JP2000319787A - Chromium-free rust preventive coating steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce inexpensive non-chromium rust preventive coating steel having corrosion resistance equal to or above that of rust preventive treated steel using chromium. SOLUTION: The surface layer of zinc series metallic coating steel, aluminum- coated steel or noncoated steel is provided with a rust preventive coating layer composed of an organic resin of 100 pts.wt. a thiocarbonyl group-contg. compd. of 0.4 to 50 pts.wt. and a silane coupling compd. of 0.01 to 20 pts.wt. as solid contents. The rust preventive coating layer may contain a phosphoric acid compd. of 0.01 to 20 pts.wt., or may contain particulate silica of 1 to 500 pts.wt. as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion coated steel material containing no chromium.

[0002]

2. Description of the Related Art Galvanized steel sheets and alloyed galvanized steel sheets generate 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.
The rust-preventive force on the base iron surface is reduced.

In order to prevent the occurrence of white rust, chromate-based rust preventive agents have been frequently used.
No. 1370 discloses a resin-based treating agent containing a water-dispersible chromium compound and water-dispersible silica in an olefin-α, β-ethylenically unsaturated carboxylic acid copolymer resin dispersion.

However, even the above-mentioned chromium-containing resin-based treating agents do not always have sufficient corrosion resistance, and white rust is generated when exposed to salt water or a high-temperature and high-humidity atmosphere for a long time. In recent years, there has been an increasing demand for non-chromium rust preventive agents.

The inventors have found that sulfide ions react with zinc to form a stable ZnS film, and have already disclosed sulfide and sulfur in JP-A-8-239776 and JP-A-8-67834. It discloses a non-chromium rust preventive agent used.

[0006] However, some of the sulfides emit a peculiar odor, and the handling is not always easy.

Further, a rust preventive agent using a triazinethiol compound containing a sulfur atom and having no odor or toxicity has been proposed. For example, JP-A-53-31737 discloses a water-soluble anticorrosion paint to which a dithiol-S-triazine derivative is added.

[0008] Japanese Unexamined Patent Publication (Kokai) No. 61-222302 discloses a "reactive emulsion with a metal" which comprises a reaction between a compound containing a thiocarbonyl group and a metal obtained by mixing a hardly soluble or insoluble organic compound in water. Sex emulsions are disclosed.

[0009] However, Japanese Patent Application Laid-Open No. Sho 53-3173 discloses the above.
The water-soluble anticorrosion paint disclosed in Japanese Patent Publication No. 7 is intended for anticorrosion of mild steel, copper, brass, copper wire and the like, and is prepared so as to be more easily adhered particularly when the base material is copper or brass. I have. Therefore, it was insufficient as a rust inhibitor for metal surfaces such as zinc.

[0010] The reactive emulsion disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-222302 also includes copper, nickel,
Since it is an emulsion that reacts with tin, cobalt, aluminum and the like and alloys thereof, it was not sufficient as a rust preventive for metal surfaces such as zinc.

The present inventors have studied triazinethiol-containing rust-preventive coating agents which are also effective in preventing rust on galvanized steel sheets, and disclosed the triazinethiol-containing rust-preventive coating agents described in Japanese Patent Application No. 9-2557. . However, triazine thiol is an expensive compound, and a less expensive rust inhibitor has been desired.

As a surface treatment method for zinc or zinc alloy which does not contain chromium and does not use triazine thiol,
JP-A-54-71734 and JP-A-3-22658
No. 4 gazette. Japanese Patent Application Laid-Open No. 54-71734 discloses that 0.5 to 100 g / l of 2 to 6 bonded phosphate esters of myo-inositol or a salt thereof is selected from the group consisting of titanium fluoride and zirconium fluoride. A zinc or zinc alloy characterized in that zinc or a zinc alloy is surface-treated with an aqueous solution containing 0.5 to 30 g / l in terms of metal, and 1 to 50 g / l of thiourea or a derivative thereof in terms of metal. This is a surface treatment method. This technique requires titanium fluoride or zirconium fluoride to form a passivation film as a protective layer on the zinc surface. Japanese Unexamined Patent Publication No. Hei 3-226584 discloses a pH 5 having at least 0.02 g / l of one or two of Ni ²⁺ and Co ²⁺ and one or two of compounds having ammonia and a primary amine group. -10
Discloses a surface treatment agent which is an aqueous solution. This requires Ni ²⁺ and / or Co ²⁺ to impart paint adhesion and post-paint corrosion resistance by depositing cobalt or nickel. As described above, the treatment agent containing a metal ion has disadvantages such as an increase in load at the time of wastewater treatment.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an inexpensive, non-chromium rust-proof coated steel material having corrosion resistance higher than that of rust-prevention treated steel material using chromium. It is to be.

[0014]

The rust-preventive coated steel material according to the present invention, which achieves the above-mentioned object, comprises a zinc-based metal-coated steel, an aluminum-coated steel, or an uncoated steel having a solid content of 100 wt. And a rust-proof coating layer consisting of 0.4 to 50 parts by weight of a thiocarbonyl group-containing compound and 0.01 to 20 parts by weight of a silane coupling compound. In another embodiment of the rust-proof coated steel material of the present invention, the rust-proof coating layer may further contain 0.01 to 20 parts by weight of a phosphate compound.
In still another embodiment of the rust-proof coated steel material of the present invention, the rust-proof coating layer may further include 1 to 500 parts by weight of fine silica.

In general, in order to be effective as a rust-preventive coating layer, (1) to prevent penetration of a corrosive solution;
(2) The rust prevention film has adhesion to the metal substrate,
It is necessary to satisfy (3) passivation of the metal surface by rust preventive ions and the like, and (4) water resistance, acid resistance and alkali resistance of the rust preventive film. If any of these is insufficient, rust prevention cannot be exhibited. The chromium compound of the conventional rust preventive layer was mainly excellent in the passivation of (3). Here, the passivation means that a metal or an alloy is in a state of maintaining inertness despite being in a chemically or electrochemically active environment.

Since sulfides, like chromic acid, are easily adsorbed on metal surfaces and have excellent oxidizing ability, they can passivate metal surfaces. Therefore, one of the sulfides
The thiocarbonyl group-containing compound has an effect of preventing galvanization from white rust.

Further, when the thiocarbonyl group-containing compound is added together with phosphate ions to a rust-preventive coating agent containing an aqueous resin, the rust-preventing effect is remarkably improved, and is superior to conventional chromium-containing resin-based rust-preventing agents. A rustproof coating agent is 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) ions of the thiol group in the thiocarbonyl group-containing compound are adsorbed to sites on the active zinc surface during the application of the rust-preventive coating, thereby exhibiting a rust-preventive effect. Naturally, a sulfur atom easily forms a coordinate bond with zinc, but a thiocarbonyl group (formula I)

[0019]

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The compound having the formula (II)

[0021]

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As described above, those having both a nitrogen atom and an oxygen atom are preferable. In these compounds, a nitrogen atom or an oxygen atom can also form a coordination bond with zinc, so that a thiocarbonyl compound having these atoms at the same time easily forms a chelate bond on the zinc surface, and the thiocarbonyl compound is It can be considered that it can be firmly adsorbed on the surface, thereby obtaining a rust prevention effect.
The thiocarbonyl group-containing compound is not adsorbed to sites on the inactive zinc surface (for example, the surface of the oxide), but phosphate ions act on such inactive surfaces to cause zinc phosphate To form an active surface, and the thiocarbonyl group-containing compound is adsorbed on the surface thus activated. Therefore, when there is an inert zinc surface, it is presumed that by using phosphate ions in addition to the thiocarbonyl group-containing compound, a rust-preventing effect is exerted on the entire zinc surface. Further, (2) the thiocarbonyl group-containing compound is
It is thought to act as a crosslinking accelerator for the resin film, thereby reducing micropores in the resin film and blocking harmful ions such as water and chloride ions. Phosphate ions also act as a crosslinking accelerator for the resin film, so when the thiocarbonyl group-containing compound and phosphate ions coexist, the synergistic action of the two reduces the micropores in the resin film and reduces water and chlorine ions. It is estimated that harmful ions can be efficiently blocked.

It should be noted that, in addition to the excellent rust-preventing action of the above-mentioned thiocarbonyl group-containing compound or the coexistence of the thiocarbonyl group-containing compound and phosphate ion, the addition of water-dispersible silica to this compound further It has been discovered that the rust-preventing action is promoted. Furthermore, the adhesion between the aqueous resin and the zinc, Al or iron phosphate compound layer is dramatically improved by the addition of the silane coupling compound. Examples of the silane coupling compound include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-
(2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, Vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-
Mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane and the like can be mentioned.

The rust-preventive coating layer of the present invention contains a silane coupling compound in addition to the thiocarbonyl group-containing compound, thereby ensuring improved coating film adhesion.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the thiocarbonyl group-containing compound used in the rust-proof coating layer of the rust-proof coated steel material of the present invention will be described in detail. In the present invention, the thiocarbonyl group-containing compound refers to a thiocarbonyl group (I)

[0026]

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

Representative examples of the thiocarbonyl group-containing compound include compounds of the formula (III)

[0029]

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Thiourea and its derivatives represented by
For example, methylthiourea, dimethylthiourea, ethylthiourea, diethylthiourea, diphenylthiourea, thiopental, thiocarbazide, thiocarbazones, thiocyanuric acids, thiohydantoin, 2-thiouramil, 3
-Thiourazole and the like; Formula (IV)

[0031]

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A thioamide compound represented by the formula (V), such as thioformamide, thioacetamide, thiopropionamide, thiobenzamide, thiocarbostyril, thiosaccharin;

[0033]

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A thioaldehyde compound represented by the following formula: thioformaldehyde, thioacetaldehyde, etc .;

[0035]

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Carbothioic acids such as thioacetic acid, thiobenzoic acid and dithioacetic acid;

[0037]

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Thiocarbonates represented by the following formulas; other compounds having the structure of the formula (I), for example, thiocouzone, thiocumothiazone, thionin blue J, thiopyrone, thiopyrine,
Thiobenzophenone and the like can be exemplified. Among the above, those which do not directly dissolve in water are once dissolved in an alkaline solution and then blended in a rust preventive coating agent.

The silane coupling compound, which is another useful component in the coating layer composition of the present invention, comprises:
A substance generally known as a silane coupling agent, which forms a strong bond with the surface of a metal material and a phosphoric acid compound, and also bonds with a resin, thereby improving the adhesion of the film and improving the corrosion resistance. . If the content of the silane coupling compound is less than 0.01 part by weight, a sufficient effect of improving the adhesion of the coating film cannot be obtained. Adhesion decreases.

In the present invention, as the silane coupling compound, not only the silane coupling compound (silane coupling agent) itself, but also its hydrolytic condensate,
Alternatively, a mixture of a silane coupling compound and a hydrolyzed condensate can also be used. The hydrolyzed condensate of the silane coupling compound refers to an oligomer of the silane coupling compound obtained by hydrolyzing and polymerizing the silane coupling compound as a raw material.

The silane coupling compound which can be used in the present invention is not particularly limited, but preferred examples thereof 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 compounds are vinyltrimethoxysilane, vinylethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercapto Propyltrimethoxysilane, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N, N'-bis [3- (trimethoxysilyl)
Propyl] ethylenediamine. One of these silane coupling compounds may be used alone, or two or more thereof may be used in combination.

The rust preventive coating layer according to the present invention further comprises
The corrosion resistance is further improved by adding 1 to 500 parts by weight of fine silica. Moreover, in addition to the corrosion resistance, the drying property, the scratch resistance, and the coating film adhesion can be improved. In the present invention, finely divided silica is a generic term for silica having properties such that when dispersed in water, it has a fine particle size and can stably maintain a water-dispersed state, and semi-permanently no sedimentation is observed. It is. The finely divided silica is not particularly limited as long as it has a small amount of impurities such as sodium and is weakly alkaline. For example, "Snowtex N"
(Manufactured by Nissan Chemical Industries, Ltd.), "Adelite AT-20N"
Commercially available silica sol such as (made by Asahi Denka Kogyo KK) or commercially available Aerosil powdered silica particles can be used.

The rust preventive coating layer of the present invention contains an aqueous resin. In the present invention, the term "aqueous resin" includes not only a water-soluble resin but also a water-insoluble resin which is originally insoluble in water and in which an insoluble resin is finely dispersed in water such as an emulsion or a suspension. Examples of resins that can be used as such an aqueous resin include polyolefin resins, polyurethane resins, acrylic resins, polycarbonate resins, epoxy resins, polyester resins, alkyd resins, phenol resins, and other heat-curable resins. And the like, and a crosslinkable resin is more preferable. Particularly preferred resins are polyolefin-based resins, polyurethane-based resins, and mixed resin-based resins. The aqueous resin may be used as a mixture of two or more kinds.

The rust-preventive coating layer in the present invention comprises 100 parts by weight of an aqueous resin (including a water-soluble resin and a water-dispersible resin) as solids, 0.4 to 50 parts by weight of a thiocarbonyl group-containing compound, Preferably, the content is 0.5 to 20 parts by weight, and the silane coupling compound is 0.01 to 20 parts by weight.
Parts by weight, and optionally 0.01 to 0.01 parts by weight of a phosphate compound.
Contains 20 parts by weight. Preferably, finely divided silica is further added in an amount of 1 to 50.
0 parts by weight, preferably 100 to 400 parts by weight. Here, when the thiocarbonyl group-containing compound is less than 0.4 parts by weight, the corrosion resistance becomes insufficient. On the other hand, when it exceeds 50 parts by weight, the corrosion resistance becomes insufficient. Not only saturates and becomes uneconomical,
Depending on the aqueous resin used, the resin gels and cannot be applied. On the other hand, if the amount of the silane coupling compound is less than 0.01 part by weight, a sufficient effect of improving coating film adhesion cannot be obtained, and
If it exceeds 0 parts by weight, the film-forming properties of the coating film will be deteriorated, and as a result, the adhesion will be reduced.

Further, the phosphoric acid compound forms a phosphate layer on the surface of the metal substrate, which is used for passivation, promotes a crosslinking reaction of the resin film derived from the aqueous resin, and forms a dense rust preventive film. And rust prevention is further improved. When the content of the phosphoric acid compound is less than 0.01 part by weight, the rust-preventing effect is not sufficiently exhibited. On the other hand, when the content exceeds 20 parts by weight, the rust-preventing property is lowered or the resin is gelled. As a result, the storage stability as a rust preventive coating agent deteriorates. The content of the finely divided silica is, in the rust-proof coated steel material, from 1 to
The content is preferably 500 parts by weight. If the content is less than 1 part by weight, the effect of improving corrosion resistance is insufficient, while if it exceeds 500 parts by weight, the corrosion resistance is saturated and uneconomical.

Further, the rust preventive coating layer in the present invention may further contain other components. For example, pigments, surfactants and the like can be mentioned. Examples of the pigment include titanium oxide (TiO ₂ ) and zinc oxide (Zn).
O), zirconium oxide (ZrO), 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 O ₄ ) And various coloring pigments such as organic pigments.

The rust-proof coating layer in the present invention includes:
A solvent may be used to improve the film forming property of the aqueous resin and form a more uniform and smooth coating film. As the solvent,
There is no particular limitation as long as it is generally used for paints, and examples thereof include alcohol-based, ketone-based, ester-based, and ether-based paints.

In the present invention, the above rust-proof coating layer can be used as a rust-proof coating layer for zinc-coated steel, Al-coated steel or uncoated steel. The formation of the rust-preventive coating layer (rust-prevention treatment) may be a method in which a rust-preventive coating agent containing a predetermined component is applied to an object to be coated, and after the application, the object is heated and dried with hot air, A method may be used in which an object to be coated is heated in advance, and then a rust-preventive coating agent is hot-applied, and dried using residual heat.

The heating temperature is 50 to 250 ° C. in any of the above methods. 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 corrosion resistance and the water resistance are reduced, and the appearance is yellowed, so that it is limited to the above range. Preferably it is 70-100 degreeC. The drying time when the object to be coated is heated with hot air after application and dried is preferably 1 second to 5 minutes.

In the above rust preventive treatment, the coating thickness of the rust preventive coating layer is preferably a dry film thickness of 0.1 μm or more. If it is less than 0.1 μm, the rust-preventing ability is insufficient. On the other hand, if the dry film thickness is too thick, it is uneconomical as a coating base treatment and inconvenient for coating, so that the thickness is more preferably 0.1 to 20 μm. More preferably 0.1 to
10 μm. However, when the rust preventive coating agent is used as a water-based rust preventive paint, the film thickness may be 0.1 μm or more.

In the above rust prevention treatment, the method of applying the rust preventive coating agent is not particularly limited, and it can be applied by generally used roll coating, air spray, airless spray, immersion, or the like.

The material coated with the rust-preventive coating layer of the present invention is zinc-coated steel, Al-coated steel or uncoated steel as described above. The zinc-coated steel is specifically galvanized, zinc and Fe, Ni, Sn, C
u, P, Co, Cr, Mg, Al, Si, Mn, etc. refers to a steel material that has been subjected to alloy plating of one or two or more types. Al-coated steel is specifically Al-plated, Al and Si,
It refers to a steel material plated with an alloy of one or more of Mg, Fe, Mn, and Cu. The plating method is not particularly limited, and an electroplating method, a hot-dip plating method,
There are a vacuum plating method, a molten salt plating method, a thermal spraying method and the like. As the steel material, although not particularly limited, a cold-rolled steel sheet, a hot-rolled steel sheet,
Steel materials such as thick plates, steel bars, wires, and steel pipes may be used.

The rust-proof coated steel material of the present invention can be used not only as a base for a lubricating film or a coating base of a zinc-plated steel sheet in the field of coil coating, but also by adding a wax to a rust-proof coating layer. It can also be used for steel plates.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. Note that the present invention is not limited by these examples.

In the following examples, the corrosion resistance was evaluated by the following method. [Evaluation method] (A) Rust prevention a) Preparation of test specimen Rust prevention coating layer of the present invention (aqueous resin solid content concentration of 20)
(% By weight) was applied to a commercially available electrogalvanized steel sheet EG-MO material with a bar coat # 3 so that the dry film thickness became 1 μm, and then dried so as to have a PMT of 150 ° C.

B) SST resistance (corrosion resistance) test A 5% saline solution was sprayed on the coated surface of the object at 35 ° C.
The degree of white rust after 0 hour was evaluated on a scale of 1 to 10. Furthermore,
The evaluation was performed for both the flat part and the Erichsen 7 mm extruded part. The evaluation criteria were as follows. 10 points: No abnormality 9 points: Between 10 and 8 points 8 points: Slight white rust generated 7 to 6 points: Between 8 and 5 points 5 points: White rust generated in half of the area 4 to 2 points: Between 5 points and 1 point 1 point: White rust on the entire surface

C) Moisture resistance (warm water) test After immersion in 40 ° C. constant temperature water for 20 days, the degree of white rust was evaluated on a scale of 1 to 10. The evaluation criteria were as follows. 10 points: No abnormality 9 points: Between 10 and 8 points 8 points: Slight swelling of the coating film 7 to 6 points: Between 8 and 5 points 5 points: Swelling occurred to half of the area 4 to 2 points : Between 5 points and 1 point 1 point: Swelling occurred over the entire surface

(B) Overcoat Adhesion a) Preparation of Specimen The rust preventive coating agent of the present invention (aqueous resin solids concentration of 20
(% By weight) was applied to a commercially available electrogalvanized steel sheet EG-MO material with a bar coat # 3 so that the dry film thickness became 1 μm, and then dried so as to have a PMT of 150 ° C. After drying,
A super rack 100 (manufactured by Nippon Paint Co., Ltd .; acrylic melamine paint) was applied by a bar coat so as to have a dry film thickness of 20 μm, and then dried at 150 ° C. for 20 minutes to produce a topcoat adhesion test plate.

B) Primary Adhesion Test Crosscut: The tape peelability of a portion having a crosscut of 1 mm was evaluated, and the tape was evaluated on a scale of 10 out of the following criteria. Erichsen 7 mm: A tape was applied to the part extruded with Erichsen to 7 mm, and the tape peelability was similarly evaluated. Crosscut + Erichsen 7 mm: A tape was applied to a portion where a cut of 1 mm in crosscut was extruded with Erichsen to 7 mm, and the tape peelability was similarly evaluated. The evaluation criteria were as follows. 10 points: No abnormality 9 points: Of the measured grids, the percentage of peeling was 10% or less. 8 points: 〃 20% or less. 7 points: ３０ 30% or less. 6 points: ４０ 40% or less. 5 points: ５０ 50% or less. 4 points: ６０ 60% or less. 3 points: 〃 70% or less. 2 points: 以下 80% or less. 1 point: 〃 90% or less. 0 points: よ り Greater than 90%.

C) Secondary adhesion test After the test plate was immersed in boiling water for 30 minutes, the same test and evaluation as in the primary test were performed.

In the following Examples and Comparative Examples, the concentration expression (g / l) means the amount (g) of each component contained in 1 liter of the total amount of the aqueous resin and water. [Example 1] Polyolefin resin ("Hi-Tech S-7024", manufactured by Toho Chemical Co., Ltd.) was added to pure water so that the resin solid content concentration became 20% by weight, and 0.8 g of thiourea was further added. / L, ammonium phosphate was dissolved to a phosphate ion concentration of 1.25 g / l, and finally 25 g / l of water-dispersible silica ("Snowtex N", Nissan Chemical Industries, Ltd.) was added. 10 g of silane coupling agent
/ L, and dispersed by stirring with a disper for 30 minutes.
It adjusted so that it might be 8.0, and the rust prevention coating agent was obtained. The obtained rust-preventive coating agent was pre-heated to a sheet temperature of 80 ° C. (heating before painting).
× 1.6 mm) with a dry coat of 2-3 μm with a bar coat # 5
And dried. The hot-dip galvanized steel sheet is polished on the surface with Scotch Bright, and then an alkaline degreasing agent ("Surf Cleaner 53", manufactured by Nippon Paint Co., Ltd.)
The above evaluation was performed after degreasing, washing with water and drying. Table 1 shows the evaluation results.

Examples 2-33 Types of aqueous resins, types of thiocarbonyl group-containing compounds, and their concentrations,
Further, the procedure was performed in the same manner as in Example 1 except that the concentration of the phosphate ion and the type and amount of the silane coupling agent were changed as described in Tables 1 and 2. Tables 3 and 4 show the evaluation results.

[Comparative Examples 34 to 37] The types of the aqueous resin, the type of the thiocarbonyl group-containing compound, the concentrations thereof, the phosphate ion concentration, and the amount of the silane coupling agent used were as shown in Table 2. Except having changed, it carried out according to Example 1. Table 4 shows the evaluation results.

Comparative Example 33 A corrosion-resistant chromate comprising chromic acid and water-dispersible silica was applied at 50 mg / m ² as Cr and dried at 70 ° C. Table 4 shows the results.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

The following commercial products were used as the aqueous resins in the table: Polyolefin resin: "HITEC S-7024"
(Manufactured by Toho Chemical Co., Ltd.) However, only PC10
200) (manufactured by Shoei Chemical Co., Ltd.) Polyurethane resin: "Bon Titer HUX-320"
(Asahi Denka Co., Ltd.) Acrylic resin: "EM1220" (Nippon Paint Co., Ltd.) Epoxy resin: "Polysol 8500" (Showa Kogaku Co., Ltd.) Polyester resin: "Pesresin A-124G" (Manufactured by Takamatsu Yushi Co., Ltd.)

The silane coupling compounds in the table are represented by the following symbols. A: γ- (2-aminoethyl) aminopropyltrimethoxysilane B: γ- (2-aminoethyl) aminopropylmethyldimethoxysilane C: aminosilane D: γ-methacryloxypropyltrimethoxysilane E: N-β- ( N-vinylbenzylaminoethyl) -γ
-Aminopropyltrimethoxysilane F: γ-glycidoxypropyltrimethoxysilane G: γ-mercaptopropyltrimethoxysilane H: methyltrimethoxysilane I: vinyltriacetoxysilane J: γ-chloropropyltrimethoxysilane K: hexa Methyldisilazane L: γ-anilinopropyltrimethoxysilane M: vinyltrimethoxysilane N: octadecyldimethyl (3- (trimethoxysilyl) propyl) ammonium chloride O: γ-chloropropylmethyldimethoxysilane P: γ-mercaptopropyl Methyldimethoxysilane Q: Methyltrichlorosilane R: Dimethyldichlorosilane S: Trimethylchlorosilane

From these results, it is clear that according to the present invention, the corrosion resistance and rust resistance are remarkably improved as compared with the conventional chromate system.

[0073]

As described above, the rust-prevention-treated steel material having a thiocarbonyl group-containing compound and a silane coupling compound-based rust-preventive coating layer according to the present invention comprises a thiocarbonyl group-containing compound that is less toxic to aqueous resins. By combining a silane coupling compound effective for improving coating film adhesion, or further combining phosphate ions, or further combining these with water-dispersible silica, the conventional chromate-containing aqueous resin-based rust preventive Demonstrates better rust prevention than steel with layers. Therefore, it is possible to provide a chromium-free rust-proof coated steel material having low pollution and excellent rust-preventive ability. Further, the rust-preventive treatment steel material coated with a rust-preventive coating layer containing a thiocarbonyl group-containing compound and a silane coupling compound-based rust-preventive coating agent according to the present invention, or a phosphate ion, or further, water-dispersible silica is added thereto. Since a film having excellent rust prevention ability is formed for the same reason as described above, generation of rust can be suppressed.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) C23F 11/00 C23F 11/00 B (72) Inventor Yujiro Miyauchi 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Kimitsu Inside Steel Works (72) Inventor Atsushi Morishita 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside Nippon Steel Corporation (72) Inventor Hiroshi Kanai 20-1 Shintomi, Futtsu City, Chiba Prefecture Technology Development of Nippon Steel Corporation Inside the headquarters (72) Inventor Toshiaki Shimakura 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. (72) Inventor Katsuyoshi Yamazoe 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd.

Claims (3)

[Claims] 1. An organic resin 1 as a solid content on a surface layer of zinc-based metal-coated steel, aluminum-coated steel, or uncoated steel.
A rust-proof coated steel material comprising a rust-proof coating layer comprising 00 parts by weight, 0.4 to 50 parts by weight of a thiocarbonyl group-containing compound, and 0.01 to 20 parts by weight of a silane coupling compound. 2. The rust-proof coated steel material according to claim 1, wherein said rust-proof coating layer contains 0.01 to 20 parts by weight of a phosphoric acid compound. 3. The anti-corrosion coating layer according to claim 1, wherein the anti-rust coating layer has a thickness of 1 to 500.
The rust-proof coated steel material according to claim 1 or 2, further comprising a part by weight of fine silica.