JP7200937B2 - Composition for forming hydrophilic coating film, and hydrophilic coating film using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composition for forming a hydrophilic coating film having a hydrophilizing surface and an antifogging effect, and a hydrophilic coating film using the composition.

Antifog properties, antistatic properties, antifouling properties, biocompatibility, and the like are known as surface properties required for substrates. These surface properties are generally achieved by imparting hydrophilicity to the surface of the base material, such as by coating the surface with a hydrophilic film.
Examples of polymers that can impart hydrophilicity to substrates include polymers of phosphoryl group-containing methacrylic acid esters (see Patent Document 1), and compounds having a betaine group that has a very strong interaction with water, which are covalently bonded to inorganic substrates. is known (see Patent Document 2).

However, these materials have a problem that their surface properties such as hydrophilicity and anti-fog properties deteriorate gradually or rapidly when stored under high-temperature and high-humidity conditions.

Japanese Patent Laid-Open No. 6-313009

The present invention has been made in view of these points, and an object of the present invention is to form a hydrophilic coating film that does not deteriorate in surface properties such as hydrophilicity and antifogging even when stored under high temperature and high humidity conditions. The object of the present invention is to provide a composition for use in a medical device and a hydrophilic coating film obtained therefrom.

Thus, the present invention has the following gists.
[1] A composition for forming a hydrophilic coating film, containing a siloxane monomer having a betaine group having a positive (+) charge on the nitrogen atom in the nitrogen-containing heterocyclic structure, and water or an organic solvent.
[2] A method for forming a hydrophilic coating, comprising coating a substrate with the composition for forming a hydrophilic coating film described above to form a coating film, drying and baking the coating film to obtain a coating film.
[3] A hydrophilic coating film obtained from the composition for forming a hydrophilic coating film described above.

According to the present invention, it is possible to provide a composition for forming a hydrophilic coating film whose hydrophilicity and antifogging properties do not deteriorate even when stored under high-temperature and high-humidity conditions, and a hydrophilic coating film obtained therefrom.
The hydrophilic coating film obtained from the composition for forming a hydrophilic coating film of the present invention can be used as a water droplet adhesion prevention film for glasses, lenses of cameras and the like, windows of buildings, cars, etc., anti-fogging films, and the like. can.

The hydrophilic coating film-forming composition of the present invention comprises a siloxane monomer having a betaine group having a positive (+) charge on the nitrogen atom in the nitrogen-containing heterocyclic structure (hereinafter also referred to as a specific siloxane monomer), water Alternatively, it is characterized by containing an organic solvent.

<Specific siloxane monomer>
The composition for forming a hydrophilic coating film of the present invention has a siloxane monomer having a positively charged betaine group on the nitrogen atom in the nitrogen-containing heterocyclic ring structure.
Betaine is a compound that has a positive charge and a negative charge at positions that are not adjacent to each other in the same molecule, and does not have a dissociable hydrogen atom attached to the positively charged atom, so the molecule as a whole has no charge. be.

The positive charge of the betaine group contained in the specific siloxane monomer resides on the nitrogen atom on the nitrogen-containing heterocycle. Examples of nitrogen-containing heterocycles include pyridine, piperidine, imidazole, oxazole, thiazole, pyrazole, imidazoline, pyrazine, benzimidazole, quinoline, isoquinoline, purine, quinoxaline, etc. Among them, pyridine and imidazoline are preferred.

A specific siloxane monomer is represented by the following general formula.

In formula [1] above, R ₁ represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms.
R ₂ is an alkyl group having 1 to 5 carbon atoms, preferably 1 to 4 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, preferably 2 to 4 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms, preferably 2 to 4 carbon atoms. show. Any hydrogen atom of R ₂ may be substituted with an alkyl group having 1 to 5 carbon atoms, a halogen atom such as a fluorine atom, an aromatic ring, or an aliphatic ring. p represents an integer of 1 to 3; q represents an integer of 0 to 2 when p is 1, an integer of 0 to 1 when p is 2, and 0 when p is 3;

L represents a linear or branched alkylene group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, which may have a heteroatom. Any hydrogen atom of the alkylene group may be substituted with an alkyl group having 1 to 5, preferably 1 to 4 carbon atoms, a halogen atom such as a fluorine atom, an aromatic ring, or an aliphatic ring. Among them, a linear or branched alkylene group having 2 to 7 carbon atoms, preferably 2 to 6 carbon atoms is preferable. Here, heteroatom means oxygen, nitrogen, sulfur or phosphorus, with oxygen, nitrogen or sulfur being preferred.

X represents a single bond, -O-, -COO-, -OCO-, -CONR ₃ -, -NR ₄ -CO-, or -NR ₅ =NR ₆ -. R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms.
Y represents a divalent organic group containing a nitrogen-containing heterocycle. Examples include pyridine, piperidine, imidazole, oxazole, thiazole, pyrazole, imidazoline, pyrazine, benzimidazole, quinoline, isoquinoline, purine, quinoxaline, etc. Among them, pyridine or imidazoline is preferred.

M represents a linear or branched alkylene group having 1 to 10 carbon atoms, preferably 1 to 8, and any hydrogen atom of the alkylene group is an alkyl group having 1 to 5 carbon atoms, preferably 1 to 4 Alternatively, it may be substituted with a halogen atom such as a fluorine atom. Among them, a linear or branched alkylene group having 2 to 7 carbon atoms, preferably 2 to 6 carbon atoms is preferable. M is bonded to the nitrogen atom of Y, and one of M and L is bonded to the nitrogen atom of Y to form an N ⁺ portion.
Z represents COO ⁻ , SO ₃ ⁻ , or PO ₄ ⁻ . From the viewpoint of the durability of the resulting coating film, SO ₃ ^- is preferred.

Specific examples of specific siloxane monomers are shown below, but are not limited thereto.

In the formula, Me represents a methyl group and Et represents an ethyl group. Also includes tautomers with respect to the N ⁺ portion.
Among them, the following are preferable as the specific siloxane monomer from the viewpoint of monomer stability and raw material availability.

<Method for producing specific siloxane monomer>
The specific siloxane monomer used in the present invention is, for example, a sultone ring such as 1,3-propanesultone, 1,4-butanesultone and 2,4-butanesultone in a nitrogen-containing heterocyclic structure-containing silicon compound in the case of sulfonic acid termination. It can be produced by reacting compounds.

A carboxylic acid-terminated compound can be obtained by reacting a silicon compound containing a nitrogen-containing heterocyclic structure with a lactone ring compound such as β-propiolactone. A carboxylic acid-terminated compound can also be obtained by a method of adding acrylic acid to a nitrogen-containing heterocyclic structure-containing silicon compound. A carboxylic acid-terminated compound can also be obtained by reacting an alkali metal haloacetate such as potassium monochloroacetate, sodium monochloroacetate, potassium monobromoacetate, or sodium monobromoacetate with a nitrogen-containing heterocyclic structure-containing silicon compound in a non-aqueous solvent. can be done.

Examples of reaction solvents include water, alcohols (methanol, ethanol, 2-propanol, etc.), aprotic polar organic solvents (dimethylformamide, dimethylsulfoxide, dimethylacetamide, N-methylpyrrolidone, etc.), ethers (diethyl ether, diisopropyl ether, tert-butyl methyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, etc.), aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.), aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.), halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.), lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.), nitriles (acetonitrile, propionitrile, butyronitrile, etc.) and the like can be used. These solvents can be appropriately selected in consideration of the easiness of reaction and the like, and can be used singly or in combination of two or more. In some cases, the above solvent can also be used as a solvent that does not contain water by using a suitable dehydrating agent or drying agent.
Preferred solvents include acetonitrile or tetrahydrofuran.

The reaction time is 30 minutes to 180 hours, preferably 2 to 120 hours, particularly preferably 5 to 100 hours.
The silicon compound containing a nitrogen-containing heterocyclic structure, which is a raw material, is commercially available or can be easily obtained by a known method. The reaction temperature is preferably 0°C to the boiling point of each solvent, more preferably 0°C to 120°C, particularly preferably 5°C to 100°C.

When the specific siloxane monomer, which is the reaction product, precipitates in the reaction organic solvent, it can be highly purified by a method such as filtration and drying. When the reaction proceeds in a homogeneous system from beginning to end, the resulting reaction product may be used as it is. However, when the target specific siloxane monomer is solid, the reaction solvent is concentrated and then a poor solvent is added for crystallization or It can be isolated and purified by known methods such as reprecipitation.

<Other ingredients>
The hydrophilic coating film-forming composition of the present invention is selected from the group consisting of specific siloxane monomers, water or organic solvents, metal alkoxides, metal alkoxyligomers, metal alkoxide polymers, inorganic fine particles, leveling agents and surfactants. At least one or more may be contained.

The metal alkoxide is contained in order to enhance the mechanical stability of the formed coat film, and examples of the metal of the metal alkoxide include silicon, titanium, aluminum, tantalum, antimony, bismuth, tin, indium, and zinc. mentioned. Among these, silicon, titanium, or zirconium is preferable from the viewpoint of availability.

Examples of the metal alkoxide include those represented by the following formula (II) or (III).
M ¹ (OR ² )n (II)
In formula (II), R ² represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, or an acetyl group. n represents an integer of 2-5. ^M1 is preferably silicon (Si), titanium (Ti), zirconium (Zr), or aluminum (Al), and particularly preferably silicon (Si) or titanium (Ti). Also, n is preferably 3 or 4.

^R3xM1 (OR2) ⁴ _{-x (} ^III )
In formula (III), M ¹ and R ² are as defined in formula (I) above. R ³ is optionally substituted with a hydrogen atom, a halogen atom, a vinyl group, a styryl group, a phenyl group, a naphthyl group, an acrylic group, a methacrylic group or an aryl group, and may contain a heteroatom. It is a group selected from the group consisting of alkyl groups having 1 to 30 carbon atoms. x is an integer of 1-3. The heteroatoms here are oxygen, nitrogen, sulfur or phosphorus, preferably oxygen, nitrogen or sulfur.

Examples of the metal alkoxide represented by the formula (II) include silicon alkoxides such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetraacetoxysilane, titanium tetraethoxide, titanium tetrapropoxide, Titanium alkoxides such as titanium tetrabutoxide, zirconium tetraalkoxides such as zirconium tetraethoxide, zirconium tetrapropoxide, zirconium tetrabutoxide, aluminum trialkoxide compounds such as aluminum tributoxide, aluminum triisopropoxide, aluminum triethoxide, tantalum Examples include tantalum pentaalkoxides such as pentapropoxide and tantalum pentabutoxide. These can be used alone or in combination of two or more.

When M1 in the above formula ( ^III ) is silicon and R3 is ^a hydrogen atom, examples include trimethoxysilane, triethoxysilane, tripropoxysilane, tributoxysilane and the like. These can be used alone or in combination of two or more.

When M ¹ in formula (III) above is silicon and R ³ is an organic group, for example, methyltrimethoxysilane, methyltripropoxysilane, methyltriacetoxysilane, methyltributoxysilane, methyltripentoxysilane , methyltriamyloxysilane, methyltriphenoxysilane, methyltribenzyloxysilane, methyltriphenethyloxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl)methyltri Methoxysilane, (3,4-epoxycyclohexyl)methyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, β-(3 ,4-epoxycyclohexyl)ethyltripropoxysilane, β-(3,4-epoxycyclohexyl)ethyltributoxysilane, β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, γ-(3,4-epoxycyclohexyl) ) propyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)propyltriethoxysilane, δ-(3,4-epoxycyclohexyl)butyltrimethoxysilane, δ-(3,4-epoxycyclohexyl)butyltriethoxysilane , glycidoxymethyl methyl Dimethoxysilane, glycidoxymethylmethyldiethoxysilane, α-glycidoxyethylmethyldimethoxysilane, α-glycidoxyethylmethyldiethoxysilane, β-glycidoxyethylmethyldimethoxysilane, β-glycidoxyethylethyl Dimethoxysilane, α-glycidoxypropylmethyldimethoxysilane, α-glycidoxypropylmethyldiethoxysilane, β-glycidoxypropylmethyldimethoxysilane, β-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropyl methyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ- glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylvinyldimethoxysilane, γ-glycidoxypropylvinyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, γ-Chloropropyltrimethoxysilane, γ-Chloropropyltriethoxysilane, γ-Chloropropyltriacetoxysilane, 3,3,3-Trifluoropropyltrimethoxysilane, γ-Mercaptopropyltrimethoxysilane, γ-Mercaptopropyltri ethoxysilane, β-cyanoethyltriethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, N-(β-aminoethyl)γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)γ-aminopropyl methyldimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)γ-aminopropyltriethoxysilane, N-(β-aminoethyl)γ-aminopropylmethyldiethoxysilane, dimethyldimethoxysilane, phenyl methyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptomethyldimethoxysilane Ethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltripropoxysilane oran, (R)-N-1-phenylethyl-N'-triethoxysilylpropylurea, (R)-N-1-phenylethyl-N'-trimethoxysilylpropylurea, 3-isocyanatopropyltriethoxysilane, Trifluoropropyltrimethoxysilane, bromopropyltriethoxysilane, diethyldiethoxysilane, diethyldimethoxysilane, trimethylethoxysilane, trimethylmethoxysilane and the like can be mentioned. These can be used alone or in combination of two or more.

The metal alkoxide oligomer and metal alkoxide polymer are contained in order to enhance the mechanical stability of the formed coating film. As these metals, silicon, titanium, aluminum, tantalum, antimony, bismuth, tin, indium, zinc and the like can be used alone or as composite oxide precursors. The metal alkoxide oligomers and metal alkoxide polymers may be commercially available products or may be obtained by conventional methods such as hydrolysis from monomers such as metal alkoxides.

Specific examples of commercially available metal alkoxide oligomers and metal alkoxide polymers include methyl silicate 51, methyl silicate 53A, ethyl silicate 40, ethyl silicate 48, EMS-485, SS-101 manufactured by Colcoat Co., Ltd. Titanoxane oligomers such as titanium-n-butoxide tetramer manufactured by Kanto Kagaku Co., Ltd. can be mentioned. These may be used singly or in combination of two or more.

The above-mentioned leveling agent, surfactant and the like are contained in order to improve coating uniformity, and known ones can be used, and commercially available products are particularly preferable because they are readily available.
As the inorganic fine particles, silica fine particles, alumina fine particles, titania fine particles, magnesium fluoride fine particles and the like are preferable, and colloidal solutions of these inorganic fine particles are particularly preferable. The colloidal solution may be one in which inorganic fine particles are dispersed in a dispersion medium, or may be a commercially available colloidal solution.

By including inorganic fine particles in the composition of the present invention, it becomes possible to impart surface shape and other functions to the formed cured film. The inorganic fine particles preferably have an average particle size of 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm. If the average particle size exceeds 0.2 μm, the transparency of the cured film formed using the prepared coating liquid may be lowered. The average particle size is the 50% volume average particle size (D50).

Water or an organic solvent can be used as a dispersion medium for the inorganic fine particles. The colloid solution is preferably adjusted to have a pH or pKa of preferably 1 to 10, more preferably 2 to 7, from the viewpoint of the stability of the film-forming coating liquid.
Organic solvents used as dispersion media for inorganic fine particles include methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, butanediol, pentanediol, 2-methyl-2,4-pentanediol, diethylene glycol, dipropylene glycol, and ethylene. alcohols such as glycol monopropyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene; amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; ethyl acetate and butyl acetate , γ-butyrolactone and the like; and ethers such as tetrahydrofuran and 1,4-dioxane. Among them, alcohols or ketones are preferable. These organic solvents may be used alone or in combination of two or more as a dispersion medium.

Among other components that may be contained, preferred are metal alkoxides, metal oxide sols, or metal alkoxyligomers in which some of the alkoxy groups may be substituted with other organic groups.
The content of the metal alkoxide, metal oxide sol, or metal alkoxydrigomer in the composition of the present invention is 0.5 to 100 parts by mass, preferably 1 to 60 parts by mass with respect to 100 parts by mass of the specific siloxane monomer. Department. Within this range, the hydrophilicity and film stability of the composition of the present invention can be exhibited more effectively.

<Composition for forming a hydrophilic coating film>
The composition for forming a hydrophilic coating film of the present invention is a solution obtained by mixing a specific siloxane monomer and one or more of water or an organic solvent.
Organic solvents include alcohols such as methanol, ethanol, 2-propanol, butanol, diacetone alcohol and trifluoroethanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethylene glycol, diethylene glycol, propylene glycol and hexylene. Glycols such as glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene Glycol ethers such as glycol monomethyl ether and propylene glycol monobutyl ether, esters such as methyl acetate, ethyl acetate and ethyl lactate, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide , γ-butyrolactone, dimethylsulfoxide, tetramethylurea, hexamethylphosphotriamide, m-cresol and the like.
Among them, organic solvents include alcohols such as methanol, ethanol, 2-propanol and trifluoroethanol; glycols such as ethylene glycol, propylene glycol and hexylene glycol; cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, etc. Glycol ethers or N-methyl-2-pyrrolidone are preferred.

The specific siloxane monomer contained in the solution may be hydrolyzed. Acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, oxalic acid, and maleic acid; alkalis such as ammonia, methylamine, ethylamine, ethanolamine, and triethylamine; or metal salts such as hydrochloric acid, sulfuric acid, and nitric acid for hydrolysis of specific siloxane monomers. You may use catalysts, such as.
When hydrolyzing, the reaction temperature is preferably 0°C to boiling point, more preferably 0°C to 120°C, and particularly preferably 5°C to 80°C. The reaction time is preferably 10 minutes to 80 hours, more preferably 30 minutes to 50 hours, particularly preferably 30 minutes to 2 hours.

In the present invention, the solution obtained by the above method may be directly used as the coating composition, or if necessary, the solution obtained by the above method may be concentrated or diluted by adding a solvent. or other solvents may be substituted.
At that time, the solvent used may be the same solvent as used for dissolution, or may be another solvent. This solvent is not particularly limited as long as the silicon compound is uniformly dissolved therein, and one type or a plurality of types can be arbitrarily selected and used.
The content of the specific siloxane monomer in the composition of the present invention is preferably 0.005 to 15% by mass, more preferably 0.01 to 12% by mass in terms of SiO ₂ solid content. Within such a concentration range, it is easy to obtain a desired film thickness with a single application, and it is easy to obtain a sufficient pot life of the solution.

<Film formation>
The composition for forming a hydrophilic coating film of the present invention can be used as a hydrophilic coating film by applying a known coating method to form a coating film on a substrate. Examples of coating methods include dip coating, spin coating, spray coating, flow coating, brush coating, bar coating, gravure coating, roll transfer, blade coating, air knife coating, and slit coating. printing method, screen printing method, inkjet method, flexographic printing method, and the like are used. Among these, the spin coating method, slit coating method, blade coating method, spray coating method and dip coating method are preferable.

<Substrate>
Substrates include glass, plastic {polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, ABS, polycarbonate, polystyrene, epoxy, unsaturated polyester, melamine, diallyl phthalate, polyimide, urethane, nylon, polyethylene, polypropylene, Cycloolefin polymer, polyvinyl chloride, fluororesin (polytetrafluoroethylene resin, polychlorotrifluoroethylene resin, polyvinylidene fluoride resin, polyvinyl fluoride resin, perfluoroalkoxy fluororesin, ethylene tetrafluoride/propylene hexafluoride copolymer coalesced resin, ethylene/tetrafluoroethylene copolymer resin, ethylene/chlorotrifluoroethylene copolymer resin, etc.), polybutadiene, polyisoprene, SBR, nitrile rubber, EPM, EPDM, epichlorohydrin rubber, neoprene rubber, porsulfide, butyl rubber, etc.}, metals (iron, aluminum, stainless steel, titanium, copper, brass, alloys thereof, etc.), cellulose, cellulose derivatives, cellulose analogues (chitin, chitosan, porphyran, etc.) or natural fibers (silk, cotton, etc.) Substrates such as, sheets, films, surface hydrophilization of fibers, and the like.

In addition, if necessary, in order to improve the adhesiveness to the substrate, etc., the substrate is pretreated with a primer, vacuum plasma, atmospheric pressure plasma, corona discharge treatment, flame treatment, Itro treatment, ultraviolet irradiation, ozone treatment, etc. surface activation treatment (method for increasing the surface energy of the base material surface) may be performed.

<Drying>
The hydrophilic coating film of the present invention is obtained by drying and baking the coating film of the composition for forming a hydrophilic coating film formed on the substrate. The temperature of the drying step is preferably in the range of room temperature to 150°C, more preferably in the range of 40 to 120°C. The time is preferably about 30 seconds to 10 minutes, more preferably about 1 to 8 minutes. As a drying method, it is preferable to use a hot plate, a hot air circulation oven, or the like.

<Firing>
Considering the heat resistance of the base material and the environment, the baking step is preferably carried out at a temperature of 80°C to 300°C, more preferably 100°C to 250°C. The time is preferably 5 minutes or longer, more preferably 15 minutes or longer. As the baking method, it is preferable to use a hot plate, a thermal circulation oven, an infrared oven, or the like.

The thickness of the coating obtained by the above method can be selected according to need. The thickness of the coating is preferably 3 to 150 nm because the stability of the hydrophilic coating film can be easily obtained. More preferably, it is 5 to 120 nm.

EXAMPLES The present invention will be described in more detail below according to examples, but the present invention is not limited to these.
The abbreviations used below are as follows.
DHIMES: triethoxy-3-(2-imidazolin-1-yl)propylsilane p-PyTES: 2-(4-pyridylethyl)triethoxysilane DMAPS: 3-(N,N-dimethylaminopropyl)trimethoxysilane MTES: Methyltriethoxysilane TFE: Trifluoroethanol

The products in the synthesis examples below were identified by 1H-NMR analysis. Analysis conditions are as follows.
Apparatus: Varian NMR System 400 NB (400 MHz)
Measurement solvent: CDCl3, DMSO-d6,
Reference substance: tetramethylsilane (TMS) (δ0.0 ppm for 1H)

<Synthesis Example 1: Synthesis of A-1>

Acetonitrile (398.9 g) and DHIMES (199.5 g, 727 mmol) were charged into a reactor, and then 1,3-propanesultone dissolved in acetonitrile (299.3 g) was placed under nitrogen atmosphere and ice cooling conditions. (97.7 g) was added dropwise using a dropping funnel.
After dropping, acetonitrile (99.8 g) was poured to flush the residue remaining on the dropping funnel, and the reaction temperature was raised to room temperature and reacted for 18 hours. After completion of the reaction, concentration was performed under reduced pressure to adjust the total internal weight of the reaction vessel to 459 g. Tetrahydrofuran (1596 g) was added to precipitate crystals, which were filtered and dried to obtain 244 g of A-1 (property: white crystals). 0 g was obtained (yield: 85%).
¹ H-NMR (400 MHz) in CDCl ₃ : 0.57-0.61 ppm (m, 2H), 1.23 ppm (t, J = 7.2 Hz, 9H), 1.69-1.76 ppm (m, 2H ), 2.14-2.21 ppm (m, 2H), 2.90 ppm (t, J = 7.2 Hz, 2H), 3.57 ppm (t, J = 7.2 Hz, 2H), 3.78-3. 85 ppm (m, 8H), 3.93-3.99 ppm (m, 4H), 8.82 ppm (s, 1H)

<Synthesis Example 2: Synthesis of A-2>
40.5 g of A-2 (property: red crystals) was obtained (yield: 74%) in the same manner as in Synthesis Example 1, except that p-PyTES was used as the siloxane monomer.

<Synthesis Example 3: Synthesis of A-3>
49.4 g of A-3 (property: white crystals) was obtained (yield: 82%) by carrying out in the same manner as in Synthesis Example 1 except that DMAPS was used as the siloxane monomer.

<Synthesis Example 4: Synthesis of A-4>
DHIMES (20.0 g, 72.9 mmol) was charged in acetonitrile (30.1 g), and 1,4-butanesultone (11.0 g) was added under nitrogen atmosphere at room temperature. Subsequently, the reaction temperature was set to 45° C. and the reaction was carried out for about 2 days to eliminate the raw material. After completion of the reaction, the solvent was removed by concentration under reduced pressure, and ethyl acetate (20.0 g) and hexane (20.0 g) were added to prepare a suspension solution. The suspension was allowed to stand overnight in a freezer at −25° C. to precipitate crystals, and the crystals were recovered by filtering under a nitrogen atmosphere. The obtained crystals were slurry-washed with hexane (50.0 g), filtered and dried to obtain 20.2 g of A-4 (property: pale yellow crystals) (yield: 67%).

<Synthesis Example 5: Synthesis of A-5>
Triethoxy-3-(2-imidazolin-1-yl)propylsilane (20.0 g, 72.9 mmol) was charged in acetonitrile (40.0 g), and 2,4-butanesultone (10. 4g) was added. Subsequently, the reaction temperature was set to room temperature, and the reaction was allowed to proceed for about one day to eliminate the raw materials. After completion of the reaction, the solvent was removed by concentrating under reduced pressure. The concentrated solution was then diluted with ethyl acetate (80.0 g) and hexane (80.0 g) was added, resulting in a suspension solution. The viscous substance was solidified in a freezer at -25°C, and the supernatant was removed. Ethyl acetate (70.0 g) and hexane (70.0 g) were added again to prepare a suspension, which was again allowed to stand in a freezer at -25°C to precipitate crystals. 28.2 g of A-5 (property: white crystals) was obtained by filtering under a nitrogen atmosphere, washing with hexane, and drying (yield: 94%).

<Preparation Example 1>
39.7 g of A-1 and 36.4 g of TFE were added to a 200 mL flask and stirred to dissolve A-1. A mixture of 0.3 g of oxalic acid, 5.4 g of water and 18.2 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain solution AA.
In a 500 mL flask, 2.5 g of solution AA and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain solution (K1).

<Preparation Example 2>
39.1 g of A-2 and 36.7 g of TFE were added to a 200 mL flask and stirred to dissolve A-2. A mixture of 0.3 g of oxalic acid, 5.4 g of water and 18.4 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain solution AB.
In a 500 mL flask, 2.5 g of solution AB and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain solution (K2).

<Preparation Example 3>
27.8 g of A-1, 5.3 g of MTES and 40.8 g of TFE were added to a 200 mL flask and stirred to dissolve A-1 and MTES. A mixture of 0.3 g of oxalic acid, 5.4 g of water and 20.4 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain solution AC.
In a 500 mL flask, 2.5 g of solution AC and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain solution (K3).

<Preparation Example 4>
32.9 g of A-3 and 40.9 g of TFE were added to a 200 mL flask and stirred to dissolve A-3. A mixture of 0.3 g of oxalic acid, 5.4 g of water, and 20.5 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain solution AD.
In a 500 mL flask, 2.5 g of the solution AD and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain a solution (K4).

<Preparation Example 5>
16.4 g of A-4 and 14.2 g of TFE were added to a 100 mL flask and stirred to dissolve A-3. A mixture of 0.1 g of oxalic acid, 2.2 g of water and 7.1 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain solution AE.
In a 500 mL flask, 2.5 g of the solution AE and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain a solution (K5).

<Preparation Example 6>
16.4 g of A-5 and 14.2 g of TFE were added to a 100 mL flask and stirred to dissolve A-3. A mixture of 0.1 g of oxalic acid, 2.2 g of water and 7.1 g of TFE was added thereto and stirred at room temperature for 2 hours to obtain a solution AF.
In a 500 mL flask, 2.5 g of solution AF and 297.5 g of TFE were mixed and stirred at room temperature for 30 minutes to obtain solution (K6).

<Film forming method>
The solutions K1 to K6 obtained in Preparation Examples 1 to 6 above were filtered under pressure through a membrane filter with a pore size of 0.5 μm, and films were formed on glass substrates by spin coating. The substrate was dried on a hot plate at 70° C. for 3 minutes and then baked in a hot air circulating oven at 200° C. for 30 minutes to obtain a hydrophilic film.
The hydrophilic films (KL1 to KL5) of the solutions K1 to K3 and K5 to K6 obtained in Preparation Examples 1 to 3 and 5 to 6, respectively, were designated as Examples 1 to 5. The hydrophilic film (KM1) of the solution K4 obtained in Preparation Example 4 was used as Comparative Example 1.

The coatings of Examples 1 to 3 and 5 to 6 (KL1 to KL5) and the coating of Comparative Example 1 (KM1) were subjected to the following tests, and the results are shown in Table 1.
<Water contact angle>
Using an automatic contact angle meter CA-Z manufactured by Kyowa Interface Science Co., Ltd., the contact angle was measured when 1 microliter of pure water was dropped.
<High temperature and high humidity test>
Each of the above coatings (KL1 to KL5, KM1) was aged for 3 days in a high-temperature, high-humidity bath oven at a temperature of 60° C. and a relative humidity of 90%. After that, the water contact angle was measured by the above method.

<Water immersion test>
Each of the coatings (KL1 to KL5, KM1) was subjected to ultrasonic cleaning using pure water at room temperature for 5 minutes, and then dried in a hot air circulating oven at 80° C. for 10 minutes. After that, the above high temperature and high humidity test was performed.
<Breath test>
Exhalation was blown to the coating (KL1 to KL5, KM1) that had undergone the water immersion test and the high temperature and high humidity test, and each evaluation was performed, with ○ when the surface of the coating was not clouded, and x when cloudy.

In the coatings of Examples 1 to 5, the hydrophilicity was maintained even after the high-temperature, high-humidity test and the water immersion test, and the results of the breath test showed that the antifogging properties were also maintained. . In the coating of Comparative Example 1, the water immersion test revealed that the hydrophilicity had decreased after 3 days of high temperature and high humidity, and the non-coating surface became cloudy and the anti-fogging property decreased in the breath test as well.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2017-117151 filed on June 14, 2017 are cited here as disclosure of the specification of the present invention. , is to be incorporated.

Claims (11)

Containing a siloxane monomer having a positively charged betaine group on the nitrogen atom in the nitrogen-containing heterocyclic structure, and water or an organic solvent,
A composition for forming a hydrophilic coating film, wherein the siloxane monomer is represented by the following formula [1].

In formula [1], R ₁ represents an alkyl group having 1 to 5 carbon atoms.
R ₂ represents an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having ₂ to 5 carbon atoms; It may be substituted with an alkyl group, a halogen atom, an aromatic ring, or an aliphatic ring. p represents an integer of 1 to 3; q represents an integer of 0 to 2 when p is 1, an integer of 0 to 1 when p is 2, and 0 when p is 3;
L represents a linear or branched alkylene group optionally having a heteroatom having 1 to 20 carbon atoms, and any hydrogen atom of the alkylene group is an alkyl group having 1 to 5 carbon atoms, a halogen atom, It may be substituted with an aromatic ring or an aliphatic ring.
X represents a single bond, -O-, -COO-, -OCO-, -CONR ₃ -, -NR ₄ -CO-, or -NR ₅ =NR ₆ -. R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Y is selected from the group consisting of imidazole, imidazoline, and benzimidazole .
M represents a linear or branched alkylene group having 1 to 10 carbon atoms, and any hydrogen atom of the alkylene group may be substituted with an alkyl group having 1 to 5 carbon atoms or a halogen atom. M is bonded to the nitrogen atom of Y, and one of M and L is bonded to the nitrogen atom of Y to form an N ⁺ portion.
Z represents COO ⁻ , SO ₃ ⁻ , or PO ₄ ⁻ . The composition for forming a hydrophilic coating film according to claim 1 , wherein the siloxane monomer is at least one selected from the following compounds.

The composition for forming a hydrophilic coating film according to claim 1 or 2 , wherein the siloxane monomer is at least one selected from the following compounds.

4. The composition for forming a hydrophilic coating film according to any one of claims 1 to 3 , which contains 0.005 to 12% by mass of the siloxane monomer having a betaine group in terms of SiO ₂ solid content. 5. The composition for forming a hydrophilic coating film according to any one of claims 1 to 4 , further comprising a metal alkoxide, a metal alkoxide oligomer, or a metal alkoxide polymer. 6. The composition for forming a hydrophilic coating film according to any one of claims 1 to 5 , further comprising inorganic fine particles, a leveling agent, or a surfactant. The composition for forming a hydrophilic coating film according to any one of claims 1 to 6 is coated on a substrate to form a coating film, and the coating film is dried and baked to obtain a hydrophilic coating. Coating method. 8. The method for forming a hydrophilic coat according to claim 7 , wherein the coating film is dried at room temperature to 150.degree. C. and baked at 80 to 300.degree. 9. The method for forming a hydrophilic coat according to claim 7 , wherein the thickness of the film after baking is 3 to 150 nm. A hydrophilic coating film obtained from the composition for forming a hydrophilic coating film according to any one of claims 1 to 6 . 11. The hydrophilic coating film according to claim 10 , which is a water droplet adhesion prevention film or an anti-fogging film.