WO2006123426A1

WO2006123426A1 - Method for preparing titanium oxide film and solution for forming titanium oxide film

Info

Publication number: WO2006123426A1
Application number: PCT/JP2005/009277
Authority: WO
Inventors: Mihoko Okada
Original assignee: Axtis Company
Priority date: 2005-05-20
Filing date: 2005-05-20
Publication date: 2006-11-23

Abstract

[PROBLEMS] To provide a method for preparing a titanium oxide film which, even when the titanium oxide film is formed on a substrate containing a rubber and it is irradiated with a great amount of an ultraviolet ray, can retain the flexibility of the rubber and can prevent the deterioration of the rubber, and a solution for forming the titanium oxide film. [MEANS FOR SOLVING PROBLEMS] A method for preparing a titanium oxide film, which comprises a step of applying an aqueous solution of peroxotitanic acid containing a prescribed binder on a substrate, a step of drying the applied aqueous solution of peroxotitanic acid, followed by firing, to thereby form a first layer, a step of applying a peroxo-modified anatase sol on the above first layer and a step of drying the applied peroxo-modified anatase sol, to thereby form a second layer.

Description

Specification

Method for producing titanium oxide film and solution for forming titanium oxide film

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for producing a titanium oxide film and a solution for forming a titanium oxide film using an aqueous solution for forming an oxide titanic film containing peroxotitanic acid modified with a peroxo group.

Background art

[0002] Since the solution used to form the acid-titanium film contains no acid or organic matter, it does not need to be removed, and a dense film can be formed at low temperatures. A peroxotitanic acid aqueous solution in which the peroxo group (O—O) is modified on the particles, and a peroxo-modified anatase sol obtained by heating the peroxotitanic acid aqueous solution at 80 ° C. or higher are used. Manufacturing methods are known (see, for example, Patent Document 1 and Patent Document 2).

[0003] By the way, in general, when the base material is an organic substance, the base material itself may be decomposed by the action of the photocatalyst. However, according to the method for producing a titanium oxide film described in Patent Document 1 and the like, an aqueous peroxotitanic acid solution that is an inorganic substance is applied as a binder (protective layer) on the substrate, and the photocatalytic activity is further improved. Since a peroxo-modified anatase sol having an organic solvent is applied, it is protected by a layer formed by a peroxotitanic acid aqueous solution even when the substrate is an organic substance, so that the substrate itself is not decomposed by the action of the photocatalyst. Absent. Therefore, in principle, the method for producing the titanium oxide film does not matter what kind of substrate the film is formed on.

Patent Document 1: Japanese Patent No. 2938376

Patent Document 2: Japanese Patent Laid-Open No. 9-262481

Disclosure of the invention

Problems to be solved by the invention

[0004] However, even in the case of the titanium oxide film described in Patent Document 1 or 2 as described above, in order to make the formed titanium oxide film have photocatalytic activity, it is irradiated with ultraviolet rays. You However, as a characteristic of the titanium oxide film having photocatalytic activity, the surface hardness increases as it is exposed to ultraviolet rays (for example, the film strength becomes H or 8 H, which was pencil hardness H). Here, when rubber was included in the base material, there was a problem that the flexibility of the rubber was impaired by increasing the irradiation of ultraviolet rays and increasing the hardness of the titanium oxide film on the surface.

[0005] Also, the titanium oxide film having photocatalytic activity as described above can cut ultraviolet rays on the surface of the film, but heat is conducted and reaches the substrate. Then, there was a problem that this heat caused the rubber to deteriorate. When the above-mentioned titanium oxide film is placed indoors, it does not matter so much, but when placed outdoors, the above problems are likely to occur.

[0006] Therefore, the present invention has been made in view of such problems, and an object of the present invention is to form a titanium oxide film on a base material containing rubber, and to which a large amount of ultraviolet rays are irradiated. In this case, a new and improved method of manufacturing a titanium oxide film and a solution for forming a titanium oxide film capable of maintaining the flexibility of the rubber and preventing the deterioration of the rubber can be provided. is there.

Means for solving the problem

[0007] In order to solve the above problems, according to the first aspect of the present invention, a step of applying a peroxotitanic acid aqueous solution containing a predetermined binder to a base material having a material strength containing rubber; A step of forming a first layer by drying a peroxotitanic acid aqueous solution followed by baking; a step of applying a peroxo-modified anatase sol on the first layer; and drying the coated peroxo-modified anatase sol Forming a second layer by providing a method for producing a titanium oxide film.

[0008] In the method for producing a titanium oxide film, the predetermined noinda is at least one polymer containing a bond selected from the group consisting of Si-H, Si-C, Si-N, and Si-O forces. It is preferable that In particular, it is more preferable that the predetermined noinda includes polysiloxane or a carbonized polymer.

[0009] By using a strong polymer as the predetermined binder, it is possible to suppress the absorption of ultraviolet rays by rubber contained in the base material. This mechanism is clear However, the present inventor does not allow the polymer to act as an ultraviolet absorber and absorb ultraviolet rays, or to prevent the polymer from forming a film and reflecting or transmitting ultraviolet rays. Therefore, it is thought that the ultraviolet light absorbed by the base material is greatly reduced.

[0010] Further, the method for producing the titanium oxide film includes applying a mixed solution of a peroxotitanic acid aqueous solution and a peroxo-modified anatase sol on the second layer; and applying the applied mixed solution. A step of forming a third layer by baking after drying, and the titanium oxide film may have a three-layer structure.

In order to solve the above problems, according to a second aspect of the present invention, there is provided a peroxotitanic acid aqueous solution used for manufacturing a titanium oxide film formed on a base material having a material strength including rubber. A peroxotitanic acid aqueous solution containing 0.1 to 1% by mass of titanium oxide, a predetermined binder, and a solvent (mainly water) is provided.

Here, the predetermined binder is preferably at least one polymer containing a bond selected from the group consisting of Si—H, Si—C, Si—N, and Si—O. In particular, it is more preferable that the specified binder contains polysiloxane or a carbonized polymer.

The invention's effect

[0013] According to the present invention, even when a titanium oxide film is formed on a base material containing rubber by containing a predetermined substance in the binder layer, and a large amount of ultraviolet rays are irradiated to the titanium oxide film, It is possible to provide a method for producing a titanium oxide film and a solution for forming a titanium oxide film that can maintain rubber flexibility and prevent deterioration of rubber.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail.

First, a titanium oxide film according to an embodiment of the present invention will be described.

[0016] titanium oxide film according to the present embodiment includes a predetermined Noinda, the content of titanium oxide using Peruokisochitan acid aqueous solution is 0.1 to 1 mass ^_0/0, a material containing a rubber A first layer formed on the substrate; and a second layer formed on the first layer using a peroxo-modified anatase sol. [0017] The peroxotitanic acid aqueous solution for forming the first layer is a yellow transparent viscous liquid, and can be prepared as follows. That is, first, a water-soluble titanium compound such as tetrasalt titanium dioxide, titanium sulfate, titanium nitrate, and alkoxy titanium is dissolved in water to form an aqueous solution. Hold the solution and precipitate titania hydroxide (ortho titanic acid). Next, the titanium hydroxide gel is separated by washing with decantation using water. Furthermore, the above-mentioned peroxotitanic acid aqueous solution can be obtained by adding hydrogen peroxide water to decompose and remove excess hydrogen peroxide. This aqueous solution is considered to contain peroxytitanium hydroxide titanium, or peroxotitanium, and is essentially different from the commercially available diacid titanium sol.

[0018] Further, as the titanium source of the aqueous solution, chloride, sulfate, oxalate, etc., which are inexpensive and easy to handle, are preferable, and a basic solution for generating a precipitate of hydroxide. Ammonia water, sodium hydroxide aqueous solution and the like are preferable. In this case, a combination in which the salt by-produced by the reaction becomes a stable and harmless salt sodium salt, sodium sulfate, salt salt ammonium or the like is preferable. The concentration of the raw material solution is not particularly limited. It is preferable that the pH of the precipitation is about 2 so that impurities such as Fe do not coprecipitate.

[0019] Precipitated titanium hydroxide (ortho titanic acid) is in the form of a gel that has been polymerized by polymerization of hydroxyl groups or hydrogen bonds, and as such, it can be used as a solution for forming an acid-titanium film. Can not. When peracid-hydrogen water is added to this gel, a part of the hydroxyl group is in a peroxidized state and dissolved as peroxotitanate ion, or it is in a kind of sol state in which the polymer chain is divided into low molecules, and excess excess hydrogen is formed. Hydrogen oxide is broken down into water and oxygen. This makes it possible to use it as a solution for forming a titanium oxide film.

[0020] Since this sol contains only oxygen and hydrogen in addition to titanium, only water and oxygen are generated when it is changed to titanium oxide by drying or firing, and the sol-gel method is not suitable for thermal decomposition methods such as sulfate. Since it is no longer necessary to remove the necessary carbon and halogen components, it is possible to produce a crystalline titanium oxide film having a relatively high density even at a lower temperature than in the past. In addition, since the pH is neutral, there is no need to consider the danger to the human body or corrosion of the substrate during use. Furthermore, hydrogen peroxide not only acts as a solubilizer but also as a stabilizer, so the sol is extremely stable at room temperature and can withstand long-term storage. [0021] In the peroxotitanic acid aqueous solution prepared as described above, titanium oxide exists in an amorphous state. Therefore, the photocatalytic activity is inactive at room temperature. On the other hand, when it is heated above 250 ° C, it completely crystallizes and has high photocatalytic activity. In addition, when this peroxotitanic acid aqueous solution is used, it is possible to form a highly acidic, high-density, and smooth acid-titanium film. Therefore, peroxotitanic acid aqueous solution is mainly used as a primer (binder) at 200 ° C or lower, a film with photocatalytic functions such as antibacterial and antifouling properties at 250 ° C or higher, or a mixed film with other particles. Used to form.

[0022] In the peroxotitanic acid aqueous solution, the content of titanium oxide is 0.1 to 1% by mass in the peroxotitanic acid aqueous solution that is directly applied to the substrate and used as a protective coating. It is also a powerful force that the effect of suppressing chiking is obtained by suppressing the content of titanium oxide to 0.1 to 1% by mass.

In the present embodiment, the content of titanium oxide in the peroxotitanic acid aqueous solution is the same as that described above in the washing step after precipitation of the titanium hydroxide gel in the aqueous solution production step. ! Adjust it! /

In the present embodiment, the peroxotitanic acid aqueous solution includes a predetermined binder having a function of preventing deterioration of rubber contained in the base material. Details of this binder will be described later.

[0025] The peroxo-modified anatase sol for forming the second layer is a pale yellow transparent liquid, and is prepared by heat-treating the peroxotitanate aqueous solution at 80 ° C or higher. be able to. In other words, when the peroxotitanic acid aqueous solution is heated to 80 ° C or higher, it can be modified into a liquid in which fine particles of titanium oxide are produced. The reason why the temperature is set to 80 ° C or higher is that the crystallization of titanium oxide does not proceed sufficiently at 80 ° C or lower. A crystalline titanium oxide film can be formed at a temperature as low as 80 ° C or higher by drying the coating or heating. However, heat treatment at 200 ° C or higher is preferred for good adhesion.

[0026] The peroxo-modified anatase sol prepared in this way is a liquid containing fine particles of titanium oxide acid crystallized in anatase form (particle size is, for example, about lOnm). Above In this case, titanium oxide contains anatase-type crystals that have photocatalytic activity! Therefore, the photocatalytic effect can be obtained simply by drying at room temperature. Therefore, peroxo-modified anatase sol is mainly used to form films having photocatalytic functions such as air purification, deodorization, water purification, and antibacterial functions. In addition, the zeolite containing fine titanium oxide particles is in the neutral or weakly acidic range and does not contain substances other than titanium, oxygen and hydrogen, so it is essentially different from the commercially available titanium dioxide sol. .

[0027] Here, the mechanism of the dispersion of the acid titanium particles in the peroxo-modified anatase sol used for the production of the acid titanium film of this embodiment will be described.

[0028] In general, in order to obtain high photocatalytic activity, it is necessary to increase the surface area of the catalyst. Therefore, a fine particle having a particle size of 0: m or less, colloidal titanium oxide particles are used as a raw material. Yield force Such particles with a small particle size tend to aggregate and are difficult to disperse uniformly. Therefore, the particles are dispersed by applying electric charges to the particles and repelling them. Here, the particles usually have a charge in the strongly acidic or strongly alkaline region, and in the neutral region the charge is zero (the isoelectric point exists in the neutral region). The titanium particles are difficult to disperse. Therefore, most ordinary acid titanium sols are charged by adsorbing H + on the acid titanium particles in the strongly acidic region.

On the other hand, when the surface potential of the anatase type particles in the peroxo-modified anatase sol of this embodiment is measured, it is about −50 mV at about pH 7. This value is higher than the surface potential of general titanium dioxide particles and has an absolute value several times higher. For this reason, the present inventor has modified the peroxo group (—O—O—) on the surface of the anatase-type particle present in the solution, and the repulsive force (repulsive force) between the peroxo groups, This is because anatase-type titanium oxide fine particles can be stably dispersed even in the neutral range.

[0030] Next, the manufacturing method of the titanium oxide titanium film according to the present embodiment will be described in detail.

[0031] A method for producing a titanium oxide film according to the present embodiment includes a step of applying a peroxotitanic acid aqueous solution containing a predetermined binder to a base material such as a rubber-containing material; Forming a first layer by baking after drying; applying a peroxo-modified anatase sol on the first layer; and drying the applied peroxo-modified anatase sol to form a first layer. Forming two layers; and It is characterized by that. Specifically, the titanium oxide film according to the present embodiment can be manufactured as follows.

First, since the solutions for forming a titanium oxide film according to the present embodiment are all aqueous solutions that do not contain an organic solvent, the base material is subjected to a water repellent treatment, and an oil film adheres to it. In such a case, it is preferable to pre-treat these substrates because the above solution cannot be suitably applied to the substrates.

[0033] Such pretreatment is not particularly limited as long as it can remove the water repellent treatment or the oil film, and includes, for example, washing and washing (for example, washing using high-pressure water), interface There are cleaning using an activator, alcohol cleaning, surface wiping with an organic solvent, surface wiping with a polishing agent (fine polishing), ultrasonic cleaning, and chemical conversion treatment.

[0034] The pretreatment as described above not only facilitates the application of the solution for forming the titanium oxide film to the base material, but also results in deactivation of photocatalytic activity due to the incorporation of impurities and impurity decomposition. It is also possible to prevent pinholes in the titanium oxide film.

[0035] Here, the base material used in the production of the titanium oxide film according to the present embodiment is required to contain rubber, but other than that, there is no particular limitation. The peroxotitanic acid aqueous solution according to this embodiment, such as ceramic, ceramic, metal, plastic, fiber, building material, etc., can be applied to any substrate as long as it can withstand heat treatment according to the application. , It is also possible to perform the surface treatment of the inside of the porous body and the powder. In particular, since peroxotitanic acid aqueous solution is neutral, it is possible to effectively perform metal oxide-titanium coating.

Next, a peroxotitanic acid aqueous solution is applied to the base material that has been pretreated as described above.

At this time, the coating method is not particularly limited, and various known methods can be selected depending on the properties and shape of the substrate. Examples of the application method include a spray method, a dip method, a brush 'roll coating method, and a bar coating method.

[0037] The spray method is a method of spraying using a spray gun or the like, and manages the state of the mist sprayed by the nozzle diameter and air pressure. Normally, application is performed by a spray method using a spray gun. However, in the case of application by a spray gun, dripping or uneven spraying may occur depending on the material of the base material. There is also a disadvantage that the effect of is not obtained. On the other hand, spray gun application has the advantage of reducing the thickness of the formed titanium oxide film. For example, when the film thickness is normally 0.8 ~: m, the film can be applied with a film thickness of 0.3 ~ 0.8 m by using a rotary spray gun so that it does not scatter within a certain range. can do.

[0038] Further, the dip method is a method in which a substrate to be coated is immersed in a container containing a solution for forming a titanium oxide film, and the solution is adhered to the substrate. The amount of coating is controlled by the concentration of the solution and the dipping time. The brush 'roll coating method is a method of applying directly to the substrate using a brush or sponge roll. With this method, there is little loss of the solution for forming the titanium oxide film and it is easy and simple to apply, but irises due to uneven coating tend to occur. The bar coating method is a method of forming a uniform coated surface on a flat surface by drawing a solution placed on the target surface with a special stainless steel mesh bar.

[0039] In addition, the amount of coating, for example, applying about 200~240g per lm ^2. At this time, the thickness of the formed titanium oxide film is about 0.5 μm.

[0040] In addition, when the peroxotitanic acid aqueous solution is applied to a base material, if the surface of the base material has high water repellency, an appropriate surfactant may be added to improve the wettability with the base material. Can be added. However, if a peroxotitanic acid aqueous solution that has not been heat-treated is added with a solution containing other transition metal ions, silver ions, etc., or a strong acid or strong alkali, the titanic acid is released from the titanium solution that was in the state of gel, and the gel It should be noted that there is a possibility of hesitation. The amount of surfactant to be added should be as small as possible so that the wettability of the solution used for forming the second layer (peroxo-modified anatase sol) does not deteriorate.

Next, the applied peroxotitanic acid aqueous solution is dried. The drying method can be either natural air drying or hot air drying using a dryer! /, But in the case of natural drying, it takes about 3 to 12 hours to fix the film, so the time is shortened. For this purpose, hot air drying is preferred. The rate of cure of the titanium oxide film formed after drying the applied peroxotitanic acid aqueous solution is proportional to the temperature and the amount of ultraviolet light. Sex can be improved early. [0042] When the titanium oxide film formed of the peroxotitanic acid aqueous solution is irradiated with ultraviolet rays, the peroxo group in the titanium oxide film is decomposed and changed to amorphous titanium dioxide. As a result, the film becomes dense and the hardness increases. In such a state, the titanium oxide film becomes a solid film insoluble in water. After that, the titanium oxide film continues to harden and stabilizes at a hardness of about 2H after about 2 months in the natural state. In other words, the rate of increase in the drying film is proportional to temperature and the amount of ultraviolet light.

[0043] After the drying, the first layer is formed by firing the titanium oxide film. The above peroxotitanic acid aqueous solution forms an amorphous (amorphous state) titanium oxide film slightly containing hydroxyl groups at a firing temperature of less than 200 ° C, and is crystalline (anatase type) high-density acid solution at 200 ° C or higher. A titanium film can be formed. These films have excellent acid resistance and can be used for various anticorrosion coatings. Thus, by further baking the dried titanium oxide film, the hardness of the formed titanium oxide film can be increased and the adhesion to the substrate can be improved.

[0044] However, when the temperature is raised to 600 ° C or higher during drying or baking as described above, as the hardness of the titanium oxide film increases and the density of the titanium oxide film increases, the thickness of the titanium oxide film increases. The surface area becomes small, and the contact area force with the titanium oxide particles such as contaminants becomes small, which is not preferable.

[0045] Furthermore, if heat of 800 ° C or higher is applied to the titanium oxide film, the crystalline state of titanium oxide changes from the anatase type to the rutile type, leading to a decrease in the photocatalytic function. It is not preferable.

Next, a peroxo-modified anatase sol is further applied on the first layer to the base material on which the first layer is formed. Since the coating method and the coating amount are the same as those for forming the first layer, a detailed description is omitted. In addition, when applying peroxo-modified anatase sol on the first layer, it is basically not necessary to add a surfactant, unlike direct application to the substrate.

[0047] Next, a second layer is formed by drying the applied peroxo-modified anatase sol. The drying method may be either hot air drying or natural drying, but the hot air drying is preferred for the purpose of shortening the time as described above. [0048] In this way, the peroxo-modified anatase sol can be produced by simply drying after coating, without producing a crystalline (anatase-type) acid-titanium film. Therefore, it is particularly useful as a coating agent for substrates that cannot be heat-treated. In such a method, it can be used for various applications such as protective coatings and photocatalysts, and it is possible to obtain a comparatively high density and good adhesion at a relatively low temperature.

[0049] The step of forming the second layer may include a step of baking the applied peroxo-modified anatase sol after drying. By including the firing step in this way, the hardness of the formed titanium oxide film can be increased and the adhesion to the substrate can be further improved.

[0050] However, when the temperature is raised to 600 ° C or higher during the drying or baking as described above, the titanium oxide film has increased with the increase in hardness of the titanium oxide film and the densification of the titanium oxide film. The surface area becomes small, and the contact area force with the titanium oxide particles such as contaminants becomes small, which is not preferable.

[0051] Furthermore, if heat of 800 ° C or higher is applied to the titanium oxide film, the crystalline state of titanium oxide changes from the anatase type to the rutile type, leading to a decrease in the photocatalytic function. It is not preferable.

In the above embodiment, the case where the titanium oxide film has a two-layer force has been described. However, a mixed solution of a peroxotitanic acid aqueous solution and a peroxo-modified anatase sol is formed on the second layer. And a step of forming a third layer by baking after drying the applied mixed solution, so that the titanium oxide film has a three-layer structure. Moyo.

[0053] Next, a binder for preventing deterioration of rubber contained in the peroxotitanic acid aqueous solution, which is a characteristic part of the present embodiment, will be described.

[0054] In the method for manufacturing the titanium oxide film according to this embodiment, the predetermined binder is Si.

It is preferably at least one polymer containing a bond selected from the group consisting of —H, Si—C, Si—N and Si—O forces. For example, the predetermined noinda may include polysiloxane or a carbonized polymer. In addition, as this carbonized polymer, for example, a molybdenum carbide-based silicon in which molybdenum is bonded to the carbonized silicon. System polymers can be used.

[0055] Although it is not clear about the principle that the deterioration of rubber or the like can be suppressed by using a silicone polymer containing the above-mentioned silicone as a binder for preventing the deterioration of rubber according to this embodiment. The present inventor believes that the silicone polymer is generally excellent in heat resistance, so that the silicone polymer forms a film in the first layer described above, and this is to suppress the conduction of heat to the substrate. The

[0056] As described above, by adding the above-mentioned noinda to the peroxotitanic acid aqueous solution used in the method for manufacturing the titanium oxide film according to the present embodiment, the titanium oxide film is formed on the base material containing rubber. Even if it is formed and irradiated with a large amount of ultraviolet rays, it can maintain the flexibility of the rubber and prevent the rubber from deteriorating. As a result, even if the titanium oxide film formed on the substrate is irradiated with ultraviolet rays so that the photocatalytic activity can be maintained, the flexibility of the rubber is maintained and the deterioration of the rubber is suppressed. Can do.

[0057] While the preferred embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to such an example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

Industrial applicability

The present invention can be applied to a method for producing a titanium oxide film using an aqueous solution for forming an oxide titanic film containing peroxotitanic acid modified with a peroxo group and a solution for forming a titanium oxide film.

Claims

The scope of the claims

[1] applying a peroxotitanic acid aqueous solution containing a predetermined binder to a base material made of a material containing rubber;

The applied peroxotitanic acid aqueous solution is dried and fired.

Forming one layer;

Applying a peroxo-modified anatase sol on the first layer;

Forming a second layer by drying the applied peroxo-modified anatase sol;

A method for producing a titanium oxide film, comprising:

[2] The predetermined binder is at least one polymer containing a bond selected from the group consisting of Si-H, Si-C, Si-N and Si-O forces. A method for producing a titanium oxide film according to 1.

[3] The method for producing a titanium oxide film according to [2], wherein the predetermined binder includes polysiloxane or a silicon carbide-based polymer.

[4] applying a mixed solution of the peroxotitanic acid aqueous solution and the peroxo-modified anatase sol on the second layer;

Forming the third layer by drying and then baking the applied mixed solution;

The method for producing a titanium oxide film according to claim 1, further comprising:

[5] A peroxotitanic acid aqueous solution used for manufacturing a titanium oxide film formed on a base material made of a material containing rubber,

0.1 to 1% by weight of titanium oxide;

With a predetermined binder;

With a solvent;

A peroxotitanic acid aqueous solution characterized by comprising

6. The predetermined binder is at least one polymer containing a bond selected from the group consisting of Si-H, Si-C, Si-N, and Si-O forces. The peroxotitanic acid aqueous solution described in 1. 7. The aqueous peroxotitanic acid solution according to claim 5, wherein the predetermined binder includes polysiloxane or a silicon carbide polymer.