JP2005288732A - Non-weldable organic coated steel sheet for automobile excellent in corrosion resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic coated steel sheet for an automobile showing excellent corrosion resistance containing no chromium in a film and excellent in processability or the like. <P>SOLUTION: A film, which is an organic film, an inorganic film or an organic/inorganic composite film containing no chromium and has a reaction film with a plating metal, is formed on the surface of a zinc or aluminum plated steel sheet in a specific film thickness and an organic/inorganic composite film, which contains 1-120 pts.mass of a rustproofing additive containing no chromium and 0.1-20 pts.mass of a solid lubricant with respect to 100 pts.mass of an organic resin, is formed on the film in specific film thickness. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-welded organic coated steel sheet for automobiles used in automobile parts and automobile bodies (including replacement repair parts). For example, in an automobile manufacturer, (1) omission of a chemical conversion treatment process, ( 2) Omission of chemical conversion treatment process and electrodeposition coating process, (3) Reduction of electrodeposition film thickness in electrodeposition coating process, (4) Omission or reduction of secondary materials (sealer, wax), etc. A coated steel sheet is provided.

  Conventionally, in the field of building materials, painted steel plates such as colored zinc iron plates and colored steel plates have been used for roofing materials and wall materials. In the consumer electronics industry, where strict performance is required for product design, it was triggered by the adoption of pre-coated steel sheets (PCM) in refrigerators by US consumer electronics manufacturers. Pre-coated steel sheet is applied. Pre-coating is a method in which the surface of a steel plate (strip) is coated in advance by a method such as roll coating or powder coating, and processing and assembly are performed using this coated steel plate. For the method of painting after processing, the benefits of cost reduction and environmental measures can be expected by omitting the pretreatment and painting process by the user.

On the other hand, in the field of automobiles, corrosion of automobile bodies due to road freezing prevention salts sprayed in winter in cold regions such as North America and Northern Europe has become a major social problem, and rust prevention measures for the automobile bodies have been strengthened.
Conventionally, as a rust-proof steel plate for automobiles, a rust-proof coated steel plate (zinc metal) having a zinc powder-containing coating film formed with a film thickness of 10 to 20 μm, such as Patent Document 1, has been used. However, the coating film containing zinc powder of this rust-prevention coated steel sheet shows significant peeling of the film during press molding, which not only causes accumulation of defects and press cracks in the mold, but also the part where the rust-proof coating peels off. There was a problem that the corrosion resistance of the deteriorated.

  In recent years, it can be said that the need for rust prevention is almost satisfied by the remarkable progress of quality performance such as rust prevention and workability of galvanized steel sheet. On the other hand, recently, in manufacturing processes at automakers, there is a need to reduce total costs by reducing and omitting secondary materials such as sealers and waxes, reducing film thickness of electrodeposition coating, shortening and omitting chemical conversion treatment and electrodeposition processes. Is growing. European automakers have already formed a chromate film on the surface of galvanized steel sheets with the aim of reducing and omitting secondary materials such as sealers and waxes, and further containing conductive metal powders such as zinc powder. There are cases in which an organic coated steel sheet having a coating film of a certain degree is employed. However, the fact that it is necessary to perform a chromate treatment containing hexavalent chromium, the problem of peeling of the film during press working, and the problem of corrosion resistance after peeling is not actually solved.

  Recently, as rust-proof steel plates applied to automobiles and the like, for example, those shown in Patent Documents 2 to 5 have been proposed, and Patent Document 6 discloses phosphoric acid on the surface of a zinc-based alloy-plated steel sheet. A rust-proof steel sheet is shown in which a chemical conversion treatment mainly composed of a compound is performed and an organic coating film composed of an organic resin, a conductive pigment and a rust-proof pigment is formed on the surface thereof.

Japanese Patent Publication No. 47-6882 Japanese Patent Laid-Open No. 10-44307 Japanese Patent Laid-Open No. 9-276785 Japanese Patent Laid-Open No. 10-043677 JP-A-10-128906 JP-A-9-277438

However, since the rust-proof steel sheets of Patent Documents 2 to 5 are all subjected to chromate treatment or use hexavalent chromium-based rust-proof pigments, there are problems in terms of the environment. In addition, since the rust-proof steel sheet of Patent Document 6 has been subjected to a conventional crystalline phosphate treatment as a chemical conversion treatment, not only processability cannot be expected, but also a hexavalent chromic acid type as a rust-proof pigment. The use of anti-corrosive pigments also has environmental problems.
Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an organic coated steel sheet for automobiles which exhibits excellent corrosion resistance without containing chromium in the film, and which is excellent in workability and the like. There is.

In order to solve the above problems, the non-welded organic coated steel sheet for automobiles of the present invention has the following characteristics.
[1] On the surface of zinc-plated steel sheet or aluminum-plated steel sheet,
As the first layer film, an organic film or an inorganic film or an organic-inorganic composite film that does not contain chromium, and a film having a reaction layer with a plating metal is formed with a film thickness of 0.01 to 3 μm,
An organic-inorganic composite film containing 1 to 120 parts by mass of a rust preventive additive not containing chromium and 0.1 to 20 parts by mass of a solid lubricant with respect to 100 parts by mass of an organic resin as a second layer film. Is formed with a film thickness of 1 to 30 μm, and is a non-welded organic coated steel sheet for automobiles excellent in corrosion resistance.

[2] The non-welded organic coated steel sheet for automobiles excellent in corrosion resistance, characterized in that the first layer coating contains an anticorrosive additive not containing chromium in the organic coated steel sheet of [1].
[3] A non-weld type organic coated steel sheet for automobiles having excellent corrosion resistance, wherein the first layer coating contains an amorphous phosphate compound in the organic coated steel sheet of [1] or [2].
[4] In the organic coated steel sheet according to any one of [1] to [3], the first layer film is an epoxy resin, a modified epoxy resin, a polyhydroxy polyether resin, a polyalkylene glycol modified epoxy resin, a urethane modified epoxy resin. A non-welded organic coating for automobiles having excellent corrosion resistance, comprising at least one selected from phenolic resins, modified phenolic resins, polyhydric phenol derivatives, and resins obtained by further modifying these resins steel sheet.

[5] In the organic coated steel sheet according to any one of [1] to [4], the organic resin of the second layer film is an epoxy resin, a modified epoxy resin, a polyhydroxy polyether resin, a polyalkylene glycol-modified epoxy resin, urethane Non-weld for automobiles with excellent corrosion resistance, characterized by being at least one selected from modified epoxy resins, resins obtained by further modifying these epoxy resins, polyester resins, urethane resins, silicone resins, and acrylic resins Type organic coated steel sheet.
[6] In the organic coated steel sheet according to any one of [1] to [5], the rust preventive additive not containing chromium is at least one selected from the following (e1) to (e7): Non-welded organic coated steel sheet for automobiles with excellent corrosion resistance.
(E1) calcium or / and calcium compounds (e2) silicon oxide (e3) sparingly soluble phosphate compounds (e4) molybdate compounds (e5) vanadium compounds (e6) triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

  The organic coated steel sheet for automobiles of the present invention exhibits excellent corrosion resistance despite the fact that it does not contain chromium in the film, and also exhibits excellent performance such as workability.

  The organic coated steel sheet for automobiles of the present invention is an organic film, inorganic film or organic-inorganic composite film that does not contain chromium as the first layer film on the surface (one side or both sides) of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. Then, a film having a reaction layer with the plating metal is formed with a film thickness of 0.01 to 3 μm, and the second layer film is formed thereon as a second layer film, and 100 parts by mass of the organic resin does not contain chromium. 1 to 120 parts by mass and an organic-inorganic composite film containing 0.1 to 20 parts by mass of a solid lubricant with a film thickness of 1 to 30 μm. The organic coated steel sheet for automobiles of the present invention is a non-welded type that does not assume spot welding, and is joined by a joining method other than spot welding when used.

The details of the present invention and the reasons for limitation will be described below.
Examples of the zinc-based plated steel sheet used as the base of the organic coated steel sheet of the present invention include a galvanized steel sheet, a Zn-Ni alloy-plated steel sheet, a Zn-Fe alloy-plated steel sheet (electroplated steel sheet, galvannealed steel sheet), Zn-Cr. Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-Co 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 plating Steel plate (for example, Zn-5% Al alloy-plated steel plate, Zn-55% Al alloy-plated steel plate), Zn-Mg alloy-plated steel plate, Zn-Al-Mg-plated steel plate (for example, Zn-6% Al-3% Mg alloy) Plated steel sheet, Zn-11% Al-3% Mg alloy-plated steel sheet), and further, metal oxides, polymers, etc. were dispersed in the plating film of these plated steel sheets Lead-based composite plated steel sheets (for example, Zn-SiO ₂ dispersion plating steel plate) or the like can be used.
In addition, among the above-described plating, a multi-layer plated steel sheet in which two or more layers of the same type or different types are plated can also be used.

In addition, as the aluminum-based plated steel sheet that is 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.
Moreover, as a plated steel plate, the steel plate surface may be previously plated with lightness such as Ni, and various plating as described above may be performed thereon.
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a nonaqueous solvent), a melting method, and a vapor phase method can be adopted.
Furthermore, for the purpose of preventing blackening of the plating, about 1 to 2000 ppm of trace elements of Ni, Co, and Fe are deposited in the plating film, or an alkaline aqueous solution or acid solution containing Ni, Co, Fe on the surface of the plating film. You may make it surface-treat with an aqueous solution and precipitate these elements.

Next, the first layer film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet will be described.
This first layer film is an organic film, an inorganic film or an organic-inorganic composite film that does not contain chromium, and a reaction layer with the plating metal reacts with the interface with the plating surface, that is, the plating metal and the film forming component react. The reaction layer is formed. The function of this film is to ensure strong adhesion to the plating surface (plating metal) and to suppress corrosion of the plating metal at the interface.

  The first layer film may be any of an inorganic film, an organic film, and an organic-inorganic composite film. Examples of the inorganic film include a film containing, as a main component, one or more of a phosphoric acid compound, a metal salt, an oxide, an etching agent (such as fluoride), and the like. Moreover, as an organic membrane | film | coat, the membrane | film | coat which has organic resin, an organic acid, etc. as a main component is mentioned. Examples of the organic / inorganic composite coating include a coating mainly composed of one or more inorganic components such as a water-based organic resin, a phosphoric acid compound, a metal salt, an oxide, and an etching agent (fluoride). However, in consideration of severe press working as a steel sheet for automobiles, an organic film or an organic-inorganic composite film is preferable. In particular, from the viewpoint of corrosion resistance, the organic resin may be an epoxy resin, a modified epoxy resin, Contains one or more selected from hydroxy polyether resins, polyalkylene glycol-modified epoxy resins, urethane-modified epoxy resins, phenol resins, modified phenol resins, polyphenol derivatives, and resins obtained by further modifying these resins It is preferable.

In the present invention, the first layer coating is required to have a reaction layer when the treatment composition reacts with the plating metal. The purpose of forming this reaction layer is (1) deactivation of the plating film surface, (2) strengthening adhesion at the plating film / first layer film interface, and (3) corrosion reaction at the same interface. It is in the point of suppressing. For this reason, it is particularly desirable to add a phosphoric acid compound to the treatment composition.
The first layer film preferably contains an amorphous phosphoric acid compound in order to appropriately form the reaction layer and to obtain the following effects. This amorphous phosphate compound functions effectively to ensure the adhesion between the plating surface and the coating, and the soluble phosphoric acid in the coating captures zinc and aluminum to suppress the occurrence of white rust. There is an effect to. A phosphoric acid compound (crystallinity) produced by a conventional phosphate treatment is not preferable because of poor processability.

For the purpose of improving the corrosion resistance, a rust preventive additive not containing chromium (non-chromium rust preventive additive) can be added to the first layer film. As the non-chromium rust preventive additive, it is particularly preferable to use one or more selected from the following (e1) to (e7).
(E1) Calcium and / or calcium compounds (e2) Silicon oxide (e3) Slightly soluble phosphate compounds (e4) Molybdate compounds (e5) Vanadium compounds (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

The anticorrosion mechanism obtained by these anticorrosive additives will be described in the configuration of the second layer coating, but by adding such an anticorrosive additive into the first layer coating, excellent anticorrosion performance ( Self-repairability).
The compounding amount of the rust preventive additive is suitably 1 to 100 parts by mass, preferably 10 to 80 parts by mass with respect to 100 parts by mass of the solid content of the first layer film. If the blending amount of this non-chromium rust preventive additive is less than 1 part by mass, the effect of improving the corrosion resistance after alkali degreasing resistance cannot be sufficiently obtained. On the other hand, if it exceeds 100 parts by mass, the paintability and workability only deteriorate. Moreover, since corrosion resistance also falls, it is not preferable.
The film thickness of the first layer film is 0.01 to 3 μm. If the film thickness is less than 0.01 μm, sufficient corrosion resistance cannot be improved. On the other hand, if it exceeds 3 μm, the powdering resistance is significantly lowered.

Next, the second layer coating formed on the first layer coating will be described.
This second layer film contains an organic resin, an antirust additive not containing chromium (non-chromium antirust additive), and a solid lubricant as essential components.
Examples of organic resins include epoxy resins, modified epoxy resins, polyhydroxy polyether resins, polyalkylene glycol-modified epoxy resins, urethane-modified epoxy resins, resins obtained by further modifying these epoxy resins, polyester resins, urethane resins, silicon resins It is preferable to use one or more selected from acrylic resins. In particular, from the viewpoint of corrosion resistance, it is desirable to use an epoxy resin as a base and appropriately optimize the molecular weight for the purpose of improving processability.

By including a non-chromium rust preventive additive in the second layer coating, excellent anticorrosion performance (self-repairability) can be obtained.
As this rust preventive additive, it is particularly preferable to use one or more selected from the following (e1) to (e7).
(E1) calcium or / and calcium compounds (e2) silicon oxide (e3) sparingly soluble phosphate compounds (e4) molybdate compounds (e5) vanadium compounds (e6) triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

The details and anticorrosion mechanism of the non-chromium rust preventive additives (e1) to (e7) are as follows.
The calcium compound as the component (e1) may be any of calcium oxide, calcium hydroxide, and calcium salt, and one or more of these can be used. In addition, there are no particular restrictions on the type of calcium salt. In addition to simple salts containing only calcium as a cation such as calcium silicate, calcium carbonate, and calcium phosphate, calcium and calcium such as calcium phosphate / zinc, calcium phosphate / magnesium, etc. Double salts containing other cations may be used. The components (e1) is baser calcium than zinc and aluminum as the plating metal in a corrosive environment is preferentially dissolved, this OH produced by the cathode reaction ^- sequestering defective portion as a product of dense and poorly soluble And suppress the corrosion reaction. Further, when compounded with silica as described below, calcium ions are adsorbed on the surface, and the surface charge is electrically neutralized and aggregated. As a result, a dense and hardly soluble protective film is formed to block the corrosion and suppress the corrosion reaction.

As the component (e2), colloidal silica or dry silica, which is fine particle silica, can be used. From the viewpoint of corrosion resistance, it is desirable to use calcium ion exchange silica in which calcium is bound to the surface thereof. .
As colloidal silica, for example, SNOWTEX O, 20, 30, 40, C, S (all trade names) manufactured by Nissan Chemical Co., Ltd. can be used, and as fumed silica, Nippon Aerosil ( AEROSIL R971, R812, R811, R974, R202, R805, 130, 200, 300, 300CF (all trade names) manufactured by Co., Ltd. can be used. In addition, as calcium ion exchange silica, WRGrace & Co. SHIELDEX C303, SHIELDEX AC3, SHIELDEX AC5 (all are trade names) manufactured by SHIELDEX, SHIELDEX, SHIELDEX SY710 (all are trade names) manufactured by Fuji Silysia Chemical Co., Ltd., and the like can be used. These silicas contribute to the formation of a dense and stable corrosion product of a plated metal in a corrosive environment, and the corrosion product is densely formed on the plating surface, thereby suppressing the promotion of corrosion.

  Further, as the hardly soluble phosphate compound (e3), a hardly soluble phosphate can be used. This sparingly soluble phosphate includes all types of salts such as simple salts and double salts. Moreover, there is no limitation in the metal cation which comprises it, and any metal cation, such as poorly soluble zinc phosphate, magnesium phosphate, calcium phosphate, aluminum phosphate, may be sufficient. Further, there is no limitation on the skeleton or the degree of condensation of phosphate ions, and any of normal salt, dihydrogen salt, monohydrogen salt or phosphite may be used. In addition to orthophosphate, the normal salt may be polyphosphate. Includes all condensed phosphates such as salts. By using this hardly soluble phosphorus compound, zinc and aluminum of the plating metal eluted by corrosion undergo a complex formation reaction with phosphate ions dissociated by hydrolysis, thereby producing a dense and hardly soluble protective film. Blocks corrosion starting points and suppresses corrosion reactions.

As the molybdate compound (e4), for example, molybdate can be used. The molybdate is not limited in its skeleton and degree of condensation, and examples thereof include orthomolybdate, paramolybdate, and metamolybdate. Moreover, all salts, such as a single salt and a double salt, are included, and phosphoric acid molybdate etc. are mentioned as a double salt. Molybdate compounds exhibit self-repairing properties due to the passivating effect. That is, by forming a dense oxide on the plating film surface together with dissolved oxygen in a corrosive environment, the corrosion starting point is blocked and the corrosion reaction is suppressed.
As the vanadium compound (e5), for example, a pentavalent vanadium compound or a tetravalent vanadium compound can be applied. In particular, a tetravalent vanadium compound is preferable from the viewpoint of corrosion resistance.

  Examples of the organic compound (e6) include the following. That is, as triazoles, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2 1,4-triazole, 1H-benzotriazole, etc., and as thiols, 1,3,5-triazine-2,4,6-trithiol, 2-mercaptobenzimidazole, etc., and as thiadiazoles, 5- Amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole and the like, and as thiazoles, 2-N, N-diethylthiobenzothiazole, 2-mercapto Examples include benzothiazoles, and examples of thiurams include tetraethylthiuram disulfide. It is. These organic compounds exhibit self-repairing properties due to the adsorption effect. That is, zinc and aluminum eluted by corrosion are adsorbed on polar groups containing sulfur contained in these organic compounds to form an inert film, thereby blocking the corrosion starting point and suppressing the corrosion reaction.

  Examples of the organic compound (e7) include the following. That is, hydrazide compounds include carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenone. , Aminopolyacrylamide, etc .; as pyrazole compounds, pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole, etc .; as triazole compounds, 1,2,4-triazole 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2, -Triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6-methyl-8-hydroxytriazolopyridazine, 6 -Phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine, etc .; tetrazole compounds include 5-phenyl-1,2,3,4-tetrazole, 5 -Mercapto-1-phenyl-1,2,3,4-tetrazole and the like; As thiadiazole compounds, 5-amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4 -Thiadiazole and the like; as pyridazine compounds, maleic hydrazide, 6-methyl-3-pyridazone, 4, - dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, such as 6-methyl-4,5-dihydro-3-pyridazone and the like. Of these, pyrazole compounds and triazole compounds having a 5- or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.

Two or more rust preventive additives (e1) to (e7) may be added in combination. In this case, since the inherent anticorrosive action is combined, higher corrosion resistance can be obtained. In particular, calcium ion-exchanged silica is used as the component (e1) and one or more of the components (e3), (e4), (e5), (e6), and (e7) are used, particularly preferably (e3 Particularly excellent corrosion resistance can be obtained when all of the components (e) to (e7) are added in combination.
The compounding amount of the non-chromium rust preventive additive in the second layer coating is 1 to 120 parts by mass, preferably 10 to 50 parts by mass with respect to 100 parts by mass (solid content) of the organic resin. If the compounding amount of the rust preventive additive is less than 1 part by mass with respect to 100 parts by mass of the organic resin, the effect of improving the corrosion resistance is not sufficient. On the other hand, if it exceeds 120 parts by mass, the corrosion resistance is lowered and the powdering resistance Is also inferior.

A solid lubricant is blended in the second layer coating for the purpose of improving the workability of the coating. Examples of the solid lubricant include the following, and one or more of them can be used.
(1) Polyolefin wax, paraffin wax: For example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc. (2) Fluorine resin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.) In addition, fatty acid amide compounds (eg, stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, oleic acid amide, esyl) Acid amides, alkylene bis fatty acid amides, etc.), metal soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal sulfides (eg, molybdenum disulfide, tungsten disulfide, etc.) ), Graphite, fluorinated graphite, boron nitride, polyalkylene glycol, alkali metal sulfate, or the like may be used.

Among the above solid lubricants, polyethylene wax and fluororesin fine particles (in particular, polytetrafluoroethylene resin fine particles) are preferable.
Examples of polyethylene waxes include Hoechst's Selidust 9615A, Selidust 3715, Selidust 3620, Selidust 3910 (all trade names), Sanyo Kasei Sun Wax 131-P, Sun Wax 161-P (all trade names) ), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (all trade names) manufactured by Mitsui Petrochemical Co., Ltd. can be used.

The fluororesin fine particles are most preferably tetrafluoroethylene fine particles. For example, Lubron L-2 and Lubron L-5 (both trade names) manufactured by Daikin Industries, Ltd., MP1100 and MP1200 manufactured by Mitsui / DuPont (all Are also trade names), full-on dispersion AD1, full-on dispersion AD2, full-on L141J, full-on L150J, and full-on L155J (all trade names) manufactured by Asahi IC Fluoropolymers.
Among these, a particularly excellent lubricating effect can be expected by the combined use of polyolefin wax and tetrafluoroethylene fine particles.
The blending amount of the solid lubricant in the second layer film is 0.1 to 20 parts by mass (solid content), preferably 1 to 10 parts by mass (solid content) with respect to 100 parts by mass (solid content) of the organic resin. ). When the blending amount of the solid lubricant is less than 0.1 parts by mass, the lubrication effect is poor. On the other hand, when the blending amount exceeds 20 parts by mass, the paint adhesion is deteriorated.

In the second layer film, other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate (for example, phosphomolybdic acid) are used as corrosion inhibitors. Aluminum), organic phosphoric acid and salts thereof (eg, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts thereof, alkali metal salts, alkaline earth metal salts, etc.), organic inhibitors (eg, One or more of hydrazine and its derivatives, thiol compounds, thiocarbamates, etc.) can be added.
Further, as necessary, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.) 1 such as inorganic pigment (for example, titanium oxide), metal powder, chelating agent (for example, thiol), coupling agent (for example, silane coupling agent, titanium coupling agent), melamine cyanuric acid adduct, etc. More than seeds can be added.

The film thickness of the second layer film is 1 to 30 μm. If the film thickness is less than 1 μm, sufficient corrosion resistance cannot be improved. On the other hand, if the film thickness exceeds 30 μm, the post-processing corrosion resistance and powdering resistance are poor.
The organic-coated steel sheet of the present invention described above is obtained by applying a treatment composition for forming a first layer film (preferably a treatment composition containing a phosphate compound) to the surface of a galvanized steel sheet or an aluminum-coated steel sheet. The composition for forming the second layer film can be applied and dried by heating in a heating furnace or the like.

For forming the first layer, the components shown in Table 2 were blended and stirred for a predetermined time using a paint disperser (sand grinder) to prepare a surface treatment composition. In addition, these surface treatment compositions are compounded so that a reaction layer is formed at the interface between the plating metal and the first layer film.
As the coating composition for forming the second layer, the resin composition shown in Table 3 is used, and a non-chromium rust preventive additive (Table 4) and a solid lubricant (Table 5) are appropriately blended into the coating composition. The mixture was stirred for a predetermined time using a dispersing machine (sand grinder) to prepare a coating composition.

The plated steel sheet shown in Table 1, which is a plated steel sheet for home appliances, building materials, and automobile parts based on cold-rolled steel sheets, was used as a processing original sheet. In addition, the thing of predetermined | prescribed board thickness was employ | adopted for the board thickness of the steel plate according to the objective of evaluation. After the surface of this plated steel sheet was subjected to alkali degreasing treatment, washed with water and dried, the surface treatment composition for forming the first layer was applied with a roll coater and dried by heating at various temperatures. The film thickness of the first layer film was adjusted by the solid content (heating residue) of the surface treatment composition or coating conditions (rolling force of the roll, rotation speed, etc.).
Next, the coating composition for forming the second layer was applied by a roll coater and dried by heating at various temperatures. The film thickness of the second layer film was adjusted by the solid content (heating residue) of the coating composition or the coating conditions (roll rolling force, rotational speed, etc.).
Tables 6 to 13 show the results of evaluating the coating composition and quality performance (corrosion resistance, post-processing corrosion resistance, weldability, powdering resistance, paint adhesion) of the obtained organic coated steel sheet. The quality performance was evaluated as follows.

(1) Corrosion resistance About each sample, after degreasing on condition of 60 ° C. × 2 minutes using “FC-4460” manufactured by Nippon Parkerizing Co., Ltd., the following combined cycle test (CCT) was performed, and after 36 cycles The white rust generation area ratio and the red rust generation area ratio were evaluated.
Salt spray (based on JIS Z 2371): 4 hours ↓
Dry (60 ° C): 2 hours ↓
Wet (50 ° C., 95% RH): 2 hours The evaluation criteria are as follows.
◎: White rust generation area ratio less than 5% ○ +: White rust generation area ratio 5% or more, less than 10% ○: White rust generation area ratio 10% or more, less than 30% ○-: White rust generation area ratio 30% or more No red rust occurrence △: Red rust occurrence, red rust occurrence area ratio less than 10% ×: Red rust occurrence area ratio 10% or more

(2) Corrosion resistance after processing For each sample, deformation and sliding were added with a draw bead under the following conditions, and this sample was used at 60 ° C. × 2 minutes using “FC-4460” manufactured by Nihon Parkerizing Co., Ltd. After degreasing under the conditions, the CCT performed in “(1) Corrosion resistance” was performed, and the white rust generation area ratio and red rust generation area ratio after 18 cycles were evaluated.
Pressing load: 800kgf
Drawing speed: 1000mm / min
Bead shoulder R: Male side 2mmR, Female side 3mmR
Pushing depth: 7mm
Oil used: “Preton R-352L” manufactured by Sugimura Chemical Co., Ltd.
The evaluation criteria are as follows.
◎: White rust generation area ratio less than 5% ○ +: White rust generation area ratio 5% or more, less than 10% ○: White rust generation area ratio 10% or more, less than 30% ○-: White rust generation area ratio 30% or more No red rust occurrence △: Red rust occurrence, red rust occurrence area ratio less than 10% ×: Red rust occurrence area ratio 10% or more

(3) A powder bead tip diameter of 0.5 mmR, a bead height of 4 mm, a drawing speed of 200 mm / min, a pressure bead of 500 kgf, a sample is subjected to a draw bead test, and an adhesive tape is adhered to and peeled from a sliding portion. The difference in weight of the sample before and after the test was measured, and this was converted per unit area and evaluated as follows.
◎: 5g / ^{m 2} following 〇: 5g / ^{m 2} greater than, 7g / ^{m 2} following 〇-: 7g / ^{m 2} greater than, 10g / ^{m 2} or less △: 10g / ^{m 2} greater than, 20g / ^{m 2} or less ×: 20g / M ²

(4) Paint adhesion The surface of each sample was coated with an intermediate coating “KPX-36” (film thickness: 40 μm) manufactured by Kansai Paint Co., Ltd., followed by “Lugabake B-531” manufactured by Kansai Paint Co., Ltd. The top coat (film thickness 40 μm) was applied. After immersing this sample in ion exchange water at 40 ° C. for 240 hours, the sample was taken out and allowed to stand at room temperature for 24 hours. 100 grids at intervals of 2 mm were cut into the coating film of this sample, the adhesive tape was adhered and peeled, and the peeled area ratio of the coating film was evaluated. The evaluation criteria are as follows.
◎: No peeling of coating film ◯: Less than 3% coating film peeling area ratio △: 3% or more coating film peeling area ratio less than 10% ×: 10% or more coating film peeling area ratio

In addition, * 1 to * 6 described in Tables 6 to 13 indicate the following contents.
* 1: No. described in Table 1. (Plated steel plate)
* 2: No. in Table 2 (Surface treatment composition for forming the first layer film)
* 3: No. described in Table 3 (Resin composition for forming the second layer film)
* 4: No. in Table 4 (Anti-rust additive for second layer coating)
* 5: No. in Table 5 (Solid lubricant for second layer coating)
* 6: Mass part

Claims (6)

On the surface of zinc-based plated steel sheet or aluminum-based plated steel sheet,
As the first layer film, an organic film or an inorganic film or an organic-inorganic composite film that does not contain chromium, and a film having a reaction layer with a plating metal is formed with a film thickness of 0.01 to 3 μm,
An organic-inorganic composite film containing 1 to 120 parts by mass of a rust preventive additive not containing chromium and 0.1 to 20 parts by mass of a solid lubricant with respect to 100 parts by mass of an organic resin as a second layer film. Is formed with a film thickness of 1 to 30 μm, and is a non-welded organic coated steel sheet for automobiles excellent in corrosion resistance.   The non-welded organic coated steel sheet for automobiles with excellent corrosion resistance according to claim 1, wherein the first layer film contains a rust preventive additive not containing chromium.   The non-welded organic coated steel sheet for automobiles with excellent corrosion resistance according to claim 1 or 2, wherein the first layer film contains an amorphous phosphate compound.   First layer coating further modifies epoxy resin, modified epoxy resin, polyhydroxy polyether resin, polyalkylene glycol modified epoxy resin, urethane modified epoxy resin, phenol resin, modified phenol resin, polyhydric phenol derivative, and these resins The non-welded organic coated steel sheet for automobiles having excellent corrosion resistance according to any one of claims 1 to 3, comprising at least one selected from the resins made.   The organic resin of the second layer film is epoxy resin, modified epoxy resin, polyhydroxy polyether resin, polyalkylene glycol modified epoxy resin, urethane modified epoxy resin, resin obtained by further modifying these epoxy resins, polyester resin, urethane The non-welded organic coated steel sheet for automobiles having excellent corrosion resistance according to any one of claims 1 to 4, which is at least one selected from a resin, a silicon resin, and an acrylic resin. The rust preventive additive not containing chromium is at least one selected from the following (e1) to (e7), and has excellent corrosion resistance for automobiles according to any one of claims 1 to 5. Non-welded organic coated steel sheet.
(E1) calcium or / and calcium compounds (e2) silicon oxide (e3) sparingly soluble phosphate compounds (e4) molybdate compounds (e5) vanadium compounds (e6) triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds