JP2000070709A - Material with titanium dioxide crystal oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material exhibiting superior photocatalytic activity, having superior characteristics such as antibacterial action, antifouling action, ultra- hydrophilic action, deodorizing action and oil decomposition action and usable in various uses. SOLUTION: A titanium dioxide crystal oriented film is formed by atmospheric pressure opening type CVD on the surface of a substrate having many minute open holes and on the entire insides of the open holes. The substrate is preferably a reticular body having 0.01-3.0 mm opening at 3-50% opening rate or a plate-shaped body having through holes of 0.01-3.0 mm diameter 3-50% opening rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal orientation film made of titanium dioxide formed on a surface of a base material made of various materials such as metal, glass, porcelain, ceramics, carbon and plastic and having many fine holes. Related to the formed material.
The material having a titanium dioxide crystal orientation film of the present invention exhibits photocatalytic activity, has excellent properties such as antibacterial action, antifouling action, superhydrophilic action, deodorant action, oil decomposition action, and cooking utensils.
It is widely used for kitchen utensils such as tableware and refrigerators, medical equipment, toilet and toilet materials, various filters, air conditioners, electronic components, building materials, road-related materials, and the like.

[0002]

2. Description of the Related Art It has been known that a titanium dioxide thin film has various functions by a photocatalytic reaction, and a titanium dioxide thin film is formed on a surface of various base materials such as a metal material, a semiconductor element and a plastic material to prevent reflection. It is also known to use as a material, a sensor material, an insulating material, and the like. The present inventors previously sprayed a titanium alkoxide vaporized under atmospheric pressure release together with an inert gas serving as a carrier onto various heated substrate surfaces, thereby forming a titanium dioxide crystal orientation film having excellent photocatalytic activity. It has been found that a material having the same can be obtained efficiently and proposed. (JP-A-10-15239)
No. 6)

[0003]

The inventors of the present invention have conducted intensive studies to obtain a material having a further excellent photocatalytic activity. The inventors have found that the material on which the film is formed exhibits extremely excellent photocatalytic activity, and have completed the present invention. That is, the present invention provides a material that exhibits extremely excellent photocatalytic activity, has excellent properties such as antibacterial action, antifouling action, superhydrophilic action, deodorant action, and oil decomposition action, and is used for a wide range of applications. It is intended to provide.

[0004]

According to the present invention, the following structure is adopted to solve the above-mentioned problems. 1. A material in which a titanium dioxide crystal orientation film is formed on the surface of a substrate having many fine holes. 2. The opening is 0.01 to 3.0 mm, and the opening ratio is 3 to 50.
The material according to 1, wherein the material is a base material having a mesh percentage of 0.1%. 3. The hole diameter is 0.01 to 3.0 mm, and the opening ratio is 3 to 50%.
2. The material according to 1, wherein the base material is a plate-like body having through holes. 4. The material according to any one of claims 1 to 3, wherein a titanium dioxide crystal orientation film is formed on the entire inner surface of the opening. 5. The titanium dioxide crystal oriented film is characterized in that it is oriented in a direction perpendicular to the crystal surface in a direction selected from crystal planes consisting of (001), (100), (211), (101) and (110). 5. The material according to any one of 1 to 4, wherein 6. 6. The material according to any one of items 1 to 5, wherein the thickness of the titanium dioxide crystal orientation film is 0.1 μm or more. 7. The grain size of the crystal forming the titanium dioxide crystal orientation film is 0.01 to 1 μm, and the grain size distribution is substantially an average ±
The material according to any one of claims 1 to 6, which is 100%. 8. 8. The material according to any one of 1 to 7, wherein the titanium dioxide crystal orientation film has photocatalytic activity. 9. 9. The material according to any one of 1 to 8, wherein the titanium dioxide crystal orientation film is formed by an atmospheric pressure open type CVD method. 10. The material according to any one of claims 1 to 9, wherein the substrate is selected from metal, glass, ceramics, ceramics, carbon and plastic. 11. A multilayer structure made of the material described in any one of the above items 11 to 10. 12. A filter comprising the multilayer structure described in 12.11.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a substrate having a large number of fine openings is used as a substrate on which a titanium dioxide crystal orientation film is formed. In the present invention, the fine opening means that the opening (distance between adjacent wires constituting the mesh) is 0.01.
Mesh having a diameter of ~ 3.0 mm or a pore size of 0.01 to 3.0 mm;
mm means a through hole. Examples of such a base material include (1) a reticulated body made of various materials, (2) a plate-shaped body made of various materials provided with through holes by machining, electron beam or the like, and (3) steel wool. And a multilayer structure in which fibers having a small diameter are overlapped and joined without knitting. Examples of the reticulated body serving as a base include reticulated bodies made of inorganic fibers such as metal fibers, glass fibers, and carbon fibers, and heat-resistant plastic fibers. The reticulated body can be constructed by weaving these fibers by plain weaving, twill weaving, or the like, or by laminating these fibers without weaving and fixing them if necessary. Preferred meshes include a wire mesh obtained by weaving a metal wire such as a stainless wire or a steel wire. The wire diameter of the metal constituting the wire mesh is about 0.01 to 3.0 mm, preferably about 0.02 to 1.0 mm. The mesh size of the wire mesh is about 0.01 to 3.0 mm, preferably about 0.02 to 1.5 mm, and the porosity is 3 to 50%, preferably 10 to 40%.

There is no particular limitation on the material constituting the plate-like body having a through-hole serving as a base material.
Any material capable of forming fine through-holes, such as ceramics and plastics, can be used, but metals such as steel, stainless steel, aluminum, and various alloys in terms of drilling workability and formability. It is preferred to use The shape of the through-hole formed in the plate-like body is not limited, and may be any shape such as a perfect circle, an ellipse, a long hole, and a square hole. The hole diameter in the present invention means the diameter in the minor axis direction in other than a perfect circle such as an ellipse, a long hole, and a square hole. The arrangement state of the holes is arbitrary, such as side-by-side or zigzag. The holes may be formed diagonally to the surface of the base material in addition to the holes formed perpendicular to the surface of the base material. The preferred hole diameter of the through hole is 0.05 to 1.5 mm, particularly preferably 0.1 to 1.0 mm. If the pore size is too small, the pores may be blocked by titanium dioxide when forming a titanium dioxide crystal orientation film on the substrate surface, while if the pore size is too large, Since the entire surface including the portion is relatively small, it is difficult to impart sufficient photocatalytic activity to the material. There is no limitation on the method of forming the through-holes in the plate-shaped base material, and a known method such as machining such as punching or punching with an electron beam can be used.

[0007] The shape of the substrate constituting the material of the present invention is not particularly limited, and may be any shape such as a flat plate, a cylinder, a hemisphere, a truncated cone, and a tray. The material of the present invention can be produced by forming a titanium dioxide crystal orientation film on the surface of a substrate previously formed into a desired shape, and also forming a titanium dioxide crystal orientation film on a flat substrate surface. It can also be manufactured later by shaping the base material into a desired shape. Further, after forming the titanium dioxide crystal orientation film on the fibrous base material, the fibers may be formed into a desired shape such as a network. Further, the material of the present invention may be a multilayer structure using a plurality of substrates having titanium dioxide crystal orientation films of various shapes. In such a multilayer structure, since the surface area of the titanium dioxide crystal orientation film having photocatalytic activity increases, for example, air,
The purifying ability when used for applications such as filters for water and food and drink is remarkably increased.

The type, size, shape, etc. of the substrate of the material of the present invention can be appropriately selected according to the technical field, purpose, application, etc., in which the material is used. For example, if the material is flexible and requires moldability, a material having a net as a base material can be used. When strength or rigidity is required, a material obtained from a base material having a through-hole formed in a plate having an appropriate thickness can be used. Furthermore, you may use combining the material which has the flexibility which uses a net-like body as a base material, and the base material which has a rigid plate-like body which has a through-hole.

The titanium dioxide crystal oriented film of the present invention means an oriented film made of a single crystal of titanium dioxide and an oriented film made of a polycrystal. Here, the single-crystal alignment film is not limited to a single-crystal alignment film, which is generally used in the field of materials science, and the alignment film has the same three-dimensional crystal orientation as the alignment film. It also includes those composed of a large number of crystals. The material having a titanium dioxide crystal oriented film oriented in a specific direction according to the present invention is obtained by coating a vaporized titanium alkoxide (raw material complex) together with an inert gas serving as a carrier on the surface of a substrate heated under atmospheric pressure. By spraying, it can be manufactured efficiently.

As a raw material for forming the titanium dioxide crystal orientation film, a titanium alkoxide represented by the general formula Ti (OR) ₄ is used. (In the formula, R represents an alkyl group having 2 to 10 carbon atoms.) Among these titanium alkoxides, Ti (OC ₂ H
₅ ) ₄ (hereinafter abbreviated as “TTE”), Ti (O-i
-C ₃ H _{7) 4} (hereinafter, abbreviated as "TTIP"), T
_{i (O-n-C 4} H 9) 4 ( hereinafter, abbreviated as "TTNB") be preferred, TTIP is fast deposition rate of titanium dioxide, it is easy to control the crystal structure of the alignment film obtained Therefore, it is a particularly preferable raw material.

In the present invention, the raw material complex is vaporized in a vaporizer and sprayed together with an inert gas serving as a carrier onto the surface of a heated substrate under atmospheric pressure, thereby forming a crystal orientation film of titanium dioxide on the surface of the substrate. Form. The inert gas serving as a carrier is not particularly limited, and any commonly used inert gas such as nitrogen, helium, and argon can be used.However, it is preferable to use nitrogen gas from the viewpoint of economy and the like. Among them, it is particularly preferable to use nitrogen gas from which water has been removed through liquid nitrogen. The vaporization temperature of the raw material complex is adjusted according to the type of the raw material, for example, TTE, TTIP, TT
In the case of NB, the temperature is preferably set to 70 to 150 ° C.

When the raw material complex carried by the inert gas carrier is sprayed on the surface of the substrate heated under atmospheric pressure, the material complex is sprayed onto the surface of the substrate moving from a slit type nozzle, thereby forming a net-like, plate-like, It is possible to continuously form a crystal orientation film of titanium dioxide on the surface of a base material preformed in various shapes such as a cylinder, a hemisphere, a truncated cone, or a dish or tray. In the conventional technique of using a paint containing titanium dioxide and forming a titanium dioxide coating on the surface of the substrate by coating or dipping, when a substrate having a large number of fine holes is used as the substrate, the coating is At the time of formation, the inside of the opening was closed by titanium dioxide particles, and it was difficult to obtain a material having a through hole. In addition, even when a through hole is obtained, a titanium dioxide film cannot be formed on the entire inner surface of the hole, and only a film in which the inner portion of the hole is partially covered with the titanium dioxide film is obtained. there were. In the present invention, a material having a titanium dioxide crystal orientation film formed on the entire inner surface of the fine opening of the base material by employing an atmospheric pressure open type CVD method without using a solvent or the like, and having a through hole For the first time. Further, by adjusting the vaporization temperature and supply amount of the raw material, the flow rate of the carrier gas, the substrate temperature, and the like, the crystal structure of the obtained crystal orientation film is controlled, the orientation direction of the crystal orientation film, the thickness of the film, It is possible to adjust the crystal grain size and grain size distribution to desired ones.

In the present invention, the titanium dioxide crystal orientation film formed on the base material surface is (001) perpendicular to the crystal surface.
It is preferable that the crystal is oriented in a direction selected from the crystal plane composed of (100), (211), (101), and (110). The titanium dioxide crystal oriented film oriented in these specific directions exhibits the following various photocatalytic actions when irradiated with light, particularly ultraviolet rays. (1) It has a remarkable antibacterial action (bacteriostatic action and sterilization action) and can decompose dead bacteria and toxins and other bacterial products, thereby preventing dirt and exhibiting a persistent antibacterial action. I do. (2) Prevents the adhesion of dirt, decomposes the dirt, and easily removes it by naturally falling rain or water washing to maintain the surface gloss. (3) It decomposes substances that cause odor, and has a deodorizing and deodorizing action. (4) The contact angle with water decreases due to the irradiation of ultraviolet rays, becomes close to 0 degrees, and water does not repel. Therefore, no water droplets are formed on the surface and a uniform water film is formed, so that fogging can be prevented. (5) Nitrogen oxides (NOx) and sulfur oxides (S
0x) to purify the air. (6) Decompose water and food and drink by decomposing contaminants in water and food and drink such as organic halogen compounds and oils. (7) Convert solar energy into electricity by combining it with an appropriate dye. Therefore, the material having a titanium dioxide crystal oriented film oriented in a specific direction on the surface thereof is a medical device, tableware, cooking utensil, refrigerator, refrigerated vehicle, washroom or kitchenware, interior material, exterior material, taking advantage of the above characteristics. Can be widely used as materials for building materials, lighting equipment, road-related materials, air conditioner filters, filters for water and food processing, electronic components such as capacitors and IC chips, and solar power generation equipment. You can do it.

In the material of the present invention, a substrate having a large number of fine holes is used, and a titanium dioxide crystal orientation film is formed on the entire inner surface of the holes, and the holes penetrate. As a result, the total surface area of the titanium dioxide crystal orientation film having photocatalytic activity is greatly increased, and thus the obtained photocatalytic activity is also significantly increased, as compared to a material in which a titanium dioxide crystal orientation film is simply formed on the substrate surface. . In particular, when a plurality of the materials of the present invention are used and a multilayer structure is formed with spacers or the like interposed therebetween as necessary, the total surface area of the titanium dioxide crystal orientation film having photocatalytic activity is dramatically increased. The obtained photocatalytic action is further improved. Above all, a multilayer structure composed of a material having a net-like body as a base material also has flexibility, moldability, etc., so that, for example, various filters can be used for purifying air and exhaust gas, purifying water, beer, and juice. It is particularly useful for applications such as filtration of food and drink.

In the present invention, even if the crystal orientation film oriented in a specific direction is composed of a titanium dioxide crystal oriented in only one direction, the titanium dioxide film oriented in two or more directions is used. The same effect can be obtained even if the device is made of a crystal. According to the present invention, the thickness of the crystal orientation film formed on the surface of the substrate can be any desired value. Since various characteristics can be imparted, the thickness is usually 0.1 to 10 μm, preferably 0.2 to 2.0 μm. In addition, when the particle size of the crystal forming the alignment film is substantially the same as the wavelength of visible light and ultraviolet light, remarkable anticatalytic and other photocatalytic activities are obtained. If you do, the effect is remarkable. Therefore, the crystal grain size is 0.01 to 1 μm.
m, it is preferable that the crystal orientation film has a particle size distribution substantially having an average value of ± 100%, and the particle size distribution has an average value of ± 50%.
It is particularly preferable that the crystal orientation film is as follows. The particle size distribution of the crystals in the present invention is calculated as follows according to a conventional method in the field of materials science. That is, as shown in FIG. 8, in the histogram drawn with the particle diameter (maximum diameter) of each crystal constituting the alignment film on the horizontal axis and the number of crystals on the vertical axis, the maximum value Y ₁ of the vertical axis is obtained. The average value of the crystal grain size and the grain size distribution are calculated for those having 50% or more (shaded portions in FIG. 8).

Another preferred material is one in which the crystal orientation film of titanium dioxide has a network structure. As these materials, if necessary, after forming a crystal orientation film of titanium dioxide on the surface of the base material, those subjected to an annealing treatment in an oxygen atmosphere can be used. In the present invention, that the crystal orientation film has a network structure means a state in which needle-like crystals intersect or a state in which the crystals are arranged in a honeycomb shape. Then, the annealing treatment in an oxygen atmosphere means that the crystal orientation film made of titanium dioxide is heated at 300 ° C. to 60 ° C. in an oxygen stream using an electric furnace at atmospheric pressure.
This means heating at an arbitrary temperature of 0 ° C. for several hours.

According to the present invention, a film of silver, copper or their oxides can be further formed on the surface of the crystal orientation film composed of titanium dioxide. In this case, a material having further improved antibacterial properties is used. Obtainable. To form a film of silver, copper or their oxides on the surface of the titanium dioxide crystal orientation film, after forming the titanium dioxide crystal orientation film by the above method, cut or mold into a desired shape if necessary, and coat. A silver, copper or oxide film of silver or copper may be formed by an ordinary method such as a method, an immersion method, a sputtering method, and a thermal CVD method. It is preferable to use a sputtering method to form a silver or copper film and a method similar to the present invention to form a film of these oxides. These coatings do not necessarily need to be formed up to the inside of the opening, and may be provided only on the front surface and / or the back surface of the base material.

[0018]

Next, the present invention will be described with reference to examples.
It goes without saying that the present invention is not limited by these examples. In the following examples, a titanium dioxide crystal orientation film was formed on the surface of a base material using an apparatus similar to the apparatus described in JP-A-10-152396.

(Example 1) TTIP was used as a raw material complex, a raw material vaporization temperature was 120 ° C, and a nitrogen gas flow rate was 1.5 dm ^3.
/ Min. Vaporized the TTIP. As a base material, a 100-mesh wire mesh (aperture 0.154 mm, aperture ratio 35%) made of a stainless wire having a wire diameter of 0.1 mm was used.
In a heating furnace installed at a temperature of 400 ° C. in a high-temperature zone, 11
1.75 m / min. The above-mentioned raw material gas mixture was sprayed from a slit type nozzle having a slit having a width of 1.0 mm to form a 1.0 μm-thick titanium dioxide polycrystalline alignment film on the surface of the substrate. The state of the obtained titanium dioxide polycrystalline alignment film was measured by a scanning electron microscope (hereinafter referred to as “S
Observed by EM ") and X-ray diffraction, the polycrystalline alignment film had an anatase structure and was oriented in the (001) plane perpendicular to the crystal surface forming the film. Also, the grain size of the crystal is 0.01 to 0.5 μm
The particle size distribution was 0.25 ± 0.25 μm. An SEM photograph of the surface of this polycrystalline alignment film is shown in FIG.
2) and FIG. 2 (35,000 times magnification). As shown in FIG. 1, this polycrystalline alignment film is formed uniformly over the entire periphery of the stainless wire constituting the wire netting. FIG. 2 shows that this polycrystalline alignment film has a network structure.

Example 2 As a substrate, a wire diameter of 0.025 was used.
A titanium dioxide polycrystal having a film thickness of 1.0 μm was formed on the surface of the substrate in the same manner as in Example 1 except that a 500-mesh wire mesh (aperture 0.026 mm, opening ratio: 26%) made of a stainless steel wire having a thickness of 2.5 mm was used. An alignment film was formed. The obtained polycrystalline alignment film had an anatase structure and was oriented in the (001) plane perpendicular to the crystal surface forming the film. The particle size distribution of the crystals was 0.25 ± 0.25 μm. FIG. 3 shows an SEM photograph of the surface of the polycrystalline alignment film.
(Magnification 150 times) and FIG. 4 (magnification 5000 times).
As shown in FIG. 3, the polycrystalline alignment film is formed uniformly over the entire circumference of the stainless wire forming the wire net.

(Example 3) As a substrate, a stainless steel plate having a thickness of 1 mm and a through hole formed by an electron beam (hole diameter: 0.1 mm, opening ratio: 38%) was used.
In the same manner as in Example 1, a polycrystalline oriented titanium dioxide film having a thickness of 1.0 μm was formed on the substrate surface. The obtained polycrystalline alignment film had an anatase structure and was oriented in the (001) plane perpendicular to the crystal surface forming the film. The particle size distribution of the crystals was 0.25 ± 0.25 μm. SEM photographs of the surface of the polycrystalline alignment film are shown in FIGS. 5 (50 ×), 6 (500 ×), and 7 (500 ×).
0 times). This polycrystalline alignment film is formed on the entire inner surface of the through hole as shown in FIG. FIG. 7 shows that the polycrystalline alignment film has a network structure.

(Photocatalytic activity test) The photocatalytic activity of the material having a titanium dioxide crystal orientation film obtained in each of the above examples was tested by the following method. The oil-deposited finger was pressed against the surface of the titanium dioxide crystal orientation film to cause the oil to adhere to the surface of the film, and the film was irradiated with a UV lamp at a distance of 100 mm, and the oil decomposition process was visually observed. For comparison, a 1 mm thick stainless steel plate having no through hole as a substrate
A similar test was performed using a material on which a titanium dioxide polycrystalline alignment film was formed under the same conditions as described above (hereinafter, referred to as “Comparative Example”). In each of the Examples and Comparative Examples of the present invention, a stripe pattern of a fingerprint is clearly observed immediately after the oil is deposited, but the decomposition of the oil starts due to the photocatalytic activity of the titanium dioxide crystal orientation film immediately after irradiation with a UV lamp, In a few seconds, the fingerprint trace disappeared, and the lipophilicity slightly increased the surface area of the oil.
When the irradiation with the UV lamp was continued, the decomposition of the oil progressed, and the surface area of the oil was reduced and disappeared. In the comparative example, the oil disappeared after 7 days. However, in the material having a large number of fine holes obtained in each of the above examples, the oil disappeared after 4 to 5 days. From this,
The material of the present invention in which a titanium dioxide crystal orientation film is formed on the surface of a substrate having a large number of fine holes is more excellent than a material in which a titanium dioxide crystal orientation film is formed on a mere plate-like substrate. It was found to have photocatalytic activity.

[0023]

According to the material of the present invention, a titanium dioxide crystal orientation film is formed on the entire inner surface of a hole by using a substrate having a large number of fine holes. As a result, the total surface area of the titanium dioxide crystal orientation film having photocatalytic activity is greatly increased as compared to a material in which a titanium dioxide crystal orientation film is simply formed on the substrate surface, and thus the obtained photocatalytic activity is also remarkable. Increase. In particular, when a plurality of the materials of the present invention are used and a multilayer structure is formed with spacers or the like interposed therebetween as necessary, the total surface area of the titanium dioxide crystal orientation film having photocatalytic activity is dramatically increased. The obtained photocatalytic action is further improved. For applications that require flexibility and moldability, a net-like base material is used, and for applications that require strength and rigidity, a plate-like body with through holes is used as the substrate. The material can be selected according to the purpose, and can be applied to a very wide range of applications.

[Brief description of the drawings]

FIG. 1 is an SEM photograph of an example of a titanium dioxide crystal orientation film formed on the surface of a network according to the present invention.

FIG. 2 is a high magnification SE of the titanium dioxide crystal orientation film of FIG.
It is an M photograph.

FIG. 3 is a SEM photograph of another example of a titanium dioxide crystal alignment film formed on the surface of a network according to the present invention.

FIG. 4 shows a high magnification SE of the titanium dioxide crystal orientation film of FIG.
It is an M photograph.

FIG. 5 is an SEM photograph of one example of a titanium dioxide crystal orientation film formed on the surface of a plate having a through hole according to the present invention.

6 is an SEM photograph in which the magnification of the titanium dioxide crystal orientation film of FIG. 5 is increased.

FIG. 7 is a SEM photograph of the titanium dioxide crystal orientation film of FIG. 5 at a further increased magnification.

FIG. 8 is a diagram for explaining a method of calculating a crystal particle size distribution.

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Claims (12)

[Claims] 1. A material in which a titanium dioxide crystal orientation film is formed on the surface of a substrate having a large number of fine holes. 2. The material according to claim 1, wherein the base material is a net having an opening of 0.01 to 3.0 mm and a porosity of 3 to 50%. 3. The material according to claim 1, wherein the base material is a plate having a through-hole having a pore diameter of 0.01 to 3.0 mm and a porosity of 3 to 50%. 4. The material according to claim 1, wherein a titanium dioxide crystal orientation film is formed on the entire inner surface of the opening. 5. A titanium dioxide crystal orientation film having (001), (100), (211), (10) in the direction perpendicular to the crystal surface.
5. A crystal oriented in a direction selected from a crystal plane composed of (1) and (110).
A material according to any one of the preceding claims. 6. A titanium dioxide crystal orientation film having a thickness of 0.1
The material according to any one of claims 1 to 5, wherein the thickness is not less than μm. 7. The crystal forming the titanium dioxide crystal oriented film has a particle size of 0.01 to 1 μm, and the particle size distribution is substantially an average value ± 100%.
A material according to any one of the preceding claims. 8. The material according to claim 1, wherein the titanium dioxide crystal orientation film has a photocatalytic activity. 9. The material according to claim 1, wherein the titanium dioxide crystal orientation film is formed by an atmospheric pressure open CVD method. 10. The material according to claim 1, wherein the substrate is selected from the group consisting of metal, glass, ceramics, ceramics, carbon and plastic. 11. A multilayer structure comprising the material according to any one of claims 1 to 10. 12. A filter comprising the multilayer structure according to claim 11.