JP5547375B2 - Rust preventive paint composition - Google Patents

Description

  The present invention relates to a coating composition having excellent corrosion resistance and a coated metal plate using the same, and more specifically, in the case of a non-chromium coating composition, not only the corrosion resistance of the flat portion of the coated metal plate but also the processed part. In particular, the present invention relates to a coating composition effective for improving the corrosion resistance of an end face and a coated metal plate using the same.

  Conventionally, pre-coated metal sheets such as pre-coated steel sheets painted by coil coating, etc., building materials such as roofs, walls, shutters, garages, various household appliances, switchboards, refrigerated showcases, steel furniture, kitchen appliances, etc. Widely used as a housing related product.

  In order to manufacture these housing-related products from a pre-coated metal plate, the pre-coated steel plate is usually cut, press-molded and joined. Therefore, these housing-related products often have a metal exposed portion that is a cut surface and a crack generating portion due to press working. The exposed metal part and cracking part are more likely to have a lower corrosion resistance than other parts, so it is common to include a chromium-based rust-preventive pigment in the precoat steel base coat to improve corrosion resistance. Has been done.

  However, chromium-based rust preventive pigments contain or produce hexavalent chromium having excellent rust prevention properties, and the use of this hexavalent chromium has been restricted from the viewpoint of human health and environmental protection. ing.

  To date, many non-chromium anticorrosive pigments such as zinc phosphate, aluminum tripolyphosphate, and zinc molybdate have been put on the market, and various primers have been proposed as a combination of non-chromium pigments. ing. For example, Patent Document 1 discloses a combination of epoxy resin and phenol resin vehicle components, a combination of calcium silicate and phosphorus vanadate, and a combination of calcium carbonate, calcium silicate, aluminum phosphate, and phosphorus vanadate as antirust pigments. A paint containing a rust preventive pigment is described. Patent Document 2 describes a paint in which polyester is combined with a combination of a second magnesium phosphate and a fired product of manganese oxide / vanadium oxide or a fired product of calcium phosphate and vanadium oxide as a rust preventive pigment. Yes. However, the coating film formed from the paint described in Patent Documents 1 and 2 is inferior in corrosion resistance as compared with a paint using a chromium pigment, and in particular, the corrosion resistance in the processed part and the end face part is insufficient. . In addition, chemical resistance such as alkali resistance and acid resistance is often inferior. Further, when a large amount of rust preventive pigment is used, the water resistance is often inferior, and it has not yet been replaced by chromium-based rust preventive pigments in the production of precoated metal sheets.

  Patent Document 3 discloses that a vehicle component composed of an organic resin containing a hydroxyl group or an epoxy group and a curing agent has an oil absorption of 30 to 200 ml / 100 g and a pore volume of 0.05 to 1.2 ml / g. A coating composition containing a silica fine particle and having a glass transition temperature of 40 to 125 ° C. of a cured coating film formed from the coating is described. However, although the coating film formed from the paint described in Patent Document 3 shows considerable corrosion resistance, it is still inferior in corrosion resistance and chemical resistance compared to a paint using a chromium-based pigment. Insufficient corrosion resistance.

Japanese Patent Laid-Open No. 11-61001 JP 2000-199078 A JP 2000-129163 A

  The object of the present invention is to prevent the formation of a coating film excellent in the corrosion resistance of the processed part and the end face part as well as the general part of the coated metal plate, even in the case of a non-chromium rust-proof coating composition. A rust coating composition and a coated metal plate using the same are provided.

  Therefore, as a result of intensive studies to solve the above-mentioned problems, the present inventors contain a bisphenol type epoxy resin modified with an aliphatic polybasic acid and an acrylic resin, a crosslinking agent, and a rust preventive pigment. The present invention has been completed by finding that the coating composition can form not only the corrosion resistance of the flat portion but also the coating portion excellent in the corrosion resistance of the processed portion and the end surface portion of the coated metal plate.

In other words, the present invention provides “1. (A) a hydroxyl group-containing polyester resin having a glass transition temperature of −20 to 50 ° C. and a hydroxyl value of 20 to 100 mg KOH / g and a number average molecular weight of 2,000 to 30,000. A film-forming resin, (B) a resin obtained by reacting a soft organic component and a bisphenol type epoxy resin, and a soft organic component based on a total of 100 parts by mass of both the soft organic component and the bisphenol type epoxy resin reacting the range from 1 to 50 parts by weight of a bisphenol type epoxy resin 99 to 50 parts by weight comprising a soft organic component modified bisphenol epoxy resin, a curing agent (C) and (D) a non-chromium anticorrosive pigments a coating composition containing, the resin (a), the based on the total 100 parts by weight of the solid content of the resin (B) and curing agent (C), the resin (a There 5-90 parts by weight 5 to 90 parts by weight of the resin (B) is a curing agent (C) is in the range of 5 to 45 parts by weight, and a soft organic component in the resin (B), 4 carbon atoms -36 aliphatic polybasic acid, an acrylic resin having a glass transition temperature of -20 to 50 ° C. and an acid value of 5 to 40 mg KOH / g having a carboxyl group as a reactive group that reacts with an epoxy group, and a glass transition temperature of − A chromium-based rust preventive pigment characterized by being at least one of polyester resins having an acid value of 5 to 70 mgKOH / g having a carboxyl group as a reactive group that reacts with an epoxy group at 20 to 50 ° C Anti-corrosion paint composition not containing
2. The anticorrosive coating composition according to item 1, wherein the aliphatic polybasic acid having 4 to 36 carbon atoms is dimer acid,
3. Item 3. The rust preventive coating composition according to Item 1 or 2, wherein the curing agent (C) is at least one crosslinking agent among an amino resin, a phenol resin, and a polyisocyanate compound which may be blocked. The rust preventive pigment (D) contains (1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate, and (2) at least one silicon of metal silicate and silica fine particles. The antirust coating composition according to any one of the above items 1 to 3, which comprises a compound and (3) a phosphate metal salt,
5. A cured coating film based on the coating composition according to any one of the above items 1 to 4 is formed on one or both surfaces of a metal plate that may be subjected to chemical conversion treatment on the surface. Painted metal plate,
6). A cured coating film based on the coating composition according to any one of the above items 1 to 4 is formed on one surface or both surfaces of a metal plate, the surface of which may be subjected to chemical conversion treatment. A coated metal plate having a multilayer coating film formed by forming a top coating film on at least one surface. ".

As an embodiment of the present invention,
[A. The rust preventive coating composition according to item 5, wherein the silicon-containing compound (2) is a metal silicate of a metal selected from calcium, magnesium, and zinc.

B. The anticorrosive pigment (C) contains (1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate, (2) at least one silicon of metal silicate and silica fine particles. Containing a compound and (3) a phosphoric acid metal salt, with respect to 100 parts by mass of the total solid content of the resin (A) and the crosslinking agent (B),
3 to 50 parts by mass of the vanadium compound (1),
The amount of the silicon-containing compound (2) is 3 to 50 parts by mass, and the amount of the phosphate metal salt (3) is 3 to 50 parts by mass, and the compound (1), the compound (2) and the salt The total amount of (3) is 10 to 150 parts by mass, the rust preventive coating composition according to item 5 above,
C. The coating composition according to item 1, further comprising at least one pigment component of titanium dioxide pigment and extender pigment,
D. Furthermore, the coating composition of said claim | item 1 containing at least 1 sort (s) of a ultraviolet absorber and a ultraviolet stabilizer. ".

  The coating composition of the present invention is not only excellent in the corrosion resistance of the flat portion even when it does not contain a chromium-based anticorrosive pigment, but also a painted metal plate that has been difficult to achieve with non-chromium anticorrosive paints, etc. The effect that the coating film excellent in the corrosion resistance of the processed part and the end face part can be formed.

  The coated metal plate on which the cured coating film based on the coating composition of the present invention is formed has excellent corrosion resistance at the flat portion, processed portion and end face portion, and even when it does not contain a chromium-based rust preventive pigment, strontium It has corrosion resistance equivalent to or better than a coated metal plate on which a cured coating film based on a paint using a conventional chromate rust preventive pigment such as chromate is formed.

  A coated metal plate in which a cured coating film based on the coating composition of the present invention is formed, and a top coating film is formed on the cured coating film, is excellent in the corrosion resistance of the flat portion, the processed portion, and the end surface portion. When using a zinc alloy-plated steel sheet such as a zinc-plated steel sheet or an aluminum-zinc alloy-plated steel sheet as a metal plate to be coated, by coating the coating composition of the present invention, not only the flat surface part but also the end surface part, Excellent corrosion resistance can be obtained even in the processed portion.

  The coating composition of the present invention comprises a hydroxyl group-containing film-forming resin (A), a bisphenol type epoxy resin (B) modified with a soft organic component, a curing agent (C), and a rust preventive pigment (D). It is a thing.

Hydroxyl-containing film-forming resin (A)
The hydroxyl group-containing film-forming resin (A) in the coating composition of the present invention is at least one hydroxyl group-containing film-forming resin of acrylic resin and polyester resin.

  As said hydroxyl-containing acrylic resin, what has a hydroxyl group in the frame | skeleton can be used, and it is obtained by copolymerizing a hydroxyl-containing polymerizable unsaturated monomer and the other monomer copolymerizable with this monomer. Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, hydroxyethyl vinyl ether, ω-hydroxybutyl vinyl ether, ω-hydroxybutyl (meth) acrylate, and the like. Is mentioned.

  Monomers that can be copolymerized with a hydroxyl group-containing polymerizable unsaturated monomer include carboxyl group-containing polymerizable unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid; methyl (meth) acrylate, ethyl (meth) acrylate, Alkyl esters of acrylic acid or methacrylic acid such as propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate; ethyl vinyl ether, butyl vinyl ether, etc. Alkyl vinyl ethers of styrene, vinyl toluene, vinyl acetate, acrylonitrile and the like.

  In the present specification, “(meth) acrylate” means “acrylate or methacrylate”.

  The hydroxyl group-containing acrylic resin includes a modified acrylic resin such as a urethane-modified acrylic resin modified with a polyisocyanate compound. Examples of the polyisocyanate compound used for modification include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), 2,4, Examples thereof include 6-triisocyanatotoluene.

The hydroxyl group-containing acrylic resin that can be used as the hydroxyl group-containing film-forming resin (A) has a glass transition temperature of −15 ° C. to 60 ° C., preferably −10 to 40 ° C., and has a hydroxyl value. 30 to 250 mg KOH / g resin, preferably 50 to 150 mg KOH / g resin. The hydroxyl group-containing acrylic resin preferably has a number average molecular weight of about 2,000 to 50,000, and more preferably 3,000 to 30,000.
In the present specification, the glass transition temperature of the resin is measured by scanning differential thermal analysis. In the present specification, the average molecular weight of the resin is a value calculated based on the molecular weight of standard polystyrene from the chromatogram measured by gel permeation chromatography. As the gel permeation chromatograph, “HLC8120GPC” (manufactured by Tosoh Corporation) was used. As the columns, four columns of “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation, trade name) were used, Mobile phase: Tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: under the conditions of RI.

  The hydroxyl group-containing polyester resin that can be used as the hydroxyl group-containing film-forming resin (A) is a polyester resin having a hydroxyl group in the molecule, and is an oil-free polyester resin, an oil-modified alkyd resin, or a modified product of these resins. Examples thereof include urethane-modified polyester resins and urethane-modified alkyd resins.

  The oil-free polyester resin is an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one or more selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, monobasic acids such as benzoic acid, crotonic acid, pt-butylbenzoic acid, trimellitic anhydride, methylcyclohexentricarboxylic acid , Tribasic or higher polybasic acids such as pyromellitic anhydride are used in combination. Examples of the polyhydric alcohol component include bivalent compounds such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, and 1,6-hexanediol. Alcohol is mainly used, and a trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol can be used in combination as necessary. These polyhydric alcohols can be used alone or in admixture of two or more. The esterification or transesterification reaction of both components can be carried out by a method known per se. As the acid component, isophthalic acid, terephthalic acid, and lower alkyl esterified products of these acids are particularly preferable.

  In addition to the acid component and alcohol component of the oil-free polyester resin, the alkyd resin is obtained by reacting an oil fatty acid by a method known per se. Examples of the oil fatty acid include coconut oil fatty acid, soybean oil fatty acid, Examples thereof include linseed oil fatty acid, safflower oil fatty acid, tall oil fatty acid, dehydrated castor oil fatty acid, and kiri oil fatty acid. The oil length of the alkyd resin is preferably 30% or less, particularly about 5 to 20%.

  As the urethane-modified polyester resin, the oil-free polyester resin or the low-molecular weight oil-free polyester resin obtained by reacting an acid component and an alcohol component used in the production of the oil-free polyester resin, a polyisocyanate compound and Examples thereof include those reacted by a method known per se. The urethane-modified alkyd resin is obtained by reacting the alkyd resin or a low molecular weight alkyd resin obtained by reacting each component used in the production of the alkyd resin with a polyisocyanate compound by a method known per se. Things are included. Polyisocyanate compounds that can be used in the production of urethane-modified polyester resins and urethane-modified alkyd resins include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4 ′. -Methylenebis (cyclohexyl isocyanate), 2,4,6-triisocyanatotoluene and the like. In general, as the urethane-modified resin, those having a modification degree such that the amount of the polyisocyanate compound forming the urethane-modified resin is 30% by weight or less with respect to the urethane-modified resin can be preferably used.

  Among the polyester resins described above, particularly preferred are oil-free polyester resins.

  The hydroxyl group-containing polyester resin that can be used as the hydroxyl group-containing film-forming resin (A) has a glass transition temperature of −20 ° C. to 50 ° C., preferably −10 to 40 ° C., and a hydroxyl value of 20 to 100 mgKOH / g resin. The number average molecular weight is preferably about 2,000 to 30,000, and more preferably 3,000 to 20,000, preferably in the range of 30 to 80 mg KOH / g resin.

  The hydroxyl group-containing film-forming resin (A) can form a tough crosslinked structure while reducing internal stress by adjusting the glass transition temperature and the hydroxyl value within the above range. It is thought that it contributes to the demonstration of

Bisphenol type epoxy resin modified with soft organic components (B)
The bisphenol-type epoxy resin (B) modified with the soft organic component in the coating composition of the present invention (hereinafter sometimes abbreviated as “modified resin (B)”) reacts the soft organic component with the bisphenol-type epoxy resin. It is resin made to let.

  The soft organic component is an organic component that has a functional group that reacts with a bisphenol-type epoxy resin and can plasticize the bisphenol-type epoxy resin, and has an aliphatic polybasic acid having 4 to 36 carbon atoms and a glass transition temperature of −20. It is at least 1 sort (s) of the acrylic resin of -50 degreeC, and the polyester resin whose glass transition temperature is -20-50 degreeC.

  The polyester resin includes both oil-free polyester resins and oil-modified polyester resins, and may be modified polyester resins such as silicon-modified polyester resins and urethane-modified polyester resins.

  The aliphatic polybasic acid having 4 to 36 carbon atoms is a saturated or unsaturated aliphatic polybasic acid having 4 to 36 carbon atoms, preferably 8 to 36, including alicyclic polybasic acids, For example, hexahydroisophthalic acid, hexahydroterephthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, methylhexahydroterephthalic acid, Δ1-tetrahydrophthalic acid, Δ2-tetrahydrophthalic acid, Δ3-tetrahydrophthalic acid, Δ4-tetrahydrophthalic acid, Δ1-tetrahydroisophthalic acid, Δ2-tetrahydroisophthalic acid, Δ3-tetrahydroisophthalic acid, Δ4-tetrahydroisophthalic acid, Δ1-tetrahydroterephthalic acid, Δ2-tetrahydroterephthalic acid, methyl Tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, methyl endomethy Cycloaliphatic acid, hexachloroendomethylenetetrahydrophthalic acid and other alicyclic dicarboxylic acids and their anhydrides; succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dodecanedicarboxylic acid, suberic acid, pimelin Aliphatic dicarboxylic acids such as acid, maleic acid, fumaric acid, itaconic acid, brassic acid, citraconic acid, chloromaleic acid and dimer acid and their anhydrides; trivalent or higher aliphatic polybasic acids such as hexahydrotrimellitic acid Lower alkyl esters such as methyl esters and ethyl esters of these acids;

  Examples of the acrylic resin that can be used as the soft organic component in the production of the modified resin (B) include an acrylic resin having a reactive group that reacts with the epoxy group of the bisphenol-type epoxy resin. The acrylic resin includes a modified acrylic resin such as a urethane-modified acrylic resin. Examples of the reactive group include a carboxyl group, an amino group, a hydroxyl group, and the like. Among the acrylic resins, an acrylic resin having a carboxyl group is preferably used.

  The acrylic resin having a carboxyl group is obtained by copolymerizing a polymerizable unsaturated monomer having a carboxyl group and other polymerizable unsaturated monomers by a known method such as a solution polymerization method, a suspension polymerization method, or a bulk polymerization method. Among them, the solution polymerization method is preferable from the viewpoint of easy control of the polymerization. The other polymerizable unsaturated monomer contains a (meth) acrylic acid ester. It is preferable that the amount of (meth) acrylic acid ester used is in the range of 30 to 98% by mass based on the total amount of copolymerization monomer components constituting the modified resin (B).

  Examples of the polymerizable unsaturated monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid.

  Examples of the other polymerizable unsaturated monomers include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and ε-caprolactone modified. Tetrahydrofurfuryl (meth) acrylate, ε-caprolactone modified hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- Hydroxyl group-containing polymerizable unsaturated monomers such as hydroxy-3-butoxypropyl (meth) acrylate and monohydroxyethyl (meth) acrylate phthalate; methyl (meth) acrylate , Ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate Alkyl (meth) acrylates such as tridecyl (meth) acrylate; cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate; benzyl (meth) acrylate, phenyl (meth) acrylate; dimethylaminoethyl (meth) acrylate, diethylaminoethyl Di (alkyl) aminoalkyl (meth) acrylates such as (meth) acrylate; glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ester Epoxy group-containing polymerizable unsaturated monomers such as ter; vinyl aromatic compounds such as styrene, α-methyl styrene and vinyl toluene; acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, acrylamide, methacrylamide, methylol acrylamide, methylol methacryl Amide, diacetone acrylamide, acryloyl morpholine, N-vinyl-2-pyrrolidone, γ-acryloxypropyltrimethoxylane, γ-methacryloxypropyltrimethoxylane, vinyl chloride, propylene, ethylene, C4 to C20 α- Examples include olefins. These can be used alone or in combination of two or more.

  In the present specification, “(meth) acrylate” means “acrylate or methacrylate”.

The number average molecular weight of the acrylic resin is preferably in the range of 2000 to 40000, particularly 3000 to 30000 when it is synthesized by solution polymerization from the viewpoint of compatibility with the bisphenol type epoxy resin and reactivity. .
The acrylic resin preferably has an acid value of 3 to 50 mgKOH / g, particularly 5 to 40 mgKOH / g, from the viewpoints of reactivity and adhesion to the bisphenol type epoxy resin. The hydroxyl value of the acrylic resin is preferably 10 to 300 mgKOH / g, particularly preferably 30 to 250 mgKOH / g, from the viewpoint of the curability and water resistance of the coating film. Furthermore, the glass transition temperature (Tg) of the acrylic resin is preferably in the range of −20 ° C. to 50 ° C., preferably in the range of −20 ° C. to 40 ° C. It is.

  Examples of the polyester resin that can be used as the soft organic component in the production of the modified resin (B) include polyester resins having a reactive group that reacts with the epoxy group of the bisphenol-type epoxy resin. The polyester resin includes both oil-free polyester resins and oil-modified polyester resins, and may be modified polyester resins such as silicon-modified polyester resins and urethane-modified polyester resins. Examples of the reactive group include a carboxyl group, an amino group, a hydroxyl group, and the like, and a polyester resin having a carboxyl group is particularly preferably used as the polyester resin.

  Among the polyester resins, the oil-free polyester resin can be produced using a known method such as a direct esterification method, a transesterification method, or a ring-opening polymerization method. Specific examples of the direct esterification method include a method of polycondensation of a polybasic acid and a polyhydric alcohol. As the polybasic acid, one or more dibasic acids selected from phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, fumaric acid, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc .; Tribasic acid or more polybasic acid such as trimellitic anhydride, methylcyclohexylic carboxylic acid, pyromellitic anhydride, etc. is used, and benzoic acid, crotonic acid, p-tertbutylbenzoic acid, etc. are used as the acid component as required. Monobasic acids can also be used. As the polyhydric alcohol, dihydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, butanediol, neopentyl glycol, hexanediol and 1,6-hexanediol are mainly used. A trihydric or higher polyhydric alcohol such as methylolethane, trimethylolpropane and pentaerythritol can also be used in combination.

  The production of the carboxyl group-containing polyester resin can be carried out by a known method in a compounding ratio in which the acid group is excessive with respect to the hydroxyl group of the polybasic acid and the polyhydric alcohol. It can also be carried out by post-adding a polybasic acid such as trimellitic anhydride or phthalic anhydride to the hydroxyl group.

  The oil-free polyester resin can also be produced by polycondensation by transesterification between a polybasic acid lower alkyl ester and a polyhydric alcohol. Furthermore, the oil-free polyester resin can also be produced by ring-opening polymerization of lactones such as δ-valerolactone and ε-caprolactone.

  Of the polyester resins, an oil-modified polyester resin is obtained by reacting an oil fatty acid with the oil-free polyester resin. Examples of the oil fatty acid include coconut oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, safflower oil. Fatty acid, tall oil fatty acid, dehydrated castor oil fatty acid, tung oil fatty acid and the like can be mentioned, and the reaction between the polyester resin and the oil fatty acid can be carried out by a known method, and the oil length is usually preferably 30% or less.

  The weight average molecular weight of the polyester resin is preferably in the range of 1000 to 30000, particularly 2000 to 20000, from the viewpoints of compatibility with the bisphenol type epoxy resin and reactivity. The acid value of the polyester resin is preferably from 3 to 100 mgKOH / g, particularly preferably from 5 to 70 mgKOH / g, from the viewpoints of reactivity and adhesion to the bisphenol-type epoxy resin. The glass transition temperature (Tg) of the polyester resin is preferably in the range of −20 ° C. to 50 ° C., preferably −20 ° C. to 40 ° C., from the viewpoint of the balance between the workability and hardness of the resulting coating film. It is.

  The bisphenol-type epoxy resin used in the production of the modified resin (B) is a bisphenol-type epoxy resin having one or more, preferably two or more epoxy groups in one molecule. For example, epichlorohydrin and bisphenol are added as necessary. A resin obtained by condensing to a high molecular weight in the presence of a catalyst such as an alkali catalyst, epichlorohydrin and bisphenol may be condensed in the presence of a catalyst such as an alkali catalyst as necessary to form a low molecular weight epoxy resin. Any of resins obtained by polyaddition reaction of a low molecular weight epoxy resin and bisphenol may be used.

  The bisphenol-type epoxy resin usually has a number average molecular weight of 350 to 5000, preferably 400 to 4000, and an epoxy group content of 0.5 to 15.4 mmol / g, preferably 0.8 to 10 mmol / g is preferred.

  Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2, 2-bis (4-hydroxyphenyl) butane [bisphenol B], bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis ( 2-hydroxy-tert-butyl-phenyl) -2-hydroxy-1,3-oxy-propane, p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4'-dihydroxybenzophenone, bis (2-hydroxynaphth Le), etc. can be mentioned methane, bisphenol A, bisphenol F are preferably used among others. The bisphenols can be used alone or as a mixture of two or more.

  Examples of commercially available bisphenol type epoxy resins include Epicoat 828, 812, 815, 820, 834, 1001, 1004, 1007, 1009, 1010, and 4004P manufactured by Japan Epoxy Resin. 4007P and 4210; Araldite AER6099 manufactured by Asahi Ciba; and Epomic R-309 manufactured by Mitsui Chemicals.

  The method for producing the modified resin (B) by reacting the soft organic component with the bisphenol type epoxy resin is not particularly limited. For example, when two types of soft organic components are used, a method in which two types of soft organic components and a bisphenol type epoxy resin are simultaneously reacted together, one type of soft organic component and a bisphenol type epoxy resin are reacted. Examples of the method include a method of reacting the remaining soft organic components after the reaction.

  The above reaction can be suitably performed by, for example, reacting at 100 to 150 ° C. for about 1 to 5 hours in a solvent capable of dissolving these components, if necessary, in the presence of a reaction catalyst. .

  Examples of the reaction catalyst include quaternary salt catalysts such as tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylphosphonium bromide and triphenylbenzylphosphonium chloride; amines such as triethylamine and tributylamine Etc.

  In the above reaction, when the reactive group of the soft organic component is a carboxyl group, the equivalent ratio of (epoxy group in the bisphenol-type epoxy resin) / (carboxyl group in the soft organic component) is 10/1 to 1 / 1, preferably within the range of 5/1 to 2/1. When the acrylic resin has a reactive group that reacts with an epoxy group other than a carboxyl group in the synthesis reaction of the modified resin (B), the ratio of each reactive group is represented by the formula “carboxyl group in soft organic component”. "Is preferably within the range of the formula in which" reactive group reacting with an epoxy group other than a carboxyl group "is substituted.

The blending ratio of the soft organic component and the bisphenol type epoxy resin when producing the modified resin (B) is preferably within the following range based on a total of 100 parts by mass of both.
Soft organic component: 1-50 parts by weight, preferably 5-40 parts by weight,
Bisphenol type epoxy resin: 50 to 99 parts by mass, preferably 60 to 95 parts by mass.

Moreover, when manufacturing modified resin (B), when using together an aliphatic polybasic acid and a soft resin component (acrylic resin and / or polyester resin) as a soft organic component, when manufacturing modified resin (B). The blending ratio of the aliphatic polybasic acid, the soft resin component, and the bisphenol type epoxy resin is preferably within the following range based on the total of 100 parts by mass.
Aliphatic polybasic acid: 0.5-30 parts by mass, preferably 2-25 parts by mass Soft resin component: 0.5-49 parts by mass, preferably 3-38 parts by mass Bisphenol type epoxy resin: 50-99 parts by mass , Preferably 60 to 95 parts by mass.

  Furthermore, the modified resin (B) is a sequestering agent such as benzoic acid, salicylic acid or a secondary amine compound in order to block the epoxy group when the epoxy group remains after reacting the soft organic component and the bisphenol type epoxy resin. May be reacted. Moreover, depending on the case, a blocking agent can also be made to react at the time of reaction of a soft organic component and a bisphenol-type epoxy resin.

  It is considered that the modified resin (B) has a soft component in the structure, thereby contributing to the development of stress relaxation ability of the crosslinked coating film and contributing to improvement of workability and processed part adhesion.

Curing agent (C)
The curing agent (C) reacts with the hydroxyl group-containing film-forming resin (A) and the bisphenol-type epoxy resin (B) modified with a soft organic component to form a cured coating film. Any material that can be cured by reacting with (A) and the resin (B) can be used without particular limitation. As the curing agent (C), amino resins, phenol resins and polyisocyanate compounds which may be blocked are particularly suitable. These curing agents can be used alone or in combination of two or more.

  Examples of the amino resin include methylolated amino resins obtained by reacting an amino component such as melamine, urea, benzoguanamine, acetogranamamine, steroguanamine, spiroguanamine, and dicyandiamide with an aldehyde. Examples of the aldehyde used in the reaction include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Moreover, what etherified the said methylolated amino resin with suitable alcohol can also be used as an amino resin. Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

  The phenol resin that can be used as the curing agent is a part of the methylol group of the methylolated phenol resin obtained by introducing a methylol group by heating and condensation reaction of a phenol component and formaldehyde in the presence of a reaction catalyst, or A resol type phenolic resin obtained by alkylating all of them with an alcohol is exemplified.

  In the production of a resol-type phenol resin, a bifunctional phenol compound, a trifunctional phenol compound, a tetrafunctional or higher functional phenol compound, or the like can be used as the phenol component as a starting material.

  Examples of the phenol compound include, for example, bifunctional phenol compounds such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, and 2,5-xylenol. Examples of the trifunctional phenol compound include carboxylic acid, m-cresol, m-ethylphenol, 3,5-xylenol, and m-methoxyphenol. Examples of the tetrafunctional phenol compound include bisphenol A and bisphenol F. Can be mentioned. Among them, in order to improve scratch resistance, it is preferable to use a trifunctional or higher functional phenol compound, in particular, carboxylic acid and / or m-cresol. These phenol compounds may be used alone or in combination of two or more.

  Examples of formaldehydes used in the production of phenol resins include formaldehyde, paraformaldehyde, trioxane, and the like, which can be used alone or in combination of two or more.

  As the alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin, a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, can be suitably used. Suitable monohydric alcohols include methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.

  The phenol resin has an average of 0.5 or more, preferably 0.6 to 3.0 alkoxymethyl groups per nucleus of the benzene nucleus in view of reactivity with the resin (A) or the resin (B). Things are suitable.

  Examples of the unblocked polyisocyanate compound that can be used as the curing agent as the curing agent include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; hydrogenated xylylene diisocyanate or Cycloaliphatic diisocyanates such as isophorone diisocyanate; organic diisocyanates per se such as tolylene diisocyanate, xylylene diisocyanate or 4,4'-diphenylmethane diisocyanate, aromatic diisocyanates such as crude MDI, or each of these organic diisocyanates and polyvalent Adducts with alcohol, low molecular weight polyester resin or water, or as described above Cyclic polymerization of an organic diisocyanate comrades, further include isocyanate-biuret, or the like.

  The blocked polyisocyanate compound is obtained by blocking free isocyanate groups of the polyisocyanate compound with a blocking agent. Examples of the blocking agent include phenols such as phenol, cresol and xylenol; ε-caprolactam; lactones such as δ-valerolactam and γ-butyrolactam; methanol, ethanol, n-, i- or t-butyl alcohol, ethylene Alcohols such as glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; oximes such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime System: Active methylene such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, acetylacetone It can be suitably used blocking agent, such as. By mixing the polyisocyanate compound and the blocking agent, free isocyanate groups of the polyisocyanate compound can be easily blocked.

The mixing ratio of the hydroxyl group-containing film-forming resin (A), the modified resin (B), and the curing agent (C) is based on 100 parts by mass of the total solid content of the components (A), (B), and (C). In view of corrosion resistance, boiling water resistance, processability, curability, and the like, it is preferable that it is within the following range.
Resin (A): 5-90 parts by mass, preferably 10-80 parts by mass,
Resin (B): 5-90 parts by mass, preferably 10-80 parts by mass,
Curing agent (C): 5-45 parts by mass, preferably 10-40 parts by mass.

  In order to increase the curability of the coating composition of the present invention, a curing catalyst can be blended as necessary. When the curing agent (C) contains an amino resin, particularly a low molecular weight methyl etherified or mixed etherified melamine resin of methyl ether and butyl ether, a sulfonic acid compound or amine neutralization of the sulfonic acid compound as a curing catalyst A thing is used suitably. Representative examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. The amine in the amine neutralized product of the sulfonic acid compound may be any of primary amine, secondary amine, and tertiary amine. Among these, the amine neutralized product of p-toluenesulfonic acid and / or the amine neutralized product of dodecylbenzenesulfonic acid is preferable from the viewpoints of the stability of the coating, the reaction promoting effect, and the physical properties of the obtained coating film. .

  When the curing agent (C) is a phenol resin, the sulfonic acid compound or an amine neutralized product of the sulfonic acid compound is preferably used as the curing catalyst.

  When the curing agent (C) is a blocked polyisocyanate compound, a curing catalyst that promotes dissociation of the blocking agent of the blocked polyisocyanate compound, which is a curing agent, is suitable. As a suitable curing catalyst, for example, octyl Tin oxide, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, lead 2-ethylhexanoate And organometallic catalysts such as

  When the curing agent (C) is a combination of two or more crosslinking agents, an effective curing catalyst can be used in combination with each curing agent.

Antirust pigment (D)
As the rust preventive pigment (D), any chrome pigment or non-chromium pigment can be used as long as it has a rust preventive property. However, non-chromium is used from the viewpoint of human health and environmental protection. It is preferable to be a pigment.

  Examples of the chromium-based rust preventive pigment include strontium chromate, zinc chromate, zinc potassium chromate, barium chromate, chromium chromate, and chromium phosphate. Non-chromium rust preventive pigments include zinc phosphate, aluminum tripolyphosphate, calcium molybdate silicate, vanadium pentoxide, calcium vanadate, ammonium metavanadate, phosphorus vanadate, aluminum phosphate, calcium phosphate, dibasic magnesium phosphate, Examples thereof include calcined products of manganese oxide and vanadium oxide, calcined products of calcium phosphate and vanadium oxide, silica fine particles having an oil absorption of 30 to 200 ml / 100 g, and a pore volume of 0.05 to 1.2 ml / g. it can. These rust preventive pigments can be used alone or in combination of two or more.

  In the coating composition of the present invention, as the anticorrosive pigment (D), among others, a combination of the following (1) vanadium compound, (2) silicon-containing compound and (3) phosphate metal salt can be preferably used.

Vanadium compound (1)
The vanadium compound (1) is at least one vanadium compound selected from vanadium pentoxide, calcium vanadate, and ammonium metavanadate. Vanadium pentoxide, calcium vanadate and ammonium metavanadate are excellent in elution of pentavalent vanadium ions into water, and the pentavalent vanadium ions released from the vanadium compound (1) react with the material metal, It works effectively to improve corrosion resistance by reacting with ions from other antirust pigment mixtures.

Silicon-containing compound (2)
The silicon-containing compound (2) is at least one of metal silicate and silica fine particles.

  The metal silicate is a salt made of silicon dioxide and a metal oxide, and may be any of orthosilicate, polysilicate, and the like. Examples of the silicate include zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, aluminum calcium silicate, sodium aluminum silicate, beryllium aluminum silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, calcium calcium silicate, and silicic acid. Zirconium, magnesium orthosilicate, magnesium metasilicate, magnesium calcium silicate, manganese silicate, barium silicate, olivine, garnet, tortovite, cyllite, benitoite, neptunite, nymphite, turquoise, quartzite, barracite, tosen Stones, zonotorite, talc, gyoganite, aluminosilicate, borosilicate, beryllosilicate, cholite, fluorite and the like. Among them, calcium orthosilicate and calcium metasilicate are preferable as the metal silicate.

  The silica fine particles can be used without any limitation as long as they are silica fine particles. For example, silica fine powder whose surface is not treated, silica fine powder whose surface is treated with organic matter, calcium ion-exchanged silica fine particles, organic solvent-dispersible colloidal silica And so on.

  Examples of the silica fine particles whose surface is not treated or treated with an organic substance include silica fine powder having an average particle size of 0.5 to 15 μm, preferably 1 to 10 μm, and organic solvent-dispersible colloidal silica. As the fine silica powder, those having an oil absorption of 30 to 350 ml / 100 g, preferably 30 to 150 ml / 100 g can be suitably used, and as commercially available products, silicia 710, silicia 740, silicia 550, Examples include Aerosil R972 (all of which are manufactured by Fuji Silysia Chemical Co., Ltd.), Mizukacil P-73 (manufactured by Mizusawa Chemical Industry Co., Ltd.), Gasil 200DF (manufactured by Crossfield).

  Calcium ion exchanged silica is silica fine particles in which calcium ions are introduced into a fine porous silica carrier by ion exchange. Examples of commercially available calcium ion exchanged silica include SHIELDEX (Shielddex, registered trademark) C303, AC-3, AC-5 (all of which are manufactured by WR Grace & Co.). it can. Calcium ions released from calcium ion exchanged silica are involved in electrochemical action and various salt forming actions, and effectively work to improve corrosion resistance. Moreover, the silica fixed in the coating film effectively works to suppress peeling of the coating film in a corrosive atmosphere. The organic solvent-dispersible colloidal silica is also called an organosilica sol, in which silica fine particles having a particle size of about 5 to 120 nm are stably dispersed in an organic solvent such as alcohols, glycols, and ethers. Examples of commercially available products include the OSCAL series (manufactured by Catalyst Kasei Co., Ltd.) and organosols (manufactured by Nissan Chemical Co., Ltd.). Of these, calcium ion exchanged silica fine particles are preferred.

Each metal silicate and each silica fine particle can be used as a silicon-containing compound (2) by 1 type or in combination of 2 or more types.
Phosphate metal salt (3)
The phosphoric acid metal salt (3) is at least one of a phosphoric acid metal salt, a hydrogen phosphate metal salt, and a tripolyphosphate metal salt. The metal of the phosphate metal salt is not particularly limited, and examples of suitable metals include Ca, Zn, Al, and Mg. Among these, Ca is particularly suitable.

  Examples of the phosphate metal salt include calcium phosphate, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate phosphate, zinc phosphate, aluminum phosphate, magnesium phosphate, hydrogen phosphate Examples thereof include zinc, aluminum phosphate, magnesium phosphate, aluminum hydrogen phosphate, magnesium hydrogen phosphate, magnesium ammonium phosphate, and aluminum dihydrogen triphosphate. Of these, calcium phosphate, calcium monohydrogen phosphate, and calcium dihydrogen phosphate are particularly preferred from the viewpoint of corrosion resistance. Phosphate ions released from the phosphate metal salt (3), metal ions such as Ca, Zn, Al, or Mg effectively work to improve corrosion resistance.

  In the coating composition of the present invention, the total solid content of 100 parts by mass of the hydroxyl group-containing film-forming resin (A), the bisphenol-type epoxy resin (B) modified with a soft organic component, and the curing agent (C), The amount of the rust preventive pigment (D) is 10 to 150 parts by mass, preferably 15 to 90 parts by mass, from the viewpoint of corrosion resistance. Among them, as the rust preventive pigment (D), the vanadium compound (1), silicon It is preferred that the containing compound (2) and the phosphoric acid metal salt (3) are within the following ranges because they are non-chromic and improve corrosion resistance.

Vanadium compound (1): 3 to 50 parts by mass, preferably 5 to 30 parts by mass,
Silicon-containing compound (2): 3 to 50 parts by mass, preferably 5 to 30 parts by mass,
Phosphate metal salt (3): 3 to 50 parts by mass, preferably 5 to 30 parts by mass.

  In the coating composition of the present invention, the corrosion resistance can be synergistically improved by combining a predetermined amount of these (1), (2) and (3) as an antirust pigment mixture.

  In the coating composition of the present invention, in addition to the hydroxyl group-containing film-forming resin (A), the modified resin (B), the curing agent (C), the rust preventive pigment (D), and a curing catalyst blended as necessary, the coating composition Colored pigments, extender pigments, UV absorbers, UV stabilizers, organic solvents, additives such as anti-settling agents, antifoaming agents, and coating surface modifiers that can be used in the field can be blended as necessary.

  Examples of the colored pigment include organic colored pigments such as cyanine blue, cyanine green, organic red pigments such as azo and quinacridone; and inorganic colored pigments such as titanium white, titanium yellow, bengara, carbon black, and various fired pigments. Among them, titanium white can be preferably used.

  Examples of the extender pigment include talc, clay, mica, alumina, calcium carbonate, barium sulfate and the like.

  Examples of the ultraviolet absorber include 2- (2-hydroxy-3,5-di-t-amylphenyl) -2H-benzotriazole, isooctyl-3- (3- (2H-benzotriazol-2-yl)- 5-t-butyl-4-hydroxyphenylpropionate, 2- [2-hydroxy-3,5-di (1,1-dimethylbenzidine) phenyl] -2H-benzotriazole, 2- [2-hydroxy-3- Dimethylbenzyl-5- (1,1,3,3-tetramethylbutyl) phenyl] -2H-benzotriazole, methyl-3- [3-t-butyl-5- (2H-benzotriazol-2-yl)- Benzotriazole derivatives such as condensates with 4-hydroxyphenyl] propionate / polyethylene glycol 300; 2- [4- (2-hydroxy -3-dodecyloxypropyl) oxy] -2-triazine derivatives such as 2-hydroxyphenyl-4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine; ethanediamide-N- (2-ethoxy Succinic acid anilide such as phenyl) -N ′-(2-ethylphenyl)-(oxalic amide), ethanediamide-N- (2-ethoxyphenyl) -N ′-(4-isododecylphenyl)-(oxalic amide) System derivatives and the like.

  Examples of the ultraviolet stabilizer include, for example, hindered amine compounds, hindered phenol compounds; CHIMASORB 944, TINUVIN 144, TINUVIN 292, TINUVIN 770, IRGANOX 1010, IRGANOX 1098. Product)).

  By blending UV absorbers and UV stabilizers in the paint, it is possible to suppress the deterioration of the coating surface due to light. Even when this paint is used as a primer, it passes through the upper coating film and becomes a primer. Since the primer surface can be prevented from deteriorating due to light reaching the surface of the paint film, it can prevent delamination between the primer paint film and the upper paint film due to the deterioration of the primer paint film surface, providing excellent interlayer adhesion and corrosion resistance. Can be maintained.

  The organic solvent that can be blended in the coating composition of the present invention is blended as necessary to improve the paintability of the composition of the present invention, and includes a hydroxyl group-containing film-forming resin (A), a modified resin (B ) And the curing agent (C) can be used. Specifically, for example, hydrocarbon solvents such as toluene, xylene and high boiling petroleum hydrocarbons, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone Ketone solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ester solvents such as diethylene glycol monoethyl ether acetate, alcohol solvents such as methanol, ethanol, isopropanol, butanol, ethylene glycol monoethyl ether, ethylene Glycol mono Chirueteru, diethylene and ether alcohol-based solvents such as monobutyl ether can be exemplified, which may be used alone or in combination of two or more.

  In the coating composition of the present invention, the glass transition temperature of the cured coating film obtained from the composition of the present invention is 40 to 115 ° C, preferably 50 to 105 ° C, such as the corrosion resistance, acid resistance and workability of the coating film. To preferred. The glass transition temperature of the coating film is tan δ by temperature dispersion measurement at a frequency of 110 Hz using a DINAMIC VISCOELASTOMETER MODEL VIBRON (dynamic viscoelastometer model vibron) DDV-IIEA type (manufactured by Toyo Baldwin, automatic dynamic viscoelasticity measuring machine). It is the maximum temperature obtained from the change in.

  The coating film formed by coating the coating composition of the present invention on a metal plate exhibits excellent corrosion resistance. The reason for this is that the resin component in the coating composition of the present invention has a stress relaxation capability. This is considered to be due to the ability to form a coating film that is excellent and has an excellent balance between elastic modulus and elongation.

Painted metal plate The coating composition of the present invention can obtain a painted metal plate by coating and curing on a metal plate. As the metal plate to be coated, cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, iron-zinc alloy plated steel plate (galvanyl steel plate), aluminum-zinc alloy plated steel plate (containing about 55% aluminum in the alloy) Metal plate such as “galvanium steel plate”, “galfan” containing about 5% aluminum in the alloy), nickel-zinc alloy plated steel plate, stainless steel plate, aluminum plate, copper plate, copper plated steel plate, tin plated steel plate, etc. The surface of the metal plate may be subjected to chemical conversion treatment. Examples of the chemical conversion treatment include phosphate treatment such as zinc phosphate treatment and iron phosphate treatment, composite oxide film treatment, chromium phosphate treatment, and chromate treatment.

  The composition of the present invention can be coated on the metal plate by a known method such as a roll coating method, a curtain flow coating method, a spray method, a brush coating method, or a dipping method. Although the cured film thickness of the coating film obtained from this invention composition is not specifically limited, Usually, 2-10 micrometers, Preferably it is used in the range of 3-6 micrometers. Curing of the coating film may be appropriately set according to the type of resin used, etc., and when the material coated by the coil coating method is continuously baked, the material reached maximum temperature is usually 160 to 250 ° C. It is preferably baked for 15 to 60 seconds under the condition of 180 to 230 ° C. In the case of baking in a batch system, it can be carried out by baking at 80 to 200 ° C. for 10 to 30 minutes. In addition, in the case of a combination that does not particularly require heating for the crosslinking reaction in the coating film formation process, such as when a non-blocked polyisocyanate is used as the crosslinking agent (B), it is dried at room temperature according to a conventional method. It can also be cured.

  The coated metal plate of the present invention has a coating film formed of the above-described coating composition of the present invention on a metal plate which may be subjected to chemical conversion treatment, and the coated metal plate formed with the coating film of the present coating composition The coating itself can be used, but a top coating film can also be provided on this coating film. The film thickness of the top coat film is usually 8 to 30 μm, preferably 10 to 25 μm.

  Examples of the top coating material for forming the top coating film include various top coating materials such as polyester resin-based, alkyd resin-based, silicon-modified polyester resin-based, silicon-modified acrylic resin-based, and fluorine resin-based materials that are known for pre-coated steel sheets. be able to. When workability is particularly important, a coated steel sheet having particularly excellent workability can be obtained by using a polyester-based top coat for advanced processing. The coated metal plate of this invention can show the coating-film performance excellent in corrosion resistance.

  When using a galvanized steel plate or an aluminum-zinc alloy plated steel plate as the metal plate to be coated, the corrosion resistance of the flat surface has been considerably improved. Although the corrosion resistance was insufficient, by applying the coating composition of the present invention, excellent corrosion resistance can be obtained also in the end face part and the processed part.

  Moreover, the coating film by this invention coating composition may be provided in both surfaces of to-be-coated article, and the said top coating film is further formed on the coating film by this invention coating composition as needed. May be. By using a non-chromium rust preventive pigment that does not contain a chromium rust preventive pigment as the rust preventive pigment in the present paint composition, it is possible to obtain a coated metal plate that is advantageous in terms of environmental hygiene and excellent in corrosion resistance. it can.

  Hereinafter, the present invention will be described more specifically with reference to production examples and examples. The present invention is not limited to the following examples. Hereinafter, “parts” and “%” are based on mass.

Synthesis Example 1 Production of Hydroxyl-Containing Acrylic Resin AC1 Solution 100 parts of propylene glycol monomethyl ether was put into a reaction vessel equipped with a stirrer, thermometer and cooler, and the temperature in the reaction vessel was raised to 80 ° C. while stirring. . While maintaining the temperature at 80 ° C., a mixture of raw materials such as the monomers shown below was added dropwise over 3 hours, and the mixture was further aged at the same temperature for 3 hours to obtain a hydroxyl group-containing acrylic resin AC1 solution having a solid content of 35%. .
2-hydroxyethyl acrylate 15.0 parts 2-hydroxyethyl methacrylate 11.0 parts styrene 20.0 parts methyl methacrylate 27.0 parts n-butyl acrylate 27.2 parts 2,2′-azobisisobutyronitrile 1 .5 parts propylene glycol monomethyl ether 85.7 parts Synthesis Examples 2-8
Synthesis was carried out in the same manner as in Synthesis Example 1 except that the monomer composition was as shown in Table 1. Thus, hydroxyl group-containing acrylic resins AC2 to AC8 having a solid content of 35% were obtained. The hydroxyl group-containing acrylic resin AC8 solution is used as a soft organic component solution for producing a modified bisphenol type epoxy resin. Table 1 shows the property values of the resins obtained. All the compounding amounts in the table are indicated by solid mass.

Synthesis Example 9 Synthesis of Polyester Resin PE1 Solution The following raw material mixture was placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, etc., heated from 160 ° C. to 230 ° C. over 3 hours, and produced water Was distilled off through a rectification column. After maintaining at 230 ° C. for 1 hour, xylol was added, and dehydration was performed while refluxing the xylol at 230 ° C. to conduct an esterification reaction.
Ethylene glycol 0.9 mol Neopentyl glycol 0.1 mol Isophthalic acid 0.95 mol When the acid value reached about 0, it was cooled to 140 ° C. and held for 2 hours. After cooling, Swazol 1500 (Maruzen Petrochemical Co., Ltd.) Manufactured, high boiling aromatic petroleum solvent) was added to obtain a polyester resin PE1 solution having a solid content of 35%. The obtained resin had a number average molecular weight of 3,800, a glass transition temperature of 45 ° C., a hydroxyl value of 30 mgKOH / g, and an acid value of about 0 mgKOH / g.

Synthesis Examples 10 to 16
The synthesis was carried out in the same manner as in Synthesis Example 11 except that the alcohol component and the acid component were blended as shown in Table 1, and each polyester resin PE2 to PE8 solution having a solid content of 35% was obtained. Table 1 shows the property values of the resins obtained. All the compounding amounts in the table are expressed in terms of molar amounts.

  The polyester resins PE1 to PE7 are all hydroxyl group-containing polyester resins, and the polyester resin PE8 is a carboxyl group-containing polyester resin. The polyester resin PE8 solution is used as a soft organic component solution for producing a modified bisphenol type epoxy resin.

Production Example 1 Production of Modified Bisphenol Type Epoxy Resin ME1 Solution In a reaction vessel equipped with a stirrer and a heating / temperature control device, 43 parts of cyclohexanone, jER1004 (Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin, epoxy equivalent of about 925) 90 parts were charged and heated to 130 ° C. with stirring. After confirming that the epoxy resin was dissolved, 10 parts of dimer acid and 0.5 part of tetraethylammonium bromide were added, and the reaction was continued for 4 hours. After confirming that the resin acid value was 1 or less, 67.7 parts of cyclohexanone and 75 parts of SWAZOL 1000 (manufactured by Maruzen Petrochemical Co., Ltd., high boiling aromatic petroleum solvent) were added, and an epoxy having a solid content of 35% A resin ME1 solution was obtained.

Production Example 2
In Production Example 1, the same procedure as in Production Example 1 was carried out except that the amount of jER1004 was changed from 90 parts to 95 parts and the amount of dimer acid was changed from 10 parts to 5 parts, and a modified epoxy resin ME2 having a solid content of 35% A solution was obtained.

Production Example 3
In Production Example 1, the same procedure as in Production Example 1 was carried out except that the amount of jER1004 was changed from 90 parts to 80 parts and the amount of dimer acid was changed from 10 parts to 20 parts, and a modified epoxy resin ME3 having a solid content of 35% A solution was obtained.

Production Example 4
In Production Example 1, jER1004 was changed to jER1001 (Bisphenol A type epoxy resin manufactured by Japan Epoxy Resin Co., Epoxy Equivalent 475), and dimer acid was changed to adipic acid. The modified epoxy resin ME4 solution was obtained.

Production Example 5
In Production Example 1, jER1004 was changed to jER1007 (manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent of about 1800), and 10 parts of dimer acid was 29 parts of acrylic resin AC8 solution obtained in Synthesis Example 8 (solid content) The modified epoxy resin ME5 solution having a solid content of 35% was obtained in the same manner as in Production Example 1 except that the amount was changed to 10 parts.

Production Example 6
Production Example 1 except that 90 parts of jER1004 was changed to 80 parts of jER1007, and instead of 10 parts of dimer acid, 57 parts of the polyester resin PE8 solution obtained in Synthesis Example 16 (20 parts in solid content) was used. In the same manner as in Example 1, a modified epoxy resin ME6 solution having a solid content of 35% was obtained.

Production Example 7
In Production Example 1, the amount of jER1004 was changed from 90 parts to 70 parts, and 10 parts of dimer acid instead of 10 parts of dimer acid and 57 parts of the acrylic resin AC8 solution obtained in Synthesis Example 8 (20 parts in solid content) A modified epoxy resin ME7 solution having a solid content of 35% was obtained except that the combination was used.

Production Example 8
In Production Example 7, the same procedure as in Production Example 7 was performed except that the acrylic resin AC8 solution obtained in Synthesis Example 8 was changed to the polyester resin PE8 solution obtained in Synthesis Example 16, and a modified epoxy resin ME8 solution having a solid content of 35% was obtained. Got.

  Table 2 shows the blending amounts in Production Examples 1 to 8. The compounding amounts in Table 2 are all expressed by solid mass.

Production Example 9 Production of Resol Type Phenolic Resin C1 Solution In a reaction vessel, 100 parts of p-cresol, 178 parts of 37% formaldehyde aqueous solution and 1 part of sodium hydroxide were blended and reacted at 60 ° C. for 3 hours. Dehydrated at 50 ° C. for 1 hour. Then, 100 parts of n-butanol and 3 parts of phosphoric acid were added and reacted at 110 to 120 ° C. for 2 hours. After completion of the reaction, the resulting solution was filtered to remove the sodium phosphate produced, thereby obtaining a resol type phenolic resin C1 solution having a solid content of about 50%. The obtained resin had a number average molecular weight of 880, an average number of methylol groups per benzene nucleus of 0.4, and an average number of alkoxymethyl groups of 1.0.

Production Example 10 Production of paint for back side 80 parts of jER1009F (Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent of about 2000) mixed solvent 1 [cyclohexanone / ethylene glycol monobutyl ether / swazol 1500 (Maruzen Petrochemical Co., Ltd.) Manufactured high-boiling aromatic hydrocarbon solvent) = 3/1/1 (mass ratio)] in 200 parts of an epoxy resin solution dissolved in 120 parts, titanium white 40 parts, barita 40 parts and mixed solvent 2 [Swazole 1500 / A suitable amount of cyclohexanone = 1/1 (mass ratio)] was mixed, and the pigment was dispersed until the tube (particle diameter of the coarse pigment particles) became 20 microns or less. Next, 26.7 parts (20% by solid content) of Desmodur BL-3175 (manufactured by Sumika Bayer Urethane Co., Ltd., HDI isocyanurate type polyisocyanate compound solution blocked with methyl ethyl ketoxime, about 75% solid content) was added to this dispersion. Part), Takenate TK-1 (manufactured by Takeda Pharmaceutical Co., Ltd., organotin blocking agent dissociation catalyst, solid content of about 10%) is added and mixed uniformly, and the mixed solvent 2 is further added to obtain a viscosity of about 80 seconds ( Ford cup # 4/25 ° C.) to obtain a paint for the back surface.

Manufacture of anti-corrosion paint composition
Reference example 1
160 parts of modified bisphenol-type epoxy resin ME1 solution 35% solid content obtained in Production Example 1 (56 parts by solids), 20 parts vanadium pentoxide, 20 parts calcium metasilicate, 20 parts calcium phosphate, 20 parts titanium white, An appropriate amount of 20 parts of barita and mixed solvent 2 [Swazole 1500 / cyclohexanone = 1/1 (mass ratio)] was mixed, and pigment dispersion was performed until the tub (particle diameter of the coarse pigment particles) became 20 microns or less. Next, 68.6 parts of a hydroxyl group-containing acrylic resin AC1 solution having a solid content of 35% obtained in Synthesis Example 1 (24 parts by solid content) Desmodur BL-3175 (manufactured by Sumika Bayer Urethane Co., Ltd., methyl ethyl ketoxime) was added to this dispersion. HDI isocyanurate type polyisocyanate compound solution blocked with 26.7 parts (solid content of about 75%), Takenate TK-1 (manufactured by Takeda Pharmaceutical Co., Ltd., organotin blocking agent dissociation catalyst, solids) (About 10%), 2 parts were added and mixed uniformly, and the mixed solvent 2 was further added to adjust the viscosity to about 80 seconds (Ford Cup # 4/25 ° C.) to obtain a rust-preventive coating composition.

Reference Examples 2, 4-9, 19-23, 29 and 30, Examples 10 , 11 , 13-18, 24-28, 31 and 32, and Comparative Examples 2-5 and 7-10
In Reference Example 1, except that the hydroxyl group-containing film-forming resin, modified bisphenol-type epoxy resin, curing agent, adhesion-imparting agent, rust preventive pigment, and other pigments used are as shown in Table 3 below, It carried out similarly and obtained each antirust coating composition. However, in Reference Examples 8 and 9, and Examples 17 and 18, 1 part of Neicure 5225 (manufactured by King Industries, Inc., an amine neutralized solution of dodecylbenzenesulfonic acid) instead of 2 parts of Takenate TK-1. Are to be blended.

Reference example 3
114 parts of modified bisphenol-type epoxy resin ME1 solution 35% solid content obtained in Production Example 1 (40 parts in solid content) and 46 parts of hydroxyl-containing acrylic resin AC1 solution 35% solid content obtained in Synthesis Example 1 (solid content) 16 parts) in a mixed resin solution of 160 parts, 20 parts of vanadium pentoxide, 20 parts of calcium metasilicate, 20 parts of calcium phosphate, 20 parts of titanium white, 20 parts of varita, and mixed solvent 2 [Swazole 1500 / cyclohexanone = 1/1. (Mass ratio)] was mixed in an appropriate amount, and pigment dispersion was carried out until the tube (particle diameter of the coarse pigment particles) became 20 microns or less. Next, to this dispersion, 23 parts of a hydroxyl-containing acrylic resin AC1 solution having a solid content of 35% obtained in Synthesis Example 1 (8 parts in solid content), Desmodur BL-3175 (manufactured by Sumika Bayer Urethane Co., Ltd., methyl ethyl ketoxime) Blocked HDI isocyanurate type polyisocyanate compound solution, solid content of about 75%) 26.7 parts (20 parts by solid content), Takenate TK-1 (manufactured by Takeda Pharmaceutical Co., Ltd., organotin blocking agent dissociation catalyst, solid content) (About 10%) 2 parts were added and mixed uniformly, and the mixed solvent 2 was further added to adjust the viscosity to about 80 seconds (Ford Cup # 4/25 ° C.) to obtain a rust preventive coating composition.
Example 12
Reference Example 3, hydroxyl group-containing film-forming resin to be used, modified bisphenol epoxy resin, curing agent, adhesion imparting agents, anticorrosive pigment, except that the like other pigments be as shown in Table 3, and Reference Example 3 It carried out similarly and obtained the antirust coating composition.

Comparative Example 1
80 parts of jER1009F (Japan Epoxy Resin, bisphenol A type epoxy resin, epoxy equivalent of about 2000) mixed solvent 1 [cyclohexanone / ethylene glycol monobutyl ether / swazol 1500 (manufactured by Maruzen Petrochemical Co., Ltd., high boiling aromatic hydrocarbon) System solvent) = 3/1/1 (mass ratio)] was dissolved in 149 parts to obtain 229 parts of a 35% epoxy resin solution. 160 parts (56 parts by solid content) of the obtained 35% epoxy resin solution were mixed with 20 parts vanadium pentoxide, 20 parts calcium metasilicate, 20 parts calcium phosphate, 20 parts titanium white, 20 parts barita, and mixed solvent 2 An appropriate amount of [Swazole 1500 / cyclohexanone = 1/1 (mass ratio)] was mixed, and the pigment was dispersed until the tub (particle diameter of the coarse pigment particles) became 20 microns or less. Subsequently, the remaining 69 parts of the 35% epoxy resin solution (24 parts in solid amount), Desmodur BL-3175 (manufactured by Sumika Bayer Urethane Co., Ltd., HDI isocyanurate type blocked with methyl ethyl ketoxime) were added to this dispersion. 26.7 parts of polyisocyanate compound solution (solid content: about 75%) 26.7 parts (20 parts by solid content), Takenate TK-1 (manufactured by Takeda Pharmaceutical, organotin blocking agent dissociation catalyst, solid content: about 10%) In addition, the mixture was uniformly mixed, and the mixed solvent 2 was further added to adjust the viscosity to about 80 seconds (Ford Cup # 4/25 ° C.) to obtain a rust preventive coating composition.

Comparative Examples 6 and 11
In Comparative Example 1, the same procedure as in Comparative Example 1 was conducted except that the hydroxyl group-containing film-forming resin, epoxy resin, curing agent, adhesion-imparting agent, rust preventive pigment, and other pigments used were as shown in Table 3 below. Each rust preventive coating composition was obtained.

  The amount of each component in Table 3 is indicated by solid mass.

In Table 3 above, (Note) in the table has the following meanings.
(Note 1) jER 1009F: manufactured by Japan Epoxy Resin Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent of about 2000.
(Note 2) Cymel 303: Nippon Cytec Industries, Ltd., trade name, methyl etherified melamine resin.
(Note 3) Ca ion exchange silica: R. Grace & Co. SHIELDEX (Shielddex, registered trademark) C303 manufactured by the company.

Preparation of test coating plate Each of the anticorrosive coating compositions obtained in Reference Examples 1 to 9, 19 to 23, 29 and 30, Examples 10 to 18, 24 to 28, 31 and 32, and Comparative Examples 1 to 11 And using the top coating, each material was painted and baked according to the following coating specifications to obtain each test paint plate.

Paint specifications:
A galvalume steel plate subjected to chromate conversion treatment (plate thickness 0.35 mm, aluminum-zinc alloy plated steel plate, containing about 55% aluminum in the alloy, alloy plating basis weight 150 g / m ² ) was obtained in Production Example 10 above. The back coating was applied with a bar coater to a dry film thickness of 8 μm, and baked for 30 seconds so that the maximum material temperature reached 180 ° C. to form a back coating film. On the plated steel plate surface opposite to the back coating film of the coating plate on which this back coating film was formed, each rust preventive coating composition obtained in each of the above examples was applied with a bar coater so as to have a dry film thickness of 5 μm, Each primer coating film was formed by baking for 40 seconds so that the maximum material temperature reached 220 ° C. After cooling, KP color 1580B40 (trade name, polyester-based top coating, blue, glass transition temperature of cured coating about 70 ° C.) is applied to these primer coatings with a bar coater. The coating was applied to a thickness of about 15 μm, and baked for 40 seconds so that the maximum material temperature reached 220 ° C., to obtain a test plate for each test.

Coating Film Performance Test A coating film performance test was performed according to the following test method for each test coated plate obtained according to the above coating specifications. The test results are shown in Table 4 below.

Test method Folding workability: At a room temperature of 20 ° C., each test coating plate cut to a size of 6 cm × 12 cm is subjected to 4T bending processing (the surface side of the coating plate is applied so that the length of the bent portion is 6 cm). Folding was performed outside, and four plates having the same thickness as the painted plate were sandwiched inside, and the painted plate was bent 180 degrees in a vise). The crack resistance of the coating film in the bent portion and the adhesion of the coating film in the bent portion were evaluated according to the following criteria. The adhesiveness of the coating film in the bent portion was evaluated by the degree of peeling of the coated film in the bent portion when a cellophane adhesive tape was applied to the bent portion and the tape was peeled off instantaneously.
(Draft resistance of the coating film in the bent part)
◎: No cracking of the coating film is observed in the processed part ○: Slight cracking of the coating film is recognized in the processing part Δ: There is considerable cracking of the coating film in the processing part ×: Cracking of the coating film is observed in the processing part Remarkably recognized.
(Adhesion of the coating film in the bent part)
◎: No peeling of the coating film is observed in the processed area ○: A slight peeling of the coating film is observed in the processing area Δ: A considerable peeling of the coating film is observed in the processed area X: The coating film is peeled off on the entire processing area To do.

  Boiling water resistance: After each test coating plate cut to a size of 5 cm × 10 cm is immersed in boiling water at about 100 ° C. for 5 hours, it is pulled up to evaluate the appearance of the coating film on the surface side, and a cross-cut tape adhesion test And evaluated. The cross-cut tape adhesion test is based on JIS K-5400 8.5.2 (1990) cross-cut tape method, the gap interval of the cuts is 1 mm, 100 cross-cuts are made, and cellophane adhesive tape is adhered to the surface. And the number of grids remaining on the coated surface after abrupt peeling was examined.

A: There is no abnormality such as blistering or whitening in the coating film, and there are 100 remaining grids,
○: There are no abnormalities such as blistering and whitening in the coating film, and a residual grid number of 91 to 99,
Δ: Slightly abnormalities such as blistering or whitening were observed in the coating film, and the residual grid number was 91 to 99, or the coating film had no abnormality such as blistering or whitening, but the residual grid number was 71 to 99. 90 pieces
X: Generation | occurrence | production of the swelling of a coating film is recognized fairly or remarkably, or the number of remaining grids is 70 or less.

  Alkali resistance: The back surface and the cut surface of each test paint plate cut to a size of 5 cm × 10 cm were sealed with a rust-proof paint, and a cross cut reaching the substrate was put in the center of the front side of the paint plate. This coated plate was immersed in a 5% aqueous sodium hydroxide solution at 30 ° C. for 48 hours, then taken out, washed, and evaluated for the appearance of the coating on the surface side of the coated plate dried at room temperature. Was peeled off, and the peel width (one side) from the cut portion in the coating film after peeling off was evaluated.

A: There is no occurrence of swelling, and the tape peeling width from the cut part is 1.5 mm or less.
○: There is no occurrence of blisters, and the tape peeling width from the cut part exceeds 1.5 mm, 3 mm or less,
Δ: Slight occurrence of swelling is observed, but tape peeling width from the cut portion is 3 mm or less, or occurrence of swelling is not recognized, but the tape peeling width from the cut portion exceeds 3 mm,
X: Generation | occurrence | production of a swelling is recognized and the tape peeling width from a cut part exceeds 3 mm.

  Scratch resistance: At a room temperature of 20 ° C., the edge of the 10-yen coin is pressed at an angle of about 45 degrees against the coating surface on the surface side of each test coating plate, and the 10-yen copper coin is 10 mm while being pressed with a load of 3 kg. The film was evaluated according to the following criteria from the degree of scratching when the coating surface was scratched by pulling about 30 mm at a rate of / sec and the difficulty of peeling off the coating film from the substrate.

A: No metal substrate is seen on the scratched part.
○: A slight metal base is seen on the scratched part.
△: A considerable amount of metal base is seen in the scratched part,
X: A coating film is hardly left on the scratched part, and the metal base is clearly seen.

  Combined cycle corrosion test (CCT test): according to JASO M609-91 (automobile material corrosion test 1991). For each test, cut to a size of 6 cm x 12 cm so that the burrs at the edge of the long side of each test coating plate face the front side on the right side toward the front side and the back side on the left side. Insert a cross cut with a narrow angle of 30 degrees and a line width of 0.5 mm into the center of the surface side of the paint board using the back of the cutter knife, and seal the top edge of the paint board with anticorrosive paint. Is provided with a 4T bending portion (processing to bend with the surface side of the coated plate facing outward, sandwiching four plates of the same thickness as the painted plate inside, and bending the painted plate 180 degrees in a vise) With respect to the coated plate, 150 cycles (with 5% saline spraying at 35 ° C. for 2 hours) — (drying at 60 ° C. for 4 hours relative humidity 95%) — (wetting at 50 ° C. for 2 hours relative humidity 95%) as one cycle. The test was conducted for a total of 1200 hours. The state of the 4T bending process part, crosscut part, and edge part of the coated board after this test was evaluated.

(4T process part) The total length of the rust part in a 4T process part was evaluated.
A: No occurrence of rust,
○: White rust is observed, but less than 20 mm,
Δ: White rust is 20 mm or more and less than 40 mm,
X: Generation | occurrence | production of white rust 40 mm or more or red rust is recognized.

(Cross cut part) Corrosion state of the cross cut part, by the average value of the white rust occurrence length ratio in the bare metal exposed part of 0.5mm cut width, and the left and right swelling width (sum of both sides) of the cut part, Evaluation was made according to the following criteria.
A: White rust generation length ratio in exposed metal portion is less than 50% and swelling width is less than 3 mm,
○: The white rust generation length ratio in the bare metal exposed portion is 50% or more and less than 3 mm, or the white rust occurrence length ratio in the bare metal exposed portion is less than 50% and the swelling width is 3 mm or more and less than 5 mm,
Δ: White rust generation length ratio in exposed metal portion is 50% or more and swelling width is 5 mm or more and less than 10 mm,
X: The white rust generation length ratio in the bare metal exposed part is 50% or more and the swelling width is 10 mm or more.

(Edge part) The average value of the edge creep widths of the left and right long sides of the coated plate was determined and evaluated according to the following criteria.
A: Less than 5 mm
○: 5 mm or more and less than 10 mm,
Δ: 10 mm or more and less than 20 mm,
X: 20 mm or more.

  Weather-resistant salt spray test: Based on A method of accelerated weathering (xenon lamp method) test for long-term durability of coating film specified in JIS K 5600 7.7 on a test coating plate cut to a size of 5 cm × 10 cm, Irradiation was continued for 500 hours with a xenon weatherometer under repeated cycle conditions (wet 18 minutes-dry 102 minutes). Next, the back surface and the cut surface were sealed with a rust preventive paint, and a cross cut reaching the substrate was put in the center of the surface of the painted plate. About this coating board, after performing the salt spray test (JIS Z-2371) for 500 hours, the external appearance of the plane part was evaluated by the following reference | standard.

A: The swelling / rust progression width from the cut part is 3 mm or less on average across the cut, and no other abnormalities are observed.
○: The bulge / rust progression width from the cut part exceeds 3 mm and is 5 mm or less, and no abnormality is observed in the flat part or the like, or slight blistering is observed in the flat part, but from the cut part The swelling / rust progression width is 3 mm or less.
Δ: The swelling / rust progression width from the cut part exceeds 3 mm and is 5 mm or less, and slight swelling is observed in the flat part.
X: The swelling / rust progression width from the cut portion exceeds 5 mm, or significant swelling is observed in the flat portion.

Claims (6)

(A) A hydroxyl group-containing film-forming resin which is a polyester resin having a glass transition temperature of -20 to 50 ° C. and a hydroxyl value of 20 to 100 mg KOH / g and a number average molecular weight of 2,000 to 30,000, (B) a resin obtained by reacting a soft organic component and a bisphenol type epoxy resin, and based on the total 100 parts by weight of both the soft organic component and a bisphenol type epoxy resin, a soft organic components 1 to 50 parts by weight of bisphenol type A coating composition comprising a bisphenol-type epoxy resin modified with a soft organic component, (C) a curing agent, and (D) a non-chromium rust preventive pigment, which is obtained by reacting 99 to 50 parts by mass of an epoxy resin. , the resin (a), based on the total 100 parts by weight of the solid content of the resin (B) and curing agent (C), the resin (a) is 5 to 90 parts by weight, the resin B) 5 to 90 parts by weight, the curing agent (C) is in the range of 5 to 45 parts by weight, and a soft organic component in the resin (B) is an aliphatic polybasic acid having 4 to 36 carbon atoms, An acrylic resin having a glass transition temperature of -20 to 50 ° C and an acid value of 5 to 40 mgKOH / g having a carboxyl group as a reactive group that reacts with an epoxy group, and a glass transition temperature of -20 to 50 ° C and an epoxy group A rust preventive coating composition containing no chromium-based rust preventive pigment, which is at least one of polyester resins having a carboxyl group as a reactive group and having an acid value of 5 to 70 mgKOH / g.
Anticorrosive coating composition of claim 1 wherein the aliphatic polybasic acid having 4 to 36 carbon atoms is a dimer acid. The rust preventive coating composition according to claim 1 or 2, wherein the curing agent (C) is at least one crosslinking agent among an amino resin , a phenol resin, and a polyisocyanate compound which may be blocked. The rust preventive pigment (D) contains (1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate, and (2) at least one silicon of metal silicate and silica fine particles. The rust preventive coating composition according to any one of claims 1 to 3 , comprising a compound and (3) a phosphoric acid metal salt. A cured coating film based on the coating composition according to any one of claims 1 to 4 is formed on one or both surfaces of a metal plate which may be subjected to chemical conversion treatment on the surface. Painted metal plate. A cured coating film based on the coating composition according to any one of claims 1 to 4 is formed on one surface or both surfaces of a metal plate, the surface of which may be subjected to chemical conversion treatment. A coated metal plate having a multilayer coating film formed by forming a top coating film on at least one surface.