JP2002069660A - Aqueous agent for metal surface treatment without including hexa-valent chromium and metal sheet surface-treated therewith - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To not include hexavalent chromium and to have corrosion resistance on the surface of a metal material.
Provided are an aqueous metal surface treatment agent capable of forming a film having excellent conductivity and fingerprint resistance, and a surface-treated metal plate treated with the treatment agent. The metal (A) contains (A) a trivalent chromium compound, (B) a metal nitrate, (C) water-dispersible silica, and water, and the metal in the component (A) and the component (B). The weight ratio (A) / (B) to the metal in the range is 5/95 to 95/5 6
It is an aqueous metal surface treatment agent that does not contain valent chromium. The ratio of the solid content of the component (C) to the total solid content of the components (A), (B) and (C) is preferably from 10 to 90% by weight. Further, it is preferable to include, as additional components, an aqueous resin such as an acrylic resin, a urethane resin, and an epoxy resin, a phosphate compound, and a lubricant. The aqueous metal surface treating agent is applied to at least one surface of the metal surface and dried to form a film having a dry film weight of 0.1 to 5 g / m ² .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous metal surface treating agent which does not contain hexavalent chromium which is a substance harmful to the human body and which forms a coating layer having excellent corrosion resistance, conductivity and fingerprint resistance. The present invention relates to a surface-treated metal plate treated with a metal surface treating agent.

[0002]

2. Description of the Related Art Conventionally, a steel sheet for household appliances and a steel sheet for building materials have been subjected to a chromate treatment for the purpose of improving corrosion resistance on the surface of a galvanized steel sheet, but this chromate treatment is harmful to the environment and the human body. Contains hexavalent chromium. For this reason, in recent years, there has been an increasing demand for a chemical conversion treatment not containing hexavalent chromium and further a chemical conversion treatment not containing chromium itself. The required performance for these chemical conversion treatments is corrosion resistance, conductivity, fingerprint resistance,
Performance equivalent to conventional chemical conversion treatment such as paint adhesion is required.

[0003] As a prior art relating to such a chemical conversion treatment, Japanese Patent Application Laid-Open No. 2000-054157 and Japanese Patent Application Laid-Open
There is a method described in Japanese Patent Application Laid-Open No. 0-000519.
JP-A-2000-054157 discloses a chemical conversion surface treatment agent containing a metal such as phosphorus and molybdenum and trivalent chromium ions, and not containing hexavalent chromium and fluoride. When this treatment agent is used, the temporary rust prevention level of the chromate treatment which is a conventional chemical conversion treatment (Cr adhesion amount 10 m
g / m ² , the amount of white rust generated area is less than 10% after 72 hours of salt spraying), the amount of the film must be 1 g / m ² or more, and the fingerprint resistance of the obtained film is also high. There is a problem that it is hard to say enough.

Japanese Patent Application Laid-Open No. 2000-000519 discloses that the surface of a zinc-based or aluminum-based plated steel sheet is
A surface-treated steel sheet formed by forming a protective film containing a water-dispersible resin and / or a water-soluble resin and a polymer chelating agent having a chelating group in a polymer matrix as a main component and a surface treatment method thereof are disclosed. ing. In this method, since a water-dispersible resin and / or a water-soluble resin are the main components, fingerprint resistance is good, but there is a problem that conductivity is poor. Thus, corrosion resistance without any hexavalent chromium,
At present, a surface-treated metal plate having a film excellent in both conductivity and fingerprint resistance has not been obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and does not contain hexavalent chromium. An object of the present invention is to provide an aqueous metal surface treatment agent capable of forming a film having excellent fingerprint properties.
It is another object of the present invention to provide a surface-treated metal sheet treated with the aqueous metal surface treating agent.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on means for solving the problems of the prior art, and as a result, they have found that they contain a trivalent chromium compound, a metal nitrate, and water-dispersible silica. It has been found that the above problems can be solved by using a water-based metal surface treatment agent, and the present invention has been achieved.

That is, the present invention provides (A) a trivalent chromium compound, (B) a metal nitrate, (C) water-dispersible silica, and water, and Weight ratio of (A) / (B) to the metal in component (B) is 5 / 95-
It is a water-based metal surface treatment agent containing no hexavalent chromium, characterized in that it is in the range of 95/5.

In the above aqueous metal surface treating agent, the metal in the metal nitrate salt of the component (B) is an alkaline earth metal, C
It is preferably at least one metal selected from the group consisting of o, Ni, Fe, Zr and Ti. The ratio of the solid content of the component (C) to the total solid content of the components (A), (B) and (C) is preferably from 10 to 90% by weight. The aqueous metal surface treating agent preferably contains (D) an aqueous resin as an additional component. The water-based resin is preferably at least one water-based resin selected from the group consisting of an acrylic resin, a urethane resin, and an epoxy resin. Further, it is preferable to include (E) a phosphate compound as the additional component (E). Also, as an additional component,
(F) It is preferable to include a lubricant.

Further, the present invention provides a surface treatment comprising applying the above aqueous metal surface treating agent to at least one surface of a metal surface and drying to form a film having a dry film weight of 0.1 to 5 g / m ^2. It is a metal plate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail. The aqueous metal surface treating agent of the present invention contains component (A) a trivalent chromium compound and does not contain a hexavalent chromium compound. Although the compound of trivalent chromium is not particularly limited, chromium (III) sulfate, chromium (III) nitrate, chromium (III) biphosphate, chromium (III) fluoride, chromium (III) halide, and the like can be used. No. Further, one obtained by reducing all hexavalent chromium to trivalent chromium may be used. The amount of component (A) to be incorporated into the aqueous metal surface treating agent of the present invention is not particularly limited.

The metal of the metal nitrate salt of the component (B) used in the present invention is not particularly limited, but alkaline earth metals such as Mg, Ca and Ba, Co, Ni, Fe, Zr and Ti
Preferably, a metal is used for at least one selected from the group consisting of The blending amount of the component (B) in the aqueous metal surface treating agent of the present invention is not particularly limited.

As described above, the amounts of component (A) and component (B) in the aqueous metal surface treating agent of the present invention are not particularly limited, but the metal in component (A) and the metal in component (B) are mixed. Weight ratio (A) / (B) needs to be in the range of 5/95 to 95/5. The ratio of (A) / (B) is preferably 10/90 to 90/10, more preferably 15/90.
It is in the range of 85 to 85/15. If the ratio of (A) / (B) is less than 5/95 or exceeds 95/5, the level of corrosion resistance is insufficient, which is not preferable.

The water-dispersible silica of the component (C) used in the present invention includes colloidal silica and gas-phase silica.
Examples of the colloidal silica include, but are not limited to, Snowtex C, Snowtex O, Snowtex N, Snowtex S, Snowtex UP, Snowtex PS-M, Snowtex PS-L, Snowtex 20, Snowtex Tex 30, Snowtex 4
0 (trade names, both manufactured by Nissan Chemical Industries, Ltd.). Examples of the gas phase silica include, but are not particularly limited to, Aerosil 50, Aerosil 130, Aerosil 200, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil MOX80, Aerosil MOX170 (trade name, all manufactured by Nippon Aerosil Co., Ltd.), and the like. Is mentioned.

In the aqueous metal surface treating agent of the present invention,
The ratio of the solid content of the component (C) to the total solid content of the components (A), (B) and (C), that is, the component (C) based on 100% by weight of the total solid content of the components (A) to (C) Is preferably 10 to 90% by weight. More preferably, it is 20 to 80% by weight. If this ratio is less than 10% by weight, the resulting film is inferior in corrosion resistance and fingerprint resistance, which is not preferable. On the other hand, if this proportion exceeds 90% by weight, the absolute amounts of the components (A) and (B) which are effective for corrosion resistance are reduced, and the corrosion resistance is undesirably reduced.

The aqueous metal surface treating agent of the present invention may further contain (D) a water-soluble and / or water-dispersible resin, so-called aqueous resin, as an additional component for the purpose of further improving corrosion resistance. Examples of the aqueous resin include an acrylic resin, a urethane resin, an epoxy resin, a polyester resin, a phenol resin, a vinyl acetate resin, a vinylidene chloride resin, and at least one selected from the group consisting of an acrylic resin, a urethane resin, and an epoxy resin. Some aqueous resins are preferred.

The aqueous acrylic resin is not particularly limited, but includes acrylic monomers such as (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylic acid amide, and vinyl copolymerizable therewith. Copolymers with compounds (eg, styrene, acrylonitrile, etc.) are preferred, and those using a reactive emulsifier during polymerization are more preferred. For example, Primal K-3 (trade name, manufactured by Rohm & Haas) and the like can be mentioned.

The aqueous urethane resin is not particularly limited, but it is preferable to use a self-emulsifying type (a type which disperses in water without using an emulsifier). Examples of such a resin include Superflex 110,
Super Flex 150, Super Flex 30
0, Superflex 420 (trade name, both manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekabon Titer HUX-2
32, Adekabon titer HUX-240, Adekabon titer HUX-380 (trade name, all manufactured by Asahi Denka Kogyo KK) and the like.

The aqueous epoxy resin is not particularly limited, but it is preferable to use an aminated modified product such as a bisphenol type epoxy resin, a phenol novolak type epoxy resin, and an orthocresol novolak type epoxy resin. For example, Adeka Resin EPE-0436
B (trade names, all manufactured by Asahi Denka Kogyo KK) and the like.

The ratio of the solid content of the component (D) to 100% by weight of the total solid content of the components (A) to (D) is preferably 1%.
It is 0 to 90% by weight, more preferably 20 to 85% by weight. If this ratio is less than 10%, the effect of improving the corrosion resistance is poor, while if it exceeds 90%, the absolute amounts of the components (A) to (C) which are effective in the corrosion resistance are undesirably small.

By adding a phosphoric acid compound (E) as an additional component, it is possible to further improve the corrosion resistance.
The phosphoric acid compound is not particularly limited. For example, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, phosphoric acid 2 Potassium hydrogen, 2 potassium hydrogen phosphate, 3 potassium phosphate,
Magnesium hydrogen phosphate, magnesium phosphate, calcium hydrogen phosphate, calcium phosphate, ammonium tripolyphosphate, sodium tripolyphosphate, potassium tripolyphosphate, magnesium tripolyphosphate, calcium tripolyphosphate, ammonium pyrophosphate, sodium pyrophosphate, potassium pyrophosphate, magnesium pyrophosphate And calcium pyrophosphate.

The ratio of the solid content of the component (E) to 100% by weight of the total solid content of the components (A) to (E) is 0.1 to 10%.
% By weight, more preferably 0.2 to 5% by weight. When the ratio of the solid content of the component (E) to the total solid content of the components (A) to (E) is less than 0.1% by weight, the effect of improving the corrosion resistance is poor, while the content exceeds 10% by weight. In this case, the effect of improving the corrosion resistance is saturated, so that it is not economical.

By adding a lubricant (F) as an additional component, it is possible to further improve the corrosion resistance, and it is expected that workability can be improved by adding the lubricant. Although there is no particular limitation on the lubricant, polyethylene wax,
Examples include aqueous dispersions of polypropylene wax, paraffin wax, microcrystalline wax, carnauba wax, polytetrafluoroethylene and the like. The method for dispersing these lubricants in water is not particularly limited, but a method in which the lubricant is dispersed in water using a surfactant, an oxidized wax, or the like is preferable. For example, Chemipearl W900 and Chemipearl WP250 (trade names, both manufactured by Mitsui Chemicals, Inc.).

The ratio of the solid content of the component (F) to the total solid content of the components (A) to (F) is preferably 1 to 20% by weight, more preferably 2 to 15% by weight.
When the ratio of the solid content of the component (F) to the total solid content of the components (A) to (F) is less than 1% by weight, the effect of improving the corrosion resistance is poor. On the other hand, when the ratio exceeds 20% by weight, It is not economical because the effect of improving corrosion resistance is saturated.

Next, the surface-treated metal plate of the present invention will be described. The surface-treated metal sheet of the present invention is obtained by applying the above-mentioned aqueous metal surface treating agent of the present invention to at least one surface of a metal material and drying the same.
The film of No. ² was formed. The dry film weight is 0.
If it is less than 1 g / m ² , the corrosion resistance is insufficient, which is not preferable. On the other hand, when the dry film weight exceeds 5 g / m ² , the effect of improving the corrosion resistance is saturated, which is not economical.

The metal sheet in the surface-treated metal sheet of the present invention may be a galvanized steel sheet (for example, an electrogalvanized steel sheet, a hot-dip galvanized steel sheet, an alloyed hot-dip galvanized steel sheet), a galvanized steel sheet containing aluminum (5% Aluminum-containing hot-dip galvanized steel sheet, 55% aluminum-containing hot-dip galvanized steel sheet, etc.), aluminum-plated steel sheet,
A zinc-nickel alloy-plated steel sheet is exemplified. After the surfaces of these metal materials are cleaned by alkali degreasing, pickling, or the like, it is preferable to apply and dry the aqueous metal surface treating agent of the present invention.

As a method of applying the aqueous metal surface treating agent,
Although not particularly limited, a roll coater method, a dipping method, an electrostatic coating method, or the like can be used. Drying after coating is preferably performed at a temperature of the ultimate plate at 60 to 200 ° C.

In addition, a resin film can be applied on a surface-treated metal plate treated with the aqueous metal surface treating agent of the present invention for the purpose of further improving corrosion resistance.
The resin film at this time is not particularly limited, but is preferably formed by applying a surface treatment agent mainly composed of an acrylic resin, a urethane resin, an epoxy resin, a polyester resin, and the like. The weight is preferably in the range of 0.5 to 10 g / m ^{2 on} a dry weight basis.

[0028]

The present invention will be specifically described below with reference to examples and comparative examples. It should be noted that these examples are described for describing the present invention, and do not limit the present invention in any way.

[Preparation of Test Material] (1) Test Material The following commercially available materials were used as test materials.・ Electro-galvanized steel sheet (EG) 0.8 mm thick, plating weight 20/20 (g / m ² ) ・ Galvanized steel sheet (GI) 0.8 mm thick, plating weight 60/60 (g / m) ² ) ・ 5% aluminum-containing galvanized steel sheet (GF) 0.8 mm thick, plating weight 90/90 (g / m ² ) ・ 55% aluminum-containing galvanized steel sheet (GL) 0.8 mm thick, plating 90/90 (g / m ² )

(2) Degreasing treatment Each of the above test materials was degreased (concentration: 20 g / L, temperature: 60) with a fine silicate alkaline degreasing agent, Fine Cleaner 4336 (registered trademark: manufactured by Nippon Parkerizing Co., Ltd.).
(Sprayed at 20 ° C. for 20 seconds) and then washed with tap water.

[Preparation of Aqueous Metal Surface Treatment Agent] The trivalent chromium compounds used in the preparation of the aqueous metal surface treatment agents of Examples and Comparative Examples are shown in Table 1, metal nitrate salts are shown in Table 2, and water-dispersible silica is shown in Table 1. In Table 3, the aqueous resin is shown in Table 4, and the phosphate compound is shown in Table 5.
And lubricants are shown in Table 6.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

[Table 6]

At room temperature, the trivalent chromium compounds of Table 1
Metal nitrate, water-dispersible silica in Table 3, water-based resin in Table 4, phosphate compound in Table 5, and lubricant in Table 6 were distilled in this order at the composition ratios shown in Tables 7 and 8. Put in water,
The aqueous metal surface treating agent was prepared by mixing with stirring using a propeller stirrer. Table 7 shows the compositions of the prepared aqueous metal surface treating agents of the examples. Table 8 shows the composition of the aqueous metal surface treating agent of the comparative example. The solid content of each of the aqueous metal surface treatment agents shown in Tables 7 and 8 was 10% by weight.
It is.

[0039]

[Table 7]

[0040]

[Table 8]

[Surface treatment with aqueous metal surface treating agent: preparation of surface treated metal plate] Each aqueous metal surface treating agent prepared above was applied to each of the degreased test plates with a bar coater. At 240 ° C. to produce a surface-treated metal plate. The coating amount (g / m ² ) was adjusted by appropriately adjusting the solid concentration of the aqueous metal surface treating agent. Each obtained surface-treated metal plate was subjected to a performance test as a test plate.

[Performance Test of Surface Treated Metal Sheet] (1) Plane Corrosion Resistance A salt spray test according to JIS-Z-2371 was performed for 72 hours for EG and GI materials, and 144 hours for GF and GL materials. The rust generation was observed, and the evaluation was performed according to the following criteria. <Evaluation Criteria> 白: White rust occurrence area ratio is less than 3% of the entire area ○: White rust occurrence area rate is 3% or more and less than 10% of the entire area △: White rust occurrence area rate is 10% or more of the entire area and 30 %: White rust generation area ratio is 30% or more of the entire area

(2) Conductivity Loresta MP MCP-T35 conductivity meter manufactured by Mitsubishi Chemical Corporation
The resistance was measured at 0 and evaluated according to the following criteria. <Evaluation Criteria> ◎: less than the resistance value is 10 ~ ³ Ω ○: resistance value of 10 to ³ or more 10 to less than ^{1 Ω} △: resistance value of 10 to ¹ or more 10 ¹ Ω less than ×: resistance value of 10 ^one or more

(3) Fingerprint Resistance The color tone (L value, a value, b value) of the test plate was measured with a color difference meter (ZE-2000, manufactured by Nippon Denshoku Co., Ltd.). Next, petrolatum was applied to this test plate and then wiped off, and the color tone after wiping was measured with a color difference meter. This difference in measured color tone (△ E)
Were evaluated based on the following criteria. ΔE = ((L ₂ −L ₁ ) ² + (a ₂ −a ₁ ) ² + (b ₂ −b ₁ )
^{2) 0} - ⁵ _{wherein, L 1, a 1, b} 1 before petrolatum coating, L _2, a _2,
b ₂ denotes the value after petrolatum coating. <Evaluation Criteria> △: ΔE is less than 2 ○: ΔE is 2 or more and less than 3 Δ: ΔE is 3 or more and less than 5 ×: ΔE is 5 or more

[Results of Performance Test] Table 9 shows the test results of the surface-treated metal plate of the example of the present invention, and Table 10 shows the test results of the surface-treated metal plate of the comparative example.

[0046]

[Table 9]

[0047]

[Table 10]

The surface-treated metal plates of Examples 1 to 23 obtained by treating with the aqueous metal surface treating agents of Examples 1 to 19 of the present invention have all of the flat part corrosion resistance, conductivity and fingerprint resistance. It was good. On the other hand, the surface-treated metal plate of Comparative Example 1 obtained by treating with the aqueous metal surface treating agent of Comparative Example 20 of the aqueous metal surface treating agent showed good results, but this was harmful to the human body and the environment. It differs from the purpose of the present invention because it contains hexavalent chromium. And the comparative examples 21-24 which are out of the range of the present invention.
Comparative Examples 2 to 2 obtained by treating with an aqueous metal surface treating agent
In the surface-treated metal plate of No. 5, the conductivity and the fingerprint resistance were relatively good, but the most important performance, that is, the flat part corrosion resistance, was inferior.

[0049]

As described above, the film formed by applying and drying the aqueous metal surface treating agent of the present invention on the surface of a metal material is excellent in corrosion resistance, conductivity, and fingerprint resistance, and is excellent in human body. Since it does not contain hexavalent chromium which is harmful to the environment, its industrial utility value is very large.

Continued on the front page F term (reference) 4K026 AA02 AA07 AA09 AA12 AA13 AA22 BA01 BB04 BB08 BB10 CA16 CA19 CA23 CA24 CA32 CA39 CA41 DA15 DA16

Claims (8)

[Claims] 1. A composition comprising (A) a trivalent chromium compound, (B) a metal nitrate, (C) water-dispersible silica, and water, and the metal in the component (A) and the component (B) An aqueous metal surface treatment agent containing no hexavalent chromium, wherein the weight ratio (A) / (B) to the metal in the mixture is in the range of 5/95 to 95/5. 2. The metal in the metal nitrate salt of the component (B) is at least one metal selected from the group consisting of alkaline earth metals, Co, Ni, Fe, Zr and Ti.
The aqueous metal surface treating agent as described in the above. 3. The ratio of the solid content of the component (C) to the total solid content of the components (A), (B) and (C) is 10%.
The water-based metal surface treating agent according to claim 1 or 2, wherein the amount is from 90 to 90% by weight. 4. The aqueous metal surface treating agent according to claim 1, further comprising (D) an aqueous resin as an additional component. 5. The method according to claim 1, wherein the aqueous resin is at least one selected from the group consisting of an acrylic resin, a urethane resin and an epoxy resin.
The aqueous metal surface treating agent according to claim 4, which is a kind of aqueous resin. 6. The aqueous surface treating agent according to claim 1, further comprising (E) a phosphate compound as an additional component. 7. The aqueous surface treating agent according to claim 1, further comprising (F) a lubricant as an additional component. 8. An aqueous metal surface treating agent according to any one of claims 1 to 7, which is applied to at least one surface of the metal surface and dried to form a film having a dry film weight of 0.1 to 5 g / m ² . Surface treated metal plate formed.