JPH10237431A - Member with ultrawater-repellent surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a member of which the surface exhibits an ultrahigh water repellency, can permanently maintain such ultra-high water repellency, and is excellent in prevention of water drop formation, prevention of deposition of water-base dirt, washability with flowing water, resistance to snow acretion, etc., by forming a surface layer contg. pohotocatalyst particles, a silicone, and a water-repellent fluororesin and having a thickness lower than the secondary particle size of the fluororesin on the surface of a substrate. SOLUTION: A surface layer contg. photocatalytic oxide particles, a silicone or amorphous silica, and a water-repellent fluororesin is formed on the surface of a substrate of the member. The thickness of the layer is lower than the secondary particle size of the fluororesin, pref. 0.4μm or lower. Examples of the photocatalytic oxide are anatase titanium oxide, rutile titanium oxide, and zinc oxide. Polytetrafluoroethylene, polychlorotrifluoroethylene, and polyhexafluoropropylene can be suitably used as the fluororesin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member having a surface having a super water repellency of 140.degree. Or more in terms of a contact angle with water and capable of maintaining the super water repellency permanently. More specifically, the present invention relates to a member having a surface having excellent drip-proof property. Further, the present invention relates to a member having a surface having excellent drainage properties. Further, the present invention relates to a member having a surface to which water-based dirt does not easily adhere. In addition, the present invention relates to a member having a surface having excellent running water washability. In addition, the present invention relates to a member having a surface having excellent snow prevention properties.

[0002]

2. Description of the Related Art It is often experienced that windshields, side glasses, door mirrors, fender mirrors, and road mirrors of automobiles suffer from rainfall and splashes on rainy weather, causing a large number of discrete water droplets to adhere to them, resulting in loss of visibility. Is to be done. Further, when water droplets adhere to the transmission line, the shape of the water droplets becomes a downward conical shape, so that the discharge becomes easy and leads to a power transmission loss. Also, in the winter, water drops droop like icicles,
The tip is sharp and the discharge amount is further increased. In addition, the creepage insulation of the insulator is significantly reduced due to the adhesion of water droplets. Also,
In the heat exchanger, the moisture adhering to the fins grows in the form of water droplets and is retained between the fins by capillary action, so that the water droplets become the resistance of the air flowing between the fins, thereby lowering the heat exchange efficiency. In addition, the roof in a snowfall area may be deformed due to the weight of the roof due to the large amount of snow, so that it is necessary to frequently perform heavy snow removal.
Also, in the case of an antenna in a snowfall area, icing snow sometimes causes a communication failure such as a decrease in electric field strength. Further, in the bathtub, water stains easily adhere to the apron portion, which may impair the aesthetic appearance of the bathtub used.

[0003]

The above-mentioned problems caused by the adhesion of water droplets can be solved by forming a flowable surface. According to conventional wisdom, in order to express the above-mentioned dripping properties on the surface,
It has been proposed to coat a substrate surface with a water-repellent paint such as polytetrafluoroethylene (PTFE).
However, in a polytetrafluoroethylene plate, 11
The water repellency of about 0 ° is not sufficient, and the surface is easily charged with static electricity, so that dust or the like easily adheres and the water repellency is hardly maintained. Further, as shown in the examples described later, water droplets are adhered to the surface coated with the water-repellent paint, and when the substrate is inclined, the water droplets do not easily move unless tilted by 60 ° or more, and When moved, the apex of the water droplet moves preferentially and moves like pulling a string, so the water mark remains on the moved part after the water droplet falls, and it does not have sufficient flowability and dripproofness .

The present invention has been made in view of the above circumstances, and has a surface exhibiting a super water repellency of 140 ° or more in terms of a contact angle with water, and the super water repellency can be maintained permanently. An object is to provide a member.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a photocatalytic oxide particle and a silica-based material are provided on a substrate surface.
Having a super water-repellent surface, wherein a surface layer containing a water-repellent fluororesin is formed, and the surface layer has a thickness smaller than a secondary particle diameter of the water-repellent fluororesin. I will provide a. With such a configuration, when the photocatalyst is photoexcited, the organic group bonded to the silicon atom in the silicone molecule is at least partially replaced by a hydroxyl group by the photocatalysis, thereby exhibiting hydrophilicity, Both the part where the silicone is exposed to the outside air and / or the part exhibiting hydrophilicity composed of the part where the photocatalytic oxide particles are exposed, and the part exhibiting the water repellency where the water-repellent fluororesin is exposed to the outside are formed on the surface. A microscopically dispersed structure results. In such a structure, since the hydrophilic surface and the water-repellent surface are microscopically adjacent to each other, the water droplet cannot essentially adapt to the surface. Further, by making the secondary particle diameter of the water-repellent fluororesin larger than the thickness of the surface layer, the water-repellent fluororesin is surely exposed, and the dispersion structure is more reliably realized, and the surface is Macroscopically, it exhibits a high degree of water repellency of 140 ° or more in terms of a contact angle with water. Furthermore, the presence of the photocatalyst maintains the surface of the water-repellent fluororesin in a clean state by the oxidative decomposition action of the photocatalyst, so that the water repellency of the surface is permanently maintained. Also, since the surface that exhibits microscopic hydrophilicity is exposed on the surface,
Compared to tetrafluoroethylene, it is less susceptible to static electricity and dust is less likely to adhere. If the surface exhibits a high degree of water repellency of 140 ° or more, the water droplets cannot essentially adapt to the surface. Therefore, the surface of the member can easily cause attached water droplets to flow and leave no trace of water.

In another aspect of the present invention, a surface layer containing photocatalytic oxide particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of a substrate, and the surface layer has a thickness of Provided is a member having a super water-repellent surface, which is smaller than the secondary particle diameter of the water-repellent fluororesin.
With such a configuration, the amorphous silica and / or photocatalytic oxide particles in the surface layer are exposed to the outside and exhibit hydrophilicity, and the water-repellent fluororesin is exposed to the outside and exhibit water repellency. Are microscopically dispersed on the surface. In such a structure, since the hydrophilic surface and the water-repellent surface are microscopically adjacent to each other, the water droplet cannot essentially adapt to the surface. Further, by making the secondary particle diameter of the water-repellent fluororesin larger than the thickness of the surface layer, the water-repellent fluororesin is surely exposed, and the dispersion structure is more reliably realized, and the surface is Macroscopically, it exhibits a high degree of water repellency of 140 ° or more in terms of a contact angle with water. Furthermore, the presence of the photocatalyst maintains the surface of the water-repellent fluororesin in a clean state by the oxidative decomposition action of the photocatalyst, so that the water repellency of the surface is permanently maintained. In addition, since a microscopically hydrophilic portion is exposed on the surface, it is less likely to be charged with static electricity and dust is less likely to adhere than tetrafluoroethylene. If the surface exhibits a high degree of water repellency of 140 ° or more, the water droplets cannot essentially adapt to the surface. Therefore, the surface of the member can easily cause attached water droplets to flow and leave no trace of water.

[0007]

Next, a specific configuration of the present invention will be described. In one embodiment of the present invention, as shown in FIG. 1, a surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a substrate, and the surface layer The film thickness is smaller than the secondary particle size of the water-repellent fluororesin. Since the secondary particle size of the water-repellent fluororesin is larger than the thickness of the surface layer, the water-repellent fluororesin is surely exposed so as to come into contact with the outside air.

In another aspect of the present invention, as shown in FIG. 2, a surface layer containing photocatalytic oxide particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of the substrate, and The thickness of the surface layer is smaller than the secondary particle diameter of the water-repellent fluororesin. Since the secondary particle size of the water-repellent fluororesin is larger than the thickness of the surface layer, the water-repellent fluororesin is surely exposed so as to come into contact with the outside air.

In another embodiment of the present invention, as shown in FIG. 3, a surface layer containing photocatalytic oxide particles, silicone, amorphous silica, and a water-repellent fluororesin is formed on the surface of a substrate. And the thickness of the surface layer is smaller than the secondary particle size of the water-repellent fluororesin. Since the secondary particle size of the water-repellent fluororesin is larger than the thickness of the surface layer, the water-repellent fluororesin is surely exposed so as to come into contact with the outside air.

A photocatalyst has an energy larger than the energy gap between the conduction band and the valence band of the crystal.
A substance that can generate conduction electrons and holes by irradiating light (excitation light) with light (excitation light) of a short wavelength (excitation light). For example, oxides such as anatase type titanium oxide, rutile type titanium oxide, zinc oxide, tin oxide, ferric oxide, bismuth trioxide, tungsten trioxide and strontium titanate can be suitably used. Here, the photocatalytic oxide is
In the case of anatase type titanium oxide, rutile type titanium oxide, zinc oxide and strontium titanate, the light source used for photoexcitation of the photocatalyst is sunlight, indoor lighting, fluorescent light,
Mercury lamps, incandescent lamps, xenon lamps, high-pressure sodium lamps, metal halide lamps, BLB lamps and the like can be suitably used. When the photocatalytic oxide is tin oxide, a germicidal lamp, a BLB lamp, or the like can be suitably used. For photoexcitation of the photocatalyst, the illuminance of the excitation light is 0.001.
mW suffices / cm ² or more, but preferably that it 0.01 mW / cm ² or more, and more preferably it 0.1 mW / cm ² or more.

The silicone has an average composition formula R _p SiO _{(4-p) / 2} (where R is a functional group comprising one or more monovalent organic groups, or a monovalent organic group). A resin represented by the following formula: X is an alkoxy group or a halogen atom, and p is a number satisfying 0 <p <2. Is available.

As the water-repellent fluororesin, polytetrafluoroethylene, polychlorotrifluoroethylene, polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer and the like can be suitably used. Here, the secondary particle size of the water-repellent fluororesin refers to the particle size of an aggregate of fluororesin particles (primary particles) observed under an electron microscope.

The thickness of the surface layer is preferably set to 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. More preferably, the thickness of the surface layer is 0.2 μm or less. Then, it is possible to prevent the surface layer from being colored by light interference. Also, the thinner the surface layer, the better its transparency. Further, when the film thickness is reduced, the wear resistance of the surface layer is improved.

A metal such as Ag, Cu, or Zn can be added to the surface layer. The surface layer to which the metal is added can kill bacteria and fungi attached to the surface even in a dark place.

Pt, Pd, Ru, Rh, I
A platinum group metal such as r or Os can be added.
The surface layer to which the metal is added can enhance the redox activity of the photocatalyst, and can improve the decomposability of organic contaminants and the decomposability of harmful gases and odors.

The substrate to which the present invention can be applied includes metals, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, cloth, combinations thereof, and laminates thereof. It can be suitably used. The substrate to which the present invention can be applied has any problem that can be solved by making the surface super-water-repellent, such as drip-proofness of the surface, water-repellency, water-based dirt adhesion prevention, running water washing, and ice and snow prevention. Applicable to substrates.

[0017] As a substrate which is required to have a drip-proof surface,
Vehicle window glass, such as side glass for automobiles, window glass for railway vehicles, windshields for vehicles, windshields for vehicles such as motorcycles, vehicle door mirrors for automobiles, back mirrors for motorcycles, etc. Vehicle lighting covers such as mirrors, automobile headlight covers, motorcycle headlight covers, instrument panel covers such as automotive instrument panel covers, architectural window glasses, roads Transparent base materials such as mirrors, outdoor lighting covers, spectacle lenses, goggles, helmet shields for motorcycles, camera lenses, camera lens covers, mirror base materials (or films to be adhered thereon) Insulation that loses visibility due to the attachment of raindrops, etc .; Insulation due to the attachment of water droplets, such as insulators (or films attached to it), reduces the electrical insulation; Fins for heat exchangers (or attached on them) Film As in, which reduces efficiency by connecting the water droplets in the air passage; and can be suitably used.

Base materials requiring surface drainage include tableware, bathtubs, toilets, washbasins, kitchen sinks, sinks, cooking ranges, dishwashers, dish dryers, cupboards, drainboards, bathroom floors. Good surface drainage, such as wood, bathroom wall materials, bathroom ceiling materials, vehicle exteriors and coatings (or films attached to them), so that they dry quickly and prevent the growth of microorganisms due to water adhesion. It can be suitably used for a substrate that can be expected.

The base material required to prevent water-based dirt from adhering to the surface includes tableware, bathtubs, toilets, sinks, kitchen sinks, sinks, cooking ranges, dishwashers, dish dryers, cupboards, drainboards, Like bathroom floor materials, bathroom wall materials, bathroom ceiling materials, aircraft, seaside buildings (or films attached to them), scales, calcium salts and magnesium salts adhere to the surface, In addition, those which show stains in appearance due to their appearance; those which adhere to an alkali salt, such as concrete-based building materials, and diffuse inward for a long time to attack the core material can be suitably used.

[0020] The base material which is required to be capable of washing the surface with running water includes building materials, building exteriors, window frames, architectural windowpanes, vehicle windowpanes, vehicle exteriors and coatings, signs, traffic signs, road noise barriers, Sound insulation walls for railways, exteriors and coatings of garages,
Outdoor lighting covers, bridges, insulators, solar cell covers, solar water heater heat collecting covers, vinyl houses, vehicle lighting covers, line of sight guides, road reflectors, road decorative boards, railing, Outdoor components that can be cleaned by being exposed to rain, such as vehicle mirrors, outdoor surveillance cameras (or films affixed thereon); tunnel interiors and paints, building materials, building interiors, window frames, windowpanes, Housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchenware, dishes, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods,
A member that can be washed with running water, such as a ventilation fan, a bathroom floor material, a bathroom wall material, a bathroom ceiling material, a kitchen sink (or a film stuck thereon), and the like can be preferably used.

As the base material which is required to have the ability to prevent icing and snow on the surface, a roofing material, an antenna, a power transmission line, an ice and snow glider, and the like can be suitably used.

In addition, the present invention can also be used for a substrate, such as an inner wall of a vacuum vessel (or a film to be adhered thereon), which requires rapid removal of moisture attached to the surface of the substrate, and a biocompatible material. There is.

Next, a method for producing an antifouling member in which a surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a substrate will be described. The production method in this case is basically based on applying a coating composition on the surface of a substrate and curing the coating composition.

The coating composition contains, as essential components, a silicone precursor in addition to the photocatalyst particles and the water-repellent fluororesin, and a solvent such as water, ethanol and propanol, and the like. Catalysts for promoting hydrolysis of silicone precursors such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and maleic acid; and basic compounds such as tributylamine and hexylamine;
Catalysts for curing silicone precursors such as acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate;
A surfactant or the like for improving the dispersibility of the tinting liquid may be added.

[0025] Here silicone - The precursor emissions in the average composition formula _{R p SiX q O (4-} pq) / 2 ( wherein, R consists of one or more organic groups monovalent functional X or a functional group comprising two or more selected from a monovalent organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are 0 <p <2, 0 <
a film-forming element composed of a siloxane represented by the following formula: q <4) or a general formula R _p SiX _4-p (where R is one or more monovalent organic groups) Wherein X is an alkoxy group or a halogen atom, and p is 1 or 2. A film-forming element comprising a hydrolyzable silane derivative to be
Can be suitably used.

Here, as the coating film forming element comprising the hydrolyzable silane derivative, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, Phenyltributoxysilane,
Dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenyl Methyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxydoxypropyltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane and the like can be suitably used.

The film-forming element composed of the siloxane includes partial hydrolysis and dehydration condensation polymerization of the hydrolyzable silane derivative, or partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, and the like. It can be produced by dehydration polycondensation with a partial hydrolyzate such as silane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

The coating method of the coating composition includes spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge. A method such as coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

Next, a method for producing an antifouling member in which a surface layer containing photocatalyst particles, amorphous silica and a water-repellent fluororesin is formed on the surface of a substrate will be described. The production method in this case is basically based on applying a coating composition on the surface of a substrate and curing the coating composition.

The coating composition contains silica particles or a silica precursor in addition to the photocatalyst particles and the water-repellent fluororesin as essential components. In addition, a solvent such as water, ethanol, propanol or the like may be used. , Hydrochloric acid, nitric acid, sulfuric acid, acetic acid, maleic acid and other catalysts for promoting hydrolysis of silica precursors, basic compounds such as tributylamine and hexylamine, aluminum triisopropoxide and tetraisopropyl titanate For example, a catalyst for curing a silica precursor such as an acidic compound such as an acidic compound, or a surfactant for improving dispersibility of a coating liquid such as a silane coupling agent may be added.

Here, as the precursor of the silicone, the average composition formula SiX _q O _{(4-q) / 2} (where X is an alkoxy group or a halogen atom, and q is 0 <q <4 A film-forming element comprising a silicate represented by the following formula: or a general formula SiX ₄ (wherein R is a functional group comprising one or more monovalent organic groups, or X is an alkoxy group or a halogen atom), and a coating film comprising a tetrafunctional hydrolyzable silane derivative represented by the following formula: Forming elements and the like can be suitably used.

Here, as the coating film forming element comprising the above-mentioned tetrafunctional hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,
Tetrabutoxysilane, diethoxydimethoxysilane and the like can be suitably used.

The coating film-forming element comprising the above silicate can be prepared by partial hydrolysis, dehydration condensation polymerization or the like of the above tetrafunctional hydrolyzable silane derivative.

The coating method of the above coating composition includes spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge. A method such as coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

[0035]

EXAMPLE An anatase type titanium oxide sol (Nissan Chemical, T
A-15) and silica sol (Nippon Synthetic Rubber, Glaska T)
Liquid A 2202), methyltrimethoxysilane (Nippon Synthetic Rubber, liquid B of Glasca T2202), and polytetrafluoroethylene (PTFE) particles (Daikin Industries, Lubron L-5, primary particle diameter 0.2 μm, Secondary particle diameter 7μ
m) and ethanol, and the coating solution obtained by stirring for 2-3 minutes was sprayed to give 5 × 10 5
cm square glazed tile base material (TOTO KIKI, AB02E11)
Coated on top and heat-treated at 200 ° C. for 10 minutes to give a film thickness of 5 μm comprising 33 parts by weight of anatase type titanium oxide particles, 66 parts by weight of polytetrafluoroethylene particles, 6 parts by weight of silica and 5 parts by weight of silicone. A sample # 1 having the surface layer formed was obtained. The contact angle of the # 1 sample with water was 140 °. Then, an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) was used to apply 0.3 mW /
Irradiation was performed for one day at an ultraviolet irradiance of cm ² to obtain a # 2 sample. As a result, the contact angle of the # 2 sample with water showed a tendency to slightly increase to 146 °. This is due to the photocatalytic effect of silica
The organo group bonded to the silicon atom in the molecule is replaced with a hydroxyl group, and the silicone exposed to the outside air exhibits hydrophilicity. It is considered that a structure in which both the exposed portions exhibiting water repellency are microscopically dispersed on the surface is more reliably realized.

Next, for the # 2 sample and a tetrafluoroethylene plate (contact angle with water: 105 °), the dropping property of water droplets was examined. As a result, 9
Water droplets finally migrated from the adhered surface when tilted near 0 °. However, water marks were not completely removed from the surface, but water marks were left on the marks where the water had moved so as to draw a string.
On the other hand, in the sample # 2, the water droplet rolled at an inclination of about 20 °, and no residual water was observed at any trace of the movement of the water.

[0037]

According to the present invention, the surface of a substrate exhibits a super water repellency of 140 ° or more in terms of a contact angle with water, and the super water repellency can be maintained permanently. Therefore, it is possible to add properties such as drip-proof property, water-based dirt adhesion preventing property, running water washing property, and snow accretion preventing property to the base material.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface structure of a member according to the present invention.

FIG. 2 is a diagram showing another surface structure of the member according to the present invention.

FIG. 3 is a diagram showing another surface structure of the member according to the present invention.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI C09D 183/04 C09D 183/04

Claims (3)

[Claims] 1. A surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a substrate, and the surface layer has a thickness of 2
A member having a super water-repellent surface, which is smaller than the secondary particle diameter. 2. A surface layer containing photocatalytic oxide particles, amorphous silica, and a water-repellent fluororesin is formed on a surface of a substrate, and the film thickness of the surface layer is the same as that of the water-repellent fluororesin. A member having a super water-repellent surface, which is smaller than the secondary particle diameter. 3. A surface layer containing photocatalytic oxide particles, silicone, amorphous silica, and a water-repellent fluororesin is formed on the surface of the substrate, and the surface layer has a water-repellent film thickness. A member having a super water-repellent surface, wherein the member has a smaller secondary particle diameter than a fluororesin.