KR20170068551A - Surface treatment agent for zinc-plated steel sheets - Google Patents

Abstract

Provided is a surface treatment agent for a zinc-based plated steel sheet which satisfies both of corrosion resistance, adhesion to a top coat, weathering resistance and adhesion to a structural adhesive.
Based surface treatment agent for a zinc-based plated steel sheet comprising a zirconium carbonate compound, a specific acrylic resin, a vanadium compound, a phosphorus compound and a cobalt compound.

Description

{SURFACE TREATMENT AGENT FOR ZINC-PLATED STEEL SHEETS}

The present invention relates to the treatment of the surface of zinc plated steel sheet which is excellent in corrosion resistance, adhesion to a top coat, weathering resistance and adhesion to a structural adhesive.

The galvanized steel sheet is applied to a wide range of applications such as building materials, automobiles, and household appliances.

In general, as a technique of forming a coating film on the surface of a zinc-based plated steel sheet by a surface treatment agent and imparting corrosion resistance and the like, there are a method of performing chromate treatment with a treatment liquid containing chromic acid, dichromic acid, or a salt thereof as a main component, A method of performing the treatment, a method of performing the inorganic metal film treatment, a method of performing the organic resin film treatment, and the like are known and put to practical use.

As a technique mainly using an inorganic component, Patent Document 1 discloses a metal surface treatment agent containing a vanadium compound and a metal compound containing at least one metal selected from zirconium, titanium, molybdenum, tungsten, manganese and cerium . Patent Document 2 discloses a composite coated zinc-containing plated steel material using a treatment liquid containing a basic zirconium compound, a vanadyl-containing compound, a phosphoric acid compound, a cobalt compound, an organic acid and water.

As a technique mainly using an organic resin film treatment, Patent Document 3 discloses a surface treatment agent for a metal material comprising an alkali metal silicate in an anionic water-dispersible resin, and Patent Document 4 discloses a surface treatment agent for a metal material in which zirconium carbonate, tetravalent vanadium compound, , And an anionic water-dispersible acrylic resin.

Patent Document 5 discloses a technique for forming a film on a zinc-aluminum alloy plated steel sheet excellent in corrosion resistance by coating with a surface treatment agent to improve corrosion resistance and the like. In Patent Document 5, a zirconium compound, a vanadium compound Patent Document 6 discloses a zinc-aluminum alloy-plated steel sheet on which a coating composed of a zinc-aluminum alloy plated steel sheet is formed on a Zn-Al alloy plating, and a zinc-aluminum alloy plated steel sheet composed of an acrylic resin composed of a vanadium compound, A coated steel sheet is disclosed.

However, these techniques are not satisfactory in terms of the flat portion corrosion resistance, the process portion corrosion resistance, the adhesion to the top coat, and the black weatherability, and particularly the adhesion to the structural adhesive, and thus they have problems in practical use. Therefore, there is a strong demand for the development of a surface treatment agent for zinc plated steel sheet which can be satisfactorily satisfied in a wide range of applications.

Japanese Patent Application Laid-Open No. 2002-30460 WO2007 / 123276 WO2007 / 069783 WO2009 / 004684 Japanese Patent Application Laid-Open No. 2003-55777 Japanese Patent Application Laid-Open No. 2005-097733

An object of the present invention is to provide a surface treating agent for zinc-based galvanized steel sheet that satisfies both the problems of the prior art, and satisfies both the corrosion resistance, the adhesion to the top coat, the weathering resistance and the adhesion to the structural adhesive.

In order to achieve this object, the inventors of the present invention have further investigated the use of a water-based surface treatment agent containing a zirconium carbonate compound, a specific acrylic resin, a vanadium compound, a phosphorus compound and a cobalt compound, And that the above object can be achieved by using a heat treated surface treated steel sheet, and have accomplished the present invention.

That is, the present invention provides the following.

(1) copolymerizing a monomer component comprising a zirconium carbonate compound (A) and at least styrene (b1), (meth) acrylic acid (b2), (meth) acrylic acid alkyl ester (b3) and acrylonitrile Wherein the amount of the acrylonitrile (b4) is 20 to 38% by mass based on the solid content of the entire monomer component of the resin, and the water-soluble resin having a glass transition temperature of -12 to 15 占 폚 And a water-based emulsion resin (B) which is a water-based emulsion resin, a 2 to 4-valent vanadium compound (C), a phosphorus compound (D), a cobalt compound Treatment agent for galvanized steel sheet.

(2) the blending amount of the acrylic resin (B) is 20 to 60 mass% with respect to the total solid content of the surface treating agent,

(V) / (Zr)] of the mass when the vanadium compound (C) is converted to V and the mass when the zirconium carbonate compound (A) is converted into Zr is 0.07 to 0.69,

(P) / (Zr)] of the mass of the phosphorus compound (D) converted to P and the mass of the zirconium carbonate compound (A) converted to Zr is 0.04 to 0.58,

(1) wherein the mass ratio of the cobalt compound (E) converted to Co and the mass ratio of the mass when the zirconium carbonate compound (A) is converted to Zr is 0.005 to 0.08, A surface treatment agent for zinc plated steel sheet according to claim 1,

(3) the amount of each monomer component in the acrylic resin (B) is from 15 to 25 mass% of styrene (b1) and from 15 to 25 mass% of (meth) acrylic acid (b2) based on the solid content of the entire monomer component of the resin. (1) or (2), wherein the (meth) acrylic acid alkyl ester (b3) is contained in an amount of 1 to 10 mass% and the (meth) acrylic acid alkyl ester (b3) is 40 to 58 mass%.

(4) The zinc-based plated steel sheet according to any one of the above items (1) to (4), wherein the zinc-based plated layer of the zinc-based plated steel sheet contains, in addition to zinc and inevitable impurities, 60 mass% or less of Al, 10 mass% or less of Mg, and 2 mass% (1) to (3), wherein the surface treatment agent for zinc-based plated steel sheet according to any one of (1) to (3)

(5) The surface treatment agent according to the above (1) to (4), wherein at least a part of the phosphorus compound (D) is an inorganic phosphoric acid and / or a salt thereof.

The present invention is a surface treatment agent for a zinc-based plated steel sheet that satisfies both of corrosion resistance, adhesion to a top coat, weathering resistance and adhesion to a structural adhesive.

Hereinafter, the present invention will be described in detail.

The aqueous surface treatment agent used in the present invention is a zirconium carbonate compound (A) as a raw material. The carbonate zirconium compound (A) is inferior in carbonate ion when the film is formed, and the zirconium bonds to each other through oxygen to increase the molecular weight, thereby increasing the barrier property of the film. In addition, the zirconium carbonate compound can cause a crosslinking reaction with the acrylic resin (B) to enhance the barrier property of the coating film. The kind of the zirconium carbonate compound (A) is not particularly limited, and examples thereof include zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate and sodium zirconium carbonate, and at least one of them can be used. Among them, zirconium carbonate and zirconium carbonate are preferred because of their excellent corrosion resistance.

As the aqueous surface treatment agent used in the present invention, an acrylic resin (B) is used as a raw material. It is considered that the acrylic resin has high molecular weight by regular arrangement with the above-mentioned zirconium carbonate (A), and imparts the characteristics of the organic coating to the poorly soluble zirconium coating. Particularly, the film formed by high molecular weight by regular arrangement is imparted with the properties derived from the monomer component constituting the acrylic resin, and it is possible to exhibit the performance required for adhesion with the structural adhesive. The content of the acrylic resin (B) is preferably 20 to 60 mass% with respect to the total solid content of the surface treatment agent. More preferably from 20 to 40% by mass. If it is less than 20 mass%, the adhesion property is deteriorated, and when it exceeds 60 mass%, corrosion resistance is deteriorated.

The acrylic resin (B) is obtained by copolymerizing a monomer component containing at least styrene (b1), (meth) acrylic acid (b2), (meth) acrylic acid alkyl ester (b3) and acrylonitrile And the amount of the acrylonitrile (b4) is 20 to 38% by mass based on the solid content of the entire monomer component of the resin, and the water-soluble resin having a glass transition temperature of -12 to 15 占 폚, Emulsion resin. Here, the monomer component (composition) other than the acrylonitrile (b4) is preferably a mixture of 15 to 25 mass% of styrene (b1) and (meth) acrylic acid (b2) in the total mass of the monomer components (Meth) acrylic acid alkyl ester (b3) in an amount of 1 to 10 mass% and 40 to 58 mass%, respectively.

Styrene (b1) has an effect of enhancing corrosion resistance and adhesion, and therefore it is preferably contained in an amount of 15 to 25 mass%, and more preferably in a range of 17 to 23 mass%. When the content is less than 15 mass%, the corrosion resistance and the adhesion property are deteriorated. When the content is more than 25 mass%, the coating is hardened and the corrosion resistance of the processed portion is deteriorated.

The (meth) acrylic acid (b2) has an effect of improving the adhesion of the film to the steel sheet of the resin, and is preferably contained in an amount of 1 to 10 mass%, more preferably 2 to 6 mass%. When the content is less than 1% by mass, the adhesiveness is deteriorated. When the content exceeds 10% by mass, the corrosion resistance and water resistance are deteriorated.

The (meth) acrylic acid alkyl ester (b3) has an effect of improving the workability of the resin film, and is preferably contained in an amount of 40 to 58 mass%, and more preferably 40 to 55 mass%. When it is less than 40 mass%, the corrosion resistance of the processed portion is deteriorated, and when it exceeds 58 mass%, the corrosion resistance of the flat portion is decreased. (Meth) acrylic acid alkyl ester (b3) is not limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-methylhexyl acrylate and isomers thereof And at least one of them may be used. Above all, ethyl acrylate and butyl acrylate are preferred because of their excellent corrosion resistance.

Acrylonitrile (b4) has an effect of enhancing adhesion with a structural adhesive, and contains 20 to 38 mass%, preferably 20 to 35 mass%. When it is 20 mass% or more, adhesion can be improved. On the other hand, when it exceeds 38% by mass, the water resistance is lowered and the corrosion resistance is lowered.

The acrylic resin (B) has a calculated glass transition temperature of -12 to 15 占 폚. When the glass transition temperature is higher than -12 占 폚, the corrosion resistance can be improved. On the other hand, if it exceeds 15 ° C, the adhesion decreases. Further, the glass transition temperature is calculated by the following equation, where i is an integer of 1 or more, Wi is the mass fraction of the i-homopolymer, and Tgi is the Tg (K) of the i-homopolymer.

When the styrene (b1), the (meth) acrylic acid (b2), the (meth) acrylic acid alkyl ester (b3) and the acrylonitrile (b4) are copolymerized in an appropriate amount, the acrylic resin (B) It is also possible to use it as raw material monomer. Examples of such a vinyl group-containing monomer include, but are not limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (Meth) allyl ether, 2-dimethylaminoethyl acrylate, acrylamide, allyl alcohol, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, Vinyltrimethoxysilane, vinyltriethoxysilane, allyl glycidyl ether, glycidyl (meth) acrylate, 2- (1-aziridinyl) ethyl acrylate, iminol methacrylate, acryloylmorphol Folin, vinyl formate, vinyl acetate, Acid vinyl, vinyl acrylic, vinyl toluene, cinnamic acid nitrile, (meth) acryloxyethyl phosphate and bis- and the like (meth) acryloxyethyl phosphate, it can be used at least one kind of these. Of these, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, ethoxy-diethylene glycol acrylate and acrylamide are preferable from the viewpoint of excellent emulsion stability.

The polymerization method of the polymer used in the present invention is not particularly limited, and examples thereof include suspension polymerization, emulsion polymerization and solution polymerization. It is also possible to use a solvent and a polymerization initiator when copolymerizing. The polymerization initiator is not particularly limited, but a radical polymerization initiator such as an azo-based compound or a peroxide-based compound can be used, and it is preferable to use 0.1 to 10% by mass based on the total solid content of the resin. The reaction temperature is usually from room temperature to 200 ° C, preferably from 40 to 150 ° C, and the reaction time is from 30 minutes to 8 hours, preferably from 2 to 4 hours.

The aqueous surface treating agent used in the present invention is a raw material containing a vanadium compound (C) having a valence of 2 to 4. The vanadium compound has 2 to 5 valence vanadium compounds. The vanadium compound is preferentially eluted under the corrosive environment and inhibits the pH increase due to dissolution of the plating component, so that the corrosion resistance is improved. Any oxidation number of vanadium is equally effective, but since vanadium pentavalent has high solubility, it is necessary to use a vanadium compound having 2 to 4 valences.

These two to four valent vanadium compounds (C) have a mass ratio [(V) / (Zr)] of 0.07 to 0.69 when the zirconium carbonate compound (A) is converted to Zr and the vanadium compound (C) Is 0.14 to 0.56. When [(V) / (Zr)] is 0.07 or more, the corrosion resistance of the machined portion can be improved. On the other hand, when [(V) / (Zr)] exceeds 0.69, the top coatability is lowered, which is not preferable.

The kind of the 2 to 4-valent vanadium compound (C) is not particularly limited and examples thereof include vanadium pentoxide (V ₂ O ₅ ), metavanadic acid (HVO ₃ ), ammonium metavanadate, sodium metavanadate, vanadium trichloride (VOCl ₃ ), and the like, which are reduced by 2 to 4 reduction with a reducing agent, vanadium trioxide (V ₂ O ₃ ), vanadium dioxide (VO ₂ ), vanadium oxysulfate (VOSO ₄ ), vanadium oxyoxalate (COO) _2], (vanadium oxy-acetylacetonate _{[VO (OC (CH 3)} = CHCOCH 3)) 2], vanadium acetylacetonate _{[V (OC (CH 3)} = CHCOCH 3)) 3], phosphorus trichloride vanadium (VCl ₃ ), in vanadium molybdic acid {H _15-X [PV _{12- x} Mo _x O ₄₀ ] nH ₂ O (6 <x <12, n <30), vanadium sulfate (VSO ₄揃 8H ₂ O, a vanadium compound having an oxidation number of 4 to _{2 such} as vanadium dichloride (VCl ₂ ), vanadium oxide (VO), and the like.

The aqueous surface treatment agent used in the present invention contains phosphorus compound (D) as a raw material. The phosphorus compound (D) is considered to partially dissolve the zinc-aluminum-magnesium alloy plating film to form a phosphate. This phosphate is mainly formed as zinc phosphate to passivate the surface of the plated film, thereby improving the corrosion resistance and improving the adhesion. Particularly, at least a part of the phosphorus compound (D) is preferably an inorganic phosphoric acid and / or a salt thereof from the viewpoint of improving adhesion with a structural adhesive. Examples of the counter cation in the salt (including the salt described below) include, for example, an alkali metal, an alkaline earth metal, and ammonium.

The phosphorus compound (D) has a mass ratio [(P) / (Zr)] when the zirconium carbonate compound (A) is converted to Zr and the phosphorus compound (D) in terms of P is 0.04 to 0.58, preferably 0.07 to 0.29. When [(P) / (Zr)] is 0.04 or more, the corrosion resistance of the processed portion can be improved. On the other hand, when [(P) / (Zr)] is more than 0.58, it is not preferable because the black weathering is lowered.

The phosphorus compound (D) used in the present invention is, for example, an inorganic acid anion having an acid group and containing phosphorus, for example, orthophosphoric acid, metaphosphoric acid, condensed phosphoric acid, pyrophosphoric acid, , And salts thereof. Examples of the organic acid anion having an acid group containing phosphorus include 1-hydroxymethane-1,1-diphosphonic acid, Hydroxypropane-1,1-diphosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, 2-hydroxyphosphonoacetic acid, N, N ', N'-tetra (methylenephosphonic acid), di (methylenephosphonic acid), ethylenediamine-N, Ethylenetriamine-N, N, N ', N ", N" -penta (methylenephosphonic acid), 2-phosphonic acid butane-1,2,4-tricarboxylic acid, Include acid, phytic acid, such as an organic acid, the at least one hydrogen has glass and organic acid anion salts such as those of the organic acid.

The aqueous surface treatment agent used in the present invention contains a cobalt compound (E) as a raw material. Generally, the zinc-aluminum-magnesium alloy plating film exhibits a sacrificial effect of aluminum and magnesium under a corrosive environment, and therefore, a black phenomenon occurs in which zinc in the plating film is oxidized in an oxygen deficiency state. This is a phenomenon which is likely to occur in the easily soluble part of the plated film, and it is considered that the cobalt compound is substituted and precipitated at this part, thereby giving better black weathering.

The cobalt compound (E) has a mass ratio [(Co) / (Zr)] of 0.005 to 0.08, preferably 0.009 to 0.038, when the zirconium carbonate compound (A) is converted to Zr and the cobalt compound (E) When [(Co) / (Zr)] is 0.005 or more, it is possible to improve the corrosion resistance of the processed portion and the black weathering. On the other hand, when [(Co) / (Zr)] exceeds 0.08, the corrosion resistance is lowered. The kind of the cobalt compound (E) is not particularly limited, and examples thereof include cobalt sulfate, cobalt nitrate, and cobalt carbonate.

The pH of the aqueous surface treatment agent used in the present invention is 8 to 11. And more preferably 8.5 to 10. The method of measuring the pH is not limited. For example, it is possible to measure the pH at a measuring temperature of 25 DEG C (HM-30R) manufactured by Dow Corning Toray Co., Ltd. When the pH is less than 8, the zirconium carbonate compound (A) can not be stably dissolved and the corrosion resistance is lowered. On the other hand, when it exceeds 11, the plated film is severely dissolved and the corrosion resistance is lowered. In addition, if the pH is within the above range, it also contributes to the stability of the agent. The pH adjusting agent is not particularly limited, and examples thereof include ammonia, guanidine carbonate, carbonic acid, acetic acid, hydrofluoric acid and the like.

Further, the aqueous surface treatment agent used in the present invention can be added with the lubricant (F) for the purpose of improving scratch resistance. The blending amount of the lubricant (F) is preferably 1 to 8% by mass with respect to the total solid content of the surface treating agent. When the blending amount of the lubricant (F) is less than 1% by mass, improvement in scratch resistance is not obtained. On the other hand, if it exceeds 8% by mass, the coating adhesion may deteriorate.

It is preferable that the lubricant (F) has a mass average particle diameter of 0.1 to 5.0 mu m. The method of measuring the weight-average particle diameter is not limited, but it can be measured by, for example, a laser diffraction scattering type particle size distribution measuring device MICROTRAC HRA-X100 manufactured by Nikkiso Co., Ltd. When the mass average particle diameter is less than 0.1 탆, aggregation is likely to occur and stability is deteriorated. On the other hand, when the mass average particle diameter exceeds 5.0 탆, dispersion stability is lowered, which is not preferable.

The water-based surface treatment agent to be used in the present invention may be a surfactant or thickening agent called wettability improving agent for obtaining a uniform coating film, a conductive substance for improving weldability, a coloring pigment or quenching material for improving designability, a solvent for improving film formability, etc. May be added as long as the effect of the present invention is not impaired.

The water-based surface treatment agent is obtained by mixing the above components in water such as deionized water, distilled water and the like. The solid content ratio of the aqueous surface treatment liquid may be appropriately selected. Further, a water-soluble solvent, a surfactant, a defoaming agent, a leveling agent, an antibacterial / antiseptic agent, etc. may be added to the water-based surface treatment agent, if necessary, in an alcohol, ketone or cellosolve system. By adding them, the dryness, application appearance, workability and designability of the surface treatment agent are improved. However, it is important that they are added to such an extent as not to impair the quality obtained in the present invention, and the added amount is less than 5% by mass based on the total solid content of the aqueous surface treatment liquid.

Next, the treatment method of the water surface treatment agent of the present invention will be described.

In the present invention, it is preferable to have a surface-treated coating film having a Zr adhering amount per one surface of 8 to 700 mg / m 2 by applying an aqueous surface treatment agent to the surface of the zinc-base plated steel sheet and heating and drying it. When the amount of Zr deposited is 8 mg / m &lt; 2 &gt; or more, corrosion resistance can be improved. On the other hand, when it exceeds 700 mg / m 2, the performance such as corrosion resistance is saturated. More preferably 50 to 350 mg / m 2.

Examples of the method of applying the aqueous surface treatment agent include a roll coating method, a bar coating method, a dipping method and a spray coating method, and an optimum method is suitably selected according to the shape to be treated and the like. More specifically, for example, the roll coating method, the bar coating method, or the spray coating method can be selected if the shape is in a sheet form. The spray coating method is a method of spraying an aqueous surface treatment agent and spraying roll drawing or gas at a high pressure to adjust the application amount. In the case of a molded product, a method of immersing in a surface treatment solution and extracting it, and in some cases, blowing an extra aqueous surface treatment agent into the compressed air to adjust the application amount is selected.

The heating temperature (maximum reached temperature, PMT) when the aqueous surface treatment agent is heated and dried is usually 60 to 200 캜, and more preferably 80 to 180 캜. If the heating temperature is 60 占 폚 or higher, moisture as a main solvent does not remain in the film. Further, if the heating temperature is 200 占 폚 or lower, decomposition of the resin does not occur and problems such as deterioration in corrosion resistance are not caused. The heating time is appropriately selected in accordance with the shape to be used and the like. From the viewpoint of productivity and the like, 0.1 to 60 seconds is preferable, and 1 to 30 seconds is more preferable.

The zinc plated steel sheet formed with the surface treatment agent by the surface treatment agent of the present invention satisfies both the corrosion resistance, the adhesion to the top coat, the weathering resistance and the adhesion to the structural adhesive. This reason is presumed as follows, but the present invention is not limited to such a guess. The coating formed using the aqueous metal surface treatment agent used in the present invention forms a barrier coating with a zirconium carbonate compound and an anionic acrylic resin. The zirconium carbonate compound volatilizes carbonic acid during the drying process, and the remaining zirconium is polymerized to form a soluble film. In this process, it is presumed that one part (-Zr-OH group) of zirconium forms a Zr-O-M bond (M: zinc-based plating) with the metal surface, so that the adhesion with plating is excellent and a remarkable barrier effect is exerted. Further, it is considered that the zirconium and the anionic acrylic resin are made to have a high molecular weight by regular arrangement, giving the zirconium film having poor resistance to the general characteristics of the organic film.

Particularly, the film formed by high molecular weight by regular arrangement is imparted with the properties derived from the monomer component constituting the acrylic resin, and in particular, it is possible to exhibit the performance necessary for adhesion with the structural adhesive. On the other hand, the vanadium compound is considered to be an inhibitor component that elutes and works under a corrosive environment. That is, it has an effect of eluting under a corrosive environment and delaying the pH rise of the plating film. In this process, it is possible to maintain good corrosion resistance over a long period by the effect of the sacrificial system in which zinc plating forms an oxide film. Further, the phosphorus compound etches the metal when it comes into contact with the metal surface to form an insoluble metal salt with the dissolved metal. Or corrosion of the metal occurs, it is considered that metal ions are supplemented to form a metal salt, thereby further suppressing corrosion. Further, the cobalt compound is present as ions in the treatment liquid, and when it comes into contact with the metal, the cobalt compound is substituted and precipitated on the metal surface. Although the blackening phenomenon due to the oxygen deficiency is not clear, it is possible to exhibit excellent blackening by the modification of the metal surface by the cobalt compound.

The adhesive that exhibits good adhesion with the film formed by the surface treatment agent of the present invention is not particularly limited and may be, for example, a silicone type (including acrylic modified or epoxy modified), epoxy type, acrylic resin type, phenol type, Vinyl acetate type, cyanoacrylate type, and styrene butadiene rubber type. The material to be adhered to the zinc plated steel sheet formed with the various adhesives through the adhesive is not particularly limited and may be, for example, a steel sheet, a mortar, a float glass, a ceramic tile and a MDF ) And the like.

The zinc plated steel sheet to which the surface treatment agent is applied is not particularly limited and may be a steel sheet formed with a zinc-containing plated coating by a known plating method or the like. Examples of the plating method include hot-dip plating, electroplating, and the like. As zinc-based coated steel sheets, there are zinc-plated galvanized steel sheets, electro-galvanized-nickel alloy coated steel sheets, hot-dip galvanized steel sheets, hot-dip galvanized- Alloy-coated steel sheets, alloyed hot-dip coated steel sheets, and the like. The plating adhesion amount is not particularly limited and may be determined depending on the use environment and the application. Here, the zinc-based plated layer of the zinc-based plated steel sheet may contain, in addition to zinc and inevitable impurities, at least one of 60 mass% or less of Al, 10 mass% or less of Mg, and 2 mass% or less of Si It is acceptable. The inevitable impurities are impurities which are inevitably incorporated in the manufacturing process or the like. For example, Pb, Cd, Sb, Cu, Fe, Ti, Ni, B, Zr, Hf, Sc, Sn, Cr, Mn, Mo, P, Nb, V, Bi, and also Group III elements such as La, Ce and Y. The total of these inevitable impurity elements is preferably about 0.5 mass% or less.

Example

EXAMPLES The present invention will be described below with reference to examples and comparative examples. However, the present examples are merely illustrative and do not limit the present invention. The evaluation methods for the test pieces produced in Examples and Comparative Examples are as follows.

1. Material

The plated steel used is described below.

M1: Melted Zn plating (plating amount: 90 g / m 2)

M2: Melting 11% Al-3% Mg-0.2% Si-Zn plating (plating amount 90 g / m2)

M3: Electric Zn plating (plating adhesion amount 20g / ㎡)

M4: Electric 11% Ni-Zn plating (plating adhesion amount 20g / ㎡)

M5: Melting 55% Al-1.6% Si-Zn plating (plating coverage 90 g / m2)

2. Treatment agent

(1) Processing agent component

The used zirconium carbonate compound (A) and other zirconium compounds are described below.

A1: Zirconium carbonate potassium

A2: Zirconium carbonate ammonium

A3: Ammonium zirconium fluoride

(B1), (meth) acrylic acid (b2), (meth) acrylic acid alkyl ester (b3), acrylonitrile (b4) and unsaturated monomer (b5) copolymerizable with these monomers, Using the ratios shown in Table 2, the polymers B1 to B38 shown in Table 3 were obtained. The Tg at the right end of Table 2 is the glass transition temperature of each polymer. Also, the unsaturated monomer (b5) was appropriately selected from 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, ethoxy-diethylene glycol acrylate and acrylamide.

[Table 1]

[Table 2]

The used 2- to 4-valent vanadium compound (C) is described below.

C1: Vanadium acetylacetonate

C2: vanadium oxyoxalate

The phosphorus compound (D) used is described below.

D1: phosphoric acid

D2: 1-Hydroxyethane-1,1-diphosphonic acid

The used cobalt compound (E) is described below.

E1: Cobalt carbonate

E2: Cobalt nitrate

&Lt; Preparation of treatment agent &

Tables 3A and 3B show the compositions of the treatment solutions of Examples and Comparative Examples. The treatment liquid was prepared so that the solid concentration was 15% by mass by sequentially adding each component while stirring the solution to a predetermined amount of deionized water using a propeller stirrer. As pH adjusters, carbonic acid and ammonia were used. Further, when D1 and D2 were used in combination as the phosphorus compound (D), the mass ratio of D1 to D2 = 85: 15 was obtained in terms of P in the treating solution.

3. Processing method

(1) degreasing

The material was degreased with an alkali degreasing agent Fine Cleaner E6406 (20 g / L bath, 60 캜, 10 seconds spray, spray pressure 50 제) manufactured by Nihon Parkerizing Co., Ltd., and spray-rinsing was carried out for 10 seconds.

(2) Application and drying of the treatment liquid

The treatment liquid was applied to a bar coater and dried using a hot air circulation type oven. And the concentration of the treatment liquid and the number of bar coaters were appropriately selected so as to achieve the target Zr deposition amount. The amount of Zr adhered was measured by a fluorescent X-ray analyzer ZSX-PrimusII (manufactured by Rigaku Kabushiki Kaisha).

Evaluation items and test methods are shown below. The evaluation results are shown in Tables 4A and 4B.

ㆍ Corrosion resistance

The test piece subjected to the Erickson process with a flat plate and a height of 7 mm was subjected to a salt water spray test according to JIS Z2371 for a predetermined time. The corrosion resistance was judged by the area ratio of white rust after the salt spray test.

Evaluation criteria of corrosion resistance are shown below.

Flat plate test piece (after 240 hours of salt spray test)

◎: white rust 0%

○: more than 0% and less than 5%

○ -: more than 5% and less than 15%

△: more than 15% and less than 30%

×: more than 30% of white rye

Erickson processing specimens (after 72 hours of salt spray testing)

◎: white rust 0%

○: more than 0% and less than 15%

○ -: more than 15% and less than 30%

△: more than 30% and less than 50%

×: more than 50% of white rust

ㆍ Darkness Modification

The appearance of the test piece after standing for 144 hours under an atmosphere of 70 캜 RH 85% was visually observed using a constant temperature and humidity testing machine.

The evaluation criteria for the resistance to blackening are shown below.

◎: No change at all

○: Almost no change

○ -: A slight discoloration appears at the end

?: Slight discoloration was observed

X: Apparent discoloration is observed

ㆍ Coating adhesion

The test piece was coated with Amilac 1000 white (manufactured by Kansai Paint Co., Ltd.) using a bar coater and dried by heating at 125 캜 for 20 minutes to obtain a dry film thickness of 20 탆. Subsequently, the sample was immersed in boiling water for 30 minutes, taken out, and allowed to stand for 24 hours. Thereafter, a cutter knife was used to form a checkerboard pattern of 1 mm and 100 chambers, and the remaining number of coat films was determined by a tape peel test.

Evaluation criteria of paint adhesion are shown below.

◎: Remaining number 100

○: Remaining number 98 or more and less than 100

?: Remaining number 50 or more and less than 98

X: Less than 50 residues

&Lt; Stability of treating agent &

The treating agent was allowed to stand in a thermostat at a temperature of 40 占 폚 for 3 months, and the appearance of the liquid was observed.

Evaluation criteria are shown below.

◎: Almost no change

○: Slight cloudiness

△: with sediment

X: Gelation, large amount of precipitation

ㆍ Adhesiveness evaluation

The adhesiveness between the zinc plated steel sheets or between the zinc plated steel sheet and the other materials was evaluated using the various evaluation methods 1 to 4 by using various adhesives. The adhesive and the other material test piece used in Evaluation Method 2 are shown below.

A: Epoxy type (Konishi, E2300J)

Other material specimen: Mortar specimen

B: Acrylic type (Hard Rock 8 made by Denki Kagaku Kogyo Co., Ltd.)

Other material specimen: Mortar specimen

C: Silicone type (Dow Corning Toray, PV8303)

Other material specimen: Float glass

D: Silicone (CEMEDINE, PM210)

Other material test specimens: Ceramic tile, float glass

E: Silicone (Cemetamine, Super X No. 8008)

Other material specimen: Float glass

F: Phenolic (cemetamine, 110)

Other material specimen: None

G: Urethane series (cemedane, UM700)

Raw material test piece: MDF (Medium Density Fiberboard)

H: Vinyl acetate type (Konishi, CH18)

Raw material test piece: MDF (Medium Density Fiberboard)

I: chloroprene rubber (cemedane, 575F)

Raw material test piece: MDF (Medium Density Fiberboard)

Evaluation method 1: A lap shear test specimen (25 ± 0.5 mm × 12.5 ± 0.5 mm) made of two test pieces (25 ± 0.5 mm × 100 ± × 1.6 mm thickness) with an adhesive was prepared and cured for a predetermined time , And the primary adhesion property was evaluated.

Evaluation method 2: The test piece (25 ± 0.5 mm × 100 ± 0.5 mm × 1.6 mm thickness) and the other material test piece (25 ± 0.5 mm × 100 ± 0.5 mm × arbitrary thickness) ± 0.5 mm) was prepared and cured for a predetermined time, after which the primary adhesion property was evaluated.

Evaluation method 3: After curing the test specimen of the evaluation method 1, the secondary adhesion property was evaluated at a temperature of 50 DEG C and 85% after a predetermined time.

Evaluation method 4: After curing the test specimen of evaluation method 1, the secondary adhesion property was evaluated at 85 캜 and 85% after a predetermined time elapsed.

Adhesion was evaluated by tensile shear load and cohesive failure rate. The tensile shear load was measured at a tensile rate of 100 mm / min and a room temperature of 25 ° C and was evaluated by the tensile shear load ratio (tensile shear load of the test material / tensile shear load of the untreated material) with the untreated test pieces. Evaluation criteria of tensile shear load are shown below.

?: 1.1 or more

○: 1.0 seconds to less than 1.1

?: 1.0 (equivalent to untreated test piece)

×: less than 1.0

Further, the residual area (cohesive failure rate) of the adhesive on the zinc plated steel sheet side after the tensile shear test was evaluated in comparison with the untreated material. The evaluation criteria of the cohesive failure rate are shown below.

◎: Residual area of adhesive is apparently increased

○: Residual area of adhesive increased

Δ: Equivalent to untreated material

X: The remaining area of the adhesive decreased

[Table 3A]

[Table 3B]

[Table 4A]

[Table 4B]

Claims (5)

The zirconium carbonate compound (A)
A resin obtained by copolymerizing at least a monomer component comprising styrene (b1), (meth) acrylic acid (b2), (meth) acrylic acid alkyl ester (b3) and acrylonitrile (b4), and acrylonitrile (b4) is 20 to 38% by mass based on the solid mass of the total monomer component of the resin, and the water-soluble resin having a glass transition temperature of -12 to 15 占 폚 and the acrylic resin B)
A vanadium compound (C) having 2 to 4 valences,
Phosphorus compound (D)
The cobalt compound (E)
Water, and having a pH of from 8 to 11, and a surface treatment agent for zinc plated steel sheet. The method according to claim 1,
The blending amount of the acrylic resin (B) is 20 to 60 mass% with respect to the total solid content of the surface treatment agent,
(V) / (Zr)] of the mass when the vanadium compound (C) is converted to V and the mass when the zirconium carbonate compound (A) is converted into Zr is 0.07 to 0.69,
(P) / (Zr)] of the mass of the phosphorus compound (D) converted to P and the mass of the zirconium carbonate compound (A) converted to Zr is 0.04 to 0.58,
(Co) / (Zr)] of the mass of the cobalt compound (E) converted to Co and the mass of the zirconium carbonate compound (A) converted to Zr is 0.005 to 0.08, Surface treatment agent for steel sheet. 3. The method according to claim 1 or 2,
Wherein the amount of each monomer component of the acrylic resin (B) is 15 to 25 mass% of styrene (b1), 1 to 10 mass% of (meth) acrylic acid (b2) based on the solid content of the entire monomer components of the resin, % By mass of a (meth) acrylic acid alkyl ester (b3), and 40 to 58% by mass of a (meth) acrylic acid alkyl ester (b3). 4. The method according to any one of claims 1 to 3,
Wherein the zinc-based plated layer of the zinc-based plated steel sheet contains, in addition to zinc and inevitable impurities, at least 60 mass% Al, 10 mass% or less Mg, and 2 mass% or less Si, Surface treatment agent for zinc plated steel sheet. 5. The method according to any one of claims 1 to 4,
Wherein at least a part of the phosphorus compound (D) is an inorganic phosphoric acid and / or a salt thereof.