A /
By subjecting the metal material to electrolytic treatment with dm ² , the surface of the metal material is electrolytically reduced to expose the active surface, a rust inhibitor layer (first rust-preventive film) is formed on the surface of the underlying metal, and the metal surface is treated. In addition to passivation, the adhesion of the second rust preventive film containing a resin formed thereon is significantly improved.

In the electrolytic treatment, the metal material to be treated is immersed in an electrolytic solution containing one or more of a thiocarbonyl group-containing compound, a phosphate ion, a vanadate compound and water-dispersible silica, and this is treated with a cathode. By applying a voltage as described above, it can be easily performed in the production process of the metal material.
The applied voltage is adjusted so that the current density becomes 0.1 to 50 A / dm ² . The current density during the electrolytic treatment is 0.1 A /
In the case of less than dm ² , the electrolytic efficiency does not increase, so that a sufficient rust preventive film (first rust preventive film) cannot be formed, and 50 A /
dm ² more than the electrolytic plating layer would be excessively generated, there occurs unfavorable surface. More preferred current density is 0.5~20A / dm ^2. In addition, the electrolytic treatment itself of the metal material as used in the present invention is a well-known technique and does not need to be described in detail here.

The aqueous solution used for the electrolytic treatment may contain at least one of the above-described phosphate ions, thiocarbonyl group-containing compounds, vanadate compounds and water-dispersible silica. When the electrolytic treatment is performed in an aqueous solution composed of these components, hydrogen gas is generated on the cathode surface, and the surface is cleaned, and at the same time, the components in the aqueous solution are adsorbed, precipitated, and fixed. As a result, not only the adhesion of the resin film layer formed thereon is improved, but also when a defect causing corrosion (rust) of the metal material is introduced into the rust-preventive film, the base metal is not removed. The rust inhibitor adhered to the surface can be quickly eluted by permeation of water or the like, re-adsorbed to the metal surface, and passivated.

When the phosphate ion concentration is 0.2
If the amount is less than g / l, a sufficient rust preventive effect cannot be obtained.
If it exceeds 100 g / l, the rust-preventive action is saturated, which is uneconomical.

When the thiocarbonyl group-containing compound is added to the aqueous electrolytic solution, the amount is preferably 0.2 to 100 g per liter of the aqueous electrolytic solution. 0.2g / l
If the amount is less than the above, the effect of improving the corrosion resistance by the addition cannot be obtained so conspicuously. If the amount is more than 100 g / l, the corrosion resistance is saturated and uneconomical.

When a vanadate compound is added to the aqueous electrolytic treatment solution, the amount is preferably 0.2 to 100 g per liter of the aqueous electrolytic treatment solution. 0.2g /
When the amount is less than 1, the effect of improving the corrosion resistance by the addition is not conspicuously obtained, and when it exceeds 100 g / l, the corrosion resistance is saturated and uneconomical.

When water-dispersible silica is used, the amount added is 0.2% as solid content in 1 liter of the electrolytically treated aqueous solution.
It is preferred to have an amount of １００100 g. If it is less than 0.2 g / l, the effect of improving corrosion resistance cannot be expected so much.
If it exceeds 00 g / l, the corrosion resistance is saturated and uneconomical.

[0056] adhesion amount of the first rust preventing film formed by electrolytic ^{treatment, 1mg / m 2 ~1000mg / m} 2 is preferred.
If it is less than 1 mg / m ² , sufficient adhesion cannot be obtained,
If it exceeds mg / m ² , the film becomes brittle and sufficient adhesion cannot be obtained.

In the present invention, a second rust preventive film is formed by applying a rust preventive coating agent comprising an aqueous solution containing an aqueous resin on the first rust preventive film formed by the electrolytic treatment. Preferably, the rust-preventive coating agent for forming the second rust-preventive film is 1 liter of a composition containing 1 to 80 parts by weight of the above-described aqueous resin in solid content and 99 to 20 parts by weight of water. In addition, 0.2 to 50 g of a thiocarbonyl group-containing compound, 0.1 to 5 g of a phosphate ion, 0.1 to 2 g
0 g of the vanadate compound and 50 to 50 as solids
It contains one or more of 0 g of water-dispersible silica.

When the content of the thiocarbonyl group-containing compound in the rust preventive coating agent is less than 0.2 g / l, the corrosion resistance of the second rust preventive film becomes insufficient.
Depending on the aqueous resin used, the resin gels and cannot be applied.

When phosphate ions are used in the rust-preventive coating agent, if the amount is less than 0.1 g / l, a sufficient rust-preventing effect is not exhibited, while if it exceeds 5 g / l, the resin used In some cases, the resin gels and cannot be applied.

In the case where a vanadate compound is added to the rust preventive coating agent, if the amount is less than 0.2 g / l, the effect of improving the corrosion resistance will not be sufficiently exhibited, and
If it exceeds / 1, depending on the resin used, the resin gels and cannot be applied.

When water-dispersible silica is added to the rust preventive coating agent, the corrosion resistance of the formed second rust preventive film is further improved, and the drying property, scratch resistance and adhesion of the film are also improved. be able to. The amount of silica less than 50 g / l is insufficient to obtain the effect of the addition, whereas the amount of more than 500 g / l only saturates the effect and is uneconomical.

Further, the rust preventive coating agent of the present invention may further contain other components. For example, pigments, surfactants and the like can be mentioned. Further, a silane coupling agent or a hydrolyzed condensate thereof to improve the affinity between the aqueous resin and the silica particles and the pigment, and to further improve the adhesion between the aqueous resin and the zinc or iron phosphate layer, or Both of them may be blended. Here, the “hydrolysis condensate of a silane coupling agent” refers to an oligomer of a silane coupling agent obtained by subjecting a silane coupling agent to a raw material and hydrolyzing and polymerizing the same.

As the pigment, for example, titanium oxide (TiO 2)
₂ ), zinc oxide (ZnO), zirconium oxide (Zr
O), calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ), alumina (Al ₂ O ₃ ), kaolin clay, carbon black, iron oxide (Fe ₂ O ₃ , Fe ₃
Inorganic pigments such as O ₄ ) and organic pigments can be used.

The silane coupling agent which can be used in the present invention is not particularly limited, but preferred examples include the following: vinylmethoxysilane, vinyltrimethoxysilane, vinylethoxysilane, Vinyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N- (1,3-dimethylbutylidene) ) -3-
(Triethoxysilyl) -1-propanamine, N,
N′-bis [3- (trimethoxysilyl) propyl] ethylenediamine, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ
-Aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane,
N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane.

Particularly preferred silane coupling agents are vinyltrimethoxysilane, vinylethoxysilane, 3-
Aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N- (1,3-dimethylbutylidene)
-3- (triethoxysilyl) -1-propanamine,
N, N'-bis [3- (trimethoxysilyl) propyl] ethylenediamine. One of these silane coupling agents may be used alone, or two or more thereof may be used in combination.

In the present invention, the silane compound is added in an amount of 0.1 to 1 liter of a composition containing an aqueous resin and water as main components.
02 to 20 g (silica solid content ratio: about 0.04 to 40
%), Preferably 0.1 to 2.5 g (silica solid content ratio:
(About 0.2-5%). When the addition amount of the silane compound is less than 0.02 g, the effect of the addition is reduced, and the effect of improving the corrosion resistance and the adhesion of the top coat is insufficient.
If it exceeds g, the storage stability decreases, which is not preferable.

In the rust preventive coating agent used in the present invention, a solvent may be used in order to improve the film forming property of the aqueous resin and form a more uniform and smooth coating film. The solvent is not particularly limited as long as it is generally used in paints, and includes, for example, alcohols, ketones, esters,
Ether type compounds and the like can be mentioned.

In order to form a coating film on the first rust-preventive film formed by the electrolytic treatment using the above-mentioned rust-preventive coating agent, the rust-preventive coating agent is applied to a substrate provided with the first rust-preventive film. Then, it may be heated and dried. The coating method is not particularly limited, and the coating can be performed by generally used roll coating, air spray, airless spray, dipping, or the like. Heating and drying after coating are not particularly limited, and can be performed in a hot-blast furnace, a direct-fired furnace, an IH furnace, or the like. An appropriate heating temperature is 50 to 250 ° C. If the temperature is lower than 50 ° C., the evaporation rate of water is too slow to obtain a sufficient film-forming property, so that the rust-preventing ability is insufficient. On the other hand, when the temperature exceeds 250 ° C., thermal decomposition of the aqueous resin occurs, so that the salt spray resistance and the water resistance are reduced, and the appearance is yellowed. The drying time when the object to be coated is heated with hot air after application and dried is 1 second to 5 seconds.
Minutes are preferred. Further, the thickness of the second rust preventive film is desirably a dry film thickness of 0.1 μm or more. 0.1 μm
If it is less than the above, the rust-preventing ability is insufficient. On the other hand, if the dry film thickness is too large, problems such as cracks during processing occur, which is uneconomical, so that the thickness is preferably 20 μm or less, more preferably 0.1 to 0.1 μm.
10 μm.

[0069]

Next, the present invention will be further described with reference to examples.
In the following Examples and Comparative Examples, the concentration expressed in g / l means the content (g) of each component contained in 1 liter of the rust preventive coating composition. Further, in each of the following examples, 1 was measured by a salt spray test described below.
The secondary rust prevention (SST resistance) was evaluated.

According to a test method based on JIS Z2371, a 5% saline solution was sprayed on the surface of the substrate at 35 ° C.
The degree of white rust after time was evaluated on a scale of 1 to 10. The evaluation was performed for both the flat portion and the Ericksen 7 mm extruded portion. The evaluation criteria were as follows. 10 points: No abnormality 9 points: Between 10 and 8 points 8 points: Slightly white rust generated 7 points to 6 points: Between 8 and 5 points 5 points: White rust generated in half the area 4 to 2 points : Between 5 points and 1 point 1 point: White rust occurred on the entire surface

Example 1 50 g / l of ammonium vanadate, 50 g / l of thiourea, and 50 g / l of ammonium phosphate were dissolved in pure water, and finally water-dispersible silica "Snow" was dissolved. After adding 200 g / l of "Tex-N" (trade name, manufactured by Nissan Chemical Industries, Ltd.), the mixture was stirred and dispersed with a disper for 30 minutes, adjusted to pH 8.0, and the first layer (lower layer) of the rust preventive coating agent was added. Obtained. On the other hand, polyolefin resin "HITEC S-70" is added to pure water.
24 (trade name; manufactured by Toho Chemical Co., Ltd.) and polyurethane resin "Pontita HUX-320" (trade name; manufactured by Asahi Denka Co., Ltd.) so that the total concentration of resin solids is 20% by weight. The mixture was added at a ratio of 1: 1 (weight ratio) per minute, and ammonium vanadate 5 g / l, thiourea 5 g / l, and ammonium phosphate 5% / l were added.
g / l, and finally 100 g of water-dispersible silica "Snowtex-N" (trade name; manufactured by Nissan Chemical Industries, Ltd.).
/ L, and then dispersed by stirring with a disper for 30 minutes.
The pH was adjusted to 8.0 to obtain a second layer (upper layer) rust preventive coating agent.

Commercially available galvanized steel sheet "EP-MO"
(Nippon Text Panel, 70 × 150 × 0.8mm)
Was degreased with an alkaline degreaser (“Surf Cleaner 53”, manufactured by Nippon Paint Co., Ltd.), washed with water and dried. The plated steel sheet is immersed in the first layer of the rust-preventive coating agent containing no resin, the steel sheet is used as the cathode, the Pt-plated Ti plate is used as the anode, the current density is 10 A / dm ² , and the energizing time is 5
Treated as seconds. After energization, it was washed with water and dried. Further, a second layer of a rust-preventive coating agent containing a resin was further applied by bar coating # 3 so as to have a dry film thickness of 1 μm, and then dried so as to have a PMT (attained plate temperature) of 150 ° C. . The obtained sample was subjected to the above salt spray test for the evaluation of the primary rust prevention. The compositions and amounts of the first layer and the second rust preventive coating agent are shown in Tables 1 and 2, and the evaluation results are shown in Table 2.

[Examples 2 to 24] In Example 1, the addition amount of the thiocarbonyl group-containing compound, the addition amount of phosphate ion, the addition amount of Snowtex-N, and the addition amount of the vanadate compound in the first layer were changed. Kinds, further addition amount of thiocarbonyl group-containing compound of the second layer, addition amount of phosphate ion, addition amount of Snowtex-N, addition amount and type of vanadate compound, silane compound are described in Tables 1-4. A galvanized steel sheet which had been subjected to a rust-preventive treatment in the same manner as in Example 1 was obtained, except that the rust-preventive properties were evaluated. The evaluation results are shown in Tables 2 and 4. In Examples 17 to 24, the following silane compounds (silane coupling agents) were used. A: vinyltrimethoxysilane B: vinylethoxysilane C: 3-aminopropyltriethoxysilane D: 3-glycidoxypropyltrimethoxysilane E: 3-methacryloxypropyltrimethoxysilane F: 3-mercaptopropyltrimethoxysilane G: N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine H: N, N'-bis [3- (trimethoxysilyl) propyl] ethylenediamine

[Comparative Examples 1 to 4] The same treatment as in Example 1 was carried out except that the compositions and amounts of the rust preventive coating agents of the first and second layers were as shown in Tables 3 and 4, and the performance was as follows. An evaluation was performed. Table 4 shows the evaluation results.

[0075]

[Table 1]

[0076]

[Table 2]

[0077]

[Table 3]

[0078]

[Table 4]

[0079]

As described above, according to the present invention, a rust-inhibiting effect which is superior to that of a conventional chromate-containing aqueous resin-based rust-inhibiting agent is exerted, and further, the base metal material of the rust-inhibiting film is provided. It is possible to provide a surface-treated metal material excellent in non-adhesion to the surface.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yujiro Miyauchi 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside Nippon Steel Corporation (72) Inventor Atsushi Morishita 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation (72) Inventor Toshiaki Shimakura 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. (72) Katsuyoshi Yamazoe 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Inside the corporation

Claims (4)

[Claims] 1. One liter of water contains 0.2 to 100 g of phosphate ions, 0.2 to 100 g of a thiocarbonyl group-containing compound, 0.2 to 100 g of a vanadate compound, and 0.2 to 100 g of an aqueous dispersion. In an aqueous solution containing one or more kinds of conductive silica, a metal material is used as a cathode and the metal material is subjected to electrolytic treatment at a current density of 0.1 to 50 A / dm ² to form a first rust preventive film on its surface. Then, on the first rust preventive film, 0.2 to 50 g of a thiocarbonyl group-containing compound per liter of a composition containing an aqueous resin and water as main components,
By applying a rust preventive coating agent containing one or more of 0.1 to 5 g of phosphate ions, 0.1 to 20 g of a vanadate compound and 50 to 500 g of water-dispersible silica, A rust prevention treatment method characterized by forming a second rust prevention film. Wherein the adhesion amount of the first rust preventing film formed by the electrolytic treatment is ^{1mg / m 2 ~1000mg / m 2} ,
The method of claim 1. 3. The thickness of a second rust preventive film formed of the rust preventive coating agent is 0.1 to 10 μm.
Or the method of 2. 4. A rustproof metal material which has been treated by the method according to claim 1.