JP2001029876A - Hydrophilic coated material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit a hydrophilic property from the first time of film formation by forming projecting and recessing parts exhibiting capillary phenomena to water on the surface of a coating film. SOLUTION: This coated material has a coating film 2 formed by applying a coating composition with a spin-coater, and the like, on a flat substrate 1. Projecting and recessing parts 5, 6 exhibiting capillary phenomena to water are formed on the surface of the coating film 2. The projecting and recessing parts 5, 6 on the surface of the coating film 2 has a >=5 nm and <=50 nm average surface roughness. The material of the substrate 1 is not limited in particular but usually glass, plastic, and the like, are used. As the glass, sodium glass, and the like, are used and as the plastic, polycarbonate resin, and the like, are used. Thereby, water permeates the projecting and recessing parts formed on the surface of the coating film 2. In the coating film 2 having the projecting and recessing parts on the surface, the more recessive parts through which water can permeate deeply into the coating film 2 are, the smaller contact angle of water the coating film has, therefore, the hydrophilic property of the coating film 2 can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smooth substrate and a hydrophilic coated article formed by applying a coating composition on the substrate to form a coating layer.

[0002]

2. Description of the Related Art As a coated article having a coating film excellent in hydrophilic function, a coated article having a coating film containing a photocatalyst is known (WO96 / 29375, etc.). When a coating film containing a photocatalyst is irradiated with ultraviolet light, it decomposes organic substances repelling water by photocatalysis, thereby reducing the contact angle of water with the coating film surface and making the coating film surface easily wettable with water. The effect of improving the performance is obtained. From the effect of improving the hydrophilicity, an outdoor member is expected to have an anti-fogging effect in which glass, mirrors and the like are hardly fogged by water droplets, and an anti-fouling effect in which attached dirt is washed away by rainwater.

[0003] Since the coating film containing the photocatalyst takes a certain amount of time from the irradiation of ultraviolet rays until the effect of the photocatalysis is exerted, the time until the effect of the photocatalyst is exhibited after film formation is hydrophilic. And the effect is difficult to understand.
In addition, it is difficult to use the photocatalyst indoors or the like exposed to ultraviolet rays because it takes a longer time to exhibit its effect.

[0004] It is also known that a coated article coated with a coating composition containing an alkyl trialkoxysilane, a tetraalkoxysilane, or a mixture thereof as a constituent material has hydrophilicity. However, the coated product is not always obtained with good water wettability, and the coating composition may be unstable and easily gelled, and is stable with the coating composition and has good hydrophilicity. Things are sought.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coated product which exhibits hydrophilicity from the beginning of film formation.

[0006]

According to the first aspect of the present invention,
A smooth substrate, a coated article formed by applying a coating composition on the substrate to form a coating film, and on the surface of the coating film,
It is characterized in that irregularities that exhibit capillary action are formed in water. Thereby, water penetrates into the concave portions formed on the surface of the coating film. In a coating film with irregularities on the surface,
As the concave portion through which water can penetrate deeply by capillary action is provided, the contact angle of water becomes smaller, so that the hydrophilicity of the coating film can be improved.

According to a second aspect of the present invention, in the first aspect, the coating composition comprises a condensate obtained by hydrolyzing at least one of an alkyl trialkoxy silane, a tetraalkoxy silane, and a mixture thereof.
An oxide or oxide sol particles, a curing catalyst, and a solvent, and the unevenness of the coating film is formed by protruding a part of the oxide or oxide sol particles. It is characterized by becoming. Thereby, since a concave portion through which water can penetrate deeply by capillary action can be provided, the contact angle of water of the coating film can be reduced.

According to a third aspect of the present invention, in the second aspect of the present invention, the coating composition comprises a condensate obtained by hydrolyzing at least one of an alkyl trialkoxy silane, a tetraalkoxy silane, and a mixture thereof.
The amount of the oxide or the oxide sol is 50 to 300 parts by weight in terms of solid content with respect to 0 parts by weight. This makes it possible to have a concave portion in which water or a part of the oxide sol protrudes from the surface of the coating film, and into which water can penetrate deeply by capillary action.

According to a fourth aspect of the present invention, in the second or third aspect, the coating composition has a solid content of 2% by weight or less. This makes it possible to have a concave portion in which water or a part of the oxide sol protrudes from the surface of the coating film, and into which water can penetrate deeply by capillary action.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the unevenness on the surface of the coating film has an average roughness Ra of 5 nm or more and 50 nm or less. And Thereby, it is possible to have a concave portion into which water can penetrate deeply by capillary action.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the smooth substrate is
It is characterized by being either glass or plastic. This makes it possible to obtain irregularities exhibiting a capillary phenomenon on the surface of glass or plastic.

[0012]

FIG. 1 is an enlarged view of an essential part schematically showing an example of an embodiment according to the first to sixth aspects.

The above-mentioned coated article is obtained by applying a coating composition on a smooth substrate 1 to form a coating film 2,
The surface of the coating film 2 is formed with irregularities 5 and 6 that exhibit a capillary phenomenon against water.

The substrate 1 is not particularly limited, but examples thereof include glass and plastic. Examples of the above glass include sodium glass, Pyrex glass, quartz glass, and alkali-free glass. As the plastic, for example, a thermosetting or thermoplastic plastic such as a polycarbonate resin, an acrylic resin, an ABS resin, a vinyl chloride resin, an epoxy resin, and a phenol resin, and these plastics are reinforced with inorganic fibers such as nylon fibers. Fiber reinforced plastics (FRP).

The coating film 2 has a concave portion 5 and a convex portion 6 on its surface.
The irregularities 5 and 6 exhibit a capillary phenomenon with respect to water. In the irregularities 5 and 6 where the capillary phenomenon occurs, the contact angle of water on the surface of the coating film can be reduced as the concave portion 5 into which water can penetrate deeply by the capillary phenomenon.

The coating film 2 is formed by applying a coating composition. The coating composition comprises an alkyl trialkoxysilane, a tetraalkoxysilane, or a condensate obtained by hydrolyzing at least one of a mixture thereof, an oxide or oxide sol particles, a curing catalyst, and a solvent. Is exemplified. The irregularities 5 and 6 of the coating film 2 can be formed by projecting a part of the oxide or oxide sol particles 4 from the coat layer 3.

In the above coating composition, alkyl trialkoxy silane, tetraalkoxy silane,
Alternatively, it is desirable that the oxide or oxide sol is 50 to 300 parts by weight in terms of solid content based on 100 parts by weight of a condensate obtained by hydrolyzing at least one of the mixture. If the amount of the oxide or oxide sol is less than 50 parts by weight with respect to 100 parts by weight of the condensate, the number of projecting oxide or oxide sol particles 4 is reduced. Is difficult to obtain, and 30 parts by weight of the oxide or oxide sol is added to 100 parts by weight of the condensate.
If the amount exceeds 0 parts by weight, the particles 4 of the oxide or oxide sol may be easily peeled from the coating film. More preferably, the oxide or oxide sol is 90 to 150 parts by weight based on 100 parts by weight of the condensate.

The alkyltrialkoxysilane is not particularly restricted but includes, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane. And the like. The tetraalkoxysilane is not particularly limited, but examples include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and the like. The mixture may be a mixture of alkyl trialkoxysilane and tetraalkoxysilane. The hydrolysis is
For example, at least one of an alkyl trialkoxy silane, a tetraalkoxy silane, or a mixture thereof,
A hydrolysis catalyst such as water, hydrochloric acid or silica sol is mixed, and the mixture is hydrolyzed.

Examples of the oxide include silica, alumina, zirconia and tin oxide, and examples of the oxide sol include silica sol, alumina sol, zirconia sol and tin oxide sol.

Examples of the curing catalyst include alkyl titanates, tin octylate, dibutyltin dilaurate,
Metal salts of carboxylic acids such as dioctyltin dimaleate; amine salts such as dibutylamine-2-hexoate, dimethylamine acetate, ethanolamine acetate; quaternary ammonium salts of carboxylic acids such as tetramethylammonium acetate; amines such as tetraethylpentamine Class; N-
amine-based silane coupling agents such as β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane; acids such as p-toluenesulfonic acid, phthalic acid, and hydrochloric acid; Aluminum compounds such as aluminum alkoxides and aluminum chelates; alkali catalysts such as potassium hydroxide; titanium compounds such as tetraisopropyl titanate, tetrabutyl titanate, titanium tetraacetylacetonate; halogens such as methyltrichlorosilane, dimethyldichlorosilane, trimethylmonochlorosilane Silane and the like.

Examples of the solvent include methanol,
Lower aliphatic alcohols such as ethanol, isopropanol, n-butanol and isobutanol; ethylene glycol derivatives such as ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; , Toluene, xylene, hexane, heptane, ethyl acetate, butyl acetate, methyl ethyl ketone,
Methyl isobutyl ketone, methyl ethyl ketoxime,
And diacetone alcohol.
One or more species can be used. Among them, alcohols are more preferable from the viewpoint of easy handling.

The coating composition comprises a condensate obtained by hydrolyzing at least one of an alkyl trialkoxysilane, a tetraalkoxysilane, and a mixture thereof;
The oxide or oxide sol particles are stirred and mixed with a stirrer or the like, a curing catalyst is added to the mixture, and the mixture is further diluted with a solvent. This coating composition is desirably prepared and applied so that the solid content is 2% by weight or less. More preferably, the solid content is 0.5% by weight or less. When the solid content exceeds 2% by weight, the particles 4 of the oxide or the oxide sol hardly protrude from the surface of the coating film.

The above coated product is coated with the above coating composition on a smooth substrate 1 by a spin coater or the like.
It is obtained by firing.

In this way, a coating film having irregularities of 5 nm or more in average roughness (center line average roughness Ra) is formed on the surface of the coating film. When the average roughness is less than 5 nm, the manifestation of the capillary phenomenon is insufficient. In addition, the above average roughness 50
A coating film having a thickness exceeding nm has a bad appearance of the coating film and is not suitable for practical use.

[0025]

EXAMPLES In order to confirm the effects of the present invention, a coated article for evaluation was prepared and an evaluation test was conducted. In Examples and Comparative Examples, unless otherwise specified, parts indicate parts by weight and% indicates% by weight. The surface roughness indicates the center line average roughness Ra.

Example 1 A coating composition was prepared as follows. Methyltrimethoxysilane as an alkyl trialkoxysilane, hydrochloric acid as an acid catalyst for hydrolysis, acidic colloidal silica sol as an oxide sol (trade name “OSCAL143, manufactured by Kasei Kasei Kogyo Co., Ltd.)
2 "solid content 30%), N-β-aminoethyl-γ-aminopropyl as a curing catalyst, and methanol as a solvent. 100 parts of methyltrimethoxysilane, 0.01 m
ol / liter of hydrochloric acid (10 parts) and water (14.5 parts) were mixed, and the mixture was stirred with hot water at 60 ° C. for 5 hours and hydrolyzed. Add 300 parts of acidic colloidal silica sol to this condensate
After stirring the mixture with a stirrer, 4 parts of N-β-aminoethyl-γ-aminopropyl was added, and the mixture was further diluted with methanol until the solid content concentration became 0.2%. This solution was aged at room temperature for 3 days to obtain a coating composition.
Observation of the appearance of the coating composition showed no gelation and no abnormal appearance.

The above coating composition is applied to a glass substrate.
It was applied by a spin coater and baked at 100 ° C. for 30 minutes to obtain a coated product having an average surface roughness of 9 nm.

Example 2 Example 1 was repeated except that 500 parts of the acidic colloidal silica sol was blended.
A coating composition was obtained in the same manner as described above. Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to a glass substrate by a spin coater, baked at 100 ° C. for 30 minutes, and had an average surface roughness of 16
nm was obtained.

Example 3 A coating composition was obtained in the same manner as in Example 1, except that 1000 parts of the acidic colloidal silica sol was added. Observation of the appearance of the coating composition revealed no abnormality.
This coating composition was applied to a glass substrate with a spin coater and baked at 100 ° C. for 30 minutes to give an average surface roughness of 3
A 1 nm coated product was obtained.

Example 4 In Example 1, N-β-
Instead of aminoethyl-γ-aminopropyl, except that 2 parts of dibutyltin dilaurate was added as a curing catalyst,
A coating composition was obtained in the same manner as in Example 1. Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to a glass substrate by a spin coater and baked at 100 ° C. for 30 minutes to obtain a coated product having an average surface roughness of 12 nm.

Example 5 A coating composition was obtained in the same manner as in Example 1 except that tetramethoxysilane was used as tetraalkoxysilane instead of methyltrimethoxysilane. Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to a glass substrate by a spin coater, baked at 100 ° C. for 30 minutes, and had an average surface roughness of 13 n.
m were obtained.

Example 6 A coating composition was obtained in the same manner as in Example 1 except that 50 parts of methyltrimethoxysilane and 50 parts of tetramethoxysilane were used instead of methyltrimethoxysilane. Was.
Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to a glass substrate by a spin coater and baked at 100 ° C. for 30 minutes to obtain a coated product having an average surface roughness of 12 nm.

Example 7 In Example 1, alumina sol (alumina sol 52 manufactured by Nissan Chemical Industries, Ltd., trade name) was used instead of the acidic colloidal silica sol as an oxide sol.
(0, solid content 20%) was obtained in the same manner as in Example 1 except that 500 parts of a coating composition was obtained. Observation of the appearance of the coating composition revealed no abnormality.
The coating composition was applied to a glass substrate with a spin coater, baked at 100 ° C. for 30 minutes, and had an average surface roughness of 1
A 9 nm coated product was obtained.

Example 8 A coating composition was obtained in the same manner as in Example 1 except that the solid content was diluted with methanol until the solid content concentration became 0.05%.
Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to a glass substrate with a spin coater and baked at 100 ° C. for 30 minutes to obtain a coated product having an average surface roughness of 18 nm.

Example 9 The coating composition of Example 1 was used. Observation of the appearance of the coating composition revealed no abnormality. This coating composition was applied to an acrylic plate with a spin coater and baked at 100 ° C. for 30 minutes to obtain a coated product having an average surface roughness of 10 nm.

Comparative Example 1 To 100 parts of methyltrimethoxysilane, 4 parts of N-β-aminoethyl-γ-aminopropyl were added, and further diluted with methanol until the solid concentration became 0.2%. did. This solution was aged at room temperature for 3 days to obtain a coating composition.

The above coating composition is applied to a glass substrate.
When applied with a spin coater and baked at 100 ° C. for 30 minutes, the coated product had an average surface roughness of 1 nm or less and no irregularities were observed.

Comparative Example 2 A condensate was prepared in the same manner as in Example 1 using 100 parts of methyltrimethoxysilane, and 300 parts of an acidic colloidal silica sol was added thereto.
After stirring with a stirrer, N-β-aminoethyl-γ-
4 parts of aminopropyl were added, and further diluted with methanol until the solid content concentration became 5%. This solution was aged at room temperature for 3 days to obtain a coating composition.

The above coating composition is applied to a glass substrate.
When applied with a spin coater and baked at 100 ° C. for 30 minutes, the coated product had an average surface roughness of 1 nm or less, and no irregularities were observed.

Comparative Example 3 A condensate was prepared in the same manner as in Example 1 using 100 parts of methyltrimethoxysilane, and 100 parts of an acidic colloidal silica sol was added thereto.
After stirring with a stirrer, N-β-aminoethyl-γ-
4 parts of aminopropyl was added, and further diluted with methanol until the solid content concentration became 0.2%. This solution is
Aged at room temperature for days to obtain a coating composition.

The above coating composition is applied to a glass substrate.
When applied with a spin coater and baked at 100 ° C. for 30 minutes, the coated product had an average surface roughness of 1 nm or less and no irregularities were observed.

(Evaluation) The contact angle of water and the adhesion of the coating film were evaluated.

The contact angle of water was measured immediately after preparation of the coating film. The measurement of the contact angle was performed by dropping 0.2 cc of distilled water on the surface of the coating film and then observing it with a magnifying camera. The smaller the contact angle, the higher the hydrophilicity.

For the adhesion of the coating film, cuts were made in a grid pattern at intervals of 1 mm on the surface of the coating film, a cellophane tape was applied to the cut, and the film was rapidly peeled off, and the presence or absence of peeling was measured. The measurement was performed at 10 places, and the number of pieces that did not cause peeling was recorded.

As shown in Table 1, it was confirmed from the beginning of the film formation that the contact angle of water was better in each of Examples than in Comparative Examples. In addition, no peeling occurred in any of the adhesion of the coating films, and it was confirmed that a coating film having good adhesion was formed.

[0046]

[Table 1]

[0047]

According to the first aspect of the present invention, the surface of the coating film
Since irregularities that cause capillary action are formed in water, it is possible to obtain a coated product in which a coating film having a small water contact angle is formed from the beginning of film formation.

Further, according to the invention as set forth in any one of claims 2 to 4, in particular, it is possible to obtain unevenness in which oxide or oxide sol partially protrudes on the surface of the coating film. Since water penetrates deeply due to the phenomenon, it is possible to obtain a coated product in which a coating film having a small water contact angle is formed from the beginning of film formation.

Furthermore, the invention according to claim 5 has a concave portion through which water can penetrate deeply by capillary action, so that a coated product having a small contact angle of water from the beginning of film formation can be obtained. be able to.

Further, according to the invention of claim 6, a coated article having a small contact angle of water is formed on the surface of glass or plastic, since irregularities exhibiting a capillary phenomenon can be obtained. Can be obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part schematically showing an example of an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 coating film 4 oxide sol particles 5 concave portion 6 convex portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Meiji Goto, Inventor 1048, Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works, Ltd. F term (reference) 4D075 CA37 DA06 DB13 DB31 EA02 EA05 EA12 EB42 EB56 EC02 4J038 DL031 HA216 JC32 KA04 KA06 KA20 NA06 PC03 PC08

Claims (6)

[Claims] 1. A smooth substrate, a coated product formed by applying a coating composition on the substrate to form a coating film, wherein the surface of the coating film has irregularities which develop a capillary phenomenon against water. A hydrophilic coated product characterized by comprising: 2. The coating composition, comprising a condensate obtained by hydrolyzing at least one of an alkyl trialkoxy silane, a tetraalkoxy silane, and a mixture thereof, oxide or oxide sol particles, a curing catalyst, and a solvent. The hydrophilic coating according to claim 1, wherein the unevenness of the coating film is formed by projecting a part of particles of an oxide or an oxide sol. Goods. 3. The coating composition according to claim 2,
With respect to 100 parts by weight of a condensate obtained by hydrolyzing at least one of alkyl trialkoxysilane, tetraalkoxysilane, or a mixture thereof, the oxide or oxide sol is 50 to 300 parts by weight in terms of solid content. The hydrophilic coated article according to claim 2, wherein 4. The coating composition according to claim 2, wherein the solid content of the coating composition is 2% by weight or less.
A hydrophilic coated article according to any of the above. 5. The unevenness on the surface of the coating film has an average roughness Ra
5 is not less than 5 nm and not more than 50 nm, the hydrophilic coated article according to claim 1. 6. The method according to claim 1, wherein the smooth substrate is one of glass and plastic.
A hydrophilic coated article according to any one of claims 1 to 5.