JP4892433B2 - Method for forming surface treatment film - Google Patents

Description

  The present invention relates to a method for forming a surface-treated film excellent in corrosion resistance of a film and stability of a film forming agent, a film structure formed by the method, and a coated article.

  Conventionally, an industrial metal substrate has been subjected to zinc phosphate treatment as a ground treatment for the purpose of improving corrosion resistance and adhesion. However, the chemical conversion treatment with a zinc phosphate treatment agent contains a large amount of phosphorus and nitrogen in the treatment agent, and contains a large amount of heavy metals such as nickel and manganese in order to improve the performance of the formed chemical conversion film. Therefore, there is a problem in the treatment of industrial waste, etc. due to environmental impact and a large amount of sludge such as zinc phosphate and iron phosphate after treatment.

  In addition, in order to improve the corrosion resistance of industrial metal substrates, a lot of space and time are required for processing steps such as “degreasing—surface conditioning—chemical conversion treatment—electrodeposition coating” in the coating line.

  Patent Document 1 proposes a chemical conversion treatment agent for iron and / or zinc-based substrates that contains substantially no phosphate ions and contains zirconium ions and / or titanium ions and fluorine ions. However, the chemical conversion treatment agent for iron and / or zinc-based substrate described in Patent Document 1 has a problem that sufficient anticorrosion and finishing properties cannot be secured unless a coating film is applied by a coating process after the treatment.

  Patent Document 2 describes (A) a compound containing at least one metal element selected from Ti, Zr, Hf, and Si, and (B) a surface treatment of a metal containing a fluorine-containing compound as a supply source of fluorine ions. By using the composition, a surface treatment film having excellent corrosion resistance can be deposited on the surface of a metal containing at least one of iron and zinc, and no surface adjustment (surface tone) step is required. It is disclosed to shorten and save space. However, the composition for surface treatment described in Patent Document 2 also has a problem that sufficient anticorrosion properties and finish properties cannot be secured unless a coating film is applied by a coating process after the treatment.

  Patent Document 3 and Patent Document 4 include at least one selected from (A) amine-modified acrylic resin, (B) phosphoric acid compound, hydrofluoric acid, metal hydrofluoric acid, and metal hydrofluoride. Press formability and corrosion resistance by covering a zinc-plated steel sheet used for automobile bodies, home appliances, etc., containing at least one compound selected from a compound, (C) molybdenum compound, tungsten compound and vanadium compound A surface treatment composition for a lubricated steel sheet capable of obtaining an excellent lubricated steel sheet is disclosed. However, steel sheets that have been surface-treated with the surface treatment composition for lubricating steel sheets described in Patent Document 3 and Patent Document 4 ensure sufficient anticorrosion and finish unless a coating film is applied by a coating process after chemical conversion treatment. Therefore, it is impossible to shorten the process and save space.

  Patent Document 5 discloses a polymer composition for a metal surface treatment agent comprising a specific copolymer having a salicylideneamino group and an amino group. However, the steel sheet treated with the polymer composition for a metal surface treating agent described in Patent Document 5 is also unable to ensure sufficient anticorrosiveness and finish without applying a coating film by a coating process. Shortening and space saving cannot be achieved.

Patent Document 6 discloses a method of forming a coating film by cation electrodeposition coating of a multistage energization method in a gap portion of an object having a complicated structure such as an automobile body having a gap of 500 μm or less. . The multi-stage energization method described in Patent Document 6 is effective to improve the anticorrosion property by covering the gap portion of the object having a gap of 500 μm or less, but can secure sufficient anticorrosion property and finish. It has not yet reached.

  Further, in Patent Document 7 (European Patent Publication No. 1342758), a cationic electrodeposition coating containing a plurality of emulsions with a constant difference in the amount of electricity required for the start of deposition is applied by a multistage energization method. Although a method for forming a multilayer electrodeposition coating film is disclosed, sufficient corrosion resistance is not achieved by this method.

JP 2003-155578 A International Publication No. 02/103080 Pamphlet JP 2003-166073 A JP 2003-226882 A JP 2003-293161 A JP-A-2-282499 JP 2003-328192 A

  The objective of this invention is providing the formation method of the surface treatment film | membrane excellent in the corrosion resistance of a film | membrane and the stability of a film formation agent.

  As a result of extensive research, the present inventor has found that the above object can be achieved by applying a specific film-forming agent to a metal substrate under a specific condition by a multi-stage energization method. The invention has been completed.

Thus, the present invention is a method of forming a film on a metal substrate by coating a film forming agent in at least two stages of multi-stage energization methods,
(I) The film forming agent is composed of a zirconium compound and, if necessary, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, aluminum, bismuth, yttrium, lanthanoid metal, alkali metal, and alkaline earth metal. A compound containing at least one selected metal (a) in a total metal amount (in terms of mass) of 30 to 20,000 ppm, and an anionic group-containing resin component 1 to 40% by mass,
(Ii) First stage coating was performed by energizing for 10 to 360 seconds at a voltage of 1 to 50 V with the metal substrate as a cathode in a state where the metal substrate was immersed in the film forming agent, and (iii) metal A surface-treated film characterized by performing the second and subsequent coatings by applying current for 60 to 600 seconds at a voltage of 50 to 400 V using a metal substrate as an anode while the substrate is immersed in a film forming agent. A forming method is provided.

  The present invention also contains a zirconium compound and a metal (a) -containing compound in a total metal amount (in terms of mass) of 25 to 100% by mass based on the total mass solid content of the film formed by the above method. Based on the total mass solid content of the film on the film (X) having a thickness of 0.01 to 5 μm and the film (X), the zirconium compound and the metal (a) -containing compound are converted into a total metal amount (in terms of mass) ) And a coating structure comprising a coating (Y) having a thickness of 0.1 to 30 μm and containing less than 25 mass% and containing 50 to 95 mass% of an anionic group-containing resin component.

  The surface treatment film formed by the method of the present invention is excellent in corrosion resistance. Moreover, the film-forming agent used in the method of the present invention is excellent in stability, and the anticorrosion property does not change even when used in an industrial line for a long time.

The reason why the film structure formed by the method of the present invention is excellent in anticorrosiveness is not exactly known, but the film (X) deposited on the coated side contributes to the suppression of undercoat corrosion and is thick. It is considered that the film (Y) having a thickness of 0.1 to 30 μm has a function sharing in the film structure to block the finish and corrosion promoting substances (for example, O ₂ , Cl ⁻ , Na ⁺ ). It is done.

  Hereinafter, the method for forming the surface treatment film of the present invention will be described in more detail.

BEST MODE FOR CARRYING OUT THE INVENTION

  In the present invention, a specific “film forming agent” is used on a metal substrate to form a surface-treated film by a “two-stage or more multi-stage energization method” under specific conditions.

Film forming agent :
The film-forming agent used in the method of the present invention comprises a zirconium compound and, if necessary, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, aluminum, bismuth, yttrium, lanthanoid metals (lanthanum, cerium, Praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium), alkali metals (lithium, sodium, potassium, rubidium, cesium, francium) and alkaline earth metals (beryllium, magnesium, A metal compound component (A) composed of a compound containing at least one metal (a) selected from calcium, strontium, barium and radium) And 30~20,000ppm San), those comprising an anionic group-containing resin component (B) 1 to 40 wt%.

Metal compound component (A) :
In the first-stage coating according to the present invention, the metal ions generated from the metal compound component (A) are precipitated on the surface of the metal substrate by a multi-stage energization method of two or more stages, and in some cases further with the zirconium compound. A film (X) containing the metal (a) -containing compound is formed. In addition, when using together a zirconium compound and a metal (a) containing compound, it can replace with this combination and can use the compound in which a zirconium and a metal (a) coexist in a single compound, and metal (A) When two or more kinds of metal (a) -containing compounds are used in combination as the containing compound, a compound in which two or more kinds of metals (a) coexist in a single compound is used instead of the combination. It can also be used.

  The zirconium compound used in the metal compound component (A) is a zirconium-containing compound that generates zirconium-containing ions such as zirconium ions, oxyzirconium ions, and fluorozirconium ions when energized during coating, and is a compound that generates oxyzirconium ions. Is, for example, zirconyl nitrate, zirconyl acetate, zirconyl sulfate, etc .; examples of the compound that produces fluorozirconium ion include zirconium hydrofluoric acid, zirconium hydrofluoride (for example, sodium salt, potassium salt, lithium salt, ammonium salt) Salt, etc.). Of these, ammonium zirconium fluoride and zirconyl nitrate are particularly preferred.

On the other hand, the metal (a) -containing compound used as necessary in the metal compound component (A) is a metal (a) -containing ion such as a metal (a) ion or a fluoro metal (a) ion when energized during coating. A compound containing metal (a), specifically,
Examples of compounds that generate titanium ions include titanium chloride and titanium sulfate; examples of compounds that generate fluorotitanium ions include titanium hydrofluoric acid and titanium hydrofluoride (for example, sodium salts, potassium salts, lithium salts, and ammonium salts). Salt));
Examples of compounds that generate cobalt ions include cobalt chloride, cobalt bromide, cobalt iodide, cobalt nitrate, cobalt sulfate, cobalt acetate, and cobalt ammonium sulfate;
Examples of compounds that generate vanadium ions include lithium orthovanadate, sodium orthovanadate, lithium metavanadate, potassium metavanadate, sodium metavanadate, ammonium metavanadate, sodium pyrovanadate, vanadyl chloride, vanadyl sulfate;
Examples of compounds that generate tungsten ions include lithium tungstate, sodium tungstate, potassium tungstate, ammonium tungstate, sodium metatungstate, sodium paratungstate, ammonium pentatungstate, ammonium heptungstate, sodium phosphotungstate. , Barium borotungstate and the like;
Examples of compounds that generate molybdenum ions include lithium molybdate, sodium molybdate, potassium molybdate, ammonium heptamolybdate, calcium molybdate, magnesium molybdate, strontium molybdate, barium molybdate, phosphomolybdic acid, and phosphomolybdic acid. Sodium, zinc phosphomolybdate and the like;
Examples of compounds that generate copper ions include copper sulfate, copper (II) nitrate trihydrate, copper (II) ammonium sulfate hexahydrate, cupric oxide, and copper phosphate;
Examples of the compound that generates zinc ions include zinc acetate, zinc lactate, and zinc oxide.
Examples of the compound that generates indium ions include indium ammonium sulfate;
Examples of the compound that generates aluminum ions include aluminum phosphate, tricalcium aluminate, sodium aluminate and the like;
Examples of compounds that generate bismuth ions include inorganic bismuth-containing compounds such as bismuth chloride, bismuth oxychloride, bismuth bromide, bismuth silicate, bismuth hydroxide, bismuth trioxide, bismuth nitrate, bismuth nitrite, and bismuth oxycarbonate. Organic bismuth-containing compounds such as bismuth lactate, triphenyl bismuth, bismuth gallate, bismuth benzoate, bismuth citrate, bismuth methoxyacetate, bismuth acetate, bismuth formate, and bismuth 2,2-dimethylolpropionate;
Examples of the compound that generates yttrium ions include yttrium nitrate, yttrium acetate, yttrium chloride, yttrium sulfamate, yttrium lactate, and yttrium formate.

  In the lanthanoid metal compound, examples of the compound that generates lanthanum ions include lanthanum nitrate, lanthanum fluoride, lanthanum acetate, lanthanum boride, lanthanum phosphate, and lanthanum carbonate; Cerium (III), cerium chloride (III), cerium acetate (III), cerium oxalate (III), ammonium cerium nitrate (III), diammonium cerium nitrate (IV), etc .; Examples of compounds that produce praseodymium ions include nitric acid Praseodymium, praseodymium sulfate, praseodymium oxalate, etc .; Examples of compounds that generate neodymium ions include neodymium nitrate and neodymium oxide.

  Examples of the compound that generates an alkali metal ion include potassium sulfate, potassium nitrate, lithium sulfate, lithium nitrate, sodium sulfate, and sodium nitrate.

Examples of the compound that generates alkaline earth metal ions include calcium carbonate, magnesium nitrate, magnesium oxide, magnesium titanate, magnesium orthosilicate, and magnesium pyrophosphate.

  These metal (a) -containing compounds can be used alone or in combination of two or more.

  Among these metal (a) -containing compounds, the metal (a) contains a metal selected from titanium, cobalt, vanadium, tungsten, zinc, aluminum, lanthanum, praseodymium and magnesium, particularly titanium, cobalt, vanadium or tungsten. Compounds are preferred. Of these, ammonium titanium fluoride, cobalt nitrate, ammonium metavanadate, and ammonium tungstate are preferable.

Anionic group-containing resin component (B) :
As the resin component used in the film forming agent, an anionic resin is used in the present invention from the viewpoint of weather resistance and the like.

  Examples of the anionic resin include a resin having a group that can be anionized in an aqueous medium such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group. A resin having at least one carboxyl group therein, particularly at least one carboxyl group and hydroxyl group in one molecule is preferable. Examples of the resin type include polyester resin, epoxy resin, acrylic resin, polybutadiene resin, alkyd resin, polyurethane resin, and the like. Among these resins, from the viewpoints of weather resistance, corrosion resistance and the like, in particular, a carboxyl group-containing polyester resin (B-1), a carboxyl group-containing acrylic resin (B-2), and a carboxyl group-containing epoxy resin (B-3). Is preferred.

  The carboxyl group-containing polyester resin (B-1) can be generally obtained by subjecting a polybasic acid and a polyhydric alcohol to an esterification reaction according to a conventional method, for example, a direct esterification method or a transesterification method.

  Examples of the polybasic acid include phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, tetrahydrophthalic anhydride, hexahydro Dibasic acids such as phthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride or their anhydrides; lower alkyl esters of these dibasic acids; trimellitic acid, hexahydrotrimellitic acid, trihydric anhydride Examples thereof include tribasic or higher polybasic acids such as meritic acid, methylcyclohexenic carboxylic acid, pyromellitic anhydride, and anhydrides thereof. Among these, one or two alicyclic structures and at least 2 percyclic molecule are included in one molecule. Alicyclic polybasic acid having one carboxyl group, for example, hexa Rofutaru acid, hexahydroisophthalic acid, hexahydroterephthalic acid, hexahydroterephthalic trimellitic acid, tetrahydrophthalic acid, methyl hexahydrophthalic acid and their anhydrides, in particular, hexahydroterephthalic acid are preferred. Moreover, the said polybasic acid can be used together with monobasic acids, such as a benzoic acid, a crotonic acid, pt-butylbenzoic acid, for the purpose of molecular weight adjustment etc. as needed. Further, oil fatty acids such as coconut oil fatty acid and dehydrated castor oil fatty acid can be used in combination.

As the polyhydric alcohol, a dihydric alcohol having two hydroxyl groups in one molecule and a polyhydric alcohol having three or more hydroxyl groups in one molecule can be used. Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2 , 3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentane Diol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-4 Glycols such as 5-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, and neopentyl glycol ester of hydroxypivalic acid; Polylactone diols obtained by adding lactones such as ε-caprolactone to glycols of the above; polyester diols such as bis (hydroxyethyl) terephthalate; 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, spiroglycol, dihydroxymethyltricyclo Examples thereof include alicyclic dihydric alcohols such as decane. Examples of the polyhydric alcohol having 3 or more hydroxyl groups in one molecule include glycerin, trimethylolpropane, trimethylolethane, and diglyceride. , Triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, mannitol and the like.

  Among these, one or two alicyclic structures having about 4 to 6-membered rings in one molecule and an alicyclic polyhydric alcohol having at least two hydroxyl groups such as cyclohexane-1,4-dimethylol, water Bisphenol A, spiroglycol, dihydroxymethyltricyclodecane, etc .; glycols having 4 to 9 carbon atoms such as diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4- Pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene Coal, tetramethylene glycol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4- Hexanediol, 2,5-hexanediol, neopentyl glycol and the like are preferable.

  The reaction ratio of the acid group-containing compound such as polybasic acid and the hydroxyl group-containing compound such as polyhydric alcohol is not particularly limited, but the acid group of the acid group-containing compound is 1 mol of the hydroxyl group of the hydroxyl group-containing compound. Is usually 0.4 to 0.95 mol, preferably 0.45 to 0.85 mol, and more preferably 0.5 to 0.8 mol.

  The introduction of the carboxyl group into the polyester resin thus obtained is, for example, a half esterification reaction with a part of the hydroxyl group of the polyester resin at the temperature of 100 to 180 ° C. of the polybasic acid anhydride. By doing so, a carboxyl group-containing polyester resin can be obtained. At this time, from the viewpoint of production stability and the like, a small amount of a high-boiling polar solvent can be added to the reaction system to lower the viscosity of the system. Examples of the high boiling polar solvent include cyclohexanone.

  The carboxyl group-containing polyester resin (B-1) generally has a number average molecular weight (Note 1) in the range of 500 to 50,000, preferably 800 to 10,000, more preferably 1,000 to 3,000. Acid values within the range of 5-150 mgKOH / g, preferably 8-120 mgKOH / g, more preferably 8-100 mgKOH / g, generally 20-800 mgKOH / g, preferably 40-500 mgKOH / g, more preferably 60-200 mgKOH Can have a hydroxyl value in the range of / g.

(Note 1) Number average molecular weight: In accordance with the method described in JISK 0124-83, TSK GEL4000HXL, TSKG3000HXL, TSK G2 are used as separation columns.
Chromatography obtained with an RI refractometer using 4 pieces of 500HXL and TSKG2000HXL (trade name, manufactured by Tosoh Corporation) and using GPC tetrahydrofuran as an eluent at a temperature of 40 ° C. and a flow rate of 1.0 ml / min. It was obtained from a calibration curve of grams and standard polystyrene.

  The carboxyl group-containing acrylic resin (B-2) is, for example, a carboxyl group-containing radical polymerizable unsaturated monomer, a hydroxyl group-containing radical polymerizable unsaturated monomer, if necessary, and other radical polymerizable unsaturated monomers. It can be produced by copolymerizing a monomer.

  Examples of the carboxyl group-containing radical polymerizable unsaturated monomer include monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and the like. Examples of the unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and other than these, FM1, Plaxel FM2, Plaxel FM3 (above, Daicel Chemical Industries, trade name, caprolactone-modified methacrylic acid hydroxy ester), Plaxel FA1, Plaxel FA2, Plaxel FA3 (above, Daicel Chemical Industries, trade name, caprolactone-modified acrylic acid) Hydro Shiesuteru acids) and the like.

Examples of the other radical polymerizable unsaturated monomer include γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, and γ- (meth) acryloyloxypropyltriethoxy. Alkoxysilyl group-containing unsaturated monomers such as silane and vinyltrimethoxysilane; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic C ₁ -C ₁₈ alkyl or cycloalkyl esters of (meth) acrylic acid such as hexyl acid, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate; styrene, α-methylstyrene, Aromatic vinyl modules such as vinyl toluene Mer acids; (meth) acrylic acid amide, N- butoxymethyl (meth) acrylamide, N- methylol - Le (meth) acrylamide (meth) acrylamide and derivatives thereof; (meth) acrylonitrile compounds, and the like.

  The carboxyl group-containing acrylic resin (B-2) is usually prepared from the above-mentioned carboxyl group-containing radical polymerizable unsaturated monomer, if necessary, a hydroxyl group-containing radical polymerizable unsaturated monomer, and other radical polymerizable unsaturated monomers. A saturated monomer can be obtained by radical polymerization reaction in a solvent in the presence of a polymerization initiator. In this polymerization reaction, the carboxyl group-containing polymerizable unsaturated monomer is 1 to 20% by mass, particularly 4 to 10% by mass, and the hydroxyl group-containing radical polymerizable unsaturated monomer is 0 to 40% by mass, particularly 5 to 30%. The mass% and other radical polymerizable unsaturated monomers are preferably used in the range of 40 to 99 mass%, particularly 60 to 91 mass%.

  Examples of the solvent used for the polymerization reaction include alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, and isobutyl alcohol; diethylene glycol monobutyl ether, methyl carbitol, 2-methoxyethanol, 2-ethoxy Ethanol, 2-isopropoxyethanol, 2-butoxyethanol, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol monomethyl And ethers such as ether.

  Other than this, for example, aromatic hydrocarbons such as xylene and toluene; ketones such as acetone, methyl ethyl ketone, 2-pentanone, 2-hexanone, methyl isobutyl ketone, isophorone, and cyclohexanone; methyl acetate, Esters such as ethyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl propionate, and ethyl propionate can be used in combination.

  As the radical polymerization initiator used for radical copolymerization, for example, benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumyl peroxide, cumene hydroperoxide, diisopropyl benzanthane hydroperoxide, Peroxides such as t-butylperoxybenzoate, lauryl peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate; α, α′-azobisisobutyronitrile, azobisdimethylvaleronitrile And azo compounds such as azobiscyclohexanecarbonitrile.

  The carboxyl group-containing acrylic resin (B-2) produced as described above is generally 5,000 to 150,000, preferably 10,000 to 125,000, more preferably 20,000 to 100,000. In the range of weight average molecular weight (Note 2), and generally in the range of 10-140 mg KOH / g, especially 20-130 mg KOH / g, more particularly 30-120 mg KOH / g and generally 20-170 mg KOH / g In particular, it may have a hydroxyl value in the range of 25 to 165 mg KOH / g, more particularly 30 to 160 mg KOH / g.

(Note 2) Weight average molecular weight: According to the method described in JISK 0124-83, TSK GEL4000HXL, TSKG3000HXL, TSKG as separation columns
Chromatogram obtained by RI refractometer using 4 pieces of 2500HXL and TSKG2000HXL (trade name, manufactured by Tosoh Corporation) and tetrahydrofuran for GPC as eluent at a temperature of 40 ° C. and a flow rate of 1.0 ml / min. And a standard polystyrene calibration curve.

  The carboxyl group-containing epoxy resin (B-3) is, for example, a half of a polybasic acid anhydride at a temperature of about 100 to about 180 ° C. in part of the hydroxyl group of the epoxy resin (B-3-1). It can obtain by adding by making it esterify.

  As said epoxy resin (B-3-1), the epoxy group of the epoxy resin which has at least 1 epoxy group in 1 molecule obtained by reaction of a polyphenol compound and epichlorohydrin is made into the active hydrogen containing compound (B-3- An epoxy resin blocked by 2) can be used.

  As the polyphenol compound that can be used for the production of the epoxy resin (B-3-1), those known per se can be used, and examples of such a polyphenol compound include bis (4-hydroxyphenyl) -2. , 2-propane (bisphenol A), 4,4-dihydroxybenzophenone, bis (4-hydroxyphenyl) methane (bisphenol F), bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetra (4-hydroxyphenyl) -1,1,2,2 -Ethane, 4,4-dihydroxydiphenylsulfone (bisphenol S), phenol novolac Such as cresol novolac can be mentioned.

で示されるものが好適である。 Moreover, as an epoxy resin obtained by reaction of a polyphenol compound and epichlorohydrin, from the viewpoint of long-term corrosion resistance, for example, exposure resistance, among them, the following formula derived from a bisphenol-type epoxy resin, particularly bisphenol A:

Those represented by are preferred.

  Examples of such commercially available epoxy resin (B-3-1) include those sold by Japan Epoxy Resins Co., Ltd. under trade names such as jER828EL, jER1002, jER1004, jER1007, and the like.

  The epoxy resin (B-3-1) generally has a number average molecular weight (Note 1) in the range of 400 to 100,000, preferably 600 to 60,000, more preferably 800 to 20,000, generally 180 to It can have an epoxy equivalent weight in the range of 70,000, preferably 240-40,000, more preferably 300-15,000.

  As the active hydrogen-containing compound (B-3-2) to be reacted with the epoxy group of the epoxy resin (B-3-1), a phenol group or carboxyl group-containing compound having at least one active hydrogen-containing group in one molecule A compound selected from the group consisting of monophenols, aliphatic monocarboxylic acids, and aromatic monocarboxylic acids is preferable from the viewpoint of ease of reaction, storage stability of the resin emulsion, and the like.

  Specific examples of the monophenols include phenol, cresol, ethylphenol, para-tert-butylphenol, and nonylphenol.

  Examples of the aliphatic carboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, lactic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Examples of the aromatic carboxylic acids include benzoic acid, Examples thereof include gallic acid.

  The reaction ratio of the active hydrogen group of the active hydrogen-containing compound (B-3-2) to the epoxy group of the epoxy resin (B-3-1) is usually 1.5 to 0.75 mol with respect to 1 mol of the epoxy group. , Preferably it can be in the range of 1.2-0.8 mol. In addition, since the epoxy group of an epoxy resin (B-3-1) is blocked with the active hydrogen containing compound (B-3-2), it is excellent in storage stability.

  In the carboxyl group-containing epoxy resin (B-3), the epoxy group of the epoxy resin (B-3-1) is blocked with the active hydrogen-containing compound (B-3-2), and the acid anhydride compound (B-3- It can be produced by reacting 3) to introduce a carboxyl group.

  Examples of the acid anhydride compound (B-3-3) include dibasic acid anhydrides such as succinic acid, maleic acid, phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, and methylhexahydrophthalic acid. Also, tribasic acid monoanhydrides such as trimellitic anhydride can be used.

  The carboxyl group-containing epoxy resin (B-3) thus obtained is generally an acid within the range of 0.1 to 150 mgKOH / g, preferably 0.5 to 120 mgKOH / g, more preferably 1 to 100 mgKOH / g. Can have a valence.

Furthermore, the anionic group-containing resin component (B) can contain a blocked polyisocyanate compound and / or a melamine resin as a crosslinking agent, if necessary.

  Examples of the blocked polyisocyanate compound include those obtained by blocking an aromatic, alicyclic or aliphatic polyisocyanate compound with a blocking agent, and these can be used alone or in combination of two or more.

  Specific examples of the aromatic polyisocyanate include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4'- or 4,4. '-Diphenylmethane diisocyanate (MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanato Examples include diphenylmethane, crude MDI, 1,5-naphthylene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate.

  Examples of the aliphatic polyisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. 2,6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, etc. Can be mentioned.

  Examples of the alicyclic polyisocyanate include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), p-xylylene diisocyanate (XDI), α, α, α ′, α′-. Examples thereof include tetramethylxylylene diisocyanate (TMXDI) and cyclohexylene diisocyanate.

  Among these polyisocyanate compounds, aliphatic polyisocyanates and alicyclic polyisocyanates are preferable from the viewpoint of weather resistance and the like.

  The blocking agent is to block by adding to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound produced by the addition of the blocking agent is stable at ordinary temperature and at a general electrodeposition coating baking temperature. It is desirable that the isocyanate group can be regenerated by dissociating the blocking agent when heated to a temperature of about 100 ° C. to about 200 ° C.

  Examples of the blocking agent satisfying such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol. Aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; propylene glycol; Dipropylene glycol, 1,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol 1,4-pentanediol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,5-hexane Examples thereof include hydroxyl group-containing compounds such as diol, 1,4-hexanediol, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, dimethylolvaleric acid and glyceric acid.

  As the blocked polyisocyanate compound, isophorone diisocyanate blocked with methyl ethyl ketoxime is particularly preferable.

  The melamine resin includes a methylolated melamine resin obtained by methylolating melamine with formaldehyde; an alkylated melamine resin obtained by etherifying the methylol group with monoalcohol; a methylolated melamine resin having an imino group, an alkylated melamine resin, and the like. Can be mentioned. Further, in the etherification of the methylol group, those obtained by mixed alkylation using two or more kinds of monoalcohols can also be used. Examples of the monoalcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, t-butyl alcohol, 2-ethylbutanol, and 2-ethylhexanol. It is done.

  Specific examples of the melamine resin include methylated melamine resins, imino group-containing methylated melamine resins, methylated / butylated melamine resins, imino group-containing methylated / butylated melamine resins, and the like. A melamine resin and a methylated / butylated melamine resin are preferred.

  Examples of commercially available melamine resins include “Cymel 202”, “Cymel 232”, “Cymel 235”, “Cymel 236”, “Cymel 238”, “Cymel 254”, “Cymel 266”, “Cymel 267”, “Cymel 272”, “Cymel 285”, “Cymel 301”, “Cymel 303”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 370”, “Cymel 701”, “Cymel 703”, “Cymel 736”, “Cymel 738”, “Cymel 771”, “Cymel 1141”, “Cymel 1156”, “Cymel 1158”, etc. (above, trade name, manufactured by Nippon Cytec Co., Ltd.), “Uban 120”, “Uban 20HS ”,“ Uban 2021 ”,“ Uban 2028 ”,“ Uban 206 "Such as (or more, manufactured by Mitsui Chemicals, Inc., trade name)," Melan 522 "(manufactured by Hitachi Chemical Co., Ltd., trade name) and the like.

  The mixing ratio of the anionic resin (base resin) and the crosslinking agent in the anionic group-containing resin component (B) is usually 50 to 90 mass for the anionic resin based on the total solid mass of the anionic resin and the crosslinking agent. %, Preferably 55 to 85% by mass, more preferably 60 to 80% by mass, and the crosslinking agent is usually 10 to 50% by mass, preferably 15 to 45% by mass, more preferably 20 to 40% by mass. be able to.

  The anionic group-containing resin component (B) described above can be made into a resin emulsion by adding a neutralizing agent such as a basic compound and deionized water and dispersing in water, and is used for production of a film forming agent. be able to.

  Examples of the basic compound include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide; ammonia; ethylamine, propylamine, butylamine , Primary amines such as benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol; diethylamine, diethanolamine, di-n- or di-iso-propanolamine, N-methylethanolamine Secondary monoamines such as N-ethylethanolamine; tertiary monoamines such as dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanolamine, dimethylaminoethanol, etc. ; Diethylenetriamine, hydroxyethylaminoethylamine, ethylamino ethylamine, may be mentioned polyamines such as methylamino propylamine.

  It is preferable to use a basic compound within the range of 0.1-1 equivalent normally with respect to the carboxyl group of an anionic group containing resin component (B), especially 0.3-0.9 equivalent.

  The film-forming agent is selected from a zirconium compound and, if necessary, at least selected from titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, aluminum, bismuth, yttrium, lanthanoid metal, alkali metal and alkaline earth metal The metal compound component (A) composed of a compound containing one kind of metal (a) is 30 to 20,000 ppm, preferably 50 to 10,000 ppm, more preferably 100 to 5 in terms of total metal amount (in terms of mass). And anionic group-containing resin component (B) can be contained in an amount of 1 to 40% by mass, preferably 5 to 35% by mass, more preferably 10 to 30% by mass, thereby preventing corrosion. An excellent film structure can be formed.

  When the metal compound component (A) contains a metal (a) -containing compound, the content can be changed depending on the use of the coated article formed by the method of the present invention, but the metal compound component (A) In general, it is 90% by mass or less, preferably 5 to 80% by mass, and more preferably 10 to 75% by mass.

  The film-forming agent further contains other additives such as pigments, catalysts, organic solvents, pigment dispersants, surface conditioners, surfactants, etc., if necessary, in a blending amount usually used in the paint field. can do. Examples of the pigments and catalysts include coloring pigments such as titanium white and carbon black; extender pigments such as clay, talc and barita; rust preventive pigments such as aluminum dihydrogen phosphate and aluminum phosphomolybdate; dibutyl tin Organic tin compounds such as oxide and dioctyltin oxide; tin compounds such as dialkyltin aliphatic or aromatic carboxylates such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dioctyltin dibenzoate, and dibutyltin dibenzoate Is mentioned.

The film-forming agent can be prepared, for example, by the methods (1) to (3) described below:
(1) The anionic group-containing resin component (B) and optionally other additives are combined together and mixed thoroughly to form a dissolved varnish, which is then mixed with an aqueous medium such as sodium hydroxide, potassium hydroxide, Alkali metal or alkaline earth metal hydroxides such as lithium hydroxide, calcium hydroxide and barium hydroxide; ammonia; ethylamine, propylamine, butylamine, benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol , Primary monoamines such as 3-aminopropanol; secondary monoamines such as diethylamine, diethanolamine, di-n- or di-iso-propanolamine, N-methylethanolamine, N-ethylethanolamine; dimethylethanolamine, Trimethylamine, Tertiary monoamines such as reethylamine, triisopropylamine, methyldiethanolamine, dimethylaminoethanol; polyamines such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, and mixtures of two or more thereof A method of blending the metal compound component (A) in an emulsion obtained by adding a selected neutralizing agent and dispersing in water.
(2) A pigment, paste, catalyst, other additives, and water are added to the metal compound component (A) and dispersed in advance to prepare a pigment dispersion paste. The pigment dispersion paste is then used as an anionic group-containing resin component (B) emulsion. How to add to.
(3) A method in which the metal compound component (A) is diluted with water and mixed in a bath of an electrodeposition paint prepared in advance.

The film forming agent is diluted with deionized water or the like, and the bath solid concentration is usually 5 to 40% by mass, preferably 8 to 20% by mass, and the pH is usually 4 to 9, preferably 5 to 8. Can be adjusted and used.

  The film forming agent prepared as described above can form the target film structure of the present invention on a metal substrate by at least two-stage multi-stage energization method described below.

Multi-stage energization painting :
The coating of the film-forming agent according to the present invention can be performed by a multi-stage energization method. Specifically, the above-described film-forming agent is used as a bath, and the first-stage coating is performed using the metal substrate as a cathode. By being energized with a voltage (V ₁ ) of generally _{1 to} 100 V, preferably _{1 to} 50 V, more preferably 5 to 40 V, usually 10 to 360 seconds, preferably 30 to 180 seconds, while immersed in a film forming agent. Next, the second and subsequent coatings are generally 50 to 400 V, preferably 75 to 370 V, more preferably 100 to 350 V, with the metal substrate as the anode in a state where the metal substrate is immersed in the film forming agent. voltage _{(V 2),} usually 60 to 600 seconds, preferably 75 to 400 seconds, more preferably can be carried out by passing 90-240 seconds.

  Thus, the coating (X) can be formed by selectively depositing the metal compound component (A) on the metal substrate by the first-stage coating using the metal substrate as the cathode. The coating (Y) can be formed by selectively precipitating the anionic group-containing resin component (B) on the coating (X) having electrical resistance by coating in the second and subsequent stages using as the anode.

  According to the present invention, the composition on the first layer (X) is greatly different by reversing from the state in which the metal substrate is used as the cathode in the state of being immersed in the film forming agent to the state in which the object is the anode. The second-layer coating (Y) can be formed continuously, whereby a multilayer coating structure with better anticorrosion properties can be formed.

In particular, in order to sufficiently form the film (Y) on the film (X), the first coating is generally 0.1 to 1.5 mA / cm ² , preferably 0.15 to 1.2 mA / cm. ² , more preferably 0.2 to 1.0 mA / cm ² .

  As the deposition mechanism of the multilayer coating, first, the zirconium ion species (for example, zirconium and fluorine) in the film forming agent are caused by the pH increase in the vicinity of the metal substrate under the first-stage energization condition using the metal substrate as the cathode. Complex ions) undergo a hydrolysis reaction and deposit on the metal substrate as a hardly soluble coating (X) (mainly zirconium oxide). Next, since the metal substrate is switched to the anode by the second-stage energization, the pH in the vicinity of the metal substrate is lowered during the second-stage energization, and thereby hardly soluble zirconium oxide is deposited on the metal substrate. First, a film (Y) containing an anionic group-containing resin component (B) or a pigment as a main component is formed, and the film structure of the present invention can be obtained.

  Depending on the energization conditions, a film mainly composed of an anionic group-containing resin component (B) or a pigment may be deposited on the anode that is the counter electrode in the first stage energization during the first stage energization. Therefore, in order to facilitate continuous coating in the second and subsequent energization using a metal substrate as an anode, an electrode covered with a diaphragm (diaphragm electrode) is used as an electrode, and the surface of the electrode is anionic. It is desirable to prevent the group-containing resin component (B) from adhering.

  The bath temperature of the film-forming agent is usually 5 to 45 ° C., preferably 10 to 40 ° C., more preferably 20 to 35 ° C.

The deposited film can be baked and cured. The baking temperature of the film is suitably about 100 to about 200 ° C., preferably about 120 to about 180 ° C. on the surface of the coating, and the baking time is 5 to 90 minutes, preferably 10 to 50 minutes. Can be about.

  By coating the film forming agent according to the present invention by the above-described multistage energization method, the zirconium compound and the metal (a) -containing compound are combined on the metal base material based on the total mass solid content of the film, and the total metal amount (mass The film (X) having a thickness of 25 to 100% by mass, particularly 30 to 99% by mass, more particularly 35 to 95% by mass, with a thickness of 0.01 to 5 μm, particularly 0.03 to 5 μm, and the film On the basis of the total mass solid content of the film on (X), the zirconium compound and the metal (a) -containing compound are less than 25% by mass, particularly 0.5 to 20% by mass, in terms of the total metal amount (in terms of mass). In particular, it contains 1 to 10% by weight and contains an anionic group-containing resin component in an amount of 50 to 95% by weight, particularly 60 to 92.5% by weight, more particularly 70 to 90% by weight. 0.5-25 μm film (Y It can be allowed to form comprising at film structure.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited only to these Examples. “Parts” and “%” are “parts by mass” and “% by mass”.

Production Example 1: Production of carboxyl group-containing polyester resin In a reactor having a heating device, a stirrer, a nitrogen introduction tube and a separator, 550 parts of hexahydrophthalic anhydride, 160 parts of adipic acid, 220 parts of trimethylolpropane, neopentyl glycol 170 parts and 350 parts of 2-butyl-2-ethyl-1,3-propanediol were charged, heating was started under dry nitrogen, and the temperature was gradually raised to 230 ° C. to conduct an esterification reaction.

  Further, the temperature was maintained at 230 ° C., esterification was carried out to an acid value of 1 mg KOH / g or less, then cooled to 170 ° C., 160 parts of trimellitic anhydride was added, 380 parts of ethylene glycol monobutyl ether was further added, and the solid content was 80 % Carboxy group-containing polyester resin solution. The carboxy group-containing polyester resin had an acid value of 60 mgKOH / g, a hydroxyl value of 90 mgKOH / g, and a number average molecular weight of 1,500.

Production Example 2: Production of carboxyl group-containing acrylic resin Into a flask equipped with a stirrer, thermometer, nitrogen introduction tube and reflux condenser, 290 parts of propylene glycol monomethyl ether was charged and maintained at 120 ° C. The mixture was added dropwise over 3 hours, then 3 parts of azobisdimethylvaleronitrile was added, and the reaction was carried out while maintaining at 120 ° C. for 1 hour to obtain a carboxyl group-containing acrylic resin solution having a resin solid content of 65%. . The carboxyl group-containing acrylic resin had an acid value of 78 mgKOH / g, a hydroxyl value of 145 mgKOH / g, and a weight average molecular weight of 16,000.

"blend"
Styrene 60 parts n-butyl acrylate 300 parts 2-hydroxyethyl acrylate 180 parts Acrylic acid 60 parts Azobisdiisobutyronitrile 36 parts

Production Example 3: Production of carboxyl group-containing epoxy resin To a flask equipped with a stirrer, thermometer, nitrogen introduction tube and reflux condenser, jER828EL (manufactured by Japan Epoxy Resin Co., Ltd., trade name, epoxy resin epoxy equivalent 190 molecular weight 350) To 500 parts, 200 parts of bisphenol A and 0.1 part of dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent reached 750. Thereto, 135 parts of dimethylol butyric acid was added and reacted at 130 ° C. for 4 hours. Subsequently, after adding 77 parts of trimellitic anhydride, 228 parts of ethylene glycol monobutyl ether was added to obtain a carboxy group-containing epoxy resin solution having a solid content of 80%. The carboxy group-containing epoxy resin had an acid value of 78 mgKOH / g, a hydroxyl value of 140 mgKOH / g, and a number average molecular weight of about 1800.

Production Example 4: Curing agent No. Production of 1 44 parts of methyl isobutyl ketone was added to 222 parts of isophorone diisocyanate, and the temperature was raised to 70 ° C. Thereafter, 174 parts of methyl ethyl ketoxime was added dropwise over 2 hours, and sampling was performed over time while maintaining this temperature, and it was confirmed by infrared absorption spectrum measurement that there was no absorption of unreacted isocyanate. Curing agent No. of block polyisocyanate compound 1 was obtained.

Production Example 5: Emulsion No. Production of Curing Agent No. 1 to 87.5 parts (solid content 70 parts) of a carboxyl group-containing polyester resin 80% solid content obtained in Production Example 1 above. 1 33.3 parts (solid content 30 parts), triethylamine 3 parts (0.4 equivalent neutralized content) and deionized water 188.7 parts were added to disperse in water, and emulsion No. 1 having a solid content of 32% was added. 1 was obtained.

Production Examples 6 to 8: Emulsion No. 2-No. Production of Emulsion No. 4 with the same composition as shown in Table 1 below. 2-No. 4 was obtained.

(Note 3) Nicalak MX-430: Sanwa Chemical Co., Ltd., trade name, melamine resin, solid content 100%.

Production Example 9: Acrylic Resin Solution for Dispersing Pigment In an ordinary acrylic resin reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 37 parts of ethylene glycol monobutyl ether was charged and stirred at a temperature of 110 ° C.

  The following “mixture” was dropped therein over 3 hours. After completion of the dropwise addition, the mixture was aged at 110 ° C. for 30 minutes, and then an additional catalyst mixture composed of 20 parts of ethylene glycol monobutyl ether and 0.5 part of azobisisobutyronitrile was added dropwise over 1 hour. Next, the mixture was aged at 110 ° C. for 1 hour and then cooled to obtain an acrylic resin solution for pigment dispersion having a solid content of 55%.

"blend"
10 parts of styrene
Methyl methacrylate 35 parts
20 parts of 2-ethylhexyl methacrylate
2-hydroxyethyl methacrylate 10 parts
NF biisomer S20W (Note 4) 40 parts
Azobisisobutyronitrile 1 part
5 parts isobutyl alcohol

(Note 4) NF biisomer S20W: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name, 50% water-diluted product of methoxypolyethylene glycol monomethacrylate, molecular weight about 2,080
.

Production Example 10: Pigment dispersion paste No. Production of 1 Acrylic resin solution for pigment dispersion having a solid content of 55% obtained in Production Example 9 (5 parts solids), 14 parts JR-600E (Note 5), Carbon MA-7 (Note 6) 0.3 parts, 9.7 parts of hydrite PXN (Note 7), 1 part of dioctyltin oxide and 23.2 parts of deionized water were dispersed for 20 hours in a ball mill, and pigment dispersion paste No. 5 having a solid content of 55% was dispersed. 1 was obtained.

Production Example 11: Pigment dispersion paste No. Production Example 2 The same procedure as in Production Example 10 was carried out except that the components shown in Table 2 below were used. 2 was obtained.

(Note 5) JR-600E: Product name, titanium white, manufactured by Teika.
(Note 6) Carbon MA-7: trade name, carbon black, manufactured by Mitsubishi Kasei.
(Note 7) Hydrite PXN: Product name, Kaolin, manufactured by Georgia Kaolin.

Production Example 12
Emulsion No. 1 219 parts (solid content 70 parts), 55% pigment dispersion paste No. obtained in Production Example 10 No. 1 54.5 parts (solid content 30 parts) and deionized water 726.5 parts were mixed to form a 10% solids bath, and then 1.3 parts of zirconium hydrogen fluoride ammonium was added to form the film forming agent No. 1 1 was obtained.

Production Examples 13 to 26
Except for the formulations shown in Tables 3 and 4 below, film-forming agent No. 2-No. 15 was obtained.

Example 1
Film forming agent No. 1 bath was adjusted to 28 ° C., and a cold-rolled steel sheet (70 mm × 150 mm × 0.8 mm) as an object to be coated was immersed as a cathode (distance between electrodes 15 cm), and the first-stage coating was performed at 5V at 60V. It was performed by energizing for 2 seconds.

Subsequently, the second-stage coating was performed by applying current at 260 V for 120 seconds using a cold-rolled steel plate (70 mm × 150 mm × 0.8 mm) as an anode (distance between electrodes 15 cm). The obtained film was baked with an electric dryer at 170 ° C. for 20 minutes. 1 was obtained.
The current density during the first stage energization was 0.2 mA / cm ² .

Examples 2-14
Except for using the film forming agent and the coating conditions shown in Table 5 and Table 6, the film No. 2-No. 14 was obtained.

Comparative Examples 1-14
In the same manner as in Example 1 except that the film forming agent and the coating conditions shown in Tables 7 and 8 were used, the test plate No. 15-No. 28 was obtained.

(Note 8) Current density:
A cold-rolled steel sheet (70 mm × 150 mm × 0.8 mm) as the object to be coated was immersed in a film forming agent as a cathode (distance between electrodes 15 cm), and the current density at the time of voltage application in the first stage was determined.

(Note 9) Film state:
The test plate was cut and the film states of the film (X) and film (Y) were observed using HF-2000 (manufactured by Hitachi, Ltd., field emission type transmission electron microscope). The film state was evaluated according to the following criteria.
○ indicates that layer separation is clearly observed.
Δ indicates that the boundary between the film (X) and the film (Y) is not clear, but some layer separation is observed.
X indicates no layer separation.

(Note 10) Zr and metal amount of metal (a) (%):
The amount of metal (mass%) in the film (X) was measured using IX-3100RF (Rigaku Corporation, trade name, X-ray fluorescence analyzer).

(Note 11) Content of resin component (B):
The film (Y) before baking was scraped off and determined according to the following formula (2).
Mass after drying coating (Y) at 105 ° C. for 3 hours: b1
Residual mass after baking in 800 ° C crucible for 5 hours ... b2
Resin component (B) content (%)
= [(B1-b2) / b1] × 100 Formula (2)

(Note 12) Anticorrosion:
A cross-cut wound was made in the electrodeposition coating film with a knife so as to reach the base of the test plate, and a salt spray resistance test was conducted for 480 hours according to JISZ-2371. The evaluation was made according to the following criteria based on the rust and blister width from the knife scratch.
A: The maximum width of rust and blisters is less than 2 mm (one side) from the cut part.
○: The maximum width of rust and blisters is 2 mm or more and less than 3 mm (one side) from the cut part.
Δ indicates that the maximum width of rust and blisters is 3 mm or more and less than 4 mm (one side) from the cut part.
X indicates that the maximum width of rust and swelling is 4 mm or more (one side) from the cut portion.

(Note 13) Exposure resistance:
After spraying the test plate with WP-300 (trade name, waterborne intermediate coating) manufactured by Kansai Paint Co., Ltd. so that the cured film thickness is 25 μm, it is 140 ° C. × 30 with an electric hot air dryer. Partial baking was performed. Furthermore, after spraying neoamylac 6000 (manufactured by Kansai Paint Co., Ltd., trade name, top coat) on the intermediate coating film so as to have a cured film thickness of 35 μm, it is 140 ° C. in an electric hot air dryer. Baking was performed for 30 minutes to prepare a blue test plate.
The resulting paint film on the test plate is cross-cut with a knife so that it reaches the substrate, and this is exposed horizontally in Chikura Town, Chiba Prefecture for one year. Evaluation was made according to the following criteria according to the width.
A: The maximum width of rust or swelling is less than 2 mm from the cut part (one side).
○: The maximum width of rust or blister is 2mm or more and less than 3mm (one side) from the cut part
.
△ indicates that the maximum width of rust or blister is 3 mm or more from the cut part and less than 4 mm (one side)
.
X indicates that the maximum width of rust or swelling is 4 mm or more (one side) from the cut portion.

(Note 14) Finish:
The surface roughness value (Ra) of the coated surface of the test plate was measured at a cutoff of 0.8 mm using a surf test 301 (manufactured by Mitutoyo Corporation, trade name, surface roughness meter).
○ has a surface roughness value (Ra) of less than 0.2 μm.
Δ has a surface roughness value (Ra) of 0.2 μm or more and less than 0.3 μm.
X has a surface roughness value (Ra) of 0.3 μm or more.

(Note 15) Weather resistance:
Each test plate having a dry film thickness of 20 μm is subjected to an accelerated weather resistance test as defined in JIS K-5600-7-7, and the 60-degree specular reflectance of the coated surface according to JIS K-5600-4-7 (1999). The time for (%) to divide 80% was measured.
◎ indicates that the time when the 60-degree specular reflectance (%) divides 80% is 200 hours or more.
○ indicates that the time when the 60-degree specular reflectance (%) divides 80% is 150 hours or more and less than 200 hours.
Δ indicates that the time when the 60-degree specular reflectance (%) divides 80% is 50 hours or more and less than 150 hours.
X indicates that the time when the 60-degree specular reflectance (%) divides 80% is less than 50 hours.

(Note 16) Film former stability:
Each film-forming agent was stirred at 30 ° C. with the container sealed for 30 days. Thereafter, the entire amount of the film-forming agent was filtered using a 400 mesh filter screen, and the remaining amount (mg / L) was measured.
A is less than 5 mg / L.
○ is 5 mg / L or more and less than 10 mg / L.
Δ is 10 mg / L or more and less than 15 mg / L.
X is 15 mg / L or more.

Claims (10)

A method of forming a film by coating a metal base material with a film forming agent in a multi-stage energization method of at least two stages,
(I) The film forming agent is composed of a zirconium compound and, if necessary, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, aluminum, bismuth, yttrium, lanthanoid metal, alkali metal, and alkaline earth metal. A compound containing at least one selected metal (a) in a total metal amount (in terms of mass) of 30 to 20,000 ppm, and an anionic group-containing resin component 1 to 40% by mass,
(Ii) First stage coating was performed by energizing for 10 to 360 seconds at a voltage of 1 to 50 V with the metal substrate as a cathode in a state where the metal substrate was immersed in the film forming agent, and (iii) metal A surface-treated film characterized by performing the second and subsequent coatings by applying current for 60 to 600 seconds at a voltage of 50 to 400 V using a metal substrate as an anode while the substrate is immersed in a film forming agent. Forming method. The method according to claim 1, wherein the first-stage coating is further performed at a current density of 0.05 to 1.5 mA / cm ² .   The method according to claim 1 or 2, wherein the film forming agent contains a zirconium compound and a metal (a) -containing compound in a total metal amount (in terms of mass) of 50 to 10,000 ppm.   The method according to any one of claims 1 to 3, wherein the film forming agent contains 5 to 35 mass% of a resin component.   The first stage of coating is performed by applying a voltage of 2 to 40 V for 30 to 300 seconds using the metal base as a cathode, and then the second and subsequent stages of coating are performed at a voltage of 75 to 370 V using the metal base as an anode. The method according to any one of claims 1 to 4, which is carried out by energizing for -400 seconds. The method according to claim 1, wherein the anionic group-containing resin component comprises an anionic resin and a crosslinking agent.   The method according to claim 6, wherein the anionic resin is selected from a carboxyl group-containing polyester resin, a carboxyl group-containing acrylic resin, and a carboxyl group-containing epoxy resin.   The method according to claim 6, wherein the crosslinking agent is selected from a blocked polyisocyanate compound and a melamine resin.   The zirconium compound and the metal (a) -containing compound are 25 to 100 masses in terms of the total metal amount (in terms of mass) based on the total mass solid content of the coating formed by the method according to claim 1. % Of the coating (X) having a thickness of 0.01 to 5 μm and the total amount of the zirconium compound and the metal (a) -containing compound on the basis of the total solid mass of the coating on the coating (X). A film structure comprising a film (Y) having a thickness of 0.1 to 30 μm, containing less than 25% by mass (in terms of mass) and containing 50 to 95% by mass of an anionic group-containing resin component.   A coated article having a surface-treated film formed by the method according to claim 1.