JP2001105528A - Zinc phosphate composite treated steel panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environmentally harmonic type zinc phosphate composite treated steel panel excellent in corrosion resistance, powdering resistance, lubricating properties and paint adhesion and containing no chromium. SOLUTION: A zinc phosphate composite treated steel panel excellent in corrosion resistance powdering resistance, lubricating properties and paint adhesion is constituted by providing a zinc phosphate film layer containing at least one element selected from nickel, manganese and magnesium on the surface of a galvanized steel panel in an adhesion amount of 0.2-2.5 g/m2 as a first layer and providing an organic film based on at least one organic resin selected from an ethylenic resin, an epoxy resin, a urethane resin and an acrylic resin on the surface of the zinc phosphate film layer as a second layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc phosphate treated steel sheet based on a galvanized steel sheet used for automobile bodies and home electric appliances, etc., which has corrosion resistance, powdering resistance, lubricity and paint adhesion. The present invention relates to an environmentally friendly, environmentally friendly zinc phosphate composite-treated steel sheet that is excellent in heat resistance and does not perform sealing with a chromic acid aqueous solution.

[0002]

2. Description of the Related Art Conventionally, surface-treated steel sheets for automobile bodies include electric Zn-Ni alloy-plated steel sheets, organic composite coated steel sheets (electric Zn-Ni alloy plating + chromate film + organic film), and alloyed hot-dip galvanized steel sheets. It was mainly used. However, in recent years, automakers
From the viewpoint of cost reduction, studies are being made to use less expensive pure galvanized steel sheets as body steel sheets for automobiles. However, pure galvanized steel sheets have the problem that the plating layer itself is soft and the melting point is low, so that the plating and the tool are easily welded during press forming, and press cracking and the like are liable to occur when processing parts with complex shapes. The development of materials with excellent properties was required. Therefore, the following technology has been proposed.

[0003] (1) Japanese Patent Application Laid-Open No. Hei 7-138768 (hereinafter referred to as Prior Art 1) discloses that zinc and phosphorus are formed on a surface of a zinc-containing metal-plated steel sheet at a specific weight ratio and a specific metal is specified. Having a zinc phosphate coating layer containing a weight ratio,
A zinc phosphate treated steel sheet further having a lubricating oil layer thereon has been proposed.

(2) Japanese Patent Application Laid-Open No. 09-049086 (hereinafter referred to as Prior Art 2) discloses that an electrogalvanized steel sheet is made of phosphate ion, zinc ion, magnesium ion,
There is disclosed a method for producing an electroplated steel sheet having high whiteness and excellent coatability, wherein the treatment is performed under specific processing conditions using a processing liquid containing nickel ions or the like at a specific content.

However, although the zinc phosphate treated steel sheets disclosed in the above prior arts 1 and 2 show some improvement in lubricity, the improvement effect is not at a satisfactory level. Due to the porous structure of the film, it is difficult for the electrodeposition coating to turn around, such as inside the mating flange or hemming part of the car body, and corrosion resistance in areas where the steel sheet is likely to be exposed even after the electrodeposition coating Was inferior. Further, the electroplated steel sheet manufactured by the technique disclosed in the above prior art 2 has a sufficient level of paint adhesion and corrosion resistance after coating under a multilayer coating of two or more coats applied to a steel sheet for an automobile body. It was not something.

As a technique for improving the corrosion resistance of a zinc phosphate-treated steel sheet, a post-treatment called sealing treatment with a chromic acid-based aqueous solution is conventionally performed after zinc phosphate treatment in the field of steel sheets for household appliances. I was However, in this conventional sealing technology for zinc phosphate treated steel sheets, since it contains hexavalent chromium, which is an environmentally regulated substance, it is desired to develop a technology that does not contain chromium, and the following technologies have been proposed.

(3) JP-A-56-136979 (hereinafter referred to as Prior Art 3) discloses that a cold-rolled steel sheet and a galvanized steel sheet are subjected to a phosphate treatment and immediately thereafter contain a chelating agent as a main component. A post-treatment method has been proposed.

(4) JP-A-58-197284 (hereinafter referred to as Prior Art 4) discloses that an aqueous solution containing polyacrylic acid and an aromatic polyhydric alcohol after subjecting a galvanized steel sheet to a phosphate treatment. There has been proposed a method for pre-painting a zinc-based plated steel sheet, which is characterized in that the method is applied.

(5) JP-B-63-4916 (hereinafter referred to as Prior Art 5) has a phosphate film of 1-2 g / m ² on a Zn-Ni alloy plating, and further has an upper layer. A highly durable composite plated steel sheet having a polymer film of 5 to 10 μm has been proposed.

[0010]

However, the above-mentioned conventional zinc phosphate-treated steel sheets have the following problems, respectively. That is, the zinc phosphate treated steel sheets shown in the prior arts 3 and 4 do not have the paint adhesion at the level required for a steel sheet for automobiles because a normal zinc phosphate film is used. Further, in the organic sealing disclosed in these prior arts, an alkali or acid solution is used in an assembly process of an automobile body [shear → press → welding → alkali degreasing → chemical formation → electrocoating → middle / overcoating]. , The coating was dissolved or deteriorated, and the corrosion resistance was poor.

[0011] The zinc phosphate treated steel sheet shown in the prior art 5 uses a normal zinc phosphate coating as in the above prior arts 3 and 4, and therefore has the level of paint adhesion required for a steel sheet for automobiles. Do not have. In addition, since the thickness of the organic film is as large as 5 to 10 μm, not only welding by spot welding is extremely difficult, but also the film is easily peeled off by bending and bending back at the bead portion during press forming (powdering resistance). Inferior properties), the exfoliated material deteriorates lubricity, so that press formability was also poor.

As described above, none of the conventional techniques can satisfy all of corrosion resistance, powdering resistance, lubricity, paint adhesion, and weldability.

The present invention has been made in view of such problems of the prior art, and has excellent corrosion resistance, powdering resistance, lubricity, paint adhesion, and weldability, and does not contain chromium. An object of the present invention is to provide an environmentally friendly surface-treated steel sheet.

[0014]

Means for Solving the Problems The present inventors have made intensive studies on the coating composition of the zinc phosphate composite-treated steel sheet and the relationship between its corrosion resistance, powdering resistance, lubricity, paint adhesion, and weldability. As a result, the following findings were obtained.

(1) In order to improve the corrosion resistance, paint adhesion, lubricity, and powdering resistance, the composition of zinc phosphate as the first layer is optimized, and the layer is specified as a sealing treatment on the upper layer of the zinc phosphate film. It is effective to form a two-layer structure provided with an organic film mainly composed of the above organic resin.

(2) Corrosion resistance is further improved by adding a specific rust preventive additive to the organic film at a specific content, without deteriorating lubricity, paint adhesion and weldability.

(3) By adding a specific lubricant in a specific content to the organic coating, the lubricity and the powdering resistance are further improved without deteriorating the corrosion resistance, paint adhesion and weldability.

(4) By optimizing the adhesion amount of the zinc phosphate film as the first layer and the adhesion amount of the organic film as the second layer, lubricity, corrosion resistance, paint adhesion, weldability, and Powdering property is improved.

The present invention has been made based on such knowledge, and is characterized by having the following configuration.

That is, according to the present invention, a zinc-coated steel sheet having a coating amount of 0.2 to 2.5 g / m ² containing at least one selected from nickel, manganese and magnesium as a first layer is provided. An organic resin having a zinc phosphate coating layer and a second layer coating on the upper surface of which is mainly composed of at least one organic resin selected from an ethylene resin, an epoxy resin, a urethane resin and an acrylic resin. An object of the present invention is to provide a zinc phosphate composite treated steel sheet having a coating and excellent in corrosion resistance, powdering resistance, lubricity, and paint adhesion.

The content of at least one selected from nickel, manganese and magnesium contained in the zinc phosphate coating is preferably 0.5 to 8.5% by mass in total.

It is preferable that the organic film as the second layer contains a solid lubricant and / or a rust preventive additive as components other than the organic resin.

The rust preventive additive is preferably at least one selected from silica and phosphate.
The silica is preferably at least one selected from ion-exchange silica, fumed silica, and colloidal silica. Further, the ion exchange silica is preferably Ca exchange silica.

It is preferable that the phosphate is at least one selected from calcium, aluminum and zinc phosphates.

The solid lubricant is preferably at least one selected from polyethylene wax, tetrafluoroethylene resin and boron nitride. The solid lubricant preferably has an average particle size of 0.05 to 25 μm. Further, the polyethylene wax preferably has a softening point of 100C to 135C.

The content of the rust-preventive additive contained in the organic coating is preferably 1 to 100 parts by weight based on 100 parts by weight of the organic resin as solids.
The content of the solid lubricant is preferably 1 to 80 parts by weight based on 100 parts by weight of the organic resin in solid content.

Further, the amount of the organic film to be applied is 0.0
It is preferably from ⁵ to 1.5 g / m2.

It is preferable that a rust-preventive oil film layer is formed on the outermost layer as a third layer in an amount of 0.01 to 10 g / m ² .

The surface-treated steel sheet of the present invention can be applied not only to automobiles and home appliances but also to construction materials and the like.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below together with the reasons for limiting the same.

The steel sheet used as the substrate of the galvanized steel sheet used in the present invention includes cold-rolled steel sheets for general working (CQ) to cold-rolled steel sheets for deep drawing (DQ) and cold-rolled steel sheets for deep and deep drawing (DD).
Q), all cold-rolled steel sheets for ultra-drawing (EDDQ), including soft-rolled cold-rolled steel sheets, and everything from high-strength steel sheets with bake hardenability and relatively low strength to general high-strength steel sheets exceeding 390 MPa. High-strength steel sheet, descaled hot-rolled steel sheet, etc. can be used.

As the plating layer of the zinc-based plated steel sheet, Z
n plating, Zn-Ni alloy plating (Ni content 10-1)
5% by mass), Zn-Fe alloy plating (Fe content 5 to 2)
5 mass% or 60 to 90 mass%), Zn-Mn alloy plating (Mn content 30 to 80 mass%), Zn-Co alloy plating (Co content 0.5 to 15 mass%), Zn-Cr
Alloy plating (Cr content 5-30% by mass), Zn-Al
Alloy plating (Al content: 3 to 60% by mass). In addition, Co, Fe, Ni, Cr
And oxides and salts such as silica, alumina, and hardly soluble chromate, and polymers. In addition, it is also possible to form a multilayer plating in which two or more of the same or different plating layers are plated.

The plated steel sheet may be one in which the surface of the steel sheet is preliminarily plated with a thin coat of Ni or the like, and the above-mentioned various platings are further provided thereon.

These platings can be formed by any of an electrolytic method, a melting method, and a gas phase method. The coating weight is preferably 10 g / m ² or more. If the coating weight is less than 10 g / m ² , there is a problem because the corrosion resistance is poor. In the case of Zn—Ni alloy plating, Zn—Fe alloy plating, Zn—Mn alloy plating, Zn—Co alloy plating, and Zn—Cr alloy plating, the plating adhesion amount is 6
If it exceeds 0 g / m ² , the powdering resistance is inferior.
It is preferably from 0 to 60 g / m ² . In order to secure higher corrosion resistance and powdering resistance, the plating adhesion amount is more preferably 15 to 60 g / m ² .

In order to prevent film defects and unevenness when a zinc phosphate composite film described later is formed on the surface of the plating film, alkali degreasing, solvent degreasing, surface adjustment, and the like are performed on the plating film surface in advance as necessary. Processing (for example, (1) N
treatment with an acidic or alkaline aqueous solution containing at least one metal ion selected from i ions, Co ions, and Fe ions, (2) treatment with a titanium colloid aqueous solution, (3) formed on the surface of a plated steel sheet Inorganic oxides, organic acids, EDT
A, a process of etching using a chelating compound such as NTA), and the like. As described above, the effects of the present invention can be obtained when any of these steel plates is used as the substrate.

The first of these galvanized steel sheets is
A zinc phosphate film is formed as a layer, and an organic film is formed thereon as a second layer. The zinc phosphate coating of the first layer improves paint adhesion by an anchor effect,
By preventing direct contact between the steel plate and the tool during sliding, it also contributes to improving lubricity.

In the present invention, a zinc phosphate film containing at least one selected from nickel, manganese and magnesium is used. This film is presumed to be present in a form in which a part of zinc in the zinc phosphate film has been replaced with the above-mentioned metal contained in the film.
Interaction with the organic layer as the upper layer works to provide excellent corrosion resistance, powdering resistance, lubricity, and paint adhesion.

The content of at least one selected from nickel, manganese and magnesium in the zinc phosphate coating is preferably 0.5 to 8.5% by mass in total. By setting the total content of these metals in the coating within the above range, corrosion resistance, lubricity, and paint adhesion are further improved. When particularly excellent corrosion resistance and paint adhesion are required, the total content of nickel, manganese or magnesium is more preferably 3 to 6% by mass. In addition, nickel and manganese in the zinc phosphate coating,
By containing nickel and magnesium, and nickel, manganese and magnesium together, corrosion resistance and paint adhesion are remarkably improved.

The amount of the zinc phosphate film as the first layer is preferably in the range of 0.2 to 2.5 g / m ² . When the adhesion amount is less than 0.2 g / m ² , the paint adhesion,
If the corrosion resistance is inferior and exceeds 2.5 g / m ² , the spot weldability deteriorates, the powdering during sliding increases, and the lubricity also deteriorates. From the viewpoints of lubricity, paint adhesion, corrosion resistance, and weldability, a more preferable adhesion amount range is 0.5 to 1.5 g.
/ ^{M 2,} and most preferably 0.5 to 1.0 g / ^{m 2}
It is. As the zinc phosphate treatment method for forming the zinc phosphate film layer, it can be formed by any of a reactive treatment, a coating treatment, and an electrolytic treatment.

As the reaction type treatment, for example, after performing degreasing, water washing and surface conditioning treatment on a plated steel sheet, at least one selected from nickel, manganese and magnesium ions together with phosphate, nitrate and zinc ions. It can be formed by bringing an aqueous solution containing one kind as a main component into contact with a treatment liquid obtained by adding the following (1) and (2) as necessary, washing with water, and drying.

(1) At least one selected from iron ions, cobalt ions and calcium ions.

(2) At least one selected from peroxide, fluoride ion, complex fluoride ion and nitrite ion.

As the coating type treatment, a zinc phosphate treatment solution containing at least one selected from nickel ions, manganese ions and magnesium ions together with phosphate ions, nitrate ions and zinc ions is applied to a plated steel sheet. At least on one side. The coating method is optional, and in addition to coating by a roll coater method, it is also possible to adjust the coating amount by an air knife method or a roll drawing method after coating by a dipping method or a spray method. A zinc phosphate coating can be formed by applying a zinc phosphate treatment solution to the surface of a plated steel sheet and then drying it using a dryer, a hot air oven, a high-frequency induction heating oven, or an infrared oven.

The drying temperature is preferably 70 to 400 ° C. in terms of the ultimate plate temperature. When the drying temperature is lower than 70 ° C., the drying of the film is insufficient and not only the stickiness of the film and deterioration of the paint adhesion, but also
When the second organic film is formed, the coating film becomes uneven.
On the other hand, if the ultimate plate temperature exceeds 400 ° C., further effects cannot be obtained, which is not only uneconomical, but also tends to cause defects in the coating film, resulting in poor corrosion resistance. From such a viewpoint, the more preferable baking temperature is 100 to 300 ° C., and most preferably 1 to 300 ° C.
20-170 ° C.

Next, an organic film formed as a second layer on the zinc phosphate film will be described. In the present invention, the organic film formed on the zinc phosphate film is mainly composed of at least one organic resin selected from an ethylene resin, an epoxy resin, a urethane resin and an acrylic resin. It is an organic film that has good paint adhesion,
Corrosion resistance is obtained. Specifically, for example, the following resins can be used.

Examples of the ethylene-based resin include ethylene-based copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and carboxyl-modified polyolefin resin; ethylene-unsaturated carboxylic acid copolymer;
Ethylene ionomers and the like, as well as resins obtained by modifying these resins with other alkyd resins, epoxy resins, phenolic resins, and the like.

As the epoxy resin, a glycidyl group is introduced by reacting a polyphenol such as bisphenol A, bisphenol B, bisphenol F, and novolak phenol with an epihalohydrin such as epichlorohydrin, or the glycidyl group introduction reaction. An aromatic epoxy resin obtained by further reacting a polyphenol with the product to increase the molecular weight, an aliphatic epoxy resin, an alicyclic epoxy resin and the like can be mentioned. Among these epoxy resins, it is preferable that the number average molecular weight is 1500 or more, particularly when a film forming property at a low temperature is required.

Further, resins obtained by reacting various modifiers with an epoxy group or a hydroxyl group in the above-mentioned epoxy resin can also be mentioned. Examples thereof include epoxy ester resins obtained by reacting a drying oil fatty acid, and acrylic acid or methacrylic acid. Epoxy acrylate resin modified with polymerizable unsaturated monomer component, urethane modified epoxy resin reacted with isocyanate compound, polybasic acid modified epoxy resin, acrylic resin modified epoxy resin, alkyd (or polyester) modified epoxy resin, polybutadiene modified Epoxy resins, phenol-modified epoxy resins, amine or polyamine-modified epoxy resins, and the like can be given.

As the acrylic resin, for example, polyacrylic acid and its copolymer, polyacrylate and its copolymer, polymethacrylic acid and its copolymer,
Polymethacrylic acid esters and their copolymers, urethane-acrylic acid copolymers (or urethane-modified acrylic resins), styrene-acrylic acid copolymers, and the like, and these resins are replaced with other alkyd resins, epoxy resins, phenol resins, etc. And the like modified by the above method.

Examples of the urethane-based resin include a polycarbonate-based polyurethane resin, a polyester-based polyurethane resin, and a polyether-based polyurethane resin.

In the present invention, one kind of the above-mentioned organic resins can be used alone, or two or more kinds can be used in combination. When particularly excellent paint adhesion and corrosion resistance are required, it is preferable to use an epoxy resin, an ethylene resin, or an acrylic resin. These organic resins may be any of a water-soluble type, a water-dispersed type, an organic solvent-soluble type, and an organic solvent-dispersed type.

In the present invention, a rust-preventive additive or a solid lubricant can be blended in the organic film, if necessary, or both can be blended together.

When particularly excellent corrosion resistance is required, the addition of a rust preventive additive is effective. Rust inhibiting additives suitable for use in the present invention include silica, phosphates, molybdates, phosphomolybdates (eg, aluminum phosphomolybdate, etc.), organic phosphoric acids and salts thereof (eg,
Phytic acid, phosphonic acid and their metal salts, alkali metal salts, alkaline earth metal salts), organic inhibitors (eg, hydrazine derivatives, thiol compounds), and the like. One or more of these may be used. Can be.

Of these, silica and phosphates are more preferably used. Specific examples of the silica herein include ion-exchange silica in which metal ions such as calcium and magnesium are fixed on the surface of a powder of porous silica gel, fumed silica, colloidal silica, and organosilica sol. One or two or more can be used. Among these, the above-mentioned ion-exchange silica, fumed silica having a primary particle diameter of 5 to 50 nm, or colloidal silica can be more preferably used. More preferably, calcium ion exchange silica having a calcium concentration of 1% by mass or more is used.

The phosphate used in the present specification is not limited to the phosphate ion skeleton or the degree of condensation, but may be any of normal salt, dihydrogen salt, monohydrogen salt or phosphite. Further, the normal salt may include all condensed phosphates such as polyphosphate in addition to orthophosphate (eg, zinc phosphate, calcium phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.). . Among them, at least one selected from zinc, calcium, and aluminum phosphates can be more preferably used. Particularly excellent corrosion resistance can be obtained by blending the above silica and phosphate in combination.

In the present invention, by blending a solid lubricant in the organic film, more excellent lubricity can be imparted. Examples of suitable solid lubricants for use in the present invention include the following.

(1) Polyolefin wax, paraffin wax: for example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc. (2) Fluororesin wax: For example, polyfluoroethylene resin (polytetrafluoroethylene resin) Etc.), polyvinyl fluoride resin, polyvinylidene fluoride resin, etc. (3) Fatty acid amide type compounds: For example, stearic acid amide, palmitic acid amide, methylene bis stearamide, ethylene bis stearamide, oleic acid amide,
(4) metal soaps: for example, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc. (5) metal sulfides: for example, molybdenum disulfide, tungsten disulfide (6) ) Others: For example, graphite, fluorinated graphite, boron nitride.

When particularly excellent lubricity is required,
It is preferable to use at least one selected from polyethylene wax, polytetrafluoroethylene resin and boron nitride. In addition, by using a polyethylene wax and a polytetrafluoroethylene resin in combination, particularly excellent lubricity can be obtained.

The average particle size of the solid lubricant is 0.05 to 2
Preferably it is 5 μm. When the particle diameter is less than 0.05 μm, the surface area of the lubricant is increased due to the surface concentration of the lubricant, and the area occupied by the lubricant in the outermost layer of the organic film is increased, thereby deteriorating the paint adhesion. On the other hand, when the particle size exceeds 25 μm, the lubricant does not fall from the organic film, so that a predetermined lubricity cannot be obtained and the corrosion resistance is poor. In order to obtain excellent paint adhesion, corrosion resistance, lubricity, and powdering resistance, the average particle size is more preferably from 1 to 15 μm, most preferably from 3 to 10 μm. Further, by setting the softening point of the polyethylene wax to 100 ° C. to 135 ° C., more preferably 110 ° C. to 130 ° C., lubricity and powdering resistance are further improved.

The content of the lubricant and / or the rust-preventive additive contained in the organic film is such that the rust-preventive additive is 1 to 100 parts by weight based on 100 parts by weight of the organic resin as solids. The lubricant is 1 to 8 parts by weight based on 100 parts by weight of the organic resin in solid content.
It is preferably 0 parts by weight.

When the amount of the rust preventive additive is less than 1 part by weight based on 100 parts by weight of the organic resin, the effect of improving the corrosion resistance is not sufficient, and when it exceeds 100 parts by weight, the paint adhesion and lubricity deteriorate. A more preferred amount is 10 to 80 parts by weight, most preferably 20 to 70 parts by weight, from the viewpoint of paint adhesion, lubricity and corrosion resistance.

On the other hand, if the amount of the solid lubricant is less than 1 part by weight with respect to 100 parts by weight of the organic resin, the effect of improving lubricity is not sufficient, and if it exceeds 80 parts by weight, paint adhesion and corrosion resistance deteriorate. A more preferred amount is 3 to 50 parts by weight, most preferably 5 to 35 parts by weight from the viewpoint of paint adhesion, lubricity and corrosion resistance.

The organic coating of the present invention mainly comprises the above-mentioned organic resin and, if necessary, a rust preventive additive and / or a solid lubricant, but does not adversely affect the quality performance. In the limit, organic resins other than the above-mentioned resins (for example, alkyd resins, fluorine resins, acrylic silicone resins, silicone resins, phenol resins, melanin resins, amino resins), oxide fine particles such as alumina and zirconia, Conductive substances, coloring pigments (eg, condensed polycyclic organic pigments, phthalocyanine-based organic pigments, etc.), coloring dyes (eg, azo-based dyes, azo-based metal complex salt dyes, etc.), curing agents (eg, polyamine-based curing agents, Acid anhydride-based curing agent, methylol group-containing precondensate, latent curing agent, polyisocyanate having at least two isocyanate groups in one molecule DOO compound), Narumakusukezai, dispersibility improving agent, it is also possible to formulate one or more kinds of such anti-foaming agent.

The coating amount of the organic coating is 0.05 to 1.
5g / m²It is preferable that The coating weight is 0.0
5g / m²If it is less than 1.5 g, the corrosion resistance and lubricity are inferior and 1.5 g
/ M ²If it exceeds, weldability will deteriorate. Lubricity, corrosion resistance,
Paint adhesion, more preferable adhesion amount from the viewpoint of weldability,
0.1-1.0 g / m²And most preferably 0.2
~ 0.6 g / m²It is.

In the method for forming an organic film according to the present invention, the coating composition containing the organic resin and, if necessary, the rust preventive additive and / or the lubricant as a main component is formed by forming the zinc phosphate film described above. A coating is formed by applying the coating to at least one surface of the coated steel sheet and drying the coating. Before applying the coating composition, it is possible to optionally perform pretreatment such as washing with water and drying on the steel sheet on which the zinc phosphate film is formed.

The method of applying the coating composition to the steel sheet is optional. Usually, the coating is performed by a roll coater method, but it is also possible to adjust the coating amount by an air knife method or a roll drawing method after coating by a dipping method or a spray method.

The drying after applying the coating composition is as follows:
The drying can be performed using a dryer, a hot-blast furnace, a high-frequency induction heating furnace, or an infrared furnace. The drying temperature is 50
~ 300 ° C is preferred. If the drying temperature is lower than 50 ° C., the film is insufficiently dried, causing stickiness of the film, and the film is damaged when the roll is touched after drying, resulting in poor paint adhesion, corrosion resistance, and lubricity. If the ultimate plate temperature exceeds 300 ° C., no further effect can be obtained, which is disadvantageous in terms of manufacturing cost. From such a viewpoint, a more preferable baking temperature is 100 to 200 ° C, and most preferably 120 to 170 ° C.
It is.

The present invention includes a steel sheet having the above-mentioned coating structure on both sides or one side. Therefore, aspects of the present invention include, for example, the following.

(1) One side: steel sheet surface + zinc phosphate film + organic film, one side: steel sheet surface + zinc phosphate film (2) One side: steel sheet surface + zinc phosphate film + organic film, one side: steel sheet surface (3) Both sides: steel plate surface + zinc phosphate film + organic film.

In the present invention, a rust-preventive oil layer may be provided as a third layer further above the organic film layer. Examples of the rust preventive oil include a rust inhibitor (for example, an oil-soluble surfactant), a petroleum base (for example, a mineral oil and a solvent), an oil film conditioner (for example, a mineral oil, a crystalline substance, and a viscous substance), and an oxidant. Examples include ordinary rust preventive oils, cleaning rust preventive oils, lubricating rust preventive oils, and the like, which mainly contain an inhibitor (for example, a phenolic antioxidant) and a lubricant (for example, an extreme pressure additive). Usual rust preventive oils include fingerprint-removable rust preventive oil in which the base is dissolved and decomposed in a petroleum solvent, solvent-diluted rust preventive oil, petrolactam,
Lubricating oil-type rust-preventive oils based on wax, and vaporizable rust-preventive oils are exemplified.

The adhesion amount of the rust-preventive oil film is 0.01 to 10
g / m ² is preferred. Adhesion amount 0.01g / m
^If it is less than ² , the effect of attaching the rust-preventive oil is not obtained, and if the amount exceeds 10 g / m ² , the degreasing is poor and the paint adhesion is poor. In order to obtain better corrosion resistance and paint adhesion,
More preferably, the amount of adhesion is 0.5 to 3 g / m ² .

[0072]

Example: Plate thickness 0.7 mm, surface roughness (Ra) 1.0 μ
m of a cold-rolled steel sheet, and a zinc-based plating was applied thereto to prepare a plated steel sheet. The plated steel sheet was subjected to alkali degreasing, water washing, and surface conditioning treatment, and then contacted with a zinc phosphate treatment liquid, washed with water, and dried to prepare a zinc phosphate treated steel sheet. Next, the coating composition was applied to the zinc phosphate-treated steel sheet using a roll coater, dried without washing with water, and then coated with a rust-preventive oil or a cleaning oil. The surface-treated steel sheet thus obtained was subjected to lubricity, powdering resistance, corrosion resistance, paint adhesion, and weldability tests. Specific conditions are as shown below.

(Example 1) (1) Plated steel sheet Table 1 shows the types of plating and the coating weight of the zinc-based plated steel sheet used in this example.

(2) Zinc phosphate composite treatment The coated steel sheet was degreased and washed with water to clean the surface, and then the surface conditioning liquid, the chemical composition of the zinc phosphate treatment liquid, the treatment temperature and the treatment time were adjusted. Table 2 with different coating amount and coating composition
Was prepared. The following is an example of a method for producing a zinc phosphate-treated steel sheet.

[Zinc phosphate composite coated steel sheet 1] Degreasing (FC
L4480 (manufactured by Nippon Parkerizing Co., Ltd.), 18 g
/ Liter (hereinafter referred to as L), 45 ° C., 120-second spree), and then a water-washed (20-second, spray) -coated steel sheet (A in Table 1) is subjected to a surface conditioning treatment (Preparen Z (Nippon Parkerizing (Japan)). Co., Ltd.), 1.5 g / L,
After spraying at room temperature for 2 seconds), it was immersed in the following zinc phosphate treatment solution heated to 45 ° C. for 1 second, washed with water and dried to prepare a zinc phosphate composite coated steel sheet 1.

[Zinc phosphate treatment liquid 1] Phosphate ion: 2
0 g / L, nitrate ion: 3 g / L, fluorine ion: 1.
5 g / L, zinc ion: 1.3 g / L, nickel ion: 0.5 g / L, manganese ion: 0.5 g / L, nitrite ion: 0.3 g / L, acid ratio (total acid / free acid) = 2
1 [Zinc phosphate composite coated steel sheet 2] A zinc phosphate composite coated steel sheet was used except that (B in Table 1) was used instead of (A in Table 1) as the plated steel sheet of the zinc phosphate composite coated steel sheet 1. The same processing as in No. 1 was performed.

[Zinc phosphate composite coated steel sheet 3] (C in Table 1) was used instead of (A in Table 1) as the plated steel sheet of the zinc phosphate composite coated steel sheet 1, and the zinc phosphate treatment time was 4 hours.
The same treatment as that of the zinc phosphate composite coated steel sheet 1 was performed except for the time.

(3) Coating composition (3-1) Organic resin Table 3 shows the organic resin used in the coating composition.

(3-2) Rust preventive additives Table 4 shows the rust preventive additives used in the coating composition.

(3-3) Lubricants Table 5 shows the solid lubricants used in the coating compositions.

(3-4) Paint Composition The paint composition used in this example is shown in Table 6.

(4) Rust preventive oil Table 7 shows the rust preventive oil used in this example.

[0083]

[Table 1]

[0084]

[Table 2]

[0085]

[Table 3]

[0086]

[Table 4]

[0087]

[Table 5]

[0088]

[Table 6]

[0089]

[Table 7]

[0090]

[Table 8]

Table 8 shows the structure of the surface-treated steel sheet prepared as described above, and the evaluation results of lubricity, powdering resistance, corrosion resistance, and paint adhesion.

The evaluation method of each characteristic is as follows.

Lubricity The pull-out force under the following sliding conditions was measured and evaluated by the coefficient of friction = (pull-out force) / (pressing force). The evaluation criteria are as follows.

(Sliding conditions) Tool contact area: 50 mm × 10 mm Tool material: SKD
11. Pressing force: 400kgf, sliding speed: 0.2m / m
in (Evaluation criteria) ：: 0.15 or less ：: More than 0.15 or less 0.17 or less △: More than 0.15 or less 0.20 or less ×: More than 0.20 powder - resistant material was sheared to a width of 30 mm. , Bead tip radius 0.5
mm, bead height: 4 mm, pressing force: 500 kg
f, After performing a draw bead test at a drawing speed of 200 mm / min, a portion of the bead that was slid was peeled off with an adhesive tape, and the amount of plating peeling per unit area before and after the test was measured. The evaluation criteria are as follows.

◎: 2 g / m ^{2 or} less ○ +: 2 g / m ² or more and less than 3 g / m ² ○: 3 g / m ² or more and less than 4 g / m ² Δ: 4 g / m ² or more, less than 6 g / m ² × : 6 g / m ² or more corrosion resistance 1) Bare corrosion resistance Defatted test material (FCL4 manufactured by Nippon Parkerizing Co., Ltd.)
460 (immersion at 45 ° C. for 120 seconds)), the edges and the back surface were tape-sealed, and the following accelerated corrosion test of a composite corrosion test cycle was performed. The evaluation criteria are shown below.

<Composite corrosion test cycle> Salt water spray 35 ° C. for 2 hours → drying 60 ° C. for 4 hours → 95% RH wet 50 ° C. for 2 hours <Evaluation criteria> ：: No red rust generated ○ +: Red rust area ratio less than 25 ○: Red rust Area ratio 25% or more and less than 50% △: Red rust area ratio 50% or more and less than 75% ×: Red rust area ratio 75% or more 2) Corrosion resistance after painting After coating the test material with the following three coats, cutter After cross-cutting with a knife and tape-sealing the end portion and the back surface, a corrosion promotion test of the following composite corrosion test cycle was performed, and evaluation was made on the one-side blister width from the cross-cut portion after 180 cycles. The evaluation criteria are shown below.

Coating (3 coats) Zinc phosphate treatment: SD6500MZ (standard conditions) Electrocoating: V20, 20 μm thick Intercoat: OT0870 (white color sealer)
Film thickness 35 μm Top coat: OT0647PT (Shast White)
Film thickness 35 μm <Composite corrosion test cycle> Salt spray 1 hour → Dry 6 hours → Wet 1 hour <Evaluation criteria> ： １: Less than 1 mm +: 1 mm or more and less than 2 mm ：: 2 mm or more and less than 4 mm △: 4 mm or more, 6 mm Less than ×: 6 mm or more Paint adhesion 1 After applying the three coats shown in 1 below to the test material, aging the coating for at least 24 hours, immersing it in ion exchange water at 50 ° C. for 240 hours, and then testing The piece was taken out, and within 30 minutes immediately after taking out, 100 pieces of gobangs were cut into the coating film at intervals of 2 mm, the adhesive tape was adhered and peeled, and the remaining rate of the coating film was evaluated. The evaluation criteria are shown below.

Coating (3 coats) Zinc phosphate treatment: SD6500MZ (standard conditions) Electrodeposition coating: V20, film thickness 20 μm Intermediate coating: OT0870 (white color sealer)
Film thickness 35 μm Top coat: OT0647PT (Shast White)
Thickness 35μm Evaluation criteria ◎: No peeling ○: Peeling of less than 3% △: Peeling of 3% or more and less than 10% ×: After degreasing the release rate of 10% or more paint adhesion 2 specimen, a commercial paint Derikon 0 at 700
The test piece was immersed in boiling water for 120 minutes, and then 100 pieces of gobangs at 1 mm intervals were cut into the coating film, and 5 m
m was subjected to Erichsen extrusion, the adhesive tape was peeled off from the processed part, and the residual ratio of the coating film was evaluated. The evaluation criteria are as follows.

[0099] Evaluation criteria ◎: No peeling ○: Peeling of less than 3% △: Peeling of 3% or more and less than 10% ×: Peeling of 10% or more weldability CF-type electrode, pressure 200 kgf, weld time 14 cycles / 50Hz A test was conducted at a welding current of 9 kA to evaluate the continuous spotting property. The evaluation criteria are as follows.

◎: 2500 points or more ○: 1500 points or more and less than 2500 points Δ: 500 points or more and less than 1500 points ×: less than 500 points

[0101]

[Table 9]

[0102]

[Table 10]

[0103]

[Table 11]

[0104]

[Table 12]

[0105]

[Table 13]

[0106]

[Table 14]

[0107]

[Table 15]

[0108]

[Table 16]

(Example 2) (1) Plated steel sheet In this example, the sheet thickness was 0.7 mm and the surface roughness (Ra) was 1.
An electrogalvanized steel sheet having a thickness of 0 μm and a coating weight of 20 g / m ² was used.

(2) Zinc phosphate composite treatment A zinc phosphate composite coated steel sheet shown in Table 10 below was prepared as a test material by the following treatment steps.

1) Degreasing → 2) Rinsing → 3) Surface conditioning → 4) Phosphate treatment → 5) Rinsing → 6) Drying Specific conditions in each treatment step are as follows.

1) Degreasing (FCL43366 (manufactured by Nippon Parkerizing Co., Ltd.), 20 g / L, sprayed at 45 ° C. for 60 seconds) 2) Washing with water (20 seconds, normal temperature, spray) 3) Surface adjustment treatment ((A) to below) (A) Preparen ZN (Nippon Parkerizing Co., Ltd.)
And 1.5 g / L at room temperature for 2 seconds.

(B) Five reciprocal brushings were performed with a brush using cashew fibers.

(C) (A) and (B) were performed simultaneously.

4) Phosphate treatment Table 9 shows the composition of the phosphatization solution, and Table 10 shows other treatment conditions and the film composition.

5) Rinse with water (20 seconds, room temperature, spray) 6) Dry (dry with hot air, 100 ° C., 3 minutes) (3) Coating composition (3-1) Organic resin The organic resin used for the coating composition is shown in Table 1. 3 is shown.

(3-2) Rust preventive additives Table 4 shows the rust preventive additives used in the coating compositions.

(3-3) Lubricants Table 5 shows the solid lubricants used in the coating compositions.

(3-4) Coating Composition Table 6 shows the coating compositions used in this example.

(4) Rust preventive oil Table 7 shows the rust preventive oil used in this example.

[0121]

[Table 17]

[0122]

[Table 18]

Table 11 shows the structure of the surface-treated steel sheet prepared as described above, and the results of evaluation of lubricity, powdering resistance, corrosion resistance, and paint adhesion. The evaluation method of each characteristic is the same as that of the first embodiment.

[0124]

[Table 19]

[0125]

As described above, the phosphate composite coated steel sheet of the present invention exhibits excellent lubricity and corrosion resistance, and also has excellent paint adhesion and weldability. It is extremely useful as a surface-treated steel sheet for building materials.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tatsuya Miyoshi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Nihon Kokan Co., Ltd. (72) Masaaki Yamashita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan F-term (reference) in this steel pipe Co., Ltd. AK04H AK12 AK12J AK18C AK18H AK22 AK22J AK25 AK25C AK25J AK41 AK51C AK53C AK70 AL01 BA03 BA04 BA07 BA10A BA10C BA10D CA14C CA19C DE01C EH46 EH71 EH71A GB32 JA04C JB02 JB02D JK06 JK16 YY00B YY00C YY00D 4K026 AA02 AA07 AA09 AA12 AA13 AA22 BA01 BA04 BA12 BB04 BB06 BB09 CA16 CA18 CA23 CA28 CA32 CA41 DA16 EB05 EB08

Claims (14)

[Claims] 1. An adhesion amount of at least one selected from nickel, manganese and magnesium as a first layer on a surface of a galvanized steel sheet, in an amount of 0.2 to 2.5 g /
has a zinc phosphate coating layer in m ^2, the main component thereon to ethylene-based resin as the second layer, an epoxy resin, at least one organic resin selected from among urethane resin and acrylic resin Zinc phosphate composite treated steel sheet with excellent corrosion resistance, powdering resistance, lubricity and paint adhesion characterized by having an organic coating. 2. The zinc phosphate film contains at least one selected from nickel, manganese and magnesium, and its content is 0.5 to 8.5% by mass in total.
The zinc phosphate composite-treated steel sheet according to claim 1, which is excellent in corrosion resistance, powdering resistance, lubricity, and paint adhesion. 3. The corrosion resistance according to claim 1, wherein the organic film as the second layer contains a solid lubricant and / or a rust preventive additive as a component other than the organic resin.
Zinc phosphate composite treated steel sheet with excellent powdering resistance, lubricity and paint adhesion. 4. The corrosion resistance, powdering resistance, lubricity and paint adhesion according to claim 3, wherein the rust preventive additive is at least one selected from silica and phosphate. Excellent zinc phosphate composite treated steel sheet. 5. The corrosion resistance, powdering resistance, lubricity, and paint according to claim 4, wherein the silica is at least one selected from ion-exchange silica, fumed silica, and colloidal silica. Zinc phosphate composite treated steel sheet with excellent adhesion. 6. The zinc phosphate composite treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity and paint adhesion according to claim 5, wherein the ion exchange silica is Ca exchange silica. 7. The corrosion resistance according to claim 4, wherein the phosphate is at least one selected from the group consisting of calcium, aluminum and zinc phosphates. Zinc phosphate composite treated steel sheet with excellent powdering properties, lubricity and paint adhesion. 8. A solid lubricant comprising polyethylene wax,
8. The method according to claim 3, wherein the resin is at least one selected from a tetrafluoroethylene resin and boron nitride.
The zinc phosphate composite treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paint adhesion according to any one of the above. 9. The solid lubricant having an average particle size of 0.05 to 2
9. The zinc phosphate composite-treated steel sheet according to claim 8, which is excellent in corrosion resistance, powdering resistance, lubricity, and paint adhesion. 10. The softening point of polyethylene wax is 100.
The zinc phosphate composite-treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paint adhesion, according to claim 8 or 9, wherein the temperature is in the range of 0 ° C to 135 ° C. 11. The content of the rust-preventive additive contained in the organic film is from 1 to 100 parts by weight of the organic resin in terms of solid content.
The zinc phosphate composite-treated steel sheet according to any one of claims 3 to 10, which is excellent in corrosion resistance, powdering resistance, lubricity, and paint adhesion, being 100 parts by weight. 12. The content of the solid lubricant contained in the organic film is 1 to 100 parts by weight of the organic resin in terms of solid content.
The zinc phosphate composite-treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paint adhesion according to any one of claims 3 to 11, which is 80 parts by weight. 13. An organic film having an adhesion amount of 0.05 to 1.
Corrosion resistance according to any one of claims 1 to 12, characterized in that a 5 g / m ^2, powdering resistance, lubricity, excellent zinc phosphate composite treated steel plate in paint adhesion. 14. The corrosion resistance according to any one of claims 1 to 13, wherein a rust-preventive oil film layer is formed on the outermost layer as a third layer in an amount of 0.01 to 10 g / m ² . Zinc phosphate composite treated steel sheet with excellent powdering resistance, lubricity and paint adhesion.