JP2022178302A - Coating composition - Google Patents

Abstract

To provide a coating composition for forming, on the surface of various materials such as a substrate, a hydrophilic film having excellent hydrophilicity (and its persistence) and corrosion resistance, and also having excellent water resistance.SOLUTION: A coating composition contains a hydrophilic resin (A), a sulfonic acid-based surfactant (B), a hydrophobic resin (C) and a crosslinker (D). Relative to the total solid content of the hydrophilic resin (A), sulfonic acid-based surfactant (B), hydrophobic resin (C) and crosslinker (D), the total solid content of the hydrophilic resin (A) and sulfonic acid-based surfactant (B) is 10-35 mass%.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a coating composition having excellent hydrophilicity and corrosion resistance.

Various materials such as molded products such as vehicles, vehicle parts, building materials, home appliance parts, castings, sheets, coils or molded products are subjected to surface treatment to impart various performances.

Such properties include, for example, corrosion resistance, hydrophilicity, and water repellency. Among them, light metals (especially aluminum and its alloy materials (hereinafter referred to as aluminum materials) are widely used for home electric appliances and automobiles because of their light weight and excellent workability.

In particular, aluminum materials are used for various metal materials because of their high thermal conductivity, and are required to have hydrophilicity, corrosion resistance, moisture resistance, durability, and the like.

For example, aluminum fins used in air conditioning equipment such as air conditioners require surface hydrophilicity and corrosion resistance. The ability to maintain corrosion resistance (sustained hydrophilicity) is required. Furthermore, it is also required to have excellent water resistance in order to prevent dissolution and outflow of the hydrophilized film formed by the surface treatment.

As a hydrophilic treatment composition excellent in hydrophilicity (durability), corrosion resistance, etc., for example, Patent Document 1 discloses a hydrophilic treatment agent in which polyglycerin and a high acid value acrylic resin are combined.

Further, Patent Document 2 discloses a hydrophilizing composition containing (A) water-dispersible silica, (B) a water-soluble or water-dispersible organic polymer resin, and (C) a cross-linking agent. there is

Japanese Patent Application Laid-Open No. 2001-323257 Japanese Patent Application Laid-Open No. 2001-247822

However, with these conventionally proposed surface treatment compositions, it is not possible to obtain a hydrophilic film that satisfies sufficient hydrophilicity (durability), corrosion resistance, and water resistance. is not currently developed.

The present invention has been made to solve the above problems, and its object is to have excellent hydrophilicity (durability) and corrosion resistance on the surface of various materials such as substrates, and further to provide water resistance. To provide a coating composition capable of forming a hydrophilic film having excellent properties.

The present inventors have made intensive studies to solve the above problems. Hydrophilic resin (A) and sulfonic acid surfactant with respect to the total solid content of hydrophilic resin (A), sulfonic acid surfactant (B), hydrophobic resin (C) and cross-linking agent (D) The inventors have found that the above problems can be solved by a coating composition (B) having a total solid content of 10 to 35% by mass, and have completed the present invention.

That is, the present invention relates to the following contents.

1. A hydrophilic resin (A), a sulfonic acid-based surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D) are contained, and the hydrophilic resin (A), the sulfonic acid-based surfactant (B), A paint in which the total solid content of the hydrophilic resin (A) and the sulfonic acid-based surfactant (B) is 10 to 35% by mass with respect to the total solid content of the hydrophobic resin (C) and the cross-linking agent (D). Composition.

2. The hydrophilic resin (A) contains at least one hydrophilic acrylic polymer in which the total amount of amide group-containing monomers is 50% by mass or more relative to the total amount of monomer components constituting the polyacrylamide resin or polymer. Item 1. The coating composition according to item 1.

3. 3. The coating composition according to item 1 or 2, wherein the hydrophilic resin (A) has a weight average molecular weight of 5,000 to 350,000.

4. 4. The coating composition according to any one of items 1 to 3 above, wherein the hydrophobic resin (C) contains at least one selected from an acrylic resin (C1), a polyurethane resin (C2), and an epoxy resin (C3). .

5. The total solid content of each component relative to the total solid content of the hydrophilic resin (A), the sulfonic acid surfactant (B), the hydrophobic resin (C) and the cross-linking agent (D) is the hydrophilic resin (A) 5 to 25% by mass, 5 to 15% by mass of the sulfonic acid surfactant (B), 20 to 60% by mass of the hydrophobic resin (C), and 20 to 60% by mass of the cross-linking agent (D). The coating composition according to any one of .

Since the coating composition of the present invention contains a hydrophilic resin (A), a sulfonic acid surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D), it is hydrophilic and corrosion resistant. An excellent coating film can be obtained. In addition, unlike conventional hydrophilizing surface treatment agents that contain a large amount of hydrophilization-imparting components, the hydrophilic surface treatment agent has at least a high content of hydrophilic resin (A) and sulfonic acid-based surfactant (B), which are hydrophilicity-imparting components. Since it can impart properties, it is possible to obtain a coating film that is also excellent in water resistance.

As described above, according to the present invention, there is provided a coating composition that can form a coating film that is excellent in hydrophilicity (durability) and corrosion resistance, and also excellent in water resistance, on various materials such as substrates. can provide.

The present invention contains a hydrophilic resin (A), a sulfonic acid surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D), and the hydrophilic resin (A) and the sulfonic acid surfactant (B), relative to the total solid content of the hydrophobic resin (C) and the cross-linking agent (D), the total solid content of the hydrophilic resin (A) and the sulfonic acid surfactant (B) is 10 to 35 mass. % (hereinafter sometimes referred to as the present paint for short).

The contents of the present invention will be described in detail below.

<Paint composition>
Hydrophilic resin (A)
The hydrophilic resin (A) in the coating composition of the present invention is a resin having a hydrophilic group. It is a functional group that harmonizes. Specific examples of the hydrophilic group include a carboxyl group, a hydroxyl group, an amino group, an amide group, a sulfate group, a sulfonic acid group, an oxyalkylene group, and a functional group serving as a precursor thereof.

In the present invention, the hydrophilic resin (A) is defined as follows.

The hydrophilic resin (A) is a resin that satisfies either one of the requirements 1 and 2 below.
1. The content of hydrophilic groups in the resin is 4000 mmol/kg or more2. The content of the alkylene oxide [(RO) _n ; n≧5 R is an alkylene group] structural unit having 5 or more repeating units in the resin is 5% by mass or more Specific hydrophilic resins include, for example, polyvinyl alcohol and polyethylene Vinyl alcohol-based polymers such as vinyl alcohol, polyvinylpyrrolidone-based polymers such as polyvinylpyrrolidone, cellulose-based polymers such as cellulose, cellulose acetate, carboxymethylcellulose, and cellulose triacetate, polyethylene glycol-based polymers such as polyethylene glycol and polyethylene oxide, polyacrylic acid , acrylic polymers such as sodium polyacrylate, sodium polyvinyl sulfonate, polystyrene sulfonic acid, polyacrylamide resins, and acrylic polymers having at least one selected from polyoxyalkylene chains, amide groups, hydroxyl groups and acid groups A coalescence (hereinafter simply referred to as a hydrophilic acrylic polymer) and the like can be mentioned.

These can be used alone or in combination of two or more.

Among the above hydrophilic resins, polyacrylamide resins and hydrophilic acrylic polymers are preferred from the viewpoint of compatibility between hydrophilicity and corrosion resistance.

In the present invention, the polyacrylamide resin and the hydrophilic acrylic polymer are polyacrylamide resins, provided that the total amount of (meth)acrylamide is 70% by mass or more with respect to the total amount of monomer components constituting the polymer. If it is less than 70%, it shall be defined as a hydrophilic acrylic polymer.

In this specification, "(meth)acrylate" means "acrylate or methacrylate". "(Meth)acrylamide" means "acrylamide or methacrylamide".

For the polyacrylamide resin, use a polymer obtained by polymerizing a mixture of radically polymerizable monomers containing 70% by mass or more of (meth)acrylamide with respect to the total amount of the radically polymerizable monomers constituting the resin. For example, it may be a homopolymer of (meth)acrylamide or a copolymer of (meth)acrylamide and other radically polymerizable monomers.

Specifically, the polyacrylamide resin is, for example, a mixture of (meth)acrylamide and, if necessary, other radically polymerizable monomers in the presence of a polymerization initiator (azo, peroxide, redox type, etc.). It can be obtained by polymerizing in a solvent such as water or an organic solvent under the following conditions. The above polymerization temperature can be varied depending on the type of polymerization initiator used, etc., but usually a temperature in the range of about 50 to about 200°C, more preferably 90 to 160°C is suitable, and the reaction time is 0.5°C. About 5 to 10 hours.

Commercially available polyacrylamide resins can also be used, for example, Haricoat G-50, Haricoat G-51, Haricoat 1057 (trade names of Harima Kasei), Polymerset 305, Polymerset 500, Polymerset 512 ( As mentioned above, Arakawa Chemical Industries, Ltd. (trade name) and the like can be mentioned.

Other radical copolymerizable monomers that can be used in the production of the polyacrylamide resin include, for example, cationic vinyl monomers, anionic vinyl monomers, N-substituted (meth)acrylamides and other vinyl monomers.

Examples of the cationic vinyl monomer include N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylamino Examples include vinyl monomers having a tertiary amino group such as propyl(meth)acrylamide, salts thereof, allylamine compounds such as diallylamine, triallylamine and allylamine, and salts thereof.

Examples of the anionic vinyl monomer include monocarboxylic acids such as (meth)acrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, muconic acid and citraconic acid; vinylsulfonic acid and styrenesulfonic acid. , 2-acrylamido-2-methylpropanesulfonic acid; or sodium salts and potassium salts of these various organic acids.

The N-substituted (meth)acrylamide is not particularly limited as long as it is an N-substituted (meth)acrylamide other than a cationic vinyl monomer, and known ones can be used. ) acrylamide, N,N-diethyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nt -Butyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide ) acrylamide, N-isobutoxymethyl(meth)acrylamide, N-hexyloxymethyl(meth)acrylamide, N-isohexyloxymethyl(meth)acrylamide and the like.

The above other vinyl monomers are not particularly limited as long as they are vinyl monomers other than cationic vinyl monomers, anionic vinyl monomers, and N-substituted (meth)acrylamides, and known ones can be used. acrylic acid alkyl esters such as meth)methyl acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; allyl-based monomers containing allyl groups such as allyl alcohol; (meth)acrylonitrile; methylene bis (meth) bisacrylamide-based monomers such as acrylamide and ethylenebis(meth)acrylamide; diacrylate-based monomers such as ethylene glycol di(meth)acrylate and diethylene glycol di(meth)acrylate; divinylbenzene; 1,3,5-triacryloyl Polyfunctional vinyl monomers such as hexahydro-S-triazine, triallyl isocyanurate and tetramethylolmethane tetraacrylate can be mentioned.

As used herein, "(meth)acrylic acid" means "acrylic acid or methacrylic acid".

In the polyacrylamide resin, the total amount of (meth)acrylamide is preferably 80% by mass or more, particularly 90% by mass or more, relative to the total amount of the monomer components constituting the polymer from the viewpoint of hydrophilicity.

As the hydrophilic acrylic polymer, a polymer obtained by polymerizing a mixture of radically polymerizable monomers can be used. Examples of radically polymerizable monomers include the following monomers.

M1. Polymerizable unsaturated monomer having a polyoxyalkylene chain or polyvinylpyrrolidone chain M2. (Meth)acrylamide, N-methylol(meth)acrylamide or N-alkoxymethyl(meth)acrylamide M3. Acidic group-containing polymerizable unsaturated monomer M4. Hydroxyl group-containing polymerizable unsaturated monomer M5.1 Monomer having two or more polymerizable unsaturated double bonds in the molecule M6. Polymerizable Unsaturated Monomers Other Than M1 to M5 Above M1 is a compound having at least one polymerizable double bond and a polyoxyalkylene chain or a polyvinylpyrrolidone chain in one molecule.

Examples of the N-alkoxymethyl(meth)acrylamide of M2 include N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, N-propoxymethyl(meth)acrylamide, N-isopropoxymethyl(meth)acrylamide, N-isopropoxymethyl(meth)acrylamide, ) acrylamide, N-butoxymethyl(meth)acrylamide, N-isobutoxymethyl(meth)acrylamide, N-hexyloxymethyl(meth)acrylamide, N-isohexyloxymethyl(meth)acrylamide.

The above M3 can be used without particular limitation as long as it is a compound having at least one acidic group and one polymerizable unsaturated group in one molecule. Specifically, acrylic acid, methacrylic acid, crotonic acid, Carboxyl group-containing polymerizable unsaturated monomers such as itaconic acid, maleic acid and fumaric acid; sulfonic acid group-containing polymerizable unsaturated monomers such as vinylsulfonic acid, styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid; or Sodium salts, potassium salts and the like of these various organic acids can be mentioned. The acidic group-containing polymerizable unsaturated monomer can also contribute to the curability of the hydrophilic coating composition.

Specific examples of M4 include acrylic acids such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Alternatively, hydroxyalkyl esters of methacrylic acid having 2 to 8 carbon atoms can be used. A hydroxyl group-containing polymerizable unsaturated monomer can also contribute to the curability of the hydrophilic coating composition.

Specific examples of M5 include methylenebisacrylamide, methylenebismethacrylamide, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3- Butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, divinylbenzene, allyl(meth)acrylate and the like can be mentioned. Among these, methylenebisacrylamide and methylenebismethacrylamide can be preferably used from the viewpoint of dispersion stability and hydrophilicity when polymer fine particles are formed.

Specific examples of M6 include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, ) C1-C24 alkyl or cycloalkyl esters of acrylic acid or methacrylic acid such as acrylates; polymerizable unsaturated nitriles such as acrylonitrile and methacrylonitrile; styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, etc. aromatic vinyl compounds; nitrogen-containing alkyl esters of acrylic acid or methacrylic acid having 2 to 8 carbon atoms such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; ethylene, α-olefins such as propylene; diene compounds such as butadiene and isoprene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as ethyl vinyl ether and n-propyl vinyl ether; N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, (Meth)acrylamide unsaturated compounds such as Nn-butylacrylamide; γ-methacryloyloxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 2-styrylethyltri Examples include unsaturated compounds having a hydrolyzable silyl group such as methoxysilane and vinyltris(methoxyethoxy)silane, and unsaturated compounds having an epoxy group such as glycidyl (meth)acrylate and allyl glycidyl ether.

In the hydrophilic acrylic polymer, the total amount of the amide group-containing monomer is preferably 50% by mass or more, particularly 60% by mass or more, based on the total amount of the monomer components constituting the polymer from the viewpoint of hydrophilicity.

The above monomers may be used alone or in combination of two or more.

Synthesis of a hydrophilic acrylic polymer is usually carried out in the presence of a radical polymerization initiator. As the radical polymerization initiator, those known per se can be used, and the amount used is preferably within the range of 0.2 to 5% by mass based on the total amount of the monomers.

The polymerization temperature can be varied depending on the type of polymerization initiator to be used, etc., but usually a temperature in the range of about 50 to about 160° C., more preferably 90 to 160° C. is preferred, and the reaction time is 0.5. It can be about 10 hours.

In the hydrophilic resin (A), the content of hydrophilic groups in the resin is preferably 4000 mmol/kg or more, preferably 6000 mmol/kg or more, particularly 8000 mmol/kg or more, from the viewpoint of hydrophilicity.

The weight average molecular weight of the hydrophilic resin (A) is preferably in the range of 5,000 to 350,000, particularly 15,000 to 350,000, more particularly 15,000 to 200,000 from the viewpoint of corrosion resistance and hydrophilicity.

In this specification, the average molecular weight is a value obtained by converting the retention time measured using a gel permeation chromatograph into the molecular weight of polystyrene based on the retention time of standard polystyrene with a known molecular weight measured under the same conditions.

From the viewpoint of a cross-linking reaction with a cross-linking agent (D) described later, the hydrophilic resin (A) preferably has a functional group reactive with the cross-linking agent (D). Specifically, for example, when the cross-linking agent (D) is a melamine resin or a polyisocyanate resin, it preferably contains hydroxyl groups reactive with these.

The hydrophilic resin (A) can be dissolved or dispersed in water by adding a neutralizing agent as necessary.

When the hydrophilic resin (A) is used as an aqueous dispersion, the average particle size should be in the range of 30 to 700 nm, particularly 40 to 600 nm, and more particularly 120 to 500 nm from the viewpoint of dispersion stability, coating workability, etc. preferred from

The average particle size can be measured by a particle size measuring device such as Coulter model N4MD (manufactured by Beckman Coulter, trade name).

Sulfonic acid surfactant (B)
A sulfonic acid surfactant is an anionic surfactant having a —SO ₃ — group in its molecular structure. Specifically, for example, sulfonate-based, sulfate-based, and sulfosuccinate-based surfactants can be used.

Examples of sulfonate-based surfactants include alkyldiphenylether disulfonate-based and alkylbenzenesulfonate-based surfactants.

Alkyldiphenyletherdisulfonic acid surfactants include alkyldiphenyletherdisulfonic acids and metal salts thereof. Among these, alkyldiphenyl ether disulfonic acid sodium salt can be preferably used in particular from the viewpoint of improving the durability of hydrophilicity.

Commercially available alkyldiphenyl ether disulfonic acid-based surfactants include Pelex SS-L, Pelex SS-H (Kao Corporation), Newcol 261-A, and Newcol 271-A (Nippon Emulsifier Co., Ltd.). be able to.

Alkylbenzenesulfonate-based surfactants include alkylbenzenesulfonic acids and metal salts thereof. Among these, alkylbenzenesulfonic acid sodium salt can be preferably used in particular from the viewpoint of improving the durability of hydrophilicity.

Commercially available alkylbenzene sulfonate-based surfactants include Newcol 210, Newcol 220-L (Nippon Nyukazai Co., Ltd.), Neoperex G-15, Neoperex G-25 (Kao Corporation), and the like. be able to.

Examples of the sulfate-based surfactant include polyoxyethylene alkyl ether sulfate-based surfactants.

Examples of polyoxyethylene alkyl ether sulfate salt-based surfactants include polyoxyethylene alkyl ether sulfate esters and metal salts thereof. Among these, sodium salt of polyoxyethylene alkyl ether sulfate is particularly preferable from the viewpoint of improving the durability of hydrophilicity.

Examples of commercially available polyoxyethylene alkyl ether sulfate salt-based surfactants include Newcoal 707SN, Newcole 714SF, Newcole 2308SF, Newcole 2360SN (Nippon Nyukazai Co., Ltd.), Latemul E-118B, and Latemul E. -150, Latemul WX, Latemul PD-140 (Kao Corporation), Levenol WX (Kao Chemicals) and the like.

Examples of the sulfosuccinate-based surfactant include dialkylsulfosuccinic acid and metal salts thereof.

Specifically, for example, monoalkylsulfosuccinic acid ester salts, dialkylsulfosuccinic acid ester salts, alkyl sulfosuccinic acid di-salts, polyoxyethylene alkyl sulfosuccinic acid di-salts, alkylamine oxide sodium bistridecyl sulfosuccinate, dioctyl sodium sulfosuccinate, dihexyl sodium sulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium diamylsulfosuccinate, sodium diisobutylsulfosuccinate, disodium isodecylsulfosuccinate, disodium N-octadecylsulfosuccinate amide, N-(1,2-dicarboxyethyl)-N- Tetrasodium octadecylsulfosuccinate and the like can be mentioned. Among these, sodium dialkylsulfosuccinate can be particularly preferably used from the viewpoint of improving the durability of hydrophilicity.

Commercially available sulfosuccinate-based surfactants include Pelex OT-P, Pelex TR, Pelex CS, Pelex TA (Kao Corporation), Newcole 290-A, Newcole 290-M, and Newcole 291-M. , New Cole 291-PG, New Cole 291-GL, New Cole 292-PG, New Cole 293 (Nippon Emulsifier Co., Ltd.), Neo Cole SW-C, Neo Cole YSK, Neo Cole P (Daiichi Kogyo Seiyaku Co., Ltd.) can be done.

Among the above sulfonic acid-based surfactants, from the viewpoint of hydrophilicity and corrosion resistance, it is preferable to use alkyldiphenyl ether disulfonic acid-based and sulfosuccinate-based surfactants. Moreover, it is more preferable to use both together.

When an alkyldiphenyletherdisulfonic acid-based surfactant and a sulfosuccinate-based surfactant are used in combination, based on the total solid content of both surfactants, alkyldiphenyletherdisulfonic acid-based surfactant/sulfosuccinate-based surfactant = 80/ 20 to 50/50 (mass ratio), preferably 70/30 to 55/45 (mass ratio), from the viewpoint of maintaining hydrophilicity.

Hydrophobic resin (C)
The hydrophobic resin (C) in the coating composition of the present invention is a resin that does not have a hydrophilic group or has a small amount of hydrophilic groups. A hydrophilic group is a functional group that ionizes in water to form ions, or a functional group that hydrates through hydrogen bonding without being ionized. Specific examples of the hydrophilic group include a carboxyl group, a hydroxyl group, an amino group, an amide group, a sulfate group, a sulfonic acid group, an oxyalkylene group, and a functional group serving as a precursor thereof.

In the present invention, the hydrophobic resin (C) is defined as follows.

The hydrophobic resin (C) is a resin that satisfies both requirements 1 and 2 below.

1. 2. The content of hydrophilic groups in the resin is less than 4000 mmol/kg. The content of the alkylene oxide [(RO) _n ; n≧5 R is an alkylene group] structural unit having 5 or more repeating units in the resin is less than 5% by mass Specific hydrophobic resin (C) includes, for example, polyolefin Resins, polyester resins, epoxy resins, polyurethane resins, acrylic resins, polystyrene resins, polycarbonate resins and the like can be used.

These can be used alone or in combination of two or more.

Among the above resins, acrylic resin (C1), polyurethane resin (C2), and epoxy resin (C3) can be preferably used from the viewpoint of corrosion resistance and hot water resistance.

Acrylic resin (C1)
The acrylic resin (C1) is a hydrophobic acrylic resin and can be used without any particular limitation as long as it satisfies requirements 1 and 2 of the hydrophobic resin (C). As the copolymerizable monomer, those described for the hydrophilic acrylic polymer of the hydrophilic resin (A) can be used in the same manner, and can be synthesized in the same manner as described for the hydrophilic acrylic polymer. can be done.

Polyurethane resin (C2)
The polyurethane resin (C2) is generally a polyurethane composed of a polyol such as an acrylic polyol, a polyester polyol, or a polyether polyol and a diisocyanate. It can be synthesized by chain extension in the presence of an agent. Those that are stably dispersed or dissolved in water can be preferably used.

The polyurethane resin (C2) can be stably dispersed or dissolved in water by, for example, the following method.

(1) A method of imparting hydrophilicity by introducing an ionic group such as a hydroxyl group, an amino group, or a carboxyl group into the side chain or end of a polyurethane polymer and dispersing or dissolving it in water by self-emulsification (2) Completion of the reaction or a polymer whose terminal isocyanate groups are blocked with a blocking agent such as oxime, alcohol, phenol, mercaptan, amine, sodium bisulfite, etc., is forcibly dispersed in water using an emulsifier and mechanical shearing force (3 ) A method in which a urethane prepolymer having a terminal isocyanate group is mixed with water, an emulsifier and an elongating agent, and a mechanical shearing force is used to simultaneously disperse and polymerize it. A method of dispersing or dissolving in water as a water-soluble polyurethane by using such a water-soluble polyol. All are manufactured by Dainippon Ink and Chemicals), Superflex 100, Superflex 110, Superflex 150, Superflex F-8438D, Superflex 420 (all manufactured by Daiichi Kogyo Seiyaku), Adeka Bonditer HUX-232, ADEKA BONTITER HUX-260, ADEKA BONTITER HUX-320, ADEKA BONTITER HUX-350, ADEKA BONTITER HUX-540, ADEKA BONTITER UX-206 (all manufactured by Asahi Denka Co., Ltd.) and the like.

Epoxy resin (C3)
The epoxy resin (C3) is typically a copolymer of a polyphenol compound and epihalohydrin, such as a resin obtained by reacting a polyphenol compound and epichlorohydrin. Examples of the polyphenol compounds include bis(4-hydroxyphenyl)-2,2-propane (also referred to as “bisphenol A”), 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)methane (“bisphenol F”), 4,4-dihydroxydiphenylsulfone (also called “bisphenol S”), and the like. A bisphenol A type epoxy resin can be preferably used from the viewpoint of corrosion resistance.

A bisphenol A type epoxy resin can be obtained by polymerization of bisphenol A and epichlorohydrin. A bisphenol A type epoxy resin can also be obtained by a two-stage polymerization method in which bisphenol A is added to a bisphenol A type epoxy resin having a relatively low epoxy equivalent.

The bisphenol A type epoxy resin having a relatively low epoxy equivalent generally has an epoxy equivalent of about 160 to about 2,000. Commercial products thereof include jER828EL and jER1001 manufactured by Japan Epoxy Resin Co., Ltd. , jER1004, jER1007; Araldite AER250, Araldite AER260, Araldite AER6071, Araldite AER6004, Araldite AER6007 manufactured by Asahi Kasei Epoxy; -4100, ADEKA RESIN EP-5100 and the like.

Also, the bisphenol A type epoxy resin may be a modified epoxy resin obtained by modifying a bisphenol A type epoxy resin with a dibasic acid. In this case, the bisphenol A type epoxy resin to be reacted with the dibasic acid has a number average molecular weight of about 2,000 to about 8,000 and an epoxy equivalent of about 1,000 to about 4,000. can be preferably used.

Examples of the dibasic acid include the following general formula:
HOOC-(CH ₂ ) _n -COOH, where n is an integer from 1 to 12
Specific examples include succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydrophthalic acid and the like.

The bisphenol A-type modified epoxy resin is obtained by reacting a mixture of the bisphenol A-type epoxy resin and a dibasic acid in the presence of an esterification catalyst such as tri-n-butylamine and an organic solvent at a reaction temperature of about 120. to about 180° C. for about 1 to about 4 hours.

The acrylic-modified epoxy resin (C3a) is an epoxy resin modified with an acrylic resin, and can be produced, for example, by the following methods (1) to (3).

(1) A method of graft polymerizing a polymerizable unsaturated monomer, such as an acrylic monomer, to an epoxy resin by a hydrogen abstraction reaction. (2) A carboxyl group-containing polymerizable unsaturated monomer, such as a carboxyl group, to the epoxy group of the epoxy resin. A method of obtaining an acrylic-modified epoxy resin by subjecting the contained acrylic monomer to an esterification reaction and polymerizing the acrylic monomer with the double bond introduced into the epoxy resin. (3) Reacting the epoxy resin with a carboxyl group-containing acrylic resin. to obtain an acrylic-modified epoxy resin
Among these, the acrylic-modified epoxy resin produced by the method (3) is preferable from the viewpoint of forming a coating film excellent in hydrophilicity and corrosion resistance.

The production of the acrylic-modified epoxy resin by method (3) is described below.

The bisphenol type epoxy resin used for the production of the acrylic-modified epoxy resin (C3a) has a number average molecular weight of about 2,000 to 2,000 from the viewpoint of the dispersion stability in the aqueous medium of the obtained acrylic-modified epoxy resin (C3a). preferably in the range of about 30,000, especially in the range of about 5,000 to about 30,000, preferably in the range of about 1,000 to about 10,000, especially in the range of about 2,500 to about 10,000. .

The carboxyl group-containing acrylic resin used for producing the acrylic-modified epoxy resin (C3a) by reacting with the epoxy resin is a carboxyl group-containing polymerizable inert such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid. It is an acrylic copolymer containing a saturated monomer as a monomer skeleton.

The acrylic copolymer has a weight-average molecular weight of about 5,000 to about 100,000, particularly about 10,000 to about 100,000, from the viewpoint of stability in aqueous media and corrosion resistance of the coating film. and an acid value in the range of about 150 to about 700 mgKOH/g, especially about 200 to about 500 mgKOH/g.

Examples of other monomers other than the carboxyl group-containing polymerizable unsaturated monomers used for producing the carboxyl group-containing acrylic resin include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl Acrylic acid or methacrylic such as (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, benzyl (meth)acrylate, stearyl (meth)acrylate, etc. C 1-22 alkyl esters of acids; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate; aromatic vinyl monomers such as styrene, α-methylstyrene, vinyl toluene; 2-hydroxyethyl (meth) acrylate, hydroxy Hydroxyalkyl (meth)acrylates such as propyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyamyl (meth)acrylate and hydroxyhexyl (meth)acrylate, and hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate Hydroxyl group-containing acrylic monomers such as caprolactone-modified alkyl (meth)acrylate having a hydroxyl group, obtained by subjecting 1 to 5 mol of ε-caprolactone to ring-opening addition reaction per 1 mol; acrylamide, methacrylamide, N-methoxymethyl (meth) Acrylamide, N-ethoxymethyl (meth)acrylamide, Nn-propoxymethyl (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, Nn-butoxymethyl (meth)acrylamide, N-sec-butoxymethyl ( acrylamide-based monomers such as meth)acrylamide and N-tert-butoxymethyl(meth)acrylamide;

The carboxyl group-containing acrylic resin is obtained by adding a monomer mixture of the carboxyl group-containing polymerizable unsaturated monomer and the other monomers, for example, in an organic solvent in the presence of a radical polymerization initiator and/or a chain transfer agent. , at about 80 to about 150° C. for about 1 to about 10 hours.

Examples of the polymerization initiator include organic peroxide initiators and azo initiators. Examples of the organic peroxide-based initiator include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxide, t-butylperoxybenzoate, t-amylperoxy-2- Ethylhexanoate and the like can be mentioned, and examples of azo initiators include azobisisobutyronitrile, azobisdimethylvaleronitrile and the like. Examples of the chain transfer agent include α-methylstyrene dimer and mercaptans.

The acrylic-modified epoxy resin (C3a) is obtained by mixing a bisphenol-type epoxy resin and a carboxyl group-containing acrylic resin in an organic solvent, for example, with an esterification catalyst, for example, tertiary amines such as triethylamine and dimethylethanolamine, It can be obtained by esterification at about 80 to about 120° C. for about 0.5 to about 8 hours in the presence of a trialkylphosphine such as triphenylphosphine.

In the acrylic-modified epoxy resin (C3a), the mass ratio of the bisphenol-type epoxy resin and the carboxyl group-containing acrylic resin may be appropriately selected according to the hydrophilicity, corrosion resistance, etc., but the bisphenol-type epoxy resin/carboxyl group-containing acrylic resin The solid content mass ratio of the resin is preferably in the range of about 10/90 to about 95/5, particularly about 20/80 to about 90/10.

In the hydrophobic resin (C), the content of hydrophilic groups in the resin is preferably less than 4000 mmol/kg, preferably less than 3000 mmol/kg, particularly less than 2000 mmol/kg, from the viewpoint of hydrophilicity and water resistance.

The weight average molecular weight of the hydrophobic resin (C) is preferably in the range of 8,000 to 200,000, particularly 10,000 to 150,000, from the viewpoint of corrosion resistance.

The hydrophobic resin (C) preferably has a functional group reactive with the cross-linking agent (D) from the viewpoint of cross-linking reaction with the cross-linking agent (D) described below. Specifically, for example, when the cross-linking agent (D) is a melamine resin or a polyisocyanate resin, it preferably contains hydroxyl groups reactive with these.

Hydrophobic resin (C) can be dissolved or dispersed in water by adding a neutralizing agent as necessary.

When the hydrophobic resin (C) is used as an aqueous dispersion, the average particle size should be in the range of 100 to 1000 nm, particularly 110 to 900 nm, more particularly 120 to 800 nm, from the viewpoint of dispersion stability, coating workability, etc. preferred from

Crosslinking agent (D)
The cross-linking agent (D) is a compound having functional groups that react with the hydrophilic resin (A) and/or the hydrophobic resin (C). Generally, the molecule has two or more functional groups that react with the hydrophilic resin (A) or the hydrophobic resin (C).

It is possible to enhance the curability of the coating composition of the present invention and improve the coating film properties such as corrosion resistance and water resistance, particularly water resistance of the resulting coating film.

Examples of the cross-linking agent (D) include amino resins, phenol resins, polyisocyanate compounds, blocked polyisocyanate compounds, oxazoline group-containing resins, polyepoxy compounds, and carbodiimide compounds.

Among these cross-linking agents (D), at least one selected from amino resins and phenol resins can be preferably used from the viewpoint of water resistance.

Examples of amino resins include melamine resins, benzoguanamine resins, and urea resins. Among them, the melamine resin (D1) is particularly preferably used from the viewpoint of hydrophilicity and corrosion resistance.

For melamine resins, for example, melamine resins obtained by etherifying the methylol group of a methylolated melamine resin with a monohydric alcohol having 1 to 8 carbon atoms can be preferably used. The etherified melamine resin may be a methylolated melamine resin in which all the methylol groups are etherified, or may be partially etherified with residual methylol groups and imino groups.

Specific examples of amino resins include fully alkyl type methyl/butyl mixed etherified melamine resin, methylol group type methyl/butyl mixed etherified melamine resin, imino type methyl/butyl mixed etherified melamine resin, and fully alkyl type methylated melamine resin. , imino group type methylated melamine resin, methylated urea resin, butylated urea resin, methylated benzoguanamine resin, butylated benzoguanamine resin, and the like. These amino resins can be used alone or in combination of two or more.

Examples of commercially available amino resins include Cymel 232, Cymel 232S, Cymel 235, Cymel 236, Cymel 238, Cymel 266, Cymel 267, Cymel 285, and the like; Cymel 272, etc.; methylol group type methyl/butyl mixed etherified melamine resin; imino type methyl/butyl mixed etherified melamine resin such as Cymel 202, Cymel 207, Cymel 212, Cymel 253, Cymel 254; Cymel 300, Cymel 301, Cymel 303, Cymel 350, etc.; Cymel 325, Cymel 327, Cymel 701, Cymel 703, Cymel 712, Cymel 254, Cymel 253, Cymel 212, Cymel 1128, etc. (the above, Daicel · Allnex Co., Ltd., trade name), Yuban 20SE60 (manufactured by Mitsui Cytec Co., Ltd., butyl etherified melamine resin),
Methylated benzoguanamine resins such as Nikalac BL-60 (manufactured by Sanwa Chemical Co., Ltd.), butylated benzoguanamine resins such as Super Beckamine TD-126 and Super Beckamine 15-594 (manufactured by DIC Corporation),
Methylated urea resins such as Cymel U-65 (manufactured by Daicel Allnex), Nicalac MX-270, Nicalac MX-280, Nicalac MX-290 (manufactured by Sanwa Chemical Co., Ltd.), Nicalac MX-279 (Sanwa Chemical company), Uvan 10S60, Uvan 10R (manufactured by Mitsui Cytec Co., Ltd.), Beckamin P-138, Beckamin P-196-M, Beckamin G-1850 (manufactured by DIC), etc. can be mentioned.

Phenolic resins are generally resins obtained by condensation reaction of phenolic compounds such as phenol, cresol, and bisphenol A with aldehydes such as formaldehyde in the presence of acidic or basic catalysts. type phenolic resin, and those condensed in the presence of a basic catalyst are called resol type phenolic resins.

Both a novolak-type phenolic resin and a resol-type phenolic resin can be used in the coating composition of the present invention. Moreover, resins into which methylol groups have been introduced are also included, and phenolic resins obtained by alkyl-etherifying some or all of the introduced methylol groups with alcohols having 6 or less carbon atoms can also be used.

Commercially available phenol resins include SUMILITERESIN PR-HF-3, SUMILITERESIN PR-HF-6, SUMILITERESIN PR-53194, SUMILITERESIN PR-53195, SUMILITERESIN PR-54869, SUMILITERESIN PR-16382, SUMILITERESIN PR-51939, and SUMILITERESIN PR-51939. 53153, SUMILITERESIN PR-53364, SUMILITERESIN PR-53365, SUMILITERESIN PR-50702 (manufactured by Sumitomo Bakelite Co., Ltd.); ２０９０、ＰＨＥＮＯＬＩＴＥ ＶＨ－４１５０、ＰＨＥＮＯＬＩＴＥ ＶＨ－４１７０、ＰＨＥＮＯＬＩＴＥ ＶＨ－４２４０、ＰＨＥＮＯＬＩＴＥ ＫＨ－１１６０、ＰＨＥＮＯＬＩＴＥ ＫＨ－１１６３、ＰＨＥＮＯＬＩＴＥ ＫＨ－１１６５、ＰＨＥＮＯＬＩＴＥ ＴＤ-２０９３－６０Ｍ、ＰＨＥＮＯＬＩＴＥ ＴＤ－２０９０－６０Ｍ、ＰＨＥＮＯＬＩＴＥ ＬＦ－４７１１ , PHENOLITE LF-6161, PHENOLITE LF-4871, PHENOLITE LA-7052, PHENOLITE LA-7054, PHENOLITE LA-7751, PHENOLITE LA-1356, PHENOLITE LA-3018-50P (manufactured by DICK); , Shownol BRG-555, Shownol BRG-556, Shownol BRG-558, Shownol CKM-923, Shownol CKM-983, Shownol BKM-2620, Shownol BRL-2854, Shownol BRG-5590M, Shownol Noll CKS-3898, Shounol CKS-3877A, Shounol CKM-937 (manufactured by Showa Polymer Co., Ltd.) and the like can be mentioned.

A polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, and specifically includes aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; tetramethylene diisocyanate, Aliphatic diisocyanates such as hexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate; cycloaliphatic diisocyanates such as methylene bis(cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate, cyclohexane diisocyanate and cyclopentane diisocyanate; biuret-type addition of said polyisocyanates. products, isocyanuric ring type adducts; preforms containing free isocyanate groups obtained by reacting these polyisocyanates with low-molecular-weight or high-molecular-weight polyol compounds (e.g., acrylic polyols, polyester polyols, polyether polyols, etc.) in excess of isocyanate groups A polymer etc. can be mentioned.

The blocked polyisocyanate compound is a phenol compound, an oxime compound, an active methylene compound, a lactam compound, an alcohol compound, a mercaptan compound, an acid amide compound, an imide compound, an amine compound, an imidazole compound, and a free isocyanate group of the above polyisocyanate compound. compounds, urea-based compounds, carbamic acid-based compounds, imine-based compounds, and other blocking agents.

The cross-linking agent (D) can be used alone or in combination of two or more.

In the coating composition of the present invention, from the viewpoint of hydrophilicity and corrosion resistance of the resulting coating film, a hydrophilic resin (A), a sulfonic acid surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D) The total solid content of the hydrophilic resin (A) and the sulfonic acid surfactant (B) is 10 to 35% by mass, particularly 12 to 30% by mass, more particularly 15 to 28% by mass, relative to the total solid content of % by mass is preferred.

In addition, the contents of the components (A), (B), (C), and (D) are the hydrophilic resin (A), the sulfonic acid surfactant (B), and the hydrophobic resin. The hydrophilic resin (A) is 5 to 25% by mass, particularly 7 to 20% by mass, more particularly 9 to 15% by mass, as the total solid content of each component relative to the total solid content of (C) and the crosslinking agent (D). 5 to 15% by mass, particularly 7 to 13% by mass, more particularly 9 to 11% by mass, of the sulfonic acid surfactant (B), and 20 to 60% by mass, particularly 25% by mass of the hydrophobic resin (C). to 55% by mass, more particularly 30 to 50% by mass, and the cross-linking agent (D) is 20 to 60% by mass, particularly 25 to 55% by mass, more particularly 30 to 50% by mass. It is preferable from the viewpoint of hydrophilicity, corrosion resistance and water resistance.

Further, the total solid content of the hydrophobic resin (C) is 25 to 65% by mass, particularly 30 to 60% by mass, more particularly 35% by mass, relative to the total solid content of the hydrophobic resin (C) and the cross-linking agent (D). From the viewpoint of the hydrophilicity and corrosion resistance of the coating film obtained, it is preferable that the amount is up to 55% by mass.

Other Components The coating composition of the present invention may optionally contain other components such as pigments, antirust agents, surfactants (excluding sulfonic acid-based surfactants (B)), rheology control agents, and surface conditioners. Ingredients normally used in paints, such as agents, ionic liquids, antifoaming agents and film-forming aids, can be appropriately contained, and water or a suitable organic solvent can be used as a diluting solvent.

Examples of pigments include coloring pigments, extender pigments, antirust pigments, and the like.

Examples of coloring pigments include titanium dioxide, red iron oxide, aluminum paste, azo pigments, and phthalocyanine pigments.

Examples of extender pigments include talc, silica, calcium carbonate, barium sulfate, zinc oxide (zinc oxide), and the like.

From the viewpoint of preventing environmental pollution, the antirust pigment preferably does not contain harmful metals such as lead and chromium. Phosphate compounds such as magnesium, and molybdate compounds such as calcium molybdate and zinc molybdate can be used. These pigments can be used alone or in combination of two or more.

Examples of rust preventives include organic phosphoric acids such as phytic acid and phosphinic acid, metal salts of biphosphate, nitrites, tannic acid, gallic acid, ascorbic acid and salts thereof.

The coating composition of the present invention comprises, for example, a hydrophilic resin (A), a sulfonic acid surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D), and if necessary, other components. It can be prepared by dissolving or dispersing in a medium.

The coating composition of the present invention preferably contains 80 to 97 mass %, preferably 85 to 95 mass % of water in the total solvent in the coating.

In addition to water, the entire medium may further contain an organic solvent, a neutralizing agent, and the like.

The coating composition of the present invention can be applied to various substrates that require hydrophilic surface treatment. Examples of substrates include metals, various plastics and their films, glass, paper, and wood. can be mentioned.

Examples of the metal base material include galvanized steel sheets, aluminum-galvanized steel sheets, aluminum sheets, aluminum alloy sheets, electromagnetic steel sheets, copper sheets, stainless steel sheets, etc., which are used for applications such as automobiles, home appliances, and building materials. can.

Examples of the plastic base material include, for example, acrylonitrile-butadiene-styrene resin (ABS resin) and polycarbonate resin, which are generally used in plastic molded products such as mobile phones, home appliances, automobile interior and exterior materials, and OA equipment. (PC resin), ABS/PC resin, polystyrene resin (PS resin), polymethyl methacrylate resin (PMMA resin), acrylic resin, polypropylene resin, polyethylene resin, and the like.

Examples of the plastic film substrate include polyethylene terephthalate film, polyester film, polyethylene film, polypropylene film, TAC (triacetylcellulose) film, polycarbonate film, and polyvinyl chloride film.

Construction materials such as exterior walls and roofs; Civil engineering materials such as guardrails, soundproof walls and drains; Household appliances; Aluminum fins; Industrial machinery; Anti-fog materials such as sheets and anti-fog glass; mirrors; medical instruments; and surface coating of various articles such as substrates such as sheets, coils or molded articles.

In particular, it can be suitably used for light metal materials such as aluminum and its alloy materials, molded products thereof, and vehicles, building materials, equipment, etc. using the molded products as parts.

The substrate and the article to be coated may have their surfaces degreased and, if necessary, subjected to a chemical conversion treatment. From the viewpoint of adhesion, corrosion resistance, etc., it is preferable that the surface is chemically treated. Examples of chemical conversion treatments include phosphate treatment, zirconium treatment, and chromate treatment.

Moreover, the base material and the article to be coated may be those having a primer coating film formed thereon.

Examples of the primer coating composition used for forming the primer coating film include acrylic resins, epoxy resins, acrylic-modified epoxy resins, urethane resins, polyester resins, polyoxyalkylene resins, ethylene/unsaturated carboxylic acid copolymers, A primer coating composition using ethylene ionomer resin, vinyl chloride resin or the like as a base resin can be mentioned. The primer coating composition may be either a water-based coating or an organic solvent-based coating. Further, the primer coating composition may be an inorganic compound-based primer coating composition.

The primer coating composition can be applied by a method known per se, such as dip coating, shower coating, spray coating, roll coating, electrophoretic coating, etc. The dry film thickness is usually 0.2 to 20 μm, preferably 0.2 to 20 μm. is applied so as to have a thickness of 0.5 to 10 μm, and a primer coating film is formed by setting at room temperature or baking and drying.

Baking and drying of the above-mentioned primer coating film is usually carried out under the conditions of a maximum material reaching temperature of about 80 to about 250° C., preferably 120 to 240° C., and a baking time of 6 seconds to about 30 minutes, preferably 8 seconds to 10 minutes. done below.

The coating composition of the present invention can be applied by a method known per se, such as dip coating, shower coating, spray coating, roll coater coating, curtain coater coating, flow coater coating, electrophoretic coating (electrodeposition coating), and the like. Among them, spray coating or roll coater coating is preferable.

The film thickness can be appropriately set according to the object to be coated, the required coating film performance, and the like. Usually, it is coated so that the cured film thickness is 0.2 to 20 μm, preferably 0.4 to 18 μm, more preferably 0.6 to 15 μm, and the hydrophilic coating is formed by setting at room temperature or baking and drying. can be formed.

For the baking drying of the hydrophilic coating film (curing of the coating composition of the present invention), the curing conditions can be appropriately selected depending on the composition. The conditions are 100 to 240° C. and a baking time of 6 seconds to about 20 minutes, preferably 8 seconds to 15 minutes.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. Here, "parts" and "%" mean "mass parts" and "mass%" respectively. Parts by mass of raw materials in the following Production Examples, Examples and Comparative Examples represent parts by mass of the solid content (or active ingredient) of the raw materials.

Raw materials in the table are as follows.

Hydrophilic resin (A)
(Note 1) Polyacrylamide resin No. 1: Weight average molecular weight about 80000, hydrophilic group content about 14000 mmol/kg, total amount of acrylamide 90% mass or more (Note 2) Polyacrylamide resin No. 2: Weight average molecular weight about 40000, hydrophilic group content about 14000 mmol/kg, total amount of acrylamide 90% mass or more (Note 3) Polyacrylamide resin No. 3: Weight average molecular weight about 8000, hydrophilic group content about 14000 mmol/kg, total amount of acrylamide 90% mass or more (Note 4) Haricoat 1057: manufactured by Harima Chemicals, trade name, weight average molecular weight about 300000, nonionic polyacrylamide Resin, hydrophilic group content about 14000 mmol/kg, total amount of acrylamide 90% mass or more (Note 5) Hydrophilic acrylic resin No. 1: As follows, synthesized acrylic resin emulsion, hydrophilic group content of about 14600 mmol / kg, total amount of acrylamide 40% by mass, total amount of amide group-containing monomers 52% by mass
25 parts of isopropyl alcohol and 250 parts of deionized water were placed in a four-necked flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet, and the temperature was raised to 80°C. Next, a mixture of the following monomer, solvent and initiator was added dropwise into the flask over 4 hours, and after the completion of the dropwise addition, the temperature was maintained at 80° C. for an additional 2 hours. A dispersion of 1 was obtained. Hydrophilic acrylic resin No. The weight average molecular weight of 1 was 250,000, the average particle diameter of the dispersion liquid was 50 nm, the resin hydroxyl value was 80 mgKOH/g, and the resin acid value was 168 mgKOH/g.

Hydrophilic acrylic resin No. Dispersion of 1 Blemmer PME-400 (*) 20 parts Acrylamide 40 parts N-methylolacrylamide 10 parts Acrylic acid 21 parts 2-Hydroxyethyl methacrylate 7 parts Methylenebisacrylamide 2 parts Ammonium persulfate 1.5 parts Deionized water 290 parts BLEMMER PME-400 (*): manufactured by NOF Corporation, trade name, hydrophilic monomer having a polymerizable double bond and a polyoxyalkylene chain, (CH ₂ CH ₂ O) repeating unit number n = 9 (average value)
(Note 6) Hydrophilic acrylic resin No. 2: Synthesized acrylic resin emulsion having a hydrophilic group content of about 16400 mmol/kg, a total amount of acrylamide of 20% by mass, and a total amount of amide group-containing monomers of 36% by mass as follows.
25 parts of isopropyl alcohol and 250 parts of deionized water were placed in a four-necked flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet, and the temperature was raised to 80°C. Next, a mixture of the following monomer, solvent and initiator was added dropwise into the flask over 4 hours, and after the completion of the dropwise addition, the temperature was maintained at 80° C. for an additional 2 hours. A dispersion of 2 was obtained. Hydrophilic acrylic resin No. The weight average molecular weight of 2 was 250000, the average particle size of the dispersion liquid was 55 nm, the resin hydroxyl value was 87 mgKOH/g, and the resin acid value was 164 mgKOH/g.

Hydrophilic acrylic resin No. Dispersion of 2 BLEMMER PME-400 (*) 40 parts Acrylamide 20 parts N-methylolacrylamide 15 parts Acrylic acid 21 parts 2-Hydroxyethyl methacrylate 3 parts Methylenebisacrylamide 1 part Ammonium persulfate 1.5 parts Deionized water 290 parts (Note 7) Cellogen F-7A: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name, weight average molecular weight of about 30000, carboxymethylcellulose sodium compound, hydrophilic group content of about 18500 mmol/kg
(Note 8) PEG-20000: manufactured by Sanyo Chemical Industries, Ltd., trade name, weight average molecular weight of about 20000, polyoxyalkylene compound, hydrophilic group content of about 23000 mmol/kg
(Note 9) JE-04: manufactured by Nippon Vinyl Poval Co., Ltd., trade name, weight average molecular weight of about 17000, polyvinyl alcohol compound, hydrophilic group content of about 7700 mmol/kg
Sulfonic acid surfactant (B)
(Note 10) Newcol 290-A: Nippon Emulsifier Co., Ltd., trade name, sulfosuccinic acid-based anionic surfactant (Note 11) Newcol 271-A: Nippon Emulsifier Co., Ltd., trade name, alkyldiphenyl ether disulfonic acid type of anionic surfactants
(Note 12) Levenol WX: An anionic surfactant based on sodium polyoxyethylene alkyl ether sulfate, manufactured by Kao Corporation
(Note 13) Plysurf M208F: Daiichi Kogyo Seiyaku Co., Ltd., phosphate ester type anionic surfactant (Note 14) New Cole 2308: Nippon Nyukazai Co., Ltd., trade name, polyoxyethylene alkyl ether, nonionic surfactant , HLB=13.2
(Note 15) Amphitol 20AB: Kao Corp., amphoteric surfactant based on lauramidopropyl betaine Note that (Note 13) to (Note 15) are not sulfonic acid surfactants, but for comparative examples.

Hydrophobic resin (C)
(Note 16) Hydrophobic acrylic resin No. 1: Acrylic resin emulsion (St/MMA/2HEA/HEMA/Aac: 10/60/25/4/1), resin hydroxyl value 138 mgKOH/g, resin acid value 8 mgKOH/g , hydrophilic group content about 2600 mmol / kg
(Note 17) Polyurethane resin No. 1: A urethane resin emulsion synthesized as follows, with a hydrophilic group content of about 300 mmol/kg
In a reaction vessel, 115.5 parts of polybutylene adipate with a number average molecular weight of 2000, 115.5 parts of polycaprolactone diol with a number average molecular weight of 2000, 23.2 parts of dimethylolpropionic acid, 14.5 parts of 1,4-butanediol and 120.1 parts of isophorone diisocyanate was charged and reacted at 85° C. for 7 hours in a nitrogen stream with stirring to obtain a prepolymer having an NCO content of 4.0%.

Next, the prepolymer was cooled to 50° C., 165 parts of acetone was added and dissolved uniformly, 15.7 parts of triethylamine was added with stirring, and 600 parts of deionized water was added while maintaining the temperature at 50° C. or less to obtain After holding the aqueous dispersion at 50° C. for 2 hours to complete the water elongation reaction, acetone is distilled off under reduced pressure at 70° C. or lower, and the pH is adjusted to 8.0 with triethylamine and deionized water. An emulsion of urethane resin No. 1 having a value of 17 mgKOH/g, a solid content of 30% by mass and an average particle size of 150 nm was obtained.

(Note 18) Epoxy resin No. 1: Acryl-modified epoxy resin synthesized as follows, hydrophilic group content of about 2700 mmol/kg
Carboxyl group-containing acrylic resin No. Preparation of solution 1 850 parts of n-butanol is heated to 100 ° C. under a nitrogen stream, and a monomer mixture and a polymerization initiator "450 parts of methacrylic acid, 450 parts of styrene, 100 parts of ethyl acrylate, t-butylperoxy-2 -Ethylhexanoate 40 parts" was added dropwise over 3 hours, and after the dropwise addition, the mixture was aged for 1 hour. Then, a mixed solution of 10 parts of t-butylperoxy-2-ethylhexanoate and 100 parts of n-butanol was added dropwise over 30 minutes, and after the dropwise addition, the mixture was aged for 2 hours.

Next, 933 parts of n-butanol and 400 parts of ethylene glycol monobutyl ether were added to give a carboxyl group-containing acrylic resin No. 3 having a solid content of about 30%. 1 solution was obtained. The resulting resin had a resin acid value of 300 mgKOH/g and a weight average molecular weight of about 17,000.

Production of water dispersion of acrylic-modified epoxy resin In a reaction vessel, jER828EL (manufactured by Mitsubishi Chemical, epoxy resin, epoxy equivalent weight: about 190, number average molecular weight: about 380) 513 parts, bisphenol A 287 parts, tetramethylammonium chloride 0.3 parts And 89 parts of methyl isobutyl ketone were charged, heated to 140° C. under a nitrogen stream, and reacted for about 4 hours to obtain an epoxy resin solution. The resulting epoxy resin had an epoxy equivalent weight of 3,700 and a number average molecular weight of about 17,000.

Next, the obtained epoxy resin solution was added with the carboxyl group-containing acrylic resin No. 1 having a solid content of about 30% obtained above. 667 parts of solution No. 1 was charged and heated to 90° C. to dissolve uniformly. At the same temperature, 40 parts of deionized water was added dropwise over 30 minutes, then 30 parts of dimethylethanolamine was added and stirred for 1 hour. and reacted.

Further, 2380 parts of deionized water was added over 1 hour to obtain epoxy resin No. 2, which is an acrylic-modified epoxy resin having a solid content of about 25%. A water dispersion of 1 was obtained. The resulting resin had a number average molecular weight of about 22,000 and a resin acid value of 48 mgKOH/g. The average particle size of the dispersion was 190 nm.

(Note 19) jER W2821R70: manufactured by Mitsubishi Chemical Corporation, trade name, bisphenol A type epoxy resin emulsion, solid content of about 70%, epoxy equivalent of about 230, hydrophilic group content of about 3500 mmol/kg
Crosslinking agent (D)
(Note 20) Cymel 327: manufactured by Daicel Allnex Co., Ltd., trade name, imino group type methylated melamine resin, solid content 90%
(Note 21) Cymel 350: manufactured by Daicel Allnex Co., Ltd., trade name, completely alkyl-type methylated melamine resin, solid content 100%
(Note 22) Cymel 303: manufactured by Daicel Allnex Co., Ltd., trade name, completely alkyl-type methylated melamine resin, solid content 100%
(Note 23) Nikalac MX-290: manufactured by Sanwa Chemical Co., Ltd., trade name, methylated urea resin (Note 24) Shounol BKM-262: manufactured by Showa Polymer Co., Ltd., trade name, phenolic resin
[Manufacture of paint composition]
Example 1 Coating composition no. Production of polyacrylamide resin No. 1. 1 (note 1) 5 parts (solid content), Newcol 290-A (note 10) 5 parts (solid content), polyurethane resin No. 1 (note 17) 55 parts (solid content) and CYMEL 327 (note 20) 35 parts (solid content) were mixed and stirred, and adjusted with deionized water to give a coating composition No. 1 (note 17) having a solid content of 10%. got 1.

Examples 2 to 37 and Comparative Examples 1 to 12 Coating composition no. 2 to No. Manufacture of No. 49 Each coating composition No. 49 having a solid content of 10% was prepared in the same manner as in Example 1 except that the formulations shown in Tables 1 to 4 were used. 2 to No. 49 was obtained.

Incidentally, the coating composition No. 38 to No. 49 is for comparative example.

[Preparation of coated plate for test]
Preparation of test plate (1) An aluminum plate (A1050, plate thickness 0.1 mm) was treated with an aqueous solution of 2% concentration in which an alkaline degreasing agent (manufactured by Nippon CB Chemical Co., Ltd., trade name “Chemicleaner 561B”) was dissolved. Degreasing was performed, and then zirconium chemical conversion treatment was performed. Next, each coating composition was applied so that the film thickness of the dry coating film was 0.7 μm, and baked for 10 seconds under the condition that the maximum material reaching temperature was 220° C. to obtain each test panel (1).

Preparation of test plate (2) Each coating composition was applied to a steel plate coated with an electrodeposition coating film so that the thickness of the dry coating film was 10 μm, and baked at 140 ° C. for 10 minutes to prepare each test plate. (2) was obtained.

Each test was conducted according to the following test method for each test coated plate obtained above. The test results are also shown in Tables 1-4.

water resistant:
Using each test plate (1), three layers of gauze impregnated with water were rubbed, and the number of reciprocations until the substrate was exposed was evaluated according to the following criteria.
⊚ indicates no problem at 30 times or more.
○ is 20 times or more and less than 30 times, and Δ, which is within the practical range, is 10 times or more and less than 20 times, and is somewhat problematic. × is less than 10 times, which is significantly insufficient. .

Hydrophilicity:
10 μL of water is dropped on each test plate (1) and each test plate (2) at a room temperature of 20° C. on the coated surface, and the contact angle between the water droplet and the coated surface is measured using “Automatic Contact” manufactured by Kyowa Interface Science Co., Ltd. Hydrophilicity was evaluated by measuring with a goniometer DM-501 (trade name).
⊚ indicates a contact angle of less than 15° and a remarkably good level of hydrophilicity sustainability. ○ indicates a contact angle of 15° or more and less than 30° and a good level of hydrophilicity retention.
Δ indicates that the contact angle is 30° or more and less than 50°, and the durability of hydrophilicity is insufficient. × indicates that the contact angle is 50° or more, and the durability of hydrophilicity is significantly insufficient.
Hydrophilic persistence:
Each test plate (1) and each test plate (2) were immersed in running tap water (flow rate: 15 kg/h per 1 m ² of coated plate on the coated surface) for 72 hours, dried at 80°C for 5 minutes, 10 μL of water is dropped on the coated surface at room temperature of 20° C., and the contact angle between the water droplet and the coated surface is measured using an “automatic contact angle meter DM-501” (trade name) manufactured by Kyowa Interface Science Co., Ltd. By doing, the hydrophilicity persistence was evaluated. ◎ and 〇 are the pass levels.
⊚ indicates a contact angle of less than 15° and a remarkably good level of hydrophilicity sustainability. ○ indicates a contact angle of 15° or more and less than 30° and a good level of hydrophilicity retention.
Δ indicates that the contact angle is 30° or more and less than 50°, and the durability of hydrophilicity is insufficient. × indicates that the contact angle is 50° or more, and the durability of hydrophilicity is significantly insufficient.
Hydrophilic persistence after heat cycle test:
Using each test plate (1), ``Immersion for 17 hours in running tap water (flow rate is 15 kg/hour per ^1m2 of coated plate on the coated surface) - drying for 7 hours at 80°C'' is one cycle, and 5 cycle repeated. After that, 10 μL of water was dropped on the coated surface at room temperature of 20° C., and the contact angle between the water droplet and the coated surface was measured using “Automatic Contact Angle Meter DM-501” (trade name) manufactured by Kyowa Interface Science Co., Ltd. The heat cycle property was evaluated by measuring using ◎ and 〇 are the pass levels.
⊚ indicates a contact angle of less than 15° and a remarkably good level of hydrophilicity sustainability. ○ indicates a contact angle of 15° or more and less than 30° and a good level of hydrophilicity retention.
Δ indicates that the contact angle is 30° or more and less than 50°, and the durability of hydrophilicity is insufficient. × indicates that the contact angle is 50° or more, and the durability of hydrophilicity is significantly insufficient.
Water elution resistance:
Using each test plate (1), the coating film weight loss ratio (%) was determined according to the following steps 1 to 3, and evaluated according to the following criteria.

Step 1: Measure the mass of the aluminum plate...A
Step 2: Measure the mass of the film-coated plate, which is an aluminum plate coated with a hydrophilic treatment agent B
Step 3: Measure the mass of the coated board after immersing the coated board in deionized water for 72 hours and drying at 80°C for 30 minutes...C
Paint film weight loss ratio (%) = {[mass of B - mass of C] / [mass of B - mass of A]} x 100
◎ indicates that the coating weight loss ratio (%) is 5% or less ○ indicates that the coating weight loss ratio (%) exceeds 5% and is 10% or less △ indicates that the coating weight loss ratio (%) is Exceeding 10% and 15% or less × indicates that the coating film weight loss rate (%) exceeds 15%
Corrosion resistance:
Using each test plate (1), a test was conducted according to JIS-Z-2371 salt spray test method. The test time was set to 500 hours, and evaluation was made according to the following criteria.
◎: No white rust or blisters occurred on the painted surface ○: White rust or blisters occurred on part of the painted surface △: A little white rust or blisters occurred on the entire surface ×: White rust or blisters on the entire surface occurred significantly in

Corrosion and odor resistance:
Each test plate (1) was subjected to a corrosion resistance test for 500 hours according to the JIS-Z-2371 salt spray test method, and then exhaled to evaluate the corrosion odor level of aluminum according to the following criteria.
◎: No odor 〇: Slight odor △: Smell ×: Significant odor
Hot water resistance:
Each test plate (2) was immersed in hot water at 80° C. for 2 hours, and then the appearance was evaluated according to the following criteria.
⊚: No change in coating surface appearance ◯: Slight whitening of coating surface △: Whitening of coating surface ×: Significant whitening of coating surface.

It is possible to provide a coating composition that can provide a coating film that is excellent in hydrophilicity (durability), corrosion resistance, and water resistance on the surface of various materials such as substrates.

Claims (5)

Containing a hydrophilic resin (A), a sulfonic acid surfactant (B), a hydrophobic resin (C) and a cross-linking agent (D),
With respect to the total solid content of the hydrophilic resin (A), the sulfonic acid surfactant (B), the hydrophobic resin (C) and the cross-linking agent (D),
A coating composition in which the hydrophilic resin (A) and the sulfonic acid-based surfactant (B) have a total solid content of 10 to 35% by mass. The hydrophilic resin (A) contains at least one hydrophilic acrylic polymer in which the total amount of amide group-containing monomers is 50% by mass or more relative to the total amount of monomer components constituting the polyacrylamide resin or polymer. Item 1. The coating composition according to item 1. 3. The coating composition according to claim 1, wherein the hydrophilic resin (A) has a weight average molecular weight of 5,000 to 350,000. The coating composition according to any one of claims 1 to 3, wherein the hydrophobic resin (C) contains at least one selected from acrylic resin (C1), polyurethane resin (C2), and epoxy resin (C3). . With respect to the total solid content of the hydrophilic resin (A), the sulfonic acid surfactant (B), the hydrophobic resin (C) and the cross-linking agent (D),
The total solid content of each component is hydrophilic resin (A) 5 to 25% by mass, sulfonic acid surfactant (B) 5 to 15% by mass, hydrophobic resin (C) 20 to 60% by mass, cross-linking agent (D) ) The coating composition according to any one of claims 1 to 4, which is 20 to 60% by mass.