JP4719662B2 - Water-based surface treatment agent for environment-friendly precoat metal material, surface treatment metal material, and environment-friendly precoat metal material - Google Patents

Description

  The present invention relates to a non-chromium aqueous surface treatment agent useful as a base treatment agent for producing a precoat metal material having excellent paint adhesion, corrosion resistance, and coin scratch resistance, as well as a surface treatment metal material and an environment-friendly precoat metal material. .

  Conventional post-painted products that have been painted after processing on parts for home appliances, building materials, automobiles, etc. have been subjected to many pre-treatments such as phosphates. Instead of pretreatment, precoated metal sheets coated with a colored organic film have been used. This metal plate is obtained by coating an organic film on a metal plate or a plated metal plate that has been subjected to a base treatment, and has characteristics that it has workability and good corrosion resistance while having an aesthetic appearance.

  For example, Patent Document 1 discloses a pre-coated steel sheet in which end face corrosion resistance is improved by applying a specific chromate treatment liquid and drying without washing. Pre-coated steel sheets with such chromium-containing ground treatment have corrosion resistance and workability and paint adhesion due to the combined effects of chromate treatment and organic coating, and omit post-processing coating to improve productivity. It is intended for quality improvement and is currently used for general purposes. However, due to the toxicity problem of hexavalent chromium that may be eluted from the chromate-treated film and the organic film containing the chromium-based rust-preventive pigment, recently there has been a growing demand for non-chromium anti-rust treatment and non-chromium organic film.

  The first characteristic required for the pretreatment of the precoated steel sheet is paint adhesion, and it is required to adhere well to both of the two interfaces with the underlying metal as the lower layer and the primer as the upper layer. This coating adhesion may be evaluated after being immersed in boiling water for a predetermined time. This is particularly called secondary coating adhesion, and is distinguished from coating primary adhesion which is coating adhesion before being immersed in boiling water. Both the primary and secondary adhesion properties are extremely important characteristics essential for pre-coated steel sheets that are premised on being processed into complicated shapes by post-processing. The T-bending test is an extremely severe test and is used for evaluating the adhesion of precoated steel sheets.

  As a second characteristic required for the pretreatment of the precoated steel sheet, there is a coin scratch resistance. This is a characteristic influenced not only by adhesion but also by the film hardness of the ground treatment.

  The third characteristic required for the pretreatment of the precoated steel sheet is corrosion resistance. In the case of a pre-coated steel plate, usually, a base treatment, a primer coating treatment, and a top coat coating treatment are sequentially performed on the steel plate. In the case of a precoated steel sheet subjected to conventional chromate treatment, chromate is contained not only in the base treatment layer but also in the primer layer. In particular, the primer layer, which is used as thick as 3 to 10 μm, contains many chromium components as anti-corrosion pigments, as compared to the base treatment that is not normally used exceeding 0.5 μm, and plays a major role in imparting corrosion resistance to precoated steel sheets. Is responsible. However, the actual condition is that the primer in the precoated steel sheet not containing chromium can only provide corrosion resistance that does not reach the primer containing the chromium-based rust preventive pigment. Therefore, it can be said that in the non-chromate pre-coated steel sheet, the base treatment part plays a role of imparting corrosion resistance rather than the conventional chromate system.

  As a non-chromium-based antirust treatment method that replaces chromate treatment, Patent Document 2 describes that white rust resistance and paint adhesion can be achieved by surface-treating zinc and a zinc alloy with an aqueous solution containing tannic acid and a silane coupling agent. Although the technique to improve is disclosed, by this method, the coin scratch resistance and corrosion resistance required for the precoated metal sheet cannot be sufficiently ensured. Patent Document 3 discloses that a chemical conversion film containing silica fine particles and a binder such as polyacrylic acid is formed on the surface of a galvanized steel sheet. However, with this method, the paint adhesion and corrosion resistance required for the precoated steel sheet are not as good as those when the chromate treatment is performed.

  Patent Document 4 discloses a technique for imparting primary rust prevention by surface-treating the surface of a galvanized steel sheet with an aqueous solution containing silica fine particles, a silane coupling agent, and a resin composition. However, when this treatment agent is diverted to a precoated steel sheet, the performance as a coating base for a precoated steel sheet that requires strict adhesion is not sufficient. The adhesion achieved by the treatment solution for imparting temporary rust resistance is the Erichsen extrusion level processing adhesion, and the level of processing adhesion that passes the T-bending test is not achieved. The same can be said for a case where a fingerprint-resistant chemical or a lubricating chemical is diverted to the pretreatment steel sheet surface treatment agent, and it cannot withstand a strict T-bending adhesion test.

  In Patent Document 5, the surface of a plated steel sheet is treated with an aqueous solution containing water-dispersible silica, a silane coupling agent, a zirconium compound or a titanium compound, a thiocarbonyl group-containing compound, an acrylic resin and phosphoric acid. Processing techniques are disclosed. The inhibitory action by the thiocarbonyl group-containing compound and phosphoric acid is insufficient, and it is not as good as the chromate-treated precoated steel sheet in terms of the corrosion resistance as the precoated steel sheet, particularly the corrosion resistance of the end face.

In Patent Document 6, although not a plated steel sheet, a steel substrate is immersed in a treatment warm bath containing a silane coupling agent and ammonium molybdate, and then washed with water to form a reaction-treated undercoat, and an anticorrosion coating treatment as an upper layer. A method for producing an anticorrosion-coated steel material is disclosed. This technique cannot be applied to precoated steel sheets because it requires immersion and water washing steps. In Patent Document 7, the surface of a plated steel sheet such as a galvanized steel sheet is coated with an aluminum salt, a boron compound, a salt of a metal other than aluminum, and SiO ₂ , SnO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, Al. A technique is disclosed in which at least one sol or powder of ₂ O ₃ , ZrO ₂ and Sb ₂ O ₅ is treated with a solution obtained by dissolving or dispersing in water to impart corrosion resistance and coating adhesion. However, even with this technique, it cannot withstand the paint adhesion of precoated steel sheets.
Japanese Patent Laid-Open No. 3-100180 JP 59-116381 A JP 2002-80979 A JP 2001-164195 A JP 2001-316845 A JP 2003-34881 A JP 2005-256156 A

  The present invention is an aqueous surface treatment agent that is excellent in coating adhesion, corrosion resistance, and coin scratch resistance of a coating film when used as a coating base in a pre-coated steel sheet while being an environment-friendly non-chromium system, and using the same It is an object of the present invention to provide a surface-treated metal material and an environment-friendly pre-coated metal material that is excellent in coating adhesion, corrosion resistance, and coin scratch resistance.

The above issues
(1) Silane coupling agent (A), metal oxide sol (B), metal compound (C) and water-dispersible silica (D) are contained, and metal compound (C) is V compound, W compound, Mo A compound, an Al compound, an Sn compound, an Nb compound, an Hf compound, a Y compound, an Ho compound, a Bi compound, an La compound, a Ce compound, and a Zn compound, and the components (A) and (B) The ratio of (B) / (A) is 1/50 to 10/1 as the solid content mass ratio, and the ratio of component (A) to component (C) is (C) / (A) solid The mass ratio is in the range of 1/1000 to 4/10, and the ratio of the component (A) to the component (D) is 1/50 to 10/1 as the solid mass ratio of (D) / (A). An aqueous surface treatment agent for environmentally friendly pre-coated metal materials that is in the range of
(2) At least the metal oxide sol (B) is selected from zirconium oxide sol, cerium oxide sol, aluminum oxide sol, tin oxide sol, niobium oxide sol, zinc oxide sol, antimony oxide sol, bismuth oxide sol, yttrium oxide sol and holmium oxide sol 1 type of aqueous surface treating agent of the above (1);

(3) The aqueous surface treating agent according to (1) or (2) above, wherein at least 5% by mass of the silane coupling agent (A) is a silane coupling agent having an amino functional group;
(4) Equivalent ratio of silane coupling agent (A) between the silane coupling agent containing an amino functional group and the silane coupling agent having an epoxy group bonded to an adjacent carbon atom is 50: 1 to 1:50. The aqueous surface treating agent according to (1) or (2), which is a mixture of
(5) A metal film having a dry film of 0.01 to 1 g / m ² on its surface, which is a dry film from the aqueous surface treating agent according to any one of (1) to (4) above; and (6 This is achieved by an environment-friendly pre-coated steel sheet in which an upper layer film not containing chromium is further formed on the surface of the metal material of (5).

  The pre-coated metal material obtained by applying an upper layer coating not containing chromium to the metal material treated with the water-based surface treatment agent for the environment-friendly pre-coated metal material of the present invention, even though the coating layer does not contain chromium. , Corrosion resistance, paint adhesion (primary paint adhesion and paint secondary adhesion after T-bending test) and excellent coin scratch resistance. Therefore, the present invention has extremely high industrial value. The precoated metal material of the present invention is also excellent in moisture resistance and chemical resistance (alkali resistance and acid resistance).

The present invention is described in detail below.
The aqueous surface treatment agent of the present invention comprises a silane coupling agent (A), a metal oxide sol (B), a V compound, a W compound, a Mo compound, an Al compound, a Sn compound, an Nb compound, an Hf compound, and a Y compound. And at least one metal compound (C) selected from the group consisting of Ho compound, Bi compound, La compound, Ce compound and Zn compound, and water-dispersible silica (D) in a specific mutual ratio.

  The silane coupling agent (A) has high -OH activity of silanol groups generated by hydrolysis, and has a strong chemical bond of -Si-OM through the base metal M as a base material and oxygen atoms. do. This chemical bond particularly contributes to good adhesion to the base metal. Moreover, the reaction with the organic functional group contained in the upper layer may also contribute to improving the adhesion with the upper layer. When a polar group having strong polar O, N or the like as a constituent element is introduced as a functional group of the silane coupling agent, the adhesion to the upper layer is further improved.

  Examples of silane coupling agents applicable to the present invention include N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, and N-β (aminoethyl). γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxy Silane, N-phenyl-γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane , N β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (N-vinylbenzylamino) Ethyl) -γ-aminopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyl Dimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercapto Propylmethyldimethoxysilane, γ-mel Captopropyltriethoxysilane, γ-mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloro Propylmethyldimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropylmethyldiethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropyl Triethoxysilane, γ-anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysila , Octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, octadecyldimethyl [3- (methyldimethoxysilyl) propyl] ammonium chloride, octadecyldimethyl [3- (triethoxysilyl) propyl] ammonium chloride, octadecyldimethyl [3 -(Methyldiethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane and the like. Among these, only one component or a combination of a plurality of components can be used.

  In many cases, the surface treatment agent is somewhat compatible with the primer applied to the upper layer, and depending on the combination, the performance may not appear as expected. Among the above coupling agents, those having an amino functional group are not easily affected by compatibility with the upper layer. Therefore, in the aqueous surface treatment agent (primary treatment agent) of the present invention, it is preferable that the silane coupling agent (A) contains at least one having an amino functional group. Here, in the present invention, the amino functional group means at least one functional group selected from a primary amino group and a secondary amino group. The amino functional group has a relatively high reaction activity in either an acidic medium or a basic medium. That is, among organic functional groups with active hydrogen, amino functional groups have relatively high reactivity (nucleophilicity, basicity), depending on the acid basicity of the solution and the substituents adjacent to the functional group. Have Silane coupling agents with amino functional groups are highly reactive with amino functional groups, so they react with the functional groups (ester groups, epoxy groups, etc.) of the resins that make up the upper layer primer and have good paint adhesion. Expresses sex. Water resistance, chemical resistance (alkali, acid), moisture resistance, etc. may be improved as a combined effect that the effect of improving the coating adhesion is higher than other silane coupling agents. . Of the silane coupling agents having an amino functional group, those having one amino functional group per molecule of the silane coupling agent are preferred. The use amount of the silane coupling agent having an amino functional group with respect to the entire silane coupling agent (A) is preferably 5% by mass or more based on the solid content from the viewpoint of expressing higher coating adhesion. It is more preferably 10% by mass or more, and still more preferably 20% by mass or more.

When two or more types are used as the silane coupling agent (A), a functional group capable of reacting with a silane coupling agent having an amino functional group and an amino functional group, for example, an epoxy group (glycidyl bonded to an adjacent carbon atom) It is preferable to use a silane coupling agent having a group, 3,4-epoxycyclohexyl group or the like. The use ratio of these silane coupling agents does not need to be an amount in which each functional group reacts without excess or deficiency, and a silane coupling agent having an amino functional group and a functional group capable of reacting with the amino functional group The equivalent ratio is preferably in the range of 50: 1 to 1:50, more preferably in the range of 10: 1 to 1:10, adjacent to the silane coupling agent having an amino functional group. In the case of use in combination with a silane coupling agent having an epoxy group bonded to a carbon atom, the corrosion resistance can be further improved in addition to the effect on the coating adhesion by the silane coupling agent having an amino functional group.
In addition, when using a some silane coupling agent, after mixing both, it is good to mix with another component.

The aqueous surface treating agent of the present invention contains a metal oxide sol (B). The metal oxide sol (B) contributes to improvement in adhesion from the viewpoint of introduction of a polar group. However, excessive addition makes it easy for the water to enter the interface, and the secondary coating adhesion may be reduced. Further, the metal oxide sol (B) increases the hardness of the base film and contributes to the improvement of the coating adhesion, so that it effectively acts on the improvement of the coin scratch resistance. In addition, the metal oxide sol (B) effectively works to improve chemical resistance, and particularly effectively works to improve alkali resistance.
The metal oxide sol is preferably at least one selected from zirconium oxide sol, cerium oxide sol, aluminum oxide sol, tin oxide sol, niobium oxide sol, zinc oxide sol, antimony oxide sol, bismuth oxide sol, yttrium oxide sol and holmium oxide sol. More specifically, ZrO ₂ sol (zirconia sol), TiO ₂ sol (titania sol), CeO ₂ sol, Al ₂ O ₃ sol (alumina sol), SnO ₂ sol, NbO sol, ZnO sol, Sb ₂ O ₅ sol Bi ₂ O ₃ sol, Y ₂ O ₃ sol, Ho ₂ O ₃ sol, and the like.

  The particle diameter of the metal oxide sol particles used in the present invention is preferably 1 to 1000 nm, more preferably 1 nm to 500 nm, and even more preferably 1 nm to 100 nm as the primary particle diameter. . These metal oxide particles may have secondary aggregation and tertiary aggregation to have a secondary particle size and a tertiary particle size, but they may be stably dispersed in water even when they are aggregated. When the primary particle diameter is less than 1 nm, the stability of the processing agent is deteriorated, for example, thixotropy appears. Moreover, when it exceeds 1000 nm, bending adhesiveness will deteriorate.

  The content of the metal oxide sol (B) needs to be in the range of 1/50 to 10/1 as the solid content mass ratio of (B) / (A) to the silane coupling agent (A). And preferably in the range of 1/30 to 4/1, more preferably in the range of 1/10 to 2/1. When the content is less than 1/50, chemical resistance and corrosion resistance tend to decrease, and when it exceeds 10/1, chemical resistance tends to decrease.

Commercially available products of the metal oxide sol (B) used in the present invention include nano-use ZR40BL, nano-use ZR30BS, nano-use ZR30BH, nano-use ZR30AL, nano-use ZR30AH (manufactured by Nissan Chemical Co., Ltd.), ZSL-20N, ZSL- 10T, ZSL-10A (Daiichi Rare Element Chemical Co., Ltd.), YSL-10 (Daiichi Rare Element Chemical Co., Ltd.) as yttrium sol, Tin Oxide sol (Daiichi Rare Element Chemical Co., Ltd.) as tin sol SBSL-50 as an antimony sol (manufactured by Daiichi Rare Elemental Chemical Co., Ltd.), CESL-15N (manufactured by Daiichi Rare Elemental Chemical Co., Ltd.) as a cerium sol, and Nanotek Bi ₂ O ₃ (manufactured by CI Kasei Co., Ltd.) as a bismuth sol ), Nanotek Ho ₂ O as Horoniumuzoru (CI Kasei Co., Ltd.), (manufactured by CI Kasei Co.) NanoTek TiO ₂ as a titania sol (manufactured by CI Kasei Co.) NanoTek ZnO as zinc sol, alumina sol 100 as the alumina sol, alumina sol 200, Alumina Sol 520 (Nissan chemical Co.), manufactured by NanoTek Al ₂ O ₃ (CI Kasei Co.) and the like.

  The aqueous surface treating agent of the present invention contains a metal compound (C). The metal compound (C) is at least one selected from V compound, W compound, Mo compound, Al compound, Sn compound, Nb compound, Hf compound, Y compound, Ho compound, Bi compound, La compound, Ce compound and Zn compound. It is. The metal compound (C) acts as an inhibitor (corrosion inhibitor) and improves the corrosion resistance. The mechanism for improving the corrosion resistance of the metal compound (C) is not clear, but it seems that the point is that it can take several valences. Moreover, when there is no valence change, the presence form as a heteropolyacid may be taken by the change of pH. The heteropolyacid may modify the conventional action by a physical or chemical action on the silane coupling agent (A) or the metal oxide sol (B) in the surface treatment agent. Therefore, in addition to improving corrosion resistance, chemical resistance, moisture resistance, and the like may be improved.

Examples of the metal compound (C) include carbonates, oxides, hydroxides, nitrates, sulfates, phosphates, fluorides, fluoroacids or salts thereof, oxoacid salts, and organic acid salts of the above metals. . When the metal compound (C) is an oxide, it is excluded from the sol form.
Specific examples of the V compound include vanadium pentoxide (V), vanadium trioxide (III), vanadium dioxide (IV), vanadium hydroxide (II), vanadium hydroxide (III), vanadium sulfate (II), Vanadium sulfate (III), vanadium oxysulfate (IV), vanadium fluoride (III), vanadium fluoride (IV), vanadium fluoride (V), vanadium trichloride VOCl ₃ , vanadium trichloride VCl ₃ , hexafluorovanadium Acid (III) or salt thereof (potassium salt, ammonium salt, etc.), metavanadic acid (V) or salt thereof (sodium salt, ammonium salt, etc.), vanadyl acetylacetonate (IV) VO (OC (= CH ₂ ) CH ₂ COCH _{3) 2,} vanadium acetylacetonate (II _{) V (O-C (=} CH 2) CH 2 COCH 3) 3, phosphovanadomolybdic acid _{H 15-X [PV 12-} X MoO 40] · nH 2O (6 <X <12, n <30) and Can be mentioned.

As the W compound, tungsten oxide (IV), tungsten oxide (V), tungsten oxide (VI), tungsten fluoride (IV), tungsten fluoride (VI), tungstic acid (VI) H ₂ WO ₄ or a salt thereof ( Ammonium salt, sodium salt, etc.), metatungstic acid (VI) H ₆ [H ₂ W ₁₂ O ₄₀ ] or a salt thereof (ammonium salt, sodium salt, etc.), paratungstic acid (VI) H ₁₀ [W ₁₂ O ₄₆ H ₁₀ ] or a salt thereof (ammonium salt, sodium salt, etc.).
Examples of the Mo compound include phosphovanadomolybdic acid H _15-X [PV _12-X MoO ₄₀ ] .nH _{2 O} (6 <X <12, n <30), molybdenum oxide, molybdate H ₂ MoO ₄ , ammonium molybdate, Ammonium paramolybdate, sodium molybdate, molybdophosphoric acid compounds (for example, ammonium molybdate (NH ₄ ) ₃ [PO ₄ Mo ₁₂ O ₃₆ ] · 3H ₂ O, sodium molybdophosphate Na ₃ [PO ₄ Mo ₁₂ O ₃₆ ] · nH ₂ O and the like.

Examples of the Al compound include aluminum nitrate, aluminum sulfate, potassium aluminum sulfate, sodium aluminum sulfate, ammonium aluminum sulfate, aluminum phosphate, aluminum carbonate, aluminum oxide, and aluminum hydroxide; Sn compounds include tin (IV) oxide and stannic acid. Sodium Na ₂ SnO ₃ , tin (II) chloride, tin (IV) chloride, tin (II) nitrate, tin (IV) nitrate, ammonium hexafluorostannate (NH ₄ ) SnF _{6 and the} like; Examples include niobium (Nb ₂ O ₅ ), sodium niobate (NaNbO ₃ ), niobium fluoride (NbF ₅ ), ammonium hexafluoroniobate (NH ₄ ) NbF _{6, and the} like.

Examples of the Hf compound, Y compound, Ho compound, Bi compound, and La compound include hafnium oxide, hexafluorohafnium hydrogen acid, yttrium oxide, yttrium acetylacetonate, holmium oxide, bismuth oxide, and lanthanum oxide.
Examples of the Ce compound include cerium oxide, cerium acetate Ce (CH ₃ CO ₂ ) ₃ , cerium (III) or (IV) nitrate, cerium ammonium nitrate, cerium sulfate, cerium chloride, etc .; Zn compounds include zinc oxide, hydroxide Zinc, zinc acetate, zinc nitrate, zinc sulfate, zinc chloride, sodium zincate and the like can be mentioned.

The content of the metal compound (C) needs to be in the range of 1/1000 to 4/10 as the solid content mass ratio of (C) / (A) to the silane coupling agent (A). The range is preferably 1/300 to 2/10, and more preferably 1/100 to 1/10. When the content is less than 1/1000, the corrosion resistance improving effect does not occur, and when it exceeds 4/10, depending on the type of primer applied to the upper layer, the coating secondary adhesion may be deteriorated. is there.
In addition, when the liquid stability of the treatment agent is deteriorated due to the addition of the metal compound (C), carboxylic acid such as acetic acid, propionic acid, oxalic acid, gluconic acid, tartaric acid, malic acid, ascorbic acid, tannic acid, etc. The liquid stability can be improved by appropriately adding.

The aqueous surface treating agent of the present invention contains water-dispersible silica (D). Water-dispersible silica (D) contributes to improvement in adhesion from the viewpoint of introduction of polar groups. However, excessive addition also facilitates the penetration of water into the interface, which may reduce the coating secondary adhesion. Further, the water dispersible silica (D) increases the hardness of the base film and contributes to the improvement of the coating adhesion, and thus effectively acts to improve the coin scratch resistance.
The water-dispersible silica (D) includes gas-phase silica produced by a gas-phase reaction and liquid-phase silica produced in a state dispersed in water by a liquid-phase reaction, and both can be used.

  The particle diameter of the water-dispersible silica (D) used in the present invention is preferably 1 to 100 nm, more preferably 2 to 50 nm as the primary particle diameter. These water-dispersible silica (D) may have secondary and tertiary agglomeration to have a secondary particle size and a tertiary particle size, but they may be dispersed stably in water even if they are agglomerated. When the primary particle diameter is less than 1 nm, the stability of the processing agent is deteriorated, for example, thixotropy appears. Moreover, when it exceeds 100 nm, bending adhesiveness will deteriorate.

  The content of the water-dispersible silica (D) needs to be in the range of 1/50 to 10/1 as the solid content mass ratio of (D) / (A) to the silane coupling agent (A). And preferably in the range of 1/30 to 4/1, more preferably in the range of 1/10 to 2/1. When the content is less than 1/50, the coating adhesion and the coin scratch resistance tend to decrease, and when it exceeds 10/1, the chemical resistance tends to decrease.

  Commercially available water-dispersible silica (D) used in the present invention includes SNOWTEX C, SNOWTEX O, SNOWTEX N, SNOWTEX NXS, SNOWTEX OS, SNOWTEX OUP, SNOWTEX OL as liquid phase silica. Snowtex PS-MO, Snowtex PS-S, Snowtex S, Snowtex UP, Snowtex PS-M, Snowtex PS-L, Snowtex 20, Snowtex 30, Snowtex 40 (all are Nissan Chemical Industries ( As the gas phase silica, there may be mentioned Aerosil 50, Aerosil 130, Aerosil 200, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil MOX80, Aerosil MOX170 (all manufactured by Nippon Aerosil Co., Ltd.). Of these, only one component or a combination of two or more can be used.

  From the viewpoint of dispersion stability, an acid or a base may be appropriately added to the water-dispersible silica (D) used in the present invention. The acid may be any of an inorganic acid and an organic acid, and examples thereof include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and acetic acid. Examples of the base include sodium hydroxide, potassium hydroxide, calcium hydroxide, and aluminum hydroxide.

The pH of the aqueous surface treating agent of the present invention is preferably 3 to 10, and more preferably 5 to 9. In particular, when the silane coupling (A) having an amino functional group is used, the pH is preferably 7-9.
An appropriate acid (eg, acetic acid, phosphoric acid, etc.) or alkali (eg, ammonia, organic amine, etc.) may be added to the aqueous surface treatment agent of the present invention in order to control the pH of the treatment agent.

  The water-based surface treatment agent of the present invention is a water-soluble resin for softening the treated film, a surfactant called a wettability improver for obtaining a uniform film on the coated surface, a thickener, and an improvement in weldability. Therefore, it may contain a conductive material for coloring, a coloring pigment for improving the designability, and the like.

The medium of the aqueous surface treatment agent of the present invention is water. Although there is no restriction | limiting in particular about the total solid content density | concentration in the aqueous surface treating agent of this invention, It is preferable that a total solid content density | concentration is about 1-20 mass% in consideration of coating-film formation property and operativity.
The aqueous surface treating agent of the present invention comprises a silane coupling agent (A), a metal oxide sol (B), a metal compound (C) and water-dispersible silica (D), and other additives when used. There is no restriction | limiting in particular about the addition order of each component.

  Examples of the metal material to which the aqueous surface treatment agent of the present invention is applied include cold-rolled steel sheet, hot-rolled steel sheet, hot-dip galvanized steel sheet, electrogalvanized steel sheet, hot-dip galvanized steel sheet, aluminum-plated steel sheet, and aluminum-zinc alloy-plated steel sheet. Metal materials including generally known metal plates such as steel plates such as stainless steel plates, aluminum plates, copper plates, titanium plates, magnesium plates, and other plated metal plates can be used.

  Prior to applying the aqueous surface treating agent of the present invention to a metal material, the metal material can optionally be subjected to usual treatments such as hot water washing, alkali degreasing, and surface conditioning.

  The aqueous surface treating agent of the present invention can be applied to a metal material by a usual coating method such as roll coating, curtain flow coating, air spray, airless spray, dipping, bar coating, brush coating, and the like. Although it dries after application | coating, there is no restriction | limiting in particular in a drying method, drying temperature, and drying time, What is necessary is just the temperature and time which a water | moisture content evaporates. For example, what is necessary is just to dry by making the highest achieved temperature of metal materials, such as the apply | coated metal plate, into 60-120 degreeC in oven.

The coating amount of the aqueous surface treatment agent of the present invention is required to be in the range of 0.01 to 1 g / m ² as a dry film amount, and in the range of 0.02 to 0.4 g / m ^2. Is more preferable, and the range of 0.05 to 0.2 g / m ² is more preferable. If the coating amount is less than 0.01 g / m ² , the coating amount is too small, and the coating amount varies depending on the part, and the adhesion (adhesion to the metal material and the upper layer) tends to be insufficient. On the other hand, when the coating amount exceeds 1 g / m ² , the coating adhesion tends to be insufficient, and the cost is disadvantageous.

  The treatment with the aqueous surface treatment agent of the present invention is usually performed as a ground treatment in a pre-coated metal material as described below, but can also be carried out as a ground treatment in a laminated steel sheet.

  The invention also relates to a precoated metal material. The precoat metal material of the present invention can be obtained by forming an upper film layer not containing chromium on a film formed by applying the aqueous surface treating agent of the present invention to a metal material and drying it. The upper film layer is usually composed of a non-chromate primer layer and a top coat layer formed on the non-chromate primer layer (the top coat layer usually does not contain chromium), and the upper film layer is the aqueous surface treatment agent of the present invention. It can be formed by applying a non-chromate primer on the film formed by applying and drying and then applying a top coat thereon. Further, the upper film layer may consist of only the top coat layer. In this case, the upper film layer is coated with the top coat on the film formed by applying the aqueous surface treatment agent of the present invention and drying. Can be formed.

  As the non-chromate primer that can be used in the present invention, any primer can be used as long as it does not use a chromate rust preventive pigment during the blending of the primer. The base resin of the non-chromate primer may be in any form such as water, solvent, and powder. Generally known resins such as polyacrylic resins, polyolefin resins, polyurethane resins, epoxy resins, polyester resins, polybutyral resins, melamine resins, etc. may be used as they are or in combination. it can. As rust preventive pigments, generally known ones such as (1) phosphoric acid rust preventive pigments such as zinc phosphate, iron phosphate and aluminum phosphate, (2) calcium molybdate, ammonium molybdate, barium molybdate, etc. Molybdic acid-based rust preventive pigments, (3) vanadium-based rust preventive pigments such as vanadium oxide, and (4) finely divided silica such as water-dispersible silica and fumed silica can be used. About the compounding quantity on the solid content standard of each component with respect to the whole non-chromate primer, it is preferable that the compounding quantity on the solid content standard of the rust preventive pigment with respect to the whole non-chromate primer is 1 to 40% by mass. When the blending amount of the rust preventive pigment is less than 1% by mass, the corrosion resistance is not sufficient, and when it exceeds 40% by mass, the workability is lowered.

 The applied film thickness of the primer is preferably 1 to 30 μm in terms of dry film thickness. When the thickness is less than 1 μm, the corrosion resistance decreases, and when it exceeds 30 μm, the adhesion during processing decreases. There are no particular limitations on the baking and drying conditions of the non-chromate primer, and for example, it can be 10 to 5 minutes at 130 to 250 ° C.

The top coat is not particularly limited, and any ordinary top coat for painting can be used. The base resin of the top coat may be in any form such as water, solvent, and powder. Generally known resins such as polyacrylic resins, polyolefin resins, polyurethane resins, epoxy resins, polyester resins, polybutyral resins, melamine resins, etc. may be used as they are or in combination. it can.
Coloring pigments may be added to the top coat, and there are no particular restrictions on the coloring pigments. Titanium white, zinc yellow, alumina white, carbon black, bengara, yellow iron oxide, molybdate orange, zirconium oxide (IV) And inorganic pigments such as Hansa Yellow, pyrazolone orange, and azo pigments. In addition, the top coat may contain the above-mentioned rust preventive pigments as appropriate, and may also contain additives such as antifoaming agents, leveling agents, dispersion aids, and diluents for reducing paint viscosity. Also good.

  The top coat is preferably 3 to 40 μm in dry film thickness. If it is less than 3 μm, the corrosion resistance is lowered, and if it exceeds 40 μm, the adhesion is lowered and the cost is increased. There is no restriction | limiting in particular about the baking drying conditions of the said topcoat, For example, it can be 10 seconds-20 minutes at 160-350 degreeC.

  The application method of the non-chromate primer and the top coat is not particularly limited, and a commonly used dipping method, spray method, roll coat method, air spray method, airless spray method and the like can be used.

Examples of the present invention and comparative examples are given below to specifically describe the present invention.
1. Preparation of test plate 1.1 Test material, electrogalvanized steel sheet (hereinafter symbol: EG)
Plate thickness 0.6mm, plating coverage 20g / m ² per side (double-sided plating)
・ Hot galvanized steel sheet (hereinafter symbol: GI)
Plate thickness 0.6mm, zinc adhesion amount 50g / m ² per one side (double-sided plating)
・ Aluminum-zinc alloy plated steel sheet (hereinafter symbol: GL)
Plate thickness 0.6mm, plating coverage 50g / m ² per side (double-sided plating)

1.2 Pretreatment CL-N364S (manufactured by Nihon Parkerizing Co., Ltd.), which is an alkaline degreasing agent, is used as an aqueous solution having a concentration of 20 g / L and a temperature of 60 ° C. Washed with water and dried.

1.3 Surface Treatment / Examples 1 to 33, Comparative Examples 1 to 18
A surface treatment agent having a composition shown in Tables 1 to 3 is selected on the surface (one side) of the test material after pretreatment, and the test materials are selected as shown in Tables 4 to 6, and a dry film is formed using a roll coater. It apply | coated so that the quantity might be set to 0.1 g / m < ² >, and it dried on the conditions of the ultimate board temperature of 80 degreeC in a hot-air drying furnace.
・ Coating chromate treatment (Comparative Examples 19 and 20)
On the surface (one surface) of the test material after the pretreatment, ZM-1300AN a coating type chromate agent - (Japan Pas mosquito manufactured Rising (Ltd.)), Cr deposition amount using a roll coater and 40 mg / ^{m 2} It was applied so that it was dried in a hot air drying oven under the condition of a reaching plate temperature of 80 ° C.

1.4 Application of undercoat and topcoat The primer and topcoat were applied in the following two combinations on the treated surface of each surface-treated plate prepared in 1.3.
<Upper layer A>: After applying a commercially available primer paint (Dai Nippon Paint Co., Ltd., V Knit # 200) (dry film thickness 5.5 μm), baking at 200 ° C., then top coat paint on the baking surface (Dai Nippon Paint Co., Ltd., V knit # 500) was applied (dry film thickness 17 μm), and baked at 220 ° C. to prepare a test plate.
<Upper layer B>: A commercially available primer coating (Nippon Paint Co., Ltd., Flexcoat 600) was applied (dry film thickness: 5.0 μm), then baked at 200 ° C., and then a top coat coating (Japan) Paint Co., Ltd., Flexcoat 5030) was applied (dry film thickness 15 μm), and baked at 225 ° C. to prepare a test plate.

2. Evaluation Test 2.1 Corrosion Resistance The coating film of each test plate produced was scratched with a cutter to reach a metal substrate, and a salt spray test specified in JIS-Z2371 was performed for 480 hours. The criterion for determination was the film swelling width (maximum value on one side) from the cut part. Moreover, the end surface corrosion resistance measured the coating film swelling width (maximum value) from the end surface.
<Evaluation criteria-Cut part>
◎: Less than 2 mm ○: 2 mm or more and less than 6 mm Δ: 6 mm or more and less than 10 mm x: 10 mm or more <Evaluation Criteria—End Face>
◎: Less than 4 mm ○: 4 mm or more and less than 6 mm □: 6 mm or more and less than 8 mm Δ: 8 mm or more and less than 12 mm x: 12 mm or more

2.2 Bending adhesion test 2.2.1 Primary bending adhesion test (coating primary adhesion)
In accordance with the test method of JIS-G3312, a 2T bending test with two inner spacing plates was performed at 20 ° C. for each test plate, and the peeling state of the coating film after peeling the tape was observed with the naked eye. The coating adhesion was evaluated according to the judgment criteria.
<Evaluation criteria>
◎: No peeling ○: Peeling area less than 10% □: Peeling area 10% or more and less than 50% Δ: Peeling area 50% or more and less than 80% ×: Peeling area 80% or more

2.2.2 Secondary bending adhesion (painting secondary adhesion)
The test plate was immersed in boiling water for 2 hours and then allowed to stand for one day, and then the same test as the primary bending adhesion test was performed. Judgment criteria are as follows.
<Evaluation criteria>
◎: No peeling ○: Peeling area less than 10% □: Peeling area 10% or more and less than 50% Δ: Peeling area 50% or more and less than 80% ×: Peeling area 80% or more

2.3 Coin scratch resistance A 10-yen coin was installed at an angle of 45 ° with respect to each test plate, the coating film was rubbed at a constant speed with a load of 3 kg, and the degree of scratching of the coating film was observed with the naked eye. Coin scratch resistance was evaluated according to the criteria. In addition, in the following evaluation, the part where the primer was exposed by peeling off only the top coat was not included in the exposed area of the substrate as scratches not caused by the base treatment film.
<Evaluation criteria>
◎: 0% of substrate exposure (including the case where only the primer is exposed)
○: Substrate exposure is less than 10% □: Substrate exposure is 10% or more and less than 50% △: Substrate exposure is 50% or more and less than 80% ×: Substrate exposure is 80% or more

2.4 Alkali Resistance After the test plate was immersed in a 5% aqueous sodium hydroxide solution at room temperature for 24 hours, the number of blisters generated and the generation density were evaluated. Judgment criteria are as follows.
：: No blister ○: One blister is 0.2 mm or less and generation density is F.
□: The size of one blister is about 0.2 mm to 1 mm and the generation density is F, or the size of one blister is about 0.2 mm to 0.4 mm and the generation density is M.
Δ: The size of one blister is about 1 mm to 1.5 mm and the generation density is F, the size of one blister is about 0.4 mm to 1 mm and the generation density is M, or 1 The size of one blister is 0.2 mm or less and the generation density is MD.
X: The size of one blister is 1.5 mm or more, the size of the blister is 0.2 mm or more and the generation density is MD, or the generation density is D regardless of the size of the blister.
In the alkali resistance and acid resistance evaluation tests described above, F, M, MD, and D represent the following meanings. F
F: The number of blisters generated is very small.
M: The number of blisters generated is small.
MD: A large number of blisters are generated.
D: The number of blisters generated is very large.

2.5 Acid resistance After the test plate was immersed in a 5% sulfuric acid aqueous solution at room temperature for 24 hours, the number of blisters generated and the generation density were evaluated. Judgment criteria are as follows.
：: No blister ○: One blister is 0.2 mm or less and generation density is F.
□: The size of one blister is about 0.2 mm to 1 mm and the generation density is F, or the size of one blister is about 0.2 mm to 0.4 mm and the generation density is M.
Δ: The size of one blister is about 1 mm to 1.5 mm and the generation density is F, the size of one blister is about 0.4 mm to 1 mm and the generation density is M, or 1 The size of one blister is 0.2 mm or less and the generation density is MD.
X: The size of one blister is 1.5 mm or more, the size of the blister is 0.2 mm or more and the generation density is MD, or the generation density is D regardless of the size of the blister.

2.6 Moisture resistance The coating film of the test plate was scratched to reach the metal substrate with a cutter, and left for 1000 hours in an atmosphere of 98% humidity and 40 ° C. The criterion for determination was the film swelling width (maximum value on one side) from the cut part.
◎: Less than 2 mm ○: 2 mm or more and less than 4 mm □: 4 mm or more and less than 6 mm Δ: 6 mm or more and less than 10 mm x: 10 mm or more

3. Evaluation result The result of the said evaluation test is shown to Tables 4-6. Examples 1 to 33 in Tables 4 and 5 are coating plates (test plates) of a metal material in which a coating film is formed by applying a water-based surface treatment agent of the present invention (Nos. 1 to 29 in Table 1) and then drying. Performance, corrosion resistance (cut portion and end surface corrosion resistance), paint adhesion (primary and secondary after T-bending test), and coin scratch resistance are all good, and chromate of Comparative Examples 19 and 20 The performance was equal to or better than that of the treatment.
In addition, when a silane coupling agent having an amino functional group was used, chemical resistance (alkali resistance and acid resistance) and moisture resistance were superior to when a silane coupling agent having an epoxy group was used. (Comparison between Examples 2 and 5 and Examples 18 and 19). In addition, when a silane coupling agent having an amino functional group and a silane coupling agent having an epoxy group were used in combination, the coating adhesion and coin scratch resistance were particularly excellent compared to the case of using only the former. (Comparison between Example 6 and Examples 31-33).

  On the other hand, No. in Table 3 which is outside the scope of the present invention. 30 and 32 (metal oxide sol (B) and metal compound (C) not used), No. 33 and 35 (use of no silane coupling agent (A) and metal oxide sol (B)), and In Comparative Examples 1 to 6 in Table 6 using an aqueous surface treating agent of 31 and 34 (metal oxide sol (B) and water-dispersible silica (D) not used), corrosion resistance (cut portion and end face corrosion resistance), At least three of coating adhesion (primary and secondary after T-bending test), coin scratch resistance, moisture resistance and chemical resistance (alkali resistance and acid resistance) were inferior. No. In Comparative Examples 7, 8 and 15-18 using the aqueous surface treating agent of 36, 37 and 44 to 47 (the amount of the metal compound (C) used is outside the scope of the present invention), the corrosion resistance (cut portion and end surface corrosion resistance), At least two of coating adhesion (primary and secondary after T-bending test), coin scratch resistance and chemical resistance (alkali resistance and acid resistance) were inferior. Moreover, in the comparative example 9 using the aqueous surface treating agent of No. 38 (the amount of water-dispersible silica (D) used is outside the present invention), corrosion resistance (cut portion and end surface corrosion resistance), moisture resistance and chemical resistance (Alkali resistance and acid resistance) were inferior. Further, in Comparative Examples 10 to 14 using the aqueous surface treating agent of No. 39 to 43 (the amount of the metal oxide sol (D) used is outside the present invention), the corrosion resistance (cut portion and end surface corrosion resistance) and chemical resistance The properties (alkali resistance and acid resistance) were inferior.

Metal oxide sol (B)
Zirconia sol: Nano-use ZR30AL (Nissan Chemical Co., Ltd.)
Y ₂ O ₃ sol: Nanotek Y ₂ O ₃ (manufactured by CI Kasei Co., Ltd.)
CeO ₂ sol: CESL-15N (manufactured by Daiichi Elemental Chemical Co., Ltd.)
SnO ₂ sol: manufactured by Daiichi Elemental Chemical Co., Ltd. ZnO sol: Nanotek ZnO (produced by CII Kasei Co., Ltd.)
Bi ₂ O ₃ sol: Nanotek Bi ₂ O ₃ (Ci Kasei Co., Ltd.)

Metal compound (C)
W: ammonium metatungstate Mo: ammonium molybdate Al: aluminum hydroxide Ce: cerium oxide V: vanadyl acetylacetonate

Water dispersible silica (D)
Liquid phase silica: Snowtex N (manufactured by Nissan Chemical Industries, Ltd.)
Gas phase silica: Aerosil 200 (Nippon Aerosil Co., Ltd.)

Claims (6)

  Silane coupling agent (A), metal oxide sol (B), metal compound (C) and water-dispersible silica (D) are contained, and metal compound (C) is V compound, W compound, Mo compound, Al compound. And the ratio of the component (A) to the component (B) is in the range of 1/50 to 10/1 as the solid content mass ratio of (B) / (A), The ratio of the component (A) to the component (C) is in the range of 1/1000 to 4/10 as the solid content mass ratio of (C) / (A), and the ratio of the component (A) to the component (D) The ratio is in the range of 1/50 to 10/1 as the solid mass ratio of (D) / (A). Corrosion resistance, paint primary adhesion after T-bending test, paint secondary adhesion, and coin scratch resistance. Aqueous surface treatment as a surface treatment to obtain an excellent environmentally friendly pre-coated metal material A is, components the component for achieving the above effects (A), (B), said treating agent consisting only of (C) and (D).   The metal oxide sol (B) is at least one selected from zirconium oxide sol, cerium oxide sol, aluminum oxide sol, tin oxide sol, niobium oxide sol, zinc oxide sol, antimony oxide sol, bismuth oxide sol, yttrium oxide sol and holmium oxide sol. The water-based surface treatment agent according to claim 1.   The aqueous surface treating agent according to claim 1 or 2, wherein at least 5% by mass of the silane coupling agent (A) is a silane coupling agent having an amino functional group.   The silane coupling agent (A) is a mixture having an equivalent ratio of 50: 1 to 1:50 of a silane coupling agent containing an amino functional group and a silane coupling agent having an epoxy group bonded to an adjacent carbon atom. The aqueous surface treating agent according to claim 1 or 2. A dry film from the aqueous surface treatment agent according to any one of claims 1 to 4, a metal material having a dry film of 0.05~ 0.2 g / ^{m 2} to the surface.   An environmentally-friendly precoated steel sheet in which an upper film not containing chromium is further formed on the surface of the metal material according to claim 5.