Hydrophilization treatment composition

Abstract

The present invention addresses the problem of providing a hydrophilization treatment composition which is capable of forming a hydrophilized layer that has good hydrophilicity, water sliding properties, and hydrophilicity sustainability. A hydrophilization treatment composition according to the present invention contains a copolymer (A) which has: at least one constituent unit (A1) that is selected from among a constituent unit (A11) which is derived from a polymerizable monomer having a carboxyl group and a constituent unit (A12) which is derived from a polymerizable monomer having a hydroxyl group; and a constituent unit (A2) that is derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond.

Description

Hydrophilic treatment composition

[0001] The present invention relates to a hydrophilic treatment composition.

[0002] Heat exchangers have heat exchange plates, such as aluminum fins, that exchange heat between the heat transfer medium and the air. When the heat exchanger is in operation, moisture in the air can condense on the aluminum fin surface. If this condensed water turns into droplets and forms bridges between the fins, problems such as increased power consumption due to ventilation resistance and water droplet scattering can occur. To prevent such bridges caused by condensed water, the fin surface is often treated to be hydrophilic.

[0003] A known hydrophilic treatment involves applying a resin composition containing hydrophilic particles to the surface of a fin material to form a hydrophilic coating. Conventionally, inorganic particles such as silica and organic particles such as acrylic particles have been used as hydrophilic particles. Patent Documents 1 and 2 describe the use of hydrophilic crosslinked polymer microparticles composed of a copolymer of (a) 2 to 50 wt% of a hydrophilic monomer having a polymerizable double bond and a polyoxyalkylene chain or a polyvinylpyrrolidone chain, (b) 20 to 97 wt% of a (meth)acrylamide monomer, (c) 1 to 30 wt% of a crosslinkable unsaturated monomer, (d) 2 to 50 wt% of a carboxyl group-containing polymerizable unsaturated monomer, and (e) 0 to 50 wt% of other polymerizable monomers.

[0004] Furthermore, if the aluminum fin surface remains wet due to condensed water, it can cause various problems, such as reduced heat exchange efficiency, corrosion of the aluminum fin, bacterial growth, and frost formation. To solve these problems, it is important to facilitate drainage of condensed water from the aluminum fin surface, i.e., to increase the water sliding property of the aluminum fin surface. It is also known to treat the aluminum fin surface with a water-repellent treatment to improve the drainage property (water sliding property) of this condensed water. For example, Patent Document 3 discloses that a superwater- and oil-repellent heat exchanger component with excellent water sliding properties can be obtained by providing a plurality of confetti-shaped protrusions made of silica or the like on the surface of a substrate, and then forming a water-repellent, oil-repellent, and antifouling thin film on the surface of the substrate with the confetti-shaped protrusions. Patent Document 4 also discloses that a heat exchanger component with excellent water repellency and water sliding properties can be obtained by applying a structure having a water-sliding water-repellent layer containing a polymer having a polyethyleneimine skeleton, a fluorine-containing compound, and silica to a substrate.

[0005] On the other hand, Patent Document 5 describes that by using a treatment agent obtained by blending a specific water-soluble resin (A), colloidal silica (B), organoalkoxysilane and / or its hydrolyzate (C), a crosslinking agent (D) capable of crosslinking with the water-soluble resin (A), and water (E) in a predetermined ratio as a surface treatment agent for a heat exchanger made of an aluminum-containing metal, it is possible to make the aluminum fin surface hydrophilic, thereby preventing bridging due to condensed water and also improving drainage properties.

[0006] Japanese Patent Application Laid-Open No. 9-87576 Japanese Patent Application Laid-Open No. 2000-328038 Japanese Patent Application Laid-Open No. 2013-92289 International Publication No. 2020 / 213485 International Publication No. 2014 / 147782

[0007] The present invention aims to solve the following first and / or second problems. (First Problem) Surface hydrophilicity (initial hydrophilicity) is sometimes required for a variety of applications, including but not limited to the hydrophilization of fin materials in heat exchangers and coatings applied to their surfaces. There are cases in which high hydrophilicity (initial hydrophilicity) of a coating film immediately after coating film formation and good drainage properties (water sliding) of droplets are required. Therefore, the first problem of the present invention is to provide a new hydrophilic treatment composition capable of forming a hydrophilized layer (for example, a coating film) with good hydrophilicity and water sliding properties.

[0008] (Second Objective) The hydrophilic coating film is required to have enhanced hydrophilicity immediately after formation (initial hydrophilicity) as well as to maintain this hydrophilicity. In particular, the fin material of a heat exchanger will, over the course of long-term use, repeatedly go through a wet state in which condensed water is present on the surface of the fin material and a dry state in which the condensed water evaporates. Therefore, a hydrophilic layer such as a hydrophilic coating film applied to the fin material of a heat exchanger may be required to maintain its hydrophilicity even after repeated adhesion and drying of condensed water. Therefore, a second object of the present invention is to provide a hydrophilization treatment composition capable of forming a hydrophilic layer (e.g., a coating film) that has good hydrophilicity maintenance even after repeated adhesion and drying of low-ion water such as pure water (hereinafter sometimes referred to as "after wet / dry cycles").

[0009] The present invention aims to solve at least one of the first and second problems, and in a preferred embodiment, aims to solve both the first and second problems.

[0010] As a result of extensive research aimed at solving the above problems, the present inventors have found that the use of a specific polymer can enhance both hydrophilicity and water slippage, and further that the use of the polymer can enhance the persistence of hydrophilicity after wet / dry cycles.

[0011] That is, the present invention includes the following inventions. [1] A hydrophilic treatment composition characterized by containing a copolymer (A) having at least one structural unit (A1) selected from the structural unit (A11) derived from a polymerizable monomer having a carboxyl group and the structural unit (A12) derived from a polymerizable monomer having a hydroxyl group, and a structural unit (A2) derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond. [2] The hydrophilic treatment composition according to [1], in which the hydrocarbon group in the structural unit (A2) is an aliphatic hydrocarbon group. [3] The hydrophilic treatment composition according to [1] or [2], in which the structural unit (A2) is derived from a monomer represented by the following formula: (In the formula, R １ , R ２ R each independently represents a hydrogen atom or a methyl group. ３ represents an alkylene group having 1 to 4 carbon atoms. ４represents an alkylene group having 2 to 4 carbon atoms. a is 0 or 1, and b represents the average number of moles added of 2 to 500.) [4] The hydrophilic treatment composition according to any one of [1] to [3], further comprising hydrophilic particles (B) having at least one group selected from an acid group, a hydroxyl group, a polyoxyalkylene chain, and a polyvinylpyrrolidone chain. [5] The hydrophilic treatment composition according to any one of [1] to [4], further comprising a crosslinking agent. [6] The hydrophilic treatment composition according to [5], wherein the crosslinking agent is a crosslinking agent having two or more oxazoline groups per molecule. [7] The hydrophilic treatment composition according to [4], wherein the volume average particle diameter of the hydrophilic particles is 10 nm to 10 μm. [8] The hydrophilic treatment composition according to any one of [1] to [7], wherein the object to be hydrophilically treated is a fin of a heat exchanger. [9] The hydrophilic treatment composition according to any one of [1] to [8], wherein the structural unit (A11) derived from a polymerizable monomer having a carboxyl group is a structural unit derived from an unsaturated monocarboxylic acid or a salt thereof.

[10] The hydrophilic treatment composition according to [9], wherein the unsaturated monocarboxylic acid or a salt thereof is acrylic acid, methacrylic acid, or a salt thereof.

[11] The hydrophilic treatment composition according to any one of [1] to

[10] , wherein the structural unit (A12) derived from a polymerizable monomer having a hydroxyl group is a structural unit derived from a (meth)acrylic acid hydroxyalkyl ester.

[12] The hydrophilic treatment composition according to any one of [1] to

[11] , wherein the structural unit (A2) is a structural unit derived from an ethylene oxide adduct of 2-methyl-2-propen-1-ol or an ethylene oxide adduct of 3-methyl-3-buten-1-ol.

[13] The hydrophilic treatment composition according to any one of [1] to

[12] , wherein the content of the structural unit (A2) is 30 to 99 parts by mass per 100 parts by mass of the total of the structural unit (A1) and the structural unit (A2).

[14] The hydrophilic treatment composition according to any one of [1] to

[13] , wherein the total content of the structural unit (A1) and the structural unit (A2) is 70 to 100 parts by mass per 100 parts by mass of the copolymer (A).

[15] The hydrophilic treatment composition according to [4], wherein the hydrophilic particles (B1) contain a hydrophilic polymer (b2) having an acid group and a hydroxyl group.

[0012]

[16] A heat exchanger fin having a hydrophilized layer formed on its surface, the hydrophilized layer comprising a copolymer (A) having at least one structural unit (A1) selected from the structural unit (A11) derived from a polymerizable monomer having a carboxyl group and the structural unit (A12) derived from a polymerizable monomer having a hydroxyl group, and a structural unit (A2) derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond.

[17] The fin according to

[16] , wherein the thickness of the hydrophilized layer is 0.1 to 80 μm.

[0013] The present invention can achieve the following first and / or second effects. First effect: By using the hydrophilic treatment composition of the present invention, it is possible to impart hydrophilicity and water-slip property to the obtained hydrophilic layer. Second effect: By using the hydrophilic treatment composition of the present invention, it is possible to improve the hydrophilicity sustainability of the obtained hydrophilic layer after wet / dry cycles.

[0014] FIG. 1 is a schematic diagram showing a method for measuring the sliding angle.

[0015] [Hydrophilic Treatment Composition] The hydrophilic treatment composition of the present invention contains a copolymer (A) having at least one structural unit (A1) selected from structural units (A11) derived from polymerizable monomers having a carboxyl group and structural units (A12) derived from polymerizable monomers having a hydroxyl group, and a structural unit (A2) derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond. The copolymer (A) constituting the hydrophilic treatment composition of the present invention is able to exhibit excellent hydrophilic properties (initial hydrophilicity, sustained hydrophilicity after wet / dry treatment, and water slippage) due to the carboxyl and / or hydroxyl groups contained in the structural unit (A1) and the polyoxyalkylene group ether-bonded to a specific hydrocarbon group contained in the structural unit (A2). [Structural Unit (A1)] The structural unit (A1) of the present invention is at least one selected from structural units (A11) derived from polymerizable monomers having a carboxyl group and structural units (A12) derived from polymerizable monomers having a hydroxyl group.

[0016] As used herein, a "structural unit derived from a polymerizable monomer" refers to a structural unit having the same structure as the structure formed by polymerizing a specified monomer, and typically has a structure in which the carbon-carbon double bond contained in the specified monomer is replaced with a carbon-carbon single bond and two bonds bonded to each carbon. Note that a structural unit derived from a specified monomer does not necessarily have to be a structural unit formed by actually polymerizing the specified monomer; even a structural unit formed by a method other than polymerizing the specified monomer (for example, a structural unit formed via a reaction such as hydrolysis or neutralization after polymerization) is included in the structural unit derived from the specified monomer, as long as it has the same structure as the structure formed by polymerizing the specified monomer.

[0017] [Structural Unit (A11) Derived from Polymerizable Monomer Having a Carboxyl Group] The number of carboxyl groups contained in the polymerizable monomer having a carboxyl group is preferably 1 to 3, and more preferably 1. The polymerizable group contained in the polymerizable monomer having a carboxyl group is preferably an ethylenically unsaturated bond-containing group such as a vinyl group, an allyl group, or a (meth)acryloyl group, and more preferably a (meth)acryloyl group.

[0018] Examples of the polymerizable monomer having a carboxyl group include a carboxyl group-containing monofunctional monomer and a salt of a carboxyl group-containing monofunctional monomer.

[0019] Specific examples of the carboxyl group-containing monofunctional monomer include unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and among these, unsaturated monocarboxylic acids are preferred, (meth)acrylic acid is more preferred, and acrylic acid is particularly preferred.

[0020] Examples of the salt of the carboxyl group-containing monofunctional monomer include alkali metal salts of the carboxyl group-containing monofunctional monomer and ammonium salts of the carboxyl group-containing monofunctional monomer. Salts of unsaturated monocarboxylic acids are preferred, and salts of acrylic acid are more preferred. Specific examples of alkali metal atoms and ammonium atoms that form salts with the carboxyl group-containing monofunctional monomer in the salt of the carboxyl group-containing monofunctional monomer are as follows:

[0021] Examples of the alkali metal atom include lithium, sodium, and potassium, with sodium and potassium being preferred, and sodium being more preferred.

[0022] Ammonium is NH ４＋ The organic ammonium is not limited to, but includes organic ammonium. The organic ammonium includes tetraalkylammonium such as tetramethylammonium and tetrabutylammonium (preferably tetra C １－１０ ammonium (primary to tertiary ammonium) formed by protonating an amine. Examples of the amine include trialkylamines (preferably triC) such as trimethylamine, triethylamine, and tributylamine. １－１０ alkylamines); hydroxyalkylamines such as monoethanolamine, diethanolamine, and triethanolamine (preferably mono-, di-, or tri(hydroxy C １－１０ That is, ammonium includes NH ４＋ ammonium, primary to quaternary ammonium, and tetraalkylammonium such as tetramethylammonium and tetrabutylammonium (preferably tetra C １－１０ trialkylammonium (preferably triC alkylammonium), trimethylammonium, triethylammonium, tributylammonium, etc. １－１０ hydroxyalkylammonium (preferably mono-, di- or tri(hydroxy C alkyl ammonium) such as monoethanolammonium, diethanolammonium, triethanolammonium, １－１０alkyl)ammonium), or NH ４＋ is preferred.

[0023] [Structural Unit (A12) Derived from Polymerizable Monomer Having a Hydroxyl Group] The number of hydroxyl groups contained in the polymerizable monomer having a hydroxyl group is preferably 1 to 3, and more preferably 1. The polymerizable group contained in the polymerizable monomer having a hydroxyl group is preferably an ethylenically unsaturated bond-containing group such as a vinyl group, an allyl group, or a (meth)acryloyl group, and more preferably a (meth)acryloyl group.

[0024] Specific examples of the polymerizable monomer having a hydroxyl group include (meth)acrylic acid hydroxyalkyl esters such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and hydroxypentyl (meth)acrylate; 3-(meth)allyloxy-1,2-dihydroxypropane, 1-allyloxy(meth)acrylic acid C １－８ Hydroxyalkyl esters are preferred, and (meth)acrylic acid C １－４ Hydroxyalkyl esters are more preferred.

[0025] [Structural Unit (A2)] The structural unit (A2) of the present invention is a structural unit derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond.

[0026] [Polyoxyalkylene Group] The polyoxyalkylene group preferably has a structure represented by the following formula: In the formula, R ４ is C ｍ H ２ｍ The alkylene group may be either linear or branched, but is preferably linear. ４may be the same or different in the b repeating units. m is preferably an integer of 2 to 4, more preferably 2 or 3, and even more preferably 2. Examples of oxyalkylene groups having 2 to 4 carbon atoms include oxyethylene groups, oxypropylene groups, and oxybutylene groups. b represents the average number of moles of oxyalkylene groups added, and is preferably 2 to 500, more preferably 5 to 300, and even more preferably 10 to 200. R ５ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. R ５ is preferably a hydrogen atom.

[0027] [Hydrocarbon Group Having a Polymerizable Double Bond] The hydrocarbon group having a polymerizable double bond has at least one polymerizable double bond per molecule. The number of carbon atoms in the hydrocarbon group having a polymerizable double bond is not particularly limited, but may be 2 to 20, preferably 2 to 10, and more preferably 2 to 5. The hydrocarbon group having a polymerizable double bond may be linear, branched, or cyclic, and is preferably an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, and more preferably an aliphatic hydrocarbon group. The hydrocarbon group having a polymerizable double bond preferably has a substituent linked to a polyoxyalkylene group via an ether bond.

[0028] Examples of the aliphatic hydrocarbon group having a polymerizable double bond include alkenyl groups such as vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, hexadecenyl, and icosenyl groups, and preferred are vinyl, 2-propenyl (allyl), 2-methyl-2-propenyl (methallyl), and 3-methyl-3-butenyl (isoprenyl).

[0029] Examples of the alicyclic hydrocarbon group having a polymerizable double bond include cycloalkenyl groups such as a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, a cyclononadecaenyl group, and a cyclodecaenyl group.

[0030] Examples of the aromatic hydrocarbon group having a polymerizable double bond include alkenylaryl groups such as a styrene group, a vinylphenyl group, an allylbenzene group, an isoprenylbenzene group, and a chlorostyrene group.

[0031] Of the above, the hydrocarbon group having a polymerizable double bond is preferably an aliphatic hydrocarbon group, and particularly preferably an aliphatic hydrocarbon group having 4 or 5 carbon atoms.

[0032] The structural unit (A2) is preferably a structural unit derived from a monomer represented by the following formula: In the formula, R １ , R ２ R each independently represents a hydrogen atom or a methyl group. ３ represents an alkylene group having 1 to 4 carbon atoms. Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a propylene group, and a butylene group. R ４ represents an alkylene group having 2 to 4 carbon atoms. a is 0 or 1, and b represents the average number of moles of oxyalkylene groups added, preferably a number from 2 to 500, more preferably 5 to 300, and even more preferably 10 to 200.

[0033] Specific examples of the structural unit represented by the above formula include the following: ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of vinyl alcohol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-propen-1-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 3-buten-1-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 4-penten-1-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 5-hexen-1-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-propen-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-methyl-2-propen-1-ol (methallyl alcohol); Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 3-methyl-3-buten-1-ol (isoprenol); Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 4-methyl-4-penten-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 5-methyl-5-hexen-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 1-propen-1ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-buten-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 3-penten-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 4-hexen-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 5-hepten-1-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-buten-2-ol; ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-methyl-2-buten-1-ol;Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 3-methyl-3-penten-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 4-methyl-4-hexen-1-ol; Ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 5-methyl-5-hepten-1-ol; Of the above, preferred are ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 2-methyl-2-propen-1-ol (methallyl alcohol); and ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of 3-methyl-3-buten-1-ol (isoprenol), with the ethylene oxide adducts of 2-methyl-2-propen-1-ol and 3-methyl-3-buten-1-ol being more preferred.

[0034] The copolymer (A) may have one or more types of structural units corresponding to the structural unit (A1) and one or more types of structural units corresponding to the structural unit (A2).

[0035] From the standpoint of further improving hydrophilicity, the content of the structural unit (A2) is preferably 30 to 99 parts by mass, more preferably 50 to 95 parts by mass, and even more preferably 55 to 95 parts by mass, per 100 parts by mass of the total of the structural unit (A1) and the structural unit (A2).

[0036] The total content of the structural unit (A1) and the structural unit (A2) is preferably 70 to 100 parts by mass, more preferably 75 to 100 parts by mass, and even more preferably 80 to 100 parts by mass, per 100 parts by mass of copolymer (A), and may even be 100 parts by mass.

[0037] The weight average molecular weight of the copolymer (A) is preferably 2,000 to 1,000,000, more preferably 3,000 to 500,000, and even more preferably 4,000 to 250,000. The weight average molecular weight is measured by GPC (gel permeation chromatography) under the conditions described in the examples.

[0038] The copolymer (A) may contain one or more structural units (hereinafter, "other structural units (A3)") derived from monomers having a carbon-carbon double bond (hereinafter, "other monomers") other than the structural units (A1) and (A2).

[0039] The other monomers are not particularly limited as long as they can be copolymerized with the structural units (A1) and (A2), and examples thereof include 3-(meth)allyloxy-2-hydroxypropanesulfonic acid, 2-(meth)allyloxyethylenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid, α-methyl-p-styrenesulfonic acid, vinylsulfonic acid, vinylsulfamic acid, (meth)allyl sulfonic acid, isoprenesulfonic acid, 4-(allyloxy)benzenesulfonic acid, Unsaturated sulfonic acids and salts thereof, such as 1-methyl-2-propene-1-sulfonic acid, 1,1-dimethyl-2-propene-1-sulfonic acid, 3-butene-1-sulfonic acid, 1-butene-3-sulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamido-2-phenylpropanesulfonic acid, and 2-((meth)acryloyloxy)ethanesulfonic acid; N-vinyl lactams, such as N-vinylpyrrolidone Monomers: (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-nonyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylamide, N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, and N,N-dimethyl N-substituted or unsubstituted (meth)acrylamides such as (meth)acrylamide; vinylaryl monomers such as styrene, α-methylstyrene, vinyltoluene, indene, vinylnaphthalene, phenylmaleimide, and vinylaniline; alkenes such as ethylene, propylene, butadiene, isobutylene, and octene; vinyl carboxylates such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; vinyl ethylene carbonate and its derivatives;Examples include unsaturated amines such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, vinylpyridine, vinylimidazole, and salts or quaternized products thereof; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile;

[0040] The content of the structural unit (A3) derived from other monomers in the copolymer (A) is, for example, 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less or 10% by mass or less, and even more preferably 5% by mass or less or 3% by mass or less.

[0041] The hydrophilic treatment composition preferably further contains a crosslinking agent. By including a crosslinking agent, the strength of the hydrophilic layer containing the hydrophilic treatment composition of the present invention can be increased. Furthermore, by including a crosslinking agent, the durability of the hydrophilic layer is improved, resulting in improved hydrophilicity retention and improved water slippage of the hydrophilic layer after heat cycling, as shown in the examples described below. The crosslinking agent may be used alone or in combination of two or more. The crosslinking agent is preferably a compound having two or more groups per molecule that can react with the polar functional group of the hydrophilic treatment composition. Examples of groups that can react with polar functional groups include epoxy groups, oxazoline groups, carbodiimide groups, isocyanate groups, etc., and may be selected appropriately depending on the hydrophilic treatment composition to be used.

[0042] Examples of the crosslinking agent include at least one selected from melamine resin, urea resin, polyaldehyde compound, phenolic resin, polyepoxy compound, blocked polyisocyanate compound, metal compound (metal salt, metal complex, metal oxide, metal hydroxide, etc.), oxazoline compound, carbodiimide compound, hydroxyalkylamide compound, hydrazide compound, semicarbazide compound, and silicate compound. In particular, it is preferable to use a crosslinking agent having two or more oxazoline groups in one molecule, and by combining it with the hydrophilic treatment composition of the present invention, the above-mentioned durability improvement effect tends to be further enhanced.

[0043] As a crosslinking agent having two or more oxazoline groups per molecule, a water-soluble oxazoline compound is preferred from the viewpoint of excellent crosslinking performance, and an oxazoline group-containing polymer is also preferred. The oxazoline group-containing polymer can be produced by a conventionally known production method. For example, a method of polymerizing a monomer component containing one or more addition-polymerizable oxazolines, or an addition-polymerizable oxazoline and a monomer copolymerizable with the addition-polymerizable oxazoline, can be mentioned.

[0044] Examples of the addition-polymerizable oxazoline include compounds having a polymerizable unsaturated group and an oxazoline group in the molecule, such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. Preferred monomers copolymerizable with the addition-polymerizable oxazoline are monomers that do not have a functional group reactive with the oxazoline group and are copolymerizable with the addition-polymerizable oxazoline. For example, (meth)acrylic monomers such as alkyl (meth)acrylates; styrene-based monomers such as styrene, α-methylstyrene, and chloromethylstyrene; vinyl-based monomers such as vinyl acetate, vinyl chloride, and vinyl benzoate; acrylonitrile; (meth)acrylamide-based monomers such as acrylamide; and olefin-based monomers such as ethylene and propylene.

[0045] Among the oxazoline group-containing polymers, water-soluble oxazoline group-containing polymers are preferred, and can be produced by the same method as the above-mentioned method for producing the oxazoline group-containing polymer. Examples of the water-soluble oxazoline group-containing polymer include polymers having a main chain of a (meth)acrylic resin or the like and containing oxazoline groups in side chains.

[0046] Commercially available oxazoline group-containing polymers can also be used, including, for example, water-soluble polymers such as EPOCROS WS-500 and EPOCROS WS-700, and emulsion polymers such as EPOCROS K-2010E, EPOCROS K-2020E, and EPOCROS K-2035E, all of which are manufactured by Nippon Shokubai Co., Ltd.

[0047] The content of the crosslinking agent is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, and even more preferably 5 to 30 parts by mass, relative to 100 parts by mass of the copolymer (A).

[0048] The hydrophilic treatment composition may further contain a solvent. By containing a solvent, the coating properties of the hydrophilic treatment composition become good. As the solvent, an aqueous solvent is preferable from the viewpoint of reducing the environmental load. The aqueous solvent may be water alone or a mixed solvent of water and a water-miscible organic solvent. Typically, the aqueous solvent refers to a solvent having a water content of more than 50% by volume. As the water, ion-exchanged water (deionized water), distilled water, pure water, etc. can be used. As the water-miscible organic solvent, an organic solvent that can be uniformly mixed with water (for example, C １－４ Alkyl alcohols and other lower alcohols can be used.

[0049] The content of the solvent in the hydrophilic treatment composition may be 0% by mass, is preferably 0.1% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and particularly preferably 80% by mass or more, and is preferably 99.9% by mass or less, and more preferably 99% by mass or less.

[0050] [Method for producing copolymer (A)] The production of copolymer (A) of the present invention is not particularly limited, but it can be produced by polymerizing monomer components, specific examples and preferred examples of which are as described above. The proportion of each structural unit in the copolymer obtained by the polymerization reaction can be calculated based on the proportion of each monomer used as a reaction raw material and the remaining amount of monomer measured by high performance liquid chromatography.

[0051] In producing the copolymer, a chain transfer agent can be used to adjust the molecular weight of the resulting polymer. Examples of the chain transfer agent include thiol-based chain transfer agents such as mercaptoethanol, thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, and 2-mercaptoethanesulfonic acid; secondary alcohols such as isopropyl alcohol; and hydrophilic chain transfer agents such as lower oxides and salts of phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionous acid, metabisulfite, and salts thereof (sodium sulfite, sodium hydrogen sulfite, sodium dithionite, sodium metabisulfite, etc.).

[0052] A hydrophobic chain transfer agent can also be used as the chain transfer agent. Suitable examples of the hydrophobic chain transfer agent include thiol-based chain transfer agents having a hydrocarbon group with three or more carbon atoms, such as butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, and octyl 3-mercaptopropionate. Furthermore, in order to adjust the molecular weight of the copolymer, it is also effective to use a monomer with high chain transfer properties, such as (meth)allylsulfonic acids (salts).

[0053] The amount of the chain transfer agent used may be appropriately determined, but is preferably 0.1 mol or more, more preferably 0.25 mol or more, and even more preferably 0.5 mol or more, relative to 100 mol of the total amount of the monomer components, and is preferably 20 mol or less, more preferably 15 mol or less, and even more preferably 10 mol or less.

[0054] The polymerization reaction can be carried out by a method such as solution polymerization or bulk polymerization, using a radical polymerization initiator as necessary. Solution polymerization can be carried out batchwise or continuously, or a combination thereof, and examples of the solvent used in this case include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, and n-hexane; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; and cyclic ether compounds such as tetrahydrofuran and dioxane. Among these, polymerization by aqueous solution polymerization is preferred.

[0055] When the aqueous solution polymerization is carried out, a water-soluble polymerization initiator is used as the radical polymerization initiator, for example, a persulfate such as ammonium persulfate, sodium persulfate, or potassium persulfate; hydrogen peroxide; azoamidine compounds such as 2,2'-azobis-2-methylpropionamidine hydrochloride; cyclic azoamidine compounds such as 2,2'-azobis-2-(2-imidazolin-2-yl)propane hydrochloride; or azonitrile compounds such as 2-carbamoylazoisobutyronitrile. In this case, an accelerator such as an alkali metal sulfite such as sodium hydrogensulfite, metabisulfite, sodium hypophosphite, Fe(II) salts such as Mohr's salt, sodium hydroxymethanesulfinate dihydrate, hydroxylamine hydrochloride, thiourea, L-ascorbic acid (salt), or erythorbic acid (salt) may also be used in combination. Among these, persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, and combinations of hydrogen peroxide with an accelerator such as L-ascorbic acid (salt) are preferred. These radical polymerization initiators and accelerators may be used alone or in combination of two or more. Furthermore, when solution polymerization is performed using a lower alcohol, an aromatic or aliphatic hydrocarbon, an ester compound, or a ketone compound as the solvent, or when bulk polymerization is performed, peroxides such as benzoyl peroxide, lauroyl peroxide, and sodium peroxide; hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; and azo compounds such as azobisisobutyronitrile are used as radical polymerization initiators. In this case, accelerators such as amine compounds can also be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, the radical polymerization initiators or combinations of radical polymerization initiators and accelerators described above can be appropriately selected and used.

[0056] The amount of the radical polymerization initiator used is preferably 0.001 mol or more, more preferably 0.01 mol or more, even more preferably 0.1 mol or more, particularly preferably 0.2 mol or more, relative to 100 mol of the total amount of the monomer components, and is preferably 20 mol or less, even more preferably 10 mol or less, particularly preferably 7 mol or less, and most preferably 5 mol or less.

[0057] In the polymerization reaction, polymerization conditions such as polymerization temperature are appropriately determined depending on the polymerization method, solvent, polymerization initiator, and chain transfer agent used, but the polymerization temperature is preferably 0°C or higher and 150°C or lower, more preferably 30°C or higher, and even more preferably 50°C or higher, and more preferably 120°C or lower, and even more preferably 100°C or lower.

[0058] The method for adding each monomer component to the reaction vessel is not particularly limited, and examples include a method in which the entire amount is added to the reaction vessel all at once at the beginning; a method in which the entire amount is added to the reaction vessel in portions or continuously; a method in which a portion is added to the reaction vessel initially and the remainder is added to the reaction vessel in portions or continuously. Furthermore, the addition rate of each monomer to the reaction vessel may be changed continuously or stepwise during the reaction, thereby changing the weight ratio of each monomer added per unit time continuously or stepwise, thereby simultaneously synthesizing two or more copolymers with different monomer ratios during the polymerization reaction. The radical polymerization initiator may be charged to the reaction vessel from the beginning, or may be added dropwise to the reaction vessel, or a combination of these may be used depending on the purpose.

[0059] Each polymer obtained as described above can be used as it is for preparing a hydrophilic treatment composition, but if necessary, it may be further neutralized with an alkaline substance before use. Suitable alkaline substances include inorganic salts such as hydroxides and carbonates of monovalent or divalent metals; ammonia; and organic amines. Furthermore, after the reaction is completed, the concentration can be adjusted if necessary.

[0060] The method for producing the hydrophilic treatment composition of the present invention is not particularly limited, but may include, for example, a step of mixing the copolymer (A) with a crosslinking agent, a solvent, hydrophilic particles, and other additives (also referred to as mixing step (A)). The mixing step (A) may be carried out, for example, in the presence of a solvent (preferably an aqueous solvent) or in the absence of a solvent.

[0061] The hydrophilic treatment composition preferably further contains hydrophilic particles (B). The inclusion of the hydrophilic particles (B) can enhance the hydrophilicity retention after wet / dry cycles. The hydrophilic particles (B) may be used singly or in combination of two or more. The hydrophilic particles (B) are preferably hydrophilic particles containing a hydrophilic polymer (b1) having at least one group selected from an acid group, a hydroxyl group, a polyoxyalkylene chain, and a polyvinylpyrrolidone chain, more preferably hydrophilic particles (B1) containing a hydrophilic polymer (b2) having an acid group and / or a hydroxyl group, or hydrophilic particles (B2) containing a hydrophilic polymer (b3) having a polyoxyalkylene chain and a polyvinylpyrrolidone chain, and even more preferably hydrophilic particles (B1) containing a hydrophilic polymer (b2) having an acid group and a hydroxyl group.

[0062] The hydrophilic polymer (b2) having an acid group and / or a hydroxyl group is preferably at least one structural unit selected from a structural unit (B11) derived from a polymerizable monomer having a carboxyl group and a structural unit (B12) derived from a polymerizable monomer having a hydroxyl group, and more preferably a hydrophilic crosslinked polymer (b4) containing, in addition to these, a structural unit (C1) derived from a monomer (C) having two or more polymerizable groups in one molecule (hereinafter referred to as monomer (C)). The structural units (B11) and (B12) of the hydrophilic particle (B1) are the same as the structural units (A11) and (A12) described in the description of the structural unit (A1), and therefore will not be described here.

[0063] The hydrophilic particles (B1) may be structural units (B13) derived from polymerizable monomers having a carboxyl group and a hydroxyl group, and for example, hydroxymethylacrylic acid-based monomers are preferred.

[0064] The content of the structural units (B11) to (B13) in the hydrophilic particles (B1) is, for example, from 5 to 99.9% by mass, and preferably from 40 to 99.9% by mass.

[0065] As described above, the hydrophilic particles (B1) preferably have a structural unit (C1) derived from the monomer (C). It is more preferable that the hydrophilic polymer (b2) contained in the hydrophilic particles (B1) is crosslinked with the monomer (C) (hereinafter referred to as the hydrophilic crosslinked polymer (B1-1)). The monomer (C) is preferably a polyfunctional ethylenically unsaturated monomer having two or more ethylenically unsaturated bond-containing groups, such as a hydrocarbon crosslinkable monomer, a divinyl ether monomer, a diallyl ether monomer, or a polyvalent (meth)acrylic acid ester.

[0066] Examples of hydrocarbon crosslinkable monomers include aromatic hydrocarbon crosslinkable monomers such as divinylbenzene, trivinylbenzene, divinylnaphthalene, divinyltoluene, and divinylxylene; alicyclic hydrocarbon crosslinkable monomers such as trivinylcyclohexane; and chain hydrocarbon crosslinkable monomers such as 1,3-butadiene.

[0067] Preferred divinyl ether monomers include diC1-4 alkylene glycol divinyl ether; polyC1-4 alkylene glycol divinyl ether (the number of repeating alkylene glycol units is not particularly limited, but is preferably 3 to 10); and the like.

[0068] The diallyl ether monomer is preferably diC １－４ Alkylene glycol diallyl ether; PolyC １－４ alkylene glycol diallyl ether (the number of repeating alkylene glycol units is not particularly limited, but is preferably 3 to 10);

[0069] As the polyvalent (meth)acrylic acid ester, polyvalent methacrylic acid esters such as methacrylic acid diesters of mono-, di-, or polyalkylene glycols, methacrylic acid triesters of polyols, methacrylic acid tetraesters of polyols, methacrylic acid pentaesters of polyols, and methacrylic acid hexaesters of polyols are preferred because they have high resistance to hydrolysis, tend to prevent the elution of particle components such as hydrophilic components, and increase the hydrophilicity sustaining effect and / or water slipping property.

[0070] Among the polyfunctional ethylenically unsaturated monomers, hydrocarbon crosslinkable monomers and polyvalent (meth)acrylic acid esters are preferred. In particular, hydrocarbon crosslinkable monomers and polyvalent methacrylic acid esters are more preferred because they have high resistance to hydrolysis and tend to further enhance the hydrophilicity sustaining effect and / or water slippage, aromatic hydrocarbon crosslinkable monomers and methacrylic acid diesters of mono-, di-, or polyalkylene glycols are even more preferred, and divinylbenzene is particularly preferred.

[0071] The hydrophilic particles (B1) may contain one type of structural unit (C1) derived from the monomer (C) alone, or may contain two or more types.

[0072] The content of the structural unit (C1) derived from the monomer (C) in the hydrophilic particles (B1) is preferably from 0.01 to 70% by mass.

[0073] Furthermore, in the hydrophilic particles (B1), the content of the structural unit (C1) derived from the monomer (C) is preferably 0.1 to 45 parts by mass per 100 parts by mass of the structural units (B11 to B13). The combined content of the structural units (B11 to B13) and the structural unit (C1) in the hydrophilic particles (B1) is preferably 50 to 100% by mass, and the upper limit of this combined content may be 99.9% by mass or 99% by mass.

[0074] The polymerizable group contained in the monomer (C) is preferably an ethylenically unsaturated bond-containing group, more preferably a vinyl group or a methacryloyl group, and particularly preferably a vinyl group.

[0075] The monomer (C) preferably has a molecular weight of 50 or more and 1,000 or less, and more preferably 100 or more and 400 or less.

[0076] The hydrophilic particles (B1) may contain one or more structural units (hereinafter, "other structural units (B3)") derived from monomers having a carbon-carbon double bond (hereinafter, "other monomers") other than the structural units (B11 to B13) and the structural unit (C1).

[0077] The other monomers are not particularly limited, and examples thereof include (meth)acrylic monomers, styrene monomers, vinyl ester monomers, silane group-containing monomers, nitrogen atom-containing monomers, oxo group-containing monomers, fluorine atom-containing monomers, epoxy group-containing monomers, light-stabilizing monomers, and ultraviolet absorbing monomers.

[0078] Examples of (meth)acrylic monomers include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate. Among these, (meth)acrylic acid C １－１０ Alkyl esters are preferred, and (meth)acrylic acid C １－５ Alkyl esters are more preferred.

[0079] The styrene-based monomers include those having a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or a tert-butyl group), １－４ styrene, which may have one or more substituents such as alkyl groups, etc. Specific examples of the styrene-based monomer include styrene, α-methylstyrene, p-methylstyrene, tert-butylstyrene, chlorostyrene, and vinyltoluene, with styrene being preferred among them.

[0080] Examples of vinyl ester monomers include esters of saturated fatty acids such as vinyl acetate and vinyl propionate with vinyl alcohol, and among these, C １－５ Preferred are esters of saturated fatty acids of the formula (I) and vinyl alcohol.

[0081] Examples of silane group-containing monomers include alkoxysilyl group-containing silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, and 2-styrylethyltrimethoxysilane; halogenated silyl group-containing silane coupling agents such as vinyltrichlorosilane; and silanol group-containing silane coupling agents such as γ-(meth)acryloyloxypropylhydroxysilane and γ-(meth)acryloyloxypropylmethylhydroxysilane.

[0082] Examples of nitrogen atom-containing monomers include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, dimethylaminoethyl(meth)acrylamide, N-vinylpyrrolidone, and (meth)acrylonitrile.

[0083] Examples of oxo group-containing monomers include ethylene glycol methoxy(meth)acrylate.

[0084] Examples of fluorine atom-containing monomers include (meth)acrylic acid fluoride alkyl esters such as trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, and octafluoropentyl (meth)acrylate. Among these, (meth)acrylic acid C １－１０ Fluorinated alkyl esters are preferred, and (meth)acrylic acid C １－５ Fluorinated alkyl esters are more preferred.

[0085] An example of the epoxy group-containing monomer is glycidyl (meth)acrylate.

[0086] Examples of light stabilizing monomers include 2,2,6,6-tetramethylpiperidine-4-(meth)acrylate.

[0087] Examples of the ultraviolet absorbing monomer include benzotriazole-based ultraviolet absorbing monomers and benzophenone-based ultraviolet absorbing monomers.

[0088] The other monomers are preferably (meth)acrylic monomers, styrene-based monomers, carboxyl group-containing monomers, salts of carboxyl group-containing monomers, and hydroxyl group-containing monomers, more preferably (meth)acrylic acid alkyl esters, (meth)acrylic acid, salts of (meth)acrylic acid, and styrene-based monomers, still more preferably acrylic acid alkyl esters, acrylic acid, and salts of acrylic acid, and particularly preferably acrylic acid and salts of acrylic acid. In particular, the total content of the structural units derived from acrylic acid and the structural units derived from salts of acrylic acid in the hydrophilic particles (B1) may be 0 to 40% by mass.

[0089] The content of the structural unit (B3) derived from other monomers in the hydrophilic particles (B1) is, for example, 40 mass % or less.

[0090] Preferred embodiments of the hydrophilic particles (B1) are described below. The hydrophilic particles (B1) may be composed entirely of the hydrophilic particles (B1) (preferably hydrophilic crosslinked polymer particles (B1-1); the same applies hereinafter), or a portion of the hydrophilic particles (B1) may be composed of another polymer (hereinafter referred to as the second polymer (D)). That is, the hydrophilic particles (B1) may have a single-layer structure or a multilayer structure. Giving the hydrophilic particles (B1) a multilayer structure, preferably a core-shell structure, is also effective in further enhancing hydrophilic properties and water sliding properties. For example, by forming the outermost layer, such as the shell portion, from the hydrophilic polymer (b1) (preferably a hydrophilic crosslinked polymer; the same applies hereinafter) constituting the hydrophilic particles (B1), the particles can be endowed with high hydrophilicity. Alternatively, by reducing the hydrophilicity of the inner layer, such as the core portion, the particles can be endowed with low solubility and low swelling in water, thereby suppressing deterioration and elution of the resulting hydrophilized layer.

[0091] Hereinafter, the case where the hydrophilic particles (B1) have a multilayer structure will be described. For convenience of explanation, the multilayer hydrophilic particles composed of the hydrophilic polymer (b1) and the second polymer (D) constituting the hydrophilic particles (B1) described above will be referred to as "multilayer hydrophilic particles (B1D)." In the multilayer hydrophilic particles (B1D), the second polymer (D) constituting layers other than the outermost layer (for example, the core in the case of core-shell particles) is preferably different from the hydrophilic polymer (b1).

[0092] The second polymer (D) preferably has one or more structural units formed from a non-aqueous monomer that does not have an acidic proton-containing group such as a carboxyl group, a hydroxyl group, a thiol group, or a silanol group, and does not have an amino group. This reduces the hydrophilicity of the inner layer, such as the core portion. The non-aqueous monomer is preferably a monomer formed from a hydrocarbon that may have one or more selected from an ester group, an ether group, an amide group, and a halogeno group, and more preferably a monomer formed from a hydrocarbon that may have an ester group.

[0093] Specific examples of the non-aqueous monomer include (meth)acrylic monomers, styrene-based monomers, vinyl ester-based monomers, oxo group-containing monomers, fluorine atom-containing monomers, epoxy group-containing monomers, etc. Examples of these (meth)acrylic monomers, styrene-based monomers, vinyl ester-based monomers, oxo group-containing monomers, fluorine atom-containing monomers, and epoxy group-containing monomers are the same as the other monomers described above in relation to the other structural unit (A3), and preferred aspects of each monomer are also the same.

[0094] The non-aqueous monomer is preferably a (meth)acrylic monomer or a styrene-based monomer, more preferably a (meth)acrylic acid alkyl ester or a styrene-based monomer, and even more preferably a (meth)acrylic acid C １－５ Alkyl esters, styrene.

[0095] The content of the constitutional units derived from the non-aqueous monomer in the second polymer (D) is 40 to 99 mass %.

[0096] The second polymer (D) preferably further contains one or more structural units derived from a polyfunctional ethylenically unsaturated monomer. This is expected to further enhance the initial hydrophilicity, sustained hydrophilicity, and water slippage of the hydrophilized layer surface. Examples of the polyfunctional ethylenically unsaturated monomer include the same monomers as the polyfunctional ethylenically unsaturated monomers described in the monomer (C). Among them, hydrocarbon crosslinkable monomers and polyvalent (meth)acrylic acid esters are preferred, aromatic hydrocarbon crosslinkable monomers and (meth)acrylic acid diesters of mono-, di-, or polyalkylene glycols are more preferred, and divinylbenzene is even more preferred.

[0097] The content of the structural units derived from the polyfunctional ethylenically unsaturated monomer in the second polymer (D) is preferably 1 to 50% by mass, more preferably 10 to 45% by mass, and even more preferably 20 to 40% by mass. Furthermore, in the second polymer (D), the content of the structural units derived from the polyfunctional ethylenically unsaturated monomer per 100 parts by mass of the structural units derived from the non-aqueous monomer is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, and even more preferably 20 to 50 parts by mass. Furthermore, in the second polymer (D), the total content of the structural units derived from the non-aqueous monomer and the structural units derived from the polyfunctional ethylenically unsaturated monomer is preferably 60 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. The upper limit of the total content may be 99.9% by mass or 99% by mass.

[0098] The second polymer (D) may contain one or more of the structural units (B11 to B13), but preferably does not contain any of them. The content of the structural units (B11 to B13) in the second polymer (D) is preferably less than the content of the structural units (B11 to B13) in the hydrophilic polymer (b1), specifically, it is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0099] The second polymer (D) may contain one or more structural units (D11) derived from a non-aqueous monomer, a structural unit derived from a polyfunctional ethylenically unsaturated monomer, and a monomer having one polymerizable group, such as a carbon-carbon double bond-containing group, per molecule other than the structural units (B11 to B13) (hereinafter, referred to as a "second other monomer").

[0100] Examples of the second other monomer include monomers having a carboxy group, a thiol group, a silanol group, an amino group, etc., such as a carboxy group-containing monomer, a silane group-containing monomer, a hydroxy group-containing monomer, a nitrogen atom-containing monomer, a light-stabilizing monomer, an ultraviolet absorbing monomer, etc. These carboxy group-containing monomers, silane group-containing monomers, hydroxy group-containing monomers, nitrogen atom-containing monomers, light-stabilizing monomers, and ultraviolet absorbing monomers are the same as the other monomers of the other structural unit (B3) described above, and therefore further explanation will be omitted.

[0101] The content of the structural unit (D11) derived from the second other monomer in the second polymer (D) is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less or 3% by mass or less.

[0102] The volume average particle diameter of the hydrophilic particles (B1) (including the multilayered hydrophilic particles (B1D)) is, for example, 10 nm to 10 μm, preferably 10 nm to 5 μm, more preferably 20 nm to 1 μm, and even more preferably 30 nm to 500 nm. The volume average particle diameter can be measured, for example, by dynamic light scattering.

[0103] <Method for producing hydrophilic particles> The method for producing the hydrophilic particles (B1) is not particularly limited, and any conventionally known method may be used, but it is preferable to produce the hydrophilic particles (B1) by polymerizing the monomers constituting the polymer particles (hereinafter, these may be collectively referred to as "raw material monomer components") in an aqueous solvent and, if necessary, partially or completely hydrolyzing them. Examples of the polymerization method include suspension polymerization, emulsion polymerization, dispersion polymerization, etc. Among them, emulsion polymerization, in which the raw material monomer components are dispersed in an aqueous solvent in the presence of an emulsifier and subjected to a (radical) polymerization reaction, is preferred. In emulsion polymerization, for example, a non-aqueous monomer, a polyfunctional ethylenically unsaturated monomer used as needed, a polymerizable monomer that constitutes the structural units (B11 to B13), and a second other monomer are polymerized in an aqueous solvent in a first stage to synthesize seed particles that become the core (i.e., the second polymer (D)), and then monomers that constitute the hydrophilic polymer (b1) (preferably a hydroxymethyl acrylic acid ester, a polyfunctional ethylenically unsaturated monomer, and other monomers used as needed) are polymerized in a second stage to synthesize the shell (i.e., the hydrophilic polymer (B1D)), thereby producing polymer particles (B1D) having a core-shell structure.

[0104] The emulsifier may be used alone or in combination of two or more kinds, and may be a non-reactive surfactant or a reactive surfactant.

[0105] The amount of emulsifier used is preferably 0.05 to 20 parts by mass per 100 parts by mass of the total of the raw material monomer components.

[0106] The aqueous solvent is the same as the aqueous solvent described above for the solvent of the hydrophilic treatment composition, and preferred embodiments thereof are also the same. From the viewpoint of minimizing the amount of water-miscible organic solvent remaining in the hydrophilic particles (B1), an aqueous solvent containing water at 80% by volume or more is preferred, and water alone is most preferred.

[0107] When polymerizing the raw material monomer components, for example, a polymerization initiator, irradiation with ultraviolet rays or radiation, application of heat, or the like is used. The use of a polymerization initiator is preferred, and a polymerization initiator combining an oxidizing agent and a reducing agent (redox polymerization initiator) is preferred. Examples of the oxidizing agent include persulfates such as ammonium persulfate and potassium persulfate, and peroxide-based polymerization initiators such as hydrogen peroxide, benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, and ammonium peroxide. Examples of the reducing agent include soluble sulfites and ascorbic acid.

[0108] If necessary, an appropriate amount of additives such as a chain transfer agent, a pH buffer, a chelating agent, etc. may be added to the reaction system in the emulsion polymerization. The amount of the additive varies depending on the type of additive and cannot be determined in general, but is usually preferably 0.01 to 5 parts by mass per 100 parts by mass of the raw material monomer components.

[0109] The hydrophilic particles (B1) can be hydrolyzed by adding, for example, an aqueous solution of an alkali metal hydroxide such as an aqueous sodium hydroxide solution, an aqueous solution of an amine such as an aqueous cyclohexylamine solution, or an aqueous solution containing a basic substance such as an aqueous ammonia solution. Furthermore, partial or complete neutralization can be carried out by adding an appropriate acid to the solution after hydrolysis. By carrying out hydrolysis and neutralization, the group corresponding to R in the -COOR group contained in the polymer particles can be converted to a hydrogen atom, an alkali metal atom, or ammonium.

[0110] The content of the hydrophilic particles (B1) in the hydrophilic treatment composition of the present invention may be, for example, 0.01% by mass or more, preferably 10% by mass or more, and more preferably 30% by mass or more.

[0111] The hydrophilic particles (B) are preferably hydrophilic particles (B2) having a structural unit derived from at least one group selected from a polyoxyalkylene chain and a polyvinylpyrrolidone chain. The hydrophilic particles (B2) preferably have a structural unit derived from a polyalkylene glycol monomethacrylate such as polyethylene glycol monomethyl ether or methoxypolyethylene glycol monomethacrylate as a group having a polyoxyalkylene chain, or a structural unit derived from a polyvinylidone macromonomer as a group having a polyvinylpyrrolidone chain. Furthermore, the hydrophilic particles (B2) may contain, in addition to (1) a structural unit derived from at least one group selected from a polyoxyalkylene chain and a polyvinylpyrrolidone chain, (2) a structural unit derived from a (meth)acrylamide-based monomer such as (meth)acrylamide or N-methyl(meth)acrylamide, (3) a unit derived from a crosslinkable unsaturated monomer such as N-methylolacrylamide, methylenebisacrylamide, glycidyl methacrylate, γ-methacryloxypropyltrimethoxysilane or N-butoxymethylacrylamide, (4) a structural unit derived from a carboxyl group-containing polymerizable unsaturated monomer such as acrylic acid, methacrylic acid or maleic acid, or (5) a structural unit derived from a monomer having one polymerizable unsaturated group in one molecule, such as an alkyl ester such as methyl(meth)acrylate or a hydroxyalkyl ester of (meth)acrylic acid such as 2-hydroxyethyl(meth)acrylate, and the hydrophilic particles (B2) may also be composed of a copolymer of these (1) to (5), preferably a copolymer of (1) to (4). The monomer may be polymerized by any of various known methods, for example, in a solvent such as propylene glycol monomethyl ether in the presence of a polymerization initiator such as 2,2'-azobis(2-methylbutyronitrile). The volume average particle diameter of the hydrophilic particles (B2) is preferably 10 nm to 10 μm. In the present invention, by incorporating the hydrophilic particles (B2) into a hydrophilic layer containing a hydrophilic treatment composition, the hydrophilic layer can be imparted with good hydrophilicity, as well as a hydrophilicity sustaining effect and / or water slipping property.

[0112] In addition to the hydrophilic particles, silica particles may also be used, such as silica sol and finely powdered silica.

[0113] The hydrophilic treatment composition of the present invention may contain other additives within the range that does not impair the effects of the present invention. Examples of the other additives that can be used include additives that are commonly used in this technical field, such as water-soluble low-molecular-weight compounds having a hydroxyl group, such as L-ascorbic acid, gallic acid, and tannic acid, and polymeric compounds having a hydroxyl group, such as polyvinyl alcohol.

[0114] A preferred embodiment of the hydrophilic treatment composition of the present invention will be described. [Hydrophilic layer formed using the hydrophilic treatment composition] The hydrophilic layer, such as a hydrophilic coating film, formed from the hydrophilic treatment composition of the present invention contains the above-mentioned hydrophilic treatment composition, and therefore has not only good hydrophilicity but also sustained hydrophilicity and / or good water-slip properties. Therefore, the hydrophilic treatment composition is suitably applied to tangible objects (i.e., objects to be hydrophilized) that require not only hydrophilicity but also sustained hydrophilicity and / or water-slip properties, and is particularly suitably used for hydrophilic coating films applied to fin materials (heat exchanger fins) of heat exchangers.

[0115] As a specific example of a configuration in which the hydrophilic treatment composition of the present invention is applied, a heat exchanger fin having a hydrophilic layer (e.g., a hydrophilic coating film) containing the copolymer (A) formed on its surface is one preferred embodiment. The thickness of the hydrophilic layer formed on the fin is preferably, for example, 0.1 to 80 μm.

[0116] In addition, when the hydrophilic layer exhibits a hydrophilicity sustaining effect, it is preferable that the following (a) and (b) are satisfied, for example: (a) the initial contact angle (θ0) measured by the method described in <Evaluation of initial hydrophilicity> in the Examples is less than 40°; (b) the contact angle (θ5) after wet / dry cycling measured by the method described in <Evaluation of hydrophilicity sustaining effect after wet / dry cycling> in the Examples is less than 40°.

[0117] The initial contact angle of the hydrophilized layer is preferably less than 35°, more preferably 30° or less, even more preferably 20° or less, and particularly preferably 15° or less or less than 15°. The lower limit of the initial contact angle is not particularly limited, but is, for example, 5° or more.

[0118] The contact angle (θ5) of the hydrophilized layer is preferably less than 35°, more preferably 30° or less, even more preferably 26° or less, still more preferably 20° or less, and particularly preferably 15° or less or less than 15°. The lower limit of the contact angle is not particularly limited, but is, for example, 8° or more.

[0119] In a more preferred embodiment, the relationship between the initial contact angle (θ0) and the contact angle (θ5) in the hydrophilized layer satisfies the following (c) or (d): (c) contact angle (θ5)≦initial contact angle (θ0); (d) contact angle (θ5)>initial contact angle (θ0), and the absolute value of the difference between the contact angle (θ5) and the initial contact angle (θ0) is 20° or less. When the relationship between the initial contact angle (θ0) and the contact angle (θ5) in the hydrophilized layer satisfies (c), any absolute value of the difference between the contact angle (θ5) and the initial contact angle (θ0) is preferred, but 1° or more is more preferred, and 3° or more is even more preferred. The upper limit of the absolute value of the difference is not particularly limited, but is, for example, 15° or less. When the relationship between the initial contact angle (θ0) and the contact angle (θ5) in the hydrophilic layer satisfies the condition (d), the smaller the absolute value of the difference between the contact angle (θ5) and the initial contact angle (θ0) is, the better. Specifically, the absolute value is 20° or less, preferably 15° or less, and more preferably 10° or less.

[0120] When the hydrophilized layer exhibits both hydrophilicity and water-slippage properties, it is preferable that the hydrophilized layer satisfy the above-mentioned initial contact angle (θ0) and the following condition (i): (i) the sliding angle (θs) measured by the method described in <Evaluation of water-slippage properties> in the examples is less than 30°

[0121] The sliding angle (θs) of the hydrophilized layer is preferably 20° or less, more preferably 15° or less or less than 15°, even more preferably 12° or less, and particularly preferably 10° or less. Conventional sliding angle measurements did not take into account the influence of wetting and spreading of a droplet due to the hydrophilicity of the measurement substrate surface. Therefore, for a hydrophilic tangible object (i.e., a hydrophilized layer), a good sliding angle measured by a conventional measurement method did not necessarily mean good water-slip properties. That is, in conventional methods, the sliding angle was determined by the inclination angle of the hydrophilized layer when a water droplet was placed on the hydrophilized layer and the water droplet moved a certain distance in the sliding direction. However, when a water droplet was placed on the hydrophilized layer, the wetting and spreading movement of the water droplet was observed. When the sliding angle was measured under this condition, both sliding and wetting movements were observed simultaneously, which sometimes made it difficult to accurately evaluate the water-slip properties. It was also possible to measure the sliding angle after the wetting and spreading movement reached an equilibrium point, but this is not preferable because the water in the droplet may evaporate before reaching the equilibrium point. Therefore, in order for a hydrophilized layer having hydrophilic properties to have good water-sliding properties, it is required that the sliding angle be small in a measurement system that takes into account the influence of the wetting and spreading of a water droplet.On the other hand, in the evaluation of water-sliding properties of the present invention, as will be described later, an evaluation method is adopted that aims to extract the end point movement due to sliding from the end point movement of a water droplet in the sliding direction, excluding the influence of the end point movement due to wetting and spreading.In this evaluation method, the hydrophilized layer of the present invention that can reduce the sliding angle can be said to have good water-sliding properties while being hydrophilic.

[0122] The shape of the hydrophilic layer is not particularly limited, and examples thereof include a coating film shape, a surface shape (film, sheet, plate), granular, powdery, lumpy, particle aggregate shape, spherical, oval sphere shape, lens shape, columnar, rod shape, conical shape, cylinder shape, needle shape, fiber shape, fiber aggregate shape (e.g., woven fabric, nonwoven fabric, etc.), hollow fiber shape, porous shape, etc. Among these, a coating film shape is preferred.

[0123] The thickness of the hydrophilic layer is not particularly limited, but is, for example, 0.1 to 80 μm, preferably 0.1 to 50 μm, more preferably 0.1 to 10 μm, and even more preferably 0.3 to 5 μm.

[0124] The method for producing the hydrophilic layer is not particularly limited, and any conventionally known method may be appropriately adopted. For example, the hydrophilic layer can be obtained by molding or forming the hydrophilic treatment composition described above.

[0125] Furthermore, according to the present invention, by providing a hydrophilic layer containing the hydrophilic treatment composition of the present invention on the surface of a substrate, which is the object of hydrophilic treatment, it is possible to impart sustained hydrophilicity and / or water slippage to the surface of the substrate. That is, according to the present invention, by providing a hydrophilic layer containing the hydrophilic treatment composition on the surface of a substrate, it is possible to provide sustained hydrophilicity and / or water slippage to the surface of the substrate. In both cases of forming a hydrophilic layer containing a hydrophilic treatment composition and forming a hydrophilic layer containing a hydrophilic treatment composition on the surface of a substrate, the forming or forming method is not particularly limited, and may be appropriately selected depending on the type of composition used and the shape of the target substrate. Examples of forming or forming methods include a method of forming a film by applying the hydrophilic treatment composition to a substrate by coating, spraying, printing, impregnation, etc.; a method of forming a molded body by injection molding, extrusion molding, vacuum molding, compression molding, blow molding, etc. of the hydrophilic treatment composition; and a method of laminating the hydrophilic treatment composition on the surface of a substrate. Among these, it is preferable to form a hydrophilic layer containing the hydrophilic treatment composition on the surface of the substrate by applying the hydrophilic treatment composition to the substrate.

[0126] The hydrophilic treatment object, such as a substrate, may be made of a resin, such as polyester, polyethylene, polypropylene, triacetyl cellulose, polystyrene, polycarbonate, polyethersulfone, cellophane, polyamide, polyvinyl alcohol, polyacetal, polyphenylene ether, polyphenylene sulfide, polyimide, polyamideimide, polyetherimide, polyetheretherketone, fluororesin such as polytetrafluoroethylene, ABS resin, Noryl resin, acrylic resin, epoxy resin, cellophane, etc. In addition to the resins, inorganic materials such as glass, slate, and mortar; metals such as stainless steel plate, iron, copper, aluminum, magnesium, and zinc, and their alloys; etc., are also included, but the present invention is not limited to these examples. The hydrophilic treatment object may be made of only a single layer, or may have a laminate structure in which multiple layers are stacked. In particular, the hydrophilic treatment object is preferably a fin material for a heat exchanger, and more preferably an aluminum fin material.

[0127] When a hydrophilic treatment composition is applied to an object to be hydrophilized by coating, spraying, printing, impregnation, or other methods to form a coating film (hereinafter referred to as a hydrophilic coating film), if a crosslinking agent is applied to the hydrophilic coating film, it may be mixed in advance with the hydrophilic treatment composition or may be added after film formation. When a hydrophilic layer containing the hydrophilic treatment composition of the present invention is applied to a fin material (particularly an aluminum fin material) of a heat exchanger, it may be formed directly on the surface of the fin material (particularly an aluminum plate constituting the aluminum fin material) (i.e., the fin material (particularly an aluminum plate constituting the aluminum fin material) and the hydrophilic layer may be directly laminated), or it may be formed via an underlayer such as a chemical conversion layer and / or a resin coating layer provided on the surface of the fin material (particularly an aluminum plate constituting the aluminum fin material) for the purpose of preventing corrosion of the fin material (particularly the aluminum constituting the aluminum fin material) (i.e., the fin material (particularly the aluminum plate constituting the aluminum fin material) and the hydrophilic layer may be laminated via an underlayer).

[0128] The chemical conversion treatment layer can be a conventionally known one, for example, a layer made of an inorganic oxide or an inorganic-organic composite compound. The inorganic material constituting the inorganic oxide or inorganic-organic composite compound preferably has a main component of chromium, zirconium, or titanium. A layer made of an inorganic oxide can be formed, for example, by subjecting a fin material (particularly an aluminum plate constituting an aluminum fin material) to a chromate phosphate treatment, a zirconium phosphate treatment, a zirconium oxide treatment, a chromate chromate treatment, a zinc phosphate treatment, a titanic acid phosphate treatment, or the like. A layer made of an inorganic-organic composite compound can be formed, for example, by subjecting a fin material (particularly an aluminum plate constituting an aluminum fin material) to a coating-type chromate treatment, a coating-type zirconium treatment, or the like. Specific examples of such inorganic-organic composite compounds include, for example, an acrylic-zirconium composite.

[0129] The resin coating layer can be formed, for example, by applying a resin-containing resin paint to the fin material (particularly the aluminum plate or chemical conversion coating layer that constitutes the aluminum fin material) and solidifying it by drying or the like. The resin can be a conventionally known resin, such as polyester-based, polyolefin-based, epoxy-based, urethane-based, or (meth)acrylic resin, and a mixture of one or more of these can be used. Among these, (meth)acrylic resins are preferred, and a polymer having a (meth)acrylic resin or the like as a main chain and containing an oxazoline group in the side chain can also be used.

[0130] In addition to the above, the resin coating layer may contain other optional components within the range that does not impair the effects of the present invention. These optional components include various paint additives for improving coatability, workability, and film physical properties, such as aqueous solvents, crosslinking agents, surfactants, film-forming aids, surface conditioners, wetting and dispersing agents, anti-settling agents, antioxidants, antifoaming agents, rust inhibitors, antibacterial agents, and anti-fungal agents. These paint additives may be used alone or in combination of two or more.

[0131] The method for producing the hydrophilic layer is not particularly limited, but may include a drying step or a curing step after the film-forming step such as coating, spraying, printing, or impregnation.

[0132] This application claims the benefit of priority based on Japanese Patent Application No. 2024-070007, filed on April 23, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-070007, filed on April 23, 2024, are incorporated herein by reference.

[0133] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples, and can of course be practiced with appropriate modifications within the scope of the above and below-described aims, all of which are included within the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

[0134] <Gel Permeation Chromatography (GPC)> The weight-average molecular weight of the copolymers produced in the following Production Examples was measured by the following method. Apparatus: Alliance (e2695) (manufactured by Waters) Analysis software: Empower2 Professional + GPC option (manufactured by Waters) Columns used: TSKguard columns SWXL (inner diameter: 6.0 mm × 40 mm) + TSKgel G4000SWXL (inner diameter: 7.8 mm × 300 mm) + G3000SWXL (inner diameter: 7.8 mm × 300 mm) + G2000SWXL (inner diameter: 7.8 mm × 300 mm) (all manufactured by Tosoh Corporation) Detector: differential refractometer (RI) detector (manufactured by Waters, Waters 2414) Eluent: 115.6 g of sodium acetate trihydrate dissolved in a mixed solvent of 10,999 g of ion-exchanged water and 6,001 g of acetonitrile, and further adjusted to pH 6.0 with acetic acid. Flow rate: 1 mL / min. Column temperature: 40°C. Measurement time: 45 min. Sample injection amount: 100 μL (eluent solution with a sample concentration of 0.5% by mass). GPC standard sample: polyethylene glycol manufactured by Tosoh Corporation, Mp = 255,000, 200,000, 107,000, 72,750, 44,900, 31,400, 21,300, 11,840, 6,450, 4,020, 1,470. Calibration curve: Created using a cubic equation using the Mp values ​​of the above polyethylene glycol.

[0135] <High-Performance Liquid Chromatography (LC)> The remaining amounts of various monomers used as reaction raw materials in the following production examples were measured under the following conditions and used to calculate the composition of the copolymer. Apparatus: Alliance 2695 (Waters) Analysis software: Empower Professional (Waters) Column: Atlantis dC18 5 μm (inner diameter 4.6 mm × length 250 mm) × 2 (Waters) Detector: differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996) Solvent: solution of 100 mM aqueous sodium acetate solution and acetonitrile mixed in a 6:4 ratio Flow rate: 1 mL / min Column temperature: 40°C Measurement time: 30 min Sample solution injection amount: 100 μL (sample concentration: 1% by mass)

[0136] <Evaluation of Initial Hydrophilicity> Using an automatic contact angle meter ("CA-X" manufactured by Kyowa Interface Science Co., Ltd.), a 2 μL droplet of pure water was prepared at 25° C. and applied to the surface of the coating film (hydrophilized layer) of the film-formed sample prepared as described below, and the contact angle was calculated by the θ / 2 method. The contact angle value 30 seconds after application was taken as the measured value, and five measurements were performed, and the average value of three points excluding the maximum and minimum values ​​was taken as the initial contact angle of the coating film (hydrophilized layer). The initial hydrophilicity of the coating film (hydrophilized layer) was quantitatively evaluated according to the following criteria: ◎: Initial contact angle less than 15° ○: Initial contact angle 15° or more but less than 40° ×: Initial contact angle 40° or more

[0137] <Evaluation of Hydrophilicity Sustaining Effect After Wet / Dry Cycles> The coating film (hydrophilized layer) of the film-formed sample prepared as described below was immersed in pure water for 6 hours, and then, in an environment of 25°C and 50% humidity, the removed film-formed sample was placed on a Kimwipe so that the contact angle measurement surface (coated surface of the sample) was facing up, and another Kimwipe was covered from above and maintained in this state for 5 seconds. The sample was then removed, and excess water was removed by blowing air onto the contact angle measurement surface until no visible water droplets remained. The sample was then dried at 80°C in an air atmosphere using an air-blowing constant temperature incubator (Yamato Scientific Co., Ltd., "DNF400") for 2 hours to obtain a sample after wet / dry cycling. Using an automatic contact angle meter (Kyowa Interface Science Co., Ltd., "CA-X"), a 2 μL droplet of pure water was prepared at 25°C and applied to the coating surface of the sample after wet / dry cycling, and the contact angle was calculated using the θ / 2 method. The contact angle value 30 seconds after contact with the surface was taken as the measured value, and five measurements were taken. The average of the three measurements, excluding the maximum and minimum values, was taken as the contact angle after the wet / dry cycle. The hydrophilicity retention effect of the coating film after the wet / dry cycle was quantitatively evaluated according to the following criteria: ◎: Contact angle after the wet / dry cycle is less than 15° ○: Contact angle after the wet / dry cycle is 15° or more but less than 40° ×: Contact angle after the wet / dry cycle is 40° or more

[0138] <Evaluation of Water Slippage> To evaluate the sliding properties, the sliding angle of a water droplet relative to the coating surface of the film-formed sample was measured. The water slippage was evaluated using a sample after five wet / dry cycles. Specifically, using an automatic contact angle meter ("CA-X" manufactured by Kyowa Interface Science Co., Ltd.), a 10 μL droplet of pure water was prepared at 25°C and deposited on the horizontally placed coating surface after the heat cycle (5C) (the coating surface of the sample after the heat cycle). 0.1 seconds after deposition, the sample was gradually tilted at a rate of 2° / sec in 0.5° increments, and the angle at which the water droplet began to move was recorded as the measured value. Five measurements were taken, and the average of the three points, excluding the maximum and minimum values, was taken as the sliding angle θs. The water slippage of the coating was then quantitatively evaluated according to the following criteria. ◎: sliding angle θs less than 15° ○: sliding angle θs 15° or more and less than 30° ×: sliding angle θs 30° or more Note that, as shown in Figure 1, the movement of the water droplet was determined as follows: R0 was the end point of the water droplet (2a) on the opposite side to the sliding direction 0.1 seconds after it landed on the coating surface of the formed sample 1, and L0 was the end point on the sliding direction side; Rθ was the end point of the water droplet (2b) on the opposite side to the sliding direction at an inclination angle θ, and Lθ was the end point on the sliding direction side; the movement distance of the end point on the opposite side to the sliding direction of the water droplet dR = -|Rθ - R0|, and the movement distance of the end point on the sliding direction side of the water droplet dL = |Lθ - L0|. The water droplet was determined to have moved when dR + dL > 1.00 mm was first satisfied, and the inclination angle θ at that time was defined as the sliding angle θs. This definition is an evaluation method intended to extract the end point movement due to sliding by excluding the influence of the end point movement due to wetting and spreading from the end point movement of the water droplet in the sliding direction.

[0139] [Copolymer (A)] Production Example 1: Ion-exchanged water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser. The atmosphere in the reaction vessel was then replaced with nitrogen under stirring. The temperature was raised to 60°C under a nitrogen atmosphere, and then an aqueous hydrogen peroxide solution was added. Next, an aqueous solution of acrylic acid (AA), an unsaturated polyalkylene glycol monomer (IPN-10) in which an average of 10 moles of ethylene oxide had been added to 3-methyl-3-buten-1-ol, and 3-mercaptopropionic acid dissolved in ion-exchanged water was added dropwise over a period of 4 hours, and an aqueous solution of L-ascorbic acid dissolved in ion-exchanged water was added dropwise over a period of 4.5 hours, each at a constant rate. The temperature during this period was kept constant at 60°C, and after completion of the dropwise addition, the temperature was maintained at 60°C for 1 hour to terminate the polymerization reaction. The pH of the reaction solution was then neutralized to pH 6 using an aqueous sodium hydroxide solution at a temperature below the polymerization reaction temperature, yielding an aqueous solution containing copolymer (1).

[0140] Production Examples 2 to 6, 11, and 12 Copolymers (2) to (6), (11), and (12) were produced in the same manner as Production Example 1, except that the proportions of the structural units were changed as shown in Table 1, and in Production Examples 11 and 12, the structural unit (A2) was further changed.

[0141] Production Examples 7, 8, and 13 Copolymers (7), (8), and (13) were produced in the same manner as Production Example 1, except that acrylic acid (AA) was replaced with 2-hydroxyethyl acrylate (HEA), the proportions of the various structural units were changed, and in Production Example 13, the structural unit (A2) was changed, as shown in Table 1.

[0142] Production Examples 9, 10, and 14 Copolymers (9), (10), and (14) were produced in the same manner as Production Example 1, except that acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA) were used in combination and the proportions of the respective structural units were changed as shown in Table 1, and furthermore, in Production Example 14, the structural unit (A2) was changed.

[0143] Production Examples 15 and 16 Copolymers (15) and (16) were produced in the same manner as in Example 1, except that the structural unit (A2) was not used.

[0144] Production Example 17 (Hydrophilic Particles (1)) Into a stainless steel first reaction kettle equipped with a stirrer, a thermometer, and a cooler, 1,128 parts by mass of deionized water and 1.05 parts by mass of ADEKA REASOAP SR-20 (active ingredient 100% by mass, manufactured by ADEKA Corporation) diluted with ion-exchanged water to 10% by mass of the active ingredient (hereinafter referred to as "SR-20 (active ingredient 10% by mass)") were added, and the internal temperature was raised to 75°C and maintained at that temperature. Meanwhile, in a second reaction kettle different from the first reaction kettle, 70 parts by mass of methyl methacrylate (MMA) and 30 parts by mass of divinylbenzene (DVB810, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) were mixed to prepare 100 parts by mass of Monomer Composition A. Furthermore, in a third reactor different from the first and second reactors, 80 parts by mass of methyl 2-hydroxymethylacrylate (RHMA), 10 parts by mass of divinylbenzene (DVB810 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and 10 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME400 manufactured by NOF Corporation) were mixed to prepare 100 parts by mass of monomer composition B. Next, the atmosphere inside the first reactor was purged with nitrogen gas, and then 100 parts by mass of the monomer composition A, 20 parts by mass of hydrogen peroxide solution (concentration 3.35% by mass), and 20 parts by mass of an aqueous L-ascorbic acid solution (concentration 5.0% by mass) were added to the first reactor, the internal temperature was maintained at 75 ° C., and an initial polymerization reaction was carried out over 2 hours. Subsequently, 100 parts by mass of the monomer composition B, 100 parts by mass of hydrogen peroxide solution (concentration 0.83% by mass), 100 parts by mass of an L-ascorbic acid aqueous solution (concentration 1.25% by mass), and 100 parts by mass of a mixed composition of 7.04 parts by mass of SR-20 (active ingredient 10% by mass), 0.36 parts by mass of an aqueous ammonia solution (concentration 28% by mass), and 92.6 parts by mass of ion-exchanged water were each added dropwise uniformly to the first reaction kettle from different inlets over a period of 3 hours. After completion of the addition, the internal temperature of the first reaction kettle was maintained at 75°C, and the mixture was aged at the same temperature for 2 hours. The reaction solution was then cooled to obtain an aqueous dispersion of polymer particles (a1). 10 parts by mass of the aqueous dispersion of polymer particles (a1) obtained above and 1.2 parts by mass of an aqueous sodium hydroxide solution (concentration 20%) as a basic aqueous solution were added to the first reaction kettle and stirred overnight at 25°C to obtain an aqueous dispersion of hydrolyzed hydrophilic particles (1) as shown in Table 2. The volume average particle diameter of the obtained hydrophilic particles (1) was 302 nm.

[0145] [Hydrophiliic Treatment Composition] Hydrophilic Treatment Composition 1 Hydrophilic treatment composition 1 was produced using the copolymer (1) produced in Production Example 1. The copolymer (1) and an aqueous crosslinking agent ("Epocross WS-700" manufactured by Nippon Shokubai Co., Ltd.; solid content 25% by mass) were blended in a solid content ratio (mass basis) of 100:18, and the mixture was diluted with pure water to a final solid content of 5.5% by mass, thereby obtaining hydrophilic treatment composition 1.

[0146] Hydrophilic Treatment Compositions 2 to 14, 18, and 19 Hydrophilic treatment compositions 2 to 14, 18, and 19 were produced in the same manner as in Example 1, except that copolymer (1) was changed as shown in Table 3.

[0147] Hydrophilic treatment composition 15 Hydrophilic treatment composition 15 was produced using copolymer (5) and hydrophilic particles (1). Copolymer (5), which is a hydrophilic resin, hydrophilic particles (1), and an aqueous crosslinking agent ("Epocross WS-700" manufactured by Nippon Shokubai Co., Ltd.; solid content 25% by mass) were blended in a solid content ratio (mass basis) of 100:100:18, and the mixture was diluted with pure water to a final solid content of 5.5% by mass, thereby obtaining hydrophilic treatment composition 15.

[0148] Hydrophilic Treatment Compositions 16 and 17 Hydrophilic treatment compositions 16 and 17 were produced in the same manner as in Example 15, except that the copolymer was changed as shown in Table 1.

[0149] [Film-formed sample] Film-formed sample 1 Film-formed sample 1 was prepared using hydrophilic treatment composition 1. Specifically, the hydrophilic treatment composition (1) was applied to the undercoat layer-coated surface of an aluminum plate using a bar coater so that the film thickness after coating would be 1.0 μm, and the applied film was dried at 200° C. for 60 seconds in an automatic discharge dryer ("AT-101 (standard type)" manufactured by Tojo Netsugaku Co., Ltd.), to obtain film-formed sample 1 having a laminated coating film.

[0150] Film-formed Samples 2 to 19 Film-formed Samples 2 to 19 were prepared in the same manner as Film-formed Sample 1, except that the hydrophilic treatment composition was changed.

[0151] In the table, AA: acrylic acid HEA: 2-hydroxyethyl acrylate IPN-10: ethylene oxide adduct of 3-methyl-3-buten-1-ol (average number of moles added: 10 moles) IPN-50: ethylene oxide adduct of 3-methyl-3-buten-1-ol (average number of moles added: 50 moles) MLA-200: ethylene oxide adduct of methallyl alcohol (average number of moles added: 200 moles) The amount of basic aqueous solution added represents the number of moles of added base when the number of moles of RHMA in the polymer particles (hydrophilic particles) is taken as 100 mol %, and corresponds to the ionization rate and hydrolysis rate.

[0152]

[0153]

[0154]

[0155] The results in Table 4 show that the use of the hydrophilic treatment composition of the present invention can impart good hydrophilicity and good water-sliding properties to a coating film, and can also improve the durability of the hydrophilicity of the resulting coating film after wet / dry cycles.

[0156] 1. Film-formed sample 2a. Water droplet 0.1 seconds after landing 2b. Water droplet at tilt angle θ R0. End point on the opposite side of the sliding direction of the water droplet 0.1 seconds after landing L0. End point on the sliding direction side of the water droplet 0.1 seconds after landing Rθ. End point on the opposite side of the sliding direction of the water droplet at tilt angle θ Lθ. End point on the sliding direction side of the water droplet at tilt angle θ

Claims

1. A hydrophilization treatment composition characterized by containing a copolymer (A) having at least one structural unit (A1) selected from the structural unit (A11) derived from a polymerizable monomer having a carboxyl group and the structural unit (A12) derived from a polymerizable monomer having a hydroxyl group, and a structural unit (A2) derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond.

2. The hydrophilic treatment composition according to claim 1, wherein the hydrocarbon group contained in the structural unit (A2) is an aliphatic hydrocarbon group.

3. The hydrophilic treatment composition according to claim 1, wherein the structural unit (A2) is derived from a monomer represented by the following formula: (In the formula, R １ , R ２ R each independently represents a hydrogen atom or a methyl group. ３ represents an alkylene group having 1 to 4 carbon atoms. ４ represents an alkylene group having 2 to 4 carbon atoms, a is 0 or 1, and b represents the average number of moles added of 2 to 500.

4. The hydrophilic treatment composition according to claim 1, further comprising hydrophilic particles (B) having at least one group selected from the group consisting of an acid group, a hydroxyl group, a polyoxyalkylene chain, and a polyvinylpyrrolidone chain.

5. The hydrophilic treatment composition according to claim 1, further comprising a crosslinking agent.

6. The hydrophilic treatment composition according to claim 5, wherein the crosslinking agent has two or more oxazoline groups in one molecule.

7. The hydrophilic treatment composition according to claim 4, wherein the volume average particle size of the hydrophilic particles is 10 nm to 10 μm.

8. The hydrophilic treatment composition according to claim 1 or 5, wherein the object to be hydrophilically treated is a fin of a heat exchanger.

9. The hydrophilic treatment composition according to claim 1, wherein the structural unit (A11) derived from a polymerizable monomer having a carboxyl group is a structural unit derived from an unsaturated monocarboxylic acid or a salt thereof.

10. The hydrophilic treatment composition according to claim 9, wherein the unsaturated monocarboxylic acid or its salt is acrylic acid, methacrylic acid, or its salt.

11. The hydrophilic treatment composition according to claim 1, wherein the structural unit (A12) derived from a polymerizable monomer having a hydroxyl group is a structural unit derived from a (meth)acrylic acid hydroxyalkyl ester.

12. The hydrophilization treatment composition according to claim 1, wherein the structural unit (A2) is a structural unit derived from an ethylene oxide adduct of 2-methyl-2-propen-1-ol or an ethylene oxide adduct of 3-methyl-3-buten-1-ol.

13. The hydrophilic treatment composition according to claim 1, wherein the content of the structural unit (A2) is 30 to 99 parts by mass per 100 parts by mass of the total of the structural unit (A1) and the structural unit (A2).

14. The hydrophilic treatment composition according to claim 1, wherein the total content of the structural unit (A1) and the structural unit (A2) is 70 to 100 parts by mass per 100 parts by mass of the copolymer (A).

15. The hydrophilic treatment composition according to claim 4, wherein the hydrophilic particles (B) are hydrophilic particles (B1) containing a hydrophilic polymer (b2) having an acid group and a hydroxyl group.

16. A heat exchanger fin having a hydrophilic layer formed on its surface, the hydrophilic layer comprising a copolymer (A) having at least one structural unit (A1) selected from a structural unit (A11) derived from a polymerizable monomer having a carboxyl group and a structural unit (A12) derived from a polymerizable monomer having a hydroxyl group, and a structural unit (A2) derived from a monomer in which a polyoxyalkylene group and a hydrocarbon group having a polymerizable double bond are linked via an ether bond.

17. The fin according to claim 16, wherein the thickness of the hydrophilic layer is 0.1 to 80 μm.

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