WO2021205834A1 - Aqueous resin composition and coating agent - Google Patents

Abstract

Provided is an aqueous resin composition comprising an acrylic polymer (A), a urethane resin (B), and an aqueous medium (C), in which the acrylic polymer (A) is formed from 2-hydroxyethylacrylamide, an unsaturated carboxylic acid or an anhydride thereof, and a monomer component comprising at least a polyoxyalkylene unit and a monomer having a polymerizable unsaturated group and has a weight average molecular weight of 100,000 or higher. A coating film obtained from the aqueous resin composition can be used suitably in various coating agents because it can exhibit persistent hydrophilicity even under conditions that impose a harsh thermal history and conditions of use after application of a processing oil and washing.

Description

Aqueous resin composition and coating agent

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

The coating agent is used to prevent deterioration of the surface of various base materials and to change the surface characteristics of the base material. Aluminum fins used in air conditioners, etc. are required to have hydrophilicity and corrosion resistance on the surface, and in particular, hydrophilicity and corrosion resistance can be maintained 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, acrylic acid, acrylate, maleic acid, maleate, itaconic acid, itaconic acid and the like, and the common weight obtained from acrylamide and acrylonitrile. Hydrophilic coating agents containing coalescing have been proposed (see, for example, Patent Document 1). Further, a hydrophilization 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, a patent). See Reference 2).

Japanese Unexamined Patent Publication No. 2004-1076 Japanese Unexamined Patent Publication No. 2017-20015

However, with the above-mentioned hydrophilization treatment agents known conventionally, there are cases where the hydrophilicity persistence is not sufficiently satisfactory. The present invention has been made in view of the above circumstances, and exhibits hydrophilicity sustainability even under conditions that give a harsh heat history for drying the coating film or under conditions where processing oil is applied and washed before use. It is an object of the present invention to provide an aqueous resin composition which can be used.

The aqueous resin composition of the present invention contains an acrylic polymer (A), a urethane resin (B), and an aqueous medium (C), and the acrylic polymer (A) is 2-hydroxyethyl (meth) acrylamide. It is formed from a monomer component containing at least an unsaturated carboxylic acid or an anhydride thereof, a polyoxyalkylene unit and a monomer having a polymerizable unsaturated group, and has a weight average molecular weight of 100. It is over 000.

By using the aqueous resin composition of the present invention, hydrophilicity can be maintained even under conditions that give a severe heat history for drying the coating film or under conditions where processing oil is applied and washed before use. A possible aqueous resin composition can be provided.

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) is a monomer (a2) having 2-hydroxyethyl (meth) acrylamide, an unsaturated carboxylic acid or an anhydride thereof (a1), a polyoxyalkylene unit and a polymerizable unsaturated group. It is formed from a monomer component containing at least and, and is a copolymer of the monomer component.

2-Hydroxyethyl (meth) acrylamide represents 2-hydroxyethyl acrylamide and / or 2-hydroxyethyl methacrylamide, and is preferably 2-hydroxyethyl acrylamide.

The content of 2-hydroxyethyl (meth) acrylamide 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 80% by mass. % Or less, more preferably 70% by mass or less, still more preferably 60% by mass or less.

As the unsaturated carboxylic acid or its anhydride (a1), one kind or two or more kinds can be used, and an unsaturated monocarboxylic acid such as (meth) acrylate; β-carboxyethyl (meth) acrylate, (Meta) acrylic ester of monocarboxylic acid such as 2- (meth) acryloylpropionic acid; unsaturated dicarboxylic acid such as crotonic acid, itaconic acid, maleic acid, fumaric acid, phthalic acid, succinic acid; Half (meth) acrylic acid ester; Anhydrous of the unsaturated dicarboxylic acid; A (meth) acryloxyalkyl group (preferably a (meth) acryloxyethyl group) is added to at least one of the carboxy groups of the unsaturated dicarboxylic acid. Examples of the compound. Among them, unsaturated monocarboxylic acid is preferable, and acrylic acid is particularly preferable.

The content of the unsaturated carboxylic acid or its anhydride (a1) is preferably 0.5% by mass or more, preferably 20% by mass or less, and more preferably 10% by mass or less in the monomer component. More preferably, it is 5% by mass or less.

The monomer (a2) having a polyoxyalkylene unit and a polymerizable unsaturated group is a monomer in which a polyoxyalkylene unit and a polymerizable unsaturated group are bonded directly or via a linking group. As the linking group, -CO-, -O-, -NH-, and a divalent hydrocarbon group (an aliphatic hydrocarbon group having 1 to 10 carbon atoms and an alicyclic hydrocarbon having 3 to 10 carbon atoms). Examples thereof include a hydrogen group, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a group in which these are combined and having a carbon atom number of 20 or less), or a group in which these are combined, and -CO- is preferable. 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 and 3 to 10 carbon atoms). An alicyclic hydrocarbon group, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination of these groups having 20 or less carbon atoms) may be bonded, and the R is an aliphatic hydrocarbon. A group (preferably an alkyl group) is preferable, and the number of carbon atoms of the aliphatic hydrocarbon group is preferably 1 to 5, more preferably 1 to 2.

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

In the polyoxyalkylene unit, the number of repetitions 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, still more preferably 15 or less. Is.

The number average molecular weight of the monomer (a2) 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 includes 2-hydroxyethyl (meth) acrylamide, the unsaturated carboxylic acid or its anhydride (a1), an oxyalkylene unit, and a monomer having a polymerizable unsaturated group (a2). May contain the monomer (a3) of.

Examples of the other monomer (a3) include a (meth) acrylic acid ester and a monoacrylic acid having a hydrophilic group (hydroxy group, imide group, cyano group, amino group, sulfonic acid group, quaternary ammonium group, etc.). Examples thereof include a metric, a (meth) acrylamide monomer other than 2-hydroxyethyl (meth) acrylamide, and other vinyl compounds.

As the (meth) acrylic acid ester, one kind or two or more kinds can be used, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, (meth). Isopropyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acrylate Neopentyl, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl 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 , (Meta) n-octadecyl acrylate, (meth) iso-octadecyl acrylate and other aliphatic (meth) acrylates; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopenta (meth) acrylate Alicyclic (meth) acrylic acid esters such as Nyl, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate; benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) ) Aromatic (meth) acrylic acid esters such as phenyl acrylate can be mentioned.

As the acrylic monomer having an imide group, one kind or two or more kinds can be used, and for example, (meth) acrylicimide, N-methylolmaleimide, N-hydroxyethylmaleimide, N-glycidylmaleimide, N- Examples thereof include 4-chloromethylphenylmaleimide and N-acetoxyethylmaleimide.

As the acrylic monomer having a cyano group, one kind or two or more kinds can be used, and for example, acrylonitrile, cyanomethyl acrylate, 2-cyanoethyl acrylate, cyanopropyl acrylate, 1-cyanomethyl ethyl acrylate, 2- Cyanopropyl Acrylate, 1-Cyanocyclopropyl Acrylate, 1-Cyanocycloheptyl Acrylate, 1,1-Dicyanoethyl Acrylate, 2-Cyanophenyl Acrylate, 3-Cyanophenyl Acrylate, 4-Cyanophenyl Acrylate, 3-Cyanobenzyl Acrylate, Examples thereof include 4-cyanobenzyl acrylate.

As the acrylic monomer having an amino group, one kind or two or more kinds can be used, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert-butylaminoethyl (meth). ) Acrylate, (meth) acrylic oxyethyltrimethylammonium chloride and the like.

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

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

Examples of the (meth) acrylamide monomer other than 2-hydroxyethyl (meth) acrylamide include (meth) acrylamide; (meth) acrylonitrile; (meth) acrylamide, N-methylol (meth) acrylamide, and N-methoxymethyl (meth). ) N-monosubstituted (meth) acrylamide monomers such as acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, etc .; N- (meth) acryloylmorpholine, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidin, N- (meth) acryloylpyrrolidin, N- (meth) acryloyl-4-piperidone, N, N-dimethyl (meth) acrylamide, N, N-diethyl Examples thereof include N, N-disubstituted (meth) acrylamide monomers such as (meth) acrylamide, N, N-methylenebis (meth) acrylamide, and N, N-dimethylaminopropyl (meth) acrylamide.

The content of the (meth) acrylamide monomer other than 2-hydroxyethyl (meth) acrylamide is preferably 50 parts by mass or less, more preferably 30 parts by mass, based on 100 parts by mass of 2-hydroxyethyl (meth) acrylamide. It is less than or equal to parts, more preferably 10 parts by mass or less, still more preferably 1 part by mass or less, and the lower limit is 0 parts by mass.

As the other vinyl compound, one kind or two or more kinds can be used, and examples thereof include styrene, α-methylstyrene, chlorostyrene, chloromethylstyrene, methylvinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

The content of the other monomer (a3) is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 3% by mass or less, and the lower limit is 0% by mass in the monomer component. %.

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 the radical polymerization method is preferable. At the time of polymerization, one kind or two or more kinds of polymerization initiators can be used. Specific examples of the polymerization initiator include 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride and 2,2'-azobis [2- (2-imidazolin-). 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-methylpropion amidine] 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'-Azobisisobutyamizin); hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, cumenhydroper Examples thereof include a peroxide initiator such as oxide; a persulfate initiator; a carbonyl initiator; a redox initiator, and the like, and an azo initiator is preferable.

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

The weight average molecular weight of the acrylic polymer (A) is 100,000 or more, preferably 150,000 or more, more preferably 220,000 or more, still more preferably 250,000 or more, and even more preferably 260,000. It may be 1,000,000 or less, 700,000 or less, and 500,000 or less, for example.

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

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

Examples of the polyol (b1) include polyether polyols, polyester polyols, polycarbonate polyols, polymer polyols of polyolefin polyols (b1-1); polyols having hydrophilic groups (b1-2); low molecular weight polyols (b1-3), and the like. Can be 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, 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 alkylene oxide is addition-polymerized. Can be mentioned.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, trimethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,4-. Butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, sorbitol, citrus sugar, aconit sugar, trimellitic acid, hemmellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanolamine, Examples thereof include 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, and tetrahydrofuran.

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.

Examples of the polyester polyol include 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 thereof include polyester polyols obtained by polymerization.

As the low molecular weight polyol used in the production of the polyester polyol, one kind or two or more kinds can be used, and for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1 , 3-Propanediol, Dipropylene glycol, Tripropylene glycol, 1,2-Butandiol, 1,3-Butandiol, 1,4-Butandiol, 2,3-Butandiol, 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- The molecular weight of 1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin, trimethylolpropane, ditrimethylolpropane, trimethylolpropane, pentaerythritol, etc. is 50. Examples thereof include aliphatic polyols having a temperature 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 kind or two or more kinds can be used, for example, an aliphatic polycarboxylic acid such as succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid; 1,4-cyclohexanedicarboxylic acid, cyclohexane. Alicyclic polycarboxylic acids such as tricarboxylic acids; aromatic polycarboxylic acids such as terephthalic acids, isophthalic acids, phthalic acids and naphthalenedicarboxylic acids; anhydrides or esterified products thereof.

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

As the carbonic acid ester, one kind or two or more kinds can be used, for example, an aliphatic carbonate, an alicyclic carbonate (hereinafter, including an alicyclic structure may be referred to as an "alicyclic"). Aromatic carbonates can be mentioned (hereinafter, the inclusion of aromatic structures may be collectively referred to as "aromatic"). Examples of the aliphatic carbonate include saturated aliphatic carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, ethyl-n-butyl carbonate and ethylisobutyl carbonate; ethylene carbonate, trimethylene carbonate, etc. 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, Examples thereof include unsaturated aliphatic carbonates such as 4-pentylene carbonate, 1,5-pentylene carbonate, 2,3-pentylene carbonate and 2,4-pentylene carbonate. Examples of the aromatic carbonate include diphenyl carbonate and dibenzyl carbonate.

As the polyhydric alcohol, one kind or two or more kinds can be used, and for example, ethylene glycol, propylene glycol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, diethylene glycol and diethylene glycol can be used. Linear or branched diols such as propylene glycol, triethylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol, hydrogenated bisphenol A; trimethylolmethane , Trimethylol propane, ditrimethylol propane, pentaerythritol, dipentaerythritol and other trifunctional or higher functional polyols.

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

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

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

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

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

Examples of the polyol having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. Of these, 2,2-dimethylolpropionic acid is preferable. Further, a polyester polyol having a carboxyl group obtained by reacting the polyol having a 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. Examples thereof include polyester polyols obtained by reacting with a low molecular weight polyol exemplified as one that can be used for producing a polyester polyol having.

It is preferable that a part or all of the anionic groups are neutralized by 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. Examples include oxides. From the viewpoint of improving the water dispersion stability of the urethane resin composition, the basic compound has a basic group / anionic group of the basic compound in the range of 0.5 to 3.0 (molar ratio). It is preferably used, and more preferably used in the range of 0.8 to 2.0 (molar ratio).

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

It is preferable that a part or all of the cationic group is neutralized with an acidic compound such as formic acid, acetic acid, propionic acid, succinic acid, glutaric acid, tartaric acid, and adipic acid.

Further, it is preferable that a 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, ethyl chloride and the like. Among these, it is preferable to use dimethyl sulfate.

Further, examples of the polyol having a nonionic group include a polyol having a polyoxyethylene structure and the like.

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, and a lower limit of about 50), and is, for example, 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, aliphatic polyols such as cyclohexanedimethanol; cyclobutanediol, cyclopentanediol, 1,4-cyclohexanediol, cycloheptandiol, cyclooctanediol, butylcyclohexanediol, Alicyclic polyols such as cyclohexanedimethanol, hydroxypropylcyclohexanol, dicyclohexanediol, hydrogenated bisphenyl A, 1,3-adamantandiol, 1,1'-bicyclohexylidenediol, cyclohexanetriol; bisphenol A, Examples thereof include bisphenol F, bisphenol AD, and aromatic polyols such as ethylene oxide and propylene oxide adduct thereof.

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

As the polyisocyanate (b2), one type or two or more types 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, and tetramethylxylylene diisocyanate. 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, cyclohexanediisocyanate, methylcyclohexanediisocyanate, dicyclohexyldimethylmethanediisocyanate, 2,2'-dimethyldicyclohexylmethanediisocyanate, and bis (isocyanatomethyl). 4-Isocyanato-n-butylidene) pentaerythritol, diisocyanate dimate, 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, etc. Therefore, it is preferably a saturated alicyclic polyisocyanate, and preferably a monocyclic (without a fused ring) alicyclic polyisocyanate. These alicyclic polyisocyanates can be used alone or in combination of two or more.

Examples of the aromatic polyisocyanate include phenylenediocyanate, 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 hydrophilic performance of the obtained coating film, it is preferable to contain an alicyclic polyisocyanate and an aromatic polyisocyanate, and more preferably to contain an alicyclic polyisocyanate.

The molar ratio (NCO / OH) of the isocyanate group contained in the polyisocyanate (b2) to the hydroxyl group contained in the polyol (b1) is preferably 1.05 or more, preferably 3 or less, more preferably. It is 2 or less.

The chain extender (b3) is a compound having two or more groups having an active hydrogen atom (preferably a substituted or unsubstituted amino group) in the molecule, and one or more 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-tolylene diamine, m-tolylene diamine, p-tolylene diamine; triamine compounds such as diethylenetriamine, triethylene Examples thereof include polyamine compounds having four or more amino groups such as tetramine and tetraethylenepentamine.

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

The terminal terminator (b4) is a compound having one group having an active hydrogen atom in the molecule (preferably a substituted or unsubstituted amino group or a hydroxyl group) or having a hydroxyl group and an active hydrogen atom in the molecule. Examples thereof include compounds having a group (preferably a substituted or unsubstituted amino group or hydroxyl group).

Examples of the compound 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. , Undecanol and other monoalcohol compounds; examples thereof include 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 a hydroxyl group) in the molecule include diol compounds such as propanediol, butanediol, pentanediol and hexanediol; Examples thereof include amino alcohol compounds such as ethanolamine and diethanolamine.

The end 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, with respect to 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) with the polyisocyanate (b2) with a chain extender (b3) and / or a terminal terminator (b4) used as needed. can do. The reaction temperature is preferably 50 to 150 ° C. Further, at the time of the reaction, a urethanization catalyst such as an organic tin compound may coexist.

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) to the urethane resin (B) is preferably 5/95 or more, more preferably 10/90 or more, and preferably 50/50. Hereinafter, it is more preferably 40/60 or less.

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

Examples of the aqueous medium (C) include water, an organic solvent miscible with water, and a mixture thereof. Examples of the organic solvent that can be mixed with water include alcohol solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, 1,2-propylene glycol and 1,3-butylene glycol; and ketone solvents such as acetone and methyl ethyl ketone; 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 Glycol ether solvent such as N-methyl-2-pyrrolidone, lactam solvent such as N-ethyl-2-pyrrolidone; amide solvent such as N, N-dimethylformamide and the like. These organic solvents that are miscible with water can be used alone or in combination of two or more.

Further, as the aqueous medium (C), considering safety and reduction of load on the environment, water alone or a mixture of water and an organic solvent miscible with water is preferable, and only water is more preferable.

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.

In addition to the acrylic polymer (A) and the aqueous medium (C), the aqueous resin composition contains a cross-linking agent, a plasticizer, an antistatic agent, a wax, a surfactant, a light stabilizer, and a flow, if necessary. It may also contain other additives such as modifiers, dyes, leveling agents, rheology control agents, UV absorbers, antioxidants, photocatalytic compounds, inorganic pigments, organic pigments, extender pigments and the like.

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

Further, by using the above-mentioned surfactant, the compounding stability of the urethane resin composition of the present invention can be further improved. When a surfactant is used, it is preferable to use it in a range of 20 parts by mass or less with respect to 100 parts by mass of the urethane resin (A), as much as possible, because the adhesion of the obtained coating film to the base material can be maintained. It is preferable not to use it.

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

The coating agent composed of the aqueous resin composition is also included in the technical scope of the present invention. Examples of the base material of the coating agent include metals, various plastics and films thereof, glass, paper, wood and the like.

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

As the plastic base material, acrylonitrile-butadiene-styrene resin (ABS resin) and polycarbonate resin (PC) are generally used as materials used for plastic molded products such as mobile phones, home appliances, automobile interior / exterior materials, and OA equipment. Resin), ABS / PC resin, polystyrene resin (PS resin), polymethylmethacrylate resin (PMMA resin), acrylic resin, polypropylene resin, polyethylene resin, etc. Examples of the plastic film base material include polyethylene terephthalate film and polyester film. , Polyethylene film, polypropylene film, TAC (triacetyl cellulose) film, polycarbonate film, polyvinyl chloride film and the like can be used.

The coating agent is, for example, aluminum fins; building members such as outer walls and roofs; civil engineering members such as guard rails, soundproof walls and drainage ditches; home appliances; industrial machinery; automobile exterior materials; goggles; anti-fog film sheets, anti-fog glass. Anti-fog material such as; mirror; can be suitably used for surface coating of various articles such as medical instruments. Articles having a coating film 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 base material, drying and curing it. 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 a dipping method. The drying may be natural drying at room temperature, but it may also be heat-dried. The heat drying is usually carried out at 40 to 250 ° C. for a time of about 1 to 600 seconds.

The aqueous 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.

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

[Measurement method of 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 ID x 300 mm L. x 2)
Guard column: Shodex OHpak SB-G
(4.6 mm ID 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. lcm

(Standard sample)
Showa Denko KK "Shodex Pullulan P-800"
Showa Denko KK "Shodex Pullulan P-400"
Showa Denko KK "Shodex Pullulan P-200"
Showa Denko KK "Shodex Pullulan P-100"
Showa Denko KK "Shodex Pullulan P-50"
Showa Denko KK "Shodex Pullulan P-20"
Showa Denko KK "Shodex Pullulan P-10"
Showa Denko KK "Shodex Pullulan P-5"

(Synthesis example (A-1))
In a four-necked flask equipped with a thermometer, a stirrer, a reflux cooling tube and a dropping device, ion-exchanged water and isopropyl alcohol were charged as polymerization solvents in a nitrogen atmosphere so as to make a total of 350 parts by mass, and 2-hydroxyethyl acrylamide was charged. 50 parts by mass (hereinafter referred to as "HEAA"), 48 parts by mass of methoxypolyethylene glycol acrylate ("AM-90G" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., average number of moles of oxyethylene group added is 9 mol), acrylic acid (hereinafter referred to as "HEAA") , "AA") 1 part by mass was charged. Next, 0.05 parts by mass of an azo-based polymerization initiator (“VA-044” manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise, and the mixture was held at 50 ° C. for radical polymerization to carry out radical polymerization of the acrylic polymer (A-1). The composition was obtained. The weight average molecular weight of the composition of the obtained acrylic polymer (A-1) was 340,000, and the non-volatile content was 20% by mass.

(Comparative synthesis example (1))
In the same manner as in Synthesis Example 1, except that in Synthesis Example (A-1), 50 parts by mass of 2,2-dimethylacrylamide (hereinafter referred to as “DMAA”) was used instead of 50 parts by mass of HEAA. The composition of the comparative acrylic polymer (1) was obtained.

(Synthesis example (B-1))
A number average molecular weight of 1,200 obtained by reacting ethylene glycol, neopentyl glycol, terephthalic acid, isophthalic acid, and adipic acid in a nitrogen-substituted container equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer. Molecular by charging 69.8 parts by mass of polyester polyol, 2.7 parts by mass of 2,2-dimethylol propionic acid (DMPA), 25 parts by mass of dicyclohexylmethane diisocyanate (H12MDI) and 65 parts by mass of methyl ethyl ketone and reacting them at 70 ° C. An organic solvent solution of a urethane prepolymer having an isocyanate group at the terminal was obtained.

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

(Example 1, Comparative Example 1)
In a four-necked flask equipped with a thermometer, a stirrer, a reflux cooling tube, and a dropping device, a solution of the acrylic polymer (A) and the urethane resin (B) shown in the table below was added to the acrylic polymer (A). The mass ratio of the non-volatile content of the urethane resin (B) ((A) / (B)) is 15/85, and the aqueous medium with respect to a total of 10 parts by mass of the non-volatile content of the acrylic polymer (A) and the urethane resin (B). An aqueous dispersion was obtained by adding 30 parts by mass of the ion-exchanged water as (C). The aqueous dispersion was distilled under reduced pressure to obtain an aqueous resin composition (1) and a comparative composition (1) having a non-volatile content of 25% by mass.

[Creation of test piece]
The aqueous resin composition (1) and the composition of the comparative composition (1) obtained in Example 1 and Comparative Example 1 were applied to an aluminum plate to a thickness of 1 μm, dried under the conditions shown in Table 1, and tested pieces. It was created.

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

[Evaluation of hydrophilicity retention (cycle test)]
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 after 8 seconds was measured. The wet condition was to immerse in water at 25 ° C. for 2 minutes, and the dry condition was to hold it at 40 ° C. for 6 minutes.

[Evaluation of hydrophilicity retention (processing oil test)]
After immersing the test piece in the processing oil, the test piece was leaned against the test piece for 10 minutes to drain the oil. Next, it was dried at 150 ° C. for 5 minutes, and the contact angle of the coated surface of the obtained test piece was measured.

The evaluation results are shown in Table 1. If the water contact angle is less than 40 °, it is considered to have good hydrophilicity.

Example 1 was an example of the present invention, and the hydrophilicity persistence was good. Comparative Example 1 was an example in which 2,2-dimethylacrylamide was used instead of 2-hydroxyethyl (meth) acrylamide, and the hydrophilicity persistence after the processing oil test was poor.

Claims (6)

1. The acrylic polymer (A) contains a urethane resin (B) and an aqueous medium (C), and the acrylic polymer (A) contains 2-hydroxyethylacrylamide, an unsaturated carboxylic acid or an anhydride thereof, and the like. An aqueous resin composition formed from a monomer component containing at least a polyoxyalkylene unit and a monomer having a polymerizable unsaturated group, and having a weight average molecular weight of 100,000 or more.
2. The aqueous resin composition according to claim 1, wherein the unsaturated carboxylic acid or its anhydride is methacrylic acid.
3. The aqueous resin composition according to claim 1 or 2, wherein the number average molecular weight of the monomer having a polyoxyalkylene unit and a polymerizable unsaturated group is 200 or more and 1,500 or less.
4. Any one of claims 1 to 3, 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. The aqueous resin composition according to the above item.
5. A coating agent comprising the aqueous resin composition according to any one of claims 1 to 4.
6. An article having a coating film of the coating agent according to claim 5.