JP2005041117A - Photocatalyst sheet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel photocatalyst sheet characterized in that mutual base materials coated with a fluoroplastic are easily joined under heating and having high anti-staining properties, and its manufacturing method. <P>SOLUTION: The photocatalyst sheet 1 is composed of a base material 2, the first fluoroplastic layer 3 applied to the base material 2, the second fluoroplastic layer 4 applied on the first fluoroplastic layer 3 and the third fluoroplastic layer 5 containing a photocatalyst applied on the second fluoroplastic layer 4. The melting point of the first fluoroplastic layer 2 may be made higher than the melting points of the second and third fluoroplastic layers 4 and 5. Anti-staining properties can be imparted to the photocatalyst sheet 1 without obstructing the thermal joining properties of a conventional sheet and this photocatalyst sheet 1 can be used over a long period of time without damaging the fine view of the hue applied to the sheet. The photocatalyst sheet having a large area for a film structure building can be manufactured at a low cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photocatalyst sheet whose outermost surface is coated with a fluororesin containing a photocatalyst and a method for producing the same.

Domes such as baseball stadiums and event halls, soccer stadiums, tent warehouses, gymnasiums, commercial structures, membrane structures such as eaves tents, track hoods, curing sheets, rainproof clothing, bags, In order to ensure translucency and antifouling properties, the base material of fiber reinforced resin for machinery such as waterproof cloth used for chairs, belt conveyors, timing belts, etc. is almost transparent or colorless and transparent surface treatment agent. It is covered. In addition, in this specification, a base material is a concept including the above-mentioned various products themselves or materials used in these products, and is a state in which the surface of the material (raw material) is coated with a surface treatment agent or a state before coating. It is used as a concept including things.
Conventionally, a surface film according to the purpose such as antifouling, durability improvement and bonding is formed on the surface of the base material. In order not to impair the light transmission performance and to ensure antifouling properties, a surface film that is almost transparent or colorless and transparent has been used. As the film structure material, for example, a film structure material in which a fiber cloth made of glass fiber or the like is used as a base material and the base material is covered with a fluororesin layer is known. This membrane structure material has the advantages that it is nonflammable, has high mechanical strength, and is light and flexible. However, a membrane structure material coated with a fluororesin layer has a problem that substances such as fine smoke such as smoke, dust, and yellow sand in the atmosphere adhere to the membrane surface and become dirty.

In recent years, the photocatalyst is coated on the surface of various materials such as a glass substrate. When the photocatalyst is irradiated with ultraviolet rays contained in sunlight, the photocatalyst is being used for so-called antifouling, in which the redox reaction of the photocatalyst is used to decompose dirt due to organic substances adhering to the surface of the material.
As a method for attaching a photocatalyst to a glass substrate, there is a method using a binder (binder) containing a photocatalyst. For example, a composition in which a non-oxidizing polymer material and titanium oxide fine particles serving as a binder are mixed in a solvent. It is known (see Patent Document 1). In this document, non-oxidizing polymers such as silicone resins, porous materials such as alumina and silica, colloidal tin oxide, and mixtures of these materials are used as binders. This binder can be applied to the surface of the material only by drying or low-temperature heating (cure), even for materials that require a heat treatment to be coated by heat treatment (sinter) by heating, such as conventional plastics and fibers. Although it is disclosed that it can be coated, a method for coating a fluororesin layer containing a photocatalyst on the fluororesin layer is not disclosed.

  As a method for coating a fluororesin layer containing a photocatalyst on a substrate, Patent Documents 2 and 3 disclose a disperser containing photocatalytic titanium oxide fine particles on a PTFE layer (polytetrafluoroethylene) which is a fluororesin. It is disclosed that a PTFE layer in which photocatalytic titanium oxide fine particles are exposed is formed by repeating the steps of applying John (dispersing agent), drying and baking.

  In Patent Documents 4 and 5, a photocatalyst layer is formed by applying and baking a dispersion containing PTFE powder and photocatalyst fine particles on a reinforcing layer of a membrane structure material or a PTFE layer as a support. It is disclosed.

US Pat. No. 5,616,532 JP 09-207289 A (page 3-4, FIG. 1) JP 10-44346 A (page 5-6, FIG. 1) Japanese Patent Laid-Open No. 11-47610 (page 3-4, FIG. 1) Japanese Patent Laid-Open No. 11-47612 (page 2-3, FIG. 1)

When the membrane structure has a large area, it is assembled using a large number of membrane structure substrates. In this case, in order to prevent water leakage or air leakage to the membrane structure, it is necessary to join the membrane structure substrates together. Conventionally, in the case of a base material whose surface is coated with a fluororesin, the same fluororesin tape having a width wider than the overlapped portion is thermally welded so that the thermal bonding between the base materials for the membrane structure can be performed. I was going.
However, in the case of a base material whose surface is coated with a fluororesin, the base materials can be thermally bonded to each other, but the surface of the fluororesin is easily contaminated, and the cleaning is performed on a large-scale membrane structure such as an outdoor stadium. In a thing, there exists a subject that the cost required for washing | cleaning is high.

  On the other hand, in the photocatalyst sheet containing the photocatalyst in the fluororesin layer, if the fluororesin layer contains an inorganic substance that becomes a photocatalyst such as titanium oxide, thermal bonding becomes difficult, and thermal bondability and antifouling property at the thermal bond portion There is a problem that a photocatalyst sheet excellent in the above has not yet been realized.

  In view of the above-mentioned problems, the present invention can easily perform thermal bonding between substrates coated with a fluororesin by coating a fluororesin containing a photocatalyst on the outermost surface of the membrane structure, and has a high antifouling property. An object of the present invention is to provide a novel photocatalytic sheet and a method for producing the same.

In order to achieve the above object, a first configuration of the photocatalyst sheet of the present invention includes a base material, a first fluororesin layer coated on the base material, and a first fluororesin layer coated on the first fluororesin layer. And a third fluororesin layer containing a photocatalyst coated on the second fluororesin layer.
The second configuration of the photocatalyst sheet of the present invention includes a base material, a first fluororesin layer coated on the base material, and a second photocatalyst coated on the first fluororesin layer. It is characterized by comprising a fluororesin layer and a third fluororesin layer containing a photocatalyst coated on the second fluororesin layer.
In any of the above configurations, the antifouling property of the fluororesin surface can be enhanced by the photocatalyst exposed on the surface of the uppermost layer of the photocatalyst sheet.

In the above configuration, the base material is made of fibers, and the surface shape thereof may be flat, uneven uneven surface, or mesh.
Preferably, the fiber is glass fiber, the first fluororesin layer is PTFE, the second fluororesin layer is FEP or PFA, and the third fluororesin layer is made of FEP. Alternatively, the substrate is glass fiber, the first fluororesin layer is PTFE, the second fluororesin layer is any one of PTFE, FEP, and PFA, and the third fluororesin layer is It may consist of FEP.
According to the above configuration, since the FEP of the uppermost fluororesin layer containing the photocatalyst formed on the substrate made of glass fiber has a lower melting point than PTFE that is the first fluororesin layer on the substrate side, the photocatalyst sheet Highly antifouling can be achieved by the oxidation-reduction reaction when the photocatalyst exposed on the surface of the third fluororesin of the photocatalyst sheet is irradiated with ultraviolet rays contained in sunlight. Is granted.

According to the present invention, in the above configuration, the melting point of the first fluororesin layer is higher than the melting points of the second fluororesin layer and the third fluororesin layer, and the melting point of the second fluororesin layer is the third fluororesin. It is characterized by being equal to or higher than the melting point of the layer. The second fluororesin layer and the third fluororesin layer may be the same fluororesin.
In the present invention, the melting point of the first fluororesin layer is higher than the melting points of the second fluororesin layer and the third fluororesin layer, and the melting point of the first fluororesin layer is the melting point of the second fluororesin layer. Same or higher than The first fluororesin layer and the second fluororesin layer may be made of the same fluororesin. Alternatively, the first fluororesin layer and the third fluororesin layer may be made of the same fluororesin.
In the present invention, the melting point of the third fluororesin layer is higher than the melting points of the first fluororesin layer and the second fluororesin layer, and the melting point of the second fluororesin layer is the melting point of the first fluororesin layer. Same or higher than The first fluororesin layer and the second fluororesin layer may be made of the same fluororesin.
In the present invention, the melting point of the third fluororesin layer is higher than the melting points of the first fluororesin layer and the second fluororesin layer, and the melting point of the third fluororesin layer is that of the second fluororesin layer. It is the same as or higher than the melting point. The third fluororesin layer and the second fluororesin layer may be made of the same fluororesin.
According to the said structure, the combination of the 1st-3rd fluororesin layer which makes the heat joining characteristic of photocatalyst sheets favorable can be obtained easily.

In the above structure, the photocatalyst is characterized by comprising at least titanium oxide (TiO ₂ , TiO ₃ ). This photocatalyst has a portion exposed on the third fluororesin layer. It is preferable that the weight% in the 3rd fluororesin layer of a photocatalyst is 10 to 60 weight%.
According to the above configuration, a photocatalyst sheet using at least titanium oxide is obtained, and a photocatalyst sheet that is easy to thermally bond between photocatalyst sheets and has high antifouling properties is obtained.

The method for producing a photocatalytic sheet of the present invention includes a step of coating a first fluororesin layer on a substrate, a step of coating a second fluororesin layer on the first fluororesin layer, and a second fluorine And a step of coating a third fluororesin layer containing a photocatalyst on the resin layer. Moreover, the manufacturing method of the photocatalyst sheet of this invention coat | covers the 2nd fluororesin layer which made the process coat | cover the 1st fluororesin layer on a base material, and contained the photocatalyst on the 1st fluororesin layer. And a step of coating a third fluororesin layer containing a photocatalyst on the second fluororesin layer.
According to the above production method, the outermost surface of the base material is covered with the fluororesin layer containing a photocatalyst, thereby making it possible to obtain a photocatalyst sheet that can be easily bonded by heat and has antifouling properties. it can.

  In the above configuration, a coating that forms the first fluororesin layer, the second fluororesin layer containing the second fluororesin layer or the photocatalyst, and the third fluororesin layer containing the photocatalyst The steps are preferably performed continuously. According to this structure, the photocatalyst sheet | seat which made the 3rd fluororesin layer which continuously coat | covered the 1st-3rd fluororesin layer on the base material and made the uppermost layer contain the photocatalyst efficiently is manufactured. can do.

  Further, in the above configuration, a step of covering the base material previously coated with the first fluororesin layer and the second fluororesin layer with the third fluororesin layer containing the photocatalyst may be performed. According to this structure, after manufacturing the base material previously coated with the first fluororesin layer and the second fluororesin layer, the third fluororesin layer containing the photocatalyst can be coated at any time. A photocatalytic sheet can be produced.

  A third fluororesin layer containing a photocatalyst, a step of applying a fluororesin dispersant containing titanium oxide fine particles to be a photocatalyst onto the second fluororesin layer, a step of drying, And a step of exposing the photocatalyst to the surface of the third fluororesin layer while being sintered at a temperature higher than the melting point of the fluororesin used for the third fluororesin layer. According to this structure, the 3rd fluororesin layer containing a photocatalyst can be sintered to the 1st and 2nd fluororesin layer on a base material, and a photocatalyst sheet with a favorable thermal joining characteristic and antifouling property is manufactured. can do.

  According to the photocatalyst sheet of the present invention, antifouling properties can be imparted without impairing the thermal bondability of a conventional sheet having a fluororesin layer as the uppermost layer. Therefore, if the photocatalyst sheet of the present invention is used for a membrane structure or the like instead of the conventional sheet, the sheets can be thermally bonded to each other and have antifouling property, so that the aesthetic appearance of coloring applied to the sheet is impaired. And can be used for a long time.

  Moreover, according to the method for producing a photocatalyst sheet of the present invention, a photocatalyst sheet having high antifouling properties can be produced at low cost, with which the photocatalyst sheets can be thermally bonded easily.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The structure of the photocatalytic sheet of the present invention will be described with reference to FIGS. FIG.1 and FIG.2 is sectional drawing which shows typically the structure of the photocatalyst sheet | seat of this invention. As shown in the figure, the photocatalyst sheet 1 of the present invention has a first fluororesin layer 3, a second fluororesin layer 4, and a photocatalyst on both surfaces of a substrate 2 made of glass fiber, fiber reinforced resin, or the like. It has a structure in which the contained third fluororesin layer 5 is sequentially laminated.
In the case of FIG. 1, as an example, a structure in which multilayer fluororesin layers 3, 4, and 5 are coated on both surfaces of the base material 2 is shown. However, as shown in FIG. Of course, the photocatalyst sheet 10 of the present invention may cover the third fluororesin layer 5 containing the photocatalyst only on a predetermined region of one side or the surface of the substrate 2.
The base material 2 is a woven or non-woven fabric made of fibers such as glass fiber, carbon fiber, polyimide fiber, polyimide fiber, PBO fiber, silica fiber, basalt fiber, polyester fiber, nylon fiber, cotton, hemp, kenaf. Here, the surface shape of the base material 2 may be any one of flat, uneven uneven surface, and mesh.

In the first to third fluororesin layers 3, 4, and 5, the melting point of the first fluororesin layer 3 is higher than the melting points of the second fluororesin layer 4 and the third fluororesin layer 5, and the second The melting point of the fluororesin layer 4 may be the same as or higher than the melting point of the third fluororesin layer 5. In this case, the second fluororesin layer 4 and the third fluororesin layer 5 may be made of the same fluororesin. The melting point of the first fluororesin layer 3 is higher than the melting points of the second fluororesin layer 4 and the third fluororesin layer 5, and the melting point of the first fluororesin layer 3 is the second fluororesin layer 4. It may be the same as or higher than the melting point of. In this case, the first fluororesin layer 3 and the second fluororesin layer 4 may be made of the same fluororesin.
Furthermore, the 1st fluororesin layer 3 and the 3rd fluororesin layer 5 may consist of the same fluororesin.
Thereby, the combination of the 1st-3rd fluororesin layer which makes the heat joining characteristic of photocatalyst sheets favorable can be obtained easily.

In the first to third fluororesin layers 3, 4, 5, the melting point of the third fluororesin layer 5 is higher than the melting points of the first fluororesin layer 3 and the second fluororesin layer 4, The melting point of the second fluororesin layer 4 may be the same as or higher than the melting point of the first fluororesin layer 3. In this case, the first fluororesin layer 3 and the second fluororesin layer 4 may be made of the same fluororesin.
The melting point of the third fluororesin layer 5 is higher than the melting points of the first fluororesin layer 3 and the second fluororesin layer 4, and the melting point of the third fluororesin layer 5 is the second fluororesin layer 4. It may be the same as or higher than the melting point of. In this case, the third fluororesin layer 5 and the second fluororesin layer 4 may be made of the same fluororesin.
According to the said structure, the combination of the 1st-3rd fluororesin layer which makes the heat joining characteristic of photocatalyst sheets favorable can be obtained easily.

As fluororesins, polytetrafluoroethylene (PTFE, melting point 327 ° C.), polyvinylidene fluoride (PVDF, melting point 156 to 178 ° C.), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, melting point = 310 ° C.) , A polymer of a monomer containing fluorine such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point = 275 ° C.), or a copolymer can be used. The melting point of each material is described in Japan Fluoropolymer Industry Association, edited by “Fluorine Resin Handbook”, 7th edition, Japan Fluoropolymer Industry Association, June 1998, p. See 18.
As an example, the photocatalytic sheet 1 of the present invention has a base material 2 as glass fiber, the fluororesin layer, a first fluororesin layer 3 as PTFE (melting point T1 = 327 ° C.), and a second fluororesin layer 4 as FEP. FEP (melting point T3 = 275 ° C.) can be used as the third fluororesin layer 5 containing (melting point T2 = 275 ° C.) or PFA (T2 = 310 ° C.) and a photocatalyst.

FIG. 3 is a cross-sectional view schematically showing another structure of the photocatalyst sheet 20 of the present invention. As shown in the figure, the photocatalyst sheet 20 of the present invention is different from the photocatalyst sheet 10 in that the photocatalyst is also contained in the second fluororesin layer 4 ′. The second fluororesin layer 4 ′ can be the same fluororesin layer as the first fluororesin layer or a fluororesin layer having a low melting point. The melting point (T3) of the third fluororesin layer 5 containing the photocatalyst is the same as or lower than the melting point (T2) of the second fluororesin layer 4 ′ containing the photocatalyst, ie, T3 ≦ T2. It is good also as a resin layer. Since other configurations are the same as those of the photocatalyst sheet 10, the description thereof is omitted.
As an example, the photocatalyst sheet 20 of the present invention is made of PTFE as the second fluororesin layer 4 ′ containing the glass fiber, the first fluororesin layer 3 as PTFE (melting point T1 = 327 ° C.), and the photocatalyst as an example. (Melting point T2 = 327 ° C.), FEP (melting point T2 = 275 ° C.), PFA (melting point T2 = 310 ° C.), FEP (melting point T3) as the third fluororesin layer 5 containing a photocatalyst. = 275 ° C.) can be used.
According to this configuration, as will be described later, since the second fluororesin layer 4 ′ also contains a photocatalyst, when the photocatalyst sheets 1 are thermally bonded to each other by sintering (hereinafter also referred to as thermal welding as appropriate), thermal bonding is performed. The antifouling property due to the action of the photocatalyst in the part is not impaired, and the antifouling property can be maintained for a long time.

FIG. 4 is an enlarged cross-sectional view showing the structure on the surface side of the substrate coated with the third fluororesin layer containing the photocatalyst of the present invention. For the third fluororesin layer 5 containing a photocatalyst, for example, a fluororesin such as FEP is used, and photocatalysts 7 and 8 are further added.
Here, the photocatalysts 7 and 8 are photocatalyst fine particles such as anatase type TiO ₂ (titanium dioxide) having a diameter of 1 nm to 100 nm, for example, and the photocatalyst fine particles in the third fluororesin layer 5 and the surface 5a thereof. The exposed photocatalyst fine particles are shown. In order to enhance the photocatalytic effect, it is desirable that the particle diameters of the photocatalysts 7 and 8 are appropriately small in order to increase the surface area of the photocatalyst 8 exposed on the surface 5a.

Here, the photocatalysts 7 and 8 are materials also called optical semiconductors. The photocatalysts 7 and 8 include anatase TiO ₂ (forbidden band width 3.2 eV, wavelength 388 nm), rutile TiO ₂ (forbidden band width 3.0 eV, wavelength 414 nm), titanium trioxide (TiO ₃ ), etc. Can be used. These titanium oxides are collectively referred to as titanium oxide. In addition to titanium oxide, the photocatalyst includes zinc oxide (ZnO, forbidden band width 3.2 eV, wavelength 388 nm), strontium titanate (SrTiO ₂ , forbidden band width 3.2 eV, wavelength 388 nm), tungsten trioxide (WO ₃ , Forbidden band width 3.2 eV, wavelength 388 nm) and the like can be used.
Moreover, the compounding quantity of the photocatalyst contained in the 3rd fluororesin layer 5 containing the said photocatalyst is arbitrary, What is necessary is just to adjust the viscosity of a solution suitably with a use, a performance, and the coating method. When the photocatalyst sheets 1, 10 and 20 are thermally bonded (hereinafter also referred to as heat welding as appropriate), the blending amount of the photocatalyst is a solid concentration in the fluororesin 5 so that the strength of the heat bonded portion does not decrease. The amount of the component is preferably 10 to 60% by weight. Moreover, the surface of the photocatalyst sheet | seat 1,10,20 can be made hydrophobic or hydrophilic by changing the compounding quantity of the photocatalyst contained in the 3rd fluororesin layer 5 containing the photocatalyst of this invention.
In addition, in order to further impart conductivity and a photocatalytic effect enhancement effect to the third fluororesin layer 5 containing the photocatalyst, a metal material or a photocatalytic function auxiliary substance may be added. As the metal material, Ag, Al, Au, Cu, Fe, In, Ir, Ni, Os, Pd, Pt, Rh, Ru, Sb, Sn, Zn, Zr, or the like can be used.

The photocatalyst sheet of the present invention is configured as described above. When the photocatalyst is contained in the uppermost layer, when the photocatalyst sheet is irradiated with ultraviolet rays of about 400 nm or less contained in sunlight or a fluorescent lamp, Due to the oxidation-reduction reaction, the organic matter attached to the photocatalyst sheet is decomposed to give high antifouling properties. In addition, thermal bonding between the photocatalyst sheets can be easily performed.
Thereby, if the photocatalyst sheet | seat of this invention is used for a film structure building, for example, the heat joining of photocatalyst sheets can be easily performed similarly to the sheet | seat which coat | covered the fluororesin to the conventional base material. In addition, after the construction of the structure building, the high antifouling property due to the oxidation-reduction reaction of the photocatalyst such as titanium oxide exposed on the uppermost layer of the photocatalyst sheet does not impair the aesthetic appearance of the color of the sheet for a long period of time.

  Next, the manufacturing method of the photocatalyst sheet of this invention is demonstrated with reference to FIG. FIG. 5 is a flow chart sequentially showing the steps in producing the photocatalytic sheet of the present invention. First, as shown in FIG. 5A, a fluororesin dispersant to be the first fluororesin layer 3 is applied to the base material 2 made of glass fibers by using a dipping coating method. In the present invention, the coating liquid, dispersant, or coating agent used when forming the fluororesin is generically called a dispersant.

  Next, as shown in FIG. 5B, in order to improve the uniformity of the coating film of the fluororesin dispersant, the fluororesin dispersant applied to the substrate is dried. In this drying step, the drying temperature may be about 20 ° C. to 100 ° C., and the drying time may be about 3 to 60 minutes. Depending on the composition of the fluororesin dispersant, the drying step can be performed by natural drying by standing at room temperature or by a forced drying method using wind or a heat source. In the forced drying method, it can be performed with an electric furnace such as resistance heating, a heat source such as infrared or far-infrared heating, and an apparatus that combines a blower.

Next, as shown in FIG. 5C, a sintering process is performed to form the first fluororesin layer 3 on the substrate 2 as a coating. What is necessary is just to set the processing temperature of this sintering process according to melting | fusing point of the 1st fluororesin layer 3 coat | covered with the base material 2. FIG.
Here, by setting the firing temperature higher than the melting point of the first fluororesin, the fluororesin is melted, and there is no gap between the fluororesin powder and the photocatalyst powder. This sintering step may be performed, for example, at a temperature of about 50 ° C. higher than the melting point of the first fluororesin for about 3 minutes to 30 minutes. If the sintering temperature is higher than the melting point of the fluororesin by 50 ° C. or more, the temperature reaches the decomposition temperature of the fluororesin, which may cause decomposition of the fluororesin and accompanying damage to the base material.
After sintering, it is cooled to room temperature by a cooling process. At this point, the base material 2 is covered with a film of the first fluororesin layer 3.
Here, in the cooling step, the first fluororesin layer 3 is made non-crystallized in order to make the coating formed by the dispersant that becomes the first fluororesin layer 3 a dense and tough film without haze. In order to make it cool, it is preferable to quench.
The cooling step can be performed by natural cooling in an atmosphere at room temperature after taking out the substrate 2 coated with the first fluororesin layer 3 after sintering from the electric furnace.
In addition, in order to make the 1st fluororesin layer 3 into a predetermined film thickness, you may perform repeatedly application | coating of a dispersing agent, drying, and a sintering process (FIG. 5 (A) and FIG.5 (C)). See dotted line).

  Next, as shown in FIG. 5 (D), a fluororesin dispersant to be the second fluororesin layer 4 is applied on the first fluororesin layer 3 by using a dipping coating method.

Next, as shown in FIG. 5 (E), in order to improve the uniformity of the coating film of the fluororesin dispersant that becomes the second fluororesin layer 4, the second applied to the first fluororesin layer 3. The fluororesin dispersant that becomes the fluororesin layer 4 is dried.
In this drying step, the drying temperature may be about 20 ° C. to 100 ° C., and the drying time may be about 3 to 60 minutes.

  Next, as shown in FIG. 5F, a sintering process is performed to form the second fluororesin layer 4 as a coating on the first fluororesin layer 3. What is necessary is just to set the processing temperature of this sintering process according to melting | fusing point of the 2nd fluororesin layer 4 coat | covered with the 1st fluororesin layer 3. FIG. After sintering, it is cooled to room temperature by a cooling process. At this point, the first fluororesin layer 3 is covered with the coating film of the second fluororesin layer 4.

  Next, as shown in FIG. 5G, the third fluororesin layer 5 containing a photocatalyst is formed on the second fluororesin layer 4 by using a dipping coating method, for example, an oxidation that becomes a photocatalyst. A fluororesin dispersant containing titanium fine particles is applied.

  And as shown in FIG.5 (H), in order to improve the uniformity of the coating film of the dispersing agent used as the fluororesin layer 5 containing the photocatalyst apply | coated on the 2nd fluororesin layer 4, it is made to dry. . In this drying step, the drying temperature may be about 20 ° C. to 100 ° C., and the drying time may be about 3 to 60 minutes.

Next, as shown in FIG. 5I, a sintering process is performed to form a third fluororesin layer 5 containing a photocatalyst on the second fluororesin layer 4 as a film. What is necessary is just to set the processing temperature of this sintering process according to melting | fusing point of the 3rd fluororesin layer 5 containing the photocatalyst. After sintering, it is cooled to room temperature by a cooling process. At this point, the second fluororesin layer 4 is covered with a film of the third fluororesin layer 5 containing a photocatalyst.
As described above, the photocatalytic sheet of the present invention can be produced.

  Here, the coating method of the dispersant used for each of the fluororesin layers is not only the dipping coating method but also the bar coating method, air spray coating method, gravure coating method, impregnation method, sponge coating method, electrostatic spray method, brush coating method. The method, the flow coat method, the roll coat method, etc. can be used preferably.

  In addition, although said manufacturing process is a method of forming the 1st-3rd fluororesin layer 3, 4, 5 continuously in the base material 2 which consists of glass fibers using a dipping coat method, it is another method. As described above, a base material in which only the first and second fluororesin layers 3 and 4 are formed on the base material 2 made of glass fiber is manufactured first, and then a third fluororesin layer 5 containing a photocatalyst is formed. You may manufacture by the process to coat | cover.

  The photocatalyst sheet of this invention is manufactured as mentioned above, and can manufacture the photocatalyst sheet coat | covered with the 3rd fluororesin layer which made the outermost surface of a base material contain the photocatalyst at low cost.

Next, examples of the photocatalytic sheet of the present invention will be described.
First, as a base material 2, PTFE is about 0.2 mm as a first fluororesin layer 3 on both sides of glass fiber (FGT600: manufactured by Chuko Kasei Kogyo) having an average thickness of 0.4 mm, a second fluororesin Layer 4 was coated with 10 μm of FEP. Finally, the FEP layer which is the third fluororesin layer 5 containing the photocatalyst was coated with 3 μm.
FIG. 6 is a table showing the composition of the dispersant used in the production of the third fluororesin layer 5 containing the photocatalyst in Example 1. As the dispersant, an aqueous dispersion using an anatase type TiO ₂ having an aqueous dispersion of FEP (solid content of 54% by weight, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and having a particle diameter of 1 nm to 100 nm is used. 62.8 kg of solid content (28% by weight, special order product), 94.4 kg of purified water, 1.8 kg of silicon surfactant (manufactured by Nihon Unicar Co., Ltd., L-77) (1 wt% of the total) are mixed and stirred Prepared. The weight ratio of FEP and titanium oxide powder is 40:60.
The 3rd fluororesin layer 5 containing the photocatalyst was coat | covered with the following manufacturing process.
First, the dispersant for forming the FEP which is the second fluororesin layer 4 coated on the base material 2 is applied to both sides by a dipping coat method, followed by natural drying, and then at 60 ° C. for 5 minutes. Dried. Next, it baked at 325 degreeC for 10 minute (s), it was made to cool naturally, and FEP which is the 2nd fluorine resin layer 4 was formed.
Next, after the film | membrane which apply | coated the said dispersing agent to the 2nd fluororesin layer 4 by the dipping coating method was naturally dried at normal temperature, it was dried at 60 degreeC for 5 minute (s). Furthermore, after heating and baking at 380 ° C. for 10 minutes, the film was naturally cooled, and the FEP layer as the third fluororesin layer 5 containing the photocatalyst was coated on the second fluororesin layer 4 by 3 μm. Photocatalyst sheet 1 was produced.

The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 7 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Example 2. As the dispersant, 42.3 kg of FEP aqueous dispersion (solid content: 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and an aqueous dispersion using anatase TiO ₂ having a particle diameter of 1 nm to 100 nm are used. (Solid content 28% by weight, custom-made product) 54.4 kg, purified water 81.5 kg, silicon surfactant (manufactured by Nihon Unicar Co., Ltd., L-77) 1.8 kg (1% by weight of the total), Stir to prepare. The weight ratio of FEP and titanium oxide powder is 60:40. And the photocatalyst sheet 1 of this invention was manufactured according to the manufacturing process similar to Example 1. FIG.

The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 8 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Example 3. As the dispersant, an aqueous dispersion using 58.9 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and anatase TiO ₂ having a particle diameter of 1 nm to 100 nm. (Solid content 28 wt%, custom-made product) 48.6 kg, purified water 70.7 kg, silicon surfactant (Nihon Unicar Co., Ltd., L-77) 1.8 kg (1 wt% of the total), Prepared by stirring. The weight ratio of FEP and titanium oxide powder is 70:30. And the photocatalyst sheet 1 of this invention was manufactured according to the manufacturing process similar to Example 1. FIG.

The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 9 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Example 4. The dispersant is an aqueous dispersion using 80.9 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and anatase TiO ₂ having a particle diameter of 1 nm to 100 nm. (Solid content 28% by weight, custom-made product) 39 kg, purified water 58.3 kg, silicon surfactant (manufactured by Nippon Unicar Co., Ltd., L-77) 1.8 kg (1% by weight of the total) mixed and stirred And prepared. The weight ratio of FEP and titanium oxide powder is 80:20. And the photocatalyst sheet 1 of this invention was manufactured according to the manufacturing process similar to Example 1. FIG.

The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 10 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Example 5. As the dispersant, an aqueous dispersion using 117.6 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and anatase TiO ₂ having a particle diameter of 1 nm to 100 nm is used. (Solid content 28 wt%, custom-made product) 25.2 kg, purified water 35.4 kg, silicon surfactant (manufactured by Nihon Unicar Co., Ltd., L-77) 1.8 kg (1 wt% of the total), Stir to prepare. The weight ratio of FEP and titanium oxide powder is 90:10. And the photocatalyst sheet 1 was manufactured according to the manufacturing process similar to Example 1. FIG.

Next, Example 6 which manufactured the photocatalyst sheet | seat 20 of this invention is demonstrated.
As the base material 2, glass fiber (FGT600: manufactured by Chuko Kasei Kogyo Co., Ltd.) having an average thickness of 0.4 mm is coated on both surfaces of PTFE as the first fluororesin layer 3, and both surfaces of the PTFE layer are coated. Using the FEP dispersant of Example 1, the FEP layer having a thickness of 10 μm, which is the second fluororesin layer 4 ′ containing the photocatalyst, and the third fluororesin layer 5 containing the photocatalyst A photocatalytic sheet 20 was manufactured by sequentially laminating a FEP layer having a thickness of 3 μm. The dispersant for forming the FEP layer containing the photocatalyst was the same as in Example 2, and the weight ratio of FEP to titanium oxide powder was 60:40.

Next, Comparative Example 1 will be described.
The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 11 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Comparative Example 1. The composition of the dispersant is an aqueous system using 14.6 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and anatase TiO ₂ having a particle size of 1 nm to 100 nm. Dispersion (solid content 28 wt%, custom-made product) 65.7 kg, purified water 97.9 kg, silicon surfactant (Nihon Unicar Co., Ltd., L-77) 1.8 kg (1 wt% of the total) Prepared by mixing and stirring. The weight ratio of FEP and titanium oxide powder is 30:70. And the photocatalyst sheet of the comparative example 1 was manufactured according to the manufacturing process similar to Example 1. FIG.

Next, Comparative Example 2 will be described.
The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 12 is a table showing the composition of the dispersant used for the third fluororesin layer 5 containing a photocatalyst in Comparative Example 2. The composition of the dispersant is 8.8 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J), and an aqueous system using anatase TiO ₂ having a particle diameter of 1 nm to 100 nm. Dispersion (solid content 28% by weight, custom-made product) 67.5 kg, purified water 101.9 kg, silicon surfactant (manufactured by Nippon Unicar Co., Ltd., L-77) 1.8 kg (1% by weight of the total) Prepared by mixing and stirring. The weight ratio of FEP to titanium oxide powder is 20:80. And the photocatalyst sheet of the comparative example 2 was manufactured according to the manufacturing process similar to Example 1. FIG.

Next, Comparative Example 3 will be described.
The FEP was formed as the third fluororesin layer 5 containing the photocatalyst in the uppermost layer of the substrate in the same manner as in Example 1 except that the dispersant composition of the FEP was changed.
FIG. 13 is a table showing the composition of the dispersant used in the third fluororesin layer 5 containing a photocatalyst in Comparative Example 3. The composition of the dispersant is 4.1 kg of FEP aqueous dispersion (solid content 54 wt%, manufactured by Mitsui DuPont Fluorochemical Co., Ltd., 120-J) and an aqueous system using anatase TiO ₂ having a particle diameter of 1 nm to 100 nm. Dispersion (solid content 28% by weight, custom-made product) 70.2 kg, purified water 103.9 kg, silicon surfactant (Nihon Unicar, L-77) 1.8 kg (1% by weight of the total) Prepared by mixing and stirring. The weight ratio of FEP and titanium oxide powder is 10:90. And the photocatalyst sheet of the comparative example 3 was manufactured according to the manufacturing process similar to Example 1. FIG.

Next, Comparative Example 4 will be described.
A sheet having a conventional structure was produced by the same production method as in Example 1 except that the photocatalyst was not added to the third fluororesin layer as the uppermost layer.

The photocatalyst sheet manufactured in Examples 1 to 6 and the sheet manufactured in Comparative Examples 1 to 4 were used for the construction of a membrane structure building, and thermal bonding characteristics and evaluation of dirt exposed to the outdoors were performed.
FIG. 14 is a table showing thermal bonding characteristics of Examples and Comparative Examples and evaluation results of dirt exposed to the outdoors. The table shows the weight% of the photocatalyst in the third fluororesin layer in each example and each comparative example, the thermal bonding characteristics corresponding to the weight%, and the evaluation results of dirt from outdoor exposure. The thermal bonding characteristics were performed by peeling the thermal bonding portion between the photocatalyst sheets at a rate of approximately 20 mm / min with a tester or a tester's hand. The thermal bonding characteristics indicate that the fluororesin layers are completely melted and the entire fluororesin layer is completely peeled off from the glass fiber as the base material as indicated by a circle, and peeling occurs between other fluororesin layers Are indicated by crosses.
As is apparent from the figure, Examples 1 to 6 and the photocatalysts in which the weight% (hereinafter referred to as the weight% of the photocatalyst as appropriate) in the third fluororesin layer containing the photocatalyst is 10% to 60%. The thermal bonding property of Comparative Example 4 not contained is good.

  On the other hand, in Comparative Examples 1 to 3 in which the weight percent of the photocatalyst was 70% to 90%, the thermal bonding characteristics were poor. As described above, the reason why the photocatalyst is less than 70% by weight is that the photocatalyst contained in the third fluororesin layer 5 increases, so that the first fluororesin 5 and the first layer underneath the first fluorocatalyst 5 are increased. This is presumably because the adhesion between the fluororesin layer 3 and the second fluororesins 4 and 4 ′ decreases.

For the evaluation of dirt on outdoor exposure, the sheets of the above-mentioned Examples and Comparative Examples were exposed to the outdoors for 12 months, and then the dirt on the sheet surface was evaluated. A sheet with no dirt attached is indicated by a mark with good, a sheet with little dirt attached is indicated with a mark with Δ, and a sheet with dirt attached is indicated with a mark with a defect. Outdoor exposure was performed on the rooftop of the applicant's Spatial Technology Research Institute (Hirakata City, Osaka Prefecture).
As is apparent from the figure, Examples 1-4 and Example 6 in which the weight percent of the photocatalyst contained in the uppermost fluororesin layer 5 is 20% to 60% are excellent in antifouling property. Further, it can be seen that in Example 5 in which the weight% of the photocatalyst is 10% and Comparative Examples 1 to 3 in which the photocatalyst is 70% or more, dirt hardly adheres. On the other hand, it turns out that the conventional sheet | seat which does not contain a photocatalyst in the uppermost layer of the comparative example 4 does not have antifouling property.

In Example 5, the antifouling property is slightly deteriorated because the photocatalyst in the fluororesin layer is small (10% by weight), but the antifouling property of Comparative Example 4 containing no photocatalyst is The antifouling property is much higher than that without, and the effect of adding a photocatalyst is remarkable.
On the other hand, when the photocatalyst is contained in a large amount as in Comparative Examples 1 to 3, the antifouling property is reduced because the fluororesin layer 3 containing the uppermost photocatalyst and the fluororesin layer below the fluororesin layer 3 are contained. Due to poor thermal bonding properties with 3 and 4, the fluororesin layer 3 containing the photocatalyst is lost over time, and the lower fluororesin layers 4 and 5 not containing the photocatalyst are in direct contact with the outside air. Presumed to be.
At this time, it was found that the photocatalyst sheet 20 of Example 6 was least contaminated with respect to the antifouling properties of the heat-bonded portions of Examples 1 to 6 having good antifouling properties. This is because, since the photocatalyst is contained in both the third fluororesin layer 5 and the second fluororesin layer 4 ′ as the uppermost layer, the fluororesin layer containing the photocatalyst is thick. Even if it passes, it is estimated that the defect by the damage | wound etc. of the fluororesin layer 5 containing the photocatalyst hardly arises.
Thus, it can be seen that high antifouling properties and good thermal bonding characteristics can be obtained when the weight percent of titanium oxide with respect to the fluororesin of the third fluororesin layer containing the photocatalyst is in the range of 10 to 60%.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. . For example, the substrate and the fluororesin described in the above embodiment can be appropriately selected according to the purpose, and the composition of the fluororesin dispersant containing the photocatalyst can be appropriately selected. .

It is sectional drawing which shows typically an example of the photocatalyst sheet structure by this invention. It is sectional drawing which shows typically the other example of the photocatalyst sheet structure by this invention. It is a cross section which shows typically another structure of the photocatalyst sheet of this invention. It is an expanded sectional view which shows the structure of the surface side of the base material which coat | covered the 3rd fluororesin layer containing the photocatalyst of this invention. It is a flowchart which shows the manufacturing process of the photocatalyst sheet of this invention sequentially. In Example 1, it is a table | surface which shows the composition of the dispersing agent used for manufacture of the 3rd fluororesin layer containing the photocatalyst. In Example 2, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Example 3, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Example 4, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Example 5, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Comparative Example 1, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Comparative Example 2, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. In Comparative example 3, it is a table | surface which shows the composition of the dispersing agent used for the 3rd fluororesin layer containing the photocatalyst. It is a table | surface which shows the thermal-joining characteristic of an Example and a comparative example, and the evaluation result of the stain | pollution | contamination of outdoor exposure.

Explanation of symbols

1, 10, 20: Photocatalyst sheet 2: Base material 3: First fluororesin layer 4: Second fluororesin layer 4 ′: Second fluororesin layer containing photocatalyst 5: Photocatalyst containing second 3 fluororesin layer 5a: surface of third fluororesin layer containing photocatalyst 7: photocatalyst in third fluororesin layer 8: photocatalyst exposed on surface of third fluororesin layer

Claims (22)

A substrate;
A first fluororesin layer coated on the substrate;
A second fluororesin layer coated on the first fluororesin layer;
A photocatalyst sheet comprising: a third fluororesin layer containing a photocatalyst coated on the second fluororesin layer. A substrate;
A first fluororesin layer coated on the substrate;
A second fluororesin layer containing a photocatalyst coated on the first fluororesin layer;
A photocatalyst sheet comprising: a third fluororesin layer containing a photocatalyst coated on the second fluororesin layer.   3. The photocatalytic sheet according to claim 1, wherein the base material is made of a fiber, and the surface shape thereof is any one of a flat surface, a rough uneven surface, and a mesh shape.   The base material is glass fiber, the first fluororesin layer is PTFE, the second fluororesin layer is FEP or PFA, and the third fluororesin layer is FEP. The photocatalyst sheet according to any one of claims 1 to 3.   The substrate is glass fiber, the first fluororesin layer is PTFE, the second fluororesin layer is any one of PTFE, FEP, and PFA, and the third fluororesin The photocatalyst sheet according to any one of claims 1 to 3, wherein the layer is made of FEP.   The melting point of the first fluororesin layer is higher than the melting points of the second fluororesin layer and the third fluororesin layer, and the melting point of the second fluororesin layer is the melting point of the third fluororesin layer. The photocatalyst sheet according to claim 1, wherein the photocatalyst sheet is the same as or higher than the photocatalyst sheet.   The photocatalytic sheet according to claim 6, wherein the second fluororesin layer and the third fluororesin layer are made of the same fluororesin.   The melting point of the first fluororesin layer is higher than the melting points of the second fluororesin layer and the third fluororesin layer, and the melting point of the first fluororesin layer is the melting point of the second fluororesin layer. The photocatalyst sheet according to claim 1, wherein the photocatalyst sheet is the same as or higher than the photocatalyst sheet.   The photocatalytic sheet according to claim 8, wherein the first fluororesin layer and the second fluororesin layer are made of the same fluororesin.   The photocatalytic sheet according to claim 1 or 2, wherein the first fluororesin layer and the third fluororesin layer are made of the same fluororesin.   The melting point of the third fluororesin layer is higher than the melting points of the first fluororesin layer and the second fluororesin layer, and the melting point of the second fluororesin layer is the melting point of the first fluororesin layer. The photocatalytic sheet according to claim 1, wherein the photocatalytic sheet is the same as or higher than the photocatalytic sheet.   The photocatalytic sheet according to claim 11, wherein the first fluororesin layer and the second fluororesin layer are made of the same fluororesin.   The melting point of the third fluororesin layer is higher than the melting points of the first fluororesin layer and the second fluororesin layer, and the melting point of the third fluororesin layer is the melting point of the second fluororesin layer. The photocatalyst sheet according to claim 1, wherein the photocatalyst sheet is the same as or higher than the photocatalyst sheet.   The photocatalyst sheet according to claim 11, wherein the third fluororesin layer and the second fluororesin layer are made of the same fluororesin. The photocatalyst sheet according to claim 1 or 2, wherein the photocatalyst is made of at least titanium oxide (TiO ₂ , TiO ₃ ).   The photocatalyst sheet according to any one of claims 1, 2, and 15, wherein the photocatalyst has a portion exposed on the third fluororesin layer.   17. The photocatalyst sheet according to claim 1, wherein the photocatalyst in the third fluororesin layer is 10% to 60% by weight. Coating the first fluororesin layer on the substrate;
Coating the second fluororesin layer on the first fluororesin layer;
And a step of coating a third fluororesin layer containing a photocatalyst on the second fluororesin layer. Coating the first fluororesin layer on the substrate;
Coating a second fluororesin layer containing a photocatalyst on the first fluororesin layer; and coating a third fluororesin layer containing a photocatalyst on the second fluororesin layer. A method for producing a photocatalyst sheet, comprising:   A covering step for forming the first fluororesin layer, the second fluororesin layer or the second fluororesin layer containing the photocatalyst, and the third fluororesin layer containing the photocatalyst. Is performed continuously, The manufacturing method of the photocatalyst sheet of Claim 18 or 19 characterized by the above-mentioned.   19. The step of coating a third fluororesin layer containing a photocatalyst on the base material previously coated with the first fluororesin layer and the second fluororesin layer is performed. Or the manufacturing method of the photocatalyst sheet of 19. A third fluororesin layer containing the photocatalyst,
More than the melting | fusing point of the fluororesin used for the process of apply | coating the dispersing agent for fluororesins containing the titanium oxide microparticles | fine-particles used as a photocatalyst on the said 2nd fluororesin layer, a drying process, and a said 3rd fluororesin layer The photocatalyst according to any one of claims 18 to 21, wherein the photocatalyst is coated by a step including a step of sintering at a high temperature and exposing the photocatalyst to a surface of the third fluororesin layer. Sheet manufacturing method.