JP2005194627A - Water based treatment chemical for metal surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart heat resistance, electrical conductivity and fingerprint resistance to a blackening-treated Zn-Ni based alloy plated steel sheet in addition to fine black appearance and satisfactory corrosion resistance by applying non-chromium type water based surface treatment thereto. <P>SOLUTION: A blackening-treated steel sheet is coated with a water based treatment chemical with a pH of 7 to 10 comprising: (A) a water soluble or water dispersible polyolefin based resin (preferably, a copolymer resin in which the monomer ratio of ethylene/acrylic acid is, by mass, 85/15 to 75/25) in 50 to 80 mass%; (B) at least one kind of water soluble metallic compound containing metal selected from zirconium, vanadium and titanium in 5 to 15 mass%; (C) colloidal silica in 10 to 30 mass%; (D); an organic compound capable of forming chelate in 0.5 to 5 mass%: (E) at least one kind of compound selected from inorganic acids and the salts thereof in 0.5 to 10 mass%; and (F) non-volatile components composed of a silane coupling agent in 0 to 10 mass%, and comprising no chromium, and drying is performed to form a film in which dry weight is 0.1 to 3 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a chromium-free aqueous treatment agent for imparting corrosion resistance to a metal surface, particularly a Zn-Ni alloy-plated steel plate or a blackened zinc-based alloy-plated steel plate, particularly a blackened Zn- The present invention relates to an aqueous treatment chemical suitable for surface treatment of Ni-based alloy plated steel sheets. When surface treatment is performed on zinc-plated steel sheets, especially Zn-Ni alloy-plated steel sheets, that have been blackened using this water-based treatment agent, in addition to good black appearance and corrosion resistance, heat resistance, conductivity, and fingerprint resistance A surface-treated steel sheet having high properties can be obtained. The present invention also relates to such a surface-treated steel sheet.

  Blackened steel sheets are widely used mainly for home appliances such as personal computers, copiers, AV equipment, and air conditioners. A blackened steel sheet can be manufactured by applying a black paint to the steel sheet surface, but after the zinc-nickel (Zn-Ni) alloy-plated steel sheet is blackened by anodic electrolytic oxidation or the like, chromate or Products manufactured by applying an organic resin are becoming mainstream because they are superior in terms of performance such as cost, corrosion resistance, black appearance and durability.

  Conventional blackened steel sheets manufactured by blackening treatment are generally subjected to chromate treatment to form a chromate film on the surface in order to improve corrosion resistance. However, since the chromate film contains harmful chromium compounds, it may cause environmental pollution and affect the health of humans involved in the treatment. Therefore, surface treatment that does not use chromium compounds is desired. Yes.

  In recent years, a technology has also been developed in which a Zn-Ni alloy-plated steel sheet is blackened without forming a harmful chromate film, and then directly coated with an organic resin and dried to obtain a blackened steel sheet. Yes.

  In JP 2000-290783, a zinc / plated steel sheet is used as a base, and a nickel / zinc metal, nickel / zinc oxide, and optionally a hydroxide on the surface of the zinc plated steel sheet. Forming an oxide composite blackening film, and further comprising a resin and at least one of a thiocarbonyl group-containing compound and a vanadate compound, optionally including at least one of a phosphate compound and fine silica, A technology for a non-chromium-type black-treated zinc-plated steel sheet is disclosed, in which a non-chromium-type rust-proof coating layer is formed and, if necessary, an upper layer further has an organic resin layer optionally containing a black pigment and / or a rust-preventive pigment. ing.

  In JP 2001-158969 A and JP 2001-164377 A, when applied to a blackened steel sheet, it has excellent corrosion resistance and does not cause color change such as yellowing, greening, whitening, or low gloss. A water-soluble or water-dispersible organic resin composition containing a metal ion or an acid component and a black steel sheet coated with the same are disclosed.

  Japanese Patent Laid-Open No. 2002-127302 discloses a water-dispersible organic resin having a metal ion, an acid, a glass transition temperature under specific conditions, a solubility parameter, and a refractive index on the surface of a blackened Zn-Ni alloy-plated steel sheet. The technique of the black steel plate which apply | coated the composition containing this is disclosed.

Various applications such as corrosion resistance, heat resistance, electrical conductivity, fingerprint resistance, etc. are required for household appliances as well as beautiful black appearance. , They could not satisfy all of their performance in a well-balanced manner.
JP 2000-290783 A JP 2001-158969 A JP 2001-164377 A JP 2002-127302 A

  The present invention provides not only a beautiful black appearance and good corrosion resistance, but also heat resistance, conductivity and fingerprint resistance when used for surface treatment of blackened zinc-based plated steel sheets, particularly Zn-Ni alloy-plated steel sheets. It is an object of the present invention to provide a water-based treatment chemical that does not contain chromium harmful to the environment and a surface-treated steel plate produced by using this treatment chemical, which can produce a non-chromium-type blackened steel plate having both properties.

  According to the present invention, the above object is achieved by an aqueous treatment agent having a non-volatile component comprising a specific organic resin, metal compound, colloidal silica, organic compound, inorganic acid or salt thereof, and more preferably a silane coupling agent. Can do.

  That is, the present invention relates to (A) a water-soluble or water-dispersible polyolefin resin 50 to 80% by mass, (B) at least one water-soluble metal compound 5 to 15 containing a metal selected from zirconium, vanadium and titanium. Mass%, (C) colloidal silica 10-30 mass%, (D) chelate-forming organic compound 0.5-5 mass%, (E) at least one compound selected from inorganic acids and water-soluble salts thereof 0.5- 10% by mass and (F) a water-based treatment agent for metal surfaces having a non-volatile component consisting of 0 to 10% of a silane coupling agent and not containing chromium.

  The water-soluble or water-dispersible polyolefin-based resin is preferably an ethylene-acrylic acid copolymer resin, and more preferably an ethylene-acrylic resin having a mass ratio of ethylene / acrylic acid of 85/15 to 75/25. It is an acid copolymer resin. The pH of the aqueous treatment chemical of the present invention is preferably 7-10.

The present invention also provides a surface-treated steel sheet characterized by having a film formed by applying and drying the aqueous treatment chemical on the plated surface of a zinc-nickel alloy-plated steel sheet. Furthermore, the coating surface of the zinc-based alloy plated steel sheet that has been blackened, preferably the zinc-nickel alloy-plated steel sheet that has been blackened, has a film formed by applying and drying the aqueous processing agent. A featured surface treated steel sheet is also provided. The dry film weight of the formed film is preferably in the range of 0.1 to 3 g / m ² .

  Black-plated zinc-based plated steel sheet, especially Zn-Ni alloy-plated steel sheet, and an aqueous treatment agent having a predetermined composition not containing chromium of the present invention (aqueous organic resin, metal compound, colloidal silica, organic compound) , Inorganic acid or salt thereof, and optionally containing a silane coupling agent) and drying to form a film, not only beautiful appearance and good corrosion resistance, but also heat resistance, conductivity, fingerprint resistance A non-chromium-type black-treated galvanized steel sheet having both properties can be obtained.

  In addition, even if the Zn-Ni alloy-plated steel sheet is not blackened, the appearance does not become black, but in addition to very good corrosion resistance, it also has heat resistance, conductivity, and fingerprint resistance, and is non-chromium A surface-treated zinc-based plated steel sheet of the mold is obtained.

Water treatment chemicals:
The components (A) to (F) of the aqueous treatment chemical according to the present invention will be described. The content (%) of each component contained in the aqueous treatment chemical of the present invention is mass% with respect to the total amount of the non-volatile components, and therefore is substantially equal to the content in the dry film formed from this treatment chemical. Correspondingly.

(A) Organic resin 50-80% of a water-soluble or water-dispersible polyolefin resin is contained as a main film-forming component of the aqueous treatment chemical of the present invention. The polyolefin resin is not particularly limited as long as it is water-soluble or water-dispersible. A preferred example of such a resin is an ethylene-acrylic acid copolymer resin. Examples of other polyolefin resins that can be used in the present invention include ethylene-methacrylic acid copolymer resins, ethylene-maleic acid copolymer resins, ethylene-ethyl acrylate copolymer resins, ethylene-vinyl sulfonic acid copolymer resins, propylene. -Maleic acid copolymer resin etc. are mentioned.

  As a result of examining various systems as organic resins, water-soluble or water-dispersible polyolefin-based resins are required to maintain a beautiful black appearance and to have good corrosion resistance and heat resistance (less color change after heating). It has been found effective to contain 50-80% of a resin, particularly an ethylene-acrylic acid copolymer resin. When the amount of the polyolefin resin is less than 50%, the barrier property of the film cannot be obtained, and the corrosion resistance and the surface appearance are deteriorated. On the other hand, when the amount exceeds 80%, the resin component is too much and the heat resistance is lowered. The content of the polyolefin resin (A) is preferably 55 to 70%.

  Here, the deterioration of the surface appearance refers to a phenomenon in which the coating becomes whitish and cloudy and looks like coating unevenness, and greatly impairs the commercial value for a black steel sheet that requires a beautiful appearance.

  The ethylene-acrylic acid copolymer resin used as the polyolefin resin (A) preferably has an ethylene / acrylic acid monomer ratio in the range of 85/15 to 75/25 by mass ratio. When the ratio of acrylic acid in the monomer ratio of ethylene / acrylic acid is less than 15% by mass, the adhesion of the formed film to the steel sheet surface may be lowered, and the corrosion resistance may be lowered. On the other hand, when the proportion of acrylic acid exceeds 25% by mass, the hydrophilicity of the formed film increases and the corrosion resistance may decrease.

  As is well known to those skilled in the art of acrylic resins, in the ethylene-acrylic acid copolymer resin used in the present invention, part or all of acrylic acid is converted to substituted acrylic acid such as methacrylic acid or ethacrylic acid. Can be changed. In addition, it is possible to copolymerize small amounts of other ethylenically unsaturated monomers. 1 type (s) or 2 or more types can be used for ethylene-acrylic acid copolymer resin.

(B) Metal compound Corrosion resistance is drastically improved by containing one or two or more metal compounds containing a metal selected from zirconium, vanadium and titanium in an amount of 5 to 15%. . If the content of this metal compound (total amount when containing two or more) is less than 5%, the effect of improving corrosion resistance will be insufficient, and if it exceeds 15%, the liquid stability of the drug will be reduced. Costs also rise. A preferable content of the metal compound (B) is 8 to 15%.

A metal compound containing zirconium, vanadium or titanium is a water-soluble compound (in addition to the case where the compound itself is water-soluble, a compound which dissolves in combination with a chelate-forming organic compound described below is also a water-soluble metal in the present invention. It is not particularly limited as long as it is included in the compound. For example, it may be in the form of inorganic acid salts such as sulfates, nitrates, phosphates and carbonates, organic acid salts such as acetates and oxalates, double salts and complex salts, and oxides. . Further, it may be in the form of a metal acid such as vanadic acid, vanadyl compound (VO ²⁺ ), titanic acid or zirconic acid, or a salt thereof.

Specific examples of such metal compounds include, for example, zirconyl sulfate [ZrOSO ₄ ], zirconyl nitrate [ZrO (NO ₃ ) ₂ ], zirconium acetate, zirconium propionate, zirconium lactate, hexafluorozirconium hydrogen acid, ammonium hexafluorozirconate , Potassium hexafluorozirconate, ammonium zirconium carbonate, zirconium acetyl acetate, vanadium pentoxide, metavanadate, ammonium metavanadate, sodium metavanadate, vanadium trichloride, vanadium trioxide, vanadium dioxide, vanadium oxysulfate, vanadium oxyacetylacetate Nato, vanadium acetylacetonate, vanadium trichloride, phosphovanadomolybdic acid, vanadium sulfate, vanadium dichloride, vanadium oxide, titanyl sulfate Titanium oxysulfate, hexafluorotitanate hydrogen, ammonium hexafluorotitanate, potassium titanium oxalate, titanium citrate, titanium lactate and the like.

(C) Colloidal silica By containing colloidal silica in an amount of 10 to 30%, the corrosion resistance and heat resistance of the coating are improved. If the colloidal silica content is less than 10%, the effect of improving corrosion resistance and heat resistance cannot be obtained sufficiently. When the content of colloidal silica exceeds 30%, the film becomes brittle and performances such as corrosion resistance and workability deteriorate. The content of colloidal silica is preferably 15 to 25%.

  The type and particle size of colloidal silica are not particularly limited. The colloidal silica may be a pure silicic acid colloid, may have been subjected to various stabilization treatments, or may have a surface coated.

(D) Chelate-forming organic compound Chelate-forming organic compound (organic compound capable of forming a chelate by coordinating with a metal) By containing an organic compound in an amount of 0.5 to 5%, a chemical solution for a treatment agent Stability (hereinafter referred to as chemical stability) and corrosion resistance of the film are improved. If the amount of the chelate-forming organic compound is less than 0.5%, the chemical solution stability decreases, and if it exceeds 5%, the chemical solution stability and the film corrosion resistance decrease.

  The chelate-forming organic compound is not particularly limited, but examples include dicarbonyl compounds such as acetylacetone, ethyl acetoacetate, dipivaloylmethane, and 3-methylpentanedione; tartaric acid, ascorbic acid, gluconic acid, citric acid, apple Oxycarboxylic acids such as acids; organic amines such as triethanolamine, ethylenediamine, imidazole, morpholine, and piperazine; acid amides such as formamide, acetamidepropionamide, and N-methylpropionamide; glycine, alanine, proline, glutamic acid, etc. Amino acids; phosphorus-containing organic compounds such as aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), pyrophosphate, phytic acid; glucose, Monosaccharides such as north and galactose; oligosaccharides of maltose and sucrose; natural polysaccharides such as starch and cellulose; aromatic compounds such as tannic acid, humic acid, lignin sulfonic acid and polyphenol; polyvinyl alcohol, polyethylene glycol and polyacryl Examples include synthetic polymers such as acid, polyacrylamide, polyethyleneimine, and aqueous nylon. Among these chelate-forming organic compounds, organic compounds containing at least two functional groups selected from a hydroxyl group, a carbonyl group, a carboxyl group, a phosphoric acid group, and a phosphonic acid group in one molecule are more preferable. .

(E) Inorganic acid or salt thereof When the treatment chemical contains at least one compound selected from inorganic acid and water-soluble salt in an amount of 0.5 to 10%, the outermost surface of the blackened steel sheet is activated. As a result, the reaction between the steel plate and the treatment chemical solution is promoted, and the corrosion resistance is improved. If the amount of the compound selected from inorganic acids and their salts (the total amount in the case of two or more) is less than 0.5%, these effects will be insufficient, and if it exceeds 10%, the corrosion resistance and chemical stability will decrease. . The preferred content of this compound is 1-7%.

  Compounds selected from inorganic acids and water-soluble salts thereof are not particularly limited, but examples include inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, and ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium nitrate, ammonium fluoride. Ammonium sulfate, potassium phosphate, potassium dihydrogen phosphate, potassium nitrate, potassium fluoride, sodium hydrogen phosphate, disodium hydrogen phosphate, sodium nitrate, sodium hydrogen sulfate, ammonium salts, potassium salts, sodium salts, etc. .

(F) Silane Coupling Agent The water-based treatment agent according to the present invention has good performance only with the above components (A) to (E), but further contains the silane coupling agent (F) in an amount of 10% by weight or less. When contained, the heat resistance and alkali resistance are further improved. This contributes to improved interlayer adhesion between the resin and the metal surface due to chemical bonding (crosslinking) that occurs between the resin and colloidal silica. When a silane coupling agent is added, the addition amount is preferably 1% or more. When the addition amount is less than 1%, the above-described improvements in both performances cannot be sufficiently obtained. When the added amount exceeds 10%, the improvement effect of both performances is saturated.

  The type of silane coupling agent to be blended is not particularly limited, but vinyltrichlorosilane, vinyltris (β-methoxyethoxysilane), vinyltriethoxysilane, vinyltrimethoxysilane, γ- (methacryloyloxypropyl) trimethoxysilane, β -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glyoxydoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxy Silane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloro Propyltrimethoxysilane Ureidopropyltriethoxysilane and the like.

For any of the above components (A) to (F), one or more components can be used. When using 2 or more types, a total amount should just be in the said range.
The aqueous treatment agent of the present invention preferably has a pH of 7-10. When the pH is lower than 7, the chemical solution stability decreases, and when the pH exceeds 10, the corrosion resistance of the film decreases. A more preferred pH is 8-9.

  If necessary, a basic compound is added to the aqueous treatment agent of the present invention to adjust the pH to be within the above range. As such a pH adjuster, those that do not affect the treatment film and have volatility are preferable. Examples include inorganic bases such as sodium hydroxide, calcium hydroxide, aqueous ammonia, and organic amines such as methylamine, dimethylamine, triethylamine, and ethylenediamine. Of these, ammonia water, methylamine, dimethylamine, and triethylamine are preferable.

Plated steel sheet:
Since the aqueous treatment chemical of the present invention is excellent in fingerprint resistance, it is particularly suitable for use in the surface treatment of a blackened steel sheet that is prominent in fingerprints. The blackening-treated plated steel sheet that serves as the substrate for the surface treatment is preferably a zinc-based alloy-plated steel sheet produced by electroplating, particularly a Zn-Ni-based alloy-plated steel sheet. For example, a Zn—Ni alloy-plated steel sheet having an adhesion amount of 5 to 40 g / m ² and an Ni content of 5 to 30% can be used. The type of the base steel plate is not particularly limited, and may be a high strength steel plate having a tensile strength of 340 MPa or more, as well as SPCC, SPDE, SPCE general and deep drawing steel plates.

  There is no particular limitation on the method of blackening treatment, and it may be blackened by any method such as an anodic electrolytic oxidation method, a method of immersing in an oxidizing liquid, or an alternating electrolysis method, but it is the most beautiful. A method by anodic electrolytic oxidation, which is a uniform blackening treatment method, is preferred. What carried out the immersion process in acid or alkali aqueous solution after blackening process may be used.

  In addition, the aqueous processing chemical | medical agent of this invention can also be applied to the normal galvanized steel plate which is not blackened. In a normal zinc-based plated steel sheet, a high-level surface appearance is not usually required for use, and since it is not blackened, the deterioration of the surface appearance itself is not noticeable. However, since corrosion resistance, weldability, and the like are performances that are also required for ordinary galvanized steel sheets, the aqueous treatment chemical of the present invention can be applied to improve these performances. Furthermore, the water-based treatment agent of the present invention can also be applied to metal surfaces other than galvanized steel sheets. As a zinc-based plated steel sheet that has not been blackened, it is particularly preferable to use a Zn-Ni alloy-plated steel sheet having good corrosion resistance.

Surface-treated steel sheet:
The surface-treated steel sheet of the present invention has a coating formed on the surface by applying the above-mentioned aqueous treatment chemical to the surface of a zinc-based plated steel sheet or a blackened zinc-plated steel sheet and drying. The coating amount of this film is preferably in the range of 0.1 to 3 g / m ² by dry film weight. If the adhesion amount is less than 0.1 g / m ² , sufficient corrosion resistance and heat resistance cannot be obtained, and if it exceeds 3 g / m ² , the surface appearance and weldability may be deteriorated.

  Drying is preferably performed in the range of 50 to 200 ° C. in terms of PMT (maximum ultimate plate temperature). When the PMT is lower than 50 ° C., the film formation becomes insufficient and the corrosion resistance is lowered. When the PMT exceeds 200 ° C., thermal decomposition of the organic components contained in the treatment chemical starts, so that various performances including corrosion resistance cannot be obtained.

Hereinafter, the present invention will be described specifically by way of examples and comparative examples of the present invention. In Examples,% is% by mass unless otherwise specified.
1. Preparation of test blackened steel sheet Electric Zn-Ni alloy plated steel sheet (SPCC, 0.8 mm thickness, plating coverage 20 g / m ² per side, Ni content 13%) is black by any of the following methods A blackened steel sheet was prepared.

a: anodizing treatment,
b: Anodizing treatment + sulfuric acid dipping treatment,
c: Alternating electrolytic treatment.

2. Components of processing chemicals
For each of the components (A) to (F), one or more selected from the following were used.
(A) Polyolefin-based resin Al: Ethylene / acrylic acid copolymer resin having an ethylene / acrylic acid monomer mass ratio of 80/20 (molecular weight 20,000, solid content 25%),
A2: Ethylene / acrylic acid copolymer resin having an ethylene / acrylic acid monomer mass ratio of 85/15 (molecular weight 20,000, solid content 25%);
All of the above resins are self-emulsifying and dispersible (resins that become water-dispersible by distributing carboxyl groups, which are hydrophilic groups in the resin, at the interface).

For comparison, the following acrylic resin was used instead of the polyolefin resin:
A3: copolymer resin having a monomer weight ratio of styrene / butyl acrylate / acrylic acid of 30/40/10 (molecular weight 20,000, solid content 25%),
A4: 2-hydroxyethyl acrylate / methacrylic acid monomer weight ratio 90/10 copolymer resin (molecular weight 20,000, solid content 25%).

(B) Metal compound Bl: ammonium hexafluorozirconate [(NH ₄ ) ₂ ZrF ₆ ],
B2: Zirconium carbonate / potassium {K ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ]},
B3: Ammonium zirconium carbonate {(NH ₄ ) ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ]},
B4: vanadyl sulfate aqueous solution,
B5: ammonium metavanadate
B6: ammonium hexafluorotitanate [(NH ₄ ) ₂ TiF ₆ ],
B7: Hexafluorotitanium hydroacid [H ₂ TiF ₆ ].

(C) Colloidal silica C1: Colloidal silica (ammonia stabilization treatment, particle size 10-20 nm),
C2: colloidal silica (aluminized coating, particle size 10-20 nm),
C3: Colloidal silica (pure silica colloidal solution, particle size 10-20 nm).

(D) Chelate-forming organic compound D1: citric acid,
D2: tartaric acid
D3: Ethylenediamine.

(E) Inorganic acid or its salt E1: Phosphoric acid,
E2: diammonium hydrogen phosphate,
E3: ammonium fluoride.

(F) Silane coupling agent F1: Vinyltrimethoxysilane,
F2: γ-mercaptopropyltrimethoxysilane,
F3: γ-glycidoxypropylmethyldiethoxysilane.

3. Preparation of treatment chemicals The components (A) to (F) selected from the above were mixed in the proportions shown in Table 2, and the concentrations were adjusted with deionized water. Examples 1 to 16 and Comparative Example 1 ~ 7 water treatment chemicals were prepared.

4. Processing method
(1) Degreasing Test blackened Zn-Ni alloy plated steel sheet using alkaline degreasing agent Pulclean N364S (manufactured by Nihon Parkerizing Co., Ltd.), concentration 20 g / L, temperature 60 ° C, spray for 10 seconds (spray pressure 50 kPa), degreased, spray-washed with pure water, and dried.

(2) Application and drying of treatment chemical A predetermined treatment chemical was applied with a roll coater and heated at various temperatures without being washed with water to dry the coating film. The film thickness of the film was adjusted by the solid content of the treatment agent (residue on heating) and coating conditions (rolling force of roll, rotational speed, etc.).

5. Evaluation Method Table 3 shows the results of tests of quality performance (film appearance, corrosion resistance, heat resistance, conductivity, fingerprint resistance, alkali resistance) of the obtained surface-treated steel sheet. The film performance was evaluated as follows.

(1) Film appearance For each sample, the film appearance (with or without unevenness) was visually evaluated. The evaluation criteria are as follows:
○: Uniform appearance with no unevenness,
Δ: Appearance in which unevenness is slightly noticeable,
X: Appearance in which unevenness is conspicuous.

(2) Corrosion resistance Each sample was subjected to a salt spray test (JIS-Z-2371) and evaluated by the white rust area ratio after 240 hours. The evaluation criteria are as follows:
◎: White rust area ratio less than 5%,
○: White rust area ratio 5% or more, less than 10%,
○-: White rust area ratio 10% or more, less than 25%,
Δ: White rust area ratio 25% or more, less than 50%,
X: White rust area ratio 50% or more.

(3) Heat resistance Each sample was held at 200 ° C for 100 hours using an electric furnace, the change in color tone L * a * b * before and after that was measured with a spectroscopic color difference meter, and ΔE calculated by the following formula * Evaluated with:
ΔE * = {(ΔL *) ² + (Δa *) ² + (Δb *) ² } ^1/2
Here, ΔL *, Δa *, Δb * are the difference between the CIE1976 brightness L * and the color coordinates a *, b * of the two object colors in the L * a * b * display system specified in JIS Z8729. is there.

The evaluation criteria are as follows:
○: ΔE * ≦ 3,
Δ: 3 <ΔE * ≦ 5,
X: ΔE *> 5.

(4) Conductivity
The interlayer insulation resistance value was measured according to JIS C2550. The evaluation criteria are as follows:
○: Less than 3 Ω · cm ² / sheet,
Δ: 3 Ω · cm ² / sheet or more, less than 5 Ω · cm ² / sheet,
×: 5 Ω · cm ² / sheet or more.

(5) Fingerprint resistance The sample was immersed in an artificial fingerprint solution having the composition shown in Table 1 below, and the color difference ΔE * before and after immersion was determined in the same manner as described above to determine the fingerprint resistance. The evaluation criteria are as follows:
A: ΔE * ≦ 1,
○: 1 <ΔE * ≦ 3,
X: ΔE *> 3.

(6) Alkali resistance The sample was immersed in an alkaline degreasing agent N364S (50 g / L) manufactured by Nihon Parkerizing Co., Ltd. at 60 ° C. for 120 seconds, and the presence or absence of change in the surface appearance of the sample after immersion was evaluated. The evaluation criteria are as follows.

A: No change in appearance, remaining film,
○: slight unevenness in appearance, film remaining,
Δ: Uneven appearance, part of the film peeled off,
X: Unevenness in appearance, most of the film peeled off.

  As is apparent from the results shown in Table 3, in Examples 1 to 21 using the treatment liquids 1 to 15 according to the present invention, the film appearance, corrosion resistance, heat resistance, conductivity, fingerprint resistance, and alkali resistance were improved. Both were excellent. In particular, the performance of the treatment liquids of Examples 16 to 21 was remarkably excellent.

  On the other hand, in Comparative Examples 1 to 5 using the treatment liquids 16 to 20 that do not satisfy the requirements for the surface treating agent of the present invention, all of the film appearance, corrosion resistance, heat resistance, conductivity, and fingerprint resistance are satisfied. There was nothing, either one was inferior. Further, Comparative Example 6 in which the film thickness of the surface treatment film was thin was inferior in white rust resistance, while Comparative Example 7 in which the film thickness was thick was considerably inferior in conductivity. Comparative Examples 8 to 10 are examples using treatment liquids 21 to 23 in which the resin component (A) is acrylic and not polyolefin. In other respects, the requirements of the present invention were satisfied, but none of them satisfied all the performance.

Claims (8)

  (A) Water-soluble or water-dispersible polyolefin resin 50 to 80% by mass, (B) 5 to 15% by mass of at least one water-soluble metal compound containing a metal selected from zirconium, vanadium and titanium, (C) Colloidal silica 10-30% by mass, (D) 0.5-5% by mass of chelate-forming organic compound, and (E) 0.5-10% by mass of at least one compound selected from inorganic acids and water-soluble salts thereof. An aqueous treatment agent for metal surfaces that has a non-volatile component and does not contain chromium.   (A) Water-soluble or water-dispersible polyolefin resin 50 to 80% by mass, (B) 5 to 15% by mass of at least one water-soluble metal compound containing a metal selected from zirconium, vanadium and titanium, (C) 10-30% by weight of colloidal silica, (D) 0.5-5% by weight of a chelate-forming organic compound, (E) 0.5-10% by weight of at least one compound selected from inorganic acids and water-soluble salts thereof, and ( F) An aqueous treatment agent for metal surfaces having a non-volatile component consisting of 10% or less of a silane coupling agent and not containing chromium. The aqueous treatment chemical according to claim 1 or 2, wherein the polyolefin resin (A) is an ethylene-acrylic acid copolymer resin.   The metal-based aqueous treatment agent according to claim 3, wherein the ethylene / acrylic acid copolymer resin has an ethylene / acrylic acid monomer ratio of 85/15 to 75/25 in terms of mass ratio.   The aqueous surface treatment agent for a metal surface according to any one of claims 1 to 4, wherein the pH of the aqueous treatment agent is 7 to 10. A coating formed by applying and drying the aqueous treatment agent according to any one of claims 1 to 5 on a plated surface of a zinc-nickel alloy-plated steel sheet at a dry coating weight of 0.1 to 3 g / m ^2. A surface-treated steel sheet. A coating film formed by applying and drying the aqueous treatment agent according to any one of claims 1 to 5 on a plated surface of a blackened zinc-based alloy-plated steel sheet, having a dry coating weight of 0.1 to 3 g / m ² A surface-treated steel sheet characterized by comprising:   The surface-treated steel sheet according to claim 7, wherein the zinc-based alloy-plated steel sheet is a zinc-nickel-based alloy-plated steel sheet.