JP2000144448A - Organic coated steel sheet excellent in corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart excellent corrosion resistance to a steel sheet in a non- pollutive state by forming a film of an organic resin contg. a specified amt. of ion exchange silica to have a specified thickness, on the surface of a galvanized steel sheet or an aluminum plated steel sheet. SOLUTION: On the surface of a galvanized steel sheet (such as a Zn-Ni alloy plated steel sheet) or an aluminum plated steel sheet (such as an Al-Si alloy plated steel sheet), an organic film with 0.1 to 5 μm film thickness contg. ion exchange silica by 1 to 100 pts.wt. (solid content) to 100 pts.wt. (solid content) of organic resin for forming film is formed. As the organic resin, an organic high polymer resin having an OH and/or COOH group, desirably, an epoxy resin (such as bisphenol A) and/or a modified epoxy resin (such as an epoxy ester resin) is used, by which a dense barrier film is formed. The ion exchange silica is the one obtd. by fixing the metallic ions of calcium, magnesium or the like to the surface of porous silica gel powder and is blended as a rust preventive additive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic coated steel sheet which is most suitable for use in automobiles, home appliances, building materials, etc. Environmentally-friendly surface treatment that does not contain any heavy metals such as chromium, lead, cadmium, and mercury that are harmful to the environment and humans during manufacturing and in products, in order to adapt to environmental issues such as volatilization and elution of harmful substances from products. It relates to a steel plate.

[0002]

2. Description of the Related Art Steel sheets for home appliances, building materials, and automobiles have been used to improve the corrosion resistance (white rust resistance, red rust resistance) on the surface of a zinc-based or aluminum-based steel sheet. A steel sheet which has been subjected to chromate treatment with a treatment liquid containing chromic acid, bichromic acid or salts thereof as a main component is widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.

[0003] However, since chromate treatment uses hexavalent chromium, which is a pollution control substance, it is difficult for chromate salts to have an adverse effect on the human body in the treatment process, and it is difficult to dispose of chromium sludge after wastewater treatment. In addition, there are various problems, for example, that hexavalent chromium may be eluted from the product after the chromate treatment. For this reason, as the use control standards for chromic acids have become stricter, the management of chromate treatment plants, wastewater treatment, and secondary contamination by chromate treatment have become problems, and in response to this, each plant has closed drainage relations. In addition, measures are taken to minimize the emission of chromium ions to the outside.
In addition, in the process of degreasing the rust-preventive oil and press oil attached to the chromate-treated steel sheet by the user, when using an alkaline degreasing solution, the elution of chromium into the degreasing solution is considerably increased. Dechrome treatment is required.

[0004] In view of such circumstances, in order to prevent the generation of white rust on a zinc-based plated steel sheet, many pollution-free treatment techniques not based on chromate treatment have been proposed. Among them, several methods using an organic compound or an organic resin have been proposed, and for example, the following methods can be mentioned.

(1) A method using tannic acid (for example,
(2) A method of using a thermosetting paint in which an epoxy resin, an amino resin and tannic acid are mixed (for example, JP-A-63-971).
No. 0581) (3) A method using a mixed composition of an aqueous resin and a polyhydric phenol carboxylic acid (for example, JP-A-8-325760)
Using the chelating power of tannic acid, such as

(4) A surface treatment method of applying an aqueous solution of a hydrazine derivative to the surface of a tin or zinc iron plate (for example,
JP-B-53-27694, JP-B-56-10386
(5) A method using a rust inhibitor containing an amine addition salt obtained by adding an amine to a mixture of acyl sarcosine and benzotriazole (for example, JP-A-58-130284)
(6) A method using a treating agent in which a heterocyclic compound such as a benzothiazole compound and tannic acid are mixed (for example, JP-A-57-198267)

[0007]

However, these prior arts have the following problems. First, all of the above methods (1) to (4) have a problem in terms of corrosion resistance and the like. That is, the method (1) is insufficient in corrosion resistance and cannot provide a uniform appearance after the treatment. In addition, the method (2) is particularly suitable for forming a thin film (0.1 to 5 μm) directly on a zinc-based or aluminum-based plating surface.
m) is not intended to form a rust-preventive film. Therefore, even when applied in a thin film form to a zinc-based or aluminum-based plating surface, a sufficient anticorrosion effect cannot be obtained. Similarly, the method (3) is also insufficient in corrosion resistance.

Further, the method (4) is not applied to a zinc-based or aluminum-based plated steel sheet. Even if applied to a zinc-based or aluminum-based plated steel sheet, the obtained film has a network structure. It does not have sufficient barrier properties due to lack of corrosion resistance, and therefore has insufficient corrosion resistance. In addition, Japanese Patent Publication No. 53-23772
And JP-B-56-10386, in which a water-soluble polymer compound (polyvinyl alcohol, maleic acid ester copolymer, acrylic acid ester copolymer, etc.) is mixed with an aqueous solution of a hydrazine derivative in order to improve the uniformity of the film. However, a simple mixture of an aqueous hydrazine derivative solution and a water-soluble polymer compound does not provide sufficient corrosion resistance.

Further, the methods (5) and (6) are not aimed at forming a rust-preventive film on the surface of a zinc-based or aluminum-based plated steel sheet in a short time.
Even if the treating agent is applied to the surface of the plated steel sheet, excellent corrosion resistance cannot be obtained because there is no barrier to corrosion factors such as oxygen and water. As for the method (6), mixing with a resin (an epoxy resin, an acrylic resin, a urethane resin, a nitrocellulose resin, a vinyl chloride resin, etc.) as an additive is described, but a complex such as a benzothiazole compound is used. A simple mixture of a ring compound and a resin does not provide sufficient corrosion resistance.

In any of the above methods (1) to (6), practical conditions such as alkali degreasing at a pH of about 9 to 11 using a spray or the like to remove oil applied to the surface by press working or the like. However, there is a problem that the film is peeled or damaged by alkali degreasing, and the corrosion resistance cannot be maintained. Therefore, these methods are not suitable for practical use as a method for forming a rust preventive film. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an organic-coated steel sheet which is safe, harmless and has excellent corrosion resistance even during the manufacturing process and use.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet may be formed, if necessary, on a surface other than a chromate film. After forming the treated film, by forming an organic film containing a specific rust preventive additive, it is non-polluting and excellent in corrosion resistance without performing chromate treatment that may have a bad effect on the environment and the human body It has been found that an organic coated steel sheet can be obtained. The present invention has been made based on such knowledge, and the characteristic configuration thereof is as follows.

[1] A film-forming organic resin (A) 100 is coated on the surface of a zinc-based steel sheet or an aluminum-based steel sheet.
The film thickness containing 1 to 100 parts by weight (solid content) of ion-exchanged silica (a) is 0.1 to 5 parts by weight (solid content).
Organic coated steel sheet with excellent corrosion resistance characterized by having an organic coating of μm.

[2] A film-forming organic resin (A) 100 is coated on the surface of a zinc-based steel sheet or an aluminum-based steel sheet.
1 to 100 parts by weight (solid content) of ion-exchanged silica (a) and fine-particle silica (b) in total with respect to weight part (solid content), and ion-exchanged silica (a) and fine-particle silica Weight ratio of content (solid content) of (b) (a) /
(B) is 1/99 to 99/1, and the film thickness is 0.1 to 5
Organic coated steel sheet with excellent corrosion resistance characterized by having an organic coating of μm.

[3] A film-forming organic resin (A) 100 is coated on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet.
1 to 100 parts by weight (solid content) of the ion-exchanged silica (a) and 1 to 100 parts by weight (solid content) of the solid lubricant (c) are added to 1 part by weight (solid content).
An organic coated steel sheet having excellent corrosion resistance, comprising an organic film having a thickness of 0.1 to 5 μm containing 80 parts by weight (solid content).

[4] A film-forming organic resin (A) 100 is coated on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet.
The ion-exchanged silica (a) and the fine particle silica (b) are 1 to 100 parts by weight (solids) in total, and the solid lubricant (c) is 1 to 80 parts by weight based on parts by weight (solids). (Solid content), and the weight ratio (a) / (b) of the content (solid content) of the ion-exchanged silica (a) and the fine particle silica (b) is from 1/99 to 99/1. An organic-coated steel sheet having excellent corrosion resistance, characterized by having an organic coating of 0.1 to 5 μm.

[5] In the organically coated steel sheet according to any one of the above [1] to [4], the film-forming organic resin (A) has an OH group and / or
Or an organic coated steel sheet having excellent corrosion resistance, which is an organic polymer resin having a COOH group. [6] The organic coated steel sheet having excellent corrosion resistance, wherein the organic polymer resin is a thermosetting resin in the organic coated steel sheet according to the above [5].

[7] The organically coated steel sheet according to the above [6], wherein the thermosetting resin is an epoxy resin and / or a modified epoxy resin. [8] In the organic-coated steel sheet according to any one of the above [1] to [7],
An organic-coated steel sheet having excellent corrosion resistance, characterized in that a surface of a zinc-based steel sheet or an aluminum-based steel sheet has a chemical conversion treatment film containing no hexavalent chromium and an organic film as an upper layer. [9] In the organic-coated steel sheet according to any one of the above [1] to [8],
An organic-coated steel sheet having excellent corrosion resistance, wherein the ion-exchanged silica in the organic coating is Ca-exchanged silica. [10] The organic-coated steel sheet according to [9], wherein the Ca-exchanged silica has an average particle size of 4 μm or less, and has excellent corrosion resistance. [11] The organic-coated steel sheet according to the above [9] or [10], wherein
An organic-coated steel sheet having excellent corrosion resistance, wherein the Ca concentration of the exchanged silica is 2 to 8 wt%.

The basic features of the organic coated steel sheet of the present invention are as follows:
After forming a chemical conversion treatment film on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet as required, a film-forming organic resin (A), preferably an organic polymer resin having an OH group and / or a COOH group ( More preferably, an organic film is formed by blending a suitable amount of ion-exchange silica (a) as a rust preventive additive with a thermosetting resin, particularly preferably an epoxy resin and / or a modified epoxy resin.

By incorporating ion-exchanged silica (a) as a rust-preventive additive into the organic film, the organic film can be provided with a self-healing function at the film defect. That is, when cations such as Na ions enter in a corrosive environment, Ca ions and Mg ions on the silica surface are released by an ion exchange action, and further, OH ions are generated by a cathode reaction in a corrosive environment, and the vicinity of the plating interface is generated. Increases, the Ca ions (or Mg ions) released from the ion-exchanged silica become Ca
It precipitates in the vicinity of the plating interface as (OH) ₂ or Mg (OH) ₂ , blocks defects as a dense and hardly soluble product, and suppresses the corrosion reaction. Further, it is also considered that the eluted zinc ions are exchanged for Ca ions (or Mg ions) and fixed on the silica surface.

Further, in addition to the anticorrosion effect of the ion-exchanged silica as described above, a film-forming organic resin (A)
By using an organic polymer resin having an OH group and / or a COOH group (preferably a thermosetting resin, more preferably an epoxy resin and / or a modified epoxy resin), the organic polymer resin can be used as a crosslinking agent. A dense barrier film is formed by the reaction, and this barrier film is
It has excellent ability to suppress permeation of corrosion factors such as oxygen, and OH groups and COOH groups in the molecule provide a strong bonding force to the substrate, so that particularly excellent corrosion resistance is obtained.

Further, in the organic coated steel sheet of the present invention, the ion exchange silica (a) and the fine particle silica (b) are contained in the organic film.
Is added to further improve the corrosion resistance. Since ion-exchange silica is mainly composed of porous silica and generally has a relatively large particle diameter of 1 μm or more, a rust-preventing effect as silica cannot be expected after Ca ions are released. For this reason, fine particle silica having a large specific surface area such as fumed silica or colloidal silica (primary particle diameter of 5 to 50 nm, preferably 5 to 20 n
m, more preferably 5 to 15 nm) is considered to promote the production of dense and stable corrosion products such as basic zinc chloride and suppress the production of zinc oxide (white rust). It is presumed that a particularly excellent anticorrosion effect can be obtained by such a composite rust prevention mechanism of ion exchange silica and fine particle silica.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention and the reasons for limiting the same will be described below. The zinc-coated steel sheet serving as a base of the organic coated steel sheet of the present invention includes a zinc-coated steel sheet, Zn-Ni
Alloy plated steel sheet, Zn-Fe alloy plated steel sheet (electroplated steel sheet and galvannealed steel sheet), Zn-Cr
Alloy plated steel sheet, Zn-Mn alloy plated steel sheet, Zn-C
o alloy plated steel sheet, Zn-Co-Cr alloy plated steel sheet,
Zn-Cr-Ni alloy plated steel sheet, Zn-Cr-Fe alloy plated steel sheet, Zn-Al alloy plated steel sheet (for example, Z
n-5% Al alloy plated steel sheet, Zn-55% Al alloy plated steel sheet), Zn-Mg alloy plated steel sheet, Zn-Al-
Mg-plated steel sheets, and zinc-based composite plated steel sheets (eg, Zn—SiO ₂ dispersed plated steel sheets) in which metal oxides, polymers, and the like are dispersed in the plating films of these plated steel sheets can be used.

Further, among the above-mentioned platings, a multi-layer plated steel sheet obtained by plating two or more layers of the same type or different types may be used. In addition, as the aluminum-plated steel sheet serving as the base of the organic-coated steel sheet of the present invention, an aluminum-plated steel sheet, an Al—Si alloy-plated steel sheet, or the like can be used. Further, the plated steel sheet may be one in which thin steel plating such as Ni is previously applied to the surface of the steel sheet and various platings as described above are applied thereon. As a plating method, any practicable method can be adopted among an electrolysis method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, and a gas phase method.

In order to prevent the occurrence of film defects and unevenness when a chemical conversion film or an organic film is formed on the surface of the plating film, if necessary, alkali degreasing, solvent degreasing, surface conditioning, etc. are performed on the plating film surface in advance. A treatment such as a treatment (alkaline surface conditioning treatment or acidic surface conditioning treatment) can be performed. Further, in order to prevent blackening (a kind of oxidation phenomenon on the plating surface) in the use environment of the organic coated steel sheet, if necessary, an iron group metal ion (Ni
Surface treatment with an acidic or alkaline aqueous solution containing ions, Co ions, and Fe ions) can also be performed. When an electrogalvanized steel sheet is used as a base steel sheet, an iron group metal ion (Ni ion, Co ion, Fe ion) is added to the electroplating bath for the purpose of preventing blackening.
And these metals can be contained in the plating film in an amount of 1 ppm or more. In this case, there is no particular upper limit on the iron group metal concentration in the plating film.

If necessary, a chromate film (6
Chemical conversion coatings other than chromium (valent chromium-containing coating) can be formed. This chemical conversion coating is formed for the purpose of suppressing the activity of the plated steel sheet and improving corrosion resistance and adhesion, and there is no limitation on the type of chemical conversion coating as long as it does not contain hexavalent chromium.

Examples of the chemical conversion film containing no hexavalent chromium include (1) a phosphate treatment film, (2) a passivation film such as a molybdate or tungstate treatment film, a phosphoric acid / molybdic acid treatment film, and the like. 3) Alkali silicate treatment film composed of alkali metal oxide such as lithium oxide and silicon oxide (4) Composite oxide film composed of trivalent chromium (5) Inorganic film such as oxide film composed of titanium oxide and zirconium oxide Can be applied.

In addition to the above inorganic coating, for example,
(6) Organic resin film or organic composite silicate film (7) Chelate-forming organic film such as tannic acid, phytic acid, phosphonic acid, etc. (8) Inorganic film of any of the above (1), (2) and (3) A composite film containing an organic resin therein can be used. Of the above, a hardly soluble film containing silicon oxide (eg, an alkali silicate film) is most desirable from the viewpoint of suppressing zinc white rust.

An organic resin can be incorporated into the chemical conversion coating for the purpose of improving workability and corrosion resistance. As the organic resin, an epoxy resin, a urethane resin, an acrylic resin, an acrylic-ethylene copolymer, an acrylic-styrene copolymer, an alkyd resin, a polyester resin, an ethylene resin, or the like can be used.
These can be supplied as a water-soluble resin and / or a water-dispersible resin. Furthermore, in addition to these water-dispersible resins,
It is effective to use a water-soluble epoxy resin, a water-soluble phenol resin, a water-soluble butadiene rubber (SBR, NBR, MBR), a melamine resin, a blocked isocyanate, an oxazoline compound or the like as a crosslinking agent.

In addition, the above-mentioned chemical conversion treatment film may be further added with a polyphosphate, as an additive for further improving the corrosion resistance.
Phosphates (eg, zinc phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.), molybdates, phosphomolybdates (eg, aluminum phosphomolybdate), organic phosphoric acids and salts thereof (eg, phytic acid) Phytate, phosphonic acid, phosphonate and their metal salts, alkali metal salts), organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.), organic compounds (polyethylene glycol), etc. May be added.

Further, as other additives, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.) ), Inorganic pigments (titanium oxide), chelating agents (thiols, etc.), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, Silane coupling agents, titanium coupling agents, etc.), melamine / cyanuric acid adducts, and the like.

For the purpose of preventing blackening (a kind of oxidation phenomenon on the plating surface) of the organic-coated steel sheet under the use environment, these chemical conversion treatment films are coated with iron group metal ions (Ni ion, C ion).
o ions, Fe ions), preferably Ni ions. In this case, the desired effect can be obtained if the concentration of the iron group metal ion is 1/10000 mol or more with respect to 1 mol of the (β) alkaline earth metal ion in the treatment composition. Although the upper limit of the concentration of the iron group metal ion is not particularly defined, it is set to such an extent that the increase in the concentration does not affect the corrosion resistance. The thickness of these chemical conversion coatings is 3 μm or less. This is because when the film thickness exceeds 3 μm, workability and conductivity are reduced. The lower limit is not particularly defined, but may be a film thickness at which the effect of improving corrosion resistance is recognized.

On the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, the above-mentioned chemical conversion treatment film is formed, if necessary, and then an organic film containing a specific rust preventive additive is formed. The base resin of the organic film is not particularly limited, and any of a water-soluble resin, a water-dispersible resin, and an organic solvent-soluble resin can be used. From the viewpoint of corrosion resistance, an organic resin having an OH group and / or a COOH group is particularly preferable. It is preferable to use the polymer resin (A). Among them, a thermosetting resin is preferable, and an epoxy resin or a modified epoxy resin is most preferable. Examples of the organic polymer resin having an OH group and / or a COOH group include an epoxy resin, a polyhydroxy polyether resin,
Acrylic copolymer resins, ethylene-acrylic acid copolymer resins, alkyd resins, polybutadiene resins, phenol resins, polyurethane resins, polyamine resins, polyphenylene resins, and mixtures or addition polymers of two or more of these resins No.

(1) Epoxy resin As the epoxy resin, epoxy resin obtained by glycidyl etherification of bisphenol A, bisphenol F, novolak, etc., propylene oxide to bisphenol A,
Epoxy resins added with ethylene oxide or polyalkylene glycol and converted to glycidyl ether, furthermore, aliphatic epoxy resins, alicyclic epoxy resins, polyether epoxy resins, and the like can be used. These epoxy resins desirably have a number average molecular weight of 1500 or more, particularly when curing at a low temperature is required. The above epoxy resins can be used alone or in combination of different types.

Examples of the modified epoxy resin include resins in which various modifiers are reacted with an epoxy group or a hydroxy group in the above epoxy resin. For example, an epoxy ester resin obtained by reacting a carboxyl group in a drying oil fatty acid,
Epoxy acrylate resin modified with acrylic acid, methacrylic acid, etc., urethane modified epoxy resin obtained by reacting isocyanate compound, amine-added urethane modified epoxy resin obtained by adding alkanolamine to urethane modified epoxy resin obtained by reacting isocyanate compound with epoxy resin, etc. Can be mentioned.

The above polyhydroxy polyether resin is
A polymer obtained by polycondensing a mononuclear or dinuclear phenol or a mixture of mononuclear and dinuclear phenols with an approximately equimolar amount of epihalohydrin in the presence of an alkali catalyst. . Representative examples of mononuclear dihydric phenols include resorcin, hydroquinone, and catechol. Representative examples of dinuclear phenols include bisphenol A. These may be used alone or in combination of two or more. You may.

(2) Urethane resin Examples of the urethane resin include an oil-modified polyurethane resin, an alkyd-based polyurethane resin, a polyester-based polyurethane resin, a polyether-based urethane resin, and a polycarbonate-based polyurethane resin. (3) Alkyd resin Examples of the alkyd resin include oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin,
Styrenated alkyd resin, silicon-modified alkyd resin,
Acrylic-modified alkyd resins, oil-free alkyd resins, high-molecular-weight oil-free alkyd resins, and the like can be given.

(4) Acrylic resin Examples of the acrylic resin include polyacrylic acid and its copolymer, polyacrylic ester and its copolymer, polymethacrylic ester and its copolymer, and polymethacrylic ester. And a copolymer thereof, a urethane-acrylic acid copolymer (or urethane-modified acrylic resin), a styrene-acrylic acid copolymer, and the like. Further, these resins may be used in other alkyd resins, epoxy resins,
A resin modified with a phenol resin or the like may be used.

(5) Ethylene Resin (Polyolefin Resin) Examples of the ethylene resin include ethylene-based copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and carboxyl-modified polyolefin resin; Examples thereof include a saturated carboxylic acid copolymer and an ethylene ionomer. Further, a resin obtained by modifying these resins with another alkyd resin, an epoxy resin, a phenol resin, or the like may be used. (6) Acrylic silicone resin As the acrylic silicone resin, for example, a resin containing a hydrolyzable alkoxysilyl group in a side chain or a terminal of an acrylic copolymer as a main component, and a curing agent added thereto is exemplified. When these acrylic silicone resins are used, excellent weather resistance can be expected.

(7) Fluororesins Fluororesins include fluoroolefin copolymers, for example, monomers such as alkyl vinyl ether, synchroalkyl vinyl ether, carboxylic acid-modified vinyl ester, hydroxyalkyl allyl ether, tetrafluoropropyl There is a copolymer obtained by copolymerizing vinyl ether or the like with a fluorine monomer (fluoroolefin). When using these fluororesins,
Excellent weather resistance and excellent hydrophobicity can be expected.

Further, in order to lower the drying temperature of the resin, the core portion and the shell portion of the resin particles have different resin types or cores made of resins having different glass transition temperatures.
A shell-type water-dispersible resin can be used. In addition, by using a water-dispersible resin having self-crosslinking properties, for example, by providing an alkoxysilane group to the resin particles, a silanol group is generated by hydrolysis of the alkoxysilane during heating and drying of the resin, and a silanol group between the resin particles is formed. Cross-linking between particles using a dehydration condensation reaction of the above can be used. Further, as a resin used for the organic film, an organic composite silicate obtained by compounding an organic resin with silica via a silane coupling agent is also suitable.

In the present invention, in order to improve the corrosion resistance and workability of the organic film, it is particularly preferable to use a thermosetting resin. In this case, urea resin (butylated urea resin etc.), melamine resin (butylated melamine resin), butylated urea
Amino resins such as melamine resin and benzoguanamine resin,
A curing agent such as a blocked isocyanate, an oxazoline compound, and a phenol resin can be blended.

Among the organic resins described above, epoxy resins and ethylene resins are preferable in consideration of corrosion resistance, workability, and paintability, and particularly, thermosetting resins having excellent barrier properties against corrosion factors such as enzymes. Particularly preferred are epoxy resins and modified epoxy resins. As these thermosetting resins, a thermosetting epoxy resin, a thermosetting modified epoxy resin, an acrylic copolymer resin copolymerized with an epoxy group-containing monomer, a polybutadiene resin having an epoxy group,
Examples thereof include polyurethane resins having an epoxy group, and adducts or condensates of these resins. One type of these epoxy group-containing resins may be used alone, or two or more types may be used in combination.

In the present invention, ion-exchanged silica (a) is blended in the organic film as a rust preventive additive. Ion-exchanged silica is one in which metal ions such as calcium and magnesium are fixed on the surface of a porous silica gel powder, and the metal ions are released under a corrosive environment to form a precipitated film. In addition, Ca ion exchange silica is most preferable among the ion exchange silicas. Any Ca-exchanged silica can be used, but those having an average particle diameter of 6 μm or less, preferably 4 μm or less are preferable. For example, those having an average particle diameter of 2 to 4 μm can be used. If the average particle diameter of the Ca-exchanged silica exceeds 6 μm, the corrosion resistance decreases and the dispersion stability in the coating composition decreases. Ca
The Ca concentration in the exchanged silica is 1% by weight or more, preferably 2% by weight.
It is preferably about 8% by weight. Ca concentration is 1wt%
If the amount is less than the above range, a sufficient rust prevention effect due to the release of Ca cannot be obtained.

The surface area, pH and oil absorption of the Ca-exchanged silica are not particularly limited. Examples of such Ca-exchanged silica include WRGrace & Co. SHIEEL
DEX C303 (average particle size 2.5 to 3.5 μm, C
a concentration 3 wt%), SHIELDEX AC3 (average particle diameter 2.3 to 3.1 μm, Ca concentration 6 wt%), SHI
ELDEX AC5 (average particle size of 3.8 to 5.2 μm,
Ca concentration 6 wt%), S by Fuji Silysia Chemical Ltd.
HIELDEX (average particle diameter 3 μm, Ca concentration 6 to 8 w
t%), SHIELDEX SY710 (average particle size 2.2 to 2.5 μm, Ca concentration 6.6 to 7.5 wt%)
Etc. can be used. The anticorrosion mechanism when the ion-exchanged silica (a) is added to the organic film is as described above, and an extremely excellent anticorrosion effect is exhibited by the effect of the ion-exchanged silica to suppress corrosion in the cathode reaction section.

The amount of the ion-exchanged silica (a) in the organic resin film is 1 to 100 parts by weight (solid content), preferably 5 to 8 parts by weight, per 100 parts by weight (solid content) of the base resin.
0 parts by weight (solid content), more preferably 10 to 50 parts by weight (solid content). If the amount of the ion-exchanged silica (a) is less than 1 part by weight, the effect of improving corrosion resistance after alkali degreasing is small. On the other hand, if the amount exceeds 100 parts by weight,
It is not preferable because the corrosion resistance is reduced.

In the present invention, particularly excellent corrosion resistance can be obtained by adding ion-exchanged silica (a) and fine-particle silica (b) in the organic film in combination. That is, by adding the ion-exchanged silica (a) and the particulate silica (b) in combination, a particularly excellent anticorrosion effect can be obtained by the composite rust prevention mechanism of the two as described above.

Fine particle silica (b) is colloidal silica,
Any of fumed silica may be used. When colloidal silica is based on an aqueous film-forming resin,
For example, Snowtex O, Snowtex N, Snowtex 20, Snowtex 30, Snowtex 4
0, Snowtex C, Snowtex S (all manufactured by Nissan Chemical Industries, Ltd.), Cataloid S, Cataloid SI-
350, Cataloid SI-40, Cataloid SA, Cataloid SN (manufactured by Catalysis Chemical Industry Co., Ltd.), Adelaite AT-20-50, Adelaite AT-20N, Adelaite AT-300, Adelaite AT-300S, Adelaite AT20Q (all And Asahi Denka Kogyo Co., Ltd.) can be used.

When the solvent-based film-forming resin is used as a base, for example, the organosilica sol MA-ST-
M, organosilica sol IPA-ST, organosilica sol EG-ST, organosilica sol E-ST-ZL,
Organosilica Sol NPC-ST, Organosilica Sol DMAC-ST, Organosilica Sol DMAC-ST-
ZL, organosilica sol XBA-ST, organosilica sol MIBK-ST (Nissan Chemical Industries, Ltd.)
OSCAL-1132, OSCAL-1232,
OSCAL-1332, OSCAL-1432, OSC
AL-1532, OSCAL-1632, OSCAL-
1722 (both manufactured by Catalyst Chemical Industry Co., Ltd.) can be used. In particular, the organic solvent-dispersed silica sol has excellent dispersibility, and therefore has better corrosion resistance than fumed silica.

As fumed silica, for example, AEROSIL R971, AEROSIL R81
2, AEROSIL R811, AEROSIL R97
4, AEROSIL R202, AEROSIL R80
5, AEROSIL 130, AEROSIL 200,
AEROSIL 300, AEROSIL 300CF
(Above, manufactured by Nippon Aerosil Co., Ltd.) and the like.

The fine-particle silica contributes to the formation of a dense and stable zinc corrosion product in a corrosive environment, and the corrosion product is formed densely on the plating surface, thereby suppressing the promotion of corrosion. It is considered possible. From the viewpoint of corrosion resistance, the fine particle silica has a particle diameter of 5 to 50 n.
m, preferably 2 to 20, more preferably 5 to 15 nm
It is preferred to use

When the ion exchange silica (a) and the fine particle silica (b) are combined and added to the organic film, the amount of the ion exchange silica (a) and the fine particle silica (b) is based on 100 parts by weight (solid content) of the base resin. 1 in total amount of silica (b)
-100 parts by weight (solid content), preferably 5-80 parts by weight (solid content), and the weight ratio (a) of the compounding amount (solid content) of ion-exchanged silica (a) and fine-particle silica (b) /
(B) is from 99/1 to 1/99, preferably from 95/5 to 4
0/60, more preferably 90/10 to 60/40.

If the total amount of the ion-exchanged silica (a) and the finely divided silica (b) is less than 1 part by weight, the effect of improving the corrosion resistance after alkali degreasing is small. On the other hand, if the total compounding amount exceeds 100 parts by weight, the coatability and workability deteriorate, which is not preferable. If the weight ratio (a) / (b) of the ion-exchanged silica (a) and the fine particle silica (b) is less than 1/99, the corrosion resistance is poor, while the weight ratio (a) / (b) is 9
If it exceeds 9/1, the effect of the composite addition of the ion exchange silica (a) and the fine particle silica (b) cannot be sufficiently obtained.

In the organic film, in addition to the above-mentioned rust preventive additive, a polyphosphate (for example, aluminum polyphosphate: Teika K-WHIT manufactured by Teica Co., Ltd.) may be used as a corrosion inhibitor.
E80, Takeka K-WHITE84, Takeka K-WHI
TE105, Takeka K-WHITEG105, Takeka K
-WHITE90, etc.), phosphates (eg, zinc phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.), molybdate, phosphomolybdate (eg, aluminum phosphomolybdate), organic phosphoric acid and salts thereof (For example,
Phytic acid, phytate, phosphonic acid, phosphonate and their metal salts, alkali metal salts, alkaline earth metal salts), organic inhibitors (eg, hydrazine derivatives, thiol compounds, etc.) can be added.

A solid lubricant (c) can be added to the organic film, if necessary, for the purpose of improving the workability of the film. Examples of the solid lubricant applicable to the present invention include the following. (1) Polyolefin wax, paraffin wax:
For example, polyethylene wax, synthetic paraffin, natural paraffin, microwax, chlorinated hydrocarbon, etc. (2) Fluororesin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.), polyvinyl fluoride resin, polyvinylidene fluoride Resin, etc.

In addition, fatty acid amide compounds (eg, stearic acid amide, palmitic acid amide,
Methylenebisstearamide, ethylenebisstearamide, oleic amide, esylamide, alkylenebisfatty acid amide, etc., metal soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metals Sulfide (molybdenum disulfide, tungsten disulfide), graphite,
Graphite fluoride, boron nitride, polyalkylene glycol,
You may use alkali metal sulfate etc.

Among the above solid lubricants, polyethylene wax, fine particles of fluorine resin (particularly, poly-4
Fluorinated ethylene resin fine particles) are preferred. Examples of the polyethylene wax include Seridust 9615A, Seridust 3715, Seridust 3 manufactured by Hoechst Inc.
620, Seridust 3910, Sunwax 131-P and Sunwax 161-P manufactured by Sanyo Chemical Co., Ltd., Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-500, Chemipearl manufactured by Mitsui Petrochemical Co., Ltd.
W-800, Chemipearl W-950 and the like can be used.

As the fluororesin fine particles, tetrafluoroethylene fine particles are most preferable. For example, Lubron L-2 and Lubron L-L manufactured by Daikin Industries, Ltd.
5. MP1100, MP12 manufactured by Mitsui DuPont
00, Fluon Dispersion AD1, Fluon Dispersion AD2, Fluon L141J, Fluon L15 manufactured by Asahi ICI Fluoropolymers Co., Ltd.
0J, Fullon L155J and the like are preferable. Among these, a particularly excellent lubricating effect can be expected by using a combination of polyolefin wax and fine particles of tetrafluoroethylene.

The compounding amount of the solid lubricant (c) in the organic film is from 1 to 80 parts by weight per 100 parts by weight (solid content) of the base resin.
Parts by weight (solid content), preferably 3 to 40 parts by weight (solid content). If the amount of the solid lubricant (c) is less than 1 part by weight, the lubricating effect is poor. On the other hand, if the amount is more than 80 parts by weight, the coatability is undesirably reduced.

The organic coating film of the organic coated steel sheet of the present invention comprises a film-forming organic resin (A) as a base resin, and ion-exchanged silica (a) mixed therein. A lubricant (c), a curing agent, and the like are added. If necessary, an organic coloring pigment (for example, a condensed polycyclic organic pigment, a phthalocyanine-based organic pigment, or the like) or a coloring dye (for example, Organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.), inorganic pigments (eg, titanium oxide), chelating agents (eg, thiol, etc.), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, etc.) Iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, silane coupling agents, titanium coupling agents, etc.), melamine / cyanuric acid adducts, etc. Can. The coating composition for forming a film containing the base resin and the additive component usually contains a solvent (organic solvent and / or water), and further contains a neutralizing agent and the like as necessary.

The dry thickness of the organic film is 0.1 to 5 μm, preferably 0.3 to 3 μm, more preferably 0.5 to 2 μm.
μm. When the thickness of the organic film is less than 0.1 μm, the corrosion resistance is insufficient. On the other hand, when the thickness exceeds 5 μm, the conductivity and workability deteriorate.

Next, a method for producing the organic coated steel sheet of the present invention will be described. The organic-coated steel sheet of the present invention is obtained by subjecting the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet to a chemical conversion treatment as necessary, and then adding ion-exchanged silica (a) to the above-mentioned film-forming organic resin (A). It is manufactured by applying a coating composition to which fine particle silica (b), solid lubricant (c) and the like are added according to the above, and drying by heating. The surface of the plated steel sheet may be subjected to an alkali degreasing treatment as required before applying the treatment liquid, and may be subjected to a pretreatment such as a surface conditioning treatment in order to improve adhesion and corrosion resistance.

When a chemical conversion coating is formed on the surface of a plated steel sheet, the treatment liquid may be coated on the surface of the plated steel sheet by any of an application method, an immersion method, and a spray method. In the application method, a roll coater (3) is used. Any application means such as a roll method, a two-roll method, a squeeze coater, and a die coater may be used. Also,
After coating, dipping, and spraying with a squeeze coater or the like, adjustment of the coating amount, uniform appearance, and uniform film thickness can be performed by an air knife method or a roll drawing method.

After coating the treatment liquid as described above, washing with water if necessary, and then drying by heating. The method of heating and drying the coated treatment liquid is arbitrary, and for example, a means such as a dryer, a hot air oven, a high-frequency induction heating oven, and an infrared oven can be used. The heating and drying treatment is performed at a temperature of 40 to 350 ° C., preferably 80 to 200 ° C.
C., more preferably 80 to 160.degree. If the heating and drying temperature is lower than 40 ° C., a large amount of water remains in the film, and the corrosion resistance becomes insufficient. On the other hand, when the heating and drying temperature exceeds 350 ° C., not only is it uneconomical, but also the coating tends to have defects and the corrosion resistance is reduced.

After the formation of the chemical conversion treatment film as required, a coating composition for forming an organic film is applied.
As a method of applying the coating composition, a coating method, a dipping method,
Any method such as a spray method can be adopted. As a coating method, any method such as a roll coater (three-roll system, two-roll system, etc.), a squeeze coater, a die coater, and the like may be used. In addition, after the coating, dipping, or spraying with a squeeze coater or the like, it is also possible to adjust the coating amount, uniform the appearance, and uniform the film thickness by an air knife method or a roll drawing method.

After application of the coating composition, heating and drying are usually performed without washing with water, but a washing step may be performed after application of the coating composition. For the heating and drying treatment, a dryer, a hot blast furnace, a high-frequency induction heating furnace, an infrared furnace, or the like can be used. Heat treatment is 50-350 ° C at ultimate plate temperature,
It is desirable to carry out the reaction in the range of preferably 80 ° C to 250 ° C. If the heating temperature is lower than 50 ° C., a large amount of water in the film remains, and the corrosion resistance becomes insufficient. The heating temperature is 350 ° C
When it exceeds, it is not only uneconomical, but also there is a possibility that a defect occurs in the film and the corrosion resistance is reduced.

The present invention includes a steel sheet having the above-mentioned organic film on both sides or one side. Therefore, examples of the form of the steel sheet of the present invention include the following. (1) One side: Plating film-Chemical conversion film-Organic film, One surface: Plating film (2) One surface: Plating film-Chemical conversion film-Organic film, One surface: Plating film-Chemical conversion film (3) Both surfaces: Plating film- Chemical conversion coating-organic coating (4) One side: plating coating-chemical conversion coating-organic coating, one side: plating coating-organic coating (5) Both surfaces: plating coating-organic coating

[0067]

[0068]

EXAMPLE As an organic resin for forming an organic film, an organic resin shown in Table 3 was used. Ion exchange silica, fine particle silica shown in Table 4 and a solid lubricant shown in Table 5 were appropriately mixed with this resin composition, It was dispersed for a required time using a dispersing machine (sand grinder) to obtain a desired coating composition. The ion exchange silica is Ca exchange silica WRGrace &
SHIELDEX C303 (average particle size 2.
5-3.5 μm, Ca concentration 3 wt%).

In order to obtain an organically coated steel sheet for home appliances, building materials and automobile parts, the sheet thickness: 0.8 mm and the surface roughness Ra: 1.0
μm cold-rolled steel sheet was subjected to various zinc-based or aluminum-based plating, and the coated steel sheet shown in Table 1 was used as a processing base sheet. The surface of the plated steel sheet was subjected to alkali degreasing treatment, water washing and drying, and then, if necessary, as shown in Table 2. The chemical conversion treatment was performed under the conditions shown in (1). Next, a coating composition for forming an organic film was applied by a roll coater and dried by heating to form an organic film, thereby producing organic-coated steel sheets of Examples of the present invention and Comparative Examples. The thickness of the organic film was adjusted according to the solid content (heating residue) of the coating composition or the application conditions (roll rolling force, rotation speed, etc.).

The obtained organic-coated steel sheets were evaluated for quality performance (coating appearance, white rust resistance, white rust resistance after alkali degreasing, paint adhesion, workability). The results are shown in Tables 6 to 2 together with the composition of the chemical conversion coating and the organic coating.
It is shown in FIG. The evaluation of the quality performance of the organic coated steel sheet was performed as follows.

(1) Coating Appearance For each sample, the uniformity of the coating appearance (with or without unevenness) was visually evaluated. The evaluation criteria are as follows. ：: uniform appearance without any unevenness △: appearance with some unevenness ×: appearance with unevenness

(2) White Rust Resistance For each sample, salt spray test (JIS-Z-23)
71) was carried out, and evaluated by the area ratio of white rust occurrence after a predetermined time. The evaluation criteria are as follows. ◎: No white rust generated ○ +: White rust generation area ratio less than 5% ○: White rust generation area ratio 5% or more and less than 10% ○-: White rust generation area ratio 10% or more and less than 25% △: White rust Generated area rate 25% or more, less than 50% ×: White rust generated area rate 50% or more

(3) White Rust Resistance After Alkaline Degreasing For each sample, an alkali treatment liquid CLN-364S manufactured by Nippon Parkerizing Co., Ltd. (60 ° C., spray 2
Min), and then a salt spray test (JIS)
-Z-2371), and evaluated by a white rust area ratio after a predetermined time. ◎: No white rust generated ○ +: White rust generation area ratio less than 5% ○: White rust generation area ratio 5% or more and less than 10% ○-: White rust generation area ratio 10% or more and less than 25% △: White rust Generated area rate 25% or more, less than 50% ×: White rust generated area rate 50% or more

(4) Paint Adhesion For each sample, a melamine baking paint (film thickness 30
μm), immersed in boiling water for 2 hours, immediately cut in a grid (10 × 10 grids at 1 mm intervals), adhered and peeled with an adhesive tape, and peeled area of the coating film Rate was evaluated. The evaluation criteria are as follows. ：: No peeling ○: Peeling area rate less than 5% △: Peeling area rate 5% or more, less than 20% ×: Peeling area rate 20% or more

(5) Workability Deep drawing was performed with a blank diameter of φ120 mm and a die diameter of φ50 mm (under no oiling conditions), and evaluated by the molding height until cracks occurred. The evaluation criteria are as follows. ◎: Draw-out ○: Molding height 30 mm or more △: Molding height 20 mm or more, less than 30 mm ×: Molding height less than 20 mm

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

[Table 4]

[0080]

[Table 5]

[0081]

[Table 6]

[0082]

[Table 7]

[0083]

[Table 8]

[0084]

[Table 9]

[0085]

[Table 10]

[0086]

[Table 11]

[0087]

[Table 12]

[0088]

[Table 13]

[0089]

[Table 14]

[0090]

[Table 15]

[0091]

[Table 16]

[0092]

[Table 17]

[0093]

[Table 18]

[0094]

[Table 19]

[0095]

[Table 20]

[0096]

[Table 21]

As a conventional reactive type chromate treated steel sheet,
Chromic anhydride: 30 g / l, phosphoric acid: 10 g / l, Na
F: 0.5 g / l, K ₂ TiF ₆ : Spray treatment at a bath temperature of 40 ° C. using a treatment solution containing 4 g / l, followed by washing and drying to obtain the chromium deposition amount (in terms of chromium metal). Manufactured a chromate-treated steel sheet of 20 mg / m ² . When this was subjected to a salt spray test under the same conditions as in this example, white rust was generated in about 24 hours. Therefore,
From these results and the results of this example, it can be seen that the organic-coated steel sheet of the present invention can provide much better corrosion resistance than the conventional chromate-treated steel sheet.

[0098]

As described above, the organically coated steel sheet of the present invention contains no hexavalent chromium in the processing solution during production or in the film component of the product, and furthermore, the organic coated steel sheet for use in building materials, home appliances, automobiles, etc. It has high corrosion resistance as a steel sheet,
Excellent paint adhesion.

[Table 22]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiko Furuta 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masaru Sagiyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Masaaki Yamashita 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Japan F-term (reference) 4K026 AA02 AA07 AA09 AA12 AA13 AA22 BA01 BA02 BA03 BA12 BB04 BB06 BB08 BB09 CA02 CA16 CA27 CA37 CA38 CA39 CA41 DA15 DA16

Claims (11)

[Claims] 1. An ion-exchanged silica (a) is coated on a surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet with respect to 100 parts by weight (solid content) of a film-forming organic resin (A).
Film thickness containing 0.1 to 100 parts by weight (solid content)
An organic coated steel sheet having excellent corrosion resistance, characterized by having an organic coating of m. 2. An ion-exchange silica (a) and a fine particle silica (b) are coated on the surface of a zinc-based steel sheet or an aluminum-based steel sheet with respect to 100 parts by weight (solid content) of a film-forming organic resin (A). The total content of both is 1 to 100 parts by weight (solid content), and the weight ratio (a) / content of ion exchange silica (a) and fine particle silica (b) (solid content) /
(B) is 1/99 to 99/1, and the film thickness is 0.1 to 5
Organic coated steel sheet with excellent corrosion resistance characterized by having an organic coating of μm. 3. An ion-exchanged silica (a) based on 100 parts by weight (solid content) of a film-forming organic resin (A) is coated on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet.
-100 parts by weight (solid content), 1-8 solid lubricants (c)
An organic coated steel sheet having excellent corrosion resistance, characterized by having an organic film having a thickness of 0.1 to 5 μm containing 0 parts by weight (solid content). 4. An ion-exchanged silica (a) and a fine particle silica (b) are coated on a surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet with respect to 100 parts by weight (solid content) of a film-forming organic resin (A). A total of 1 to 100 parts by weight (solid content), a solid lubricant (c) of 1 to 80 parts by weight (solid content), and a content of ion-exchange silica (a) and fine-particle silica (b) ( An organic coated steel sheet having excellent corrosion resistance, characterized by having an organic coating having a thickness of 0.1 to 5 μm, wherein the weight ratio (a) / (b) of the solid content is 1/99 to 99/1. 5. The organic material having excellent corrosion resistance according to claim 1, wherein the film-forming organic resin (A) is an organic polymer resin having an OH group and / or a COOH group. Coated steel sheet. 6. The organically coated steel sheet having excellent corrosion resistance according to claim 5, wherein the organic polymer resin is a thermosetting resin. 7. The thermosetting resin according to claim 6, wherein the thermosetting resin is an epoxy resin and / or a modified epoxy resin.
Organic coated steel sheet having excellent corrosion resistance according to 1. 8. The zinc-coated steel sheet or the aluminum-coated steel sheet has a chemical conversion coating containing no hexavalent chromium on the surface thereof, and has an organic coating thereon. The organic-coated steel sheet excellent in corrosion resistance according to 4, 5, 6, or 7. 9. The method according to claim 1, wherein the ion exchange silica in the organic film is Ca exchange silica.
The organic-coated steel sheet excellent in corrosion resistance according to 4, 5, 6, 7 or 8. 10. The average particle diameter of the Ca-exchanged silica is 4 μm.
The organic-coated steel sheet excellent in corrosion resistance according to claim 9, characterized in that: 11. A Ca-exchanged silica having a Ca concentration of 2 to 8 watts.
The organic-coated steel sheet excellent in corrosion resistance according to claim 9 or 10, wherein the content is t%.