JP5429042B2 - Hydrophilic film-forming coating solution and hydrophilic film using the same - Google Patents

Description

  The present invention relates to a coating liquid for forming a hydrophilic film and a hydrophilic film using the same. More specifically, it comprises an aqueous and low-temperature-curable hydrophilic coating-forming coating solution containing a water-soluble cage silsesquioxane and a water-soluble zirconium compound, and a cured product of the coating solution. It is related with the hydrophilic film which is excellent in.

  For various substrates such as a touch panel, a liquid crystal screen, a protective film, glasses, and a window glass, a transparent hard coat is generally used for the purpose of protecting the surface, preventing dirt, reducing the friction coefficient, and improving optical properties. As a material for such a transparent hard coat, a silicone compound and a UV curable organic polymer are generally used. However, these materials are (1) a film having sufficient performance cannot be formed unless fired at a high temperature exceeding 150 ° C., and (2) an organic solvent that is cured at a low temperature. (3) Although it uses a solvent that cures at a low temperature and has little substrate damage, the life of the coating solution itself is short, so it should be prepared as a two- to three-component mixed type and used up immediately after compounding. There are some disadvantages. Therefore, it cannot necessarily be applied to every substrate, and has problems in terms of work safety and environmental protection when spray coating or the like is performed during outdoor construction.

  Many of the above-mentioned transparent hard coats are water-repellent and try to achieve the antifouling function by removing dirt-containing moisture from the surface as water droplets or by preventing contamination from getting wet and spreading. To do. However, such a transparent hard coat does not necessarily have a sufficient water-repellent effect, and the antifouling effect may be lost due to gradually depositing contaminants. It could not be said.

  Further, when such a transparent hard coat is used as a base and an overcoat solution is further applied to the surface, the overcoat solution is repelled when the surface is water-repellent. In particular, it is extremely difficult to overcoat a water-based paint. There has not yet been created a coating liquid that can form a functional film having sufficient performance in terms of transparency and hardness on the substrate surface.

  Therefore, (1) it is low-temperature curable, (2) consists of a solvent solution, preferably an aqueous solution, that is safe and free from substrate damage, and (3) the resulting coating has high hardness and transparency, and is always hydrophilic. (4) There is a need for a coating solution that satisfies all the conditions that the pot life and shelf life are sufficiently long.

  In addition, the following is mentioned as a prior art relevant to this invention.

Japanese Unexamined Patent Publication No. 2000-290588 JP2003-073618

  The present invention has been made in view of the above problems, and provides a hydrophilic coating-forming coating solution that can effectively satisfy the above conditions (1) to (4), and a hydrophilic coating using the same. The purpose is to provide.

As a result of intensive studies, the present inventors have found that the above object can be achieved by the following coating solution for forming a hydrophilic film and a hydrophilic film, and have completed the present invention.
That is, the present invention firstly
Provided is a coating solution for forming a hydrophilic film, comprising 0.01% by mass or more of a water-soluble cage silsesquioxane and 0.01% by mass or more of a water-soluble zirconium compound.
The present invention secondly consists of a cured product of the above coating solution, when the water contact angle is 20 degrees or less and the thickness is 200 nm, the total light transmittance is 85% or more, and the haze ratio is Provide a hydrophilic coating that is 3.5% or less.

  The coating liquid of the present invention can use water, alcohol or a mixture thereof as a solvent, and can form a coating liquid that is safe and free of substrate damage. In addition, the coating liquid of the present invention is cured in a short time even at a low temperature of about 90 ° C., and the resulting film is excellent in transparency and hardness, and has a characteristic that its surface has hydrophilicity. Furthermore, since this film does not contain an organic substance, it does not easily deteriorate even when brought into contact with a paint that generates highly reactive radicals, such as a photocatalyst. Therefore, by sandwiching the hydrophilic coating of the present invention between the substrate and the photocatalytic thin film, the substrate can be protected from deterioration due to the photocatalyst, and therefore the hydrophilic coating is also suitable as a base film for the photocatalytic thin film.

  Hereinafter, the present invention will be described in detail.

  The coating solution for forming a hydrophilic film according to the present invention contains a predetermined amount of a water-soluble cage silsesquioxane and a water-soluble zirconium compound, and these components are usually dissolved in a solvent in the coating solution. It exists in the liquid.

[Water-soluble cage silsesquioxane]
The cage-type silsesquioxane refers to a silsesquioxane in which only a trifunctional siloxane unit (so-called T unit) is formed, and a silicon atom in the structure forms a vertex of a polyhedron. Any cage-type silsesquioxane can be used in the coating solution of the present invention as long as it is water-soluble. The water-soluble cage silsesquioxane is preferably soluble alone as well as in water. The water-soluble cage silsesquioxane may be used alone or in combination of two or more. Examples of the water-soluble cage silsesquioxane include the following structural formula (1):

（式中、Rは独立に水素原子または官能基である。）
で表されるT³ ₈構造を有するカゴ型シルセスキオキサン、下記構造式（２）：

(In the formula, R is independently a hydrogen atom or a functional group.)
A cage-type silsesquioxane having a T ³ ₈ structure represented by the following structural formula (2):

（式中、Rは前記のとおりである）
で表されるT³ ₁₀構造を有するカゴ型シルセスキオキサン、下記構造式（３）：

(Wherein R is as defined above)
A cage-type silsesquioxane having a T ³ ₁₀ structure represented by the following structural formula (3):

（式中、Rは前記のとおりである）
で表されるT³ ₁₂構造を有するカゴ型シルセスキオキサンが挙げられる。これらのうち、上記T³ ₈構造を有するカゴ型シルセスキオキサンが好適に使用できる。

(Wherein R is as defined above)
And cage-type silsesquioxane having a T ³ ₁₂ structure represented by: Of these, the cage silsesquioxane having the T ³ ₈ structure can be preferably used.

R is independently a hydrogen atom or a functional group. R may be the same as or different from each other. R is a functional group, for example, as a hydroxy group or a salt thereof: —O ⁻ M ⁺ (wherein M is a cation, for example, a quaternary ammonium ion such as tetramethylammonium or tetraethylammonium; an ammonium ion; A group represented by an alkali metal ion such as sodium ion); 1,2-propanediol group (—CH ₂ CH (OH) CH ₂ OH); 1,2-propanediol oxypropyl group (—C ₃ H ₆ OCH ₂ CH (OH) CH ₂ OH); cyclohexanediol group (—Cy (OH) ₂ , Cy is a cyclohexane ring, OH is bonded to any position on Cy); cyclohexanediol ethyl group (—C ₂ H ₄ Cy (OH) ₂ , Cy is as described above; a carboxy group or a salt thereof as a group represented by the formula: —COO ⁻ M ⁺ (wherein M is as described above); a sulfo group as (-SO ₃ H), or a salt thereof formula: -SO ₃ ^- M ⁺ (wherein, M is the . A cage) a group represented by; phosphono group _{(-P (OH) 2 O)} , or Formula :-P salt thereof _{^{(OH) 2 O - M +}} ( wherein, M is as the Group); an alkylol group such as a methylol group (—CH ₂ OH), an ethylol group (—CH ₂ CH ₂ OH); a polyether group (for example, the formula: — (OR ¹ ) _n —OR ² Wherein R ¹ is an alkylene group such as an ethylene group (—CH ₂ CH ₂ —), and R ² is a hydrogen atom or an alkyl group such as a methyl group, a formula: — ( R ¹ O) _n -R ² (wherein R ¹ and R ² are as defined above, etc.); mercapto group; mercaptopropyl group (—CH ₂ CH ₂ CH ₂ SH); amino Group: aminoethyl group (—CH ₂ CH ₂ NH ₂ ); substituted aminopropyl group (—CH ₂ CH ₂ CH ₂ N ⁺ H _x R ³ _3-x A ⁻ ; x is an integer of 1 to ³ , R ³ is Alkyl groups such as methyl, ethyl, propyl and butyl; One); 2-aminoethyl-3-aminopropyl group _{(-C 3 H 6 NHC 2 H} 4 NH 2); aminophenyl group (-PhNH _2, however, Ph is phenyl group); N-phenyl-aminopropyl group ( -CH ₂ CH ₂ CH ₂ NHPh, Ph is as described above); glycidyl group; glycidyloxypropyl group (-C ₃ H ₆ OG, where G is glycidyl group); alicyclic epoxy group such as epoxycyclohexyl group; A group represented by the formula: -C ₂ H ₄ -E or the formula: -CH ₂ -E (wherein E is an alicyclic epoxy group such as an epoxycyclohexyl group); a propylamic acid group (-C ₃ H ₆ NHCOCHCHCO (OH)); trifluoropropyl group (—CH ₂ CH ₂ CF ₃ ); chloropropyl group (—C ₃ H ₆ Cl); chlorophenyl group (—PhCl, where Ph is a phenyl group); chlorophenylethyl group ( -C ₂ H ₄ PhCl, however, Ph is phenyl group); chlorobenzyl group (-BnCl, however, Bn is a benzyl group); click B benzyl ethyl group (-C ₂ H ₄ BnCl, however, Bn is a benzyl group); maleimide propyl _{(-C 3 H 6 -N (C} 1 OCHCHC 2 O), however, N of (C ¹ OCHCHC ² O) In the moiety, C ¹ and C ² carbon atoms are bonded to the same N atom to form a cyclic maleimide); acryloyloxypropyl group (—C ₃ H ₆ OCOCHCH ₂ ); methacryloyloxypropyl group (—C ₃ H ₆ OCOC (CH ₃ ) CH ₂ ); alkyl group such as methyl group and ethyl group; aromatic group such as phenyl group and phenylethyl group (-C ₂ H ₄ Ph, where Ph is phenyl group); ureido group (—NHCONH ₂ ); ureidopropyl group (—C ₃ H ₆ NHCONH ₂ ); cyano group (—CN), cyanopropyl group (—C ₃ H ₆ CN), isocyanate propyl group (—C ₃ H ₆ NCO), etc. The cage silsesquioxane represented by any one of the structural formulas (1) to (3), which is a group of

  A commercially available product can be used as the water-soluble cage silsesquioxane. As a commercial item, the product made from Hybrid Plastics, such as MS0860 (brand name), is mentioned, for example.

  The content of the water-soluble cage silsesquioxane is usually 0.01% by mass or more, preferably 0.1 to 90% by mass, more preferably 0.1 to 50% by mass in the coating liquid of the present invention. .

[Water-soluble zirconium compound]
The water-soluble zirconium compound includes a zirconium oxide compound and a precursor thereof. A water-soluble zirconium compound may be used individually by 1 type, or may use 2 or more types together. Examples of the water-soluble zirconium compound include zirconium oxide, zirconium hydroxide, zirconium oxychloride (zirconium oxychloride), zirconium sulfate, zirconium nitrate, zirconium hydrochloride, zirconium acetate, zirconium formate, zirconium carbonate, basic zirconium carbonate, zirconium carbonate. Ammonium, potassium zirconium carbonate, zirconium octylate, zirconium tetranormal propoxide, zirconium tetraacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis (ethylacetoacetate), zirconium tetraacetylacetonate, zirconium These hydrolysates or partial hydrolysates such as tributoxy monostearate And the like. A commercial item can be used as a water-soluble zirconium compound.

  Content of a water-soluble zirconium compound is 0.01 mass% or more normally in the coating liquid of this invention, Preferably it is 0.01-80 mass%, More preferably, it is 0.01-60 mass%. Further, the content of the water-soluble zirconium compound is preferably 0.01 to 200% by mass, more preferably 0.01 to 70% by mass, and still more preferably 5 to 60% by mass with respect to the water-soluble cage silsesquioxane. is there.

[solvent]
As the solvent for obtaining the coating liquid of the present invention, water is suitable, but alcohols such as methanol, ethanol and isopropanol, or a mixture of water and alcohol may be used. These alcohols may be used alone or in combination of two or more.

[Coating fluid]
The coating liquid of the present invention can be prepared by adding the above water-soluble cage silsesquioxane and the water-soluble zirconium compound to the above solvent and mixing them. In the coating solution thus prepared, it is presumed that a cage-type silsesquioxane-zirconia complex is formed.

[Substrate]
The substrate to which the hydrophilic film-forming coating solution of the present invention is applied is not particularly limited as long as a hydrophilic film can be formed. Examples of the base material include organic materials and inorganic materials. Examples of inorganic materials include non-metallic inorganic materials and metallic inorganic materials. These can have various shapes according to their purposes and applications.

  Examples of organic materials include vinyl chloride resin, polyethylene, polypropylene, polycarbonate, acrylic resin, polyacetal, fluorine resin, silicone resin, ethylene-vinyl acetate copolymer (EVA), acrylonitrile-butadiene rubber (NBR), polyethylene terephthalate ( PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), ethylene-vinyl alcohol copolymer (EVOH), polyimide resin, polyphenylene sulfide (PPS), polyether imide (PEI), polyether ether imide (PEEI) And synthetic resin materials such as polyetheretherketone (PEEK), melamine resin, phenolic resin, acrylonitrile-butadiene-styrene (ABS) resin; natural, synthetic or semi-synthetic fiber materials and fiber products. These may be commercialized into required shapes and configurations such as films, sheets, other molded products, and laminates.

  Examples of the nonmetallic inorganic material include glass, ceramic, and stone. These may be commercialized in various forms such as tiles, glass, mirrors, and design materials.

  Examples of the metal inorganic material include cast iron, steel material, iron, iron alloy, aluminum, aluminum alloy, nickel, nickel alloy, zinc die cast, etc., and these may be plated or organic materials may be used. It may be applied. Moreover, the metal plating film provided on the surface of nonmetallic inorganic material or organic material may be sufficient.

[Hydrophilic coating]
The hydrophilic coating of the present invention comprises a cured product of the above coating solution, has a water contact angle of 20 degrees or less, and a thickness of 200 nm, has a total light transmittance of 85% or more, a haze ratio Is a hydrophilic film having a content of 3.5% or less. As a method for forming the hydrophilic film of the present invention, for example,
The coating liquid of the present invention is applied to the surface of the substrate to form a coating film,
The method of drying and hardening the obtained coating film at the temperature of 50-200 degreeC is mentioned.

  Any conventionally known method can be used to apply the coating solution to the substrate. Specifically, the substrate is coated using a dip coating method, spin coating method, spray coating method, brush coating method, impregnation method, roll method, wire bar method, die coating method, gravure printing method, ink jet method, etc. Can be formed on top.

  In order to dry and cure the coating film on the substrate, it is preferable to heat-treat for 1 to 120 minutes in a temperature range of 50 to 200 ° C., particularly in a temperature range of 60 to 110 ° C. for 5 to 60 minutes. Is preferred.

  The thickness of the hydrophilic film to be formed is preferably in the range of 1 to 500 nm, particularly preferably in the range of 50 to 300 nm. If the hydrophilic coating is too thin, the strength may be low, and if it is too thick, cracks may occur.

  The hydrophilic coating film of the present invention preferably has a water contact angle of 20 degrees or less (0 to 20 degrees) at room temperature, and preferably 0 to 10 degrees. When the water contact angle exceeds 20 degrees, the antifouling property of the hydrophilic coating and the recoatability with respect to the aqueous overcoat solution may be deteriorated. The water contact angle can be measured using a contact angle meter.

  Further, the hydrophilic coating of the present invention preferably has a total light transmittance of 85% or more (85 to 100%), and a haze ratio of preferably 3.5% or less (0 to 3.5%), more preferably 0. ~ 2.0%. When the total light transmittance is less than 85%, or when the haze ratio exceeds 3.5%, or both, the hydrophilic coating may deteriorate in transparency and impair the appearance. In addition, light transmittance and a haze rate can be measured using a haze meter.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited by the following examples.

[Examples 1 and 2 and Comparative Examples 1 to 5]
An Si component, a Zr component, and a Ti component having the composition shown in Table 1 were blended to prepare an aqueous solution or a methyl ethyl ketone (hereinafter abbreviated as MEK) solution having a total solid content concentration of 1.50% by mass and used as a coating solution.
(Si component)
・ POSS
As water-soluble cage silsesquioxane, MS0860 (trade name, tetramethylammonium salt of octaanion cage silsesquioxane having T ³ ₈ structure, ie, R = —O ⁻ N ⁺ (CH ₃ ) ₄ , a cage-type silsesquioxane having a T ³ ₈ structure represented by the above structural formula (1), manufactured by Hybrid Plastics, was used. Hereinafter, this is expressed as POSS (Polyhedral Oligomeric Silsesquioxane).
・ KR-400
KR-400 (trade name, one-part curable silicone resin, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the water-repellent silicone coating agent.
・ Snowtex S
As a solid silica sol-based binder, Snowtex S (trade name, colloidal silica having a particle diameter of 8 to 11 nm, manufactured by Nissan Chemical Co., Ltd.) was used.
(Zr component)
・ AC-7
As an aqueous solution of the water-soluble zirconium compound, Zircosol AC-7 (trade name, zirconium ammonium carbonate aqueous solution, solid content concentration: 13% by mass, manufactured by Daiichi Rare Elemental Science Co., Ltd.) was used.
(Ti component)
PTA sol Sagan Coat PTA sol (trade name, peroxotitanic acid aqueous solution, solid content concentration 1.70% by mass, manufactured by Sakai Corporation) was used.

[Evaluation method of film]
Using the coating liquids prepared in the above Examples and Comparative Examples, sample films were prepared by the following method, and the performance of the coating was evaluated.
-Preparation of sample film A PET (polyethylene terephthalate) film (thickness 50 μm, A4 size (210 mm × 297 mm)) subjected to corona discharge treatment was used as a substrate. The coating solution was applied to one side of the PET film and heated and dried at 90 ° C. for 10 minutes to prepare a sample film comprising the PET film and a coating having a thickness of about 200 nm formed on the one side.
・ Surface tension (static or dynamic)
In order to evaluate the static surface tension, the water contact angle of the coating was measured at room temperature using a contact angle meter CA-A (product name, manufactured by Kyowa Interface Science).
On the other hand, in order to evaluate the dynamic surface tension, the wetting tension of the coating was measured as follows. That is, at room temperature, a wet film test mixture No. 22.6 to No. 73.0 (manufactured by Wako Pure Chemical Industries, Ltd.) was applied to the coating surface of the sample film with a cotton swab to form a liquid film. It was confirmed whether it was held without being played for 10 seconds. The maximum value of the wet tension corresponding to the liquid mixture for wet tension test in which the liquid film was held was taken as the wet tension (mN / m) of the film. The results are shown in Table 1.
-1 kg load rubbing test A Kim wipe was placed on the coating in the sample film, a 1 kg load was applied to the Kim wipe, the coating was rubbed 10 times, and the presence or absence of scratches on the coating surface was visually confirmed. The results are shown in Table 1.
-Pencil hardness The pencil hardness of the film was measured using a scratch hardness (pencil method) tester (manufactured by Cortec Co., Ltd.) in accordance with JIS K 5600-5-4. The results are shown in Table 1.
・ Appearance (Hue)
The appearance (hue) of the coating was visually confirmed. The results are shown in Table 1.
-Thickness The thickness of the coating was measured using a thin film measuring apparatus F-20 (product name, manufactured by FILMETRICS) and a scanning electron microscope S-3400NX (product name, manufactured by Hitachi High-Technologies). That is, first, it was confirmed that the thickness of the coating was uniform as a whole with the above-mentioned electron microscope, the rough thickness was determined, and then the accurate thickness was determined with the above-mentioned thin film measuring apparatus. The results are shown in Table 1.
Optical characteristics The total light transmittance and haze ratio of the coating were measured using a digital haze meter NDH-20D (manufactured by Nippon Denshoku Industries Co., Ltd.). The results are shown in Table 1.
-Recoatability test To evaluate the wettability of the coating film with water-based paint, Sagancoat TPX85 (trade name, aqueous photocatalyst coating solution, manufactured by Sakai Corporation) was applied to the coating film surface in the sample film by the bar coating method. The uniformity of the formed coating film was evaluated. The evaluation criteria are as follows. The results are shown in Table 1.
○ (Uniform): Unevenness is not confirmed in the coating film by visual inspection.
X (non-uniformity): Unevenness can be visually confirmed in the coating film, or the aqueous photocatalyst coating solution is completely repelled and cannot be applied to the coating film.

  From the results in Table 1, the properties of the coating liquid and the coating obtained in Examples 1 and 2 were the best. That is, the coating solution was aqueous, and the coating film was excellent in hardness and transparency, and was hydrophilic. From Comparative Example 1, the film obtained using a peroxotitanic acid aqueous solution instead of the water-soluble zirconium compound was inferior in hardness. From Comparative Example 2, the film obtained by using the water-soluble zirconium compound alone without using the water-soluble cage-type silsesquioxane increases the amount of reflected light due to the high refractive index considered to be due to zirconia, and the total light The transmittance and haze ratio were adversely affected (difficult optical properties). From Comparative Example 3, a film obtained by using a peroxotitanic acid aqueous solution alone without using a water-soluble cage silsesquioxane or a water-soluble zirconium compound was inferior in hardness and recoatability. From Comparative Example 4, a general silicone coating agent could not be dissolved in water, and the wetness of the obtained film was not high (the wettability was difficult). From Comparative Example 5, although the film obtained using the colloidal silica-based binder had good wettability, it was remarkably inferior in hardness after low-temperature curing (hardness was difficult).

Claims (8)

(A) Water-soluble cage silsesquioxane 0.01% by mass or more,
(B) Water-soluble zirconium compound 0.01% by mass or more, and (c) (c1) water and (c2) a water-based coating solution for forming a hydrophilic film, comprising a solvent selected from a mixture of water and alcohol. The aqueous coating liquid according to claim 1, wherein the water-soluble cage silsesquioxane has a T ³ ₈ structure.   The aqueous coating solution according to claim 1 or 2, comprising 0.01 to 90% by mass of the water-soluble cage silsesquioxane, 0.01 to 80% by mass of the water-soluble zirconium compound, and the remaining amount of solvent.   The aqueous solvent according to claim 1, wherein the solvent is water. When the water contact angle is 20 degrees or less and the thickness is 200 nm, the total light transmittance is 85% or more, comprising a cured product of the aqueous coating liquid according to any one of claims 1 to 4. A hydrophilic film having a haze ratio of 3.5% or less. The hydrophilic coating according to claim 5, wherein the cured product is formed on a PET film. The hydrophilic coating according to claim 5 or 6, wherein the cured product is dried and cured at a temperature of 50 to 200 degrees. The hydrophilic film according to any one of claims 5 to 7 , which is a base film of a photocatalytic thin film.