TWI444504B - Surface-treating agent for galvanized steel plate - Google Patents

Description

Surface treatment agent for galvanized steel sheets

The present invention relates to a surface treatment agent for a galvanized steel sheet, a surface treatment method using the surface treatment agent for the galvanized steel sheet, and a surface-treated galvanized steel sheet.

At present, galvanization is often performed on the surface of a steel sheet from the viewpoint of ensuring corrosion resistance of the steel sheet. Further, in order to further improve the corrosion resistance or improve the coating property, an alloyed galvanized steel sheet to which various metals are added is used.

In particular, in industrial areas and other places that are affected by acid rain or soot, or in areas such as coastal areas that are affected by sea salt blowing particles, it is likely to cause extremely severe environmental corrosion of steel sheets, so it is expected to develop under the above circumstances. A galvanized steel sheet having more excellent corrosion resistance can also be used. In response to the above demand, galvanized steel sheets having improved corrosion resistance such as Zn-5% Al alloy steel sheets, hot-dip galvanized-Al-Mg alloy steel sheets, and hot-dip galvanized-55% Al alloy steel sheets have been proposed.

However, even in the above various galvanized steel sheets, the corrosion resistance (white rust resistance) may be insufficient, and when used as a coated steel sheet, the adhesion to the coating may be insufficient. In the solution, a treatment containing hexavalent chromium called temporary rust-resistant chromate treatment is performed on the surface of the galvanized steel sheet. Further, in the production line (CGL: Continuous Galvanizing Line) using the temporary rust-resistant chromate-treated hot-dip galvanized steel sheet, the following method is mainly carried out: chromic acid containing chromic acid (hexavalent chromium) as a main component The salt treatment liquid is sprayed on the steel plate by a sprayer or a shower, and then the coating amount is adjusted by a roller or an air diaphragm, and then dried by an oven or the like (referred to as a spray squeezing roller: spray wringer, shower squeezing roller) :shower wringer).

In the chromate treatment, although the surface treatment film is a film, it is excellent in corrosion resistance. However, these films have a problem of containing a large amount of harmful hexavalent chromium. In particular, the awareness of environmental protection issues has recently risen, and there is a tendency to abolish chromate treatment. In short, it is currently expected to be able to be converted to a chromium-free surface treatment that does not use harmful hexavalent chromium, even trivalent chromium.

In the above case, many research improvements have been made in the surface treatment method in which hexavalent chromium is not used. For example, Patent Document 1 discloses a zinc-based coated steel obtained by coating and drying a composition containing an aqueous resin, water, or sulfide ions. Patent Document 2 discloses a galvanized steel sheet coated with a water-dispersible metal surface treatment composition containing a specific combination of a compound and a resin emulsion. Patent Document 3 discloses a metal surface treatment material in which a film is formed using a water-based treatment agent containing a specific aqueous dispersion resin, cerium particles, and an organic inhibitor. Further, Patent Document 4 discloses a surface-treated metal sheet obtained by treating a metal material obtained by using a surface treatment composition containing a nonionic aqueous resin dispersion, hydrolyzable titanium, an organic phosphoric acid compound, and a vanadium compound. Patent Document 5 discloses a water-dispersed rust-preventing paint composition containing an ionic polymer resin, a water-soluble zirconium reactive with a carboxyl group, and/or a water-soluble titanium compound. Further, Patent Document 6 discloses surface treatment of a metal material obtained by using a metal surface treatment composition containing a hydrolyzable titanium, an organic phosphoric acid compound, a nonionic aqueous resin dispersion, a vanadium compound, and a zirconium compound. Metal plate.

In the above Patent Documents 1 to 6, a method of directly coating a surface of a galvanized layer with an organic film (resin film) containing no chromium is proposed.

On the other hand, Patent Document 7 discloses a metal plate having a film containing titanium and/or zircon, a phosphoric acid compound, and a ruthenium compound. Patent Document 8 discloses a galvanized steel sheet obtained by surface treatment using a treatment agent containing a water-soluble phosphate compound, a chelating agent, and a corrosion inhibitor. Further, Patent Document 9 discloses a surface-treated metal material having a film formed of a metal surface treatment agent containing a metal compound such as a vanadium compound or a zirconium compound. Further, Patent Document 10 discloses a steel sheet having a film composed of tetravalent vanadium, Si, and a phosphoric acid compound.

In the above Patent Documents 7 to 10, a metal material coated with a film containing no chromium as an inorganic component is disclosed. In addition, there are reports in these technologies for improving corrosion resistance by using water-based resins.

However, the conventional techniques of the above Patent Documents 1 to 10, in particular, the method of coating with an organic film, the adhesion of the organic film to the galvanized layer is still insufficient, and appears when it is treated as a coating substrate. The interface between the organic film and the plating layer is easily peeled off.

Furthermore, it is also necessary to ensure the weldability of the galvanized steel sheet. In addition, from the viewpoint of application of a galvanized steel sheet to home electric appliances and the like, it is also necessary to exhibit grounding properties. In short, the above galvanized steel sheet requires not only corrosion resistance but also grounding resistance and heat resistance.

However, in the galvanized steel sheet forming the resin film up to now, in order to obtain corrosion resistance, it is often necessary to set the amount of the film of the resin film to 1 g/m ² or more. Therefore, when the amount of the film is increased in order to obtain the corrosion resistance, there is a problem that the grounding property cannot be obtained. Further, in the case of the resin film, it is decomposed in a high-temperature environment, and the heat resistance is insufficient in either case.

Based on the above background, a steel sheet coated with a chromium-free film in which an inorganic component is mainly used instead of an organic component has been proposed. For example, Patent Document 11 discloses a steel sheet having a film obtained by using a composition containing phosphoric acid, titanium, zirconium or a decane coupling agent composed of four or more fluorine atoms. Further, Patent Document 12 discloses a steel sheet having a film obtained by using a treatment agent containing an amine group-containing decane coupling agent, a glycidyl group-containing decane coupling agent, titanium hydrofluoric acid or the like. Further, Patent Document 13 discloses a steel sheet having a film composed of a cerium sol binder, a phosphate ion, and a fluoride ion.

However, the steel sheets described in the above-mentioned Patent Documents 11 to 13 have good corrosion resistance and heat resistance. However, since a film having a large amount of acid components is formed, there is a problem of grounding properties and adhesion.

In addition, when the surface is beautiful hot-dip galvanizing, in these techniques, a film having a large amount of inorganic components is formed, fine cracks are formed on the film, the appearance of the film is whitened (whitening), and rainbow color is also seen. The problem of interference color. In particular, when whitening occurs, it may cause misunderstanding that white rust is formed on the galvanized surface, and there is a problem that the commercial value is lowered.

In addition, when galvanized steel sheets are preserved, water droplets are often generated on the surface of the steel sheet due to condensation. When the water droplets are dry, the water droplets may remain, and the problem that the commercial value of the steel sheet is lowered is caused, and the above problems are not solved in the prior art.

Furthermore, the temporary anti-rust chromate treatment as described above is generally carried out by spraying a chromate treatment liquid onto a steel plate by a spray or a shower, and then adjusting the coating amount by a roller or an air brake. Then, it is dried by an oven or the like. This surface treatment method is very simple and highly productive.

However, in the conventional technique of using chromium which has not been proposed so far, the treatment agent used may be water-based, and the active ingredient concentration (or dry solid content) of the composition is not more than 20 to 30% by mass. That is, in order to obtain a coating amount of 1 g/m ² (about 1 μm) by coating and drying it, a coating amount of the treatment liquid required is 4 to 5 g/m ² , which is limited by roll coating in order to control it. The tendency of the treatment method of the method (particularly, a method of applying a liquid by rotating the roller in a direction opposite to the direction of the thread by a method called a reverse roll coating method). Therefore, it is impossible to use the conventional manufacturing equipment, and it is necessary to invest in new equipment for the galvanizing production line (CGL, EGL). Further, at the time of reverse roll coating, the roll at the edge portion of the steel sheet at the time of coating is ground, resulting in occurrence of a thread (streak) flaw corresponding to the width of the sheet at the roll. The flaw affects the appearance of the coating, so it has to be produced in the order of the wider plate width to the narrower plate width, resulting in a new problem of sacrificing productivity in the continuous production process.

As described above, the surface-treated steel sheet instead of the chromate film cannot be obtained by any method. Therefore, it is strongly desired to develop a film which can comprehensively satisfy the corrosion resistance, appearance, grounding property, condensation resistance, and coating property of the film. (Paint film adhesion) and other characteristics, and can also be applied to the surface treatment agent of the conventional processing equipment.

Patent Document 1: Japanese Patent Publication No. 8-67834

Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 9-221595

Patent Document 3: JP-A-2002-241956

Patent Document 4: JP-A-2004-238638

Patent Document 5: JP-A-2005-15514

Patent Document 6: JP-A-2006-009121

Patent Document 7: JP-A-2004-2950

Patent Document 8: JP-A-2002-155375

Patent Document 9: JP-A-2002-30460

Patent Document 10: JP-A-2005-48199

Patent Document 11: JP-A-2006-213958

Patent Document 12: JP-A-2007-51365

Patent Document 13: JP-A-2007-177314

Accordingly, an object of the present invention is to provide a surface treatment agent for a galvanized steel sheet which can obtain a surface-treated galvanized steel sheet excellent in corrosion resistance, corrosion resistance after alkali degreasing, and the like, and particularly, the corrosion resistance of the formed film. The balance between the properties, the appearance, and the grounding property is good, and the condensation resistance and the coating property (coating film adhesion) also show excellent characteristics of balance. Further, another object of the present invention is to provide a surface-treated galvanized steel sheet which can be produced by a conventionally used processing method (a showering roll or a spray nip roll) in a manufacturing apparatus for a galvanized steel sheet.

The inventors of the present invention have diligently studied in order to solve the above problems, and as a result, have found that the above problems can be solved by using a compound having a predetermined functional group containing a halogen atom, a treatment agent containing ammonium zirconium carbonate, an organic phosphonic acid or the like, and the present problem can be solved. invention.

That is, the present invention provides the following (1) to (9).

(1) A surface treatment agent for a galvanized steel sheet, comprising:

Ammonium zirconium carbonate (A); the compound (B) having two or more in one molecule is represented by -SiR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ are each independently, and represent a carbon number a functional group (a) of an alkyl group, an alkoxy group or a hydroxyl group of 1 to 4, and a molecular weight (average molecular weight/number of functional groups) of 1 unit of the functional group (a) is in the range of 100 to 5,000; The organic phosphonic acid (C) represented by the metal compound (D) is selected from the group consisting of Zr, Ti, Co, Fe, V, Ce, Mo, Mn, Mg, Al, Ni, Ca, W, Nb, Cr. And at least one or more metal elements of the group consisting of Zn; and water; and having a pH of 6 to 11;

(2) The surface treatment agent for galvanized steel sheets according to (1), wherein the mass of Zr in the ammonium zirconium carbonate (A) is converted into ZrO ₂ and the Si in the compound (B) is converted into SiO ₂ The mass ratio (A/B) of the mass is 0.01 to 6.0; the mass ratio (C/B) of the mass of the organic phosphonic acid (C) to the mass of Si in the compound (B) converted to SiO ₂ is 0.01. ～5.0; The mass ratio (D/B) of the mass of the metal element in the metal compound (D) to the mass of Si in the compound (B) in terms of SiO ₂ is 0.01 to 4.0.

(3) A surface treatment agent for a galvanized steel sheet according to (1) or (2), wherein the compound (B) is a decane coupling agent having a reactive functional group (b1), and has a reactive functional group ( B1) The compound of the functional group (b2) of the reaction is reacted, and one of the reactive functional group (b1) and the functional group (b2) is an amino group or an epoxy group.

(4) A surface treatment agent for a galvanized steel sheet according to any one of (1) to (3), further comprising a metal alkoxide (E); the metal alkoxide (E) comprising a group selected from B and Nb At least one metal element of the group consisting of Si, Ta, Ti, V, W, and Zr.

(5) A surface treatment agent for a galvanized steel sheet according to (4), wherein the mass of the compound (B) in terms of Si in terms of SiO ₂ and the mass of the metal element contained in the metal alkoxide (E) The mass ratio (E/B) is 0.01 to 2.0.

(6) The surface treatment agent for galvanized steel sheets according to any one of (1) to (5), further comprising a compound (F), wherein the compound (F) is composed of a water-soluble polymer and an aqueous emulsion resin. At least one of the groups.

(7) A surface treatment agent for a galvanized steel sheet according to (6), wherein a mass ratio of the mass of the compound (B) to SiO ₂ and a mass of the compound (F) (F/B) is 0.01 to 30.

(8) A surface treatment method for galvanized steel sheets, which is coated on a surface of a galvanized steel sheet with a surface treatment agent for galvanized steel sheets of (1) to (7), and dried by heating to form a surface of the galvanized steel sheet. The film amount is 25 to 1000 mg/m ² of the film.

(9) A galvanized steel sheet having a film obtained by a surface treatment method of the galvanized steel sheet of (8).

Therefore, the present invention can provide a surface treatment agent for a galvanized steel sheet which can obtain a surface-treated galvanized steel sheet having excellent properties such as corrosion resistance and corrosion resistance after alkali degreasing, in particular, corrosion resistance of the formed film, The balance between the appearance and the grounding property is good, and the condensation resistance and the coating property (coating film adhesion) also show excellent balance characteristics. Further, the present invention can provide a surface-treated galvanized steel sheet which can be produced by a conventionally used treatment method (a showering roll or a spray squeezing roll) in a manufacturing apparatus for a galvanized steel sheet.

Hereinafter, the surface treatment agent for a galvanized steel sheet according to the present invention, a surface treatment method using the treatment agent, and a galvanized steel sheet having a film obtained by the surface treatment method will be described.

First, the surface treatment agent for galvanized steel sheets will be described.

<Surface treatment agent for galvanized steel sheet>

A surface treatment agent for a galvanized steel sheet according to the present invention, which comprises: ammonium zirconium carbonate (A); and a compound (B) having two or more of one molecule represented by -SiR ¹ R ² R ³ (wherein, R ¹ , R ² and R ³ are each independently a functional group (a) having an alkyl group having 1 to 4 carbon atoms, an alkoxy group or a hydroxyl group, and a molecular weight of 1 unit of the functional group (a) (average molecular weight / The functional group number is in the range of 100 to 5,000; the organic phosphonic acid (C) represented by the formula (1); the metal compound (D) contains a compound selected from the group consisting of Zr, Ti, Co, Fe, V, Ce, Mo, and Mn. And at least one or more metal elements of the group consisting of Mg, Al, Ni, Ca, W, Nb, Cr, and Zn; and water; and a treatment agent having a pH of 6 to 11.

Hereinafter, each component contained in the surface treatment agent for galvanized steel sheets will be described.

<Iron ammonium carbonate (A)>

The surface treatment agent for galvanized steel sheets of the present invention contains ammonium zirconium carbonate (A). Ammonium zirconium carbonate mainly imparts effects such as corrosion resistance, corrosion resistance after alkali degreasing, heat resistance, weldability, continuous processability, and dew condensation resistance to the obtained film.

More specifically, the content of the carbonic acid and the ammonium in the ammonium zirconium carbonate is not particularly limited, and the total of the treatment agent is superior to the viewpoint of the corrosion resistance of the obtained film, the corrosion resistance after alkali degreasing, and the dew condensation resistance. The solid content is preferably from 0.1 to 70% by mass, more preferably from 1 to 50% by mass. Further, the total solid content means a solid component constituting a film to be described later, and does not contain a solvent or the like.

<compound (B)>

The surface treatment agent for a galvanized steel sheet according to the present invention contains the compound (B), and has two or more of one molecule represented by -SiR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ are each Independently, a functional group (a) having an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a hydroxyl group, and a molecular weight (average molecular weight/number of functional groups) of 1 unit of functional group (a) is in the range of 100 to 5,000. .

It is presumed that the compound (B) undergoes a cross-linking reaction with zirconium produced by the above-mentioned ammonium zirconium carbonate to form a film having a three-dimensional crosslinked structure, so that the corrosion resistance of the obtained film, the corrosion resistance after alkali degreasing, and the heat resistance can be improved. , weldability, continuous processability, and condensation resistance. Further, it is presumed that the functional group (a) of the compound (B) is excellent in adhesion to a substrate described later, so that the appearance of the obtained film and the coating property (coating film adhesion) can be improved. Further, it is presumed that the molecular weight (average molecular weight/number of functional groups) per unit functional group (a) is in the range of 100 to 5,000, so that the grounding property and the anti-fingerprint property of the film can be improved.

Various properties can be improved by using the above compound (B) in combination with the above ammonium zirconium carbonate. In particular, it is possible to produce a film which exhibits excellent corrosion resistance and grounding properties which cannot be obtained by using a single individual substance.

The compound (B) has two or more of one molecule and is represented by -SiR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ are each independently and represent an alkyl group having 1 to 4 carbon atoms, A functional group (a) of an alkoxy group or a hydroxy group. Among them, 2 to 8 are preferred. Further, when only one functional group (a) is contained in one molecule, the adhesion to the surface of the galvanized steel sheet is lowered, which is not preferable.

R ¹ , R ² and R ³ are each independently and represent an alkyl group having 1 to 4 carbon atoms, an alkoxy group or a hydroxyl group. Among them, an alkoxy group and a hydroxyl group are preferred.

Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. Among them, a methyl group and an ethyl group are preferable.

The alkoxy group is preferably, for example, an alkoxy group having 1 to 3 carbon atoms.

The compound (B) is preferably one unit functional group (a) having a molecular weight (average molecular weight/number of functional groups) in the range of from 100 to 5,000, more preferably in the range of from 120 to 4,000, particularly preferably in the range of from 150 to 3,000. . When the molecular weight of the one-unit functional group (a) is less than 100, it is difficult to synthesize a compound, and the obtained film is deteriorated in corrosion resistance and adhesion, which is not preferable. On the other hand, when the molecular weight of the one-unit functional group (a) exceeds 5,000, the adhesion of the surface of the galvanized steel sheet due to the characteristic of the functional group (a) is lowered, which is not preferable.

Further, as a method for measuring the above molecular weight, measurement can be carried out by gel permeation chromatography (GPC) or NMR.

Further, the skeleton of the compound (B) is not particularly limited, and is preferably a bond having an ester bond, an ether bond, a guanamine bond, an amino formate bond, a urea bond, or a vinyl bond.

The method for producing the compound (B) is not particularly limited, and examples thereof include (1) a method of reacting a compound having two or more active hydrogen-containing functional groups with chlorodecane; and (2) making a coupling with a vinyl group having a vinyl group. a method of reacting (polymerizing) a copolymerized ethylene compound; (3) a method of reacting a decane coupling agent having a specific reactive functional group with a compound having a functional group reactive with the reactive functional group; 4) A method of modifying a hydrophilic group of a polyfunctional decane coupling agent, and the like.

Among them, (2) or (3) is preferred, and (3) is preferred. Hereinafter, each manufacturing method will be described.

One of the preferred embodiments of the compound (B) is a compound (reaction product) obtained by reacting (polymerizing) a copolymerizable vinyl compound with a vinyl decane coupling agent. Further, the method is as in the production method of the above (2).

The decane coupling agent having a vinyl group is not particularly limited as long as it has a vinyl group, and examples thereof include γ-methyl propylene oxypropyl triethoxy decane, ethylene trichloro decane, and ethylene trimethoxy decane.

Further, the copolymerizable ethylene compound is not particularly limited, and examples thereof include acrylic acid, butyl acrylate, methyl acrylate, and 2-hydroxyethyl methacrylate.

The reaction form of the above compound is not particularly limited, and examples thereof include anionic polymerization, cationic polymerization, and radical polymerization. Among them, radical polymerization is preferred. Further, a conventional polymerization initiator or the like can be suitably used in accordance with the reaction form selected.

Further, a suitable solvent may be used in the reaction, and examples thereof include methanol, ethanol, propanol, isopropanol, acetone, methyl ethyl ketone, diethyl hydroxide, water, and the like.

The other preferred embodiment of the compound (B) includes a decane coupling agent having a reactive functional group (b1) and a functional group (b2) having a reactive functional group (b1). The compound obtained by the reaction of the compound (reaction product).

The reactive functional group (b1) is not particularly limited as long as it can react with other functional groups to form a bonded group. For example, it is preferably selected from the group consisting of an epoxy group, an amine group, a thiol group, a propyloxy group, and an anthracene group. a functional group in a group consisting of a ureido group, an isocyanate group, and a vinyl group. Among them, an epoxy group and an amine group are preferred.

One of the preferred embodiments of the decane coupling agent having a reactive functional group (b1) is a compound represented by the formula (2).

In the formula (2), X represents any one selected from the group consisting of an epoxy group, an amine group, a thiol group, a propyloxy group, a ureganyl group, an isocyanate group, and a vinyl group. Among them, an epoxy group and an amine group are preferred.

In the formula (2), L represents a divalent linking group or only a bonding.

Examples of the linking group represented by L include an alkylene group (preferably having 1 to 20 carbon atoms), -O-, -S-, an extended aryl group, -CO-, -NH-, -SO ₂ -, -COO-, -CONH-, or a combination of these. Among them, an alkyl group is preferred. When only the bonding is indicated, X representing the general formula (2) is directly bonded to Si (germanium atom).

In the formula (2), Y is independently an alkyl group, an alkoxy group or a hydroxyl group having a carbon number of 1 to 4. Among them, an alkoxy group having 1 to 3 carbon atoms and a hydroxyl group are preferable.

Examples of the decane coupling agent having a reactive functional group (b1) include 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, and 2 Epoxy decane such as (3,4-epoxycyclohexyl)ethyltrimethoxydecane; N-(2-aminoethyl)3-aminopropylmethyldimethoxydecane, N-(amine B 3-aminopropyltrimethoxydecane, and amino decane such as 3-aminopropyltriethoxydecane; thiol decane such as 3-thiolpropyltrimethoxydecane; 3-iso Hydrogenated acid propyl trimethoxy decane, 3-hydrogen acrylate triethoxy decane, etc.; hydrogenated vinyl decane; ethylene triethoxy decane, p-styrene trimethoxy decane, etc. Decane and so on.

The functional group (b2) in the compound having a functional group (b2) is not particularly limited as long as it can react with the above reactive functional group (b1), and is preferably an epoxy group, an amine group, a thiol group or a propylene group. The group is a ureido group, an isocyanate group, a vinyl group or the like, and among them, an epoxy group or an amine group is preferred. Among them, a functional group different from the above reactive functional group (b1) is preferred.

Examples of the compound having a functional group (b2) include a decane coupling agent exemplified as the above-described decane coupling agent having a reactive functional group (b1), or an amine compound such as ethylene diamine or aminopropyl thiol; An ether compound such as methyl propane polyepoxypropyl ether or neopentyl alcohol polyepoxypropyl ether.

Among them, a decane coupling agent exemplified as a decane coupling agent having a reactive functional group (b1) is preferred. That is, the compound (B) is preferably a reaction product of a decane coupling agent having a reactive functional group (b1) and a decane coupling agent having a functional group (b2) reactive with the functional group (b1).

The reaction ratio of the decane coupling agent having a reactive functional group (b1) to the compound having a functional group (b2) is not particularly limited, and a decane coupling agent: a compound (mole ratio) = 9:1 to 1: 9, better is 7:3 ~ 3:7.

The reaction conditions are selected according to the compound to be used, and the optimum conditions are selected. Further, a solvent (for example, an alcohol or the like) or the like may be used in the reaction.

The content of the compound (B) in the surface treatment agent for a galvanized steel sheet is not particularly limited, and the relative treatment agent is superior in terms of corrosion resistance, fingerprint resistance, appearance, grounding property, and coating property of the obtained film. The total solid content in the medium is preferably from 0.1 to 70% by mass, more preferably from 1 to 50% by mass.

<Organic phosphonic acid (C)>

The surface treatment agent for galvanized steel sheets according to the present invention contains an organic phosphonic acid represented by the formula (1). It is presumed that these compounds react with the galvanized steel sheet to form a poorly soluble salt, so that the corrosion resistance and the coating property (coating adhesion) of the film can be improved. In addition, in order to stably dissolve the metal compound (D) to be described later in the aqueous treatment liquid, an organic phosphonic acid is required, so that the storage stability of the surface treatment agent for galvanized steel sheet is improved.

The content of the organic phosphonic acid (C) in the surface treatment agent for a galvanized steel sheet is not particularly limited, and the corrosion resistance of the obtained film, the corrosion resistance after alkali degreasing, the grounding property, and the dew condensation resistance are further improved. The total solid content in the treating agent is preferably from 0.05 to 50% by mass, more preferably from 0.1 to 30% by mass.

<Metal Compound (D)>

The surface treatment agent for a galvanized steel sheet according to the present invention contains a group selected from the group consisting of Zr, Ti, Co, Fe, V, Ce, Mo, Mn, Mg, Al, Ni, Ca, W, Nb, Cr, and Zn. a metal compound (D) of at least one metal element. The metal compound (D) forms a poorly soluble salt with the above organic phosphonic acid (C). Therefore, it is estimated that the immobilization of the organic phosphonic acid (C) in the film can improve the condensation resistance and coating property (coating adhesion) of the film.

The metal compound (D) is not particularly limited as long as it contains the above-mentioned metal element, and examples thereof include a nitrate, a sulfate, an acetate, a phosphate, an ammonium salt, a fluoride, and the like of the above metal.

More specifically, examples of the metal compound containing Zr include zirconium nitrate, zirconyl nitrate, zirconyl acetate, zirconium ammonium fluoride, zirconyl sulfate, zirconium hydrofluoric acid, and zirconia sol. . Further, zirconium acid and a salt thereof obtained by ion-exchange or alkali-neutralizing an aqueous solution of a water-soluble zirconium salt can also be mentioned.

Examples of the metal compound containing Ti include titanyl sulfate, titanium oxynitride, titanium nitrate, titanium oxychloride, titanium chloride, titanium oxide sol, titanium oxide, titanium ammonium fluoride, potassium oxalate titanate, and titanium lactate. Acetylacetone titanium, diisopropyl titanium diacetone acetone, and the like. Further, a metatitanic acid obtained by thermally hydrolyzing an aqueous solution of titanyl sulfate or an orthotitanic acid obtained by neutralization with a base and salts thereof may be mentioned.

Examples of the metal compound containing Co include cobalt sulfate, cobalt nitrate, cobalt carbonate, cobalt phosphate, cobalt chloride, cobalt oxide, and cobalt hydroxide.

Examples of the metal compound containing Fe include iron sulfate, iron nitrate, iron chloride, iron phosphate, iron oxide, iron hydroxide, iron powder, and the like.

Examples of the metal compound containing V include vanadium pentoxide, ammonium metavanadate, sodium metavanadate, vanadium trioxide, vanadium trioxide, vanadium oxychloride, vanadyl sulfate, vanadyl oxyacetate, and vanadium. Ethylene acetonide vanadium, vanadium trichloride, phosphorus vanadium molybdate, vanadium sulfate, and the like.

Examples of the metal compound containing Ce include cerium nitrate, cerium acetate, cerium chloride, cerium sol, and the like.

Examples of the metal compound containing Mo include ammonium molybdate, sodium molybdate, potassium molybdate, ammonium molybdate phosphate, and sodium molybdate phosphate.

Examples of the metal compound containing Mn include potassium permanganate, ammonium permanganate, sodium permanganate, permanganate, manganese sulfate, manganese nitrate, manganese oxide, manganese carbonate, manganese chloride, manganese phosphate, and the like. .

Examples of the metal compound containing Mg include magnesium sulfate, magnesium nitrate, magnesium carbonate, magnesium phosphate, magnesium chloride, magnesium oxide, and magnesium hydroxide.

Examples of the metal compound containing Al include alumina, aluminum hydroxide, aluminum sulfate, aluminum nitrate, aluminum phosphate, and aluminum chloride.

Examples of the metal compound containing Ni include nickel oxide, nickel hydroxide, nickel sulfate, nickel nitrate, nickel phosphate, and nickel chloride.

Examples of the metal compound containing Ca include calcium oxide, calcium hydroxide, calcium sulfate, calcium nitrate, calcium phosphate, and calcium chloride.

Examples of the metal compound containing W include ammonium metatungstate, sodium metatungstate, potassium metatungstate, paratungstic acid, ammonium paratungstate, and sodium paratungstate.

Examples of the metal compound containing Nb include cerium oxalate, cerium oxide, cerium sol, and the like.

Examples of the metal compound containing Cr include trivalent chromium, chromium sulfate, chromium nitrate, chromium chloride, chromium hydroxide, chromium oxide, and chromium phosphate.

Examples of the metal compound containing Zn include zinc oxide, zinc hydroxide, zinc sulfate, zinc nitrate, zinc chloride, zinc phosphate, and acetylated zinc. In addition, since zinc is an amphoteric metal, a base is used. The resulting sodium zincate, potassium zincate, and the like.

Among these, from the viewpoint of high effect of improving corrosion resistance, a metal compound containing V, Mg, Al, or Zn, and the like are preferable.

The content of the metal compound (D) in the surface treatment agent for galvanized steel sheets is not particularly limited, and is excellent in corrosion resistance of the obtained film, corrosion resistance after alkali degreasing, weldability, continuous processability, appearance, and dew condensation resistance. From the viewpoint of the total solid content in the treatment agent, it is preferably from 0.01 to 40% by mass, more preferably from 0.1 to 30% by mass.

<water>

The surface treatment agent for galvanized steel sheets according to the present invention contains water as a solvent.

The content of the water in the surface treatment agent for galvanized steel sheets is not particularly limited, and from the viewpoint of easier use of the treatment agent, the total amount of the treatment agent is preferably from 30 to 99% by mass, more preferably from 40 to 95. quality%.

<pH>

The pH of the surface treatment agent for galvanized steel sheets of the present invention is preferably from 6 to 11, more preferably from 7 to 10. When the pH is less than 6, the ammonium zirconium carbonate will not be stably dissolved, and the stability of the surface treatment agent for the galvanized steel sheet will be deteriorated. When the pH exceeds 11, the workability is deteriorated due to the remarkable ammonium odor, and the obtained film performance is also poor.

The adjustment of the pH is preferably carried out using ammonia, carbonic acid, acetic acid, nitric acid or the like. Further, it is presumed that the pH is adjusted to 6 to 11, which suppresses excessive etching of the galvanized steel sheet by the treatment agent, and improves the grounding property of the surface-treated galvanized steel sheet.

In the treatment agent, the mass ratio when the Zr (Zr mass) in the ammonium zirconium carbonate (A) is converted into ZrO ₂ and the mass in the compound (B) in terms of Si (Si mass) in terms of SiO ₂ ( A/B) is preferably from 0.01 to 6.0, more preferably from 0.1 to 4.0. If it is less than 0.01, the components which are easily dissolved may be increased, and the corrosion resistance and the dew condensation resistance of the film after alkali degreasing may be lowered. On the other hand, when it exceeds 6.0, the film may become hard, and coatability (coating adhesiveness) may fall.

In the treatment agent, the mass ratio (C/B) of the mass of the organic phosphonic acid (C) to the mass of Si in the compound (B) in terms of SiO ₂ is preferably 0.01 to 5.0, more preferably 0.05 to ～. 4.0, the best is 0.05 to 3.0. If it is less than 0.01, the corrosion resistance of the film may be deteriorated. When it exceeds 5.0, the corrosion resistance and the dew condensation resistance of the film after alkali degreasing may be deteriorated.

In the treatment agent, the mass ratio (D/B) of the mass of the metal element in the metal compound (D) to the mass in the conversion of Si in the compound (B) to SiO ₂ is preferably 0.01 to 4.0, more preferably It is 0.05 to 3.0. If it is less than 0.01, the effect of improving the corrosion resistance of the film may not be obtained. If it exceeds 4.0, the amount of the dissolved component may increase, and the corrosion resistance of the film may be lowered.

In addition to the above-mentioned compound, the surface treatment agent for a galvanized steel sheet according to the present invention may further contain at least one compound (F) of the following metal alkoxide (E) and a water-soluble polymer and a water-based emulsion resin. .

Hereinafter, each component will be described.

<Metal alkoxide (E)>

The surface treatment agent for galvanized steel sheets of the present invention may also contain a metal alkoxide (E). More specifically, it may contain a metal alkoxide (E) containing at least one metal element selected from the group consisting of B, Nb, Si, Ta, Ti, V, W, and Zr.

The surface treatment agent for a galvanized steel sheet according to the present invention provides a film excellent in corrosion resistance (particularly in a processed portion) by containing a metal alkoxide (E). The metal alkoxide (E) is presumed to promote the crosslinking reaction of the above compound (B) to form a film having a denser network structure. Although the reason is not clear, it is preferably selected from Si and Ti from the viewpoint of particularly improving corrosion resistance.

The metal alkoxide (E) is not particularly limited as long as it has an alkoxy group directly bonded to a metal, and conventionally known ones can be appropriately selected and used. The alkoxy group directly bonded to the metal alkoxide may be a hydrolyzed hydroxyl group.

Among them, preferred is a general formula Me(OR)n (wherein R is independently and represents an alkyl group or a hydrogen atom, at least one of which is an alkyl group. n represents a valence of a metal. Me represents the above metal) Expressed as a compound.

The alkyl group represented by R is preferably an alkyl group having 1 to 4 carbon atoms.

Examples of the metal alkoxide (E) include titanium tetraisopropoxide, titanium tetraethoxide, titanium butadiene dimer, tetra-2-ethylhexyltitanium oxide, vanadium oxyethylene trioxide, and triisopropyloxide. Vanadium, zirconia, tetraethylene zirconia, tetrapropoxide zirconia, tetramethoxynonane oxime, tetramethoxy decane, tetraethoxy decane, tetra-n-propoxy decane, methyl trimethoxy decane, A Triethoxy decane, dimethyl dimethoxy decane, dimethyl diethoxy decane, methyl triethoxy decane, cyclohexyl methyl dimethoxy decane, n-hexyl trimethoxy decane, Diphenyldimethoxydecane, diphenyldiethoxydecane, phenyltrimethoxydecane, phenyltriethoxydecane, decyltrimethoxydecane,octadecyltrimethoxydecane,18 Triethoxy decane, isobutyl trimethoxy decane, and the like.

In a preferred embodiment of the metal alkoxide (E), from the viewpoint of further improving the corrosion resistance of the obtained film and the corrosion resistance after alkali degreasing, an alkoxysilane containing a Si element is preferable, particularly The tetraalkyloxane of Si(OR) ₄ (R represents an alkyl group) is more preferable.

The content of the metal alkoxide (E) in the surface treatment agent for galvanized steel sheets is not particularly limited, and the total solid content in the treatment agent is preferably from the viewpoint of further excellent corrosion resistance of the obtained film. It is 0.01 to 50% by mass, more preferably 0.1 to 30% by mass.

In the treatment agent, the mass ratio (E/B) of the mass of the metal element contained in the metal alkoxide (E) to the mass of Si in the compound (B) in terms of SiO ₂ is preferably 0.01 to 2.0. More preferably, it is 0.5 to 1.5. If it is less than 0.01, the effect of improving the corrosion resistance of the film may not be obtained. When it exceeds 2.0, the amount of the dissolved component in the film may increase, and the corrosion resistance may be lowered.

<Water-soluble polymer and/or aqueous emulsion resin>

The surface treatment agent for a galvanized steel sheet according to the present invention may contain at least one compound (F) of a group consisting of a water-soluble polymer and an aqueous emulsion resin. By the addition of these components, the anti-fingerprint property, corrosion resistance, and lubricity of the film can be improved.

The water-soluble polymer and/or the aqueous emulsion resin are not particularly limited, and examples thereof include water-soluble polymers such as polyacrylic acid, polymethacrylic acid, polypropylene decylamine, and polyvinyl alcohol, and acrylic resins dispersed in water. , urethane resin, epoxy resin, polyester resin, polyamide resin, polyolefin resin, ethylene-acrylic resin, polybutyraldehyde resin, fluororesin, and the like.

The total content of the compound (F) in the surface treatment agent for a galvanized steel sheet is not particularly limited, and the relative treatment of the obtained film is more excellent in corrosion resistance, fingerprint resistance, dew condensation resistance, and coating property. The total solid content in the agent is preferably from 0.1 to 90% by mass, more preferably from 1 to 70% by mass.

In the treatment agent, the mass ratio (F/B) of the mass of the compound (F) to the mass of Si in the compound (B) in terms of SiO ₂ is preferably from 0.01 to 30, more preferably from 0.1 to 20. If it is less than 0.01, the fingerprint resistance and lubricity of the film may not be improved, and if it exceeds 30, the corrosion resistance and heat resistance of the film may be lowered.

<fluorine compound>

The surface treatment agent for galvanized steel sheets of the present invention may also contain fluoride as needed. In particular, in a hot-dip galvanized steel sheet having a thick surface oxide film, if a fluoride is added to enhance the etching property of the treatment agent, the reaction layer (non-conductive layer) on the surface of the material is thickened, and further improvement is expected. Corrosion resistance improvement effect. However, when the fluoride is added to the treatment agent, the etching property is increased, so that the grounding property may be lowered as the portion other than the surface oxide film is dissolved. In addition, the amount of Zn or Fe mixed in the aqueous treatment liquid may increase, and the stability of the surface treatment agent for the galvanized steel sheet may be lowered, and the treatment for generating fluorine in the disposal of the liquid may be caused. Therefore, it is preferably implemented within the scope of the above problems.

The content of the fluoride in the surface treatment agent for a galvanized steel sheet according to the present invention is not particularly limited, and the upper limit of fluorine in 1 kg of the treatment agent is preferably 50 g.

Further, examples of the fluoride include ammonium fluoride, ammonium hydride fluoride, ammonium titanium fluoride, and ammonium zirconium fluoride.

<antifoaming agent>

The surface treatment agent for galvanized steel sheets of the present invention may optionally contain an antifoaming agent (G). The surface treatment agent for a galvanized steel sheet containing the antifoaming agent preferably forms a film on the surface of the galvanized steel sheet by spraying on a galvanized steel sheet by a spray or a shower, and then using a roller or an air brake The coating amount was adjusted, and then dried at 50 to 250 ° C as the highest reaching plate temperature.

The antifoaming agent is not particularly limited, and a type which has been subjected to stable emulsification such as mineral oil, fatty acid or cerium oxide, or a type of water-soluble active agent can be used. You can also combine the two.

The content of the antifoaming agent in the surface treatment agent for galvanized steel sheets of the present invention is appropriately selected in accordance with the kind to be used, and is preferably 0.1 to 3.0 g per 1 kg of the treatment liquid. If the content of the antifoaming agent is too small, the defoaming property cannot be obtained; if it is too large, the coating property is not good.

<Lubricant>

The surface treatment agent for galvanized steel sheets of the present invention may optionally contain an additive (lubricant) for improving lubricity. The lubricant improves the lubricity of the surface treatment film to prevent scratching, and is effective for reducing the damage of the galvanized steel sheet during processing.

Examples of the lubricant include solid lubricants such as polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, carnauba wax, paraffin, montan wax, and Teflon (registered trademark). One or two or more of these solid lubricants are used.

The content of the lubricant in the surface treatment agent for galvanized steel sheets of the present invention is not particularly limited, but is preferably at most 50 g per 1 kg of the treatment liquid. If this value is exceeded, not only will it be impossible to add it calmly, but it will also hinder the original purpose.

The surface treatment agent for a galvanized steel sheet according to the present invention may optionally contain a solvent other than the above water (for example, an alcohol or the like).

The method for preparing the surface treatment agent for a galvanized steel sheet according to the present invention is not particularly limited. For example, ammonium zirconium carbonate (A), a compound (B), an organic phosphonic acid (C), a metal compound (D), other additives, and water can be sufficiently mixed by using a stirrer such as a mixing homogenizer.

<Surface treatment method>

The surface treatment method for the surface treatment agent for a galvanized steel sheet according to the present invention is not particularly limited, but it is preferably a surface treatment method in which the surface treatment agent for the galvanized steel sheet is applied onto the surface of the galvanized steel sheet and dried. On the surface of the galvanized steel sheet, a film having a film amount of 25 to 1000 mg/m ² was formed.

Hereinafter, the surface treatment method will be described.

Prior to coating, the galvanized steel sheet may be pretreated as needed to achieve the purpose of removing oil or dirt on the surface of the galvanized steel sheet. Galvanized steel sheets are often coated with anti-rust oil based on anti-rust purposes. In addition, even if the anti-rust oil is not coated, there will be oil or dirt adhering to the operation. The surface of the galvanized steel sheet is washed by pre-treatment, and the surface of the galvanized steel sheet can be uniformly wetted by the surface treatment agent for the galvanized steel sheet of the present invention. Further, in the case where the surface of the material is uniformly wetted with the surface treatment agent for the galvanized steel sheet of the present invention without oil or dirt, etc., there is no particular need for a pretreatment step.

Further, the method of the pretreatment is not particularly limited, and examples thereof include a method of washing with hot water, washing with a solvent, and washing with an alkali degreasing.

Examples of the galvanized steel sheet to be used include a hot-dip galvanized steel sheet (GI), an alloyed hot-dip galvanized steel sheet (GA) after alloying, and a hot-dip Zn-5% Al alloy steel sheet (GF), and hot-dip plating. Zinc-55% aluminum alloy steel plate (GL), electrogalvanized steel plate (EG), electrogalvanized nickel-nickel alloy steel plate (Zn-Ni), and the like. In addition, it can also be applied to iron plates that are not plated.

The method of applying the galvanized steel sheet as the treatment agent of the present invention is not particularly limited as long as the treatment agent can be uniformly applied to the surface of the galvanized steel sheet, and examples thereof include a roll coating method, a dipping method, and a spray coating method.

Further, the treatment (coating) temperature and the treatment (coating) time are also not particularly limited, and generally the treatment (coating) temperature is preferably 10 to 40 ° C, and the treatment (coating) time is preferably 0.1 to 10 second.

The heating temperature at the time of coating the film formed on the surface of the dry galvanized steel sheet is preferably 50 to 250 ° C, more preferably 60 to 180 ° C. The heating and drying method is not particularly limited, and the treatment agent can be dried by heating with hot air, an induction heater, ultraviolet rays, near infrared rays or the like.

Further, the heating time is selected according to the kind of the compound in the surface treatment agent for galvanized steel sheets to be used, and the like. Among them, from the viewpoint of productivity and the like, it is preferably from 0.1 to 60 seconds, more preferably from 1 to 30 seconds.

The amount of the film formed on the surface of the galvanized steel sheet is preferably from 25 to 1,000 mg/m ² , more preferably from 50 to 800 mg/m ² , most preferably from 100 to 600 mg/m ² . When the amount is less than 25 mg/m ² , the surface treatment agent for the galvanized steel sheet cannot be uniformly applied to the surface of the steel sheet, so that various properties such as the desired workability, corrosion resistance, and coating properties cannot be exhibited in a balanced manner. When it exceeds 1000 mg/m ² , the appearance will be lowered, and the coatability will be deteriorated. In addition, the grounding property and the weldability are deteriorated. Further, in the press working, the amount of peeling of the film is increased, which causes an obstacle not only in press forming but also in manufacturing cost.

Further, the above film amount means the amount of the film on one side of the steel sheet.

An organic polymer film having a film thickness of 0.1 to 3.0 μm after drying is formed on the film formed by the surface treatment method to impart higher corrosion resistance, fingerprint resistance, and lubricity. As the organic polymer film, a resin emulsion such as a conventional acrylic resin, a urethane resin or an epoxy resin, or a ruthenium, a rust inhibitor, a lubricant, an ultraviolet absorber, a pigment or the like may be added thereto.

By using the surface treatment agent for the galvanized steel sheet of the present invention for surface treatment, a surface treatment film having corrosion resistance, heat resistance, weldability, continuous processability, grounding property, and anti-fingerprint property can be formed on the surface of the galvanized steel sheet. In particular, the formed film not only has good corrosion resistance and appearance, but also exhibits excellent balance characteristics in terms of condensation resistance and coating property (coating film adhesion).

The coating amount in the spray and winch coating method is usually about 1 to 3 g/m ² . Further, from the viewpoint of usability (uniform coating), a treatment liquid in which the solid content concentration of the surface treatment agent is adjusted to 10 to 20% by mass is used. The surface treatment agent can be adjusted to 10 to 20% by mass, and when it is applied by this method, a film of 100 to 600 g/m ² can be obtained, and the degree of volatilization of water in terms of drying is sufficient. In short, since the intended properties can be obtained with such a small amount of film, the surface-treated galvanized steel sheet of the present invention can be produced by these methods. Thereby, the required steel sheet can be produced in a manner that does not require new production equipment and does not reduce the productivity of the compact production line (CGL, EGL).

As described above, according to the present invention, a surface-treated galvanized steel sheet having corrosion resistance, heat resistance, weldability, continuous processability, grounding property, and anti-fingerprint property can be realized, and in particular, the formed film is excellent in corrosion resistance and appearance. Moreover, the condensation resistance and the coating property (coating film adhesion) also showed excellent characteristics of balance.

Such a steel plate can be effectively used for materials used in various fields such as construction, electrical, and automobiles. In addition, it is produced in the galvanizing line (CGL) because it can be produced using the same processing equipment as the conventional temporary rust-resistant chromate treatment, so it is more productive and more effective.

Example

The effects of the present invention will be specifically described below by way of examples, but the present invention is not limited to the following examples, and designs that are changed as conditions change are also included in the technical scope of the present invention.

(1) Test materials

The following commercially available materials were used as test materials.

(i) Electrogalvanized steel sheet (EG): plate thickness 0.8 mm, plating amount = 20/20 (g/m ² )

(ii) hot-dip galvanized steel sheet (GI): sheet thickness 0.8mm, plating amount = 60/60 (g / m 2)

(iii) alloyed hot-dip galvanized steel sheet (GA): plate thickness 0.8 mm, plating amount = 40/40 (g/m ² )

Further, the amount of plating indicates the amount of plating on the main surface of the steel sheet. For example, in the case of an electrogalvanized steel sheet, it is 20/20 (g/m ² ), that is, it means that the both sides of the steel sheet have a plating layer of 20 g/m ² , respectively.

(2) pre-treatment (washing)

The test plate was first prepared by treating the surface of the above test material with Palklin N364S manufactured by Nihon Parkerizing Co., Ltd., and removing oil and dirt on the surface. Then, it was washed with tap water, and it was confirmed that the surface of the galvanized steel sheet was 100% wetted with water, and then rinsed with pure water, and the moisture was removed in an oven at 100 ° C ambient atmosphere, and this was used as a test plate.

(3) Modification of treatment agent for galvanized steel sheet

Each component was mixed in water in the amounts shown in Table 1 (Examples 1 to 49 and Comparative Examples 50 to 65) to prepare a treatment liquid.

In addition, the blending amount of the components (A) to (F) in Table 1 indicates the blending amount (g) in the surface treatment liquid for a 1 kg galvanized steel sheet. Further, components other than the components (A) to (F) contained in the respective treatment liquids are mainly water.

Further, the blending amount of the component (A) in Table 1 indicates the mass (g) when Zr (Zr mass) in the ammonium zirconium carbonate (A) is converted into ZrO ₂ . The blending amount of the component (B) in Table 1 indicates the mass (g) when Si (Si mass) in the compound (B) is converted into SiO ₂ . The compounding amount of the component (D) in Table 1 means the mass (g) of the metal element in the metal compound (D). The compounding amount of the metal alkoxide (E) in Table 1 means the mass (g) of the metal element contained in the metal alkoxide (E).

Further, the mass ratio (A/B) in Table 1 represents the mass ratio of the mass in the case of Zr in the ammonium carbonate (A) to ZrO ₂ and the mass in the compound (B) in terms of SiO ₂ . . The mass ratio (C/B) indicates the mass ratio of the mass of the organic phosphonic acid (C) to the mass of Si in the compound (B) in terms of SiO ₂ . The mass ratio (D/B) indicates the mass ratio of the mass of the metal element in the metal compound (D) to the mass in the case where Si in the compound (B) is converted into SiO ₂ . The mass ratio (E/B) is a mass ratio of the mass of the metal element contained in the metal alkoxide (E) to the mass of Si in the compound (B) in terms of SiO ₂ . The mass ratio (F/B) is a mass ratio of the mass of the compound (F) to the mass of Si in the compound (B) in terms of SiO ₂ .

Hereinafter, the compounds used in Table 1 will be described.

<Iron ammonium carbonate (A)>

A1: ammonium zirconium carbonate

<compound (B)>

B1: The product was obtained by reacting hexamethylenediamine 1 molar with γ-glycidoxypropyltrimethoxydecane 2 molar in ethanol. Thereafter, the mixture was diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the product 1 obtained was two, and the molecular weight (average molecular weight/number of functional groups) of the one-unit functional group (a) was about 294.

B2: #828 type bisphenol A type epoxy resin (Japanese epoxy resin loose) 1 mole, and γ-aminopropyl triethoxy decane 2 mole in N-methyl-2-pyre The reaction is carried out in an alkyl ketone to obtain a product. Thereafter, the mixture was diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the product 1 obtained was two, and the molecular weight (average molecular weight/number of functional groups) of the one-unit functional group (a) was about 411.

B3: obtained by emulsion polymerization of 1 mol of acrylic acid, butyl acrylate 5 mol, methyl methacrylate 5 mol and γ-methyl propylene oxypropyl triethoxy decane 3 mol in deionized water. Product. Thereafter, the mixture was diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the product 1 obtained was three, and the molecular weight (average molecular weight/number of functional groups) of the one-unit functional group (a) was about 694.

B4: Aminopropyltriethoxydecane 1 molar was reacted with γ-glycidoxypropyltrimethoxydecane 2 mole in ethanol to obtain a product. Thereafter, deionized water was added and diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the product 1 obtained was two, and the molecular weight (average molecular weight/number of functional groups) of the one-unit functional group (a) was about 894.

B5: an aqueous urethane resin having a tertiary and a quaternary amine group (registered trademark: ADEKA BONTIGHTER-HUX-760, Asahi Chemical Industry Co., Ltd.) with respect to 100 parts by mass of bis(trimethoxyammoniopropyl)amine Stock system) 200 parts by mass. Then, it was diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the obtained compound 1 is two, and the molecular weight (average molecular weight/number of functional groups) of one unit of the functional group (a) is about 171, bis(trimethoxysulfonylpropyl) The solid component weight ratio (A)/(B) of the amine (A) to the urethane resin (B) is 1/2.

B6: 50 mol of acrylic acid, 100 mol of butyl acrylate, 100 mol of methyl methacrylate, 100 mol of 2-hydroxyethyl methacrylate, and γ-methylpropenyloxypropyl triethoxy The decane 1 mole was emulsion polymerized in deionized water to obtain a product. Thereafter, the mixture was diluted with deionized water to have a solid content concentration of 5% by mass.

Further, the number of the functional groups (a) in the molecule of the product 1 obtained is one, and the molecular weight (average molecular weight/number of functional groups) of the one-unit functional group (a) is about 40,000, which is located in the compound (B). The range of functional group equivalents is outside.

B7: It was diluted with deionized water to a concentration of 5% by mass with respect to γ-thiolpropyltrimethoxydecane.

Further, the number of the functional groups (a) in the molecule of the compound 1 is one, which is outside the scope of the present invention.

<Organic phosphonic acid (C)>

C1:1-hydroxyethylidene-1,1-diphosphonic acid

<Metal Compound (D)>

D1: Ammonium vanadate

D2: Magnesium nitrate

D3: Aluminum nitrate

D4: Zinc oxide

<Metal alkoxide (E)>

E1: titanium isopropoxide

E2: tetraethoxy decane

<compound (F)>

F1: Acrylic resin (made by Showa Polymer Co., Ltd., Polyzole AM-2386)

(4) Processing method

The surface of the galvanized steel sheet is applied to each test plate by a bar coating method or a spray/scratch coating method, and then directly washed in a drying chamber at a drying temperature shown in Table 2, without being washed with water. The film of the film amount shown in Table 2 was formed. Further, the amount of the film means the amount of the film on one side of the steel sheet.

The drying temperature is adjusted in accordance with the ambient temperature in the oven and the time it is placed in the oven. Further, the drying temperature means the temperature at which the surface of the test plate reaches. Specific methods of the bar coating method and the spray & winch coating method are as follows.

Bar coating method: A treatment agent was dropped on a test plate, and coated with a #3 to 5 coating bar. The amount of the coating film is adjusted to a predetermined amount depending on the thickness of the coating bar to be used and the concentration of the treatment liquid.

Spray & Winch Coating Method: The treatment liquid was sprayed on the surface of the test plate to wet the entire surface, and then more liquid was removed by a roller composed of two flat rubber rolls to adjust the coating amount. The amount of water removed by the roller and the concentration of the treatment liquid are adjusted to a predetermined amount of film.

(5) Evaluation test method

(5-1) Corrosion resistance (and corrosion resistance after alkali degreasing)

The obtained surface-treated galvanized steel sheet was cut into a size of 70 × 150 mm, and the inner side and the end portion were attached with cellophane as a test piece, and a salt spray test prescribed in JIS Z2371 was carried out to produce 5% (area ratio) white. The time required for rust is evaluated.

In addition, for the corrosion resistance after alkali degreasing, the same treatment was carried out by a surface-treated galvanized steel sheet which was sprayed with an alkali degreaser (Palklin N364S, Pakkin N364S, Japan) at 20 g/L for 2 minutes at 60 ° C and then washed with water. . The evaluation criteria at this time are as follows.

◎: It takes more than 120 hours to produce 5% white rust.

○: It takes more than 48 hours and less than 120 hours to produce 5% white rust.

△: It takes more than 24 hours and less than 48 hours to produce 5% white rust.

╳: Less than 24 hours after producing 5% white rust

On the other hand, the evaluation criteria for GA are as follows.

◎: It takes more than 48 hours to produce 5% white rust.

○: It takes more than 24 hours and less than 48 hours to produce 5% white rust.

△: It takes more than 12 hours and less than 24 hours to produce 5% white rust.

╳: Less than 12 hours after producing 5% white rust

(5-2) Appearance

The appearance surface of the obtained surface-treated galvanized steel sheet was evaluated. The evaluation criteria at this time are as follows.

◎: no whitening, interference color

○: There is a very thin whitening and interference color

△: There is whitening and interference color

╳: There is significant whitening and interference color

(5-3) Condensation resistance

The obtained surface-treated galvanized steel sheet was placed in a freezer at -5 ° C for 1 hour, and then placed in a high-temperature and constant-humidity bath (50 ° C, humidity 95%) for 2 hours. When the surface-treated galvanized steel sheet was placed in a high-temperature and constant-humidity bath, it was confirmed that water droplets (condensation) were formed on the surface of the surface-treated galvanized steel sheet (if it was not confirmed, it was placed in the freezer for one hour). It was confirmed that the surface of the surface-treated galvanized steel sheet was dried when taken out from the high-temperature and constant-humidity tank (when it was not dried, it was left to stand until the surface was dry).

Water droplets (condensation) on the surface of the surface-treated galvanized steel sheet were visually evaluated. The evaluation criteria at this time are as follows.

◎: no water mark

○: Watermarks are quite difficult to see

△: visible

╳: Visible

(5-4) Coating properties

After the surface-treated galvanized steel sheet was coated with a melamine-based paint ("Aramaic #1000" manufactured by Kansai Paint Co., Ltd.), the thickness of the coating film after firing at 160 ° C was 20 μm. After immersing in boiling water for 1 hour after coating, 100 1 mm square grids were cut out on the coating film, and after extrusion by 5 mm using an Alice Indentation Tester, the tape was peeled off, and the residual ratio of the lattice was evaluated. The evaluation criteria at this time are as follows.

◎: Residual rate 91 to 100%

○: Residual rate 71 to 90%

△: Residual rate 51 to 70%

╳: Residual rate 0 to 50%

(5-5) Grounding

The interlayer resistance of the obtained surface-treated galvanized steel sheet was measured by an interlayer resistance meter. The evaluation was performed by the following criteria.

◎: less than 1Ω

○: 1 Ω or more and less than 2 Ω

△: 2 Ω or more and less than 3 Ω

╳: 3Ω or more

(5-6) Resistance to blackening

The surface of the test object of the obtained surface-treated galvanized steel sheet was combined with each other, wrapped in a kraft paper coated with ethylene on one side, and placed in a thermo-hygrostat having a humidity of 98% at 50 °C. At this time, in order to fix and adhere the surface-treated galvanized steel sheet, 1 kg of a weight was applied to the test piece after the packaging. In this state, it was kept for 10 days, and the appearance of the surface-treated galvanized steel sheet after the removal was visually evaluated in accordance with the following criteria.

◎: no appearance change

○: A very slight discoloration can be seen

△: It can be seen that there is slight blackening or partial blackening.

╳: Visible blackening

The surface-treated galvanized steel sheets obtained by using the surface treatment agent for galvanized steel sheets described in Examples 1 to 49 and Comparative Examples 50 to 65 are subjected to the above (5-1) to (5-6). The evaluation results are shown in Table 3.

In addition, from a practical point of view, there must be no "╳" in the above evaluation items.

Further, in Comparative Example 64, the treatment liquid could not form a film due to instability, and thus various measurements could not be performed.

As shown in Table 3, it is understood that the surface-treated galvanized steel sheet treated by the treatment agent used in a predetermined ratio of the various components defined in the present invention has good corrosion resistance and corrosion resistance after alkali degreasing, and is excellent in appearance and condensation resistance. The property, coatability (coating film adhesion), or grounding property and the like exhibit more excellent balance characteristics. Further, it is also known that an excellent surface-treated galvanized steel sheet can be produced in the spray & winch coating method.

In particular, the treatment agents of the components (A) to (F) which are contained in a quantitative amount exhibit excellent properties in all of the above items. Further, from the comparison between Example 3 and Example 31, it is understood that the component B obtained by reacting the decane coupling agents in the component (B) exhibits more excellent performance. Further, from the comparison between Example 37 and Example 49, it is understood that when alkoxysilane is used as the metal alkoxide, the obtained film properties (corrosion resistance) are further excellent.

In the comparative example, a surface-treated galvanized steel sheet having various properties which were comprehensively satisfactory was not obtained. For example, in Comparative Examples 50 to 56 which did not contain the component B, corrosion resistance and grounding properties were not good. Further, Comparative Example 59 which did not contain the component A was also inferior in corrosion resistance and grounding property. On the other hand, the present invention containing the components A to D and using the component A and the component B can obtain a film excellent in both corrosion resistance and grounding properties.

Claims (9)

A surface treatment agent for a galvanized steel sheet, comprising: ammonium zirconium carbonate (A); and a compound (B) having two or more of one molecule represented by -SiR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ are each independently a functional group (a) having an alkyl group, an alkoxy group or a hydroxyl group having 1 to 4 carbon atoms, and a molecular weight (average molecular weight / number of functional groups) of one unit of the functional group (a) ) is in the range of 100 to 5000; the organic scaly acid (C) represented by the formula (1); the metal compound (D) containing a compound selected from the group consisting of Zr, Ti, Co, Fe, V, Ce, Mo, Mn, Mg At least one or more metal elements of the group consisting of Al, Ni, Ca, W, Nb, Cr, and Zn, wherein the metal compound containing Zr does not contain ammonium zirconium carbonate; and water; and the pH is 6~11; general formula (1) The surface treatment agent for a galvanized steel sheet according to the first aspect of the invention, wherein the mass of Zr in the ammonium zirconium carbonate (A) is converted into ZrO ₂ and the Si in the compound (B) is converted into SiO ₂ The mass ratio (A/B) of the mass is 0.01 to 6.0; the mass ratio (C/B) of the mass of the organic phosphonic acid (C) to the mass of Si in the compound (B) converted to SiO ₂ is 0.01 ~5.0; The mass ratio (D/B) of the mass of the metal element in the metal compound (D) to the mass of Si in the compound (B) in terms of SiO ₂ is 0.01 to 4.0. The surface treatment agent for galvanized steel sheets according to claim 1 or 2, wherein the compound (B) is a decane coupling agent having a reactive functional group (b1), and has a reactive functional group ( B1) The compound of the functional group (b2) of the reaction is reacted, and one of the reactive functional group (b1) and the functional group (b2) is an amino group or an epoxy group. The surface treatment agent for galvanized steel sheets according to claim 1 or 2, further comprising a metal alkoxide (E); the metal alkoxide (E) comprising B, Nb, Si, At least one metal element of the group consisting of Ta, Ti, V, W, and Zr. The surface treatment agent for galvanized steel sheets according to item 4 of the patent application, wherein the mass of the compound (B) in terms of Si converted to SiO ₂ and the mass of the metal element contained in the metal alkoxide (E) The mass ratio (E/B) is 0.01 to 2.0. The surface treatment agent for galvanized steel sheets according to claim 1 or 2, further comprising a compound (F), wherein the compound (F) is composed of a water-soluble polymer and an aqueous emulsion resin. At least one. The surface treatment agent for galvanized steel sheets according to item 6 of the patent application, wherein the mass of the compound (B) in terms of Si in terms of SiO ₂ and the mass ratio (F/B) of the mass of the compound (F) is 0.01~30. A surface treatment method for galvanized steel sheets, which is coated on a surface of a galvanized steel sheet with a surface treatment agent for galvanized steel sheets according to any one of claims 1 to 7 and heated and dried on the surface of the galvanized steel sheet A film having a film amount of 25 to 1000 mg/m ² is formed thereon. A galvanized steel sheet having a film obtained by a surface treatment method of a galvanized steel sheet according to item 8 of the patent application.