Photocatalytic composite membrane and method for producing the same

The present invention relates to a photocatalytic composite film and a method for producing the same. More specifically, the present invention has an undercoat layer, can easily form a film, has strong photocatalytic activity, and has film strength, abrasion resistance, and adhesion to a substrate. The present invention relates to a photocatalytic composite membrane having a high property and preventing invasion of a substrate by active oxygen, and a method for producing the same.

Anatase-type titanium oxide has a photocatalytic function of absorbing light having an energy larger than the band gap and converting oxygen into active oxygen, and exhibits various effects based on the strong oxidizing power of the generated active oxygen. For example, it is known that the photocatalytic film exhibits a self-cleaning effect when applied or formed on the outer wall of a building or the outer surface of a window glass.

The self-cleaning action of the photocatalyst film is that the photocatalyst absorbs light energy and transfers the absorbed energy to oxygen to generate active oxygen, and the generated active oxygen adheres to the outer wall and the outside of the window glass. It is based on a mechanism that oxidatively decomposes dyed products, flushes out contaminants that are easily washed away by rainwater, and keeps the outer walls and windowpanes of buildings clean, and has already been put into practical use. However, the conventional anatase-type titanium oxide photocatalyst film requires a baking process at about 400 to 700 ° C to form a film, so its application and application range are limited.

In recent years, as a method for producing anatase-type titanium oxide, anatase-type titanium oxide fine particles obtained by heating an aqueous solution of peroxotitanic acid hydrate produced by treating a titanium raw material with hydrogen peroxide at about 100 ° C. It has been disclosed that anatase-type titanium oxide photocatalyst film can be formed only by applying and drying the aqueous dispersion of Titanium oxide (see, for example, Patent Documents 1 and 2).

The anatase-type titanium oxide photocatalytic film obtained by this production method has a feature that a film can be formed simply by applying it to a substrate and drying it, and it can also exhibit photocatalytic activity by visible light. It has a problem that the film strength and adhesion are slightly inferior to those of the conventional photocatalyst baked at a high temperature.

In addition, since active oxygen released from the photocatalyst film also invades the photocatalyst, it is common that a coating film must be provided between the base material and the photocatalyst when the base material is an organic substance. There is also a problem with.

On the other hand, it is obtained by applying peroxotitanic acid hydrate, which is an intermediate of anatase-type titanium oxide, and drying it.<u style="single">Peroxotitanic acid</u>Although the film does not have a photocatalytic action, it has excellent film strength and excellent adhesion to many substrates including anatase-type titanium oxide film. Taking advantage of this feature, it was produced from peroxotitanic acid hydrate.<u style="single">Peroxotitanic acid</u>Disclosure of a method for forming a second layer composed of anatase-type titanium oxide film on the first layer composed of anatase-type titanium oxide film to strengthen the coating film, increase its adhesion, and prevent invasion of the substrate by active oxygen species. (See, for example, Patent Document 3). Patent Document 3 also discloses that amorphous titanium oxide is mixed with anatase-type titanium oxide in the catalyst layer in order to enhance the strength and adhesion. In this case, even if the strength of the film is increased, The strength of the photoactive catalyst may decrease.

However, the coating film on the outer wall of a building is required to have long-term durability of several years to a dozen years under extremely harsh environmental conditions.<u style="single">Peroxotitanic acid</u>Although it is effective to some extent to provide the undercoat layer, it may not be sufficient by itself. Therefore, it has been desired to develop a method for further strengthening the strength and adhesion of the membrane while maintaining the catalytic activity of anatase-type titanium oxide.

<p num="0009"><patcit num="1"><text>Japanese Patent No. 3490013</text></patcit><patcit num="2"><text>Japanese Patent No. 2938376</text></patcit><patcit num="3"><text>Japanese Patent No. 3690864</text></patcit></p>

<p num="0010"> The present invention has been made to solve the above-mentioned problems, and the subject of the present invention is a strong adhesion at a practical level that can withstand the harsh environmental conditions to which the exterior of a building is exposed. It is an object of the present invention to provide a photocatalytic composite film containing anatase-type titanium oxide, which has properties and coating film strength, has a strong self-cleaning effect by photocatalytic action, and effectively shields the invasion of active oxygen into a substrate. ..</p><p num="0011"> The present invention also provides a photocatalytic composite film containing anatase-type titanium oxide, which can form a film simply by coating, has good film forming property and adhesion, has high catalytic efficiency, and is inexpensive, and a method for producing the same. The task is to do.</p>

<p num="0012"> The photocatalytic composite film of the present invention for solving such a problem is<u style="single">Peroxotitanic acid</u>It also has an undercoat layer containing reinforcing particles having an average particle size of 5 to 500 μm and a Mohs hardness of 5 or more, and a photocatalyst layer containing anatase-type titanium oxide formed on the undercoat layer.<u style="single">Converted to titanium oxide of peroxotitanic acid</u>When the mass is 100 parts by mass, the mass of the reinforcing particles is 1 to 100 parts by mass.</p><p num="0013"> The present invention is also characterized in that the reinforcing particles are one or more of the particles of feldspar, silica gel, silica gel, alumina, or titania. Further, in the present invention, the coating amount of the undercoat layer is<u style="single">Peroxotitanic acid converted to titanium oxide</u>The amount of coating is 0.1 ~ 100g / m²Is preferable. The amount of titanium oxide applied to the photocatalyst layer is 0.1 to 50 g / m.²Is preferable.</p><p num="0014"> Further, in the present invention, the photocatalyst layer is further formed.<u style="single">Peroxotitanic acid</u>It is characterized by including. Further, in the present invention, the coating amount of the photocatalyst layer is the coating amount of anatase-type titanium oxide.<u style="single">Converted to titanium oxide of peroxotitanic acid</u>The total mass of the coating amount is 0.1 to 50 g / m.²And with the mass of anatase-type titanium oxide<u style="single">Mass of peroxotitanic acid converted to titanium oxide</u>The ratio with and is in the range of 1: 0 to 1: 2 (excluding 0).</p><p num="0015"> The method for producing the photocatalytic composite film of the present invention is a peroxotitanate aqueous solution manufacturing step for producing a peroxotitanate aqueous solution from a titanium raw material, and a peroxotitanate aqueous solution having an average particle size of 5 to 500 μm and a moth hardness of 5 or more. The mass of certain strengthened particles converted from the mass of peroxotitanic acid contained in the aqueous solution of peroxotitanate to the mass of titanium oxide (hereinafter referred to as "converted").<u style="single">T</u>iO₂When "mass" is 100 parts by mass, the undercoat liquid manufacturing process of adding 1 to 100 parts by mass to produce an undercoat liquid, and the undercoat liquid is applied to the surface of the substrate and dried.<u style="single">Peroxotitanic acid</u>An undercoat layer forming step of forming an undercoat layer containing and strengthened particles, a photocatalyst solution manufacturing step of heating a peroxotitanic acid aqueous solution to produce a photocatalyst solution containing anatase-type titanium oxide dispersion, and a photocatalyst solution undercoating. It is characterized by having a photocatalyst layer forming step of applying it on a coat layer and drying it to form a photocatalyst layer.</p><p num="0016"> The present invention is also characterized in that the reinforcing particles are one or more of the particles of feldspar, silica gel, silica gel, alumina, or titania. Further, in the present invention, the content of peroxotitanate contained in the peroxotitanate aqueous solution is "converted" of peroxotitanate when the mass of the peroxotitanate aqueous solution is 100 parts by mass.<u style="single">T</u>iO₂The "mass" is preferably 0.1 to 20 parts by mass.</p><p num="0017"> The mass of the strengthening particles contained in the undercoat liquid is 0.1 to 20 parts by mass when the mass of the undercoat liquid is 100 parts by mass. The amount of the undercoat liquid applied is the "converted amount" of peroxotitanic acid contained in the undercoat liquid.<u style="single">T</u>iO₂"Mass" is 0.1 ~ 500g / m²It is preferable to apply so that</p><p num="0018"> The content of anatase-type titanium oxide contained in the photocatalyst solution is preferably 0.1 to 20 parts by mass when the mass of the photocatalyst solution is 100 parts by mass. Further, in the present invention, the amount of the catalyst solution applied is 0.1 to 250 g / m in terms of the mass of titanium oxide contained in the photocatalyst solution.²It is preferable to apply so that</p><p num="0019"> Further, the present invention is characterized in that the photocatalytic solution further contains a peroxotitanic acid aqueous solution. When the mass of the photocatalyst solution is 100 parts by mass, the mass of anatase-type titanium oxide and the "conversion of peroxotitanic acid"<u style="single">T</u>iO₂The total of "mass" is 0.1 to 20 parts by mass, and the mass of anatase-type titanium oxide and "converted" of peroxotitanic acid<u style="single">T</u>iO₂The "mass" ratio is preferably in the range of 1: 0 to 1: 2.</p>

<p num="0020"> The photocatalytic composite film of the present invention has excellent film strength and adhesiveness.<u style="single">Peroxotitanic acid</u>The strength of the photocatalyst film is obtained by blending the undercoat layer of the above with reinforcing particles having an average particle size of 5 to 500 μm and a Mohs hardness of 5 or more, forming recesses between the reinforcing particles to protect the photocatalyst film. And wear resistance was improved. Also, on the photocatalytic membrane<u style="single">Peroxotitanic acid</u>The strength and abrasion resistance of the photocatalyst film were further improved by adding.</p><p num="0021"> Further, the photocatalytic composite film of the present invention is<u style="single">Peroxotitanic acid</u>By having the undercoat layer containing the above and the photocatalyst layer containing anatase-type titanium oxide formed on the undercoat layer, the adhesion between the base material and the photocatalyst film is enhanced, the film strength is improved, and the photocatalytic reaction is performed. By blocking the invasion of the base material by the active oxygen generated by, the durability of the coating film and the equipment was improved.</p><p num="0022"> Further, the photocatalytic composite film of the present invention has a strong photocatalytic action, and also has a photocatalytic action by room light. In addition, it exhibits a photochemically active catalytic function when irradiated with light, produces active oxygen, has self-purifying activity, antibacterial, antifungal, and antiviral activity, and also exhibits deodorizing activity and formaldehyde decomposition activity.</p><p num="0023"> Furthermore, the photocatalyst composite film of the present invention can be formed by producing the undercoat liquid and the photocatalyst liquid with water as the base material and below the boiling point of water, and sequentially applying and drying the undercoat liquid and the photocatalyst liquid. Therefore, it has a feature that it is easy to manufacture.</p>

<figref num="1">It is a schematic cross-sectional view of the photocatalyst composite film of the present invention, (a) is a view immediately after application of the photocatalyst composite film, and (b) is a state in which a part of the convex portion of the photocatalyst composite film is worn and peeled off. It is a figure which shows.</figref><figref num="2">It is a top view which shows the state of FIG. 1 (b).</figref>

In the process of testing the durability of the prototype, the inventor stated that even if the photocatalyst-covered prototype has insufficient strength and adhesion during test development, the photocatalyst layer applied on the substrate having a rough surface may be used. We found that it has significantly better wear resistance than the photocatalyst layer applied to a smooth surface, and inspired by this, we made a prototype photocatalyst composite film having an undercoat layer with a rough surface, and found that it was more than expected. The present invention has been completed by finding that it has an effect of increasing wear resistance.

FIG. 1 is a schematic cross-sectional view of the photocatalyst composite film of the present invention, (a) is a view immediately after application of the photocatalyst composite film, and (b) is a part of a convex portion of the photocatalyst composite film worn and peeled off. FIG. 2 is a plan view showing the state of FIG. 1 (b). As shown in FIG. 1A, the photocatalyst composite film 10 of the present invention is formed by applying and drying the undercoat layer 2 containing the reinforcing particles 3 on the base material 6, and then applying and drying the photocatalyst layer 1. To.

As the wear of the photocatalyst composite film 10 progressed, as shown in FIG. 1 (b), a part of the photocatalyst layer 1 at the top of the convex portion 4 was worn, the undercoat layer 2 was exposed, and the exposed portion 7 was formed. It becomes a photocatalyst composite film 20. However, as shown in FIG. 2, since the ratio of the area of the exposed portion 7 of the photocatalyst composite membrane 20 is small and the active oxygen diffuses and moves, it is estimated that the contaminants of the exposed portion 7 can also be decomposed. To.

When the applicant is in the state shown in Fig. 1 (b), the hard particles and<u style="single">Peroxotitanic acid</u>Since the convex portion 4 formed from the convex portion 4 protects the anatase-type titanium oxide in the concave portion 5, it is presumed that the progress of wear of the photocatalytic composite film 20 is delayed further, and the reinforcing particles 3 are added to the undercoat layer 2. The present invention was completed with the idea of forming a rough surface in the undercoat layer 2 by blending. Normally, in order to form an undercoat layer having a rough surface, it is necessary to add one new step, but in the case of the present invention, the undercoat layer 2 is already provided and only the reinforcing particles 3 are added. Since it is good, it has the advantage that it does not require an increase in the number of steps.

Hereinafter, the photocatalytic composite film according to the embodiment of the present invention and the method for producing the same will be described. The photocatalytic composite film 10 of the present invention<u style="single">Peroxotitanic acid</u>It also has an undercoat layer 2 containing the reinforcing particles 3 and a photocatalyst layer 1 containing anatase-type titanium oxide coated on the undercoat layer 2.

The reinforcing particles 3 used in the present invention have an average particle diameter (JIS Z 8901: 2006 3.1) of 5 to 500 μm, a Mohs hardness of 5 or more, and can form a rough surface on the undercoat layer 2. Any particle can be used. As an example of the reinforcing particles that can be preferably used, one or more of natural minerals including feldspar and silica stone, silica gel, alumina, or an inorganic powder containing titania can be exemplified, but the reinforcing particles of the present invention include this. It is not limited to. The shape of the reinforcing particles is not particularly limited as long as it can form a rough surface on the undercoat layer 2, and particles having any shape can be used.

The size of the reinforcing particles 3 preferably has an average particle diameter in the range of 5 to 500 μm, more preferably 10 to 300 μm, and most preferably 15 to 200 μm. Particles with an average particle size of less than 5 μm cannot sufficiently protect the photocatalyst layer 1 because the size of the convex portion 4 formed is too small, and particles with an average particle size of more than 500 μm are undercoat layer 2 This makes it difficult to adhere to the base material 6, and the reinforcing particles 3 may peel off. The content of the reinforcing particles 3 forms the undercoat layer 2.<u style="single">Mass of peroxotitanic acid converted to titanium oxide</u>When is 100 parts by mass, the mass of the reinforcing particles 3 is preferably 1 to 100 parts by mass, more preferably 2 to 50 parts by mass, and most preferably 5 to 20 parts by mass. If the mass of the reinforcing particles 3 is less than 1 part by mass, a sufficient convex portion 4 cannot be formed, and if it exceeds 100 parts by mass, the area of the concave portion to be protected becomes small, which is not preferable.

Since the photocatalytic composite film of the present invention is a thin film formed on a rough surface, it is difficult to actually measure the film thickness and the coating amount of the coating film. Therefore, in the embodiment of the present invention, the coating amount is titanium oxide (TiO) coated on the base material having a unit area.₂, Calculated as molar mass 80) or the mass of peroxotitanic acid converted to the mass of titanium oxide (hereinafter referred to as "converted TiO"₂It shall be calculated based on (denoted as "mass").

Of the undercoat layer 2 of the present invention<u style="single">Peroxotitanic acid conversion TiO</u>_{<u style="single">2</u>}The coating amount is 0.1 ~ 100g / m²It is preferably 0.2 to 50 g / m.²Is more preferable, 0.5 to 20 g / m²Is most preferable. The undercoat layer 2 said<u style="single">Peroxotitanic acid conversion TiO</u>_{<u style="single">2</u>}The coating amount is 0.1 g / m²If it is less than 100 g / m, sufficient adhesion and / or shielding function of active oxygen cannot be exhibited.²Even if it is made thicker than the above, it is not economically preferable because no further increase in adhesion and / or shielding function of active oxygen is observed.

The coating amount of the photocatalyst layer 1 of the present invention is 0.1 to 50 g / m as titanium oxide.²It is preferably 0.2 to 20 g / m.²Is more preferable, 1 to 10 g / m²Is most preferable. The coating amount of the photocatalyst layer 1 is 0.1 g / m²If it is less than, it may not be possible to exhibit sufficient photocatalytic activity, and it may be easily worn. The coating amount of the photocatalyst layer 1 is 50 g / m²Even if it is applied in excess of, the increase in photocatalytic activity and strength is small, which is not economically preferable.

Further, according to another embodiment of the present invention, the photocatalyst layer 1 is further covered.<u style="single">Peroxotitanic acid</u>Can be added to increase the strength of the photocatalytic composite film 10. The coating amount of the photocatalyst layer 1 in the other examples is<u style="single">Peroxotitanic acid conversion TiO</u>_{<u style="single">2</u>}0.1 ~ 50g / m when combined with the mass and the mass of anatase-type titanium oxide²It is preferably 0.2 to 20 g / m.²Is more preferable, 1 to 10 g / m²Is most preferable. The total coating amount of titanium oxide is 0.1 g / m²If it is less than 50 g / m, sufficient photocatalytic activity cannot be exhibited and it may be easily worn.²Even if it exceeds the above, the increase in photocatalytic activity and intensity is small, which is economically unfavorable. In addition, the mass of anatase-type titanium oxide contained in the photocatalytic solution and<u style="single">Peroxotitanic acid conversion TiO</u>_{<u style="single">2</u>}<u style="single">mass</u>The mass ratio with and is preferably in the range of 1: 0 to 1: 2 (excluding 0), more preferably 4: 1 to 2: 3, and 3: 2 to 1: 1. Is most preferable. For anatase-type titanium oxide<u style="single">Peroxotitanic acid conversion TiO</u>_{<u style="single">2</u>}<u style="single">mass</u>If the mass ratio with and to exceeds 1: 2, the photocatalytic activity of the photocatalytic composite film decreases, which is not preferable.

When the product of the present invention is applied to a glossy outer wall surface, the product of the present invention does not substantially absorb visible light. Therefore, when the average particle diameter of the reinforcing particles 3 contained in the undercoat layer is small, the outside The gloss of the base material applied to the wall surface is not impaired, and as the average particle size of the reinforcing particles 3 increases, it has a matting effect due to diffused reflection.

(Production method) Hereinafter, a method for producing a photocatalytic membrane composite membrane according to an embodiment of the present invention will be described. The photocatalytic composite film 10 of the present invention includes a peroxotitanic acid aqueous solution manufacturing step for producing a peroxotitanium aqueous solution from a titanium raw material, an undercoating liquid manufacturing step for producing an undercoating solution containing the peroxotitanium aqueous solution and the strengthening particles 3. An undercoat layer forming step in which an undercoat solution is applied to the surface of the substrate 6 and dried to form an undercoat layer 2, and a photocatalyst for producing a photocatalyst solution containing an anatase-type titanium oxide dispersion by heating a peroxotitanium aqueous solution. It can have a liquid manufacturing step and a photocatalyst layer forming step of applying a photocatalyst liquid on the undercoat layer 2 and drying it to form a photocatalyst layer 1. When the photocatalyst membrane composite membrane is used in a very harsh environment, as shown in other examples of the present invention, in the photocatalyst layer forming step, anatase-type titanium oxide dispersion is further added with an aqueous peroxotitanate solution. Can be added to further strengthen the photocatalyst layer 1.

(Peroxotitanic acid aqueous solution manufacturing process) The peroxotitanic acid aqueous solution used for producing the undercoat layer in the present invention can be produced by any method as long as it does not interfere with the implementation of the present invention. For example, as described in Patent Document 1, an aqueous solution containing a titanium raw material is neutralized by adding a hydrogen peroxide solution in excess of the reaction equivalent, and then adding ammonia water, and the obtained yellow solution is left to stand. When the peroxotitanate is precipitated, the precipitate is collected and washed, suspended in water and a hydrogen peroxide solution is added, a yellow transparent peroxotitanate aqueous solution is obtained. The solid obtained by applying an aqueous solution of peroxotitanate and drying it<u style="single">, Pe</u>Has a luoxo group<u style="single">Peroxotitanic acid</u>Is.

Further, as described in Patent Document 2, when a hydrogen peroxide solution is added to a titanium hydroxide gel generated by adding an alkaline component to an aqueous solution containing a titanium raw material and reacted overnight, peroxotitanium, a yellow viscous liquid, is reacted. An aqueous acid solution is obtained. The titanium hydroxide gel used here is preferably washed thoroughly with water until the substance used for precipitation formation is no longer detected. If the substance used for forming the precipitate of the titanium hydroxide gel remains in the titanium hydroxide gel, the produced peroxotitanic acid aqueous solution and the anatase-type titanium oxide dispersion will aggregate, and the particle size of the produced titanium oxide particles will be large. As a result, the adhesion or density of the anatase-type titanium oxide dispersion may decrease.

The amount of peroxotitanic acid contained in the peroxotitanate aqueous solution is "converted" of peroxotitanate when the mass of the peroxotitanate aqueous solution is 100 parts by mass.<u style="single">T</u>iO₂The "mass" is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass. "Conversion<u style="single">T</u>iO₂If the "mass" is less than 0.1 parts by mass, it may not be possible to form an undercoat layer of sufficient thickness, and if it exceeds 20 parts by mass, the viscosity of the peroxotitanic acid aqueous solution increases. It may be difficult to handle.

(Undercoat liquid manufacturing process) An undercoat solution is produced by adding reinforcing particles 3 having an average particle size of 5 to 500 μm and a Mohs hardness of 5 or more to an aqueous solution of peroxotitanic acid. The amount of strengthening particles 3 contained in the undercoat liquid is that of the peroxotitanic acid aqueous solution.<u style="single">"Conversion TiO</u>_{<u style="single">2</u>}<u style="single">mass"</u>When is 100 parts by mass, it is preferably 0.01 to 20 parts by mass, and more preferably 0.02 to 10 parts by mass. If the content of the reinforcing particles 3 is less than 0.01 parts by mass, a surface having sufficient roughness cannot be formed in the undercoat layer 2, and if it exceeds 20 parts by mass, the undercoat liquid flows. The properties may be reduced to make it difficult to apply, or / and the content of the reinforcing particles 3 may be too high to reduce the strength of the undercoat layer 2.

(Undercoat layer forming process) A predetermined amount of the undercoat liquid is applied to form an undercoat layer. The method of applying the undercoat liquid may be any method as long as it meets the object of the present invention, and may be applied at one time or may be applied repeatedly in a plurality of times. Further, the drying temperature is preferably 40 ° C or lower because peroxotitanic acid may gradually change to anatase-type crystals and the strength and adhesion may decrease at 70 ° C or higher.

The amount of undercoat liquid applied is the "converted amount" of peroxotitanic acid contained in the undercoat liquid.<u style="single">T</u>iO₂"Mass" is 0.1 ~ 500g / m²It is preferable to apply so that "Conversion<u style="single">T</u>iO₂"Mass" is 0.1g / m²If it is less than, the undercoat layer 2 having a sufficient thickness cannot be formed, the adhesive force with the photocatalyst layer 1 cannot be sufficiently strengthened, and the undercoat layer 2 is generated by the photocatalyst.<u style="single">Base material from active oxygen 6</u>May not be sufficiently blocked. Also, "Conversion<u style="single">T</u>iO₂"Mass" is 500g / m²Even if an amount exceeding the above amount is applied, the increase in effect is small compared to the increase in cost and labor required for application, which is not preferable.

(Photocatalytic solution manufacturing process) Peroxotitanate aqueous solution at 70 ° C to 200 ° C for 0.2 to 40 hours, preferably 80 to 120 ° C for 1 to 30 hours, most preferably 90 ° C to less than 100 ° C for 1 to 20 hours. A photocatalytic solution containing an anatase-type titanium oxide dispersion can be produced by heat treatment. If the heating temperature is less than 70 ° C, the reaction takes too long, which is not preferable. Even if it is heated above 200 ° C, the reaction will be too fast and control will be difficult, and a high-pressure kettle will be required, which may result in a large-scale device and no effect commensurate with it. ..

The anatase-type titanium oxide concentration of the photocatalyst solution is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, when the mass of the photocatalyst solution is 100 parts by mass. .. If the mass of titanium oxide is less than 0.1 parts by mass, it becomes difficult to form a photocatalyst film of sufficient thickness, and if it exceeds 20 parts by mass, the viscosity of anatase-type titanium oxide may increase, making handling difficult. is there. The X-ray diffraction spectrum of the film formed by applying a heat-treated solution of a peroxotitanic acid aqueous solution and solidifying it has a peak based on anatase-type titanium oxide, as described in Patent Documents 1 and 2. Have.

(Photocatalyst layer forming process) A photocatalyst solution is applied on the undercoat layer and dried to form a photocatalyst layer. The coating method may be any method as long as it meets the object of the present invention. The application can be performed once or divided into multiple times. The drying method is not particularly limited, but it is preferably performed at 60 ° C. or lower. The amount of anatase-type titanium oxide applied to the photocatalyst layer 1 of the present invention is 0.1 to 250 g / m.²Is preferable. The coating amount of the photocatalyst layer 1 is 0.1 g / m²If it is less than 250 g / m, a photocatalyst layer with sufficient thickness may not be formed.²Even if it is applied in excess of, the increase in photocatalytic activity and strength is small compared to the increase in cost and labor required for application, which is not preferable.

Further, according to another embodiment of the present invention, the photocatalyst layer 1 is further added.<u style="single">Peroxotitanic acid</u>Can be included. In the photocatalyst container of another embodiment, when the mass of the photocatalyst solution is 100 parts by mass, the mass of anatase-type titanium oxide and the "conversion of peroxotitanic acid"<u style="single">T</u>iO₂The total mass of "mass" is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 5 parts by mass. If the total mass is less than 0.1 parts by mass, it may not be possible to form an undercoat layer of sufficient thickness, and if it exceeds 20 parts by mass, the viscosity of the photocatalyst solution increases and it is handled. Can be difficult.

The coating amount of the catalyst layer 1 in the other embodiment is "converted total".<u style="single">T</u>iO₂"Mass" When the mass of peroxotitanic acid is converted to the mass of titanium oxide and added to the mass of anatase-type titanium oxide, the dispersion amount is 0.1 to 250 g / m.²Is preferable. Dispersion amount is 0.1 g / m²If it is less than 250 g / m, a photocatalyst layer with sufficient thickness may not be formed.²Even if it is applied in excess of, the increase in photocatalytic activity and strength is small compared to the increase in cost and labor required for application, which is not preferable. In addition, the mass of anatase-type titanium oxide contained in the photocatalytic solution and the "conversion" of peroxotitanic acid.<u style="single">T</u>iO₂The ratio of "mass" to is preferably in the range of 1: 0 to 1: 2, more preferably 4: 1 to 2: 3, and most preferably 3: 2 to 1: 1. ..

(Example) Hereinafter, the present invention will be described in detail with reference to Examples. (Example 1) [First step] Manufacture of undercoat liquid Titanium hydroxide was precipitated by dropping 2.5% (mass / volume) aqueous ammonia and 440 ml into a solution prepared by adding 39.6 ml of a 60% (mass / volume) aqueous solution of titanium tetrachloride to 4000 ml of distilled water. The precipitate was collected by filtration, washed with distilled water, and then 30% (mass / volume) hydrogen peroxide solution and 80 ml were added to a 720 ml titanium hydroxide suspension to which distilled water was added, and the mixture was stirred. Leave at 7 ° C for 24 hours to decompose excess hydrogen peroxide solution<u style="single">Se</u>After that, water was added to obtain 1.00 kg of a peroxotitanic acid aqueous solution of a yellow viscous liquid. "Conversion of peroxotitanic acid" in 100 parts by mass of peroxotitanic acid aqueous solution<u style="single">TiO</u>_{<u style="single">2</u>}"Mass" is 1.00 parts by mass. To 100 parts by mass of this peroxotitanic acid aqueous solution, 0.1 part by mass of a silica stone powder having an average particle diameter of 20 μm was added, and the mixture was stirred to obtain an undercoat liquid.

[Second step] Manufacturing process of undercoat layer 20 g / m on melamine decorative plywood using a spray spray while stirring the undercoat liquid produced in the first step.²An undercoat layer having a rough surface was produced by applying in an amount of 2 and drying at 25 ° C. "Conversion" of peroxotitanic acid in the undercoat layer<u style="single">TiO</u>₂When "mass" was 100 parts by mass, the mass of silica stone was 10 parts by mass.

[Third step] Manufacturing process of photocatalytic solution The peroxotitanate aqueous solution obtained in the first step was sealed in a pressure-resistant glass container and boiled in a water bath for 12 hours (98 to 100 ° C.) to obtain a pale yellow translucent photocatalytic solution. When the mass of the photocatalyst solution was 100 parts by mass, the mass of anatase-type titanium oxide was 1.0 part by mass.

[Fourth step] Photocatalytic composite film manufacturing process 100 g / m of the photocatalytic solution produced in the third step on the undercoat layer obtained in the second step.²The sample of Example 1 coated with the photocatalyst composite film containing the anatase-type titanium oxide of Example 1 was obtained by applying the amount of the above and drying at 40 ° C. The amount of anatase-type titanium oxide applied to the photocatalytic layer of the produced sample is 1.0 g / m.²Is.

(Example 2) Similar to Example 1, however, in the fourth step, the undercoat liquid obtained in the first step of Example 1 and the photocatalyst liquid obtained in the third step are 1: 1 (mass, mass of reinforcing particles 3). Was ignored because it was a small amount), coated on the undercoat obtained in the second step, and dried to produce the photocatalytic composite film of Example 2.

(Comparative example 1) Similar to Example 1, however, the photocatalytic composite film of Comparative Example 1 having no rough surface was produced without adding reinforcing particles to the undercoat layer. (Comparative example 2) Similar to Example 2, however, the undercoat layer is not added with reinforcing particles, and the photocatalyst layer has no rough surface.<u style="single">Peroxotitanic acid</u>A photocatalytic composite film of Comparative Example 2 containing the above was produced.

(Comparative example 3) 10ml / m on melamine decorative plywood²Only the photocatalytic solution of No. 1 was applied and dried. (Comparative example 4) Only the undercoat liquid was applied and dried on the melamine decorative plywood to form an undercoat layer.

[Abrasion resistance test] (Manufacturing of test pieces) Using a melamine resin decorative plywood having a thickness of 1.5 mm as a base material, a red photocatalyst layer was produced in the same manner as in Example 1 by adding 0.01 parts by mass of red dye to 100 parts by mass of the photocatalyst solution in the second step. After coating and drying, it was punched out with a circular punching machine and subjected to an abrasion resistance test. (Measurement of wear resistance) Abrasion resistance test was conducted in accordance with JIS K 5600 (wear wheel method), but the coating film was too thin to measure the exact amount of change in mass.<u style="single">By the way</u>Therefore, the number of rotations of the wear wheel until the red photocatalyst layer powder discharged from the scanning portion of the wear wheel was not visually red was measured. The test was performed 10 times, the arithmetic mean of the measured values was performed, and the 1st place was rounded off.

(Test Example 1) Nitric oxide removal test In the present specification, the photocatalytic function was measured using the action of removing nitric oxide. The samples prepared in Examples 1 and 2 and Comparative Examples 1 to 4 were subjected to a nitric oxide removal test in accordance with JIS R 1701-1: 2004, Fine Ceramics-Photocatalytic Material.

Abrasion resistance test and nitric oxide removal test were carried out for Examples 1 and 2 and Comparative Examples 1 to 4. The results are shown in Table 1.<tables num="1"><img id="000002" he="57" wi="159" file="JP6067825B1_D0001.tif" img-format="tif" img-content="drawing" /></tables>

As shown in Example 1 of Table 1, the photocatalytic composite film of the first embodiment of the present invention is a photocatalytic composite film containing the conventional photocatalytic composite film shown in Comparative Example 1 and the non-crystalline titanium oxide shown in Comparative Example 2. It showed stronger wear resistance and a photocatalytic function (NO removing action) equivalent to that of Comparative Example 1. The photocatalytic composite film shown in Comparative Example 2 showed a decrease in photocatalytic function. The photocatalytic composite film of another embodiment of the present invention shown in Example 2 of Table 1 showed stronger wear resistance than the photocatalytic composite film of Example 1, but the photocatalytic activity indicated by the amount of NO removed was It was inferior to the photocatalytic composite film of Example 1. However, under harsh conditions where higher strength is required, the composite photocatalyst membrane of Example 2 also has sufficient performance to withstand practical use.

[Examination of average particle size of strengthened particles] (Examples 3 to 6) Similar to Example 1, however, as shown in Table 2, the photocatalytic composite films of Examples 4 to 6 were produced by changing the average particle size of silica stone contained in the undercoat layer. (Comparative Examples 5 and 6) Similar to Example 1, however, as shown in Table 2, the photocatalytic composite films of Comparative Examples 5 and 6 were produced by changing the average particle size of silica stone contained in the undercoat layer.

Abrasion resistance test and nitric oxide removal test were carried out for Examples 1 and 3 to 6 and Comparative Examples 5 and 6. The results are shown in Table 2.<tables num="2"><img id="000003" he="67" wi="141" file="JP6067825B1_D0001.tif" img-format="tif" img-content="drawing" /></tables>

As shown in Table 2, when the average particle diameter of the reinforcing particles is 1 μm as in Comparative Example 2, the wear resistance cannot be sufficiently enhanced, but as shown in Examples 3 to 6, the average particles of the reinforcing particles are average particles. If the diameter is 5 to 500 μm, it shows a significant wear resistance strengthening effect. When the particle size of the reinforcing particles was 1000 μm, the reinforcing particles were missing and the wear resistance was lowered.

[Examination of the amount of strengthened particles] (Examples 7 to 9) Similar to Example 1, however, as shown in Table 3, the amount of silica stone contained in the undercoat layer was changed to produce the photocatalytic composite films of Examples 7 to 9. (Comparative example 7.8) Similar to Example 1, however, as shown in Table 3, the photocatalytic composite films of Comparative Examples 7 and 8 were produced by changing the amount of silica stone contained in the undercoat layer.

Abrasion resistance test and nitric oxide removal test were carried out for Examples 7 to 9 and Comparative Examples 7 and 8. The results are shown in Table 3.<tables num="3"><img id="000004" he="60" wi="142" file="JP6067825B1_D0001.tif" img-format="tif" img-content="drawing" /></tables>

As shown in Table 3, when the mass of the undercoat layer is 100 parts by mass, when the mass of the reinforcing particles is 0.5 parts by mass or less, a sufficient strengthening action of wear resistance is not observed, but Examples 7 to 9 show. When 1 to 100 parts by mass or more of the reinforcing particles are added as shown in the above, a significant strengthening effect of wear resistance is observed. However, when the amount of the reinforcing particles was 200 parts by mass or more, the reinforcing particles were not sufficiently fixed, and the wear resistance test could not be performed. Even at 100 parts by mass, large reinforcing particles cannot be sufficiently fixed, but it is judged that they can be used when there are few voids due to a collection of reinforcing particles having a small average particle size or a collection of reinforcing particles having large and small particle diameters.

1 Photocatalytic layer 2 Undercoat layer 3 Reinforced particles 4 recess 5 convex part 6 Base material 7 Exposed part 10 Photocatalytic composite membrane 20 Photocatalytic composite film (partial wear)