JP2000234176A - Chromium-free organically coated galvanized steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive non-chromium rust preventive coating agent having corrosion resistance equal to or above that of a chromium-contg. rust preventive agent, to provide a rust prevention treating method and to provide rust prevention-treated steel. SOLUTION: This chromium-free organically coated galvanized steel is the one in which the orientation index in the (101) face of zinc crystals in the galvanizing face on the surface of a steel sheet is >=0.5, the plating surface layer is provided with an organic resin coating film layer formed by a coating material consisting essentially of a water base resin by 0.2 to 10.0 μm, and, moreover, the coating material contains, in 1 l of the compsn. consisting essentially of a water base resin and water, 0.2 to 50 g thiocarbonyl group-contg.compd. as indispensable components and one or >= two kinds among 0.1 to 5 g phosphate ions, 0.1 to 20 g vanadic acid compd. and 5 to 300 g water dispersible silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant surface-treated steel material having an organic resin film on the outermost layer, which is widely used for home appliances, computer-related equipment, building materials, and industrial products such as automobiles.

[0002]

2. Description of the Related Art Galvanized steel and alloyed galvanized steel produce white rust on the surface and significantly impair the appearance not only in an atmosphere containing salt such as seawater, in a high-temperature and high-humidity environment, but also in a normal indoor environment. Also, the rust-preventing force on the base steel surface is reduced. In order to prevent white rust, chromate-based rust preventive materials have been frequently used.
No. 370 discloses a resin-based rust preventive in which an olefin-α, β-ethylenically unsaturated carboxylic acid copolymer resin dispersion contains a water-dispersible chromium compound and water-dispersible silica.

However, even the above-mentioned chromium-containing resin treating agent does not always have sufficient corrosion resistance, and white rust occurs when exposed to salt water or a high-temperature and high-humidity atmosphere for a long time. In addition, since a chromium compound has a high risk of harmful effects on the human body, in recent years, a demand for a chromium-free rust preventive agent has been increasing. The inventors have found that a sulfide ion reacts with zinc to form a stable ZnS film, and has already disclosed in JP-A-8-239776 and JP-A-8-67834 that non-chromium containing sulfide or sulfur is used. A rust preventive agent is disclosed.

[0004] However, some of the sulfides emit a peculiar odor, and handling is not always easy. Further, a rust inhibitor using a triazine thiol compound containing a sulfur atom and having no odor or toxicity has been proposed.
For example, "Aqueous anticorrosion paint" of JP-A-53-31737 discloses an aqueous anticorrosion paint to which a diol-S-triazine derivative is added.

Japanese Unexamined Patent Publication (Kokai) No. 61-222302 discloses a "reactive emulsion with metal" as a reactive emulsion of a compound obtained by mixing a thiocarbonyl group-containing compound with a water-insoluble organic compound. Is disclosed. However, the water-based anticorrosion paint disclosed in the above-mentioned JP-A-53-31737 is adjusted to be more easily adhered to mild steel or brass. Therefore, it was insufficient as a rust inhibitor for metal surfaces such as zinc.

[0006] The reactive emulsion disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-222302 is also made of copper, nickel,
Since it is an emulsion that reacts with tin, cobalt, aluminum and the like and alloys thereof, it is not sufficient as a rust inhibitor for metal surfaces such as zinc. The present inventors have researched a triazinethiol-containing rust-preventive coating agent which is also effective for rust-prevention of galvanized steel, and disclosed a triazinethiol-containing rust-preventive coating agent described in JP-A-9-2557. However, triazine thiol is an expensive compound, and a less expensive rust inhibitor has been desired.

[0007] 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. JP-A-54-71734 discloses that two or six condensed phosphates of myo-inositol or salts thereof are 0.5 to 100 g / l and one or two selected from the group consisting of titanium fluoride and zirconium fluoride. A method for surface-treating zinc or a zinc alloy, wherein the surface of the zinc or zinc alloy is 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. It is. This technology is
In order to form a passivation film as a protective layer on the surface of zinc, titanium fluoride or zirconium fluoride is required. Also, Japanese Patent Application Laid-Open No. 3-226584 discloses N
Disclosed is a surface treatment agent which is an aqueous solution of at least 0.02 g / l of i ²⁺ and Co ²⁺ and one or two of compounds having ammonia and a primary amine group and having a pH of 5 to 10 are doing. 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 treating agent containing a metal ion has disadvantages such as an increase in load during wastewater treatment.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an inexpensive, non-chromium-free zinc or zinc alloy-plated steel material having corrosion resistance higher than that of a chromium-containing rust inhibitor. is there.

[0009]

In order to achieve the above-mentioned object, in order to achieve the above-mentioned object, the orientation index of the (10.1) plane of the zinc crystal on the galvanized surface of the steel material is 0.5 or more, and an aqueous resin Having an organic resin coating layer formed of a coating mainly composed of 0.2 μm to 10.0 μm, and wherein the coating contains 0.2 to 1 μl of a composition mainly composed of an aqueous resin and water. 50 g of a thiocarbonyl group-containing compound as an essential component, 0.1 to 5 g of a phosphate ion, 0.1 to 20 g of a vanadate compound and
It is characterized by containing one or more kinds of 300 g of water-dispersible silica, and is obtained by applying this coating material to a galvanized surface having a crystal orientation index defined as described above. Provide plated steel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, in order to be effective as a rust preventive coating agent, it is necessary to (1) prevent penetration of a corrosive liquid and (2) to have an adhesive property of a rust preventive film to a 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 inhibitor was mainly excellent in passivation. Here, the passivation means that a metal or an alloy is in a state of maintaining inertness despite being an environment capable of being activated chemically or electrochemically.

Sulfides, like chromic acid, are easily adsorbed on the metal surface and have excellent oxidizing ability, so that the metal surface can be passivated. Accordingly, the thiocarbonyl group-containing compound, which is one of the oxides, has an effect of preventing white rust of zinc plating. When a vanadium compound is added to such a rust preventive, the following rust preventive action of vanadate ions is added, and the rust preventive effect is further promoted.

The vanadium compound is ionized and dissolved in the rust preventive agent, or the vanadium compound is dissolved in the ion as an ion depending on the compound and the amount added, and is 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 vanadium 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 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 the thiocarbonyl group-containing compound is added together with phosphate ions, its rust-preventing effect 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,
(1) It is presumed that ions of the thiol group in the thiocarbonyl group-containing compound are adsorbed to sites on the zinc surface during the application of the rust-preventive coating agent, thereby exhibiting a rust-preventive effect.
Naturally, a sulfur atom easily forms a coordination bond with zinc, but a thiocarbonyl group (formula 1)

[0015]

Embedded image Having the formula (2)

[0016]

Embedded image It is more preferable that the compound has both nitrogen and oxygen atoms. In these compounds, since a nitrogen atom and an oxygen atom can also form a coordinate bond with zinc, a thiocarbonyl compound having these atoms at the same time easily forms a chelate bond on the zinc surface, and the thiocarbonyl compound It is possible to firmly adsorb on the zinc surface. Sites on inert zinc surfaces (eg oxide surfaces)
Does not adsorb a thiocarbonyl group-containing compound, but phosphate ions act on such an inactive surface to form zinc phosphate and 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.

Notably, in addition to the excellent rust-preventive action of the above-mentioned thiocarbonyl group-containing compound and phosphate ions and vanadate ions, 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 agent found in the present invention is extremely effective in achieving passivation of the metal surface by rust preventive ions and the like. However, zinc metal belongs to a close-packed hexagonal system when crystallographically classified, and it is known that a close-packed plane, that is, a (00 · 2) plane is a chemically stable plane, that is, an inactive plane. When zinc plating is manufactured by the usual electroplating method, the (00 ・ 2) face or (10 ・ 1)
It is common that the surface, the (11.1) surface and the like are mixed, and it is known that the abundance ratio changes depending on plating conditions. Therefore, the present inventors prepared galvanized steel materials having different crystal orientation planes, prepared samples in which an organic resin coating was applied to the surface layer under the same conditions, and investigated the relationship between corrosion resistance and crystal orientation. As a result, it has been found that the larger the orientation index of the (10 · 1) plane, the higher the corrosion resistance, and it is desirable that the orientation index is at least 0.5 or more. Although the mechanism of action is not completely clear, the (10 · 1) plane is called a Pyramidel plane (pyramidal plane) and the high index plane faces the plating surface direction. , Holes and the like are present in an extremely large number as compared with the (00 · 2) plane. Such an active surface acts as a strong adsorption site for the rust preventive agent (thiocarbonyl compound, phosphate ion, vanadate ion) found in the present invention, so that the rust preventive action is strongly exerted. It is estimated to be.

The calculation of the orientation index of the zinc crystal plane was performed according to the following method. Let the intensity of the diffraction peak of each crystal plane (hk · l) obtained by measuring the galvanized steel material by the X-ray diffraction method be I (hk · l). Further, the intensity of the diffraction peak when using the standard zinc powder is Is (hk
· L) (the subscript s stands for standard)
ard). This is the crystal face of interest (10.
1) The orientation index CI (10.1) of the plane is defined by the following formula (CI is Crystallographic I
ndex).

[0020]

(Equation 1) Where I = I (10 · 1) / ｛I (002) + I (100) +
I (101) + I (102) + I (103) + I (00
4) + I (112) + I (201) + I (104) + I
(202)｝ Is = Is (10 · 1) / ｛Is (002) + Is (1
00) + Is (101) + Is (102) + Is (10
3) + Is (004) + Is (112) + Is (20
1) + Is (104) + Is (202)｝ That is, the zinc crystal plane of the electrogalvanized layer (10 · 1)
The orientation index of the plane is the relative value of the diffraction intensity of the (10 · 1) plane with respect to the sum of the diffraction intensities of the respective crystal planes of the galvanized layer, which is the same relative value of the (10 · 1) plane in the case of zinc powder. This shows the deviation from the value in the case of zinc powder. Therefore, CI (10 · 1) is 1
When it is larger, it indicates that the (10.1) plane exists preferentially as compared with the case of zinc powder (random mixing).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the thiocarbonyl group-containing compound according to the present invention will be described in detail. In the present invention, the thiocarbonyl group-containing compound refers to a thiocarbonyl group (1)

[0022]

Embedded image And compounds capable of releasing a thiocarbonyl group-containing compound in an aqueous solution or in the presence of an acid or alkali. A typical example of the thiocarbonyl group-containing compound is represented by the formula (3)

[0023]

Embedded image Such as methylthiourea, dimethylthiourea, ethylthiourea, diethylthiourea, diphenylthiourea, thiopental, thiocarbazide, thiocarbazones, thiocyanuric acids,
Thiohydantoin, 2-thiouramil, 3-thiourazole and the like; Formula (4)

[0024]

Embedded image A thioamide compound represented by, for example, thioformaldehyde, thiocarbostyril, thiosaccharin, etc .;

[0025]

Embedded image A thioaldehyde compound represented by, for example, thioformaldehyde, thioacetaldehyde, etc .;

[0026]

Embedded image Carbothios represented by, for example, thioacetic acid, thiobenzoic acid, dithioacetic acid, etc .;

[0027]

Embedded image And other compounds having the structure of formula (1), for example, thiocoumazone, thiocumothiazone, thionin blue J, thiopyrone, thiopyrine, thiobenzophenone and the like.

Among the above, those which do not directly dissolve in water are once dissolved in an alkaline solution and then blended into a paint. Here, when the thiocarbonyl group-containing compound is less than 0.2 g / l, the corrosion resistance becomes insufficient. On the other hand, when it exceeds 50 g / l, the corrosion resistance becomes saturated and uneconomical, and the aqueous resin used In some cases, the resin gels and cannot be applied. Therefore, the upper limit is set to 50 g / l.

When the amount of the vanadate compound is less than 0.1 g / l, the corrosion resistance becomes insufficient. On the other hand, when the amount exceeds 20 g / l, not only is the corrosion resistance saturated and uneconomical,
Depending on the aqueous resin used, the resin gels and cannot be applied, so it is preferably 10 g / l or less. Therefore, the upper limit is set to 20 g / l. Vanadate compounds are vanadates such as vanadate, ammonium vanadate, sodium vanadate, potassium vanadate, strontium vanadate, sodium hydrogen vanadate,
Further, it can be supplied in the form of a phosphovanadate such as vanadate or ammonium phosphovanadate.

Phosphate ions form a phosphate layer on the metal substrate, passivate it, remarkably improve the adhesion between the resin layer and the substrate, and promote the crosslinking reaction of the resin film derived from the aqueous resin. As a result, a dense rust prevention film is formed, so that the rust prevention property is further improved. When the content of phosphate ions is less than 0.1 g / l, the rust-preventing effect is not sufficiently exerted. On the other hand, when the content exceeds 5 g / l, not only does the corrosion resistance become saturated and uneconomical, but also the resin becomes uneconomical. When added to the contained aqueous solution, the resin gels depending on the aqueous resin and cannot be applied. Therefore, the upper limit is set to 5 g / l.

In the paint according to the invention, furthermore the total composition 1
Addition of 5 to 300 g / l of water-dispersible silica per liter further improves the corrosion resistance. 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, the water-dispersed silica is a generic term for silica having properties such that it has a fine particle size, maintains a stable state when dispersed in water, and has no semipermanent sedimentation. . The water-dispersible 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), "Adelite AT-
Commercially available silica gel such as "20N" (manufactured by Asahi Denka Kogyo KK), or commercially available Aerosil powdered silica particles can be used.

The content of the water-dispersible silica is preferably 5 to 300 g / l in 1 liter of the coating material, and if the content is less than 5 g, the effect of improving corrosion resistance is insufficient. On the other hand, if it exceeds 300 g, the corrosion resistance becomes saturated and uneconomical. 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 of both. The aqueous resin may be used as a mixture of two or more kinds.

The coating material containing the resin according to the present invention is a composition in which an aqueous resin (including a water-soluble resin and a water-dispersible resin) has a solid content of 1 to 80 parts by weight and 99 to 20 parts of water as a main component. And the thiocarbonyl group-containing compound is contained in an amount of 0.2 to 50 g, preferably 0.5 to 20 g, per liter of the composition.
g and the vanadate compound in an amount of 0.1 to 20 g, preferably 0.5 to 10 g, and more preferably 0.1 to 5 g, preferably 0.1 to 3 g, and / or aqueous dispersion of phosphate ions. 5 to 300 g of silica, preferably 1
It contains 0-150 g.

Further, the resin-based paint according to 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 hydrolytic condensate thereof to improve the affinity between the aqueous resin and the silica particles and the pigment, and further to improve the adhesion between the aqueous resin and the zinc or iron phosphate layer, or You may mix | blend both of them. Here, "hydrolysis condensate of a silane coupling agent"
It refers to an oligomer of a silane coupling agent obtained by subjecting a silane coupling agent to hydrolysis and polymerization using a silane coupling agent as a raw material.

As the above pigment, for example, titanium oxide (T
iO ₂ ), zinc oxide (ZnO), zirconium oxide (Z
rO), 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.
It is used at a concentration of from 02 to 20 g, preferably from 0.1 to 2.5 g. If 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 20 g, the storage stability is lowered, which is not preferable.

A solvent may be used in the resin-containing paint according to the present invention 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 examples thereof include alcohol-based, ketone-based, ester-based, and ether-based solvents. In the present invention, the above coating material can be used as an organic resin coating agent for zinc-coated steel or uncoated steel to perform rust-proofing treatment on zinc-coated steel or uncoated steel. The rust prevention treatment may be a method in which a rust prevention paint containing a resin is applied to an object to be coated, and after the application, the object to be coated is heated and dried with hot air.

The 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, 250
If the temperature exceeds ℃, in the case of a system containing a resin, thermal decomposition of the aqueous resin occurs, so that the salt spray resistance and the water resistance are reduced, and the appearance is yellowed, so that it is limited to the above range. 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 rust preventive treatment, the coating thickness of the rust preventive paint of the present invention is desirably a dry film thickness of 0.2 μm or more. If it is less than 0.2 μm, 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 and it is uneconomical, so that the thickness is preferably 10 μm or less, more preferably 0.4 to 5 μm. The coating method is not particularly limited, and a commonly used roll coat,
It can be applied by air spray, airless spray, immersion, or the like. After the application, the object to be coated is heated in a hot air oven, a direct fire oven, an IH oven, or the like, and dried.

The material coated with the rust preventive paint of the present invention is, as described above, electrogalvanized steel. The galvanized steel is specifically galvanized, zinc and trace amounts of Fe, Ni, Co, Cr, Mg, Al, Si, M
It refers to a steel material that has been subjected to alloy plating of one or more of n and the like, and may be a material having an η layer that is a zinc crystal system. The plating solution composition is not particularly limited, and a sulfate bath, a chloride bath, a cyan bath, a mixed bath thereof,
There is a molten salt bath. Further, if the crystal orientation of the present invention can be obtained, it is not necessary to limit to the electroplating method, and any of a hot-dip plating method and a vacuum plating method may be used. The steel material is not particularly limited, but may be a steel material such as a cold rolled steel plate, a hot rolled steel plate, a thick plate, a steel bar, a steel pipe, or the like.

Further, by adding a wax to the coating containing the resin of the present invention, it can be used as a lubricating rust preventive for lubricating steel sheets. In the following examples, the corrosion resistance was evaluated by the following method. [Evaluation method] (A) Rust prevention a) Preparation of specimens A plated steel sheet in which the orientation of zinc crystals was changed by changing various plating conditions was prepared, and a system containing the resin of the present invention was further prepared. Paint with bar coat # 3 and dry film thickness of 1
After coating to a thickness of μm, it was dried to a PMT of 150 ° C.

B) Salt Spray Test A test method in accordance with JIS Z2371 (5% saline was sprayed on the surface of the object to be coated at 35 ° C., and the degree of white rust after 240 hours was evaluated on a scale of 1 to 10. Is a flat part and Eriksen 7
This was performed for both the mm extruded portions. The evaluation criteria were as follows.

10 points: no abnormality 9 points: between 10 points and 8 points 8 points: slight white rust generation 7 points to 6 points: between 8 points and 5 points 5 points: white rust generation in half of the area 4 ~ 2 points: between 5 points and 1 point 1 point: white rust occurred on the entire surface (B) Top coat adhesion a) Preparation of test specimen A coating containing the resin of the present invention was dried with a bar coat # 3. Is applied to be 1 μm, and then PMT150
It dried so that it might be set to ° C. After drying, Super Rack 1
00 (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 a PMT of 150 ° C. for 20 minutes to produce a top coat 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 a portion extruded with Erichsen to 7 mm, and the tape peelability was similarly evaluated.

Cross-cut + Erichsen 7 mm: A tape with a cut of 1 mm in cross-section was extruded to 7 mm with Erichsen, and a tape was applied thereto. The evaluation criteria were as follows. 10 points: No abnormality 9 points: The percentage of peeling out of the grids measured was 10% or less 8 points: ２０ 20% or less 7 points: ３０ 30% or less 6 points: ４０ 40% or less 5 points: ５０ 50% or less 4 Points: 〃60% or less 3 points: ７０70% or less 2 points: 〃80% or less 1 point: ９０90% or less 0 points: 大 Greater than 90% c) Secondary adhesion test Immerse the test plate in boiling water for 30 minutes Thereafter, the same test and evaluation as the temporary test were performed.

D) Measurement of Orientation Index of Plated Crystals The plated steel sheet was measured by an X-ray diffraction method, the intensity of the peak attributed to each crystal plane was measured, and (10 · 1 ) The orientation index of the plane was determined.

[0049]

The present invention will be described below in detail with reference to examples. In Examples and Comparative Examples, the concentration expression (g / l) means the content weight (g) of each component contained in 1 liter of the rust preventive coating composition. <Example 1> A polyolefin resin "Hi-Tech S-7024" (trade name; manufactured by Toho Chemical Co., Ltd.) and a polyurethane resin "Bon Titer HUX-320" (trade name; manufactured by Asahi Denka Co., Ltd.) were added to pure water. The total concentration of resin solids is 20
1: 1 (weight ratio) of solid content in a ratio of 1% by weight (weight ratio) and 10 g of ammonium vanadate
/ L, thiourea 0.2 g / l, phosphate ion 2.5 g
g / l, and finally 200 g / l of water-dispersible silica “Snowtex-N” (trade name, manufactured by Nissan Chemical Industries, solid content concentration: 20%) was added, and then 30 g by a disper.
After stirring and dispersing for minutes, the coating composition of the present invention was obtained by adjusting the pH to 8.0. In order to evaluate the obtained paint for primary rust prevention and top coat adhesion, an electrogalvanized steel sheet (70 × 15) having a (10 · 1) plane crystal plane orientation index of 1.1 was used.
(0 × 0.8 mm) and dried. An electrogalvanized steel sheet is prepared from a sulfate bath by an electroplating method, and the orientation index is controlled by controlling the current density, liquid stirring strength, pH, temperature, and supporting electrolyte concentration (Na ₂ O ₄ , (NH ₄ ) ₂ SO ₄ ). , Etc.).

The base steel sheet was degreased with an alkali degreasing agent ("Surf Cleaner 53", manufactured by Nippon Paint Co., Ltd.) before painting, washed with water, and dried, and then evaluated as described above. Table 1 shows the evaluation results.
It was shown to. <Examples 2 to 10> In Example 1, the addition amount and type of the thiocarbonyl group-containing compound in the paint, the addition amount of phosphate ion, the addition amount of Snowtex-N, and the addition amount and type of the vanadate compound were determined. An antigalvanized steel sheet was obtained in the same manner as in Example 1 except that each was changed as described in Table 1, and the rustproofness and the adhesion of the topcoat were evaluated in the same manner. Table 1 shows the evaluation results. <Examples 11 to 20> Except that in Example 1, the addition of the vanadium compound in the paint was stopped (except for Example 13), and the amount and type of the silane coupling agent were changed as shown in Table 2. In the same manner as in Example 1, a galvanized steel sheet subjected to a rust-proof treatment was obtained, and the rust-proof property and the adhesion of the overcoat were evaluated in the same manner. The results are shown in Table 2. <Examples 21 to 25> Electric zinc treated in the same manner as in Example 1 except that a galvanized steel sheet in which the orientation index of the galvanized layer was changed from 0.5 to 7.5 was produced. A plated steel sheet was obtained, and the rust prevention property and the top coat adhesion were evaluated in the same manner. Table 3 shows the evaluation results. <Comparative Example 26> An electrogalvanized steel sheet was treated in the same manner as in Example 1, except that the addition amount of thiourea was changed to 0.1 g / l in the composition of the paint. This was evaluated after polishing, degreasing, washing with water and drying in the same manner as in Example 1. Table 3 shows the results. <Comparative Example 27> An electroplated steel sheet was treated in the same manner as in Comparative Example 26, except that the amount of phosphate ions in the paint was as shown in Table 3. This was evaluated after polishing, degreasing, washing with water and drying in the same manner as in Example 1. Table 3 shows the results. <Comparative Example 28> An electroplated steel sheet was treated in the same manner as in Comparative Example 26 except that the amount of Snowtex-N in the paint was as shown in Table 3. This was evaluated after polishing, degreasing, washing with water and drying in the same manner as in Example 1. Table 3 shows the results. <Comparative Example 29> An electroplated steel sheet was treated in the same manner as in Comparative Example 26 except that the amount of ammonium vanadate in the paint was changed as shown in Table 3. This was evaluated after polishing, degreasing, washing with water and drying in the same manner as in Example 1. Table 3 shows the results. <Comparative Examples 30 to 32> Electric zinc treated in the same manner as in Example 1 except that a galvanized steel sheet in which the orientation index of the galvanized layer was changed from 0.1 to 0.4 was produced. A plated steel sheet was obtained, and the rust prevention property and the top coat adhesion were evaluated in the same manner. Table 3 shows the evaluation results.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

As described above, the present invention is applied to a galvanized steel material obtained by controlling the crystal orientation of the galvanized layer of the galvanized steel material so that the (10.1) plane of zinc has an orientation index of 0.5 or more. The present invention provides an anti-corrosion paint comprising, as a main component, water and a water-soluble resin, a thiocarbonyl group-containing compound and a vanadate compound, and further a phosphate ion and / or water-dispersible silica. The rust-treated material exhibits more excellent rust-proofing properties than conventional chromate-containing aqueous resin-based rust-proof plated materials. All components used in the rust-preventive coating agent of the present invention have low toxicity,
Therefore, it is possible to provide a chromium-free rust-proofing plated steel material having low pollution and excellent rust-preventive ability.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C25D 5/48 C25D 5/48 (72) Inventor Yujiro Miyauchi 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Kimitsu Corporation Inside the steelworks (72) Atsushi Morishita, 1 at Kimitsu, Kimitsu-shi, Chiba Prefecture Within Kimitsu Works, Nippon Steel Corporation (72) Inventor, Toshiaki Shimakura 19-17, Ikedanakamachi, Neyagawa-shi, Osaka Nippon Paint Corporation

Claims (1)

[Claims] 1. An organic resin film formed by coating a coating mainly composed of an aqueous resin on a plating surface layer, wherein a zinc crystal has a (10.1) plane orientation index of 0.5 or more on a galvanized surface of a steel material. The coating has a layer of 0.2 μm to 10.0 μm, and the above coating material contains 0.2 to 50 g of a thiocarbonyl group-containing compound as an essential component in 1 liter of a composition mainly composed of an aqueous resin and water. 1-5 g of phosphate ions, 0.1-20 g of vanadate compound and 5-30
A chromium-free organic-coated galvanized steel material containing one or more kinds of water-dispersible silica of 0 g.