JP6870202B2 - Aqueous dressing - Google Patents

Description

The present invention relates to a water-based coating material and a coating material thereof.

In recent years, in the field of paints, the conversion from organic solvent-based paints to water-based paints has been attempted from the viewpoints of environmental protection and safety and health. However, water-based paints have problems such as storage stability, appearance, water resistance, and substrate adhesion, which are lower than those of organic solvent-based paints. Development is in progress.
For example, Patent Document 1 discloses that an aqueous coating material containing a blocked isocyanate compound with a self-dispersible acrylic aromatic epoxy resin has excellent heat resistance. Patent Document 2 discloses that an aqueous coating material containing an epoxy resin, an acrylic copolymer, and an aqueous amine curing agent is excellent in corrosion resistance, dripping resistance, and coating workability.

Japanese Unexamined Patent Publication No. 2003-12758 International Publication No. 12/033226

However, the appearance, water resistance, moisture resistance, and coating film hardness of the coating film obtained from any of the water-based coating materials may be insufficient.
An object of the present invention is to provide a water-based coating material capable of forming a coating film having excellent appearance, water resistance, moisture resistance, and coating film hardness.

The present invention is an aqueous coating material obtained by a phase inversion emulsification step of a solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III), and has a mass of 60 mass of the organic solvent (I). % or more solubility parameter (SP value) by the Fedors method is an organic solvent 9.00 (cal ^/ cm ^{3) 1/2} or less, there in polymers in which the polymer (II) has a hydroxyl group and a carboxyl group The step (1) of obtaining a dispersion liquid containing the polymer (P) obtained by polymerizing the radically polymerizable monomer (A) in the presence of the α-methylstyrene dimer in the organic solvent (I). And the polymer (Q) obtained by polymerizing the radically polymerizable monomer (B) and polymerizing the radically polymerizable monomer (B) in the dispersion liquid containing the polymer (P). It is an aqueous coating material produced by a method including the step (2) of obtaining a dispersion liquid.

The present invention is a method for producing an aqueous coating material, which comprises a step of phase inversion emulsification of a solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III). solubility parameter above 60% by weight by the Fedors method of (SP value) is an organic solvent 9.00 (cal ^/ cm ^{3) 1/2} or less, weight to the polymer (II) has a hydroxyl group and a carboxyl group A step of obtaining a dispersion liquid containing a polymer (P) obtained by polymerizing a radically polymerizable monomer (A) in the presence of an α-methylstyrene dimer in the organic solvent (I). A polymer (Q) obtained by polymerizing a radically polymerizable monomer (B) in a dispersion containing (1) and the polymer (P) and polymerizing the radically polymerizable monomer (B). ) Is a method for producing an aqueous coating material, which is produced by a method including the step (2) for obtaining a dispersion liquid containing the above.

When the water-based coating material of the present invention is used, a coating film having excellent appearance, water resistance, moisture resistance, and coating film hardness can be obtained.

The aqueous coating material of the present invention (hereinafter referred to as the present aqueous coating material) contains an organic solvent (I), a polymer (II), and a curing agent (III).

[Organic solvent (I)]
Organic solvent (I) preferably includes solubility parameter according to Fedors method (SP value) of 11.00 (cal ^/ cm ^{3) 1/2} to the organic solvent is less than 60% by mass or more. ^{The higher the proportion of the organic solvent having an SP value of 11.00 (cal / cm 3} ) ^1/2 or less with respect to the total amount of the organic solvent (I), the more the curing agent (III) is contained in the polymer (II). The appearance, water resistance, moisture resistance, and coating film hardness of the obtained coating film tend to be improved. The SP value of the organic solvent in the present invention is a value calculated by the Fedors method (Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)). The SP value δ can be calculated using the following formula (1).
δ = (E / V) ^1/2 (1)
(E in the above formula represents aggregation energy (cal / mol), and V represents molar volume (cm ³ / mol).)

The SP value of the organic solvent, which accounts for 60% by mass or more of the organic solvent (I), ^{is more preferably 10.00 (cal / cm 3} ) ^1/2 or less, and 9.00 (cal / cm ³ ) ^1/2. It is more preferably less than or equal to 8.50 (cal / cm ³ ) ^1/2 or less.
The content of the organic solvent having an SP value of 11.00 (cal / cm ³ ) ^1/2 or less in the organic solvent (I) is more preferably 70% by mass or more, further preferably 80% by mass or more, and 90% by mass or more. Mass% or more is particularly preferable.

Further, the organic solvent (I) can contain 60% by mass or more of an organic solvent having a solubility in water at 20 ° C. of 1 g / 100 g or more, more preferably 3 g / 100 g or more, still more preferably 9 g / 100 g or more. It is preferable because the viscosity of the water-based coating material to be obtained can be kept low. The content of the organic solvent having a solubility in water at 20 ° C. of 1 g / 100 g or more is more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more.

Preferred organic solvents include, for example, propylene glycol dimethyl ether (SP value: 7.53, solubility in water at 20 ° C.: 44 g / 100 g), ethylene glycol dimethyl ether (SP value: 7.63, solubility in water at 20 ° C.). : ∞ g / 100 g), dipropylene glycol dimethyl ether (SP value: 7.88, solubility in water at 20 ° C.: 53 g / 100 g), tripropylene glycol dimethyl ether (SP value: 8.07, in water at 20 ° C.) Solubility: 24 g / 100 g), Diethylene glycol dimethyl ether (SP value: 8.10, Solubility in water at 20 ° C: ∞ g / 100 g), Diethylene glycol diethyl ether (SP value: 8.18, Solubility in water at 20 ° C: Solubility: ∞ g / 100 g), triethylene glycol dimethyl ether (SP value: 8.37, solubility in water at 20 ° C.: ∞ g / 100 g), dipropylene glycol monomethyl ether acetate (SP value: 8.71, water at 20 ° C.) Solubility in water: 19 g / 100 g), propylene glycol monomethyl ether acetate (SP value: 8.73, solubility in water at 20 ° C.: 1.6 g / 100 g), diethylene glycol monoethyl ether acetate (SP value: 9.00, Examples thereof include solubility in water at 20 ° C.: ∞ g / 100 g), propylene glycol diacetate (SP value: 9.60, solubility in water at 20 ° C.: 8 g / 100 g), and the like. These organic solvents may be used alone or in combination of two or more.

The content of the organic solvent (I) in this aqueous coating material is preferably 1 to 50 parts by mass, and 5 to 35 parts by mass with respect to 100 parts by mass of the polymer (II) from the viewpoint of storage stability, environmental protection, and safety and health. Parts by mass are more preferred.

[Polymer (II)]
Radically polymerizable monomer polymer (II) has a purpose of reacting with the later curing agent (III), from the viewpoint of encapsulated curing agent by the polymer (II) (III), a hydroxyl group Is preferable. Such a polymer (II) can be produced by (co) polymerizing a hydroxyl group-containing radically polymerizable monomer (a). Specific examples of the hydroxyl group-containing radically polymerizable monomer (a) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl. Examples thereof include (meth) acrylate, 1-methyl-4-hydroxybutyl (meth) acrylate, 1-methyl-4-hydroxypentyl (meth) acrylate, and allyl glycol. These can be used alone or in combination of two or more.

The amount of the hydroxyl group-containing radical polymerizable monomer (a) used is preferably 5 to 50% by mass, more preferably 7 to 45% by mass, based on the total amount of the monomers used in the production of the polymer (II). 10 to 40% by mass is more preferable. The larger the amount used, the more excellent the coating film obtained by the reaction with the curing agent is in water resistance, moisture resistance, coating film hardness and the like. Further, the smaller the amount, the better the appearance of the obtained coating film.

Further, from the viewpoint of encapsulation of the curing agent (III) by the polymer (II), the polymer (II) preferably has a carboxyl group. Such a polymer (II) can be produced by (co) polymerizing a carboxyl group-containing radically polymerizable monomer (b). Specific examples of the carboxyl group-containing radically polymerizable monomer (b) include methacrylic acid, acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, vinyl benzoic acid, maleic acid monobutyl ester, and itaconic acid. Examples thereof include monomethyl ester and itaconic acid butyl ester. These can be used alone or in combination of two or more.

The amount of the carboxyl group-containing radical polymerizable monomer (b) used is preferably 0.5 to 5% by mass, preferably 0.5 to 3% by mass, based on the total amount of the monomers used in the production of the polymer (II). % Is more preferable, and 0.5 to 2% by mass is further preferable. The larger the amount used, the better the storage stability of the water-based dressing, and the better the appearance of the obtained coating film. Further, the smaller the amount, the more excellent the water resistance and moisture resistance of the obtained coating film.

Examples of the radically polymerizable monomer (c) other than the monomers (a) and (b) that can be used in the production of the polymer (II) include methyl (meth) acrylate and ethyl (meth) acrylate. , N-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) ) Alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms such as acrylate; styrene derivatives such as styrene, vinyltoluene and α-methylstyrene; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; N-alkoxy substituted amides such as N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl acrylamide; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth). ) Acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, epoxy group-containing ethylenically unsaturated monomers such as allylglycidyl ether, dimethylaminoethyl (meth) Examples thereof include ethylenically unsaturated basic monomers such as acrylate and diethylaminoethyl (meth) acrylate. These can be used alone or in combination of two or more. Further, from the viewpoint of encapsulation of the curing agent (III) by the polymer (II), the radically polymerizable monomer (c) is preferably an epoxy group-containing ethylenically unsaturated monomer. The amount of the radically polymerizable monomer (c) used is preferably 0.01 to 1% by mass, preferably 0.01 to 0.5% by mass, based on the total amount of the monomers used in the production of the polymer (II). Is more preferable, and 0.01 to 0.2% by mass is more preferable.

α-Methylstyrene dimer α-methylstyrene dimer (2,4-diphenyl-4-methyl-1-pentene; hereinafter, sometimes referred to as “MSD”) is known as an add-square root chain transfer agent (2,4-diphenyl-4-methyl-1-pentene; Japanese Unexamined Patent Publication No. 7-2954). When a radically polymerizable monomer is polymerized in the presence of MSD, a polymer having an unsaturated group derived from MSD at the terminal is obtained. When a radically polymerizable monomer is polymerized in the presence of this polymer, a polymer in which a polymer chain composed of this monomer is grafted can be obtained. The polymer (II) produced by polymerizing in the presence of MSD can contain a larger amount of the curing agent (III), the aqueous coating material has excellent storage stability, and the obtained coating film has an appearance and water resistance. Has excellent properties and moisture resistance.
The amount of MSD used is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the total amount of the radically polymerizable monomers (a), (b) and (c) used in the production of the polymer (II). 0.5 to 10 parts by mass is more preferable, and 0.5 to 5 parts by mass is further preferable.

Polymerization Step The polymer (II) of the present invention can be produced by a known polymerization method such as a solution polymerization method, a massive polymerization method, an emulsion polymerization method, etc. Among them, a solution using an organic solvent (I) as a solvent. It is preferably produced by a polymerization method.
Further, the polymerization step of the polymer (II) preferably includes the following steps (1) and (2).

<Process (1)>
A step of obtaining a dispersion liquid containing a polymer (P) obtained by polymerizing a radically polymerizable monomer (A) in an organic solvent (I).

<Process (2)>
A step of polymerizing a radically polymerizable monomer (B) in a dispersion liquid containing the polymer (P) to obtain a dispersion liquid containing the polymer (Q).

The polymerization of step (1) is preferably carried out in the presence of MSD. The presence of MSD gives a polymer (P) having an unsaturated group derived from MSD at the end. When the polymerization of the step (2) is carried out using this polymer (P), the polymer (II) obtained by grafting the polymer (Q) onto the polymer (P) is obtained. This polymer (II) can contain a larger amount of the curing agent (III), and can further improve the storage stability, the appearance of the obtained coating film, the water resistance, and the moisture resistance.

Further, from the viewpoint of encapsulation of the curing agent (III) by the polymer (II), the radically polymerizable monomer (A) is a hydroxyl group-containing radically polymerizable monomer (a) and an epoxy group-containing ethylenically non-polymeric monomer. It contains a saturated monomer, and the radically polymerizable monomer (B) preferably contains a carboxyl group-containing radical monomer (b). When an epoxy group is introduced into the polymer (P) using an epoxy group-containing ethylenically unsaturated monomer, the carboxyl group-containing radical monomer (b) contained in the epoxy group and the radically polymerizable monomer (B) ) Reacts with the carboxyl group to obtain a polymer (II) obtained by grafting the polymer (Q) onto the polymer (P), and obtains storage stability and the appearance, water resistance, and moisture resistance of the obtained coating film. It can be further improved.

The reaction temperature at the time of polymerization in the step (1) is preferably in the range of 110 ° C. to 200 ° C. from the viewpoint of the reaction efficiency of MSD and the like. The polymerization time is usually preferably 1 hour to 10 hours, more preferably 1 hour to 6 hours.

The weight average molecular weight polymer (II) preferably has a weight average molecular weight of 3,000 to 100,000, more preferably 3,000 to 50,000, and even more preferably 5,000 to 20,000. The larger the weight average molecular weight, the better the obtained coating film has various durability such as water resistance, moisture resistance, weather resistance, and solvent resistance, and the smaller the weight average molecular weight, the better the dispersibility in water, and the obtained coating film has excellent appearance.

In the present specification, the weight average molecular weight of the polymer (II) means the weight average molecular weight measured under the following conditions by using the tetrahydrofuran-soluble component as a polystyrene-equivalent value by the GPC method.
Measuring device: High-speed GPC device HLC-8320 manufactured by Tosoh Corporation
Column: Made by Tosoh Corporation, TSKgelSuper HZM-M, HZM-M, HZ2000
Oven temperature: 40 ° C
Eluent: tetrahydrofuran Sample concentration: 0.3% by weight
Flow velocity: 0.35 mL / min Injection volume: 10 μL

As the initiator , those generally used for radical polymerization can be used, for example, azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'. Oils such as -azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile Soluble azo compounds; 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis {2-methyl-N -[2- (1-Hydroxyethyl)] propionamide}, 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2'-azobis [2 -(5-Methyl-2-imidazolin-2-yl) propane] and its salts, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] and its salts, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidine-2-yl) propane] and its salts, 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane) and its salts, 2 , 2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} and its salts, 2,2'-azobis (2-methylpropionamidine) and its salts, 2 , 2'-Azobisisobuty [N- (2-carboxyethyl) -2-methylpropionamidine] and water-soluble azo compounds such as salts thereof; benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butyl Examples thereof include organic peroxides such as peroxy-2-ethylhexanoate and t-butylperoxyisobutyrate, and persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate. These can be used alone or in combination of two or more.

Other chain transfer agents When adjusting the molecular weight, mercaptans other than MSD such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan, etc. Known chain transfer agents such as halogen compounds such as carbon tetrachloride and ethylene bromide can also be used, and these can be used alone or in combination of two or more.

[Curing agent (III)]
The curing agent (III) of the present invention is a compound having two or more functional groups capable of reacting with the functional group of the polymer (II) in the molecule, and examples of such a combination of functional groups include an epoxy group. Examples thereof include -amino group, epoxy group-acid group, hydroxyl group-isocyanate group, hydroxyl group-methylol group, carboxyl group-metal ion, carboxyl group-carbodiimide group, carboxyl group-oxazoline group and the like. From the viewpoint of encapsulation of the curing agent (III) by the polymer (II), the curing agent (III) is preferably a block polyisocyanate curing agent and / or a melamine resin curing agent.

The blocked polyisocyanate curing agent is obtained by blocking the isocyanate group of the polyisocyanate compound with a blocking agent, and the blocking agent is dissociated by heating to regenerate the free isocyanate group, which can easily react with the hydroxyl group.

Examples of the polyisocyanate compound include aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimerate diisocyanate, and lysine diisocyanate; burette-type adducts and isocyanurate ring adducts of these diisocyanate compounds; isophorone diisocyanates, 4,4'-Methylenebis (cyclohexylisocyanate), methylcyclohexane-2,4- (or -2,6-) diisocyanate, 1,3- (or 1,4-) di (isocyanatomethyl) cyclohexane, 1,4 Alicyclic diisocyanate compounds such as −cyclohexanediisocyanate, 1,3-cyclopentanediisocyanate, 1,2-cyclohexanediisocyanate; bullet-type adducts of these diisocyanate compounds, isocyanurate ring adducts; xylylene diisocyanates, Metaxylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalenediisocyanate, 1,4-naphthalenediocyanate, 4,4'-toluidin diisocyanate, 4 , 4'-diphenyl ether diisocyanate, (m- or p-) phenylenediisocyanate, 4,4'-biphenylenediocyanate, 3,3'-dimethyl-4,4'-biphenylenediocyanate, bis (4-isocyanatophenyl) sulfate, Aromatic diisocyanate compounds such as isopropyridenebis (4-phenylisocyanate); bullet-type adducts of these diisocyanate compounds, isocyanurate ring adducts; triphenylmethane-4,4', 4''-tri In one molecule such as isocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4'-dimethyldiphenylmethane-2,2', 5,5'-tetraisocyanate, etc. Polyisocyanate compounds having 3 or more isocyanate groups; burette-type adducts, isocyanurate ring adducts of these polyisocyanate compounds; ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylol propionic acid, polyalkylene Isocyanate on the hydroxyl group of polyols such as glycol, trimethylpropane, and hexanetriol Urethane adducts formed by reacting polyisocyanate compounds in an excess amount of groups; bullet-type adducts of these urethanized adducts, isocyanurate ring adducts, and the like can be mentioned. These can be used alone or in combination of two or more.
Examples of the blocking agent include phenolic compounds such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol and methyl hydroxybenzoate; ε-caprolactam, δ-valerolactam, Oxime compounds such as γ-butyrolactam and β-propiolactam; aliphatic alcohol compounds such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol and lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene Ether compounds such as glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid ester compounds such as methyl glycolate, ethyl glycolate, and butyl glycolate. Lactic acid esters such as lactic acid, methyl lactate, ethyl lactate, butyl lactate; alcoholic substances such as methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acet Oxime compounds such as oxime, methylethylketooxime, diacetylmonooxime, benzophenone oxime, cyclohexaneoxime; dimethyl malonate, diethyl malate, diisopropyl malate, din-butyl malate, diethyl methylmalonate, benzylmethyl malonate, malon Maronic acid dialkyl ester such as diphenyl acid, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, n-propyl acetoacetate, benzyl acetoacetate, acetoacetate such as phenylacetate, active methylene compound such as acetylacetone; butyl mercaptan , T-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol and other mercaptan compounds; Acids such as acid amides and benzamides Amid-based; imide-based compounds such as succinide imide, phthalate imide, and maleate imide; amine-based compounds such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine. Imidazole compounds such as imidazole and 2-ethylimidazole; pyrazole compounds such as 3,5-dimethylpyrazole; urea compounds such as urea, thiourea, ethyleneurea, ethylenethiourea and diphenylurea; phenyl N-phenylcarbamate Carbamate-based compounds such as ethyleneimine, imine-based compounds such as propyleneimine; sulfite-based compounds such as sodium bisulfite and potassium bisulfite. These can be used alone or in combination of two or more. For example, commercially available products such as the Duranate series (trade name, manufactured by Asahi Kasei Corporation) such as "SBN-70D", "17B-60P", "MF-B60B", and "17B-60P" can be used. .. In particular, a solvent-based or solvent-free hydrophobic block block polyisocyanate curing agent is preferable from the viewpoint of encapsulation of the curing agent (III) by the polymer (II).

Examples of the melamine resin curing agent include a resin obtained by further reacting melamine and formaldehyde with water and / or alcohol, if necessary. Specific examples thereof include di, tree, tetra, penta, hexamethylolmelamine and alkyl ethers thereof. These can be used alone or in combination of two or more. For example, "Symel 202", "Symel 232", "Symel 254", "Symel 325" and other Cymel series (trade name, manufactured by Nippon Cytec Industries, Ltd.), "Uban 20SB", "Uban 28-60". You can use commercial products such as the Uban series (trade name, manufactured by Mitsui Chemicals, Inc.). In particular, a solvent-based or solvent-free hydrophobic melamine resin curing agent is preferable from the viewpoint of encapsulation of the curing agent (III) by the polymer (II).

The content of the curing agent (III) is preferably 10 to 150 parts by mass with respect to 100 parts by mass of the polymer (II) from the viewpoint of encapsulation of the curing agent (III) by the polymer (II). If it is 150 parts by mass or less, the storage stability and the obtained coating film are excellent in appearance. If it is 10 parts by mass or more, the coating film obtained by forming the crosslink is excellent in water resistance, moisture resistance, and coating film hardness. It is more preferably 20 to 100 parts by mass, and even more preferably 40 to 100 parts by mass.

[Phase inversion emulsification process]
The present invention is an aqueous coating material obtained by a phase inversion emulsification step of a solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III). When a curing agent (III) is added after phase inversion emulsification of an organic solvent mixture containing only the organic solvent (I) and the polymer (II), the curing agent (III) is sufficiently contained in the polymer (II). It is not preferable because it cannot be done.

As a method of phase inversion emulsification in the present invention, for example, a basic compound is added to a solvent-based mixture containing an organic solvent (I) and a polymer (II) obtained by solution polymerization, and the carboxyl of the polymer (II) is carboxylated. A solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III) obtained by neutralizing all or a part of the groups with a basic compound and further adding a curing agent (III). And water are mixed, and a method of dispersing this solvent-based mixture in water can be mentioned. As a method of mixing the solvent-based mixture and water, a method of adding water to the solvent-based mixture or a method of adding the solvent-based mixture to water is preferable. Further, a solvent-based mixture obtained by adding a curing agent (III) to a solvent-based mixture containing an organic solvent (I) and a polymer (II) and water containing a basic compound are mixed to form a solvent-based mixture. Can also be dispersed in water. In the present invention, the polymer (II) in which all or a part of the carboxyl groups are neutralized with a basic compound is also referred to as "polymer (II)" for convenience.

Examples of the basic compound used for neutralizing the carboxyl group of the polymer (II) include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol and 2-. Diethylaminoethanol, 1-amino-2-propanol, 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3- Examples thereof include dimethylamino-1-propanol, 2-propylaminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholin, sodium hydroxide and potassium hydroxide. These can be used alone or in combination of two or more.

The amount of the basic compound used is such that the degree of neutralization, that is, the molar ratio of the basic compound to the carboxyl group is 40 to 150%, preferably 60 to 120%, and more preferably 80 to 110%.

Further, the temperature at the time of phase inversion emulsification is preferably 90 ° C. or lower, more preferably 80 ° C. or lower, still more preferably 70 ° C. or lower, from the viewpoint of encapsulation of the curing agent (III) by the polymer (II).

[Other compounding agents]
This water-based coating material contains various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-dripping agents, matting agents, ultraviolet absorbers, light stabilizers, etc., from the viewpoint of exhibiting excellent performance as coating materials. Various additives such as antioxidants, heat resistance improvers, slip agents, preservatives, plasticizers, and film-forming aids may be blended.

Further, as this water-based coating material, other water-dispersible resins such as polyester resin, polyurethane resin, acrylic resin, acrylic silicone resin, silicone resin, fluorine resin, epoxy resin and other water-dispersible resins and water-soluble resins are used. It may be blended.

[Painted material]
The water-based coating material of the present invention can be coated on various base materials to obtain a coated material. Examples of the base material include metal base materials such as iron and aluminum, organic base materials such as various plastics, and inorganic substrates such as glass and cement mortar.

As a method of applying the water-based coating material to the surface of various substrates, for example, various coating methods such as a spray coating method, a roller coating method, a bar coating method, an air knife coating method, a brush coating method, and a dipping method can be appropriately selected. it can.

After coating, a coating film can be obtained by drying at room temperature or heating and drying at room temperature or higher and 200 ° C. or lower. The drying temperature is preferably 100 to 200 ° C.

Examples of the present invention are shown below. In addition, "part" in this Example means "mass part".
[Manufacturing Example 1]
The following organic solvent is charged into a flask equipped with a stirrer, a reflux condenser, a temperature control device, and a dropping pump, the internal temperature of the flask is raised to 146 ° C., and then the following monomers, initiator and chain transfer agent are added. The containing mixture A was added dropwise over 3 hours. The internal temperature was maintained at 120 ° C. during the dropping.

Process (1)
Organic solvent:
PMA (Propylene Glycol Monomethyl Ether Acetate) 30.0 Parts Mixture A:
Monomer (a):
2-Hydroxyethyl methacrylate 14.0 parts Monomer (c):
Styrene 6.0 parts Methyl methacrylate 25.0 parts n-Butyl methacrylate 39.8 parts Glycidyl methacrylate 0.2 parts Initiator:
Perbutyl I (trade name, manufactured by NOF CORPORATION) 1.1 parts Chain transfer agent:
α-Methylstyrene dimer 1.0 part

Subsequently, the mixture B containing the following monomer and initiator was added dropwise over 1 hour. The internal temperature was maintained at 146 ° C. during the dropping.
Process (2)
Mixture B:
Monomer (a):
2-Hydroxyethyl methacrylate 10.0 parts Monomer (b):
Acrylic acid 1.6 parts Monomer (c):
n-Butyl Methacrylate 3.4 Part Initiator:
Perbutyl I 0.3 part

Then, the internal temperature was cooled to 120 ° C., and 2.0 parts of dimethylethanolamine was added dropwise over 0.25 hours to obtain a resin solution 1. The solid content was 75.9%.

[Manufacturing Example 2]
A resin solution 2 was obtained in the same manner as in Production Example 1 except that the organic solvent was changed as shown in Table 1. The solid content was 75.7%.

[Example 1]
A solvent-based mixture containing the following resin solution and curing agent (III) was charged into a flask equipped with a stirrer, a reflux condenser, a temperature control device, and a dropping pump, and the internal temperature of the flask was raised to 60 ° C. Ionized water was added dropwise over 30 minutes. The internal temperature was maintained at 60 ° C. during the dropping. The mixture was cooled to room temperature to obtain an aqueous coating material.

Phase inversion emulsification process Solvent-based mixture:
Resin solution 1 135 parts SBN-70D (trade name, manufactured by Asahi Kasei Corporation) 78 parts Deionized water: 178 parts

Using the obtained water-based dressing, the gloss, water resistance, moisture resistance and pencil hardness were evaluated by the following methods. The results are shown in Table 1.

[Evaluation method]
Preparation of coating plate for evaluation The water-based coating material was coated on a single-point perforated dull steel plate (electrodeposition and intermediate coating product, manufactured by Miki Coating Co., Ltd.) with bar coater # 48, and dried at 140 ° C. for 30 minutes. The obtained coated plate was used as a coated plate for evaluation of gloss, water resistance, moisture resistance, and pencil hardness.

(1) The glossiness of the coated plate for gloss evaluation was measured with a gloss meter VG7000 (trade name, manufactured by Nippon Denshoku Kogyo Co., Ltd.) at a measurement angle of 20 degrees, and evaluated according to the following criteria.
"○": Gloss at 20 degrees is 80 or more "△": Gloss at 20 degrees is 70 or more and less than 80 "×": Gloss at 20 degrees is less than 70

(2) Immerse the coating plate for water resistance evaluation in warm water at 50 ° C. for 500 hours, and measure the degree of whitening ΔL of the coating film immediately after pulling up with the Spectrocolor Meter SE-2000 (trade name, manufactured by Nippon Denshoku Kogyo Co., Ltd.). It was measured and evaluated according to the following criteria.
“○”: ΔL is 1.0 or less “Δ”: ΔL is greater than 1.0 and 2 or less “×”: ΔL is greater than 2.

(3) The coating plate for moisture resistance evaluation is stored at 50 ° C. × 95% RH for 500 hours, and the whitening degree ΔL of the coating film immediately after pulling up is measured by Spectrocolor Meter SE-2000 (trade name, manufactured by Nippon Denshoku Kogyo Co., Ltd.). And evaluated according to the following criteria.
“○”: ΔL is 1.0 or less “Δ”: ΔL is greater than 1.0 and 2 or less “×”: ΔL is greater than 2.

(4) The coated plate for evaluation of pencil hardness was scratched at an angle of 45 degrees using a Mitsubishi pencil uni in accordance with JIS K5600, and the maximum hardness that was not scratched was defined as the pencil hardness and evaluated according to the following criteria.
"○": Pencil hardness is H or more "△": Pencil hardness is HB or more and F or less "×": Pencil hardness is B or less

[Examples 2 to 4]
An aqueous coating material was obtained and evaluated in the same manner as in Example 1 except that the resin solution, the curing agent (III), and the deionized water were changed as shown in Table 2. The results are shown in Table 2.

[Comparative Example 1]
The following resin solution was charged into a flask equipped with a stirrer, a reflux condenser, a temperature control device and a dropping pump, the internal temperature of the flask was raised to 60 ° C., and then the following deionized water was dropped over 30 minutes. The internal temperature was maintained at 60 ° C. during the dropping. After cooling to room temperature, the following curing agent (III) and deionized water were added as a post-blending step to obtain an aqueous coating material, which was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Phase inversion emulsification process Resin solution 1: 135 parts Deionized water: 118 parts
Post-blending process WM44-L70G (trade name, manufactured by Asahi Kasei Corporation): 78 parts Deionized water: 10 parts

[Comparative Examples 2 to 5]
An aqueous coating material was obtained and evaluated in the same manner as in Comparative Example 1 except that the curing agent (III) and deionized water in the post-blending step were changed as shown in Table 3. The results are shown in Table 3.

The abbreviations in Tables 1, 2 and 3 indicate the following compounds. The units in Tables 1, 2 and 3 are all parts by mass except for the evaluation results.
PMA: Propropylene Glycol Monomethyl Ether Acetate DMFDG: Dipropylene Glycol Dimethyl Ether 2-HEMA: 2-Hydroxyethyl Methacrylate St: Styrene MMA: Methyl Methacrylate n-BMA: n-Butyl Methacrylate GMA: Glycidyl Methacrylate AA: SBN-70D Acrylic Acid: Block polyisocyanate curing agent, trade name, manufactured by Asahi Kasei Co., Ltd. 17B-60P: Block polyisocyanate curing agent, trade name, manufactured by Asahi Kasei Co., Ltd. Cymel 202: melamine resin curing agent, trade name, manufactured by Nippon Cytec Industries Co., Ltd. WM44-L70G: Water-dispersible block polyisocyanate hardener, trade name, manufactured by Asahi Kasei Co., Ltd. BWD-102: Water-dispersible block polyisocyanate hardener, trade name, manufactured by Nippon Polyurethane Co., Ltd.

It can be said that all of Examples 1 to 4 are excellent water-based coating materials because the obtained coated plate has good appearance, water resistance, moisture resistance, and coating film hardness.
On the other hand, the aqueous coating materials of Comparative Examples 1 to 5 are obtained by a production method that does not include a phase inversion emulsification step of a solvent-based mixture containing an organic solvent (I), a polymer (II), and a curing agent (III). Since the curing agent (III) could not be sufficiently contained in the polymer (II), the appearance, water resistance, moisture resistance, coating film hardness and the like were insufficient.

Claims (4)

An aqueous coating material obtained by a phase inversion emulsification step of a solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III), wherein 60% by mass or more of the organic solvent (I) is Fedors. solubility parameter according to the law (SP value) is an organic solvent 9.00 (cal ^/ cm ^{3) 1/2} or less, the polymer (II) is a polymer having a hydroxyl group and a carboxyl group, wherein the organic The step (1) of obtaining a dispersion liquid containing the polymer (P) obtained by polymerizing the radically polymerizable monomer (A) in the solvent (I) in the presence of the α-methylstyrene dimer, and the above-mentioned weight. The radically polymerizable monomer (B) is polymerized in the dispersion containing the coalescence (P) to obtain a dispersion containing the polymer (Q) obtained by polymerizing the radically polymerizable monomer (B). An aqueous coating material produced by a method including step (2). The aqueous coating material according to claim 1, wherein the curing agent (III) is a block polyisocyanate curing agent and / or a melamine resin curing agent. A coating product obtained by coating at least a part of the surface of a base material with the water-based coating material according to claim 1 or 2. A method for producing an aqueous coating material, which comprises a step of phase inversion emulsification of a solvent-based mixture containing an organic solvent (I), a polymer (II) and a curing agent (III), wherein 60% by mass of the organic solvent (I) is used. The above is an organic solvent having a solubility parameter (SP value) of 9.00 (cal / cm ³ ) ^1/2 or less by the Fedors method, and the polymer (II) is a polymer having a hydroxyl group and a carboxyl group. The step (1) of obtaining a dispersion liquid containing the polymer (P) obtained by polymerizing the radically polymerizable monomer (A) in the presence of the α-methylstyrene dimer in the organic solvent (I). , A dispersion containing a polymer (Q) obtained by polymerizing a radically polymerizable monomer (B) and polymerizing the radically polymerizable monomer (B) in a dispersion containing the polymer (P). A method for producing an aqueous coating material, which is produced by a method including the step (2) for obtaining a liquid.