Hydrophilic copolymer and hydrophilic composition

Abstract

To provide a hydrophilic copolymer that yields a coating film having excellent hydrophilicity and antifogging properties.SOLUTION: Provided is a hydrophilic copolymer containing a structural unit (a) represented by formula (1) and a structural unit (b) represented by formula (2). (In formula (1), R1 represents H or a methyl group, R2 represents -(C2H4O)m-R6 or -(C3H6O)m-R6, m represents an integer of 1-50, R6 represents H or a C1-6 alkyl group, and X1 represents a divalent linking group, and in formula (2), R3 represents H or a methyl group, R4 and R5 each independently represent a C1-10 alkyl group or a C6-10 aryl group, X2 represents a divalent linking group, n represents an integer of 1-3, and an asterisk * represents a bond to an adjacent structural unit).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydrophilic copolymer and a hydrophilic composition containing the hydrophilic copolymer. [Background technology]

[0002] In recent years, there has been an increasing demand for improvements in the fogging of substrates made of organic materials such as plastics and inorganic materials such as glass. Improvement of the fogging of a substrate is generally achieved by coating the surface of the substrate with a hydrophilic film. For example, Patent Document 1 proposes a coating composition containing a hydrophilic copolymer having a highly hydrophilic quaternary ammonium salt structure as a coating agent capable of imparting hydrophilicity to a substrate.

[0003] However, the coating film formed by the above coating composition does not have sufficient water resistance, and after contact with water, the hydrophilic composition in the coating film is partially eluted, resulting in deterioration of surface properties such as hydrophilicity and anti-fogging properties. When such areas dry, water drip marks may remain on the coating film. Furthermore, the heat resistance was insufficient, and the anti-fogging properties of the coating film were sometimes lost after being left standing in an environment of 120°C for 24 hours. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-162431 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydrophilic copolymer that gives a coating film excellent in hydrophilicity and antifogging properties, and a hydrophilic composition containing the same. [Means for solving the problem]

[0006] As a result of extensive research to achieve the above object, the present inventors have found that a specific hydrophilic copolymer provides a coating film that has excellent water resistance and can impart long-lasting, heat-resistant hydrophilicity and anti-fogging properties to substrates formed from organic materials such as plastics and inorganic materials such as glass, and have thereby completed the present invention.

[0007] That is, the present invention provides: 1. A hydrophilic copolymer comprising a structural unit (a) represented by the following formula (1) and a structural unit (b) represented by the following formula (2): [ka] (In formula (1), R 1 represents a hydrogen atom or a methyl group, and R 2 is -(C2H4O) m -R 6 or -(C3H6O) m -R 6 m represents an integer of 1 to 50; R 6 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and X 1 represents a divalent linking group, In formula (2), R 3 represents a hydrogen atom or a methyl group, and R 4 and R 5 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; X 2 represents a divalent linking group, n represents an integer of 1 to 3, and an asterisk * indicates a bond to an adjacent structural unit. 2. The above X 1 and X 2 are each independently a divalent linking group having one or more bonds selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond; 3. A hydrophilic composition comprising one or two hydrophilic copolymers; 4. Coating obtained by curing the hydrophilic composition of 3 to provide. [Effects of the Invention]

[0008] The hydrophilic copolymer of the present invention provides a hydrophilic composition capable of forming a coating film that has excellent water resistance and can impart long-lasting, heat-resistant hydrophilicity and anti-fogging properties to organic substrates such as plastics and inorganic substrates such as glass. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be specifically described below. [1] Hydrophilic copolymer The hydrophilic copolymer according to the present invention (hereinafter also simply referred to as "copolymer") contains the structural unit (a) and the structural unit (b) described below. Each constituent unit of the hydrophilic copolymer according to the present invention will be described below. The structural unit (a) contained in the hydrophilic copolymer of the present invention is represented by the following formula (1).

[0010] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0011] In formula (1), R 1 is a hydrogen atom or a methyl group, preferably a hydrogen atom. R 2 is -(C2H4O) m -R 6 or -(C3H6O) m -R 6 m is an integer of 1 to 50, preferably an integer of 2 to 10, and more preferably an integer of 2 to 5. R 6 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. This alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and cyclohexyl groups. Among these, R 6From the viewpoint of improving the hydrophilicity of the coating film, is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. R 2 Specific examples of the compound include, but are not limited to, those represented by the following formulas:

[0012] [ka]

[0013] X 1 represents a divalent linking group. There are no particular limitations on this divalent linking group, but a divalent linking group having one or more bonds selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond is preferred, and —(CH) k1 -Z-(CH2) k2 A linking group represented by - (Z represents a urethane bond, a urea bond, a thiourethane bond or a thiourea bond, and k1 and k2 each independently represent an integer of 1 to 5, preferably 2 to 4) is more preferred. X 1 Specific examples of the divalent linking group include, but are not limited to, those represented by the following formulae:

[0014] [ka]

[0015] Specific examples of the structural unit (a) represented by the above formula (1) include, but are not limited to, those represented by the following formulas.

[0016] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0017] The structural unit (b) contained in the hydrophilic copolymer of the present invention is represented by the following formula (2). The hydrolyzable silyl group contained in the structural unit (b) can undergo a crosslinking reaction with itself (self-crosslinking), thereby forming a crosslinked structure containing a hydrophilic copolymer in the coating film.

[0018] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0019] In formula (2), R 3 is a hydrogen atom or a methyl group, preferably a methyl group. R 4 and R 5 are each independently an alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms. R 4 and R 5 The alkyl group may be linear, branched, or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, and cyclohexyl groups. R 4 and R 5 Specific examples of the aryl group include phenyl and tolyl groups. Among these, R 4 is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group, and R 5 is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. n represents an integer of 1 to 3, with 3 being preferred.

[0020] X 2 represents a divalent linking group. There are no particular limitations on this divalent linking group, but a divalent linking group having one or more bonds selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond is preferred, and —(CH) k1 -Z-(CH2) k2A linking group represented by - (Z represents a urethane bond, a urea bond, a thiourethane bond or a thiourea bond, and k1 and k2 each independently represent an integer of 1 to 5, preferably 2 to 4) is more preferred. X 2 Specific examples of the divalent linking group include, but are not limited to, those represented by the following formula: Among these, those containing a urea bond represented by formula (3) are preferred.

[0021] [ka]

[0022] Specific examples of the structural unit (b) represented by the above formula (2) include, but are not limited to, those represented by the following formulas.

[0023] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0024] In the hydrophilic copolymer of the present invention, the content of the structural unit (a) is preferably 20 to 99% by mass, more preferably 50 to 95% by mass, and even more preferably 60 to 90% by mass. If the content of the structural unit (a) is 20% by mass or more, the hydrophilicity of the copolymer is improved, and when formed into a coating film, the hydrophilicity of the coating film is improved. On the other hand, if the content of the structural unit (a) is 95% by mass or less, the hydrophilicity of the copolymer is not too high, and when formed into a coating film, the water resistance of the coating film is improved. The content of the structural unit (b) is preferably from 1 to 80 mass %, more preferably from 5 to 50%, and even more preferably from 10 to 40%. The total content of the structural unit (a) and the structural unit (b) in the hydrophilic copolymer of the present invention is preferably 51 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

[0025] The hydrophilic copolymer of the present invention may contain, in addition to the above-mentioned structural unit (a) and structural unit (b), a structural unit (c) represented by the following formula (4).

[0026] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0027] In the above formula (4), R 7 is a hydrogen atom or a methyl group, preferably a methyl group. X 3 is —NH— or —O—, preferably —O—. Y 1 is a group selected from the group consisting of a hydrogen atom, a hydroxyl group, a carboxyl group, an amino group, an isocyanate group, an epoxy group, an alkoxy group (—OR), and a hydrolyzable silyl group. Y 1 The alkoxy group (-OR) in R includes substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, specific examples of which include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, sec-butoxy, t-butoxy, n-pentyloxy, n-hexyloxy, cyclopentyloxy, cyclohexyloxy, etc. Some or all of the hydrogen atoms bonded to the carbon atoms of the alkyl group in R may be substituted with halogen atoms such as chlorine, fluorine, or bromine, or other substituents such as a cyano group. Y 1 Examples of the hydrolyzable silyl group include alkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, dimethoxysilyl, diethoxymethylsilyl, monomethoxydimethylsilyl, and monoethoxydimethylsilyl groups; carboxylate silyl groups such as acetoxysilyl groups; halosilyl groups such as trichlorosilyl, dichlorosilyl, and monochlorosilyl groups; aminosilyl groups; oximesilyl groups; and hydrosilyl groups. Among these, Y 1 is preferably a hydrogen atom or a hydroxyl group.

[0028] j is an integer of 0 to 10, preferably an integer of 0 to 6, more preferably an integer of 1 to 4, and even more preferably an integer of 2 to 4. However, when j is 0, Y 1 is a hydrogen atom.

[0029] When the hydrophilic copolymer of the present invention contains the structural unit (c), for example, the copolymer of the present invention and the Y 1 When a curing agent having a functional group capable of crosslinking with the copolymer is used in combination with the copolymer, a crosslinked structure can be formed between the curing agent and the copolymer. Furthermore, for example, when the copolymer of the present invention is used in combination with a curing catalyst such as an acid catalyst, the copolymer itself can undergo a crosslinking reaction (self-crosslinking). Therefore, a coating film formed from a composition containing the hydrophilic copolymer of the present invention and a curing agent has a crosslinked structure and can exhibit excellent water resistance.

[0030] From this point of view, in the above formula (4), Y 1 is more preferably a hydroxyl group. 1 When the copolymer of the present invention contains a structural unit (c) in which R is a hydroxyl group, for example, by combining the copolymer of the present invention with a curing agent having an isocyanate group, a crosslinked structure can be formed even under low-temperature conditions (for example, 110°C or lower). Therefore, a coating film can be formed from the composition of the present invention even on a substrate with low heat resistance.

[0031] Specific examples of the structural unit (c) represented by the above formula (4) include, but are not limited to, those represented by the following formulas.

[0032] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0033] When the hydrophilic copolymer of the present invention contains the structural unit (c), its content is not particularly limited, but is preferably 1 to 50 mass %, more preferably 3 to 20 mass %, and even more preferably 5 to 10 mass %.

[0034] The order of the constituent units contained in the hydrophilic copolymer of the present invention may be any order, and the copolymer of the present invention may be any of an alternating copolymer, a random copolymer, and a block copolymer.

[0035] The weight-average molecular weight of the hydrophilic copolymer of the present invention is not particularly limited, but from the viewpoint of improving affinity with organic solvents and hardness of the coating film, it is preferably 1,000 to 1,000,000, more preferably 5,000 to 700,000, even more preferably 300,000 to 600,000, and still more preferably 400,000 to 500,000. The weight-average molecular weight is measured by gel permeation chromatography (GPC) (standard substance: polystyrene, developing solvent: tetrahydrofuran).

[0036] Although there is no particular limitation on the viscosity of the hydrophilic copolymer of the present invention, from the viewpoints of compatibility with organic solvents and workability, it is preferably 0.01 to 0.5 Pa·s (at 25° C.) The viscosity is measured using a B-type rotational viscometer. The glass transition temperature of the hydrophilic copolymer is preferably −10 to 50° C. The glass transition temperature is a value measured in accordance with JIS K7121.

[0037] The hydrophilic copolymer of the present invention can be obtained by a known method. For example, as shown in the following scheme, in the presence of a polymerization initiator, a polymerizable monomer containing an isocyanate group, such as that represented by the following formula (5), is polymerized under an inert gas atmosphere such as nitrogen, and then an aminoalcohol represented by the following formula (6) and an organosilicon compound represented by the following formula (7) are reacted with each other under air or an inert gas atmosphere such as nitrogen.

[0038] [ka]

[0039] In the above formulas, R 1 ~R 5 , X 1 , X 2and n have the same meaning as above, h represents an integer of 1 to 10, g represents an integer of 1 to 3, Y 2 represents a functional group selected from the group consisting of -NH(R'), -SH, and -OH, R' represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a, b, and c are values ​​that ensure that the content of each structural unit falls within the above range. Examples of the alkyl group having 1 to 6 carbon atoms include the same as those mentioned above.

[0040] As the polymerizable monomer containing an isocyanate group of the above formula (5), commercially available products may be used, for example, Karenz (registered trademark) AOI manufactured by Showa Denko KK, and the like.

[0041] The polymerization initiator is preferably a thermal polymerization initiator, and the amount of the polymerization initiator added is preferably 0.5 to 30 mass %, more preferably 1 to 20 mass %, and even more preferably 2 to 10 mass %, based on the total mass of the monomers to be copolymerized. The polymerization initiator may be added all at once or in several portions.

[0042] Specific examples of the compound represented by formula (7) are shown below, but are not limited to these. Among these, the compound represented by formula (8) is preferred.

[0043] [ka] (In the formula, Me represents a methyl group, and Et represents an ethyl group.)

[0044] The above reaction can be carried out without a solvent, but can also be carried out in an organic solvent such as methyl ethyl ketone or 1,2-dimethoxyethane, if necessary, to the extent that the reaction is not inhibited. The reaction temperature is preferably from 0° C. to the boiling point of each solvent, more preferably from 20 to 80° C. The reaction time is preferably from 1 to 24 hours, more preferably from 5 to 10 hours.

[0045] The hydrophilic copolymer obtained by the above method can be blended with additives after adjusting the solid content concentration, exchanging the solvent, or filtering, as necessary. Alternatively, the hydrophilic copolymer produced by polymerization can be purified by precipitation or reprecipitation with hexane or the like, and then dissolved together with additives in a solvent appropriate for the application.

[0046] [2] Hydrophilic composition The hydrophilic composition of the present invention (hereinafter also simply referred to as "composition") contains one or more of the above-mentioned hydrophilic copolymers. The content of the hydrophilic copolymer contained in the composition of the present invention is not particularly limited, but from the viewpoint of hydrophilicity, it is preferably 1 to 50 mass % of the total composition, more preferably 5 to 25 mass %.

[0047] The composition of the present invention may contain other additives, etc., within the scope of not impairing the object of the present invention. Other additives include acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, oxalic acid, and maleic acid; alkalis such as ammonia, methylamine, and ethylamine; organic metal salts; Lewis acids; alkyltin ester compounds; leveling agents; surfactants, etc. Among these, the addition of organic metal salts allows for hardening at 25°C and 50% RH, and a highly durable hydrophilic film can be obtained.

[0048] The leveling agent and surfactant are contained to improve the uniformity of the coating film, and known ones can be used, with commercially available products being particularly preferred as they are easily available.

[0049] Examples of the organic metal salt include sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium formate, potassium formate, and tin octoate. Specific examples of Lewis acids include tetraisopropyl titanate, tetrabutyl titanate, aluminum triisobutoxide, aluminum triisopropoxide, aluminum acetylacetonate, tin chloride (SnCl4), titanium chloride (TiCl4), and zinc chloride (ZnCl4). Specific examples of alkyltin ester compounds include alkyltin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate, dioctyltin dioctoate, and dioctyltin diversatate. These may be used alone or in combination of two or more.

[0050] When the composition of the present invention contains an organometallic salt, the content thereof is preferably 0.05 to 50 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the hydrophilic copolymer.

[0051] The hydrophilic composition of the present invention may contain a solvent, if necessary. The solvent is not particularly limited as long as it can dissolve or disperse the hydrophilic copolymer and other additives, does not react with the other components, and can be easily removed in the drying step described below. Specific examples of the solvent include methanol, ethanol, isopropanol, tetrahydrofuran, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, ethyl acetate, ethyl lactate, methyl lactate, dimethyl sulfoxide, and water. These may be used alone or in combination of two or more.

[0052] The solid content concentration of the composition of the present invention is preferably 5 to 80% by mass, more preferably 10 to 30% by mass, from the viewpoints of coatability and workability. The viscosity of the composition of the present invention is preferably 0.01 to 0.05 Pa·s (at 25° C.) from the viewpoints of coatability and workability. The composition of the present invention may be a one-liquid type, or may be a type in which two or more liquids are mixed together before use.

[0053] The composition of the present invention can impart hydrophilicity to various substrates by applying it to them. Specific examples of materials constituting the substrate include glass; synthetic resins {polymethyl methacrylate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, ABS resin, polycarbonate resin, polystyrene resin, epoxy resin, unsaturated polyester resin, melamine resin, diallyl phthalate resin, polyimide resin, urethane resin, nylon resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, fluororesins (polytetrafluoroethylene resin, polychlorotrifluoroethylene resin, polyvinylidene fluoride resin, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer resin, ethylene tetrafluoroethylene copolymer resin, ethylene-chlorotrifluoroethylene copolymer resin, ethylene tetrafluoroethylene copolymer resin, ethylene ... ethylene copolymer resins, etc.), polybutadiene, polyisopropylene, SBR, nitrile rubber, EPM, EPDM, epichlorohydrin rubber, neoprene rubber, polysulfide, butyl rubber, etc.}; metals (iron, aluminum, stainless steel, titanium, copper, brass, alloys thereof, etc.); cellulose, cellulose derivatives, cellulose analogues (chitin, chitosan, porphyran, etc.), natural fibers such as cotton, silk, and wool, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, synthetic fibers such as vinylon, polyester, nylon, polyethylene, polypropylene, polyurethane, and polyaramid fibers; composite fibers of these fibers (polyester / cotton, etc.), and the like, can be used in the form of substrates, sheets, films, fibers, and various articles using these fibers.

[0054] The composition of the present invention can be applied to the surface of a substrate or the like to form a coating film, which can be used as a hydrophilic coating film. Examples of the coating method include bar coating, dip coating, spin coating, spray coating, float coating, brush coating, gravure coating, roll transfer, blade coating, air knife coating, slit coating, screen coating, inkjet printing, and flexographic printing. Of these, bar coating is preferred.

[0055] After applying the composition to a substrate, a cured coating film can be obtained by leaving it to stand at room temperature under atmospheric pressure for preferably 12 to 240 hours, more preferably 24 to 120 hours. Heating may also be performed to shorten the curing process. In this case, the heating temperature is preferably 40 to 250°C, more preferably 80 to 120°C. The heating time is preferably from 10 seconds to 12 hours, and more preferably from 30 seconds to 3 hours. The heating atmosphere may be either an air atmosphere or an inert gas (for example, nitrogen, argon, etc.) atmosphere.

[0056] The thickness of the coating film (dry film thickness) is not particularly limited, but is preferably 0.1 to 50 μm, more preferably 1 to 20 μm. [Example]

[0057] EXAMPLES The present invention will be explained in more detail below by showing examples and comparative examples, but the present invention is not limited to these examples.

[0058] (1) Preparation of hydrophilic copolymer [Example 1-1] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the following formula (9), and 0.72 g of oil-soluble azo polymerization initiator V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the following formula (10) were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 30.64 g of diethylene glycol monomethyl ether, 8.07 g of 3-aminopropyltrimethoxysilane, and 0.15 g of dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 164 g (solids concentration 43% by mass) of a 1,2-dimethoxyethane solution of hydrophilic copolymer P1 (content of structural unit (a) 85.0% by mass, content of structural unit (b) 15.0% by mass; weight average molecular weight 440,000).

[0059] [ka]

[0060] [Example 1-2] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of oil-soluble azo polymerization initiator V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the above formula (10) were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 40.01 g of dipropylene glycol monomethyl ether, 5.38 g of 3-aminopropyltrimethoxysilane, and 0.15 g of dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 176 g (solids concentration 44% by mass) of a 1,2-dimethoxyethane solution of hydrophilic copolymer P2 (content of structural unit (a) 90.0% by mass, content of structural unit (b) 10.0% by mass; weight average molecular weight 480,000).

[0061] [Examples 1-3] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of oil-soluble azo polymerization initiator V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the above formula (10) were added, and the mixture was reacted at 80°C for 4 hours. Next, 82.50 g of Uniox (registered trademark) M-550 (manufactured by NOF Corporation, average molecular weight 550) represented by the following formula (11), 26.89 g of 3-aminopropyltrimethoxysilane, and 0.15 g of dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70°C for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 234 g (solids concentration 58% by mass) of a 1,2-dimethoxyethane solution of hydrophilic copolymer P3 (content of structural unit (a) 50.0% by mass, content of structural unit (b) 50.0% by mass; weight average molecular weight 690,000).

[0062] [ka]

[0063] [Examples 1-4] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of oil-soluble azo polymerization initiator V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the above formula (10) were added, and the mixture was reacted at 80°C for 4 hours. Next, the heating of the reaction vessel was stopped, and 90.00 g of Uniox (registered trademark) M-1000 (manufactured by NOF Corporation, average molecular weight 1000) represented by the above formula (11), 37.65 g of 3-aminopropyltrimethoxysilane, and 0.15 g of dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the reaction was carried out at 70°C for 4 hours. After the reaction, the temperature of the solution in the reaction vessel was reduced to 25°C or less, and then the solution was filtered to obtain 257 g (solids concentration 59% by mass) of a 1,2-dimethoxyethane solution of hydrophilic copolymer P4 (content of structural unit (a) 30.0% by mass, content of structural unit (b) 70.0% by mass; weight average molecular weight 980,000).

[0064] [Examples 1-5] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), an oil-soluble azo polymerization initiator represented by the above formula (10), were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 30.64 g of diethylene glycol monomethyl ether, 8.84 g of 3-mercaptotrimethoxymethylsilane, and 0.15 g of dioctyltin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 165 g of a 1,2-dimethoxyethane solution (solids concentration: 44% by mass) of hydrophilic copolymer P5 (content of structural unit (a): 85.0% by mass, content of structural unit (b): 15.0% by mass; weight-average molecular weight: 460,000).

[0065] [Examples 1-6] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), an oil-soluble azo polymerization initiator represented by the above formula (10), were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 30.64 g of diethylene glycol monomethyl ether, 7.35 g of 3-aminopropyldimethoxymethylsilane, and 0.15 g of dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 162 g (solids concentration 43% by mass) of a 1,2-dimethoxyethane solution of hydrophilic copolymer P6 (content of structural unit (a) 85.0% by mass, content of structural unit (b) 15.0% by mass; weight average molecular weight 450,000).

[0066] [Comparative Example 1-1] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), an oil-soluble azo polymerization initiator represented by the above formula (10), were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 36.05 g of diethylene glycol monomethyl ether and 0.15 g of a dioctyl tin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had fallen to 25°C or below, the solution was filtered to obtain 166 g (solid concentration 43% by mass) of a 1,2-dimethoxyethane solution of hydrophilic polymer P7 (content of structural unit (a) 100.0% by mass; weight average molecular weight 490,000).

[0067] [Comparative Example 1-2] Into a reactor, 100.47 g of 1,2-dimethoxyethane, 42.34 g of Karenz (registered trademark) AOI (manufactured by Showa Denko K.K.) represented by the above formula (9), and 0.72 g of V-59 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), an oil-soluble azo polymerization initiator represented by the above formula (10), were added, and the mixture was reacted at 80°C for 4 hours. Subsequently, 8.17 g of methanol, 8.07 g of 3-aminopropyltrimethoxysilane, and 0.15 g of dioctyltin catalyst Neostan U-830 (manufactured by Nitto Kasei Co., Ltd.) were added, and the mixture was reacted at 70° C. for 4 hours. After the reaction, the heating of the reaction vessel was stopped, and after the temperature of the solution in the reaction vessel had dropped to 25°C or below, the solution was filtered to obtain 146 g (solid content concentration 41% by mass) of a 1,2-dimethoxyethane solution of copolymer P8 (weight average molecular weight 400,000).

[0068] (2) Preparation of coating composition (hydrophilic composition) [Example 2-1] A reactor was charged with 1.16 g of a 1,2-dimethoxyethane solution of the hydrophilic copolymer P1 obtained in Example 1-1, 0.84 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.), to obtain a yellow, transparent liquid (C1).

[0069] [Example 2-2] A reactor was charged with 0.86 g of a 1,2-dimethoxyethane solution of the hydrophilic copolymer P2 obtained in Example 1-2, 1.14 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.), to obtain a yellow, transparent liquid (C2).

[0070] [Example 2-3] A reactor was charged with 0.85 g of a methyl ethyl ketone solution of the hydrophilic copolymer P3 obtained in Example 1-3, 1.15 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.), to obtain a yellow, transparent liquid (C3).

[0071] [Example 2-4] Into a reactor, the hydrophilic copolymer P4 obtained in Example 1-4 was added. 1,2-Dimethoxyethane 0.85 g of the solution, 1.15 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a yellow, transparent liquid (C4).

[0072] [Example 2-5] Into a reactor, the hydrophilic copolymer P5 obtained in Example 1-5 was added. 1,2-Dimethoxyethane 1.14 g of the solution, 0.86 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a yellow, transparent liquid (C5).

[0073] [Example 2-6] Into a reactor, the hydrophilic copolymer P6 obtained in Examples 1-6 was added. 1,2-Dimethoxyethane 1.16 g of the solution, 0.84 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a yellow, transparent liquid (C6).

[0074] [Comparative Example 2-1] Into a reactor, the hydrophilic polymer P obtained in Comparative Example 1-1 was added. 7 of 1,2-Dimethoxyethane 1.16 g of the solution and 0.84 g of isopropanol were added to obtain a yellow, transparent liquid (C7).

[0075] [Comparative Example 2-2] In the reactor, the ethanol obtained in Comparative Example 1-2 jointly Polymer P 8 of 1,2-Dimethoxyethane 1.22 g of the solution, 0.78 g of isopropanol, and 0.02 g of titanium catalyst D-25 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a yellow, transparent liquid (C8).

[0076] [Comparative Example 2-3] In a reactor, 10 g of hydroxyl-containing acrylic resin ACRYL 6BF-100 (solid content concentration 40% by mass, manufactured by Taisei Fine Chemical Co., Ltd.) having a weight average molecular weight of 75,000, a hydroxyl value of 20 mg KOH / g, and a calculated glass transition temperature of 85 ° C., 0.65 g of Duranate TPA-100 (NCO content 23% by mass, manufactured by Asahi Kasei Corporation), 1.0 g of a methyl ethyl ketone solution of ACRYL 1WX (manufactured by Taisei Fine Chemical Co., Ltd.) (solid content concentration 40% by mass), which is a copolymer containing structural units represented by the following formulas (12), (13), (14), (15), and (16), and 13.6 g of methyl ethyl ketone were mixed to obtain a transparent yellow liquid (C9).

[0077] [ka] (In the formula, the asterisk * has the same meaning as above.)

[0078] (3) Preparation and evaluation of coating film [Examples 3-1 to 3-6, Comparative Examples 3-1 to 3-3] Each of the coating compositions C1 to C9 obtained in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-3 was applied to a polycarbonate plate using a bar coater (No. 14), and immediately dried at 120°C for 1 hour to obtain a coating.

[0079] [Examples 4-1 to 4-6, Comparative Examples 4-1 to 4-3] Each of the coating compositions C1 to C9 obtained in Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-3 above was applied to a polycarbonate plate using a bar coater (No. 14), and the plate was left to stand for 24 hours in an environment of 25°C and 50% RH to obtain a coating.

[0080] The coatings prepared in the above Examples and Comparative Examples were subjected to the following tests, and the results are shown in Tables 1 and 2. [Anti-fogging properties] Breath was blown onto each of the above coatings, and if the surface of the coating became cloudy, it was marked with an X, and if it did not become cloudy, it was marked with an O. Furthermore, the coating was placed above a 40°C warm water bath at a height of 3 cm above the water surface for 60 seconds, and if the surface of the coating did not become cloudy, it was marked with an ⊚ to evaluate the anti-fogging properties. [Water drip marks] In the anti-fogging evaluation, the coating film was left standing for 60 seconds above a 40°C warm water bath, after which it was air-dried for 10 minutes at 25°C. The surface was then illuminated with a 1,000 lm flashlight and visually inspected for signs of water dripping on the coating surface. If signs of water dripping were observed, it was rated as +, and if no signs of water dripping were observed, it was rated as -. [Hot water resistance] Each of the above coatings was immersed in warm water at 40°C for 24 hours, the water on the surface was absorbed with a paper wiper, and then the coating was air-dried at 25°C for 10 minutes, and the anti-fogging properties were evaluated. Subsequently, each coating was further immersed in warm water at 40°C for 216 hours, and after absorbing the water from the surface with a paper wiper, it was naturally dried at 25°C for 10 minutes, and the anti-fogging properties were evaluated. [Moisture resistance] Each of the coatings was left to stand for 24 hours in a thermo-hygrostat (KCL-2000W, Tokyo Rikakikai Co., Ltd.) set at 50°C and 98% RH, and then air-dried at 25°C for 10 minutes, after which the anti-fogging properties were evaluated. [Heat resistance] Each of the coatings was left standing for 24 hours in an incubator (SPHH-201, Espec Corp.) set at 120° C. Thereafter, it was left standing for 10 minutes at 25° C., and the anti-fogging properties were evaluated.

[0081] [Table 1]

[0082] [Table 2]

[0083] As shown in Tables 1 and 2, the coatings of Examples 3-1 to 3-6 and Examples 4-1 to 4-6 maintain excellent anti-fogging properties even after a hot water resistance test (24-hour immersion, 240-hour immersion), a moisture resistance test (50°C, 98% RH, 24 hours), and a heat resistance test (120°C, 24 hours). In particular, the coating of Example 3-1 is found to have excellent durability. On the other hand, the coatings of Comparative Examples 3-1, 3-3, 4-1, and 4-3 lost their anti-fogging properties after 24 hours of hot water immersion, indicating that these coatings had poor water resistance.Furthermore, the coating of Comparative Example 4-1 lost its anti-fogging properties after the heat resistance test, indicating that it had poor heat resistance.

Claims

1. A hydrophilic copolymer comprising a structural unit (a) represented by the following formula (1) and a structural unit (b) represented by the following formula (2): 【Chemistry 1】 (In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 is -(C 2 H 4 O) m -R 6 or -(C 3 H 6 O) m -R 6 m represents an integer of 1 to 50; R 6 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; X 1 represents a divalent linking group having one or more bonds selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond, In formula (2), R 3 represents a hydrogen atom or a methyl group, R 4 and R 5 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; X 2 represents a divalent linking group having one or more bonds selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond, n represents an integer of 1 to 3, and an asterisk * indicates a bond to an adjacent structural unit.

2. A hydrophilic composition comprising the hydrophilic copolymer of claim 1.

3. A coating obtained by curing the hydrophilic composition according to claim 2.

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