JP2000144122A - Coating liquid composition and coated film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transparent water super-repellent film and impart a same film composition with a water super-repellency or a hydrophilicity. SOLUTION: This coating liquid composition is composed of a single polycondensate of a trialkoxysilane [R1-SO(OR2)3] (R1 is a >=2C alkyl, alkenyl, aryl or aralkyl group and their various derivatives; R2 is a 1-4C alkyl group) or a polycondensate obtained from the trialkoxysilane or its oligomer and a metal alkoxide or its oligomer. A coating liquid comprising the composition is coated on a base material and heat-treated at 350-600 deg.C to form a water super-repellent coated film, or heat-treated at >600 deg.C to form a hydrophilic coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a vehicle, a ship,
Inner / outer window glass, mirror glass, decorative glass, or various building materials and building materials for aircraft or buildings, etc., and a coating liquid composition for forming a film, and a method for forming a film using the composition It is about.

[0002]

2. Description of the Related Art Recently, in various fields such as window materials for buildings and vehicles, mirrors or industrial substrates, it has been carried out to impart water repellency or hydrophilicity to the surfaces of the substrates, and various types of such materials have been used. Proposals have been made to improve performance.

[0003] In order to further improve the durability and water repellency, fine irregularities are given to each surface of the base material, the underlayer or the water repellent layer, and the surface shape is synergistic with the water repellent film or the hydrophilic film. Many techniques have been proposed for providing unique characteristics such as super-water repellency or hydrophilicity by the effect.

For example, regarding water repellency, Japanese Patent Laid-Open Publication No.
No. 124046, JP-A-4-359031,
JP-A-7-138047, JP-A-9-30974
Japanese Patent Application Laid-Open Nos. 4-120407 and 4-2-2 disclose fine irregularities formed in an underlayer.
JP-A-39633, JP-A-6-16455, JP-A-7-267684, JP-A-10-1333, and the like also disclose that a film is formed with a coating solution containing at least dimethyl silicon alkoxide, and the surface layer has an uneven shape. Many proposals have been made for a water-repellent film having, for example, JP-A-10-259037.

[0005] Further, as for the hydrophilic coating, an application for a coating having irregularities is disclosed in, for example, JP-A-7-164971, JP-A-8-227006 and the like in which fine irregularities are formed on an underlayer. Are known.

[0006]

A method of controlling the hydrophilicity / hydrophobicity of a substrate by applying a coating on the surface of various substrates is expected to have a wide variety of applications such as various window materials and wall surfaces of buildings. Technology. In particular, a film exhibiting a so-called super water repellency having a contact angle of 160 ° or more can greatly improve its properties in a field where a conventional water repellent thin film is used, or has a high possibility of being applied to a completely new field. It has attracted attention. However, conventionally obtained super water-repellent thin films are usually opaque due to surface irregularities, and their application range is limited. In order to solve such a problem, we have attempted to produce a completely transparent thin film that exhibits super water repellency.

The water-repellent film obtained in Japanese Patent Application Laid-Open No. 10-259037 uses bifunctional silicon alkoxide as a raw material, and has poor film-forming properties. Pretreatment was required. Further, a coating liquid composition that can be made super-water-repellent or hydrophilic with the same film composition has not been obtained until now.

[0008]

Means for Solving the Problems The present inventors have proposed that a starting material alkoxide, which is considered to play a very important role in controlling the superhydrophobicity and hydrophilicity of a film, is substituted with a substituent such as a methyl group. And examined the relationship between the type of the substituent and the hydrophilicity / hydrophobicity of the obtained thin film. As a result, it was found that when a specific trialkoxysilane was used, a superhydrophobic film was obtained, and that the superhydrophobicity and hydrophilicity of the thin film could be controlled only by changing the heat treatment temperature.

That is, the present invention relates to a trialkoxysilane (R ¹ -Si (OR ² ) ₃ ) wherein R ^{1 is} an alkyl group having 2 or more carbon atoms, an alkenyl group, an aryl group, or an aralkyl group; R ² represents an alkyl group having 1 to 4 carbon atoms) or a polycondensate obtained from the trialkoxysilane or an oligomer thereof and a metal alkoxide or an oligomer thereof. The present invention relates to a coating liquid composition for a super-water-repellent or hydrophilic film, and a method for forming a film using the composition.

The trialkoxysilane is preferably phenyltrialkoxysilane, propyltrialkoxysilane, or 3,3,3-trifluoropropyltrialkoxysilane.

A coating liquid is applied on a substrate,
When the heat treatment is performed at a temperature of at least 600 ° C., a super water-repellent coating having a contact angle θ with water of 140 ° or more can be obtained.
When a coating solution is applied on a substrate and heat-treated at a temperature exceeding 600 ° C., a hydrophilic film having a contact angle θ with water of 5 ° or less can be obtained. This is probably because the heat treatment at a high temperature decomposes the substituents and reduces the hydrophobicity of the film itself, and the fine irregularities on the surface of the thin film work to lower the contact angle. Similar phenomena were observed in a thin film using phenyltriethoxysilane, and it became clear that such control of super water repellency and hydrophilicity was possible with any alkoxide. As described above, according to the present invention, a thin film whose super water repellency and hydrophilicity can be easily controlled can be produced only by controlling the heat treatment temperature of the coating film.

The surface shape of the silica film obtained by using the coating liquid composition of the present invention is about 100 nm to 400 nm.
It has a so-called fractal-like structure in which even smaller irregularities are formed in irregularities with a pitch of nm.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The coating liquid composition is a trialkoxysilane (R ¹ -Si (OR ² ) ₃ ) (where R ¹ :
R ² represents an alkyl group having 2 or more carbon atoms, an alkenyl group, an aryl group, or an aralkyl group, and various derivatives thereof; R ² represents an alkyl group having 1 to 4 carbon atoms); It is a polycondensate obtained from silane or its oligomer and metal alkoxide or its oligomer.

The alkyl group represented by R ¹ is ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl having 2 to 15 carbon atoms. Or a functional group such as heptadecyl is preferred, and those having a straight or branched chain are not limited. In addition, the thing of a C2-C8 functional group is more preferable. Further, as these derivatives, for example, acetoxymethyl, acetoxyethyl, acetoxypropyl, acryloxypropyl, allylaminopropyl, aminopropyl, bromopropyl, chloropropyl, methacryloxymethyl, methacryloxypropyl, methoxypropyl,
Those containing a functional group such as trifluoroacetoxypropyl or trifluoropropyl can also be used.

The alkenyl group for R ¹ has 2 carbon atoms.
-15, vinyl, propenyl, allyl, butenyl,
Functional groups such as pentenyl, pentenyl, peptenyl, octenyl, nonenyl, decenyl, undecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, and heptadecenyl are preferred, and those having 2 to 8 carbon atoms are more preferred.

As the aryl group for R ¹ , those containing a benzene ring such as tolyl, xylyl, styryl, aminophenyl, chlorophenyl or N-phenylaminopropyl are preferred.

As the aralkyl group for R ¹ , benzyl,
Phenethyl, cinnamyl and the like are preferred.

R ² is methyl, ethyl having 1 to 4 carbon atoms,
Preferred is propyl or butyl.

Examples of the metal alkoxide include, for example, tetramethoxysilane, tetraethoxysilaane, tetra-
n-propoxysilane, tetraisopropoxysilane,
Tetra-n-butoxysilane, tetra-sec-butoxysilane, aluminum-sec-butoxide, titanium isopropoxide, titanium-n-butoxide, zirconium-sec-butoxide, and the like are preferable.

The coating liquid composition of the present invention is preferably used in combination with a single polycondensation compound of phenyltrialkoxysilane, propyltrialkoxysilane or 3,3,3-trifluoropropyltrialkoxysilane, or trialkoxysilane or an oligomer thereof. Polycondensates obtained from metal alkoxides or oligomers thereof are preferred.

Examples of phenyltrialkoxysilane, propyltrialkoxysilane or 3,3,3-trifluoropropyltrialkoxysilane include, for example, phenyltrimethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyl Triethoxysilane, isopropyltrimethoxysilane,
Isopropyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, or 3,3,3
-Trifluoropropyltriethoxysilane and the like.

As the solvent to be used, it is preferable to use one or more of water, alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers, amines, or amides. . Specific examples of alcohols include methanol, ethanol, propyl alcohol, butanol, and hexanol.Glycol derivatives include ethylene glycol,
Examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether. Examples of the hydrocarbons include benzene, kerosene, toluene, and xylene, and examples of the esters include methyl acetate, ethyl acetate, butyl acetate, and methyl acetoacetate and ethyl acetoacetate. Examples of ketones include acetone, methyl ethyl ketone, methyl butyl ketone, and acetylacetone, and examples of ethers include ethyl ether, butyl ether, dioxane, furan, and tetrahydrofuran. Examples of amines include monoethanolamine, diethanolamine, and triethanolamine, and examples of amides include formamide or N, N.
N-dimethylformamide and the like.

These commonly used solvents can be used. However, in view of the properties such as super-water repellency or hydrophilicity of the resulting film and the size of the formed unevenness, water,
Glycol derivatives, especially ethylene glycol, amides, especially high-boiling solvents such as formamide and N, N-dimethylformamide are preferred.

The coating liquid comprising trialkoxysilane was diluted with the above solvent, and an acid catalyst such as hydrochloric acid or nitric acid was used as a catalyst. Further, only the alkoxide raw material was used as a coating liquid without using a diluting solvent. The preparation of the coating liquid to be added and mixed with each of the raw materials is performed, for example, as in Example 1 described later.

Examples of the coating method for forming a film include a dipping method, a spin coating method, a nozzle flow coating method, a spray method, a reverse coating method, a flexo method, a printing method, a flow coating method, and a combination thereof.
Known application means can be adopted.

A silica film formed by forming a film on the substrate with the coating solution and performing heat treatment at, for example, 350 ° C. or more for about 1 to 5 minutes is obtained by measuring the surface layer surface by a measurement method according to JIS B0601. And the average roughness Ra obtained by expanding the center line average roughness to about 15 nm
As described above, the surface area ratio S _R is about 1.3 or more.
When the Ra value is less than 10 nm, it becomes difficult to form a more excellent super-water-repellent or hydrophilic film, and when the Ra value becomes extremely large, properties such as performance, strength, and uniformity of the film deteriorate. When the surface area ratio S _R is less than 1.1, it becomes difficult to form a more excellent super water repellent or hydrophilic film, and preferably the surface area ratio S _R
Is about 1.1 to 1.6, and if it exceeds about 1.6, the strength of the film becomes low.

In order to form a super-water-repellent or hydrophilic coating with a single layer of silica film formed on a substrate, as shown in FIG. 1, the surface is formed into a concavo-convex aggregate and the surface area is increased.
The silica film itself acts as a water-repellent layer or a hydrophilic layer, and makes use of the unevenness on the surface of the surface to exhibit a synergistic effect.If the silica film has super-water-repellency, a more excellent super-water-repellent film is used. When the film itself has hydrophilicity, a better hydrophilic film can be obtained in a more stable state.

Regarding the heat treatment at the time of forming the transparent silica film, it is necessary to perform a heat treatment after the film is formed and before the film is dried. For example, in the case of a super water-repellent film, the heat treatment is performed at about 350 to 600 ° C. About 1 to 5 minutes, preferably about 5 minutes
About 1 to 2 minutes at about 00 to 600 ° C., and about 1 to 5 minutes at a temperature exceeding 600 ° C. for a hydrophilic coating. If the temperature is lower than 350 ° C., the above-mentioned uneven shape is not formed.

The thickness of the transparent silica film is about 4
The thickness is preferably from about 0 nm to about 300 nm. If the thickness is less than 40 nm, the above-mentioned uneven shape is not formed, and if the thickness exceeds 300 nm, the risk of cracks occurring in the film after firing increases. Preferably, the range is about 100 to 200 nm.

Further, as a method for evaluating the obtained silica film, a top surface view of the surface layer was observed at about 35,000 times with a scanning electron microscope (SEM), and a cyclic contact mode atomic force was used. Microscope (CC-AF
It is obtained by allowing the display asking the average roughness Ra value and surface area ratio S _R that the center line average roughness Ra of the film in surface extension by observation and the observation of the surface layer surface with M) (see Example 1 Thing). Further, as one method of evaluating the water repellency or hydrophilic performance, a contact angle meter is used to measure the contact angle θ (゜) of the film with respect to a water droplet (water droplet amount of approximately 10 μl) in the air (about 25 ° C.). Was measured. As a result, in the case of water repellency, the contact angle θ is about 140 ° or more, preferably the contact angle θ is about 150 ° or more and about 170 ° or less, has super water repellency, and in the case of hydrophilicity, the contact angle θ Is about 5
゜ or less, preferably a contact angle θ of about 2 ° or less, and excellent hydrophilicity. The substrate is glass,
The material is not particularly limited as long as it is a heat-resistant material such as metal and ceramic.

[0031]

The present invention will be described below in detail with reference to examples. The coating of each example was evaluated by the following method. Water repellency test / Hydrophilicity test: Measuring instrument-C, Kyowa Interface Science
AX type measurement environment-In the air (25 ° C) Water drop-Pure water (10 µl) Observation of coating shape: Using a scanning electron microscope (FE-SEM, Hitachi S4500), the coating was observed at a magnification of about 35,000 times. Atomic force microscope (AFM, mode (Digital Instrument, Nano Scope)
e-E, 5 μm square scan)), the surface of the surface layer and the cross section of the film were observed with a photograph, and the center line average roughness Ra value and the surface area ratio S _R defined in JIS B 0601 were determined. Measurement of film thickness: DEKTAK (manufactured by Sloan, 303
Others measured in 0) Others: For construction, industrial use, for vehicles such as automobiles, and for ships, such as the presence or absence of defects such as cracks, durability of various types of films, and the effect on optical properties such as changes in visible light transmittance. In addition, items required for various glass articles, including window materials for aircraft, etc., were evaluated.

Example 1 A float glass (soda lime silicate composition) having a size of about 100 mm × 100 mm and a thickness of about 2 mm was used as a substrate, the coating surface was sufficiently polished with cerium oxide, and washed with tap water. After rinsing with ion exchange water, wipe with isopropyl alcohol or acetone,
A glass substrate for coating was used. On the other hand, a coating solution was prepared by the following procedure. First, phenyltriethoxysilane [C ₆ H ₅ Si (OCH ₂ CH ₃ ) ₃ ] is used as the phenyl silicon alkoxide, formamide [HCONH ₂ ] is used as the solvent, and phenyltriethoxysilane: formamide = 1.25: 5
Was added thereto, and 1 ml of 2M hydrochloric acid was added thereto. After stirring for about 30 minutes, the mixture was allowed to stand and separated into two phases, and the alkoxide-rich upper layer liquid was used as a coating solution.
The coating solution was applied onto the previously prepared glass substrate by dip coating, and then heat-treated at about 500 ° C. for about 1 minute while the film was in a wet state to form a silica film. The pulling speed at the time of dip coating was about 2 mm / sec.

As a result, when the obtained coating film of the glass with the transparent silica film was evaluated, the contact angle with water of the coating film was about 165 °, showing super water repellency, and a high contact angle was maintained for a long time. Regarding the shape of the film, the surface and cross section of the surface of the film were photographed with the AFM, and the center line average roughness Ra value and the like defined in JIS B0601 were determined. roughness (center line roughness) is in the range of about 15～17Nm, also, the surface area ratio S _R was about 1.3. In addition, when the surface of the surface layer was observed with a photograph of about 35,000 times in the SEM using the SEM, the surface had an irregular shape of about 200 nm as shown in FIG. It turned out that it has a surface shape similar to a so-called fractal that forms fine irregularities. Further, the visible light transmittance was about 94%, which was higher than the transmittance of the glass substrate alone of 92%. This is because the reflectance was reduced due to the uneven shape of the surface of the transparent silica film. The reflection color tone of the film was neutral.

Example 2 Example 1 was repeated except that n-propyltriethoxysilane [CH ₃ CH ₂ CH ₂ Si (OCH ₂ CH ₃ ) ₃ ] was used as a raw material for silicon alkoxide as a coating solution.
The same as above.

As a result, the contact angle of the coating with water was about 1
It exhibited super water repellency at 60 ° and excellent water repellency, and kept a high contact angle for a relatively long time. Regarding the shape of the coating, the surface roughness (center line roughness) is about 16 to 1
In the range of 7 nm, also the surface area ratio S _R is about 1.3
Met.

Example 3 As a coating solution, 3,3,3-trifluoropropyltriethoxysilane [CF ₃ CH ₂ CH ₂ Si (O
CH ₂ CH ₃ ) ₃ ] was used in the same manner as in Example 1 except that silicon alkoxide was used as a raw material.

As a result, the contact angle of the coating with water was about 1
It exhibited super water repellency at 62 ° and excellent water repellency, and maintained a high contact angle for a relatively long time. Regarding the shape of the coating, the surface roughness (center line roughness) is about 15 to 1
In the range of 7 nm, also the surface area ratio S _R is about 1.3
Met.

Example 4 Using phenyltriethoxysilane as a silicon alkoxide, no solvent and no hydrochloric acid as a hydrolysis catalyst, only an alkoxide raw material was used as a coating solution.
The film formation and heat treatment were the same as in Example 1.

As a result, the contact angle of the coating with water was about 1
It exhibited super water repellency at 65 ° and excellent water repellency, and maintained a high contact angle for a relatively long time. Regarding the shape of the coating, the surface roughness (center line roughness) is about 15 to 1
In the range of 7 nm, also the surface area ratio S _R is about 1.3
Met. Further, when a photograph of the surface layer of the coating film was observed with the SEM, the surface had an uneven shape of about 200 nm, and a fine unevenness was formed in the unevenness. It was found to have a shape. The reflection color tone of the film was neutral.

Example 5 The procedure of Example 1 was repeated, except that the applied film was heat-treated at 650 ° C. in comparison with Example 1.

As a result, when the obtained coating film of the glass with a transparent silica film was evaluated, the coating film showed a hydrophilic property with a contact angle to water of about 1 °, and maintained a low contact angle for a long time.

[0042]

Industrial Applicability The coating liquid composition of the present invention is a coating liquid composition capable of producing a significantly excellent silica film, and the obtained film itself has a film exhibiting super water repellency or hydrophilic performance. It has a unique performance that can be obtained only by changing the heat treatment temperature, which is not present in conventional coating liquid compositions, and is used for windows for architectural, industrial, automotive and other vehicles, ships, aircraft, etc. And various other coating solutions for water-repellent or hydrophilic coatings.

[Brief description of the drawings]

FIG. 1 is an SEM photograph instead of a drawing showing a fine uneven structure on the surface of a coating film of Example 1.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshiyuki Owada, Inventor 2-238-309, Shinsenri-minami-cho, Toyonaka-shi, Osaka (72) Inventor Hiroshi Inaba 1510 Oguchicho, Matsusaka-shi, Mie Central Glass 72) Inventor Keiji Honjo 1510 Oguchi-cho, Matsusaka-shi, Mie Central Glass F-term in Glass Research Laboratories, Inc.

Claims (6)

[Claims] (1) A trialkoxysilane (R ¹ -Si (O
R ² ) ₃ ) (provided that R ¹ represents an alkyl group, alkenyl group, aryl group, or aralkyl group having 2 or more carbon atoms and various derivatives thereof, and R ² represents an alkyl group having 1 to 4 carbon atoms) Or a polycondensate obtained from the trialkoxysilane or an oligomer thereof and a metal alkoxide or an oligomer thereof, the coating liquid composition for a super-water-repellent or hydrophilic film. 2. The composition according to claim 1, wherein the trialkoxysilane is phenyltrialkoxysilane, propyltrialkoxysilane, or 3,3,3-trifluoropropyltrialkoxysilane. 3. A super-water-repellent coating having a contact angle θ of 140 ° or more with water by applying the coating solution according to claim 1 on a substrate and performing heat treatment at 350 to 600 ° C. A method for forming a super water-repellent coating. 4. A hydrophilic coating, wherein the coating liquid according to claim 1 is applied to a substrate and heat-treated at a temperature exceeding 600 ° C. to obtain a hydrophilic coating having a contact angle θ with water of 5 ° or less. Method of forming a functional film. 5. The method according to claim 3, wherein the surface of the film has an uneven shape. Wherein said irregularities, the average surface roughness Ra value by the measurement method of JIS B 0601 is 15nm or more, the surface area ratio S _R is according to claim 5, wherein the coating, characterized in that 1.3 or more Forming method.