JP4165941B2 - Composite material capable of controlling wettability with surface water, method for controlling wettability with surface water, and functional coating liquid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a composite material characterized in that the wettability of the surface can be increased or decreased by heat treatment at a relatively low temperature, and a coating liquid for obtaining the composite material. Further, the present invention relates to members and equipment using this heat treatment control.
[0002]
[Prior art]
Various studies have been made on the surface of a member so as to have a hydrophilic or hydrophobic function depending on the use environment and application. Fields where it is preferable to make the surface hydrophilic include anti-fogging, drip-proof materials, and self-cleaning materials using rainwater. The hydrophilic member is provided with a structure having a function with high affinity for water on the surface, and prevents the transparency of the glass or the like due to condensation from being impaired by allowing the adhering moisture to blend in and spreading water droplets. The filth adhering to the surface is lifted up by rainwater and washed away to exert a self-purifying function. When it divides roughly about the conventional hydrophilic member,
a) Coating of surfactant: A surfactant is coated on the surface of a member, and when a water droplet adheres thereto, the surfactant enters the water droplet to reduce the surface tension of the water droplet and spread the water droplet.
b) Water-soluble resin coating: For example, JP-A-5-263069 discloses a composition for imparting anti-condensation, which is mainly composed of a polyvinyl alcohol-based resin, which is a water-soluble resin having a high affinity for water.
c) Porous material: A silica having a relatively high affinity with water is formed in a porous shape to increase the specific surface area, thereby providing a high hydrophilic function.
d) Member utilizing photocatalyst: A recently established technique, for example, WO96 / 29375 discloses a method of hydrophilizing the surface of a substrate, a group having a superhydrophilic photocatalytic surface. A material and a method for manufacturing the same are disclosed. The method using a photocatalyst requires irradiation with ultraviolet rays as excitation light in order to develop a hydrophilic function.
On the other hand, as a field where it is suitable to make the surface of a member hydrophobic, there is a windshield of a car. If the surface is exposed to strong wind, such as the windshield of a car, the adhering water spreads and water drops disappear when the surface is hydrophilic.However, due to the strong wind, the thickness of the water film becomes uneven and the image is distorted and the visibility is lost. Therefore, visibility is improved more by making the surface hydrophobic and blowing water droplets on the surface. For the main conventional hydrophobic members,
e) Fluorine-based resin coating: For example, by coating a water-repellent material such as polytetrafluoroethylene (PTFE) with low surface energy, it has the function of repelling water by eliminating affinity with polar molecules such as water. Is expressed.
However, the conventional techniques of the hydrophilic member and the hydrophobic member described in the above a) to e) have problems such as durability and restrictions on the use environment. In the method of imparting hydrophilicity to the surface by coating with a) a surfactant and b) a water-soluble resin, the active ingredient for hydrophilizing the surface dissolves and the amount gradually increases when used in a humid environment. There is a problem of durability such that the hydrophilic function cannot be exhibited because the active ingredient disappears in the end and the active ingredient disappears. In addition, c) a method of imparting hydrophilicity to the surface using a porous material, and e) a method of imparting hydrophobicity to the surface by coating with a fluororesin, filth adheres to the surface during long-term use. As a result, the hydrophilic function and the hydrophobic function are gradually deteriorated, and there is a problem in durability that the wettability of the surface cannot be maintained. d) The method of imparting hydrophilicity to the surface by utilizing a photocatalyst is the effect that the surface becomes very high in affinity with water by irradiating with ultraviolet rays, and further, the organic substance adhering to the surface by the photocatalytic action Due to the synergistic effect of the decomposition action, this is a technology with extremely high surface hydrophilic durability in an environment irradiated with ultraviolet light. However, a hydrophilic member using a photocatalyst needs to be irradiated with ultraviolet rays, and thus has a problem of being restricted by the use environment. Further, when using a photocatalyst, the surface can be made hydrophilic by irradiation with ultraviolet rays, but it has not been possible to control the once hydrophilized member to be hydrophobic.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned facts, and the object of the present invention is to provide a method for controlling wettability with water on the surface without using ultraviolet rays , a self-purifying product, a visibility improving member, a printing apparatus, and the like. The object is to provide an antifogging member .
[0004]
[Means for Solving the Problems]
The present invention is a method for controlling the wettability of the surface of a functional coating bonded to the surface of a substrate with water, wherein the functional coating is made of titanium oxide, iron oxide, chromium oxide, or tungsten oxide. consisting comprises at least one semiconductor selected from the group, the control, by heat treatment of the functional coating, the wettability to reversibly change the hydrophilicity and hydrophobicity of the surface of the functional coating Provide a control method.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The composite material according to the present invention is a functional film containing one kind of semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, tin oxide, zinc oxide, strontium titanate, tungsten oxide, copper oxide, or A functional film containing two or more types of semiconductors selected from the group consisting of the semiconductors, or at least one type selected from the group consisting of the semiconductors, chromium, vanadium, niobium, iron, copper, cobalt, nickel, manganese A functional film containing at least one kind of metal selected from the group consisting of:
[0006]
The functional film is formed by, for example, preparing a coating solution obtained by diluting a metal alkoxide in a solvent, and spray coating, flow coating, spin coating, dip coating, roll coating on the surface of the substrate such as glass. After coating by a method such as, the surface layer is fixed to the substrate by a method such as firing. In the case where the substrate is glass containing alkali network modifying ions such as sodium, an intermediate layer such as silica may be formed between the substrate and the surface layer. If it does so, it will prevent that an alkali network modification ion diffuses from a base material to a surface layer during baking.
[0007]
At least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, tin oxide, zinc oxide, strontium titanate, tungsten oxide, copper oxide, chromium, vanadium, niobium, iron, copper, cobalt, When compounding at least one kind of metal selected from the group consisting of nickel and manganese, for example, a liquid obtained by dripping a solution containing metal ions to be complexed with the coating liquid can be suitably used as a coating agent. it can. It is also possible to composite a metal by a plasma treatment method, an ion implantation method, or the like after a functional film not previously combined with a metal is prepared. In any case, the functional coating is desirably dense enough to prevent moisture from penetrating.
[0008]
Surprisingly, the composite material provided with the functional coating can control the wettability of the surface with water by the heat treatment temperature. More specifically, in the range of 25 ° C. to 500 ° C., it is hydrophobized in the low temperature range and hydrophilic in the high temperature range. When iron oxide was used as the semiconductor of the functional coating, as a result, it was hydrophobized by heat treatment at 25 ° C. to 200 ° C. and hydrophilized by heat treatment at 200 ° C. to 500 ° C. The mechanism by which the surface is hydrophobized by heat treatment in a low temperature region is considered to be caused by desorption of adsorbed water such as physical adsorbed water and chemically adsorbed water on the surface. In addition, the following two models are considered for the mechanism of hydrophilization at high temperatures. 1) Cleaning by burning organic substances adhering to the surface, 2) Oxygen defects are generated on the semiconductor surface in the temperature rising process, and water is dissociated and adsorbed on the oxygen defect portions in the cooling process to be stabilized.
[0009]
As a heat source used for the heat treatment, an electric furnace, a dryer, a hot plate, a high-frequency induction furnace, an electric heater, a gas furnace, a gas burner, frictional heat, or the like can be suitably used. Moreover, light irradiation with a heating effect can also be utilized as a heat source. As a light source in this case, use at least one selected from the group consisting of a fluorescent lamp, an incandescent lamp, a mercury lamp, a xenon lamp, a mercury-xenon lamp, a halogen lamp, a metal halide lamp, a laser beam, an infrared lamp, and sunlight. Or a light source in which light from the light source is guided by a low-loss fiber can be suitably used. When a light source is used as a heat source, the temperature of the object to be irradiated can be adjusted by the light amount and the irradiation wavelength. Moreover, it is also possible to combine a heat source and a light source as a heat treatment method.
[0010]
The semiconductor forming the functional film may have a photocatalytic function. For example, when titanium oxide is used as a semiconductor of the functional coating, it has a function of hydrophilizing by irradiating ultraviolet rays in addition to the function of hydrophilizing by high-temperature heat treatment and hydrophobizing by low-temperature heat treatment. Therefore, as a method for hydrophilizing the titanium oxide, in addition to high-temperature heat treatment and light irradiation for increasing the surface, hydrophilicity occurs by irradiation with light including ultraviolet rays even when the surface does not reach a high temperature. As a method for hydrophobizing the titanium oxide, low-temperature heat treatment and light irradiation that does not contain ultraviolet rays that keep the surface temperature relatively low during the irradiation process can be used. In other words, when titanium oxide is used as the semiconductor of the functional coating, the wettability of the surface with water can be controlled by appropriately adjusting the heat treatment temperature from the heat source and the light source and the light irradiation wavelength from the light source. It is.
[0011]
By combining the composite material of the present invention with a heat source and a light source, a self-cleaning product is obtained. As a self-cleaning product, a case where hydrophilicity is suitable and a case where hydrophobicity is suitable are assumed depending on the type of dirt and the environment used. For example, in the case of an outdoor building, it is more suitable as a self-cleaning product if it is a hydrophilic member that can wash away dust and particles accumulated on the roof and outer wall by rain. On the other hand, in a space where rainfall cannot be expected, such as an indoor environment, a hydrophobic member to which dust and particles hardly adhere is more suitable. Since the self-cleaning product including the composite material can be converted into a hydrophilic member or a hydrophobic member by heat treatment, the wettability of the surface with water can be appropriately controlled depending on the type of dirt and the environment used. it can.
[0012]
By combining the composite material of the present invention with a heat source and a light source, an antifogging member and a visibility improving member are obtained. Since the surface of the composite material can be hydrophilized by heat treatment at a high temperature, it can be suitably used as an antifogging member. Further, the surface of the composite material can be hydrophobized by heat treatment at a low temperature, and the hydrophobized member can be suitably used as a member for improving the visibility of a portion exposed to a strong wind such as a windshield of a car.
[0013]
A printing apparatus is provided by including the composite material of the present invention, a heat source, and a light source. By performing heat treatment on the surface of the composite material, hydrophilic and hydrophobic patterning of the surface is performed. A printed material is obtained by adhering a colored material such as a hydrophilic or hydrophobic coloring matter, toner, ink, or the like to the surface by a method such as coating, spraying, or dipping, in close contact with the substrate. Since the composite material reversibly changes its hydrophilicity and hydrophobicity depending on the heat treatment temperature, the printing apparatus including the composite material can withstand use any number of times.
[0014]
【Example】
Example 1
Iron triisopropoxide was dissolved in isopropyl alcohol to prepare a coating agent. A film was formed by spin coating on a glass substrate coated with the prepared coating agent. Spin coating was performed for 10 seconds at a rotational speed of 1500 rpm, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. From the result of X-ray diffraction, it was confirmed that the fired film was α-Fe2O3 having a corundum crystal structure. The film was stored in the dark until the contact angle with water on the surface was stabilized, and then the surface of the film was irradiated with light having a heating effect, and the contact angle with water with respect to the irradiation time was measured. Further, the surface temperature of the sample during the light irradiation process was measured with a thermocouple. The light source is a 150W xenon lamp (Hayashi Watch Industry, LA-150Xe), and the contact angle with water is determined by dropping water droplets from a microsyringe using a contact angle measuring instrument (Kyowa Interface Science, CA-X150). It was.
As a result, the contact angle with water of the film stored in the dark place after film formation is 30 ° as shown in FIG. 1, but the contact angle with water becomes 110 hours after about 60 minutes by irradiating light. Hydrophobized to ° C. The surface temperature of the sample during the light irradiation process was 100 ° C.
[0015]
Example 2
The composite material obtained in Example 1 was stored in the dark until the contact angle with the surface water became stable, and then heat treatment at 200 ° C. and 400 ° C. was repeated. A 200 ° C heat treatment was performed using a thermostatic bath, and a 400 ° C heat treatment was performed using a muffle furnace. The contact angle with water after each heat treatment step was measured.
As a result, as shown in FIG. 2, the contact angle with water on the surface is hydrophilized to about 5 ° by heat treatment at 400 ° C., and the contact angle is hydrophobized to 70 ° by heat treatment at 200 ° C., and this phenomenon is repeatedly induced. It was possible.
[0016]
Example 3
A chromium oxide coating agent (SYM-CR015, high purity chemical, oxide concentration 0.15 mol / l) was coated on a silica-coated glass substrate by spin coating. Spin coating was performed for 10 seconds at a rotational speed of 1500 rpm, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. From the result of X-ray diffraction, it was confirmed that the fired film was Cr2O3 having a corundum crystal structure. The film was stored in the dark until the contact angle with water on the surface was stabilized, and then the contact angle with water when irradiated with light having a heating effect was measured. The light irradiation conditions are the same as in Example 1. In addition, the surface temperature of the sample during the light irradiation process was measured.
As a result, as shown in FIG. 3, the contact angle with water was made hydrophobic by irradiating with light up to 110 °. The surface temperature of the sample during the light irradiation process was 100 ° C.
[0017]
Example 4
The photocatalytic functional material obtained in Example 3 was hydrophobized by light irradiation until the contact angle with water reached 110 °, and then heat-treated at 500 ° C. for 30 minutes.
As a result, the heat treatment at 500 ° C. for 30 minutes hydrophilized the contact angle with water which was 110 ° to 0 °.
[0018]
Example 5
Tungsten pentaethoxide was dissolved in isopropyl alcohol to prepare a coating agent. A film was formed by spin coating on a silica-coated glass substrate. Spin coating was performed for 10 seconds at a rotational speed of 1500 rpm, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. From the result of X-ray diffraction, the fired film was confirmed to be WO3 having a rhenium oxide type crystal structure. After storing this film in the dark until the contact angle with water on the surface becomes stable, repeat the heat treatment at 200 ° C and 400 ° C on the surface of this film and measure the contact angle with water after each heat treatment step. did. The heat treatment conditions are the same as in Example 2.
As a result, as shown in FIG. 4, it was possible to hydrophobize up to about 40 ° by heat treatment at 200 ° C. and to hydrophilize it to 5 ° or less by heat treatment at 400 ° C., and this phenomenon could be induced repeatedly.
[0019]
Example 6
A coating agent is prepared by adding dropwise a solution in which a chromium salt is dissolved in hydrochloric acid to hydrolyze titanium tetraisopropoxide. The amount of chromium added was 3% by weight with respect to titanium oxide. The prepared coating agent was spin-coated on a Pyrex glass substrate coated with silica. Spin coating was performed for 10 seconds at a rotational speed of 1500 rpm, and the coated film was baked in an electric furnace at 500 ° C. for 30 minutes. This film is again formed under the same conditions with a titanium-only coating agent to which chromium is not added. The intermediate layer is a composite layer of titanium oxide and chromium, and the surface layer is a layer of only titanium oxide. A film having a two-layer structure formed by the above was prepared. The surface of this sample was irradiated with ultraviolet light → visible light, and the change in contact angle with water with respect to the irradiation time was measured. Moreover, the temperature of the sample surface in the light irradiation process was measured with a thermocouple. The ultraviolet light source was a 200 W mercury-xenon lamp (Hayashi Watch Industries, LA-210UV), and the wavelength was set to 360 nm through a colored glass filter (Toshiba Glass, UV-D36B). The visible light source is a 150W xenon lamp (Hayashi Watch Industry, LA-150Xe), which passes through an ultraviolet light cut filter (Toshiba Glass, Y-43) and a heat ray cut filter (Toshiba Glass, IRA-25S). The irradiation wavelength was set to 430 nm to 800 nm.
As a result, as shown in FIG. 5, the contact angle with water was hydrophilized to 5 ° by ultraviolet irradiation, and the contact angle with water was hydrophobized to 20 ° by visible light irradiation. The surface temperature of the sample when irradiated with ultraviolet light was 28 ° C., and the surface temperature of the sample when irradiated with visible light was 100 ° C.
[0020]
【The invention's effect】
According to the present invention, at least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, tin oxide, zinc oxide, strontium titanate, tungsten oxide, copper oxide, or the group consisting of the semiconductors At least one kind or a plurality of film structures selected can arbitrarily control the wettability of the surface with water depending on the heat treatment temperature. By combining this composite material with a heat source or a light source having a heating effect, A hydrophilic member, a hydrophobic member, a self-purifying product, an antifogging member, a visibility improving member, and a printing device can be provided.
[Brief description of the drawings]
FIG. 1 is a graph showing a relationship between a contact angle of a sample surface with water and a light irradiation time according to Example 1 of the present invention.
FIG. 2 is a graph showing the relationship between the contact angle with water on the surface of a sample after heat treatment and the heat treatment temperature according to Example 2 of the present invention.
FIG. 3 is a graph showing the relationship between the contact angle between the sample surface and water and the light irradiation time according to Example 3 of the present invention.
FIG. 4 is a graph showing the relationship between the contact angle with water on the sample surface after heat treatment and the heat treatment temperature according to Example 5 of the present invention.
FIG. 5 is a graph showing the relationship between the contact angle of the sample surface with water and the light irradiation time according to Example 6 of the present invention.

Claims (9)

A method for controlling wettability with water on the surface of a functional coating bonded to the surface of a substrate, wherein the functional coating is selected from the group consisting of titanium oxide, iron oxide, chromium oxide, and tungsten oxide At least one kind of semiconductor, wherein the control reversibly changes the hydrophilicity and hydrophobicity of the surface of the functional coating by heat treatment of the functional coating . Control method. The wettability control method according to claim 1, wherein the semiconductor has a photocatalytic function. The method for controlling wettability according to claim 1 or 2 , wherein the substrate is glass. The wettability control method according to any one of claims 1 to 3, wherein a temperature of the heat treatment is in a range of 25 ° C to 500 ° C. A functional coating liquid for use in the wettability control method according to any one of claims 1 to 4 ,
An amorphous or colloidal coating solution containing a solvent and at least one selected from the group consisting of titanium, iron, chromium, and tungsten as components, which is applied to a substrate and then wetted by heat treatment A functional coating liquid characterized by having a function capable of controlling properties. A self-purifying product using the wettability control method according to any one of claims 1 to 4 ,
A substrate;
A composite material that is bonded to the surface of the base material and includes a functional film including at least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, and tungsten oxide, and a heat source. ,
The functional coating is a self-purifying product, wherein the wettability of the surface with water is controlled by heat treatment. A visibility improving member using the wettability control method according to any one of claims 1 to 4 ,
A substrate;
A composite material that is bonded to the surface of the base material and includes a functional film including at least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, and tungsten oxide, and a heat source. ,
The visibility-enhancing member, wherein the functional coating is controlled in its wettability with water by heat treatment. A printing device using the wettability control method according to any one of claims 1 to 4 ,
A substrate;
A composite material that is bonded to the surface of the base material and includes a functional film including at least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, and tungsten oxide, and a heat source. ,
The functional coating is a printing apparatus, wherein wettability with water on the surface is controlled by heat treatment. An anti-fogging member using the wettability control method according to any one of claims 1 to 4 ,
A substrate;
A composite material that is bonded to the surface of the base material and includes a functional film including at least one semiconductor selected from the group consisting of titanium oxide, iron oxide, chromium oxide, and tungsten oxide, and a heat source. ,
The anti-fogging member, wherein the functional coating is controlled in its wettability with water by heat treatment.

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