JPH10195344A - Rust-proofing coating agent containing telluric acid, method for rust-proofing and rust-proofed metallic metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-chromic rust-proofing coating agent having rust- proofing properties superior to those of a chromium-containing rust-proofing agent by adding tellurate ions to a composition based on a water-based resin and water, to provide a method for rust-proofing and to provide a rust-proofed metal material treated with a non-chromic rust-proofing agent and having excellent rust-proofness. SOLUTION: Examples of the sources of tellurate ions include telluric acid (H6 TeO6 ), potassium hydrogentellurate (K2 H4 TeO6 ), sodium hydrogentellurate (Na2 H4 TeO6 ), potassium tellurate (K2 TeO4 ), and sodium tellurate (Na2 TeO4 ). Among them, telluric acid is desirable. The water-based resin is desirably a heat-curable cross-linkable resin such as a polyolefin resin, a polyurethane resin or an acrylic resin. 0.5-50g/L of tellurate ions are added to a coating agent comprising 1-80 pts.wt. (in terms of the solid content) water-based resin and 99-20 pts.wt. water, the pH of the resulting mixture is adjusted to 3-12, and phosphate ions, water-dispersible silica, etc., are added to the mixture to obtain a rust-proofing coating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rust-preventive coating agent containing telluric acid, a rust-preventive treatment method, and a rust-preventive metal material, in particular, a chromium-free rust-preventive coating agent and a rust-preventive treatment which surpass the rust-preventing ability of a chromium-containing rust-preventive agent. The present invention relates to a method and a rust-proof metal material.

[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 agent does not always have sufficient corrosion resistance, and white rust is generated when exposed to a salt water or high-temperature and high-humidity atmosphere for a long time. In recent years, the toxicity of chromium has been clarified, and its use in devices and places where an object to be coated is in direct contact with the human body has been restricted.

Accordingly, in recent years, there has been an increasing demand for non-chromium rust preventive agents. For example, Japanese Patent Publication No. 57-61824
Publication "Cold rolled steel sheet with excellent temporary rust prevention and paintability"
Has a surface area of 0.01 to ²⁰ per square meter of steel sheet.
Ti distributed at a rate of 0 mg as well as 0.1 per m ² .
Pb, Te, Be, distributed at a rate of 01 to 200 mg
Disclosed is a cold-rolled steel sheet having an ultra-thin coating layer mainly composed of one or more members selected from the group consisting of Ce, In, Zr, Tl, and Sn and having excellent temporary rust prevention and coating properties. ing.

Japanese Unexamined Patent Publication (Kokai) No. 3-94074 discloses an "improved composition for applying a coating to a metal surface and a method for applying the same" to improve the corrosion resistance of the iron phosphate method and to increase the cost and complexity of the method. In order to improve the zinc phosphate method, compositions comprising water, acids, phosphate ions, oxidizing agents, tellurium ions and / or selenium ions have been proposed.

[0007]

However, the method for rust-proofing a cold-rolled steel sheet disclosed in Japanese Patent Publication No. Sho 57-61824 discloses a method for coating a Ti compound with Pb, Te, Be, and C.
e, In, Zr, Tl and Sn, after applying an aqueous solution or suspension containing at least one compound selected from the group consisting of compounds, and then reducing or inert non-oxidizing. By performing recrystallization annealing in an atmosphere, an extremely thin film is formed on the surface of the steel sheet. For this reason, the treatment method is complicated, and since it aims at temporary rust prevention, it cannot be used as a white rust rust preventive for galvanized steel sheets.

[0008] The above method is intended for temporary rust prevention of cold rolled steel sheets, and cannot be used for white rust prevention of galvanized surfaces.

[0009] Further, using the improved composition for coating application disclosed in the above-mentioned JP-A-3-94074,
Only corrosion resistance comparable to that of zinc phosphate treatment was obtained, which was insufficient compared with the recent requirements for corrosion resistance.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a chromium-free rust-preventive coating agent having a corrosion resistance higher than that of a chromium-containing rust-preventive agent, and a rust-preventive treatment method. Another object of the present invention is to provide a rust-proofing metal material which is non-chromium-free and has excellent corrosion resistance.

[0011]

In order to achieve the above object, the telluric acid-containing rust preventive coating agent according to the present invention is used in an aqueous resin and a composition containing water as a main component in an amount of 0.5 to 0.5%.
Contains 50 g / l of tellurate ion.

Further, the rust preventive treatment method according to the present invention is a treatment method in which zinc-coated steel or uncoated steel is coated with the rust-preventive coating agent.

Further, the rust-proofing metal material according to the present invention is a metal material coated with the rust-preventive coating agent.

In general, in order to be effective as a rust-preventive coating agent, it is necessary to (1) prevent penetration of a corrosive solution;
(2) Adhesion of the rust prevention film to the metal substrate, (3) Passivation of the metal surface by rust prevention ions, etc., (4)
It is necessary to satisfy that the rust prevention film has 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 preventive was excellent mainly 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 an environment where it is chemically or electrochemically activated.

[0015] telluric acid ion (TeO ₆ ^6- or TeO
₄ ^2- ) has an oxo acid structure like the chromate ion, is easily adsorbed on the metal surface, and has excellent oxidizing ability, so that the metal surface can be passivated. Therefore, tellurate ions have an effect of preventing white rust in galvanizing. It is known that tellurium ions contained in the above rust preventive agent are less likely to be passivated than tellurate ions.

Further, when the tellurate ion is added to a rust-preventive coating agent containing an aqueous resin, its rust-preventing effect is remarkably improved. That is, the tellurate ions in the rust-preventive coating agent react with the base metal at the time of applying the rust-preventive coating agent and passivate as described above, and the tellurate ions are derived from the aqueous resin formed on the surface of the metal base material. Since it remains on the resin film and acts as a crosslinking accelerator, the curing of the resin is enhanced, and as a result, a dense rust-preventive film is formed on the surface of the metal substrate. Further, by forming a dense rust preventive film, it is possible to block the penetration of harmful ions such as moisture and chlorine ions, so that the rust preventive effect is significantly higher than that of the chromium-containing rust preventive.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

First, the telluric acid-containing rust preventive coating agent according to the present invention will be described in detail.

Sources of tellurate ions include telluric acid (H ₆ TeO ₆ ) and potassium hydrogen tellurate (K ₂ H ₄ T).
eO ₆ ), potassium tellurate (K ₂ TeO ₄ ), sodium hydrogen tellurate (Na ₂ H ₄ TeO ₆ ), sodium tellurite (Na ₂ TeO ₄ ), or sodium tellurite (Na ₂ TeO ₃ ), Potassium tellurate (K ₂ Te
O ₃ ) and the like, but sodium ions and the like may cause blisters and the like if they remain in the resin film. Therefore, telluric acid (H ₆ TeO ₆ ) is more preferable.

As a supply source of the aqueous resin, any resin can be used as long as it is aqueous. For example, a polyolefin resin, a polyurethane resin, an acrylic resin, a polycarbonate resin, a polyester resin, an alkyd resin, a phenol resin, other heat-curable resins, and the like are crosslinkable resins. Is more preferable. Further, the above-mentioned aqueous resin may be mixed at an arbitrary ratio, or two or more resins may be mixed.

The rust-preventive coating agent according to the present invention contains an aqueous resin (including a water-soluble resin and a water-dispersible resin) in a solid content of 1%.
８０80 parts by weight, water 99 部 20 parts by weight, and further containing 0.5 to 50 g / l, preferably 2 to 20 g / l of tellurate ions with respect to the coating agent, and the pH is adjusted to a range of 3 to 12. ing. Here, tellurate ion is 0.5 g /
l, the corrosion resistance becomes insufficient, while 50 g
If it exceeds / l, not only does the corrosion resistance become saturated and uneconomical, but also depending on the aqueous resin used, the resin gels and cannot be applied.

Further, the rust preventive coating agent according to the present invention may contain a rust preventive additive. Examples of the antirust additive include phosphate ions, water-dispersible silica, and the like.

The content of phosphate ions in the rust preventive coating agent is preferably 0.1 to 5 g / l. The phosphate ions form and passivate a phosphate layer on the surface of the metal substrate. Further, since the crosslinking reaction of the resin film derived from the aqueous resin is promoted to form a dense rust prevention film, rust prevention properties are further improved. When the content of the phosphate ion is less than 0.1 g / l, the rust-preventing effect due to the addition of the phosphate ion is not sufficiently exhibited.
As the resin gels, the storage stability of the rust preventive coating agent as a product deteriorates.

By adding water-dispersible silica to the rust preventive coating agent according to the present invention, it is possible to improve the drying property, scratch resistance and coating film adhesion. 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, Ltd.), “Adelite A”
Commercially available silica gel of "T-20N" (manufactured by Asahi Denka Kogyo KK),
Alternatively, commercially available aerosil powdered silica particles or the like can be used. The content of the water-dispersible silica is preferably 0.1 to 30 parts by weight based on 100 parts by weight of the aqueous resin solid content. When the content of the water-dispersible silica is less than 0.1 part by weight, the rust-preventing effect is not sufficiently exhibited, while when it exceeds 30 parts by weight, the rust-preventing property is reduced.

Further, the rust preventive coating agent according to the present invention may further contain other components. For example, pigments, surfactants and the like can be mentioned. In addition, silica particles as an aqueous resin, to improve the affinity of the pigment, further to improve the adhesion between the aqueous resin and the zinc or iron phosphate layer, even if a silane coupling agent is blended. Good.

Examples of the pigment include 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 various coloring pigments such as organic pigments can be used.

Examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, N- [ 2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane.

A solvent may be used in the rust preventive coating agent 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 coating materials, and examples thereof include alcohol-based, ketone-based, ester-based, and ether-based solvents.

In the present invention, the above-mentioned rust-preventive coating agent can be used as a rust-preventive coating agent for zinc-coated steel or uncoated steel to perform rust-prevention treatment on zinc-coated steel or uncoated steel. The rust-prevention treatment may be a method of applying the rust-preventive coating agent of the present invention to an object to be coated, heating the object to be coated with hot air after application, and drying the object. A method may be used in which the rust-preventive coating agent of the present invention 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 SST property and the water resistance are reduced, and the appearance is yellowed. 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 rust-preventive treatment, the coating thickness of the rust-preventive coating agent of the present invention 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, it is 0.1 to 10 μm.

In the above-mentioned prevention treatment, the method of applying the rust preventive coating agent of the present invention 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 agent of the present invention is zinc-coated steel or uncoated steel as described above.

The rust preventive coating agent of the present invention can be used as a so-called primary rust preventive agent, and can also be used as a coating base treating agent. Further, the film thickness is 10 to 50 μm
By doing so, it can also function as a paint having an antirust effect.

Further, another preferred embodiment of the present invention will be described below.

1. The source of telluric acid ions in the telluric acid-containing rust preventive coating agent is telluric acid (H ₆ TeO
₆ ), sodium hydrogen tellurate (Na ₂ H ₄ Te)
O ₆ ), potassium hydrogen tellurite (K ₂ H ₄ TeO ₆ ), sodium tellurite (Na ₂ TeO ₃ ), and potassium tellurite (K ₂ TeO ₃ ).

2. The source of telluric acid ions in the telluric acid-containing rust preventive coating agent is telluric acid (H ₆ TeO
₆ ).

3. The source of the aqueous resin in the telluric acid-containing rust preventive coating agent is at least one of a polyolefin resin, a polyurethane resin, an acrylic resin, a polycarbonate resin, a polyester resin, an alkyd resin, a phenol resin, and a heat-curable resin. One kind.

4. The water-based resin may be mixed at an arbitrary ratio, or two or more resins may be mixed.

5. The rust-preventive coating agent contains 1 to 80 parts by weight of a water-based resin in solid content, 99 to 20 parts by weight of water, and 0.5 to 50 g / l of tellurate ion with respect to the coating agent.
1 is contained.

6. The rust-preventive coating agent contains 1 to 80 parts by weight of an aqueous resin as solid content, 99 to 20 parts by weight of water, and 2 to 20 g / l of tellurate ion based on the coating agent.

7. The rust-preventive coating agent has a pH of 3 to 1.
2 range.

8. The rust preventive additive is added to the rust preventive coating agent.

9. The rust preventive additive described in the above “8.”
It is at least one of phosphate ions and water-dispersible silica.

10. The content of phosphate ions with respect to the rust preventive coating agent is 0.1 to 5 g / l.

11. Examples of the water-dispersible silica include commercially available silica gel of "Snowtex N" (manufactured by Nissan Chemical Industries, Ltd.) and "Adelite AT-20N" (manufactured by Asahi Denka Kogyo KK), or commercially available Aerosil powder silica particles.

12. The content of the water-dispersible silica is 0.1 to 30 parts by weight based on 100 parts by weight of the aqueous resin solid content.
Parts by weight.

13. Rust-preventive coating agents are also pigments,
At least one of a surfactant and a silane coupling agent is blended.

14. Examples of the pigment described in the above “13.” include titanium oxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO), and calcium carbonate (CaCO ₂ ).
₃ ), barium sulfate (BaSO ₄ ), alumina (Al ₂
O _3), kaolin clay, carbon black, and organic pigments such as iron oxide _{(Fe 2 O 3, Fe 3} O 4), is at least one of various color pigments organic pigments.

15. Examples of the silane coupling agent described in the above “13.” include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Methacryloxypropyltriethoxysilane, N-
It is at least one kind of [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane.

16. The rust prevention treatment is a method of applying the above rust preventive coating agent to the object to be coated, heating the object to be coated with hot air after application, and drying the object, or heating the object to be coated in advance, and then heating the rust preventive coating agent when hot A method of applying and drying using residual heat is used.

17. The heating temperature described in the above “16.” is 50 to 250 ° C. in any of the above methods.

18. The coating thickness of the anti-rust coating agent is
The dry film thickness is 0.1 μm or more. 19. More preferably, the coating film thickness of the rust preventive coating agent is 0.1 to 20 μm in dry film thickness.

20. More preferably, the coating thickness of the rust preventive coating agent is 0.1 to 10 μm in dry film thickness.

[0055]

Next, the present invention will be described in detail with reference to examples and comparative examples. Note that the present invention is not limited by these examples.

Examples 1 to 7 and Comparative Examples 1 to 3 (1) Evaluation method: a) SST test (SST resistance);
Was sprayed on the coating surface of the object to be coated, and the degree of white rust after 48 hours 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 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 generation on the entire surface b) Warm water test (moisture resistance): After immersion in 40 ° C. constant temperature water for 20 days, the degree of white rust generation was evaluated out of 10 points. 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 on the whole surface (2) Rust prevention treatment condition; <Example 1> The polyolefin resin described in Note) was used so that the resin solid content concentration was 20% by weight. Was diluted with pure water, and tellurate ion was dissolved at 10 g / l, ammonium phosphate was further dissolved at 1.25 g / l, and "Snowtex N" (manufactured by Nissan Chemical Industries, Ltd.) was added at 25 g / l. 3
The mixture was stirred and dispersed for 0 minute, and adjusted to pH 8.0 to obtain a rust preventive coating agent. The obtained rust-preventive coating agent was previously heated to a sheet temperature of 80 ° C. (heating before painting). A commercially available hot-dip galvanized steel sheet (Z-27, manufactured by Nippon Test Panel, 70 × 150 × 1.6 mm). Was coated with a bar coat # 5 so as to have a dry film thickness of 2 to 3 μm and dried. Hot-dip galvanized steel sheet is polished with Scotch Bright and then degreased with alkali ("Surf Cleaner 5").
3 ", manufactured by Nippon Paint Co., Ltd.), and then the above evaluation was performed. Table 1 shows the evaluation results.

<Examples 2 and 3> The procedure was performed in the same manner as in Example 1 except that the addition concentration of tellurate ion was 0.5 g / l (Example 2) and 50 g / l (Example 3). . Table 1 shows the evaluation results. <Example 4> As an aqueous resin to be used, a polyolefin resin and a polyurethane resin described in Note) were used, and these resins were mixed so that the solid content ratio became 1: 1. Was adjusted to 20% by weight according to Example 1. Table 1 shows the evaluation results.

<Example 5> The procedure of Example 1 was repeated except that phosphate ion and "Snowtex N" were not added. Table 1 shows the evaluation results.

<Example 6> As the aqueous resin used,
Except that the polyolefin resin and the acrylic resin described in Note) were mixed together so that the solid content ratio of these resins was 1: 1 so that the total resin solid content concentration was 20% by weight. Was performed according to Example 1. Table 1 shows the evaluation results.

<Example 7> The procedure of Example 1 was repeated except that the epoxy resin described in Note) was used. Table 1 shows the evaluation results.

Comparative Example 1 The procedure of Example 1 was repeated, except that 5 g / l of chromate ion (strontium salt) was added instead of tellurate ion. Table 1 shows the evaluation results.

<Comparative Example 2> 0.3 g /
Except that l was added, it carried out according to Example 1. Table 1 shows the evaluation results.

Comparative Example 3 Tellurate ion was added at 60 g / l.
Except having added, it carried out according to Example 1. Table 1 shows the evaluation results.

[0064]

[Table 1] Note) Resin used Polyolefin resin: "HI-TECH S-7024"
(Toho 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.) "Snowtex N": water Dispersible silica (manufactured by Nissan Chemical Industries, Ltd.) From these results, according to the rust-preventive coating agent containing telluric acid of the present invention and the rust-preventive treatment method, the corrosion resistance and rust-prevention properties are significantly improved as compared with the conventional one. There was found.

[0065]

As described above, according to the rust preventive coating agent containing telluric acid according to the present invention and the rust preventive treatment method, the rust preventive properties can be greatly improved by adding telluric acid. That is, the tellurate ions not only passivate the base metal, but also remain in the resin film derived from the aqueous resin, and the tellurate ions promote the crosslinking reaction of the resin, thereby forming a dense rust-preventive film. be able to. Therefore, this rust-preventive film prevents moisture and harmful ions from permeating, and is therefore excellent in rust-preventive properties.

In addition, the rust-preventive metal material coated with the telluric acid-containing rust-preventive coating agent according to the present invention forms a film having excellent rust-preventive properties for the same reason as described above, so that generation of rust is suppressed. can do.

Claims (3)

[Claims] 1. A rust preventive coating agent characterized in that a composition mainly composed of an aqueous resin and water contains 0.5 to 50 g / l of tellurate ion. 2. A rust-preventive treatment method comprising coating a zinc-coated steel or an uncoated steel with the rust-preventive coating agent according to claim 1. 3. A rust preventive metal material coated with the rust preventive coating agent according to claim 1.