JP2008050454A - Water-based coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based coating composition having excellent coating stability, especially coating stability, finished state and long-term corrosion resistance in the continuous use of the coating. <P>SOLUTION: The water-based coating composition contains (A) a cationic epoxy resin, (B) a crosslinking agent, (C) a dispersion resin containing phosphate group, (D) zinc powder, (E) an electrically conductive filler and (F) a triazole compound. The amount of the dispersion resin (C) containing phosphate group is 0.1-30 pts.mass, the zinc powder (D) is 5-200 pts.mass, the conductive filler (E) is 0.1-100 pts.mass and the triazole compound (F) is 0.1-30 pts.mass based on 100 pts.mass of the sum of the solid components of the cationic epoxy resin (A) and the crosslinking agent (B). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aqueous coating composition that is excellent in coating stability, particularly coating stability during continuous use of paint, finishing performance, and long-term corrosion resistance.

  Conventionally, paints generally containing a large amount of zinc powder can obtain a coating film having excellent anticorrosion properties by utilizing the sacrificial anticorrosive effect of zinc.

  However, because it is a paint using organic solvents, there is always a danger of fire, and there are concerns about the impact on the health of the user and the impact on the environment. Low VOC regulations (volatile organic compounds, Volatile Organic Compounds) HAPs (Hazardous Air Pollutants) regulations restrict its use. From such a background, water-based coatings are required.

  However, conventionally, when a large amount of zinc dust is blended for the purpose of obtaining a highly anticorrosive coating film in water-based paints, there is a problem in paint stability such as adhesion of paint agglomerates to the draft section of the paint tank or clogging of the filter. May occur or the finish may be reduced. On the other hand, when the blending amount of zinc powder is reduced in order to ensure the stability of the paint, especially the paint stability and finish when the paint is continuously used, the anticorrosion property is insufficient.

  Conventionally, the black zinc dust coating composition formed by mix | blending 50-86 mass parts of zinc powder and 1-10 mass parts of conductive carbon black with respect to 100 mass parts of resin components is disclosed (patent document 1). The above-mentioned Patent Document 1 relates to a coating material using an organic solvent as a solvent, and methyl ethyl ketone and xylene are used in a large amount in the examples, and are not compatible with the regulation of volatile organic compounds.

  In addition, an invention relating to a rust preventive coating composition comprising a silicon-based inorganic binder, zinc dust and a lubricant as main components is disclosed (Patent Document 2). The invention of the above-mentioned Patent Document 2 is based on the premise that an organic solvent is used as a solvent, and is not related to an aqueous paint for the purpose of reducing volatile organic compounds, but about applying a large amount of zinc to an aqueous paint. There is no description of measures.

  Also disclosed is a zinc dust-containing aqueous composition containing at least one phosphate ester resin selected from the group consisting of zinc dust and a phosphate ester of an epoxy resin and a phosphate ester of a hydroxyl group-containing resin (patent) Reference 3). In Patent Document 3, although it is a highly anticorrosive coating film containing a large amount of zinc powder in the coating film, the finish and paint stability are impaired.

In addition, an invention relating to an electrodeposition coating containing 1 to 100 parts by mass of zinc powder dispersed with a phosphate group-containing dispersing resin with respect to a total solid content of 100 parts by mass of the base resin and the curing agent of the electrodeposition coating is disclosed. (Patent Document 4). Patent Document 4 is an invention in which zinc powder is applied to an electrodeposition paint that is a water-based paint. However, the anticorrosion property is insufficient, and in order to obtain a high anticorrosion property, it is necessary to blend a larger amount of zinc powder. Therefore, paint stability and finish are greatly impaired.

  Also obtained by coating the composition with a resin binder, a curing agent, and a conductive pigment such as zinc, which is a reaction product of an epoxy-containing polymer and a compound containing a phosphorus-containing acid group. An invention relating to a composition in which the coating film has good anticorrosion properties and has a characteristic of being weldable onto the coating film is disclosed (Patent Document 5). The conductive pigment such as zinc described in Patent Document 5 is also effective in improving the anticorrosion property, but when a large amount of conductive pigment such as zinc is used in the aqueous coating, the stability and finish of the coating are impaired.

  Moreover, triazole compound 0.3-15 with respect to a total of 100 weight part of at least 1 sort (s) of aqueous resin chosen from aqueous | water-based alkyd resin and aqueous | water-based epoxy ester resin, and 5-50 weight part of aqueous | water-based melamine resin. An aqueous coating composition characterized by containing 5 to 50 parts by weight of an anticorrosive pigment of phosphate or phosphite modified with parts by weight and a calcium compound is disclosed (Patent Document) 6). The water-based coating composition of Patent Document 6 uses a triazole compound for the corrosion resistance and water resistance improvement of the edge part which is a general part and an end face in an aluminum steel plate and an aluminum alloy plated steel plate, but the corrosion resistance is insufficient, and further There was a need for improvement.

  In addition, a zinc-dispersed paste obtained by dispersing zinc and a conductive filler using a phosphoric acid group-containing dispersing resin, a base resin and a water-based paint containing a crosslinking agent, the total solid content of the base resin and the crosslinking agent An aqueous coating material is disclosed in which zinc is blended in an amount of 10 to 500 parts by mass and a conductive filler in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass (Patent Document 7). When the paint described in Patent Document 7 is used continuously in a continuous facility such as a painting line and mechanical share such as paint agitation, circulation and filtration is added, the paint agglomerates are formed in the paint tank. There are problems such as adhering to the drafting section and clogging the filtration equipment, and in the obtained coated articles, there are problems such as occurrence of fuzz and a noticeable decrease in finish such as chili skin. .

  In the above Patent Documents 1 to 7, there is a problem in at least one of coating stability, particularly stability at the time of continuous use of the coating material, finishing performance, and long-term corrosion resistance.

JP-A-6-49393 JP-A-8-73777 JP 11-124520 A JP 2004-51686 A JP 2004-529223 A JP 2002-121469 A JP 2006-143809 A

  The problem to be solved is to provide an aqueous coating composition that is excellent in coating stability, particularly coating stability during continuous use of the coating, finish, and long-term corrosion resistance.

  As a result of intensive studies to solve the above problems, the present inventors have found that a phosphate group-containing dispersion resin, zinc powder, conductive filler, triazole compound, and optionally, calcium ion-exchanged amorphous silica By the aqueous coating composition containing fine particles, a coating film having excellent coating stability, particularly coating stability at the time of continuous use of the coating material, finishing performance and long-term corrosion resistance has been found, and the present invention has been completed.

  The aqueous coating composition of the present invention can reduce volatile organic compounds (lower VOC) and is excellent in coating stability, particularly coating stability during continuous use of the coating. Furthermore, a metal member having excellent finish and long-term corrosion resistance can be obtained.

  The aqueous coating composition of the present invention can control the elution amount of zinc in the coating film by adding a triazole compound (so-called sustained release property is imparted to the coating film), so that the anticorrosion effect is maintained over a long period of time. In particular, a coating film excellent in exposure corrosion resistance can be obtained. Furthermore, by containing amorphous silica fine particles exchanged with zinc and calcium ions in the coating film, it is possible to further improve the corrosion resistance.

  The reason why the above effects can be obtained is that the elution amount of zinc can be controlled by blending the triazole compound, so even if the blending amount of zinc is reduced compared to the conventional, the corrosion resistance is equal or better. it can. Since the blending amount of zinc can be reduced as compared with the prior art, the stability of the paint can be improved. Furthermore, since the blending amount of zinc can be reduced as compared with the conventional case, a coated article having excellent finish can be obtained.

  The present invention provides a cationic epoxy resin (A), a crosslinking agent (B), a phosphate group-containing dispersion resin (C), a zinc powder (D), a conductive filler (E), a triazole compound (F), Accordingly, it is an aqueous coating composition containing amorphous silica fine particles (G) subjected to calcium ion exchange. Details will be described below.

Cationic epoxy resin (A):
The cationic epoxy resin (A) used in the aqueous coating composition of the present invention is a resin obtained by adding a cationic group-containing compound to an epoxy resin.

As the epoxy resin, an epoxy resin obtained by a reaction between a polyphenol compound and an epihalohydrin such as epichlorohydrin is preferable.
Examples of polyphenol compounds that can be used for forming the epoxy resin include bis (4-hydroxyphenyl) -2,2-propane (bisphenol A), 4,4-dihydroxybenzophenone, and 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 novolak, cresol novolak, etc. Can do.
Moreover, as an epoxy resin obtained by reaction of a polyphenol compound and epichlorohydrin, the following formula induced | guided | derived from bisphenol A is mentioned especially,

(Here, n = 0 to 8 are preferred.)

  The epoxy resin is generally from 180 to 2,500, preferably from 200 to 2,000, more preferably having an epoxy equivalent weight in the range from 400 to 1,500, and is generally at least 200, in particular from 400 to Those having a number average molecular weight in the range of 4,000, more particularly 800 to 2,500 are suitable.

  Examples of such commercially available epoxy resins include those sold by Japan Epoxy Resins Co., Ltd. under the trade names of Epicoat 828EL, 1002 on the left, 1004 on the left, and 1007 on the left.

  The epoxy resin may be plasticized and modified, and the plasticizing modifier is preferably compatible with the epoxy resin and hydrophobic. The amount of plastic modification is preferably 3 to 200 parts by mass, and more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the epoxy resin.

  The cationic group-containing compound is a cationic group-containing compound for introducing a cationic group into the epoxy resin to make it water-dispersed or water-soluble. Examples of the amino group-containing compound as the cationic group-containing compound include di-alkylamines such as dimethylamine, diethylamine, diisopropylamine, and dibutylamine; diethanolamine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylamino Alkanolamines such as ethanol; alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, triethylenetetramine, and ketiminates of these polyamines; ethyleneimine , Alkyleneimines such as propyleneimine; cyclic amines such as piperazine, morpholine and pyrazine And the like.

  Examples of the onium base-containing compound as the cationic group-containing compound include an ammonium base, a sulfonium base, and a phosphonium base, which are obtained by reacting an epoxy group with a monocarboxylic acid such as a tertiary amine or secondary sulfide. . In the present invention, it is preferable to use an onium base-containing compound in terms of anticorrosion and paint stability.

  In the production of the cationic epoxy resin (A), the blending ratio of the cationic group-containing compound such as amino group-containing compound or onium base-containing compound to the epoxy resin is not strictly limited, and is suitable for use in water-based paints. Depending on the total solid content of the epoxy resin and the cationic group-containing compound, the epoxy resin is 60 to 95% by mass, preferably 65 to 90% by mass, and the cationic group-containing compound is 5%. The range of -40 mass%, preferably 10-35 mass% is good.

  The above addition reaction can be usually performed in a suitable solvent at a temperature of about 80 to about 170 ° C., preferably about 90 to about 150 ° C. for about 1 to 6 hours, preferably about 1 to 5 hours. Examples of the solvent include hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Examples include amide systems such as dimethylformamide and dimethylacetamide; alcohol systems such as methanol, ethanol, n-propanol, and iso-propanol; or a mixture thereof.

Crosslinking agent (B):
As the crosslinking agent (B) in the cationic epoxy resin (A), a blocked polyisocyanate compound, a melamine resin, or the like is used. In the water-based coating composition of the present invention, the blocked polyisocyanate compound, which is an addition reaction product in a substantially stoichiometric amount of the polyisocyanate compound and the blocking agent, is used for the curability and corrosion resistance of the coating film. From the viewpoint of

  The blocked polyisocyanate compound is obtained by blocking an isocyanate group of a polyisocyanate having two or more free isocyanate groups in one molecule with a blocking agent. As the polyisocyanate compound, conventionally known compounds can be used. For example, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate. (Usually referred to as “MDI”), crude MDI, bis (isocyanate methyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate, and the like; Cyclic polymer of cyanate compound, isocyanate biuret; ethylene glycol, propylene in excess of these polyisocyanate compounds Recall, may be mentioned trimethylolpropane, hexanetriol, terminal isocyanate-containing compounds obtained by reacting a low molecular weight active hydrogen-containing compounds such as castor oil and the like. These can be used alone or in combination of two or more.

The blocking agent blocks a free isocyanate group, and can easily react with a hydroxyl group when heated to, for example, 100 ° C. or higher, preferably 130 ° C. or higher.
Examples of the blocking agent include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and hydroxybenzoic acid methyl; ε-caprolactam, δ-valerolactam, γ -Lactams such as butyrolactam and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether , Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, pro Ether systems such as lenglycol monomethyl ether and methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid esters such as methyl glycolate, ethyl glycolate and butyl glycolate; lactic acid esters such as lactic acid, methyl lactate, ethyl lactate and butyl lactate; Alcohols such as methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime System: Activity of dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, etc. Methylene series; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol and other mercaptans; Acid amides such as acetic acid amide, stearic acid amide and benzamide; imides such as succinimide, phthalic acid imide and maleic acid imide; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, Amines such as butylamine, dibutylamine and butylphenylamine; imidazoles such as imidazole and 2-ethylimidazole Ureas such as urea, thiourea, ethyleneurea, ethylenethiourea, diphenylurea; carbamate esters such as phenyl N-phenylcarbamate; imines such as ethyleneimine and propyleneimine; sodium bisulfite, potassium bisulfite, etc. A sulfite system etc. are mentioned.

  Other examples include pyrazoles such as 3,5-dimethylpyrazole, 3-methylpyrazole, 4-nitro-3,5-dimethylpyrazole and 4-bromo-3,5-dimethylpyrazole. Among these, a preferable blocking agent is 3,5-dimethylpyrazole.

  The melamine resin is a melamine resin in which 3 or more methylol groups are averaged as a methyl ether per triazine nucleus, or a melamine resin in which a part of the methoxy group is substituted with a monoalcohol having 2 or more carbon atoms, A hydrophilic melamine having an imino group can be suitably used.

  Examples of the methylolated amino resin include methylolated amino resins obtained by a reaction between melamine and an aldehyde. Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Moreover, what methylated the methylol group of this methylolated amino resin partially or entirely with monoalcohol can also be used. Examples of monoalcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

  As commercial products, for example, melamine resin satisfying such conditions is Cymel 202, Cymel 232, Cymel 235, 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. , 2028, 2061 (above, manufactured by Mitsui Chemicals, Inc.).

  In the aqueous coating composition of the present invention, the blending ratio of the crosslinking agent (B) to the cationic epoxy resin (A) is based on a total solid content of 100 parts by mass of the cationic epoxy resin (A) and the crosslinking agent (B). Cationic epoxy resin (A) / crosslinking agent (B) = 95/5 (parts by mass) to 50/50 (parts by mass), preferably cationic epoxy resin (A) / crosslinking agent (B) = 90 / 10 (parts by mass) to 55/45 (parts by mass), more preferably cationic epoxy resin (A) / crosslinking agent (B) = 88/12 (parts by mass) to 60/40 (parts by mass). However, it is good for improving the stability of the paint, particularly when the paint is continuously used.

Phosphate group-containing dispersion resin (C):
The phosphoric acid group-containing dispersion resin (C) is represented by -OPO (OR) (OH) .. Formula (1)
(In Formula (1), R is a hydrogen atom or a C4-C10 hydrocarbon group) The resin containing the phosphoric acid group shown.
This phosphoric acid group-containing dispersion resin (C) preferably contains a cationic group such as a quaternary ammonium base or a tertiary sulfonium base.
The phosphoric acid group-containing dispersion resin (C) is, for example, a copolymerization with a polymerizable monomer containing a phosphoric acid group represented by -OPO (OR) (OH) and other polymerizable monomers. Obtained by reaction.

Phosphoric acid group-containing polymerizable monomer is represented by -OPO (OR) (OH) .. Formula (1) in one molecule.
(Wherein R is a hydrogen atom or a hydrocarbon group having 4 to 10 carbon atoms) each having a phosphate group and one or more polymerizable double bonds, such as monobutyl phosphate Glycidyl groups such as glycidyl acrylate and glycidyl methacrylate are added to one acidic hydroxyl group contained in phosphate such as (HO) ₂ PO (OC ₄ H ₉ ) and monoisodecyl phosphate (HO) ₂ PO (OC ₁₀ H ₂₁ ). It can be obtained by reacting the containing polymerizable monomer.

  Examples of the phosphoric acid group-containing polymerizable monomer include (2-acryloyloxyethyl) acid phosphate, (2-methacryloyloxyethyl) acid phosphate, (2-acryloyloxypropyl) acid phosphate, and (2-methacryloyloxypropyl) acid. Phosphate can also be used.

  Other polymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylic. Acrylic ester monomers such as esterified products of (meth) acrylic acid such as lauryl acid and monoalcohol having 1 to 24 carbon atoms; (meth) acrylic such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate Hydroxyl group-containing monomers such as monoesterified products of acids and glycols having 2 to 10 carbon atoms; Onium base-containing monomers such as a reaction product of glycidyl (meth) acrylate and tertiary amine or secondary sulfide and monocarboxylic acid; styrene , Α-methylstyrene, (meth) acrylonitrile, vinyltoluene, vinyl acetate , Etc. are exemplified.

  In the presence of a polymerization initiator, the phosphoric acid group-containing dispersion resin (C) is prepared by subjecting the above polymerizable monomer containing a phosphoric acid group and other polymerizable monomers to a known method such as solution polymerization. Can be prepared by polymerization.

  The composition ratio of these polymerizable monomers in the polymerization reaction can be arbitrarily selected according to the purpose and is not particularly limited, but for example, based on the total amount of the phosphoric acid group-containing polymerizable monomer and other monomers. The phosphate group-containing polymerizable monomer is in the range of 1 to 30% by mass, preferably 5 to 20% by mass, and the other polymerizable monomer is in the range of 70 to 99% by mass, preferably 80 to 95% by mass. Is suitable.

  The number average molecular weight (Note 1) of the phosphate group-containing dispersion resin (C) is in the range of 3,000 to 100,000, preferably 5,000 to 50,000, particularly preferably 5,000 to 30,000. The acid value based on the phosphate group is 20 to 140 mgKOH / g, particularly 40 to 120 mgKOH / g, the acid value based on the carboxyl group is 100 mgKOH / g or less, the hydroxyl value is 120 mgKOH / g or less, particularly 15 to 100 mgKOH / g. The range of g is suitable for each.

(Note 1) Number average molecular weight: Measured according to JIS K 0124-83, using TSK GEL4000H _XL + G3000H _XL + G2500H _XL + G2000H _XL (manufactured by Tosoh Corporation) as a separation column at a flow rate of 1.0 ml / min. Then, using GPC tetrahydrofuran as an eluent, it was obtained by calculation from a chromatogram obtained with an RI refractometer and a standard polystyrene calibration curve.

  Other examples of the phosphoric acid group-containing dispersion resin (C) include reaction products of epoxy resins with monobutyl phosphate and orthophosphoric acid, reaction products of glycidyl group-containing acrylic resins with monobutyl phosphate and orthophosphoric acid, styrene and A reaction product of a polymer with allyl alcohol and orthophosphoric acid, polycaprolactone phosphate, and the like can also be used. By reacting the epoxy resin with monobutyl phosphate or orthophosphoric acid, a phosphoric acid group-containing epoxy resin is obtained.

  As an epoxy resin used as a starting material, an epoxy resin obtained by a reaction between a polyphenol compound and epichlorohydrin is preferable from the viewpoint of anticorrosiveness of the coating film. The number average molecular weight of the epoxy resin is preferably 1,000 to 10,000, more preferably 2,000 to 5,000. Examples of such commercially available epoxy resins include those sold by Japan Epoxy Resins Co., Ltd. under the trade names of Epicoat 828EL, 1002 on the left, 1004 on the left, and 1007 on the left. The epoxy resin may be used as it is, but of course, a plasticized and modified epoxy resin may be used.

Zinc powder (D):
Specifically, zinc powder (D) can be zinc powder, zinc powder (JIS K 8031), zinc powder, zinc dust, etc., and surface treatment (for example, silica treatment, phosphoric acid treatment, chromic acid treatment, fatty acid) Treatment, polymer treatment) may be performed. As commercially available products, zinc powder MCS, zinc powder #F (above, manufactured by Sakai Chemical Industry Co., Ltd.), zinc powder LS-2, zinc powder LS-5, zinc powder LS-30 (above, manufactured by Mitsui Chemicals Co., Ltd.) are available. Can be mentioned.

Conductive filler (E):
Examples of the conductive filler (E) include carbon powders such as carbon black, graphite, fullerene, and carbon nanotubes, metal powders such as nickel and silver, metal oxide powders such as nickel oxide and titanium oxide, zirconium silicide, and titanium silicide. Metal nitrides such as metal silicides, zirconium nitrides, titanium nitrides, borides such as zirconium borides, titanium borides, tungsten borides, zirconium carbides, titanium carbides (average particle size 1-10 μm), tungsten carbides (average particle size) 1-10 μm) and the like, and powders of alkali metals such as potassium titanate.

  Specific examples of the carbon-based powder include Ketjen Black EC, Ketjen Black EC600JD (trade name, Ketjen Black, manufactured by Lion Corporation), Vulcan XC-72, Vulcan XC-605 (above, Cabot Corporation). Manufactured, trade name, furnace black), RP series and AGB series (above, trade name, graphite, manufactured by Ito Graphite Industries Co., Ltd.), graphite powder SP-10, SP-20, HAG-15, HAG-150, HAG-300 (Nippon Graphite, trade name, graphite), artificial graphite POG-2, POG-10, POG-20 (above, Sumitomo Chemical Co., trade name, graphite) and the like.

  Other than carbon-based powders, DENTOR BK-400 (trade name, potassium titanate, conductive whisker manufactured by Otsuka Chemical Co., Ltd.), ET-500W (spherical titanium oxide surface coated with tin oxide and antimony layer), ET-600W (Tinned titanium oxide surface is coated with tin oxide and antimony layer), ET-300W (Spherical titanium oxide surface is coated with tin oxide and antimony layer), FT-1000 (Acicular titanium oxide surface is coated with tin oxide and antimony layer) ), FT-2000 (acicular titanium oxide surface is coated with tin oxide and antimony layer), FT-3000 (acicular titanium oxide surface is coated with tin oxide and antimony layer), (above, manufactured by Ishihara Sangyo Co., Ltd., trade name) ), Nanotech Aluminum Oxide, Nanotech Zinc Oxide, Nanotech Cerium Oxide, Nanotech Titanium Oxide (trade name, manufactured by CI Kasei Co., Ltd.), Nikke Fine powder type 110, nickel fine powder type 210, nickel fine powder type 210H, filamentary nickel powder type 255, filamentary nickel powder type 287, nickel-coated carbon fiber, nickel-coated graphite (above, manufactured by Inco Limited, trade name) ), Albrid AG035FN (silver-coated frame-shaped powder), Albrid AG016SN (silver-coated spherical powder), Nickel flake NI-100, Nickel flake NI-A, Nickel flake NI-400, Kappa flake (above, manufactured by Toyo Aluminum Co., Ltd.) , Trade name), 23-K (trade name, conductive zinc oxide, manufactured by Hakusui Tec Co., Ltd.) and the like.

  As an effect of the conductive filler (E), the zinc dust (D) in the coating film is conducted to enhance the anticorrosive effect of the zinc powder (D) and contribute to the inhibition of corrosion at the interface between the material and the coating film. From this, the compounding quantity of the zinc dust (D) mix | blended with a water-based coating composition can be reduced, and it contributes to the improvement of coating-material stability and finish.

Triazole compound (F):
In the water-based coating composition of the present invention, by adding the triazole compound (F), the activity of zinc dust (D) is suppressed to contribute to the improvement of the coating stability. The elution amount of zinc in the film can be controlled (so-called sustained release can be imparted).

  Examples of such triazole compound (F) include 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, and 3-mercapto-1. , 2,4-triazole, 5-amino-3-mercapto-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole, 6-methyl-8-hydroxytriazolopyridazine, 6-phenyl-8 -Hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine and the like. Of these, 3-amino-1,2,4-triazole is preferred from the viewpoints of anticorrosion, paint stability, finish, and long-term anticorrosion.

  The effect of the triazole compound (F) is represented in the aqueous coating composition by suppressing the elution amount of zinc in the aqueous coating composition. Even if mechanical shear such as stirring, circulation and filtration is added, the triazole The aqueous coating composition containing the compound (F) does not aggregate and block the filter. In the obtained coating film, the elution amount of zinc is controlled (so-called coating film is provided with sustained release), and a coating film having excellent corrosion resistance over a long period of time can be obtained. In particular, the coating film has excellent exposure corrosion resistance.

  In the aqueous coating composition of the present invention, the blending amount of zinc powder (D) in the coating is zinc powder (D) with respect to 100 parts by mass of the total solid content of the cationic epoxy resin (A) and the crosslinking agent (B). 5 to 200 parts by mass, preferably 20 to 200 parts by mass, and more preferably 50 to 180 parts by mass.

  The blending amount of the conductive filler (E) is 0.1 to 100 parts by mass of the conductive filler (E), preferably 100 parts by mass of the solid content of the base resin (A) and the crosslinking agent (B), preferably 1-70 mass parts, More preferably, 5-50 mass parts is good. The blending amount of the triazole compound (F) is 0.1 to 30 parts by mass, preferably 1 to 25 parts by mass, more preferably 100 parts by mass of the solid content of the base resin (A) and the crosslinking agent (B). Is preferably 2 to 20 parts by mass.

  Furthermore, it has been found that the triazole compound (F) is more excellent in paint stability when added from a pigment dispersion paste than when blended in an emulsion formed by water dispersion together with a base resin and a curing agent.

The blending amount of the phosphoric acid group-containing dispersion resin (C) is such that the phosphoric acid group-containing dispersion resin (C) is 0. 1-30 mass parts, Preferably it is 1-20 mass parts, More preferably, 2-10 mass parts is good.
The blending amount of the zinc powder (D), the conductive filler (E) and the triazole compound (F) is within the above range, and is excellent in paint stability, particularly paint stability during continuous use of paint, It is preferable for obtaining a coating film excellent in long-term corrosion resistance.

Calcium ion exchanged amorphous silica fine particles (G):
The anion electrodeposition coating composition of the present invention is a calcium ion-exchanged amorphous silica fine particle (G) (hereinafter sometimes abbreviated as “ion-exchanged silica (G)”) for the purpose of improving corrosion resistance. Can be contained. The ion exchange silica (G) is a silica fine particle in which calcium ions are introduced into a fine porous silica carrier by ion exchange.

In addition, the ion exchange silica (G) blended in the coating film performs ion exchange with hydrogen ions that have permeated the coating film, and as a result, calcium ions Ca ²⁺ are released to protect the metal surface. Conceivable. In an aqueous coating composition, by using zinc dust (D) and ion exchange silica (G) in combination, it is possible to maintain high anticorrosion properties even if the blending amount of zinc dust (D) is reduced, and the paint stability This contributes to the improvement of performance and finish.

  Examples of commercially available ion-exchange silica include Shieldex C303 (manufactured by Fuji Devison), SHIELDEX AC-3, SHIELDEX AC-5 (all of which are manufactured by WR Grace & Co.). it can.

  In this invention, the compounding quantity of ion exchange silica (G) is 1-200 mass parts with respect to a total of 100 mass parts of base resin (A) and a crosslinking agent (B), Preferably 3-150 mass parts, More preferably, it exists in the range of 5-100 mass parts.

  The blending amount of the ion-exchanged silica (G) is within the above range to obtain a coating film having excellent coating stability, particularly coating stability at the time of continuous use of the coating, and excellent finish and long-term corrosion resistance. Therefore, it is preferable.

[Production of water-based paint composition]
The water-based coating composition of the present invention can be produced by (1). "Emulsion" obtained by adding water and dispersing cationic epoxy resin (A), cross-linking agent (B), triazole compound (F) and neutralizing agent (Note 2) and water, and phosphoric acid group-containing dispersion Using resin (C), add zinc dust (D) and conductive filler (E), ion-exchange silica (G) or other pigment (Note 3), curing catalyst, surfactant, etc. The mixture is then dispersed in a ball mill, a sand mill, etc., and zinc powder (D), conductive filler (E), ion-exchanged silica (G) and other pigments as appropriate have a particle size of 0.1 to 15 μm, preferably Is blended with “pigment dispersion paste” obtained by dispersing in 0.5 to 10 μm, diluted with deionized water, and the solid content is 5 to 35% by mass, preferably 8 to 30% by mass, more preferably Method for obtaining a 10-25% by weight aqueous coating composition ;

  (2). Using an "emulsion" obtained by adding a cationic epoxy resin (A), a crosslinking agent (B), a neutralizing agent (Note 2) and water and dispersing in water, and a phosphate group-containing dispersion resin (C) Add zinc powder (D), conductive filler (E), triazole compound (F), ion exchange silica (G) and other pigments (Note 3), curing catalyst, surfactant, etc. Next, add the remaining zinc powder (D), conductive filler (E), triazole compound (F), ion-exchange silica (G) and other pigments as appropriate, and disperse with a ball mill, sand mill, etc. A “pigment dispersion paste” having a particle size of 0.1 to 15 μm, preferably 0.5 to 10 μm, and diluted with deionized water to have a solid content of 5 to 35% by mass, preferably 8 to 30% by weight, more preferably 10-25% % Of obtaining a water-based coating composition.

  (Note 2) Neutralizing agent: An organic acid such as acetic acid, formic acid or lactic acid is used.

  (Note 3) Other pigments: For example, colored pigments such as titanium oxide, carbon black and bengara; rust preventive pigments such as aluminum phosphomolybdate, aluminum tripolyphosphate, bismuth oxide hydrate and antimony oxide; clay, mica, barita And extender pigments such as calcium carbonate and silica.

[Coating of water-based paint composition]
The aqueous coating composition can be applied by a conventionally known method, for example, brush coating, spray coating, electrostatic coating, electrodeposition coating, etc., and these may be combined arbitrarily.

For example, electrostatic coating is performed at a coating booth temperature of 15 to 40 ° C. and a coating booth humidity of 60 to 90% by using an electrostatic coating machine (for example, ABB cartridge Metabell) and a bell rotation speed of 20,000 to The coating is performed in the range of 40,000 rpm, preferably in the range of 25,000 to 35,000 rpm, and in the range of the discharge rate of 200 to 400 ml / min (specifically, the horizontal portion 250 to 350 ml / min, the vertical portion 300 to 400 ml / min). The applied voltage during electrostatic coating is preferably in the range of −90 kV to −60 kV, and the discharge pressure (SA) is preferably in the range of 1.0 to 2.0 kg / cm ² .
The film thickness is 3 to 100 μm, particularly 5 to 60 μm, as a cured coating film, and the coating film is crosslinked and cured by heating at 100 to 200 ° C., particularly 130 to 180 ° C. for 10 to 50 minutes. Can do.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited thereby. “Parts” and “%” indicate “parts by mass” and “% by mass”.

Production Example 1 Pigment Dispersion Resin Solution No. Production of 1 700 parts of bisphenol-type epoxy resin having an epoxy equivalent of about 700 was dissolved in 993 parts of ethylene glycol monobutyl ether at 90 ° C., 110 parts of nonylphenol, 61 parts of thiodiethylene glycol and 45 parts of lactic acid were added, and the acid value was 2 mg KOH at 90 ° C. The mixture was allowed to react to 70 ° C./g or lower, cooled to 70 ° C., added with 77 parts of monobutyl phosphate and aged at the same temperature for 1 hour. 1 was obtained. Resin for dispersion No. The acid value due to 1 phosphoric acid group was 56.5 mgKOH / g.

Production Example 2 Pigment Dispersion Paste No. Production of pigment dispersion resin No. 1 obtained in Production Example 1 1 part 10 (solid content 5 parts), titanium white 15
Parts, zinc powder # 3 (note 4) 100 parts, ketjen black EC (note 7) 10 parts, 3-amino-1,2,4-triazole 5 parts, shielddex C303 (note 10) 3 parts, dibutyl 1 part of tin oxide and 137 parts of deionized water were blended and dispersed in a ball mill for 20 hours to obtain pigment dispersion paste No. 50 having a solid content of 50%. 1 was obtained.

Production Examples 3 to 12 Pigment dispersion paste No. 2-No. 10 Production of Pigment Dispersion Paste No. 10 was conducted in the same manner as in Production Example 3 except that the contents of Table 1 were used. 2-No. 10 blending contents are shown.

(Note 4) Zinc powder # 3: Sakai Chemical Co., Ltd., trade name, zinc powder (Note 5) Zinc powder LS-30: Mitsui Kinzoku Chemical Co., Ltd., trade name, zinc powder,
(Note 6) Zinc powder MCS: Mitsui Kinzoku Chemical Co., Ltd., trade name, zinc powder (Note 7) Ketjen Black EC: Lion Corporation, trade name, Ketjen Black (* 8) ET-500W: Ishihara Sangyo Product name, spherical titanium oxide surface coated with tin oxide and antimony layer (Note 9) 23-K: Product name, conductive zinc oxide (Note 10) Shieldex C303: Fuji Silysia Chemical Co., Ltd. Made by company, trade name, calcium ion exchanged amorphous silica fine particles.

Production Example 13 Base resin No. 1 In a reaction vessel, Epicoat 828EL (trade name, epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.) 1010 parts, 390 parts of bisphenol A, 240 parts of polycaprolactone diol (number average molecular weight of about 1200), and dimethylbenzylamine 0.2 parts were added and reacted at 130 ° C. until the epoxy equivalent was about 1090. Next, 183 parts of thiodiethylene glycol and 90 parts of acetic acid were added and reacted at 120 ° C. for 4 hours. Then, ethylene glycol monobutyl ether was added, and the base resin No. 7 having a solid content of 71% was added. 1 was obtained.

Production Example 14 Production Example of Curing Agent In a reaction vessel, 270 parts of Cosmonate M-200 (trade name, Crude MDI, manufactured by Mitsui Chemicals, Inc.) and 25 parts of methyl isobutyl ketone were added and heated to 70 ° C. Into this, 15 parts of 2,2-dimethylolbutanoic acid was gradually added, and then 118 parts of ethylene glycol monobutyl ether was added dropwise, reacted at 70 ° C. for 1 hour, cooled to 60 ° C., and propylene glycol. 152 parts were added.
While maintaining this temperature, sampling was carried out over time, and it was confirmed by infrared absorption spectrum measurement that there was no absorption of unreacted isocyanato groups, and a curing agent having a resin solid content of 90% was obtained.

Production Example 15 Emulsion No. Production of base resin No. 1 having a solid content of 71% obtained in Production Example 13 No. 1 98.6 parts (solid content 70 parts), curing agent 33.3 parts obtained in Production Example 14 (solid content 30 parts), 3-amino-1,2,4-triazole 5 parts (solid content 5 parts) ) Was mixed and stirred uniformly, and then 15 parts of 10% acetic acid and 156.8 parts of deionized water were added dropwise over about 15 minutes with vigorous stirring to give emulsion No. 34 having a solid content of 34%. 2 was obtained.

Production Example 16 Emulsion No. Production of base resin No. 1 having a solid content of 71% obtained in Production Example 13 18.6 was mixed with 98.6 parts (solid content 70 parts) and the curing agent 33.3 parts (solid content 30 parts) obtained in Production Example 14 and stirred uniformly, then 15 parts of 10% acetic acid and 147 deionized water. The solution was added dropwise over about 15 minutes with vigorous stirring, and emulsion No. 34 having a solid content of 34% was added. 1 was obtained.

Example 1
Emulsion No. No. 1 to 309 parts (solid content 105 parts), and pigment dispersion paste No. No. 1 262 parts (solid content 131 parts) and deionized water 609 parts were added and mixed uniformly to give a 20% aqueous paint no. 1 was obtained.

Examples 2-6
In the same operation as in Example 1, with the blending contents as shown in Table 2, the water-based paint no. 2-No. 6 was obtained.

Comparative Examples 1-5
In the same operation as in Example 1, with the blending contents as shown in Table 2, the water-based paint no. 7-No. 11 was obtained.

Preparation of test plate Cold-bonded steel plate (150 mm x 70 mm x 0.8 mm) or Palbond # 3020 (manufactured by Nippon Parkerizing Co., Ltd., trade name) , Zinc phosphate treatment) on an alloyed galvanized steel sheet (150 mm x 70 mm x 0.8 mm). 1 to water-based paint No. 1 11 was applied by spraying and baked and dried at 150 ° C. for 20 minutes to obtain a test plate having a dry film thickness of 20 μm. The obtained test plate was subjected to the test according to the following test conditions. The test results are shown in Table 3.

(Note 11) Paint stability (1): As a substitute test of paint stability during continuous use of paint, 3 L of each water-based paint was stirred at 30 ° C., and after 4 weeks, the paint was filtered through a 400 mesh wire mesh to be water-based. The amount of paint residue was evaluated.
A: The filtration residue is less than 5 mg / L. O: The filtration residue is 5 mg / L or more and the filtration residue is 10 mg / L or less. Δ: The filtration residue exceeds 10 mg / L and 20 mg / L or less. 20 mg / L is exceeded.

(Note 12) Paint stability (2): As a substitute test for paint stability during continuous paint use, each water-based paint 3L is 30 ° C, and Iwata Pump PPS-102 (trade name, Iwata Co., Ltd.) as a plunger pump. The product is made of Teflon (registered trademark) tubing with a length of 3m and a diameter of 0.63cm, and each water-based paint 3L is placed in the circulation pipe for 72 hours at 30 strokes / minute. It was circulated. Then, it filtered with a 400 mesh metal-mesh and evaluated the residual amount of the aqueous coating material.
A: The filtration residue is less than 5 mg / L. O: The filtration residue is 5 mg / L or more and the filtration residue is 10 mg / L or less. Δ: The filtration residue exceeds 10 mg / L and 20 mg / L or less. 20 mg / L is exceeded.

(Note 13) Finishing property: The Ra value of the surface roughness of the test plate (material: cold-rolled steel plate) was measured using Surf Test 301 (trade name, surface roughness measuring machine manufactured by Mitutoyo Corporation).
◎: Ra value is 0.25 or less ○: Ra value exceeds 0.25 and less than 0.30 Δ: Ra value exceeds 0.30 and less than 0.35 ×: Ra value However, it exceeds 0.35.

(Note 14) Adhesiveness: 35 μm of TP-65-2 intermediate coating was applied to a test plate (material: cold-rolled steel plate) and baked at 140 ° C. for 20 minutes. Next, neoamylac 6000 (white) was coated with 35 μm and baked at 140 ° C. for 20 minutes to obtain a multilayer test plate.
The multi-layer test plate was immersed in warm water at 40 ° C. for 10 days, 2 × 2 mm square cuts were put on the surface, and 10 × 10 (pieces) cuts were evaluated for peeling with an adhesive tape.
○: No abnormality △: There is no peeling, but there is a border ×: There is peeling.

(Note 15) Corrosion protection: Cross cut scratches are made on the test plate with a knife so as to reach the base of the test plate (material: galvannealed steel plate), and this is sprayed with salt water for 480 hours according to JIS Z-2371 The test was performed, and the following criteria were evaluated based on the rust and blister width from the knife scratch. A: The maximum width of rust and blisters is less than 2.5 mm from the cut part (one side),
○: The maximum width of rust and blisters is 2.5 mm or more from the cut part and less than 3 mm (one side),
Δ: The maximum width of rust and swelling is 3 mm or more from the cut part and less than 4 mm (one side),
X: The maximum width of rust and blisters is 4 mm or more (one side) from the cut part.

(Note 16) Exposure resistance: Cross-cut flaws are applied to the electrodeposition coating film with a knife to reach the base of the test plate (material: cold-rolled steel plate, alloyed hot-dip galvanized steel plate), and the beach (Kagoshima Prefecture, Okinoerabu ) Exposure was conducted for 2 years to evaluate rust and blisters.
A: The maximum width of rust and blisters is less than 2.5 mm from the cut part (one side)
○: The maximum width of rust and blisters is 2.5 mm or more from the cut part and less than 3.0 mm (one side)
Δ: The maximum width of rust and blisters is 3.0 mm or more from the cut part and less than 4.0 mm (one side)
X: The maximum width of rust and swelling is 4.0 mm or more (one side) from the cut part.

  A coated article having excellent finish and long-term corrosion resistance can be obtained.

Claims (6)

An aqueous coating composition containing a cationic epoxy resin (A), a crosslinking agent (B), a phosphate group-containing dispersion resin (C), a zinc powder (D), a conductive filler (E), and a triazole compound (F) A thing,
Phosphoric acid group-containing dispersion resin (C) 0.1-30 parts by mass, zinc dust (D) 5-200 with respect to 100 parts by mass in total of the solid content of the cationic epoxy resin (A) and the crosslinking agent (B) An aqueous coating composition comprising 0.1 part by mass, 0.1-30 parts by mass of conductive filler (E) and 0.1-30 parts by mass of triazole compound (F). The amorphous silica fine particles (G) having undergone calcium ion exchange are contained in an amount of 1 to 200 parts by mass based on 100 parts by mass of the total solid content of the cationic epoxy resin (A) and the crosslinking agent (B). The water-based paint composition described in 1. The proportion of the crosslinking agent (B) to the cationic epoxy resin (A) is based on the total solid content of 100 parts by weight of the cationic epoxy resin (A) and the crosslinking agent (B). The aqueous coating composition according to claim 1 or 2, wherein / crosslinking agent (B) = 95/5 (parts by mass) to 50/50 (parts by mass). The aqueous coating composition according to any one of claims 1 to 3, wherein the cationic epoxy resin (A) is a cationic epoxy resin containing an onium salt, and the crosslinking agent (B) is a blocked polyisocyanate compound. . A coating film forming method, wherein the water-based coating composition according to any one of claims 1 to 4 is applied to an object to be coated by spraying or electrostatic coating. A coated article coated by the coating film forming method according to claim 5.