JP2004232083A - Inorganic/organic-composite-treated galvanized steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic/organic-composite-treated galvanized steel sheet which has a treated film not containing chromium and is excellent in corrosion resistance, coating film adhesiveness, and electrophoretic coatability after alkali degreasing. <P>SOLUTION: The inorganic/organic-composite-treated galvanized steel sheet comprises a galvanized steel sheet, a zinc phosphate treatment film formed on the surface of the galvanized steel sheet and having a film weight of 0.3-5 g/m<SP>2</SP>, and a post-treatment film having a film weight of 0.01-1 g/m<SP>2</SP>and formed on the zinc phosphate treatment film by using a post-treatment agent containing (A) at least one compound selected from the group consisting of thiocarbonyl group-containing compounds, sulfide group-containing compounds, and guanidyl group-containing compounds, (B) a zirconium compound, (C) a cross-linking agent, and (D) an inorganic rust-preventive agent. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

The present invention relates to an inorganic-organic composite treated zinc-based plated steel sheet.

Conventionally, a zinc-based plated steel sheet used for applications such as automobiles, home appliances, and building materials has been generally subjected to a phosphate treatment or a chromate treatment for the purpose of improving corrosion resistance and coating film adhesion. In particular, a method of performing a sealing treatment with chromate after a zinc phosphate treatment has been widely practiced because of its great effect in improving corrosion resistance and paint adhesion. However, in recent years, against the background of increasing environmental problems, it has been desired to develop a surface treatment technique that does not use highly toxic chromate, and the following techniques have been proposed.

On the surface of the galvanized steel sheet, as a first layer, a zinc phosphate treated coating layer containing at least one selected from nickel, manganese and magnesium and having an adhesion amount of 0.2 to 2.5 g / m ² is provided. And a zinc phosphate composite treated steel sheet having an organic coating mainly composed of at least one organic resin selected from an ethylene-based resin, an epoxy-based resin, a urethane-based resin, and an acrylic resin as a second layer thereon. Is disclosed (for example, refer to Patent Document 1).

The surface of the steel sheet, zinc-based plating coating, 0.3 g / ^{m 2} or more zinc phosphate coating, and organic coating of 0.3 to 2 g / ^{m 2} are sequentially formed, zinc film phosphate containing Mg Also disclosed is an organic composite zinc-based plated steel sheet in which Mg / P (mass ratio) in a zinc phosphate-treated film is 0.15 or more and Mg amount is 20 mg / m ² or more (for example, see Patent Document 2). .).

The galvanized steel sheet subjected to such treatment is usually used as it is or after being subjected to press forming and alkali degreasing and washing. In particular, for automotive applications, a car body using a zinc-coated steel sheet that has been treated as described above is placed on a painting line, and alkali degreasing, zinc phosphate treatment, electrodeposition coating, intermediate coating, and top coating are sequentially applied. Is done. For this reason, the film formed on the zinc-based plated steel sheet is required to be a tough film that does not dissolve or deteriorate even when contacted with an alkali degreasing solution or a zinc phosphate treatment solution.

However, the zinc phosphate composite-treated coated steel sheet and the organic composite zinc-based plated steel sheet obtained by the above-described method and the like are subjected to alkali degreasing after forming, because the coating is dissolved or deteriorated. Is inferior in corrosion resistance and poor in coating film adhesion.

JP 2001-105528 A (page 2) JP 2001-131763 A (page 2)

The present invention has been made in view of the above-mentioned circumstances, and provides an inorganic-organic composite-treated galvanized steel sheet that does not contain harmful chromate in a treated film and has excellent corrosion resistance and film adhesion after alkaline degreasing. It is intended for that purpose.

The present invention, on the surface of the galvanized steel sheet, coating amount has a zinc phosphate coating of 0.3 to 5 g / ^{m 2,} on which, coating amount of 0.01 to 1 g / ^{m 2,} At least one compound (A) selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound, an organic resin (B), a crosslinking agent (C), and an inorganic rust inhibitor ( An inorganic-organic composite-treated galvanized steel sheet having a post-treatment film containing D).

The zinc phosphate treated film contains magnesium, and the magnesium phosphate content (mass ratio) in the zinc phosphate treated film is 0.1 or more, and the magnesium content is 20 mg / m ² or more. Preferably, there is.

The post-treatment film comprises 0.1 to 10% by mass of at least one compound (A) selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound, and 40 to 80% by mass. Of the organic resin (B), 5 to 30% by mass of the crosslinking agent (C), and 10 to 40% by mass of the inorganic rust inhibitor (D).

The organic resin (B) includes a neutralized product of an ethylene-unsaturated carboxylic acid copolymer (B1) and at least one resin (B2) selected from an acrylic resin, a polyester resin, a polyurethane resin, and an epoxy resin. Wherein the neutralized product (B1) has a neutralization ratio of 30 to 90% with an alkali metal, and the resin (B2) is at least one selected from the group consisting of a carboxyl group, a hydroxyl group and an amide group. The weight ratio of the neutralized product (B1) to the resin (B2) is preferably 100: 0 to 20:80.

The crosslinking agent (C) is preferably at least one selected from the group consisting of epoxy compounds, silane compounds, organic titanium compounds, amino resins, blocked isocyanates and carbodiimide compounds.

The inorganic rust preventive (D) is preferably at least one selected from the group consisting of silica particles, a phosphate compound and a niobium compound.
Hereinafter, the present invention will be described in detail.

The inorganic-organic composite-treated zinc-coated steel sheet of the present invention has a zinc phosphate-coated film on the surface of a zinc-based plated steel sheet, and further has a post-treatment film thereon. Has improved corrosion resistance and coating film adhesion after alkali degreasing.

The zinc-plated steel sheet treated with an inorganic-organic composite according to the present invention is obtained by forming a zinc phosphate treatment film as a first film on the surface of a zinc-plated steel sheet. Thereby, a certain degree of corrosion resistance, coating film adhesion, and lubricity can be imparted to the galvanized steel sheet.

The zinc phosphate treatment film can be formed by a conventionally known zinc phosphate treatment agent containing phosphate ions and zinc ions.
The source of the zinc ion is not particularly limited as long as it is a compound containing zinc, and examples thereof include zinc, zinc oxide, zinc carbonate, and zinc nitrate.
The source of the phosphate ion is not particularly limited as long as it is a compound containing phosphoric acid, and examples thereof include phosphoric acid, phosphorus pentoxide, and sodium dihydrogen phosphate. Further, other components used in the zinc phosphate treating agent may be appropriately contained.

The zinc phosphate treated film preferably contains magnesium. Thereby, the corrosion resistance of the galvanized steel sheet can be further improved, and the adhesion with the post-treatment film can be improved.

When the zinc phosphate treated film contains magnesium, the zinc phosphate treated film has a magnesium / phosphorus (mass ratio of magnesium to phosphorus in the film) of 0.1 or more in the film. Is preferred. If it is less than 0.1, the corrosion resistance may not be improved by the addition. More preferably, it is 0.15 to 0.5.

When the zinc phosphate treated film contains magnesium, the zinc phosphate treated film preferably has a magnesium content in the film of 20 mg / m ² or more. If it is less than 20 mg / m ² , there is a possibility that the corrosion resistance may not be improved. More preferably 30 to 70 mg / ^{m 2.}

The zinc phosphate coating, the lower limit 0.3 g / ^{m 2,} and is formed with a film of upper 5 g / ^{m 2.} If it is less than 0.3 g / m ² , corrosion resistance may be insufficient, and if it exceeds 5 g / m ² , peeling of the film may occur when severe processing is performed. The lower limit is more preferably 0.5 g / m ² , and the upper limit is more preferably 2.5 g / m ² .

As the treatment liquid for forming the zinc phosphate treatment film, a commercially available treatment containing phosphate ions and zinc ions as main components and further adding metal ions other than zinc, nitrate ions and fluoride ions as necessary. Liquid can be used. When magnesium is contained in the zinc phosphate treated film, a bath in which magnesium nitrate is added to the above zinc phosphate treated solution is preferably used. The amount of magnesium and the magnesium / phosphorus ratio in the coating can be controlled by the amount of magnesium nitrate added.

As a method for treating the zinc-based plated steel sheet with the zinc phosphate treating agent, the zinc phosphate treated film can be formed by any of a reactive treatment and a coating treatment. As the reaction type treatment, for example, after performing degreasing, washing with water, and surface conditioning on a zinc-based plated steel sheet, contacting with the above zinc phosphate treatment liquid, washing with water, and drying to form a zinc phosphate treatment film. Can be. The amount of the zinc phosphate treatment film can be adjusted by, for example, changing the treatment time or the concentration of the treatment agent.

As the coating type treatment, for example, a zinc-coated steel sheet is coated with the above-mentioned zinc phosphate treatment solution in an amount corresponding to the required film amount by a roll coating method, and is also applied by a dipping method or a spray method, and then a roll drawing method. There is also a method of adjusting to a necessary application amount by the following method. After the zinc phosphate treating agent is applied to the galvanized steel sheet, it is dried using a drying furnace or the like to form a zinc phosphate treated film.

The inorganic-organic composite treated zinc-based plated steel sheet of the present invention is selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound as a second film on the zinc phosphate-treated film. A post-treatment film containing at least one compound (A), an organic resin (B), a crosslinking agent (C), and an inorganic rust preventive (D) is formed. By forming a post-treatment film on the zinc phosphate treatment film, the corrosion resistance after alkali degreasing and the adhesion of the coating film can be improved.

That is, in the galvanized steel sheet on which only the zinc phosphate treatment film is formed, there may be a portion where the dense zinc phosphate treatment film is not formed on the surface of the steel sheet, and this causes corrosion resistance. May be inferior. Also, when coating on a zinc-based plated steel sheet on which only an inorganic coating such as zinc phosphate is formed, the adhesion of the coating film is not sufficient for the adhesion test performed after bending or water resistance test. There is. On the other hand, the inorganic-organic composite treated zinc-based plated steel sheet of the present invention, on the zinc phosphate treated film, further, at least selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound and a guanidyl group-containing compound. A post-treatment film containing one compound (A), an organic resin (B), a cross-linking agent (C), and an inorganic rust preventive (D) is formed. The entire surface of the steel sheet including the part where the treatment film is not formed is covered with a uniform and tough film. Therefore, the zinc-plated steel sheet treated with the inorganic-organic composite treatment of the present invention is characterized in that, when the zinc-coated steel sheet is further formed and subjected to alkali degreasing treatment, the formed post-treatment film is deteriorated or dissolved by the degreasing treatment. As a result, excellent post-degreased corrosion resistance and coating film adhesion can be obtained.

The post-treatment film includes at least one compound (A) selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound, an organic resin (B), a crosslinking agent (C), and And a post-treatment agent containing an inorganic rust preventive (D).

The thiocarbonyl group-containing compound, the sulfide group-containing compound, and the guanidyl group-containing compound have high affinity for zinc ions, and thus are effective in preventing white rust on galvanized steel sheets.

The thiocarbonyl group-containing compound is preferably represented by the following general formula (1). Thereby, the corrosion resistance of the galvanized steel sheet can be further improved.

Wherein, X, Y are the same or different, H, OH, or represents SH or NH _2, or, OH as a substituent, may have an SH or NH _2, and, -O-, Represents a hydrocarbon group having 1 to 15 carbon atoms which may contain -NH-, -S-, -CO- or -CS-, and X and Y may combine to form a ring.

The thiocarbonyl group-containing compound represented by the general formula (1) refers to a thiocarbonyl group represented by the following formula (I)

Wherein a thiocarbonyl group having a nitrogen atom or an oxygen atom represented by the following formula (II) is preferable.

Further, a compound capable of forming a thiocarbonyl group-containing compound in an aqueous solution or under conditions in the presence of an acid or an alkali can also be used.
Examples of the thiocarbonyl group-containing compound include the following formula (III)

And derivatives thereof, for example, methylthiourea, dimethylthiourea, trimethylthiourea, ethylthiourea, diethylthiourea, 1,3-dibutylthiourea, phenylthiourea, diphenylthiourea, 1,3-bis (dimethylamino Propyl) -2-thiourea, ethylenethiourea, propylenethiourea, thiopental, thiocarbazide, thiocarbazones, thiocyanuric acids, thiohydantoin, 2-thiouramil, 3-thiourazole, the following formula (IV)

And a derivative thereof, for example, thioformamide, thioacetamide, thiopropionamide, thiobenzamide, thiocarbostyril, thiosaccharin, and the following formula (V)

A thioaldehyde compound represented by, for example, thioformaldehyde, thioacetaldehyde, the following formula (VI)

Carbothioic acids and salts thereof represented by, for example, thioacetic acid, thiobenzoic acid, dithioacetic acid, sodium methyldithiocarbamate, sodium dimethyldithiocarbamate, triethylamine dimethyldithiocarbamate, sodium diethyldithiocarbamate, pentamethylenedithiocarbamate piperidine Salt, pipecoline dithiocarbamate pipecoline salt, potassium o-ethylxanthate, the following formula (VII)

And thiocarbonates, for example, ethylene tridithiocarbonate, and other compounds having the structure of the above formula (I), for example, thiocoumazone, thiocumothiazone, thionin blue J, thiopyrone, thiopyrine, thiobenzophenone and the like. These thiocarbonyl group-containing compounds may be used alone or in combination of two or more. Among the thiocarbonyl group-containing compounds, those that do not dissolve in water are once dissolved in an alkaline solution and then blended in a post-treatment agent.

The thiocarbonyl group-containing compound is preferably a polymer having a side chain represented by the following general formula (2) and having a weight average molecular weight of 1,000,000 or less. When such a polymer is used, the corrosion resistance of the zinc-based plated steel sheet can be further improved.

Z is _{- (CH} 2) represents a COO-A, a is an integer from 1 to 8, A represents ammonia, an amine or a monovalent metal ion.

The polymer having a side chain represented by the general formula (2) is not particularly limited, and examples thereof include a polymer represented by the following general formula (3).

m and n are integers at which the weight average molecular weight of the polymer becomes 1,000,000. n / n + m is 0.2 to 0.8, preferably 0.3 to 0.6. If it is less than 0.2, the water solubility of the polymer decreases, while if it exceeds 0.8, the corrosion resistance decreases. A may be the same or different. B and C represent a main chain of the polymer, and examples thereof include those represented by the following general formula (4). Unless otherwise indicated in the following general formula (4), the position where the side chain is bonded indicates that the side chain may be bonded to any carbon atom. B and C may be the same or different.

p, q, and r are not particularly limited as long as the weight average molecular weight of the polymer is an integer of 1,000,000 or less.

The thiocarbonyl group-containing compound is preferably a polymer having a side chain represented by the general formula (2) and having a weight average molecular weight of 1,000,000 or less. If it exceeds 1,000,000, the viscosity becomes high and a uniform film may not be easily obtained.

The sulfide group-containing compound has the same effect as the thiocarbonyl group-containing compound, and can provide excellent corrosion resistance in a thin film by being contained in a post-treatment film.

The sulfide group-containing compound is not particularly limited as long as it is a compound containing a sulfide group, but is preferably a hydroxyl group-containing sulfide compound from the viewpoint of corrosion resistance.

The hydroxyl group-containing sulfide compound is not particularly limited as long as it is a compound containing a hydroxyl group and a sulfide group. For example, 1,2-bis (2-hydroxyethylthio) ethane, 1,4-bis (2-hydroxyethyl Thio) butane, 1,3-bis (2-hydroxyethylthio) -2-propanol, 3- (2-aminophenylthio) -1,2-propanediol, (2,3-dihydroxypropylthio) -2- Sodium methyl-propanesulfonate, sodium (2,3-dihydroxypropylthio) -propanesulfonate, 3- (2-hydroxyethylthio) -2-hydroxypropylmercaptan, 3- (2-aminophenylthio) -2- Hydroxypropyl mercaptan and the like can be mentioned.

The guanidyl group-containing compound has the same effect as the thiocarbonyl group-containing compound, and can provide excellent corrosion resistance in a thin film by being contained in a post-treatment film.

The guanidyl group-containing compound is not particularly limited as long as it is a compound containing a guanidyl group, but is preferably a compound represented by the following formula (5). Thereby, the corrosion resistance of the galvanized steel sheet can be further improved.

In the formula, X ′ and Y ′ are the same or different and represent H, NH ₂ , a phenyl group or a methylphenyl group (tolyl group), or H, NH ₂ , a phenyl group or a methylphenyl group as a substituent. (Tolyl group) and may include -C (= NH)-, -CO- or -CS-.

Examples of the guanidyl group-containing compound include guanidine, aminoguanidine, guanylthiourea, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, 1,3-diphenylguanidine and the like.
The above guanidyl group-containing compounds may be used alone or in combination of two or more.

The content of at least one compound (A) selected from the group consisting of the thiocarbonyl group-containing compound, the sulfide group-containing compound, and the guanidyl group-containing compound (the thiocarbonyl group-containing compound, the sulfide group-containing compound in the post-treatment film) And the total amount of the guanidyl group-containing compound) are preferably 0.1% by mass as the lower limit and 10% by mass as the upper limit. If it is less than 0.1% by mass, the corrosion resistance of the thin film may not be sufficient, and if it exceeds 10% by mass, the adhesion of the coating film may be reduced. The lower limit is more preferably 0.2% by mass, and the upper limit is more preferably 5% by mass.

Since a uniform post-treatment film can be formed by including the organic resin (B) in the post-treatment film, it is selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound. The at least one compound (A) and the inorganic rust inhibitor (D) can be suitably fixed in the film, and the adhesion of the overcoat film can be improved.

The organic resin (B) is not particularly limited, and for example, an acrylic resin, a vinyl resin, a polyester resin, a polyurethane resin, an epoxy resin, or the like can be used. And at least one compound (A) selected from the group consisting of the above-mentioned thiocarbonyl group-containing compound, sulfide group-containing compound and guanidyl group-containing compound, and an inorganic rust preventive (D) described later in the film. It is preferable to contain a neutralized product (B1) of an ethylene-unsaturated carboxylic acid copolymer as an essential component because it can be suitably fixed.

The ethylene-unsaturated carboxylic acid copolymer is a copolymer obtained by radically polymerizing ethylene and an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid under high temperature and high pressure. It is.

The neutralized product of the above-mentioned ethylene-unsaturated carboxylic acid copolymer (B1) means that a part of the carboxyl groups contained in the ethylene-unsaturated carboxylic acid copolymer is neutralized by a basic compound. .

The neutralized product (B1) of the ethylene-unsaturated carboxylic acid copolymer has a neutralization ratio of 30 to 90% with an alkali metal, and is partially neutralized with ammonia and an organic amine together with the alkali metal. It may be. That is, 30 to 90% of the carboxyl groups contained in the ethylene-unsaturated carboxylic acid copolymer are neutralized by an alkali metal supplied by a basic alkali metal compound such as NaOH, KOH, RbOH, CsOH, etc. , Means that some or all of the carboxyl groups present without being neutralized by an alkali metal are neutralized with ammonia or an organic amine.

Examples of the organic amine include triethylamine and ethanolamine. The above ammonia and organic amine may be used alone or in combination of two or more.

When the neutralization ratio of the above-mentioned alkali metal compound is less than 30%, the toughness of the film of the neutralized product of the ethylene-unsaturated carboxylic acid copolymer (B1) may be reduced and the corrosion resistance may be insufficient. On the other hand, if it exceeds 90%, the water resistance of the film may be reduced and the corrosion resistance may be insufficient.

When the organic resin (B) contains the neutralized product of the ethylene-unsaturated carboxylic acid copolymer (B1), the neutralized product of the ethylene-unsaturated carboxylic acid copolymer (B1) is modified. It may be made to be.

Examples of the organic resin (B) include acrylic resins, polyester resins, polyurethane resins, and epoxy resins, in addition to the neutralized product of the ethylene-unsaturated carboxylic acid copolymer (B1). When at least one resin (B2) selected from the group consisting of an acrylic resin, a polyester resin, a polyurethane resin, and an epoxy resin is used as the organic resin (B), the resin (B2) contains a carboxyl group, a hydroxyl group, And at least one functional group selected from the group consisting of amide groups. Thereby, the resin (B2) reacts with the crosslinking agent (C) to form a tough film. The combined use of the neutralized product of the ethylene-unsaturated carboxylic acid copolymer (B1) and the resin (B2) can further improve the coating film adhesion.

When the neutralized product (B1) and the resin (B2) are contained as the organic resin (B), the mass ratio (B1: B2) between the neutralized product (B1) and the resin (B2) Is preferably from 100: 0 to 20:80. When the neutralized product (B1) is less than 20% by mass relative to 100% by mass of the total amount of B1) and B2, a tough film may not be formed. More preferably, it is 100: 0 to 30:70.

The content of the organic resin (B) is preferably 40% by mass as the lower limit and 80% by mass as the upper limit in the post-treatment film. If the amount is less than 40% by mass, a tough coating film may not be formed, and the adhesion of the coating film may be reduced. If it exceeds 80% by mass, the corrosion resistance after alkaline degreasing may be reduced. The lower limit is more preferably 50% by mass, and the upper limit is more preferably 75% by mass.

By including the crosslinking agent (C) in the post-treatment agent, the crosslinking agent (C) reacts with a functional group such as a carboxyl group or a hydroxyl group in the organic resin (B) to be crosslinked, and the alkali resistance of the film is reduced. And solvent resistance can be improved.

The crosslinking agent (C) is not particularly limited as long as it is a compound having a plurality of reactive functional groups. However, from the viewpoint that a tough film can be formed, and the alkali resistance and solvent resistance of the film are improved, It is preferably at least one selected from the group consisting of epoxy compounds, silane compounds, organic titanium compounds, amino resins, blocked isocyanate compounds and carbodiimide compounds.

The epoxy compound is not particularly limited as long as it has a plurality of oxirane rings.For example, glycidyl adipate, glycidyl phthalate, glycidyl terephthalate, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol Polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylpropane polyglycidyl ether, neopentyl glycol glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylenelen Glycol diglycidyl ether, polypropylenelen glycol diglycidyl ether 2,2-bis- (4'-glycidyloxyphenyl) propane, triglycidyltris (2-hydroxyethyl) isocyanurate, tris (2,3-epoxypropyl) isocyanurate, bisphenol A diglycidyl ether, hydrogenated bisphenol A Glycidyl group-containing compounds such as diglycidyl ether can be exemplified. These may be used alone or in combination of two or more.

The silane compound is not particularly limited as long as it is a silane compound having a plurality of reactive functional groups, for example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylethoxysilane, N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ -Methacryloxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri Toxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane , N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like. The silane compound includes a silane hydrolyzate. These may be used alone or in combination of two or more.

The organic titanium compound is not particularly limited as long as it is an organic compound containing titanium. For example, dipropoxy bis (triethanol aminato) titanium, dipropoxy bis (diethanol aminato) titanium, dibutoxy bis (triethanol aminato) ) Titanium, dibutoxy bis (diethanol aminato) titanium, dipropoxy bis (acetylacetonato) titanium, dibutoxy bis (acetyl acetonato) titanium, dihydroxy bis (lactato) titanium monoammonium salt, dihydroxy bis (lactato) titanium Diammonium salts, propanedioxytitanium bis (ethylacetoacetate), oxotitanium bis (monoammonium oxalate), isopropyltri (N-amidoethylaminoethyl) titanate and the like can be mentioned. Kill. These may be used alone or in combination of two or more.

The amino resin is not particularly limited, for example, methylolated amino obtained by the reaction of an amino component such as melamine, urea, benzoquanamine, acetogranamine, sterogtanamine, sprogamine and formaldehyde, paraformaldehyde, trioxane and the like. Resins and the like can be mentioned. The methylol group of the methylolated amino resin may be alkyl etherified. These may be used alone or in combination of two or more.

The blocked isocyanate compound is not particularly limited, and examples thereof include compounds in which an isocyanate group of an aliphatic, alicyclic, or aromatic polyisocyanate compound is blocked with a compound having active hydrogen. Examples of the compound having active hydrogen include phenol-based, alcohol-based, active methylene-based, oxime-based, and nitrite-based compounds.

The carbodiimide compound is not particularly limited, and includes, for example, those obtained by a decarboxylation condensation reaction of an aliphatic diisocyanate.

The content of the crosslinking agent (C) in the post-treatment film is preferably 5% by mass as the lower limit and 30% by mass as the upper limit. When the amount is less than 5% by mass, the crosslinking of the organic resin (B) becomes insufficient, and the alkali resistance and the solvent resistance of the film may be deteriorated. There is a possibility that the toughness is reduced and the corrosion resistance and the coating film adhesion are reduced.

By including the inorganic rust preventive (D) in the post-treatment film, a stable metal corrosion product can be generated in a corrosive environment, the progress of corrosion can be suppressed, and excellent corrosion resistance can be imparted. Can be.

The inorganic rust preventive (D) is not particularly limited as long as it is an inorganic compound having a rust preventive action, but is preferably a silica particle, a phosphoric acid compound, or a niobium compound from the viewpoint of further suppressing corrosion.

The silica particles are not particularly limited, but are preferably fine silica particles such as colloidal silica, fumed silica, and ion-exchange silica having a primary particle diameter of 5 to 50 nm because the post-treatment film is a thin film. Commercially available products include, for example, Snowtex O, Snowtex N, Snowtex C, Snowtex IPA-ST (Nissan Chemical Industries), Adelite AT-20N, AT-20A (Asahi Denka Kogyo), Aerosil 200 (Nippon Aerosil) And the like.

The phosphoric acid compound is not particularly limited as long as it is a compound containing phosphorus. For example, phosphoric acids such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid; aminotri (methylenephosphonic acid); Examples thereof include phosphonic acids such as 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid); organic phosphoric acids such as phytic acid and salts thereof. These may be used alone or in combination of two or more.

The niobium compound is not particularly limited as long as it is a compound containing niobium, and examples thereof include niobium oxide, niobic acid and salts thereof, fluoroniobate, and fluorooxoniobate. These may be used alone or in combination of two or more.

The content of the inorganic rust preventive (D) is preferably 10% by mass at the lower limit and 40% by mass at the upper limit in the post-treatment film. If it is less than 10% by mass, it may not be possible to suppress the progress of corrosion. If it exceeds 40% by mass, the adhesion of the coating film may be reduced. The lower limit is more preferably 15% by mass, and the upper limit is more preferably 35% by mass.

The post-treatment film may further include other additives such as a pigment, a dye, a surfactant, and a lubricant. As the pigment, for example, inorganic pigments such as zinc oxide (ZnO) and carbon black, and organic coloring pigments can be used. Examples of the surfactant include a nonionic surfactant and an anionic surfactant. As the lubricant, for example, polyethylene wax, modified polyethylene wax, ethylene tetrafluoride resin and the like can be used.

The post-treatment film has a lower limit of 0.01 g / m ² and an upper limit of 1 g / m ² . If the amount is less than 0.01 g / m ² , there is a possibility that the corrosion resistance and coating film adhesion after alkali degreasing may not be improved. If the amount is more than 1 g / m ² , the conductivity decreases, and the weldability and the electrodeposition coating are reduced. May be affected. The lower limit is more preferably 0.03 g / m ² , and the upper limit is more preferably 0.7 g / m ² .

The post-treatment film can be formed by applying the above-mentioned post-treatment agent to the zinc-based plated steel sheet on which the zinc phosphate treatment film is formed. The application method is not particularly limited, and examples thereof include roll coating, air spray, airless spray, and immersion. In order to enhance the curability of the film formed by the post-treatment agent, it is preferable to heat the object to be coated in advance or to heat and dry the object to be coated after coating. The heating temperature of the object to be coated is preferably in a range of a lower limit of 50 ° C. and an upper limit of 250 ° C. in the reached plate temperature. The lower limit is preferably 70 ° C., and the upper limit is preferably 200 ° C. If the heating temperature is lower than 50 ° C., the evaporation rate of water is slow and sufficient film formability cannot be obtained, so that the solvent resistance and the alkali resistance decrease. On the other hand, when the temperature exceeds 250 ° C., thermal decomposition of the resin occurs, and the solvent resistance and the alkali resistance decrease.

The zinc-based plated steel sheet used for the inorganic-organic composite treated zinc-based plated steel sheet of the present invention is not particularly limited, and examples thereof include a galvanized steel sheet, a zinc-nickel plated steel sheet, a zinc-iron plated steel sheet, a zinc-chrome plated steel sheet, Examples include zinc-based electroplated steel sheets such as zinc-manganese-plated steel sheets, zinc-aluminum-plated steel sheets, and zinc-magnesium-plated steel sheets;

The zinc-plated steel sheet treated with an inorganic-organic composite according to the present invention has a zinc phosphate treated film formed on the surface of a zinc-based plated steel sheet at a coating amount of 0.3 to 5 g / m ² , and a thiocarbonyl group At least one compound (A) selected from the group consisting of a compound containing a sulfide group and a compound containing a guanidyl group, an organic resin (B), a crosslinking agent (C), and an inorganic rust inhibitor (D). Since it is obtained by forming the contained post-treatment film at a film amount of 0.01 to 1 g / m ² , the entire surface of the steel sheet can be covered with a uniform and tough film. Accordingly, when the inorganic-organic composite-treated zinc-coated steel sheet of the present invention is further formed and subjected to alkali degreasing treatment, the post-treatment film formed on the inorganic-organic composite-treated zinc-coated plated steel sheet by the degreasing treatment is deteriorated. Dripping and dissolution can be suppressed. Therefore, the inorganic-organic composite treated zinc-based plated steel sheet of the present invention has excellent corrosion resistance after alkaline degreasing and coating film adhesion.

Since the inorganic-organic composite-treated zinc-coated steel sheet of the present invention has the above-described configuration, it is possible to obtain a zinc-coated steel sheet excellent in various properties such as corrosion resistance and paint adhesion after alkali degreasing without the need for chromate. it can. Furthermore, the inorganic-organic composite treated zinc-based plated steel sheet has a simple manufacturing method and is excellent in cost, and can be suitably used for various applications such as automobiles, home appliances, and building materials.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by mass” unless otherwise specified.

(Method of processing galvanized steel sheet)
Using the plating original plate shown in Table 1, after alkali degreasing treatment, zinc phosphate treatment and post treatment were sequentially performed to prepare a test plate.
The zinc phosphate treatment is carried out at a temperature of 45 ° C. for a treatment time of 1 to 10 seconds by a spray method using a bath prepared as shown in Table 2 after a commercially available TiO ₂ colloid-based surface conditioning treatment. , Washed with water and dried.
In the post-treatment, an aqueous treatment agent containing 10 parts by mass of the components shown in Table 3 was applied using a roll coater.

Examples 1 to 8 and Comparative Examples 1 to 5
Test plates were manufactured under the conditions shown in Table 4 (type of original plate, treatment bath for zinc phosphate treatment, amount of zinc phosphate-treated film, amount of post-treatment agent, amount of post-treated film). EG20 or GI70 in Table 1 was used as an original plate, and No. 1 in Table 2 was used as a zinc phosphate treatment bath. Nos. 1 to 3 were used (Comparative Example 1 was not treated with zinc phosphate). 1-8 were used. The amount of the film after the zinc phosphate treatment was calculated by dissolving the zinc phosphate-treated film with chromic acid and calculating the difference in mass before and after the treatment. Each of the post-treatment agents was applied to the sample after the zinc phosphate treatment, dried at a reached plate temperature of 80 ° C., allowed to stand, and cooled. The amount of the post-treated film was calculated from the difference in mass before and after the application.

(Performance evaluation method)
Corrosion resistance The edge and the back of the sample were tape-sealed, and an SST (JIS-Z-2371) test was performed. The occurrence of white rust after 72 hours was observed. The evaluation criteria were as follows.
〇; no white rust generated △; less than 10% white rust ×; more than 10% white rust

Corrosion resistance after degreasing The edge and the back of the sample are tape-sealed, degreased with a commercially available alkaline degreasing solution (pH = 12.5, 40 ° C, immersion for 1 minute), and then subjected to SST (JIS-Z-2371) test. Was done. The occurrence of white rust after 72 hours was observed. The evaluation criteria were as follows.
〇; no white rust generated △; less than 10% white rust ×; more than 10% white rust

Paint adhesion After the sample was degreased with a commercially available alkaline degreasing solution (pH = 10.5, immersed at 40 ° C. for 1 minute), the melamine alkyd paint (Nippon Paint Co., Ltd., Super Rack 100) was dried. Was baked at 120 ° C. for 25 minutes. After standing all day and night, it was immersed in boiling water for 30 minutes, taken out and left to stand for 1 day, then cut at 1 mm intervals, cut it out with Ericksen 7 mm, and peeled off with a tape. The evaluation criteria were as follows.
〇; no peeling △; peeling around cut flaws x; peeling or more The evaluation results are shown in Table 4.

Examples 9 to 14 and Comparative Examples 6 to 8
The conditions shown in Table 5 (type of original plate, treatment bath for zinc phosphate treatment, amount of zinc phosphate treated film, magnesium / phosphorus mass ratio, amount of magnesium, post-treatment agent, amount of post-treated film) A test plate was manufactured as described above. EG30 or GI70 in Table 1 was used as an original plate, and No. 1 in Table 2 was used as a zinc phosphate treatment bath. No. 3 and No. 4 in Table 3 were used as post-treatment agents. 1, 3, 5, 6, 7, 8 were used. The amount and composition of the zinc phosphate treated film were determined by dissolving the zinc phosphate treated film with chromic acid and quantifying and calculating by ICP analysis. Each of the post-treatment agents was applied to the sample after the zinc phosphate treatment, dried at a plate temperature of 150 ° C., cooled with water, and left to dry. The amount of the post-treated film was calculated from the difference in mass before and after the application.

(Performance evaluation method)
Corrosion resistance The edge and the back of the sample were tape-sealed, and cross-cut flaws (flaws reaching the base steel) were made with a cutter, and a CCT test was performed. The state of occurrence of red rust after 15 cycles was observed.
[CCT test conditions]
Salt spray (5% NaCl, 35 ° C) 6 hours → dry (50 ° C, 45% RH) 3 hours → wet (50 ° C, 95% RH) 14 hours → dry (50 ° C, 45% RH) 1 hour One cycle was repeated.
The evaluation criteria were as follows.
〇; no red rust occurred; 赤 red rust occurred near flaws ×; red rust occurred over the entire surface

Corrosion resistance after degreasing The edge and the back of the sample are tape-sealed, cross-cut flaws (flaws reaching the ground iron) are made with a cutter, and a commercially available alkaline degreasing solution (pH = 12.5, 40 ° C, 1 minute) Immersion), and then a CCT test was performed. The state of occurrence of red rust after 15 cycles was observed. CCT test conditions were the same as in the evaluation of corrosion resistance. The evaluation criteria were as follows.
〇; no red rust occurred; 赤 red rust occurred near flaws ×; red rust occurred over the entire surface

Paint adhesion After the sample was subjected to a commercial alkaline degreasing solution (pH = 10.5, immersed in 40 ° C for 1 minute) and a chemical conversion treatment for automobiles (Surfdine 2500MZL manufactured by Nippon Paint Co., Ltd.), the cations for automobiles were used. Electrodeposition coating (V20, 20 μm, Nippon Paint Co., 170 ° C., baking for 20 minutes) was performed. After standing all day and night, it was immersed in warm water at 50 ° C., taken out after 10 days, cut in squares at 2 mm intervals, extruded by Erichsen 7 mm, and peeled off with a tape. The evaluation criteria were as follows.
〇; no peeling △; peeling around cut flaws x; peeling or more The evaluation results are shown in Table 5.

EG20, zinc phosphate treatment bath No. The test plates using Examples 1 and 2 (Examples 1 to 6 and 8) were excellent in each performance. Even when EG30 is used, the zinc phosphate treatment bath No. When using Nos. 3 and 4 (Examples 9 to 11, 13, and 14), it was possible to obtain products excellent in each performance. Furthermore, when GI70 was used (Examples 7 and 12), those excellent in each performance could be obtained. On the other hand, in the test plate obtained in the comparative example, it was not possible to obtain a test plate in which all of the performances were excellent.

INDUSTRIAL APPLICABILITY The inorganic-organic composite treated zinc-based plated steel sheet of the present invention has excellent corrosion resistance and coating film adhesion after alkali degreasing, and thus can be used for applications such as automobiles, home appliances, and building materials.

Claims (6)

On the surface of the galvanized steel sheet, coating amount has a zinc phosphate coating of 0.3 to 5 g / ^{m 2,} on which, coating amount of 0.01 to 1 g / ^{m 2,} containing a thiocarbonyl group Contains at least one compound (A) selected from the group consisting of compounds, sulfide group-containing compounds and guanidyl group-containing compounds, an organic resin (B), a crosslinking agent (C), and an inorganic rust inhibitor (D) An inorganic-organic composite treated zinc-based plated steel sheet having a post-treatment film to be treated. The zinc phosphate treatment film contains magnesium,
The magnesium zinc phosphate coating in / phosphorus (mass ratio) is 0.1 or more, and inorganic claim 1, wherein the magnesium content is 20 mg / m ² or more - organic composite-treated zinc-plated steel sheet. The post-treatment film comprises 0.1 to 10% by mass of at least one compound (A) selected from the group consisting of a thiocarbonyl group-containing compound, a sulfide group-containing compound, and a guanidyl group-containing compound, and 40 to 80% by mass. The inorganic-organic composite treated zinc according to claim 1 or 2, comprising a composition of an organic resin (B), 5 to 30% by mass of a crosslinking agent (C), and 10 to 40% by mass of an inorganic rust preventive (D). System plated steel sheet. The organic resin (B) comprises a neutralized product of an ethylene-unsaturated carboxylic acid copolymer (B1) and at least one resin (B2) selected from an acrylic resin, a polyester resin, a polyurethane resin and an epoxy resin. Become
The neutralized product (B1) has a neutralization rate of 30 to 90% with an alkali metal,
The resin (B2) has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and an amide group;
The mass ratio between the neutralized product (B1) and the resin (B2) is 100: 0 to 20:80.
The zinc-plated steel sheet according to claim 1, 2 or 3. 5. The inorganic material according to claim 1, wherein the crosslinking agent (C) is at least one selected from the group consisting of an epoxy compound, a silane compound, an organic titanium compound, an amino resin, a blocked isocyanate compound and a carbodiimide compound. -Organic composite treated galvanized steel sheet. The inorganic-organic composite treated zinc system according to claim 1, 2, 3, 4, or 5, wherein the inorganic rust preventive (D) is at least one selected from the group consisting of silica particles, a phosphoric acid compound, and a niobium compound. Plated steel sheet.