JP7243263B2 - Aqueous resin composition and coating agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to an aqueous resin composition and a coating agent.

Coating agents are used to prevent deterioration of the surfaces of various substrates and to change the surface properties of the substrates. Aluminum fins used in air conditioners, etc., require surface hydrophilicity and corrosion resistance. In particular, the ability to maintain hydrophilicity and corrosion resistance even under conditions where wet/low temperature conditions and dry/high temperature conditions are repeated. (hydrophilic persistence) is required.

As a coating agent for achieving such surface hydrophilicity and hydrophilicity persistence, a copolymer obtained from acrylic acid, acrylate, maleic acid, maleate, itaconic acid, itaconate, etc., acrylamide, and acrylonitrile is used. Hydrophilic coating agents involving coalescence have been proposed (see, for example, US Pat. In addition, a hydrophilic treatment agent containing a hydrophilic monomer having a polymerizable double bond and a polyoxyalkylene chain, a hydrophilic polymer obtained from an acrylamide monomer or the like, and a cross-linking agent has been proposed (for example, patent Reference 2).

JP 2004-10764 A Japanese Unexamined Patent Application Publication No. 2017-20015

However, the conventionally known hydrophilizing agents described above may not be sufficiently satisfactory in maintaining hydrophilicity. The present invention has been made in view of the above circumstances, and while exhibiting initial surface hydrophilicity and corrosion resistance, hydrophilicity and corrosion resistance are maintained even under conditions where wet/low temperature conditions and dry/high temperature conditions are repeated. An object of the present invention is to provide a water-based resin composition that can maintain hydrophilicity and can exhibit persistence of hydrophilicity.

The aqueous resin composition of the present invention comprises an acrylic polymer (A), a urethane resin (B), and an aqueous medium (C), wherein the acrylic polymer (A) is a (meth)acrylamide monomer and , an unsaturated carboxylic acid or its anhydride, and a monomer component containing at least a monomer having a polyoxyalkylene unit and a polymerizable unsaturated group, and having a weight average molecular weight of 230,000 That's it.

By using the water-based resin composition of the present invention, the hydrophilicity and corrosion resistance can be maintained even under conditions where wet/low temperature conditions and dry/high temperature conditions are repeated while exhibiting initial surface hydrophilicity and corrosion resistance. It is possible to provide an aqueous resin composition capable of exhibiting hydrophilicity persistence.

The aqueous resin composition of the present invention contains an acrylic polymer (A), a urethane resin (B), and an aqueous medium (C).

The acrylic polymer (A) comprises a (meth)acrylamide monomer (a1), an unsaturated carboxylic acid or its anhydride (a2), and a monomer having a polyoxyalkylene unit and a polymerizable unsaturated group ( a3), and is a copolymer of the monomer components.

As the (meth)acrylamide monomer (a1), one or more can be used, and (meth)acrylamide; (meth)acrylonitrile; (meth)acrylamide, N-methylol(meth)acrylamide, N -N-monosubstituted (meth)acrylamide monomers such as methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide; ) acryloylmorpholine, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloyl-4-piperidone, N,N-dimethyl(meth)acrylamide, N , N-diethyl(meth)acrylamide, N,N-methylenebis(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide and other N,N-disubstituted (meth)acrylamide monomers.

The content of the (meth)acrylamide monomer (a1) in the monomer component is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably It is 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

As the unsaturated carboxylic acid or its anhydride (a2), one or two or more can be used, and unsaturated monocarboxylic acids such as (meth)acrylic acid; β-carboxyethyl (meth)acrylate; (Meth) acrylic esters of monocarboxylic acids such as 2-(meth) acryloylpropionic acid; unsaturated dicarboxylic acids such as crotonic acid, itaconic acid, maleic acid, fumaric acid, phthalic acid, and succinic acid; half (meth)acrylic acid ester; anhydride of the unsaturated dicarboxylic acid; (meth)acryloxyalkyl group (preferably (meth)acryloxyethyl group) added to at least one of the carboxy groups of the unsaturated dicarboxylic acid and the like. Among them, unsaturated monocarboxylic acids are preferred, and acrylic acid is particularly preferred.

The content of the unsaturated carboxylic acid or its anhydride (a2) is preferably 0.5% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, in the monomer component, More preferably, it is 5% by mass or less.

The monomer (a3) having a polyoxyalkylene unit and a polymerizable unsaturated group is a monomer in which the polyoxyalkylene unit and the polymerizable unsaturated group are bonded directly or via a linking group. , the linking group includes -CO-, -O-, -NH-, a divalent hydrocarbon group (an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, a hydrogen group, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a group having 20 or less carbon atoms in combination thereof), or a group in which these are combined, and -CO- is preferred. At the other end of the polyoxyalkylene unit (the end to which the polymerizable unsaturated group is not bonded), -OR (R is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a group having 20 or less carbon atoms in combination thereof) may be bonded, and the R is an aliphatic hydrocarbon A group (preferably an alkyl group) is preferred, and the number of carbon atoms in the aliphatic hydrocarbon group is preferably 1-5, more preferably 1-2.

The polyoxyalkylene unit preferably contains an oxyethylene unit. The content of oxyethylene units in the polyoxyalkylene units is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and the upper limit is 100% by mass.

In the polyoxyalkylene unit, the repeating number of the oxyalkylene unit is preferably 3 or more, more preferably 5 or more, still more preferably 7 or more, preferably 20 or less, more preferably 18 or less, and still more preferably 15 or less. is.

The number average molecular weight of the monomer (a3) having a polyoxyalkylene unit and a polymerizable unsaturated group is preferably 200 or more, more preferably 300 or more, still more preferably 400 or more, and preferably 1,500 or less. , more preferably 1,000 or less, still more preferably 800 or less, and even more preferably 600 or less.

The monomer component is other than the (meth)acrylamide monomer (a1), the unsaturated carboxylic acid or its anhydride (a2), and the monomer (a3) having an oxyalkylene unit and a polymerizable unsaturated group. may contain other monomers (a4).

Examples of the other monomer (a4) include (meth)acrylic acid esters, acrylic monomers having a hydrophilic group (hydroxy group, imide group, cyano group, amino group, sulfonic acid group, quaternary ammonium group, etc.), monomers, other vinyl compounds, and the like.

As the (meth)acrylic acid ester, one or two or more can be used, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and (meth)acrylate. Isopropyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, (meth)acrylic acid neopentyl, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate , n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate and other aliphatic (meth)acrylic acid esters; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopenta (meth)acrylate Alicyclic (meth) acrylic esters such as nil, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate; benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) ) aromatic (meth)acrylic acid esters such as phenyl acrylate.

As the acrylic monomer having an imide group, one or two or more can be used, for example, (meth)acrylimide, N-methylolmaleimide, N-hydroxyethylmaleimide, N-glycidylmaleimide, N- 4-chloromethylphenylmaleimide, N-acetoxyethylmaleimide and the like.

As the acrylic monomer having a cyano group, one or two or more can be used. Cyanopropyl acrylate, 1-cyanocyclopropyl acrylate, 1-cyanocycloheptyl acrylate, 1,1-dicyanoethyl acrylate, 2-cyanophenyl acrylate, 3-cyanophenyl acrylate, 4-cyanophenyl acrylate, 3-cyanobenzyl acrylate, 4-cyanobenzyl acrylate and the like.

As the acrylic monomer having an amino group, one or more may be used. Examples include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-tert-butylaminoethyl (meth) ) acrylate, (meth)acryloxyethyltrimethylammonium chloride and the like.

As the acrylic monomer having a quaternary ammonium group, one or more may be used, and examples thereof include tetrabutylammonium (meth)acrylate and trimethylbenzylammonium (meth)acrylate.

As the acrylic monomer having a sulfonic acid group, one or two or more can be used. Examples include sodium sulfopropyl(meth)acrylate, sodium 2-sulfoethyl(meth)acrylate, 2-acrylamide-2- and sodium methylpropanesulfonate.

One or more of these other vinyl compounds may be used, and examples thereof include styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

The content of the other monomer (a4) is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 3% by mass or less in the monomer component, and the lower limit is 0% by mass. %.

The acrylic polymer (A) can be obtained by polymerizing the monomer component. Examples of the polymerization method include a radical polymerization method, an anion polymerization method, a cationic polymerization method and the like, and a radical polymerization method is preferred. At the time of polymerization, one or more polymerization initiators can be used. Specific examples of the polymerization initiator include 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2′-azobis[2-(2-imidazoline- 2-yl)propane]disulfate, 2,2′-azobis[2-(2-imidazolin-2-yl)propane], 2,2′-azobisisobutyronitrile, 2,2′-azobis( 2-amidinopropane) dihydrochloride, 2,2′-azobis(2-methylpropionamidine) dihydrochloride, 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate , 2,2′-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride, 2,2′-azobis(1-imino-1-pyrrolidino-2 -methylpropane) dihydrochloride, 2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2′-azobis[2- methyl-N-(2-hydroxyethyl)propionamide], 2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2′-azobis(N , N′-dimethylene isobutylamidine); hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cumene hydroperoxide Examples include peroxide initiators such as oxides; persulfate initiators; carbonyl initiators; redox initiators, etc., and azo initiators are preferred.

The polymerization can be carried out in water, a hydrophilic organic solvent, or a mixture of water and a hydrophilic organic solvent. Examples of the hydrophilic solvent include alcohol solvents such as methanol, ethanol, n-propanol, and isopropyl alcohol; acetone; , ketone solvents such as methyl ethyl ketone; alkylene glycol solvents such as ethylene glycol, diethylene glycol and propylene glycol; alkyl ether solvents of polyalkylene glycol; and lactam solvents such as N-methyl-2-pyrrolidone.

The weight average molecular weight of the acrylic polymer (A) is 230,000 or more, preferably 250,000 or more, more preferably 260,000 or more, for example 1,000,000 or less, 700,000 or less, It may be 500,000 or less.

The weight average molecular weight of the acrylic polymer (A) can be measured by gel permeation chromatography as a converted value using polystyrene as a standard sample.

The urethane resin (B) is a polymer having a urethane bond in the molecule, and includes a polyol (b1), a polyisocyanate (b2), and optionally a chain extender (b3) and/or a terminal terminator ( It is preferably a reaction product with b4). When using the chain extender (b3) and/or the terminal terminator (b4), the polyol (b1) and the polyisocyanate (b2) are reacted to form a urethane prepolymer having an isocyanate group at the end, the chain extender (b3 ) and/or a terminal terminator (b4).

Examples of the polyol (b1) include polymer polyol (b1-1) of polyether polyol, polyester polyol, polycarbonate polyol, and polyolefin polyol; polyol (b1-2) having a hydrophilic group; low molecular weight polyol (b1-3), etc. is mentioned.

The number average molecular weight of the polymer polyol (b1-1) is preferably 500 or more, more preferably 800 or more, preferably 5,000 or less, more preferably 4,000 or less, and still more preferably 3,000 or less. be.

As the polyether polyol, for example, one or more compounds having two or more active hydrogen atoms such as ethylene glycol and diethylene glycol are used as an initiator as necessary, and addition polymerization of alkylene oxide is performed. is mentioned.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, trimethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4- butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, sorbitol, sucrose, aconite sugar, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanolamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol and the like.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran and the like.

As the polyether polyol, polyoxytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran is preferable.

The number average molecular weight of the polyether polyol is preferably 500 or more and 3,000 or less.

The polyester polyol includes, for example, a polyester polyol obtained by reacting a low molecular weight polyol with a polycarboxylic acid; a polyester polyol obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone; Examples include polyester polyols obtained by polymerization.

As the low-molecular-weight polyol used in the production of the polyester polyol, one or two or more can be used. Examples include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, , 3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neo Pentyl glycol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane diol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl- 1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin, trimethylolpropane, ditrimethylolpropane, trimethylolpropane, pentaerythritol, etc. with a molecular weight of 50 Aliphatic polyols having a molecular weight of 300 or more; polyols having an alicyclic structure such as cyclohexanedimethanol and hydrogenated bisphenol A; polyols having an aromatic structure such as bisphenol A and bisphenol F;

As the polycarboxylic acid, one or two or more can be used. For example, aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid; 1,4-cyclohexanedicarboxylic acid, cyclohexane alicyclic polycarboxylic acids such as tricarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid; and anhydrides and esters thereof.

Examples of the polycarbonate polyol include an esterification reaction product of a carbonate ester and a polyhydric alcohol, a reaction product of a polyhydric alcohol and phosgene, and the like.

As the carbonate ester, one or more kinds can be used. Aromatic carbonates may be mentioned (hereinafter, those containing an aromatic structure may be collectively referred to as "aromatic"). The aliphatic carbonates include saturated aliphatic carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, ethyl-n-butyl carbonate, ethyl isobutyl carbonate; ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,3-pentylene carbonate, 1, and unsaturated aliphatic carbonates such as 4-pentylene carbonate, 1,5-pentylene carbonate, 2,3-pentylene carbonate and 2,4-pentylene carbonate. Aromatic carbonates include diphenyl carbonate, dibenzyl carbonate and the like.

As the polyhydric alcohol, one or more can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, diethylene glycol, Linear or branched diols such as propylene glycol, triethylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; trimethylolmethane , trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol.

Examples of the polyolefin polyol include polyethylene polyol, polypropylene polyol, polyisobutene polyol, hydrogenated (hydrogenated) polybutadiene polyol, and hydrogenated (hydrogenated) polyisoprene polyol.

As the polymer polyol (b1-1), polyether polyol, polyester polyol and polycarbonate polyol are preferable.

The content of the polymer polyol (b1-1) in the polyol (b1) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 93% by mass or more, and the upper limit is 100% by mass. is.

Examples of the polyol (b1-2) having a hydrophilic group include polyols having an anionic group, polyols having a cationic group, polyols having a nonionic group, and polyols having an anionic group or a cationic group. is preferred, and a polyol having an anionic group is more preferred.

Examples of the polyol having an anionic group include polyol having a carboxyl group and polyol having a sulfonic acid group.

Examples of polyols having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. Among these, 2,2-dimethylolpropionic acid is preferred. In addition, a polyester polyol having a carboxyl group obtained by reacting the polyol having the carboxyl group with various polycarboxylic acids can also be used.

Examples of the polyol having a sulfonic acid group include dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5[4-sulfophenoxy]isophthalic acid, salts thereof, and the aromatic structure. Polyester polyol obtained by reacting with a low-molecular-weight polyol exemplified as usable for the production of polyester polyol having

It is preferable that part or all of the anionic groups are neutralized with a basic group or the like. Examples of the basic compound include organic amines having a boiling point of 200° C. or higher, such as ammonia, triethylamine, morpholine, monoethanolamine, and diethylethanolamine, and metallic water containing sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like. oxides and the like. From the viewpoint of improving the water dispersion stability of the urethane resin composition, the basic compound has a basic group/anionic group in the range of 0.5 to 3.0 (molar ratio). It is preferable to use it, and it is more preferable to use it in the range of 0.8 to 2.0 (molar ratio).

Examples of polyols having a cationic group include polyols having a tertiary amino group. Specific examples include N-methyl-diethanolamine, polyol obtained by reacting a compound having two epoxies in one molecule with a secondary amine, and the like.

The cationic groups are preferably partially or wholly neutralized with an acidic compound such as formic acid, acetic acid, propionic acid, succinic acid, glutaric acid, tartaric acid and adipic acid.

Moreover, it is preferable that part or all of the tertiary amino group as the cationic group is quaternized. Examples of the quaternizing agent include dimethyl sulfate, diethyl sulfate, methyl chloride, and ethyl chloride. Among these, it is preferable to use dimethyl sulfate.

Examples of polyols having nonionic groups include polyols having a polyoxyethylene structure.

The content of the polyol (b1-2) having a hydrophilic group is preferably 0.3% by mass or more and 10% by mass or less in the polyol (b1).

The low molecular weight polyol (b1-3) is a polyol having a molecular weight of less than 500 (preferably 450 or less, more preferably 400 or less, the lower limit is about 50), such as ethylene glycol, diethylene glycol, 1,2- Propylene glycol, dipropylene glycol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol , 1,4-cyclohexanediol, 1,6-hexanediol, and cyclohexanedimethanol; cyclobutanediol, cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, Alicyclic polyols such as cyclohexanedimethanol, hydroxypropylcyclohexanol, dicyclohexanediol, hydrogenated bisphenol A, 1,3-adamantanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol; bisphenol A, Examples include bisphenol F, bisphenol AD, and aromatic polyols such as ethylene oxide and propylene oxide adducts thereof.

When the low-molecular-weight polyol (b1-3) is included, its content is preferably 0.1% by mass or more and 15% by mass or less in the polyol (b1).

As the polyisocyanate (b2), one or more can be used, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, lysine diisocyanate methyl ester, xylylene diisocyanate, tetramethylxylylene diisocyanate, and the like. These aliphatic polyisocyanates can be used alone or in combination of two or more.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2′-dimethyldicyclohexylmethane diisocyanate, bis( 4-isocyanato-n-butylidene)pentaerythritol, dimic acid diisocyanate, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2- isocyanatomethyl-3-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-isocyanate Natomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanate Natomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)- 6-(2-isocyanatoethyl)-bicyclo[2,1,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2 ,2,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2,2,1]-heptane, norbornene diisocyanate and the like. It is preferably a saturated alicyclic polyisocyanate, preferably a monocyclic (having no condensed ring) alicyclic polyisocyanate. These alicyclic polyisocyanates can be used alone or in combination of two or more.

Examples of the aromatic polyisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and the like. These aromatic polyisocyanates can be used alone or in combination of two or more.

Among them, from the viewpoint of the hydrophilicity of the coating film to be obtained, it is preferable to contain an alicyclic polyisocyanate and an aromatic polyisocyanate, and it is more preferable to contain an alicyclic polyisocyanate.

The molar ratio (NCO/OH) between the isocyanate groups contained in the polyisocyanate (b2) and the hydroxyl groups contained in the polyol (b1) is preferably 1.05 or more, preferably 3 or less, and more preferably 2 or less.

The chain extender (b3) is a compound having two or more groups having active hydrogen atoms in the molecule (preferably substituted or unsubstituted amino groups), and one or two or more of them can be used. , for example, ethylenediamine, 1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,4-cyclohexanediamine, 3-aminomethyl-3,5, 5-trimethylcyclohexylamine (isophoronediamine), 4,4′-dicyclohexylmethanediamine, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2 .2.1] diamine compounds such as heptane, 1,3-bis(aminomethyl)cyclohexane, hydrazine, o-tolylenediamine, m-tolylenediamine and p-tolylenediamine; triamine compounds such as diethylenetriamine; Polyamine compounds having 4 or more amino groups, such as tetramine and tetraethylenepentamine, are included.

The chain extender is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass, relative to 100 parts by mass of the urethane prepolymer. parts or less, more preferably 5 parts by mass or less.

As the terminal terminator (b4), a compound having one group having an active hydrogen atom in the molecule (preferably a substituted or unsubstituted amino group or hydroxyl group) or a compound having a hydroxyl group and an active hydrogen atom in the molecule group (preferably substituted or unsubstituted amino group or hydroxyl group).

Examples of compounds having one group having an active hydrogen atom (preferably a substituted or unsubstituted amino group or hydroxyl group) in the molecule include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and nonanol. , monoalcohol compounds such as undecanol; and monoamine compounds such as ammonia, dibutylamine and aminosilane.

Examples of the compound having a hydroxyl group and a group having an active hydrogen atom (preferably a substituted or unsubstituted amino group or hydroxyl group) in the molecule include diol compounds such as propanediol, butanediol, pentanediol, and hexanediol; Examples include aminoalcohol compounds such as ethanolamine and diethanolamine.

The terminal terminator (b4) is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 20 parts by mass or less, more preferably 100 parts by mass of the urethane prepolymer. is 10 parts by mass or less.

The urethane resin (B) is produced by reacting the polyol (b1), the polyisocyanate (b2), and optionally a chain extender (b3) and/or a terminal terminator (b4). can do. The reaction temperature is preferably 50-150°C. In addition, a urethanization catalyst such as an organic tin compound may coexist during the reaction.

When a polyol having an anionic group is used as the polyol having a hydrophilic group, the acid value of the urethane resin is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and preferably 70 mgKOH/g or less. More preferably, it is 50 mgKOH/g or less.

The mass ratio ((A)/(B)) of the acrylic polymer (A) and the urethane resin (B) is preferably 5/95 or more, more preferably 10/90 or more, and preferably 50/50. Below, more preferably below 40/60.

The urethane resin (B) may be dispersed in advance in part or all of the aqueous medium (C) and then mixed with the acrylic polymer (A) and the aqueous medium (C) described below.

Examples of the aqueous medium (C) include water, water-miscible organic solvents, and mixtures thereof. Examples of water-miscible organic solvents include alcohol solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, 1,2-propylene glycol and 1,3-butylene glycol; ketone solvents such as acetone and methyl ethyl ketone; and ethylene. Glycol-n-butyl ether, diethylene glycol-n-butyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol methyl ether lactam solvents such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone; and amide solvents such as N,N-dimethylformamide. These water-miscible organic solvents can be used alone or in combination of two or more.

The aqueous medium (C) is preferably water alone or a mixture of water and an organic solvent miscible with water, more preferably water alone, in consideration of safety and reduction of environmental load.

The content of the aqueous medium (C) is preferably 30 to 80% by mass, more preferably 50 to 70% by mass, based on the total amount of the aqueous resin composition.

The aqueous resin composition contains, in addition to the acrylic polymer (A) and the aqueous medium (C), if necessary, a crosslinking agent, a plasticizer, an antistatic agent, a wax, a surfactant, a light stabilizer, a fluid Other additives such as modifiers, dyes, leveling agents, rheology control agents, UV absorbers, antioxidants, photocatalytic compounds, inorganic pigments, organic pigments, and extender pigments may also be included.

Examples of the cross-linking agent include amino resins, aziridine compounds, melamine compounds, epoxy compounds, oxazoline compounds, carbodiimide compounds, isocyanate compounds, and the like.

Moreover, by using the surfactant, the blending stability of the urethane resin composition of the present invention can be further improved. When using a surfactant, it is preferable to use it in the range of 20 parts by mass or less with respect to 100 parts by mass of the urethane resin (A), since the adhesion to the substrate of the resulting coating film can be maintained. preferably not used.

The content of the other additives is, for example, 30% by mass or less, for example 20% by mass or less, and the lower limit is 0% by mass, and is 0.1% by mass or more in the non-volatile content of the aqueous resin composition. may

A coating agent comprising the aqueous resin composition is also included in the technical scope of the present invention. Examples of base materials for the coating agent include metals, various plastics and their films, glass, paper, and wood.

Examples of the metal substrate include galvanized steel sheets, aluminum-galvanized steel sheets, aluminum sheets, aluminum alloy sheets, electromagnetic steel sheets, copper sheets, stainless steel sheets, and the like, which are used in applications such as automobiles, home appliances, and building materials.

As the plastic base material, acrylonitrile-butadiene-styrene resin (ABS resin), polycarbonate resin (PC resins), ABS/PC resins, polystyrene resins (PS resins), polymethyl methacrylate resins (PMMA resins), acrylic resins, polypropylene resins, polyethylene resins, etc., and plastic film substrates include polyethylene terephthalate film and polyester film. , polyethylene film, polypropylene film, TAC (triacetylcellulose) film, polycarbonate film, polyvinyl chloride film and the like can be used.

Examples of the coating agent include aluminum fins; building members such as exterior walls and roofs; civil engineering members such as guardrails, soundproof walls and drains; household appliances; industrial machinery; anti-fogging materials such as; mirrors; and surface coating of various articles such as medical instruments. Articles having coating films of these coating agents are also included in the technical scope of the present invention.

A coating film can be formed by applying the aqueous resin composition to a substrate, drying and curing the composition. Examples of the coating method include a spray method, a curtain coater method, a flow coater method, a roll coater method, a brush coating method, and an immersion method. The drying may be natural drying at room temperature, but may also be drying by heating. The drying by heating is preferably carried out at 40 to 250° C. for about 1 to 600 seconds.

The water-based resin composition can exhibit initial hydrophilicity, corrosion resistance, and hydrophilicity persistence even when the thickness of the crosslinked coating film is, for example, 10 μm or less (further, 5 μm or less, 2.5 μm or less). The lower limit of the thickness of the crosslinked coating film is, for example, 0.1 μm.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, the weight average molecular weight of the acrylic polymer was measured by the following method.

[Method for measuring weight average molecular weight of acrylic polymer]
The weight average molecular weight of the acrylic polymer (A) was measured under the following conditions.
HPLC: Shimadzu/L20 system
Column: Shodex OHpak SB-806MHQ
(8.0 mm I.D. x 300 mm L. x 2)
Guard column: Shodex OHpak SB-G
(4.6 mm I.D. x 10 mm L.)
Column temperature: 40°C
Eluent: 0.2 mol/L sodium nitrate aqueous solution Flow rate: 0.70 mL/min
Detector: RI, UV254nm
Injection volume: 50 μL
Method used: 0.2M_NaNO3. l cm

(standard sample)
"Shodex Pullulan P-800" manufactured by Showa Denko K.K.
"Shodex Pullulan P-400" manufactured by Showa Denko K.K.
"Shodex Pullulan P-200" manufactured by Showa Denko K.K.
"Shodex Pullulan P-100" manufactured by Showa Denko K.K.
"Shodex Pullulan P-50" manufactured by Showa Denko K.K.
"Shodex Pullulan P-20" manufactured by Showa Denko K.K.
"Shodex Pullulan P-10" manufactured by Showa Denko K.K.
"Shodex Pullulan P-5" manufactured by Showa Denko K.K.

(Synthesis example (A-1))
A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping device was charged with ion-exchanged water and isopropyl alcohol as polymerization solvents in a total amount of 150 parts by mass under a nitrogen atmosphere. 50 parts by mass of acrylamide (hereinafter referred to as "DMAA"), 48 parts by mass of methoxypolyethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. "AM-90G", the average number of moles of oxyethylene groups added is 9 mol), acrylic acid ( 2 parts by mass (hereinafter referred to as "AA") was charged. Next, 0.1 part by mass of an azo polymerization initiator (“VA-044” manufactured by Wako Pure Chemical Industries, Ltd.) is added dropwise, and radical polymerization is performed while the temperature is kept at 50° C. to form the acrylic polymer (A-1). A composition was obtained. The obtained acrylic polymer (A-1) composition had a weight average molecular weight of 310,000 and a non-volatile content of 40% by mass.

(Synthesis Examples (A-2) to (A-5))
Compositions of acrylic polymers (A-2) to (A-5) were obtained in the same manner as in Preparation Example 1, except that the monomer components were changed as shown in Table 1.

(Synthesis example (B-1))
In a nitrogen-purged container equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, a mixture of ethylene glycol, neopentyl glycol, terephthalic acid, isophthalic acid and adipic acid having a number average molecular weight of 1,200 was reacted. 69.8 parts by mass of polyester polyol, 2.7 parts by mass of 2,2-dimethylolpropionic acid (DMPA), 25 parts by mass of dicyclohexylmethane diisocyanate (H12MDI) and 65 parts by mass of methyl ethyl ketone are charged and reacted at 70 ° C. to form a molecule. An organic solvent solution of a urethane prepolymer having an isocyanate group at its end was obtained.

Next, the mixture is cooled to 40° C., 2 parts by mass of triethylamine is added to neutralize part or all of the carboxyl groups of the urethane prepolymer, 335 parts by mass of water is added and sufficiently stirred, and then ethylenediamine (EDA) is added. 0.5 part by mass was added to obtain an aqueous dispersion of urethane resin, followed by aging and solvent removal to obtain a composition of urethane resin (B-1) having a non-volatile content of 30% by mass.

(Synthesis example (B-2))
In a nitrogen-purged container equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, a mixture of ethylene glycol, neopentyl glycol, terephthalic acid, isophthalic acid and adipic acid having a number average molecular weight of 1,200 was reacted. By charging 76.0 parts by mass of polyester polyol, 2.9 parts by mass of 2,2-dimethylolpropionic acid (DMPA), 18.9 parts by mass of isophorone diisocyanate (IPDI) and 65 parts by mass of methyl ethyl ketone and reacting at 70 ° C., An organic solvent solution of a urethane prepolymer having an isocyanate group at the molecular end was obtained.

Next, 0.2 part by mass of 1,3-butanediol was added to the organic solvent solution of the urethane prepolymer and reacted at 70° C. to completely stop the reaction of the isocyanate component. Then, the mixture is cooled to 40° C., 2 parts by mass of triethylamine (TEA) is added to neutralize part or all of the carboxyl groups of the urethane prepolymer, and 335 parts by mass of water is added and sufficiently stirred to form a urethane resin. A composition of urethane resin (B-2) having a non-volatile content of 30% by mass was obtained by aging and removing the solvent.

(Synthesis example (B-3))
In a nitrogen-purged container equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, a mixture of ethylene glycol, neopentyl glycol, terephthalic acid, isophthalic acid and adipic acid having a number average molecular weight of 1,200 was reacted. By charging 79.2 parts by mass of polyester polyol, 3.0 parts by mass of 2,2-dimethylolpropionic acid (DMPA), 15.4 parts by mass of tolylene diisocyanate (TDI) and 65 parts by mass of methyl ethyl ketone and reacting at 70 ° C. , an organic solvent solution of a urethane prepolymer having an isocyanate group at the molecular end was obtained.

Next, 0.2 part by mass of 1,3-butanediol was added to the organic solvent solution of the urethane prepolymer and reacted at 70° C. to completely stop the reaction of the isocyanate component. Next, the mixture is cooled to 40°C, 2.3 parts by mass of triethylamine (TEA) is added to neutralize part or all of the carboxyl groups of the urethane prepolymer, and 335 parts by mass of water is added and sufficiently stirred. An aqueous dispersion of urethane resin was obtained and subjected to aging and solvent removal to obtain a composition of urethane resin (B-3) having a non-volatile content of 30% by mass.

(Preparation of Examples 1-4 and Comparative Examples 1-4)
A solution of the acrylic polymer (A) and the urethane resin (B) shown in the table below was added to a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping device, together with the acrylic polymer (A). The non-volatile content mass ratio ((A)/(B)) of the urethane resin (B) is 20/80, and the aqueous medium is An aqueous dispersion was obtained by adding 30 parts by mass of ion-exchanged water as (C). By distilling this aqueous dispersion under reduced pressure, aqueous resin compositions (1) to (4) and (D1) to (D4) having a nonvolatile content of 25% by mass were obtained.

[Preparation of test piece]
The aqueous resin compositions (1) to (4) and (D1) to (D4) obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were applied to an aluminum plate in a thickness of 1 μm, and heated at 180°C. and dried for 1 minute to prepare a test piece.

[Evaluation of corrosion resistance]
The coating film constituting the test piece was subjected to a salt spray test using a salt spray tester manufactured by Shikenki Co., Ltd. After 240 hours, the area of rust generation was visually determined and evaluated. It was measured by a method based on the JIS test method (JIS Z2371:2000).

Good: The area where rust occurred was less than 20% of the entire surface of the coating film.
Δ: The area where rust occurred was 20% or more and less than 70% of the entire coating film surface.
x: The area where rust occurred was 70% or more of the entire surface of the coating film.

[Evaluation of initial hydrophilicity]
8 μL of pure water was dropped on the surface of the test piece, and the contact angle was measured after 8 seconds.

[Evaluation of hydrophilicity retention]
After repeating the wetting-drying cycle of the test piece 20 times, 8 μL of pure water was dropped on the surface of the test piece, and the contact angle was measured after 8 seconds. The wet condition was immersion in water at 25°C for 2 minutes, and the dry condition was held at 40°C for 6 minutes.

[Evaluation of adhesion]
A 24 mm wide adhesive tape manufactured by Nichiban Co., Ltd. was attached to the surface of the primer layer of the test plate prepared by the above method. Next, the adhesive tape was pulled in a direction perpendicular to the coating film, and the state of the surface of the coating film when the adhesive tape was peeled off from the surface of the coating film was visually evaluated according to the following evaluation criteria.
⊚: The coating film did not peel off at all from the surface of the base material constituting the test plate.
◯: A small portion of the coating film was peeled off from the surface of the base material constituting the test plate, but the peeled range was less than 10% of the total area of the film constituting the test plate.
Δ: The primer layer in a range of 10% or more and less than 50% of the area of the coating film constituting the test plate was peeled off from the substrate surface constituting the test plate.
x: 50% or more of the primer layer with respect to the total area of the coating film constituting the test plate was peeled off from the substrate surface constituting the test plate.

Table 1 shows the evaluation results.

In the table, AM represents acrylamide and AA represents acrylic acid.

Examples 1 to 4 are examples of the present invention, and while exhibiting initial surface hydrophilicity and corrosion resistance, hydrophilicity and corrosion resistance are maintained even under conditions where wet/low temperature conditions and dry/high temperature conditions are repeated. and the hydrophilic retention was good. On the other hand, Comparative Examples 1 and 2 are examples in which the weight average molecular weight of the acrylic polymer is less than 230,000, and Comparative Example 3, in which the hydrophilic retention is not sufficiently satisfactory, is an example in which no urethane resin is included. , was inferior in corrosion resistance, adhesion and hydrophilic retention. Comparative Example 4 is an example containing no acrylic polymer, and was inferior in initial hydrophilicity.

Claims (6)

An aqueous resin composition comprising an acrylic polymer (A), a urethane resin (B), and an aqueous medium (C),
The acrylic polymer (A) comprises a (meth)acrylamide monomer (a1) , an unsaturated carboxylic acid or its anhydride (a2) , and a monomer having a polyoxyalkylene unit and a polymerizable unsaturated group ( a3) is formed from a monomer component containing at least
The content of the (meth)acrylamide monomer (a1) is 30% by mass or more and 70% by mass or less in the monomer component,
The content of the unsaturated carboxylic acid or its anhydride (a2) is 0.5% by mass or more and 20% by mass or less in the monomer component,
The acrylic polymer (A) has a weight average molecular weight of 230,000 or more,
The aqueous resin composition, wherein the urethane resin (B) is a reaction product of a polyol (b1) and a polyisocyanate (b2), and the polyisocyanate (b2) contains an alicyclic polyisocyanate. 2. The aqueous resin composition according to claim 1, wherein said (meth)acrylamide monomer is an N,N-disubstituted (meth)acrylamide monomer. 3. The aqueous resin composition according to claim 1, wherein said unsaturated carboxylic acid or its anhydride is methacrylic acid. 4. The aqueous resin composition according to any one of claims 1 to 3, wherein the number average molecular weight of the monomer having polyoxyalkylene units and polymerizable unsaturated groups is 200 or more and 1,500 or less. A coating agent comprising the aqueous resin composition according to any one of claims 1 to 4 . An article having a coating film of the coating agent according to claim 5 .