Hydrophilic polymer, hydrophilic coating, and hydrophilic substrate

Abstract

To provide a hydrophilic polymer that is capable of imparting excellent anti-fog performance, exhibiting superior durability, and inhibiting deposition of water scale, as well as a hydrophilic coating and a hydrophilic substrate having superior anti-fogging performance and durability with inhibited water scale deposition.SOLUTION: A hydrophilic polymer comprises a polymer chain having a structural unit A derived from a monomer component A having a betaine structure and a structural unit B derived from a monomer component B that is an activating compound, and a crosslinked structure having the polymer chains crosslinked with a crosslinking agent component C, as well as a hydrophilic coating and a hydrophilic substrate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to hydrophilic polymers, hydrophilic coatings, and hydrophilic substrates. [Background technology]

[0002] BACKGROUND ART Substrates such as glass, plastics, and polymer films are widely used as light transmitting or reflecting materials for lenses, bathroom or washstand mirrors, windows, and the like. Substrates used in the various materials described above require good visibility. Visibility can be impaired on the surface of a substrate due to light scattering caused by the adhesion or aggregation of water droplets. Reduced visibility leads to a deterioration in the functionality of the material. For example, mirrors installed in washrooms or bathrooms become cloudy due to water vapor, hindering their intended function. Display windows for frozen foods and other items are also prone to clouding due to condensation, making it difficult to see the interior of the display window. Furthermore, camera lenses used indoors and outdoors and lenses for medical devices used in endoscopic treatments and other procedures also suffer from significantly reduced visibility during use, making it difficult for the products to perform their intended functions.

[0003] In view of the above circumstances, in order to maintain the visibility of the substrate, attempts have been made to hydrophobize or hydrophilize the surface of the substrate to suppress fogging on the surface. For example, as a method of hydrophobizing the surface of the substrate, a technology has been disclosed in which a fluorine compound is used to impart water repellency to the surface, thereby suppressing moisture adhesion and suppressing fogging (e.g., Patent Document 1). Methods of hydrophilizing the surface of the substrate have also been disclosed (e.g., Patent Documents 2 and 3). By hydrophilizing the surface of the substrate, water is allowed to wet and spread on the surface of the substrate, forming a uniform water film on the surface, suppressing light scattering and making it possible to suppress fogging. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-038284 [Patent Document 2] Japanese Patent Publication No. 2023-124882 [Patent Document 3] Patent No. 7182750 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 has a problem in that water droplets gradually adhere to the surface in a high-humidity environment, impairing the anti-fogging performance. Also, the treatments for making the surface of the substrate hydrophilic as described in Patent Documents 2 and 3 have a problem in that the durability in a humid environment is poor because the surface is easily absorbed by water.

[0006] In addition, the buildup of limescale is another factor that impairs the visibility of substrates (glass, plastic, polymer film, etc.) used in lenses, bathroom or sink mirrors, windows, etc. Water that comes into contact with the substrate contains inorganic components such as silicate and calcium carbonate. Therefore, when water adheres to the substrate and then evaporates, the inorganic components remain on the surface, and a white coating forms as limescale. In this case, with the fluorine compound coating described in Patent Document 1, water droplets gradually adhere to the surface in a humid environment, causing stains due to the buildup of limescale. Furthermore, with the hydrophilic coatings described in Patent Documents 2 and 3, limescale gradually adheres, creating a scaly pattern on the surface, significantly impairing visibility.

[0007] The present disclosure has been made in light of the above. An object of one embodiment of the present disclosure is to provide a hydrophilic polymer that can impart excellent anti-fogging properties, has excellent durability, and can suppress the adhesion of water stains. Another problem to be solved by another embodiment of the present disclosure is to provide a hydrophilic coating material and a hydrophilic substrate that are excellent in anti-fogging properties and durability and that are inhibited from depositing water stains. [Means for solving the problem]

[0008] Specific means for solving the problems include the following aspects. <1> The hydrophilic polymer comprises a polymer chain having a constituent unit A derived from a monomer component A having a betaine structure and a constituent unit B derived from a monomer component B which is an active compound, and a crosslinked structure in which the polymer chains are crosslinked with a crosslinker component C. <2> The crosslinking agent component C is a hydrophilic crosslinking agent. <1> The hydrophilic polymer is described in <3> The hydrophilic crosslinking agent has an acrylamide skeleton. <2> The hydrophilic polymer is described in <4> the content Xc mass % of the hydrophilic crosslinking agent having an acrylamide skeleton, the content Xa mass % of the structural unit A, and the content Xb mass % of the structural unit B satisfy the relationship shown in the following formula (1): <3> The hydrophilic polymer is described in 0.0005≦Xc / (Xa+Xb)≦0.124 (1) <5> The content Xa% by mass and the content Xb% by mass of the structural unit B satisfy the relationship shown in the following formula (2): <4> The hydrophilic polymer is described in 3.8≦Xa / Xb≦167 (2) <6> Satisfy both the following formula (1-1) and the following formula (2-1): <5> The hydrophilic polymer is described in 0.0005≦Xc / (Xa+Xb)≦0.12 (1-1) 5.0≦Xa / Xb≦140 (2-1) <7> The betaine structure has an anion group selected from a carboxylic acid group, a sulfonic acid group, and a phosphate group, and a cation group selected from an ammonium group, a sulfonium group, and a phosphonium group. <1> ~ <6> The hydrophilic polymer is any one of the above. <8> The active compound has a functional group selected from a phosphonic acid group, a silanol group, and a group having a benzophenone skeleton. <1> ~ <7> The hydrophilic polymer is any one of the above. <9> <1> ~ <8> and water. <10> Furthermore, it contains a low molecular weight surfactant. <9> The hydrophilic coating material is as described in <11> A support; <9> or <10> and a coating film formed on the support using the hydrophilic coating material described in 1. above, the coating film having a static contact angle θ of 40° or less. <12> a support; and a substrate provided on the support. <9> or <10> and a coating film formed from the hydrophilic coating material described in 1. above, wherein the phosphoric acid index Px satisfies the following formula (3). 0.1≦Px≦7.0...Equation (3) [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, there is provided a hydrophilic polymer that can impart excellent anti-fogging properties, has excellent durability, and can suppress the adhesion of water stains. According to another embodiment of the present disclosure, there are provided a hydrophilic coating material and a hydrophilic substrate that are excellent in anti-fogging properties and durability and that are inhibited from forming water stains. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a photograph showing the state of water dropped onto the coated glass of Example 1 and the static contact angle. [Figure 2] 1 is a photograph showing the state of water dropped on uncoated glass and the static contact angle. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure will be described below. However, the present disclosure is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0012] In the present disclosure, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit. In this disclosure, the amount of each component means, for example, when a paint contains multiple substances corresponding to each component, the total amount of the multiple corresponding substances present in the paint, etc., unless otherwise specified. In this disclosure, "total solids" refers to the total mass of components excluding the solvent from the entire composition. Also, "solids" refers to the components excluding the solvent from the entire composition, and may be solid or liquid at 25°C, for example. Also, a combination of two or more preferred embodiments is a more preferred embodiment. It should be noted that "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

[0013] In the present disclosure, "hydrophilic" refers to a state in which a material exhibits a property (wettability with respect to water) of 45° or less in terms of contact angle with water, preferably 30° or less, and more preferably 10° or less. The contact angle is the angle formed between a water droplet of 1 μL to several μL and the surface of a material when the droplet is dropped onto the surface. A material with a small contact angle, i.e., a material that does not swell much with liquid and becomes flat, is easily wetted, while a material that swells much with liquid and becomes nearly spherical, is difficult to wet. A material that is easily wetted has high wettability, while a material that is difficult to wet has low wettability. The contact angle with water is a value measured according to a method in accordance with Japanese Industrial Standard (JIS) R3257:1999 and can be measured using a contact angle meter (for example, the DMs-401 contact angle meter, manufactured by Kyowa Interface Science Co., Ltd.).

[0014] (hydrophilic polymer) The hydrophilic polymer of the present disclosure comprises a polymer chain having a constituent unit A derived from a monomer component A having a betaine structure and a constituent unit B derived from a monomer component B that is an active compound, and a crosslinked structure in which the polymer chains are crosslinked with a crosslinker component C.

[0015] [Polymer chain] The polymer chain constituting the hydrophilic polymer contains a polymer chain having a structural unit A derived from a monomer component A having a betaine structure and a structural unit B derived from a monomer component B that is an active compound.

[0016] -Constituent Unit A- The hydrophilic polymer of the present disclosure contains a structural unit A derived from a monomer component A having a betaine structure. The structural unit A refers to a divalent unit formed by removing two hydrogen atoms from the monomer component A. The inclusion of a structure derived from the monomer component A results in the formation of a betaine structure, and when the polymer is formed on the surface of a substrate, such as a glass or resin substrate, it turns fine condensation droplets into a water film. As a result, light scattering is reduced, thereby imparting anti-fogging properties to the substrate surface.

[0017] <Monomer component A> Monomer component A is a betaine compound having a betaine structure and has a hydrophilic function. A betaine structure is a zwitterionic compound that has a positively charged moiety and a negatively charged moiety at non-adjacent positions within the same molecule, and is electrically neutral as a whole. Examples of the positively charged moiety include quaternary amines, sulfonium, and phosphonium groups, and examples of the negatively charged moiety include carboxylic acid, sulfonic acid, and phosphoric acid groups.

[0018] The betaine structure preferably has an anionic group selected from a carboxy group, a sulfo group, and a phosphate group, and a cationic group selected from an ammonium group, a sulfonium group, and a phosphonium group.

[0019] Examples of the monomer component A include phosphobetaine types such as 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine types such as 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propane-1-sulfonic acid, and carboxybetaine types such as 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate and 3-[(3-acrylamidopropyl)dimethylammonio]propanoate. Among these, 2-methacryloyloxyethyl phosphorylcholine is preferred.

[0020] -Constituent Unit B- The hydrophilic polymer of the present disclosure contains a structural unit B derived from a monomer component B, which is an active compound. The structural unit B refers to a divalent unit formed by removing two hydrogen atoms from the monomer component B. The active compound refers to a compound that forms a bond with the substrate surface through a physical or chemical bond with the substrate surface, regardless of the presence or absence of physical or chemical stimulation. Because the active compound contains a structure derived from the active compound (monomer component B), it can form a physical or chemical bond with the substrate surface. As a result, durability can be imparted to the coating film formed on the substrate surface.

[0021] <Monomer component B> Suitable examples of the monomer component B (active compound) include compounds having at least one functional group selected from a phosphonic acid group, a silanol group, a catechol group, a thiol group, a group having a benzophenone skeleton, a group having a diazirine skeleton, and a group having a phenyl azide skeleton, and more preferred are compounds having a functional group selected from a phosphonic acid group, a silanol group, and a group having a benzophenone skeleton.

[0022] The phosphonic acid group is preferably an ester group having a polymerizable double bond. As the compound having a phosphonic acid group, a phosphate ester containing an ester group having a polymerizable double bond is preferred, and a phosphate ester containing an ester group having two or more polymerizable double bonds is more preferred. As the phosphate ester containing an ester group having a polymerizable double bond, commercially available products can be used, and examples of commercially available products include Light Ester P-1M and Light Ester P-2M (both manufactured by Kyoeisha Chemical), and the Phosmer series (trade names: for example, Phosmer M, Phosmer PE, Phosmer MH, Phosmer PP, etc., manufactured by Unichemical Co., Ltd.). Among them, Phosmer M is preferred.

[0023] The group having a benzophenone skeleton is capable of becoming highly reactive in a triplet excited state upon irradiation with light, and can form bonds by abstracting hydrogen atoms from the substrate or copolymer. Examples of compounds having a group having a benzophenone skeleton (benzophenone skeleton-containing monomers) include 4-acryloyloxybenzophenone, 4-methacryloyloxybenzophenone (MBP), 4-acryloyloxy-2-hydroxybenzophenone, 4-methacryloxy-2-hydroxybenzophenone (MHP), and 4-benzoylphenyl methacrylate.

[0024] The compound having a catechol group preferably has a polymerizable double bond, such as N-(3,4-dihydroxyphenethyl)methacrylamide or 4-allylpyrocatechol.

[0025] Examples of compounds having a silanol group include 3-(trimethoxysilyl)propyl methacrylate, 3-(triethoxysilyl)propyl methacrylate, 3-(trimethoxysilyl)octyl methacrylate, 3-(diethoxymethoxysilyl)propyl methacrylate, 3-(ethoxydimethoxysilyl)propyl methacrylate, 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate, 3-(trimethoxysilyl)propyl acrylate, 3-(triethoxysilyl)propyl acrylate, 3-(trimethoxysilyl)octyl acrylate, and 3-(diethoxymethoxysilyl)propyl acrylate, 3-(ethoxydimethoxysilyl)propyl acrylate, 3-(methyldimethoxy)propyl methacrylate, 3-(diethoxymethyl)propyl methacrylate, 3-(ethyldimethoxy)propyl methacrylate, 3-(ethyldiethoxy)propyl methacrylate, 3-(ethoxymethylmethoxy)propyl methacrylate, 3-(methyldimethoxy)propyl acrylate, 3-(diethoxymethyl)propyl methylacrylate, 3-(ethyldimethoxy)propyl acrylate, 3-(ethyldiethoxy)propyl acrylate, 3-(ethoxymethylmethoxy)propyl acrylate.

[0026] The ratio (Xa / Xb) of the content Xa% by mass of the structural unit A to the content Xb% by mass of the structural unit B preferably satisfies the following formula (2), preferably the following formula (2-1), and more preferably the following formula (2-2). 3.8≦Xa / Xb≦167 (2) 5.0≦Xa / Xb≦140 (2-1) 12≦Xa / Xb≦102 (2-2)

[0027] When Xa / Xb is 3.8 or more, a coating film with higher durability can be obtained, and the adhesion of water stains can be more effectively prevented.When Xa / Xb is 167 or less, abrasion resistance is high, and durability is more effectively improved.

[0028] The hydrophilic polymer in the present disclosure may further contain a structural unit derived from another monomer in addition to the structural unit A and the structural unit B, as long as the effects of the present invention are not significantly impaired. A structural unit derived from another monomer refers to a divalent unit obtained by removing two hydrogen atoms from another monomer. Examples of other monomers include polyfunctional acrylates having an acrylamide skeleton, (meth)acrylates having a linear alkyl group, (meth)acrylates having a branched alkyl group, (meth)acrylates having an acid group, (meth)acrylates having a cyclic aliphatic group, (meth)acrylates having an oxo group, (meth)acrylates having a fluorine atom, (meth)acrylates having a nitrogen atom, (meth)acrylates having an epoxy group, (meth)acrylates having a carbonyl group, and (meth)acrylates having an addition-polymerizable oxazoline.

[0029] [Crosslinked structure] The hydrophilic polymer of the present disclosure includes a crosslinked structure in which polymer chains containing the structural unit A and the structural unit B are crosslinked with a crosslinker component C. The polymer chains in the hydrophilic polymer are chemically crosslinked with each other by the crosslinker component, thereby imparting durability and providing anti-scale adhesion ability. The reason for this effect is not entirely clear, but is presumed to be as follows. Chemical crosslinking of polymer chains containing the structural unit A and the structural unit B reduces the distance between the polymer chains, forming a network polymer structure with a high density network. This network polymer structure reduces the frequency with which inorganic components that cause limescale adhere to the substrate, and the active compounds densely present in the network polymer reduce the number of active sites on the substrate surface, thereby suppressing the deposition of inorganic components on the substrate. Additionally, the presence of a betaine structure in the network polymer hydrates non-deposited inorganic components with water molecules (free water) with relatively high molecular mobility, preventing their deposition on the substrate surface. Furthermore, even after water evaporates from the coating film, the inorganic components are thought to weakly adsorb within the network polymer rather than onto the substrate surface, allowing them to be washed off by applying water again. This cycle achieves limescale prevention.

[0030] The crosslinked structure can be determined by immersing the sample in ethanol or pure water as a single solvent, or a mixed solvent of ethanol and pure water in a 1:1 ratio for 5 minutes, and if the sample remains undissolved, it can be determined that a crosslinked structure has been formed.

[0031] <Crosslinking agent component C> A hydrophilic crosslinking agent is preferred as the crosslinking agent component C. The use of a hydrophilic crosslinking agent forms a network structure with a high water content, which improves durability and improves the ability to prevent the adhesion of water stains.

[0032] Examples of hydrophilic crosslinking agents include hydrophilic crosslinkers having an acrylamide skeleton and hydrophilic crosslinkers having an alkylene glycol ester skeleton (e.g., (meth)acrylic acid alkylene glycol esters (polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, etc.), poly(meth)acrylic esters of polyvinyl alcohol). Among these, hydrophilic crosslinkers having an acrylamide skeleton are preferred from the viewpoint of keeping the contact angle low and further improving durability. Among water-soluble crosslinking agents, hydrophilic crosslinkers having an acrylamide skeleton have high hydrophilicity and excellent hydrolysis resistance, thereby improving durability. In addition, by imparting appropriate molecular mobility to the network structure, the molecular mobility of water within the coating film is improved, making it less likely that inorganic components contained in scale will deposit. This reduces the amount of scale buildup.

[0033] Examples of hydrophilic crosslinking agents having an acrylamide skeleton include N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide, N,N-bis(2-acrylamidoethyl)acrylamide, N,N'-[oxybis(2,1-ethanediyloxy-3,1-propanediyl)]bisacrylamide, N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide}, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N,N-dimethylaminomethyl(meth)acrylamide. )acrylamide, N,N-diethylaminomethyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N,N-dimethylaminohexyl(meth)acrylamide, N,N-diethylaminohexyl(meth)acrylamide, N,N-dihexyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide N,N'-methylenebis(meth)acrylamide, N,N'-ethylenebis(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, Nt-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-dodecyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-ethoxy Dimethyl (meth)acrylamide, N-ethoxyethyl (meth)acrylamide, N-butoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, N-alkoxyalkyl (meth)acrylamide, 6-(meth)acrylamidohexanoic acid, (meth)acrylamide, (meth)acryloylmorpholine, N-hydroxymethyl (meth)acrylamide, N-2-hydroxyethyl (meth)acrylamide, N-2-hydroxypropyl (meth)acrylamide, N-3,Examples of suitable hydrophilic crosslinking agents having an acrylamide skeleton include 4-dihydroxyphenethyl(meth)acrylamide, N-carbamoylmethyl(meth)acrylamide, 6-(meth)acrylamidohexanoic acid, diallylamine, N-vinylpyrrolidone, diacetone acrylamide, vinylacetamide, N-propylprop-2-enamide, and N-hydroxyethyl-N-methyl(meth)acrylamide. Commercially available hydrophilic crosslinking agents having an acrylamide skeleton may be used. Examples of commercially available products include water-soluble acrylamide crosslinking agents manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (e.g., FOM-03006, FOM-03007, FOM-03008, FOM-03009, etc.), and the high-purity powder type acrylamide series manufactured by Kanto Chemical Co., Ltd. (e.g., Acrylamide HGX, N,N'-methylenebisacrylamide HGX, etc.).

[0034] When the content of the hydrophilic crosslinking agent having an acrylamide skeleton is Xc mass %, the content of the structural unit A derived from the monomer component A having a betaine structure is Xa mass %, and the content of the structural unit B derived from the monomer component B which is an active compound is Xb mass %, it is preferable that the relationship shown in the following formula (1) is satisfied, it is more preferable that the relationship shown in the following formula (1-1) is satisfied, and it is more preferable that the relationship shown in the following formula (1-2) is satisfied. 0.0005≦Xc / (Xa+Xb)≦0.124 (1) 0.0005≦Xc / (Xa+Xb)≦0.12 (1-1) 0.0005≦Xc / (Xa+Xb)≦0.115 (1-2)

[0035] When Xc / (Xa+Xb) is 0.0005 or more, the durability and friction and abrasion resistance are improved and a hydrophilic coating film with higher anti-scale ability can be obtained.When Xc / (Xa+Xb) is 0.124 or less, a hydrophilic coating film with high durability and friction and abrasion resistance can be obtained while maintaining anti-fogging properties and anti-scale ability.

[0036] ~Synthesis of hydrophilic polymers~ The hydrophilic polymer can be synthesized by mixing a hydrophilic monomer (monomer component A), an active compound (monomer component B), a crosslinker component C, and optionally a polymerization initiator, and then carrying out a polymerization reaction. It is preferable to dissolve the monomer in the reaction solvent so that the monomer concentration is 0.1 mol / L to 1.0 mol / L. The polymerization reaction may also be carried out by heating after the above mixing.

[0037] As the polymerization initiator, a conventionally known polymerization initiator can be appropriately selected and used. The polymerization initiator may be either a thermal polymerization initiator or a photopolymerization initiator, with a thermal polymerization initiator being preferred. Examples of the thermal polymerization initiator include azo-based initiators (e.g., 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazoline-2-yl]-2-methylpropionate] ...4,4'-azobis[2-(5-methyl-2-imidazoline-2-yl]-2-methylpropionate], 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 4,4'-azobis(2-(5-methyl-2-imidazoline-2-yl)propionate], 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 4,4'-azobis(2-(5-methyl-2-imidazoline-2-yl)propionate], 4,4'-azobi [N,N'-dimethyleneisobutylamidine]dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, etc. are preferred, and for example, V-601 (trade name) or V-65 (trade name) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. can be used.

[0038] The content of the polymerization initiator relative to the total amount of the monomer component A, the monomer component B, and the crosslinking agent component C is preferably 0.68% by mass to 1.56% by mass, and more preferably 0.75% by mass to 1.47% by mass.

[0039] (hydrophilic paint) The hydrophilic coating material of the present disclosure contains the hydrophilic polymer of the present disclosure and water. The hydrophilic coating material of the present disclosure preferably further contains a low-molecular-weight surfactant, and may contain other components as needed. The details of the hydrophilic polymer of the present disclosure are as described above, and therefore will not be described here.

[0040] -water- The hydrophilic coating of the present disclosure contains water. Examples of water include pure water and ion-exchanged water.

[0041] The content of water in the hydrophilic coating material is preferably 98.75 mass % to 99.9 mass %, more preferably 99.5 mass % to 99.75 mass %, relative to the total mass of the hydrophilic coating material.

[0042] -Low molecular weight surfactants- The hydrophilic coating material of the present disclosure preferably contains a low-molecular-weight surfactant, which reduces the surface free energy of the hydrophilic coating material, improving film-forming properties on substrates and further enhancing the anti-fogging properties of the surface while improving the durability of the anti-fogging performance.

[0043] The term "low molecular weight" refers to a surfactant with a molecular weight of 1000 or less. The molecular weight can be calculated from the formula weight.

[0044] The low-molecular surfactant may be selected from the group consisting of ionic surfactants and nonionic surfactants, preferably nonionic surfactants or anionic surfactants, and more preferably anionic surfactants. Examples of anionic surfactants include sodium decylbenzenesulfonate, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, potassium stearate, and calcium oleate.

[0045] The content of the low molecular weight surfactant is preferably 0.0001% by mass to 0.5% by mass, and more preferably 0.001% by mass to 0.1% by mass, relative to the total mass of the hydrophilic coating material.

[0046] -Other ingredients- Other components that can be contained in the hydrophilic coating material include, for example, pigments, film-forming aids, fillers, wetting agents, antistatic agents, pigment dispersants, antioxidants, leveling agents, viscosity modifiers, antifoaming agents, ultraviolet absorbers, dispersants, etc.

[0047] The hydrophilic coating material of the present disclosure can be prepared by mixing the hydrophilic polymer of the present disclosure described above, water, and, if necessary, a low-molecular surfactant and other components.

[0048] (Hydrophilic base material) <First embodiment of hydrophilic substrate> The hydrophilic substrate according to the first embodiment of the present disclosure has a support and a coating film formed on the support using the aqueous coating material of the present disclosure described above, the coating film having a static contact angle θ of 40° or less. The details of the water-based paint of the present disclosure are as described above, and therefore will not be described here.

[0049] -Support- The support may be selected from conventionally known substrates, such as glass substrates, metal substrates, and plastic substrates.

[0050] -Paint film- The hydrophilic substrate of the present disclosure has a coating film formed by applying the above-described water-based coating material of the present disclosure onto a support. The coating film contains the solid content contained in the water-based coating material.

[0051] From the viewpoint of achieving superior anti-fogging properties, the static contact angle θ of the coating film is 40° or less, preferably 30° or less, more preferably 20° or less, and even more preferably 10° or less. The lower the static contact angle θ of the coating film, the better, but the lower limit may be, for example, 2°.

[0052] The static contact angle θ is a value measured by a method conforming to Japanese Industrial Standards (JIS) R3257:1999. For example, pure water is dropped onto the coating surface of a hydrophilic substrate, and the static contact angle θ can be measured using a contact angle meter (e.g., contact angle meter DMs-401, manufactured by Kyowa Interface Science Co., Ltd.).

[0053] The coating film can be formed by a conventionally known coating method, such as bar coating, roll coating, curtain coating, air knife coating, gravure coating, dipping, or inkjet coating.

[0054] The thickness of the coating film is preferably 0.5 nm to 1000 nm, more preferably 5 nm to 500 nm, and more preferably 10 nm to 300 nm.

[0055] <Second embodiment of hydrophilic substrate> The hydrophilic substrate according to the second embodiment of the present disclosure has a support and a coating film formed on the support using the aqueous coating material of the present disclosure described above, the coating film having a phosphorus index Px that satisfies the following formula (3): 0.1≦Px≦7.0...Equation (3)

[0056] The details of the water-based paint of the present disclosure are as described above, and therefore will not be described here. The details of the support and the coating film (excluding Px) are the same as those in the first embodiment.

[0057] The phosphoric acid index Px of the coating film is within a range that satisfies the following formula (3), preferably within a range that satisfies formula (3-1), and more preferably within a range that satisfies formula (3-2). 0.1≦Px≦7.0...Equation (3) 0.1≦Px≦4.0...Equation (3-1) 0.1≦Px≦2.0...Equation (3-2)

[0058] The phosphate index Px is evaluated in the following way. The hydrophilic substrate is irradiated with X-rays using a scanning X-ray photoelectron spectrometer (e.g., Quantera SXM manufactured by ULVAC-PHI, Inc.) and surface analysis is performed to measure the phosphorus atom content (atomic %), which is used to evaluate Px. The threshold value for the phosphorus atom content is 0.1 atomic %, and a content of 0.1 atomic % or more is preferred. -Measurement conditions- X-ray: monochromated AlKα Output: 25W X-ray probe diameter: 100 μm Pass energy: 280 eV measurement condition [Example]

[0059] The present invention will be explained in more detail below using examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. Unless otherwise specified, "parts" are based on mass. In addition, "-" in the tables indicates that the component is not contained.

[0060] Details of the components used in the examples and comparative examples are shown below.

[0061] (Hydrophilic Monomer (Monomer Component A)) MPC: 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0062] FOM-03010: Fujifilm Wako Pure Chemical Industries, Ltd. [ka]

[0063] 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propane-1-sulfonic acid, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0064] 4-[(3-methacrylamidopropyl)dimethylammonio]butane-1-sulfonic acid, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0065] 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0066] (Other hydrophilic monomers) 2-Methoxyethyl acrylate, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0067] (Active compound (monomer component B)) Hosmer M: Manufactured by Unichemical [ka]

[0068] 3-(Trimethoxysilyl)propyl methacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0069] N-(3,4-dihydroxyphenethyl) methacrylamide, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0070] 4-Benzoylphenyl methacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. [ka]

[0071] (Crosslinking agent component C) FOM-03006: N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (hydrophilic crosslinker) FOM-03007: N,N-bis(2-acrylamidoethyl)acrylamide, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (hydrophilic crosslinker) FOM-03008: N,N'-[oxybis(2,1-ethanediyloxy-3,1-propanediyl)]bisacrylamide, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (hydrophilic crosslinker) FOM-03009: N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide}, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (hydrophilic crosslinker) PEG400 diacrylate: Daicel Allnex Corporation (hydrophilic crosslinking agent) 1,6-Hexanediol Dimethacrylate: 1,6-Hexanediol Diacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. (non-hydrophilic crosslinking agent)

[0072] (Polymerization initiator) V-601: 2,2'-azobis(2-methylpropionate) dimethyl, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0073] Example 1 -Synthesis of hydrophilic polymers- As a hydrophilic monomer, MPC (2-methacryloyloxyethyl phosphorylcholine; C 11 H 22 NO6P, Mw=295.27, CAS 67881-98-5 (monomer component A) and Phosmer M (Acid phosphoxy ethylmethacrylate; CH 11 O6P, Mw=210.12, CAS 24599-21-1; monomer component B) and FOM-03008 (N,N'-Diacryloyl-4,7,10-Trioxa-1,13-Tridecanediamine; C) as a crosslinker component. 16 H 28N2O5, Mw=328.41, CAS 160432-07-5; crosslinker component C) and radical polymerization initiator V-601 (Dimethyl 2,2'-azobis(2-methylpropionate, C 10 H 18 N2O4, Mw=230.26, CAS 2589-57-3) were mixed in the amounts (parts by mass) shown in Table 1 and dissolved at 25°C so that the monomer concentration in pure water, the reaction solvent, was 0.1 mol / L to 1.0 mol / L. The mixture was then heated at 75°C for 5 hours to obtain a polymer solution (a solution of a hydrophilic polymer). The obtained polymer was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check its dissolution state. As a result, it remained undissolved, confirming that a crosslinked structure had been formed.

[0074] -Preparation of hydrophilic paints and coatings- Pure water was added to the obtained polymer solution to adjust the amount of polymer contained to 1% by mass, thereby preparing a coating material (hydrophilic paint).

[0075] A glass slide (support) was immersed in the prepared coating material for 30 minutes, then removed from the coating material, washed with pure water, and dried to produce a coated glass (hydrophilic substrate) with the surface of the glass slide coated with the coating material.

[0076] -Measurement and Evaluation- The coated glass prepared as described above was subjected to the following measurements and evaluations, and the results are shown in Table 1 below.

[0077] (1) Measurement of static contact angle θ Pure water was dropped onto the coated glass surface, and measurements were taken at three locations per sample using a contact angle meter DMs-401 manufactured by Kyowa Interface Science Co., Ltd. (purified water drop volume: 2.0 μL, drop measurement time: 1000 ms). The average of the measured values ​​was calculated and evaluated according to the following criteria. -standard- A: The contact angle is 10° or less. B: The contact angle is more than 10° and not more than 30°. C: The contact angle is greater than 30° and equal to or less than 45°. D: The contact angle is greater than 45°.

[0078] (2) Wet anti-fogging test (anti-fogging property) The surface of the prepared coated glass was wetted with water and then placed horizontally at a position 50 mm above the surface of 90°C warm water. 300 seconds after placement, the presence or absence of fogging on the coated glass was visually evaluated according to the following criteria. -standard- A: No fogging due to water vapor is observed. B: Cloudiness due to water vapor is observed.

[0079] The static contact angle θ of the coated glass produced in Example 1 was 4.4°. The state of the liquid film of the dropped pure water at this time is shown in Figure 1. Note that Figure 2 is a photograph showing the state of the liquid film (static contact angle θ > 10°) when pure water was dropped on a slide glass (support) before coating.

[0080] (3) Durability evaluation The surface of the coated glass thus prepared was wetted with water, and then the coated surface of the coated glass and a urethane sheet were brought into contact with each other and moved back and forth 1,000 times using a surface property measuring instrument (HEIDON TYPE: 38) manufactured by Shinto Scientific Co., Ltd., under conditions of a load of 100 g and a pulling speed of 60 cm / min, and the anti-fogging properties were then evaluated according to the following criteria. -standard- A: No fogging due to water vapor is observed. B: Slight cloudiness is observed on the surface. C: Cloudiness due to water vapor is observed.

[0081] (4) Water stain prevention (water stain test) Hard water (product name: Evian, Ito En Co., Ltd.) was sprayed onto the coated glass using a spray bottle approximately 20 cm away from the coated plate so that droplets were evenly distributed across the plate. The plate was then dried in a hot air dryer at 60°C for 10 minutes to allow the scale to adhere to the coating. The coating was then washed with pure water and the remaining scale was visually evaluated according to the following criteria. -standard- A: The scale is not solidified. B: Most of the limescale is removed by washing, or small spots remain. C: Water stains were stuck to the ring like coffee rings, and the appearance quality was unacceptable.

[0082] (5) Friction and wear resistance The coated surface of the prepared coated glass was rubbed with a urethane sheet to perform an abrasion treatment on the surface, and the same evaluation as in "(2) Wet anti-fogging test (anti-fogging properties)" was carried out to count the number of rubs until fogging occurred, and the results were evaluated according to the following criteria. -standard- A: Over 1000 times B:700~999 times C: 400 to 699 times D: 100 to 399 times E: 0 to 99 times

[0083] (6) Phosphate index Px The surface of the coated glass was analyzed using a scanning X-ray photoelectron spectrometer (Quantera SXM, manufactured by ULVAC-PHI, Inc.) under the following measurement conditions: monochromatic AlKα X-ray irradiation, output power of 25 W, X-ray probe diameter of 100 μm, and pass energy of 280 eV. The phosphorus atom content (atomic %) was determined as the phosphate index Px. -standard- A: The P (phosphorus) content is 0.1 atomic % or more. B: P (phosphorus) cannot be detected.

[0084] Examples 2 to 5 In Example 1, except that the type of hydrophilic monomer (monomer component A) was changed as shown in Table 1, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 2 to 5, the same liquid film state as in FIG. 1 was observed.

[0085] (Examples 6 to 7) In Example 1, except that the type of active compound (monomer component B) was changed as shown in Table 1, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was prepared, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 6 and 7, the same liquid film state as in FIG. 1 was observed.

[0086] Example 8 A polymer solution (a solution of a hydrophilic polymer) was obtained in the same manner as in Example 1, except that the type of active compound (monomer component B) in Example 1 was changed as shown in Table 1. The obtained polymer was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check its dissolution state. As a result, it remained undissolved, confirming that a crosslinked structure had been formed. Then, pure water was added to the obtained polymer solution to adjust the amount of polymer contained therein to 1% by mass, thereby preparing a coating material (hydrophilic paint). A polycarbonate sheet (support) was immersed in the prepared coating material for 5 minutes, the support was removed from the coating material, dried, and then cured by irradiating with 365 nm ultraviolet light. The support was then washed with pure water and dried to produce a coated glass (hydrophilic substrate) in which the surface of the polycarbonate sheet was coated with the coating material. Measurements and evaluations were then carried out in the same manner as in Example 1.

[0087] Examples 9 to 13 In Example 1, except that the type of crosslinker component C was changed as shown in Table 1, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was prepared, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 9 to 13, the same liquid film state as in FIG. 1 was observed.

[0088] (Examples 14 to 21) In Example 1, except that the content of the crosslinking agent was changed as shown in Table 1, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 14 to 21, the same liquid film state as in FIG. 1 was observed.

[0089] Examples 22 to 29 In Example 1, except that the content of the active compound (monomer component B) was changed as shown in Table 1, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was prepared, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 22 to 29, the same liquid film state as in FIG. 1 was observed.

[0090] Example 30 Coated glass was produced in the same manner as in Example 1, except that the coating material (hydrophilic paint) was prepared by further using a surfactant (sodium dodecyl sulfate) shown in Table 2, and further measurements and evaluations were carried out. When pure water was dropped onto the coated glass produced in Example 30, a liquid film state similar to that shown in FIG. 1 was observed.

[0091] (Examples 31 to 33) In Example 1, except that the contents of the hydrophilic monomer (monomer component A), monomer component B, and monomer component C were changed as shown in Table 2, a polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and further measurements and evaluations were carried out in the same manner as in Example 1. Each of the obtained polymers was immersed in a mixed solvent of ethanol and pure water in a 1:1 (mass ratio) for 5 minutes to check the state of dissolution. As a result, it was confirmed that the polymers remained undissolved, and that a crosslinked structure had been formed. When pure water was dropped onto the coated glasses produced in Examples 31 to 33, the same liquid film state as in FIG. 1 was observed.

[0092] (Comparative Example 1) A polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and further measurements and evaluations were carried out in the same manner as in Example 1, except that the hydrophilic monomer (monomer component A) in Example 1 was changed to the component shown in Table 2.

[0093] (Comparative Example 2) A polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and further measurements and evaluations were carried out in the same manner as in Example 1, except that the active compound (monomer component B) in Example 1 was not used.

[0094] (Comparative Example 3) A polymer solution (a solution of a hydrophilic polymer) was obtained, a coated glass was produced, and measurements and evaluations were carried out in the same manner as in Example 1, except that the crosslinking agent component C in Example 1 was not used.

[0095] [Table 1]

[0096] [Table 2]

[0097] [Table 3]

[0098] As shown in Tables 1 to 3, in Examples, the static contact angle was kept low compared to Comparative Examples 1 to 3, and the samples exhibited excellent anti-fogging performance, durability, and friction and abrasion resistance.

Claims

1. A hydrophilic polymer comprising a polymer chain having a structural unit A derived from a monomer component A having a betaine structure and a structural unit B derived from a monomer component B which is an active compound, and a crosslinked structure in which the polymer chains are crosslinked with a crosslinker component C.

2. The hydrophilic polymer according to claim 1, wherein the crosslinking agent component C is a hydrophilic crosslinking agent.

3. The hydrophilic polymer according to claim 2 , wherein the hydrophilic crosslinking agent has an acrylamide skeleton.

4. 4. The hydrophilic polymer according to claim 3, wherein the content Xc% by mass of the hydrophilic crosslinking agent having an acrylamide skeleton, the content Xa% by mass of the structural unit A, and the content Xb% by mass of the structural unit B satisfy the relationship shown in the following formula (1): 0.0005≦Xc / (Xa+Xb)≦0.124 (1)

5. The hydrophilic polymer according to claim 4 , wherein the content Xa (% by mass) and the content Xb (% by mass) of the structural unit B satisfy the relationship shown in the following formula (2): 3.8≦Xa / Xb≦167 (2)

6. 6. The hydrophilic polymer according to claim 5, which satisfies both the following formula (1-1) and the following formula (2-1): 0.0005≦Xc / (Xa+Xb)≦0.12 (1-1) 5.0≦Xa / Xb≦140 (2-1)

7. 2. The hydrophilic polymer according to claim 1, wherein the betaine structure has an anionic group selected from a carboxylic acid group, a sulfonic acid group, and a phosphate group, and a cationic group selected from an ammonium group, a sulfonium group, and a phosphonium group.

8. 2. The hydrophilic polymer according to claim 1, wherein the active compound has a functional group selected from the group consisting of a phosphonic acid group, a silanol group, a catechol group, and a group having a benzophenone skeleton.

9. A hydrophilic coating material comprising the hydrophilic polymer according to any one of claims 1 to 8 and water.

10. The hydrophilic coating material according to claim 9, further comprising a low molecular weight surfactant.

11. A support; a coating film formed on the support using the hydrophilic coating material according to claim 9, the coating film having a static contact angle θ of 40° or less; A hydrophilic substrate having

12. A hydrophilic substrate comprising: a support; and a coating film provided on the support, the coating film being formed from the hydrophilic coating material according to claim 9, and having a phosphorus index Px that satisfies the following formula (3): 0.1≦Px≦7.0 ...Formula (3)

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