WO2015098386A1

WO2015098386A1 - Inorganic filter

Info

Publication number: WO2015098386A1
Application number: PCT/JP2014/080909
Authority: WO
Inventors: 優介畠中; 順二川口
Original assignee: 富士フイルム株式会社
Priority date: 2013-12-27
Filing date: 2014-11-21
Publication date: 2015-07-02
Also published as: TW201532662A

Abstract

Provided is an inorganic filter which has resistance to bending and impact, does not undergo clogging, and has excellent flexibility and filtration capacity. The inorganic filter has an inorganic particle layer comprising inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder, wherein the inorganic binder comprises at least one compound selected from the group consisting of aluminum phosphate, sodium silicate and aluminum chloride and the porosity of the inorganic particle layer is 10 to 70%.

Description

Inorganic filter

The present invention relates to an inorganic filter.

In recent years, the application fields of microfiltration and ultrafiltration technology are expanding, such as protein adsorbents, water purification, air purification, deodorization / denitration / exhaust gas exhaust structures, ozone removal, various virus removal, clean room materials, Gas separation, alkali elution, asbestos monitoring, parasite detection, IR analysis of atmospheric particles, algae analysis in rivers and seawater, red blood cell deformation test, chemotaxis / culture chamber, scanning electron microscope, radiometric analysis, exfoliated cytology In various applications such as fluorescent X-rays, a filter with a precision structure is applied to separation, purification, recovery, concentration, and the like.

Filter materials vary depending on the application, but filters made of inorganic materials are attracting attention due to their high heat resistance and corrosion resistance.
For example, Patent Document 1 describes a ceramic filter made of a ceramic porous body.
Patent Document 2 describes an alumina membrane filter made of an anodized aluminum film.

JP 2010-228949 A JP 2009-50773 A

The manufacturing method of a ceramic filter as described in Patent Document 1 is a method in which a raw material mixture including particles of inorganic material is sintered at high temperature. Therefore, the handling is the same as that of pottery, and there has been a problem that it cannot be processed such as being bent into a desired shape, and is susceptible to impact such as being broken by dropping.
Moreover, since the alumina membrane filter as described in Patent Document 2 basically uses a straight tubular micropore (through hole) as a filtration flow path, fine particles in the object to be processed are clogged in the micropore. There is a problem that the filtration flow rate is reduced.

Therefore, an object of the present invention is to provide an inorganic filter that is resistant to bending and impact and that can suppress the occurrence of clogging and that is excellent in flexibility and filtration amount.

As a result of earnest research to achieve the above-mentioned problems, the present inventor has an inorganic particle layer containing an inorganic particle having an average particle diameter of 0.01 μm or more and an inorganic binder, and the inorganic binder is By using an inorganic filter that is at least one selected from the group consisting of aluminum phosphate, sodium silicate, and aluminum chloride, and the porosity of the inorganic particle layer is 10 to 70%, flexibility and filtration rate Was found to be satisfactory, and the present invention was completed.
That is, this invention provides the inorganic filter of the following structures.

(1) It has an inorganic particle layer containing inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder, and the inorganic binder is made of aluminum phosphate, sodium silicate and aluminum chloride. An inorganic filter that is at least one selected from the group, and the porosity of the inorganic particle layer is 10 to 70%.
(2) The inorganic filter according to (1), which includes a support including a plurality of through holes penetrating in a thickness direction, and the inorganic particle layer is formed in the through holes of the support.
(3) The inorganic filter according to (1), which includes a support including a plurality of passages penetrating in the thickness direction, and the inorganic particle layer is laminated on the support.
(4) The inorganic filter according to (3), wherein inorganic particle layers are laminated on both sides of the support.
(5) The inorganic filter according to any one of (2) to (4), wherein the support is made of aluminum.
(6) The inorganic filter according to any one of (1) to (5), wherein the inorganic particles are composed of at least one selected from the group consisting of oxides, nitrides, hydroxides, inorganic salts, and carbides. .
(7) The inorganic filter according to any one of (1) to (6), wherein the inorganic particle layer has a thickness of 10 μm to 5000 μm.

According to the present invention, it is possible to provide an inorganic filter that is excellent in flexibility and filtration amount.

It is typical sectional drawing which shows an example of suitable embodiment of the inorganic filter of this invention. It is a partial expanded sectional view which expands and shows a part of inorganic filter shown in FIG. It is typical sectional drawing which shows another example of the inorganic filter of this invention. It is typical sectional drawing which shows another example of the inorganic filter of this invention. It is typical sectional drawing which shows another example of the inorganic filter of this invention. It is typical sectional drawing which shows an example of the filter structure containing the inorganic filter of this invention.

Hereinafter, the inorganic filter of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Inorganic filter]
The inorganic filter of the present invention has an inorganic particle layer containing an inorganic particle having an average particle diameter of 0.01 μm or more and an inorganic binder, and the inorganic binder includes aluminum phosphate, sodium silicate, and The inorganic filter is at least one selected from the group consisting of aluminum chloride and has a porosity of the inorganic particle layer of 10 to 70%.
Next, the structure of the inorganic filter of this invention is demonstrated using FIG. 1 and FIG.

FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the inorganic filter of the present invention, and FIG. 2 is a partially enlarged cross-sectional view showing a part of FIG.
As shown in FIG. 1, the inorganic filter 10 includes an inorganic particle layer 12 containing inorganic particles and an inorganic binder, and a support 14 that supports the inorganic particle layer 12.

The inorganic particle layer 12 is a part that functions as a filtration membrane.
As shown in FIG. 2, the inorganic particle layer 12 is a layer containing inorganic particles 16 having an average particle diameter of 0.01 μm or more and an inorganic binder 18, and is laminated on the support 14. Is formed.
The inorganic binder 18 is at least one selected from the group consisting of aluminum phosphate, sodium silicate, and aluminum chloride. The material for the inorganic binder will be described in detail later.

Further, as shown in the figure, the inorganic particle layer 12 has voids in the layer. The porosity of the inorganic particle layer 12 is 10 to 70%. By forming voids at a predetermined porosity, adjacent voids communicate with each other, and a minute passage penetrating in the thickness direction of the inorganic particle layer 12 is formed. Since the inorganic particle layer 12 has a large number of such minute passages, solid particles larger than the passages can be separated from an object to be filtered in which a solid is mixed in a liquid or a gas.

The support 14 is a part that supports the inorganic particle layer 12, and the inorganic particle layer 12 is laminated on one main surface.
As shown in FIG. 2, the support body 14 has a plurality of through passages 14a penetrating in the thickness direction. The through passage 14 a is a passage for allowing the material to be filtered that has passed through the inorganic particle layer 12 to pass through the surface opposite to the inorganic particle layer 12.

There is no particular limitation on the size of the through-passage 14a, the number of the through-passage 14a, and the like. The size and the number of the through-passage 14a can be supported without suppressing the flow of the filtration object that has passed through the inorganic particle layer 12. That's fine. From the above viewpoint, the diameter of the through passage 14a is preferably 50 μm to 1000 μm, and the aperture ratio is preferably 20% to 80%.

The thickness of the support 14 is not particularly limited as long as it can properly support the inorganic particle layer and can provide the required flexibility, but is preferably 50 μm to 5000 μm.

As described above, filters made of inorganic materials are excellent in heat resistance and corrosion resistance. However, a ceramic filter made of a ceramic porous body has a problem that it cannot be processed such as being bent into a desired shape, or is susceptible to impact such as being broken by dropping. In addition, since the alumina membrane filter basically uses a straight tubular micropore as a filtration flow path, there is a problem that fine particles in the object to be treated are easily clogged in the micropore and the filtration flow rate is reduced. there were.

On the other hand, the inorganic filter of the present invention has an inorganic particle layer containing inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder, and the inorganic binder is aluminum phosphate. , At least one selected from the group consisting of sodium silicate and aluminum chloride, and has a structure in which the porosity of the inorganic particle layer is 10 to 70%.
Since the inorganic filter of the present invention binds minute inorganic particles with an inorganic binder, it is resistant to bending, dropping, etc., and has excellent flexibility. Moreover, the inorganic filter of this invention adjusts the ratio of the space | gap produced by binding a fine inorganic particle, makes the adjacent space | gap communicate, and is used as the channel | path for filtration. For this reason, since the sizes of the passages vary, clogging is unlikely to occur. In addition, since each gap communicates with several gaps, a branched passage is formed. Therefore, even if one part of the passage is clogged, the other part of the branch can maintain the communication state, and clogging is difficult to occur. Therefore, it can suppress that the filtration flow volume falls by clogging, and is excellent in filtration amount.

Here, when the porosity of the inorganic particle layer is less than 10%, the flexibility is lowered, and clogging is easily caused and the amount of filtration is lowered. On the other hand, when the porosity is more than 70%, the adhesion between the inorganic particles is deteriorated, and it becomes easy to break, so that the flexibility is lowered. Therefore, the porosity of the inorganic particle layer of the inorganic filter of the present invention is 10% or more and 70% or less.
The porosity may be determined by the diameter of the particles contained in the material to be filtered, the required filtration amount, etc., but from the above viewpoint, it is preferably 15% to 60%, more preferably 20% to 50%. preferable.

In the present invention, the porosity is defined to be measured by the following method.
First, the inorganic particle layer to be measured is accurately cut into a size of 1 mm ³ with a microtome. Next, the cut inorganic particle layer was gradually increased to a pressurization amount of 0 to 200 MPa using an Autopore IV 9500 manufactured by Shimadzu Corporation, and a diameter of 10 ⁻⁵ mm to 10 ⁻¹ mm (10 nm to 100 μm) is measured in total. For all the voids thus obtained, the void amount X (mm ³ ) is calculated from the diameter D (mm) and the quantity n. That is calculated as ^{X = Σ (πnD 3/6} ).
Accordingly, the porosity (%) is calculated by X (mm ³ ) ÷ 1 (mm ³ ) × 100%.

The thickness of the inorganic particle layer is preferably 10 μm to 5000 μm. By setting the thickness of the inorganic particle layer to 10 μm or more, it is preferable in that filtration can be performed with high accuracy. Moreover, it is preferable at the point which can increase the filtration flow volume by making the thickness of an inorganic particle layer into 5000 micrometers or less.

Here, in the example shown in FIG. 1, the inorganic particle layer 12 is laminated on one main surface of the support 14, but the inorganic filter of the present invention is not limited thereto. For example, like the inorganic filter 20 shown in FIG. 3, the inorganic particle layer 12 may be laminated on both main surfaces of the support 14. That is, the inorganic filter 20 is obtained by laminating the inorganic particle layer 12, the support 14, and the inorganic particle layer 12 in this order.
Or it is good also as a structure which laminated | stacked the support body on both main surfaces of the inorganic particle layer.
Or it is good also as an inorganic filter comprised only with the inorganic particle layer 12, like the inorganic filter 22 shown in FIG.
In addition, the structure which laminates | stacks an inorganic particle layer on a support body is preferable at the point which can prevent a crack etc. of an inorganic particle layer more suitably, and can improve flexibility.

In addition, the inorganic filter 10 shown in FIG. 1 has a configuration in which an inorganic particle layer and a support are laminated. However, the present invention is not limited to this, and the inorganic filter layer may be filled in the through-holes of the support. Good.
The inorganic filter 24 shown in FIG. 5 includes a support 14 having a large number of through holes 14b, and inorganic particle layers 12a filled in the through holes 14b.
The inorganic particle layer 12a is the same as the inorganic particle layer 12 except that it is formed in each through-hole 14b of the support.

The through hole 14b of the support 14 is for holding the inorganic particle layer 12a therein. There are no particular limitations on the size, shape, and the like of the through hole 14b as long as the inorganic particle layer 12a can be appropriately held and function as a filtration membrane. From the above viewpoint, the diameter of the through hole 14b is preferably 0.1 mm to 5.0 mm.

In addition, when using the inorganic filter of this invention for filtration operation, in order to prevent a crack etc. of an inorganic filter, you may laminate | stack a reinforcement member on the at least one main surface of an inorganic filter.
FIG. 6 is a schematic cross-sectional view showing an example of a filter structure having the inorganic filter and the reinforcing member of the present invention.
In addition, since the inorganic filter 24 in the filter structure 30 shown in FIG. 6 is the inorganic filter 24 shown in FIG. 5, the description is abbreviate | omitted.

As shown in FIG. 6, the filter structure 30 has a configuration in which reinforcing members 32 are laminated on the main surfaces on both sides of the inorganic filter 24.
The reinforcing member 32 is a plate-like member having a large number of through passages 32a. The through passage 32 a is a passage for supplying the material to be filtered to the inorganic filter 24, and is a passage for allowing the material to be filtered filtered by the inorganic filter 24 to pass therethrough.
As described above, the reinforcing member 32 is arranged on both surfaces of the inorganic filter 24 and the inorganic filter 24 is sandwiched between the reinforcing members 32, so that when the pressure is increased and the filtration operation is performed, the inorganic filter is applied by the applied pressure. 24 can be prevented from cracking.

The material of the reinforcing member 32 is not particularly limited as long as it can prevent cracking of the inorganic filter during the filtration operation, and various materials such as metal and non-metal can be used. Specific examples of the material of the reinforcing member 32 include, for example, iron, aluminum, stainless steel, zinc, copper, brass, and titanium as the metal. Examples of the resin include polypropylene, polyethylene, PET, polycarbonate, polyvinyl chloride, and CFRTP (carbon fiber composite thermoplastic resin).

The thickness of the reinforcing member 32 is not particularly limited as long as the inorganic filter can be prevented from cracking, but is preferably 0.1 mm to 10 mm.
Moreover, there is no limitation in particular in the magnitude | size of the penetration path 32a formed in the reinforcement member 32, the number to form, etc., The flow of a to-be-filtered material should not be suppressed, and the crack of an inorganic filter should just be prevented. From the above viewpoint, the diameter of the through passage 32a is preferably 0.35 mm to 20.0 mm, and the aperture ratio is preferably 9 to 60%.
The shape of the opening of the through passage 32a is not particularly limited, and various shapes such as a circular shape, a triangular shape, a quadrangular shape, a rhombus, a polygonal shape, an elliptical shape, and a cross shape can be used.

The fixing method of the inorganic filter 24 and the reinforcing member 32 is not particularly limited. For example, bonding with an adhesive, screwing, binding with the reinforcing member using the inorganic binder 18 of the inorganic filter 24, and the like. Various fixing methods are available.

In the example shown in FIG. 6, the reinforcing members 32 are arranged on both surfaces of the inorganic filter 24, but the present invention is not limited to this, and the arrangement is made only on one main surface side of the inorganic filter 24. Also good.
Further, the filter structure 30 shown in FIG. 6 has the inorganic filter 24 in which the inorganic particle layer 12a is formed in the through-hole 14b of the support 14, but is not limited thereto, and the inorganic structure of the present invention is not limited thereto. Applicable to any filter.

Next, materials, formation methods and the like will be described for each configuration of the inorganic filter of the present invention.

[Support]
The material of the support that the inorganic filter of the present invention has is not particularly limited, and various materials such as metal and nonmetal can be used. The material of the support may be appropriately selected according to the purpose of use and the object to be filtered, and from the viewpoints of heat resistance, corrosion resistance, flexibility, and the like.
The support may be a plate-like (film-like) member of the material formed with a large number of through passages (through-holes), or a braided wire of the material is formed in a net shape. It may be a thing (mesh).

When the support is made into a mesh, the diameter of the wire is preferably 10 μm to 1000 μm. The aperture ratio is preferably 20% to 80%.

Specific examples of the metal used as the material for the support include aluminum, gold, silver, copper, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony.
Among these, aluminum (aluminum alloy) is preferable because it is excellent in workability, strength, and flexibility.
Specific examples of the resin used as the material for the support include glass, carbon, nylon, PET, PEN, acrylic, vinylon, polyolefin, and polyurethane.

[Inorganic particle layer]
As described above, the inorganic particle layer is a layer containing inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder. The porosity of the inorganic particle layer is 10 to 70%.
Next, the inorganic particles and the inorganic binder contained in the inorganic particle layer will be described in detail.

<Inorganic particles>
The inorganic particles contained in the inorganic particle layer are particles having an average particle diameter of 0.01 μm or more.
The kind of the inorganic particles is not particularly limited, and conventionally known oxides (for example, metal oxides), nitrides (for example, metal nitrides), hydroxides (for example, metal hydroxides), inorganic salts (For example, phosphate, carbonate, sulfate, etc.), carbide (eg, metal carbide), metal, or the like can be used.
Here, the average particle diameter means an average value of the particle diameters of the inorganic particles. In the present invention, a 50% volume cumulative diameter (D50) measured by a light scattering method using a laser diffraction particle size distribution measuring device. ).

The average particle diameter of the inorganic particles is preferably 0.01 to 100 μm, more preferably 0.05 to 100 μm, and particularly preferably 0.1 to 50 μm from the viewpoints of flexibility, filtration amount, workability, strength, and the like. .

Specific examples of the inorganic particles include aluminum oxide (alumina), aluminum nitride, boron nitride, silicon nitride, silicon oxide, silicon carbide, titanium oxide, titanium nitride, zirconium oxide, yttrium oxide, and calcium phosphate. , Graphite, tungsten carbide, silicon parbite, aluminum hydroxide, calcium hydroxide, calcium carbonate, calcite, calcium carbonate, light calcium carbonate, heavy calcium carbonate, ultrafine calcium carbonate, gypsum, calcium sulfate, marble, Barium sulfate, barium carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, strontium carbonate, gold, silver, aluminum, kaolin clay, calcined clay, talc, sericite, optical glass, glass beads, etc. , May be used those either alone, or in combination of two or more.

In the present invention, from the viewpoint of ease of particle size control due to high versatility, the inorganic particles include alumina, aluminum nitride, boron nitride, silicon oxide, silicon nitride, titanium oxide, titanium nitride, zirconium oxide, and oxidation. It is preferable to use yttrium, calcium phosphate, graphite, tungsten carbide, and silicon carbide.

In the present invention, two or more kinds of particles or two or more kinds of particles having an average particle diameter may be used in combination as the inorganic particles.
By using particles having different types and average particle sizes in combination, the strength and flexibility of the inorganic filter can be improved.

In the present invention, the shape of the inorganic particles is not particularly limited. For example, the shape is spherical, polyhedral (for example, icosahedron, dodecahedron, etc.), cubic, tetrahedral, or uneven on the surface. It may be any shape having a plurality of convex protrusions (hereinafter also referred to as “compete shape”), a plate shape, a needle shape, or the like.

<Inorganic binder>
The inorganic binder contained in the inorganic particle layer contains at least one selected from the group consisting of aluminum phosphate, sodium silicate and aluminum chloride.

(Aluminum phosphate)
Examples of the aluminum phosphate include not only aluminum phosphate in a narrow sense but also aluminum metaphosphate, aluminum orthophosphate, and aluminum polyphosphate in addition to aluminum phosphate.
The aluminum phosphate can be obtained by reacting commercially available phosphoric acid and commercially available aluminum sulfate (or aluminum hydroxide, aluminum chloride, and a mixture thereof) in the presence of water. Furthermore, since aluminum chloride is considered to have a role of causing the reaction of aluminum hydroxide to proceed catalytically, it is preferable to add both aluminum hydroxide and aluminum chloride in the above reaction, and the amount of aluminum chloride is water. It is preferably 5 to 10% with respect to the amount of aluminum oxide. When neutralization of the reactant is necessary, a sodium hydroxide solution can be used, and aluminum sulfate may be produced by reacting sulfuric acid and alumina.

(Sodium silicate)
The above-mentioned sodium silicate is also called sodium silicate or water glass, and Na ₂ SiO _3, which is a sodium salt of metasilicate, is commonly used. In addition, Na ₄ SiO ₄ , Na ₂ Si ₂ O ₅ , Na ₂ Si ₄ O ₉ or the like can also be used.
The sodium salt of metasilicic acid can be obtained by melting silicon dioxide with sodium carbonate or sodium hydroxide.

(Aluminum chloride)
The aluminum chloride may be any of anhydrous aluminum chloride, aluminum chloride hexahydrate, and polyaluminum chloride (a polymer of basic aluminum chloride formed by dissolving aluminum hydroxide in hydrochloric acid).

Regarding the content ratio of the inorganic binder and the inorganic particles in the inorganic particle layer, the inorganic binder is preferably contained in an amount of 5 to 100 parts by mass with respect to 100 parts by mass of the inorganic particles. More preferred.
Furthermore, the inorganic particle layer may contain other compounds in addition to the inorganic binder and the inorganic particles. Examples of other compounds include a dispersant and a reaction accelerator.

<Method for forming inorganic particle layer>
In the present invention, the method for forming the inorganic particle layer is not particularly limited. For example, the coating liquid (composition) containing the inorganic particles and the inorganic binder is screen printed on the surface of the support. For example, the methods described in [0021] to [0023] of International Publication No. 2012/133173 may be used.

Here, the porosity of the inorganic particle layer can be adjusted by adjusting the ratio of the inorganic particles and the inorganic binder in the coating solution.
Further, when forming the inorganic particle layer, after forming a coating liquid containing the inorganic particles and the inorganic binder on the surface of the support, first, coating is performed by applying dry air at a low temperature. The proportion of voids in the inorganic particle layer after firing can also be adjusted by removing (evaporating) some of the moisture in the film, concentrating it, and then forming it by heating to a predetermined temperature and firing. can do.

In the case where the inorganic particle layer is formed in the through hole of the support as in the inorganic filter shown in FIG. 5, after applying the coating liquid on the support, pressure is applied from the coating liquid side to apply the coating liquid. Can be formed by press-fitting into the through hole and drying.

Moreover, when it is set as the structure which does not have a support body like the inorganic filter shown in FIG. 4, for example, the printing liquid containing the said inorganic particle and the said inorganic binder is screen-printed on the surface of a temporary support body etc. After coating, the inorganic particle layer is formed by drying, firing and curing. Then, it can form by peeling a temporary support body and an inorganic particle layer.
Examples of the material for the temporary support include metal substrates that do not contain aluminum such as copper, iron, and titanium, or PET, PPS, PI, PTFE, PAI, and silicon resin.

The viscosity of the coating solution containing the inorganic particles and the inorganic binder is preferably 100 cP to 50000 cP.
By setting the viscosity of the coating solution in the above range, the inorganic particle layer can be formed on the support without the coating solution flowing down into the through path when the coating solution is applied onto the support.
Moreover, also when forming an inorganic particle layer in the through-hole of a support body, an inorganic particle layer can be formed in a through-hole, without a coating liquid flowing down from a through-hole.

The inorganic filter of the present invention has been described in detail above. However, the present invention is not limited to the above-described example, and various improvements and modifications may be made without departing from the scope of the present invention. It is.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

[Example 1]
As Example 1, an inorganic filter having the configuration shown in FIG.

[Support]
As a support, a support A obtained by methanol degreasing of an aluminum mesh having a size of 100 × 100 mm, a mesh diameter of 100 μm, and a wire diameter of 100 μm (manufactured by KUBA Co., Ltd.) was used.

[Inorganic particle layer]
The inorganic particle layer coating liquid A prepared at the following composition ratio is applied to the entire surface of one of the main surfaces of the support so that the thickness after drying and baking is 40 μm, and heated at 220 ° C. for 30 minutes. Then, drying and baking were performed to form an inorganic particle layer, and an inorganic filter was produced.
The inorganic binder of the inorganic particle layer obtained by baking the coating liquid A is aluminum phosphate.
Moreover, when the porosity of the inorganic particle layer was measured, the porosity was 20%.

<Preparation of coating liquid A>
A binder liquid A having the following composition was prepared.
・ Phosphoric acid 85% (Wako Pure Chemical Industries, Ltd.) 48g
・ Aluminum hydroxide (Wako Pure Chemical Industries, Ltd.) 11g
・ Water 41g

Next, 100 g of aluminum oxide (manufactured by Showa Denko KK: Al-160SG-3, average particle size of 0.1 μm) as inorganic particles was added to the binder liquid A and stirred to prepare a coating liquid A.

[Example 2]
An inorganic filter was produced in the same manner as in Example 1 except that the average particle diameter of the inorganic particles was changed to 1.5 μm.
When the porosity of the produced inorganic particle layer was measured, the porosity was 30%.

[Example 3]
Except for changing the average particle size of the inorganic particles to 5 μm and changing the support to a support B of an aluminum mesh (made by KURAA Co., Ltd.) having a mesh diameter of 120 μm and a wire diameter of 100 μm, the same as in Example 1. An inorganic filter was produced.
When the porosity of the produced inorganic particle layer was measured, the porosity was 55%.

[Example 4]
Other than changing the inorganic particles to calcium phosphate (manufactured by Junsei Co., Ltd .: calcium hydrogen phosphate dihydrate # 84110-0401, average particle size 1.5 μm) and changing the inorganic binder to sodium silicate Produced an inorganic filter in the same manner as in Example 2.
When the porosity of the produced inorganic particle layer was measured, the porosity was 20%.
In addition, in order to use an inorganic binder as sodium silicate, it replaced with the binder liquid A and used the binder liquid B of the composition ratio shown below.

<Preparation of binder liquid B>
A binder liquid B having the following composition was prepared.
・ No. 3 sodium silicate undiluted solution (Toyama Chemical Co., Ltd.) 100g
・ Water 10g

[Example 5]
Except that the inorganic particles were changed to zirconium oxide (manufactured by Junsei Chemical Co., Ltd .: zirconium dioxide # 53130-1501, average particle size 1.5 μm) and the inorganic binder was changed to aluminum chloride, the same procedure as in Example 2 was performed. An inorganic filter was produced.
When the porosity of the produced inorganic particle layer was measured, the porosity was 35%.
In addition, in order to make an inorganic binder into aluminum chloride, it replaced with the binder liquid A and used the binder liquid C of the composition ratio shown below.

<Preparation of binder liquid C>
A binder liquid C having the following composition was prepared.
・ 35% hydrochloric acid (Wako Pure Chemical Industries, Ltd.) 80g
・ Aluminum hydroxide (Wako Pure Chemical Industries, Ltd.) 10g
・ Water 10g

[Example 6]
An inorganic filter was produced in the same manner as in Example 2 except that the support was not provided and the thickness was different.
That is, the coating liquid A was coated on a temporary support so that the thickness after drying and firing was 500 μm, heated at 220 ° C. for 45 minutes, dried and fired to form an inorganic particle layer, and then inorganic The particle layer was peeled from the temporary support to produce an inorganic filter.
When the porosity of the produced inorganic particle layer was measured, the porosity was 30%.

[Comparative Example 1]
An inorganic filter was produced in the same manner as in Example 2 except that the porosity was 8%.

[Comparative Example 2]
An inorganic filter was produced in the same manner as in Example 2 except that the porosity was 75%.

[Comparative Example 3]
As Comparative Example 3, a ceramic filter having an average pore diameter of 5 μm, a porosity of 9%, and a thickness of 2000 μm was prepared.

[Comparative Example 4]
As Comparative Example 4, a ceramic filter similar to Comparative Example 3 was prepared except that the average pore diameter was 1 μm and the porosity was 6%.

[Comparative Example 5]
As Comparative Example 5, a ceramic filter similar to Comparative Example 3 was prepared except that the average pore diameter was 0.2 μm and the porosity was 8%.

[Comparative Example 6]
As Comparative Example 6, an alumina membrane filter produced by the method described in Example 2 of Patent Document 2 (Japanese Patent Laid-Open No. 2009-50773) was prepared.
The thickness was 30 μm, the average pore diameter was 0.06 μm, and the porosity was 30%.

[Evaluation]
The produced inorganic filter, ceramic filter, and alumina membrane filter (hereinafter collectively referred to as a filter) were measured for flexibility, presence or absence of clogging, and fractionation by the following methods. These results are shown in Table 1.

<Flexibility>
The prepared filter was applied to an iron rod having a diameter of 10 mm and bent at 30 ° to observe whether or not breakage occurred. A was given when no cracks were observed, B was given when partly broken, and C was given when broken.

<Fractionation>
In order to verify the size fractionability of the produced filter, the following aqueous solution 10 g was filtered with each filter.
As an aqueous solution, 50 nm, 500 nm, and 1 μm diameter silica particles dispersed in water at a concentration of 10% by mass were used.
The fraction was calculated from the change in weight of the aqueous solution before and after filtration. As the fractionation rate is closer to 100%, particles in the aqueous solution are removed by the filter.

<Clogging>
During the fractionation test, the filter clogging was also evaluated. The amount of filtration L1 per minute immediately after the start of filtration and the amount of filtration L2 per minute 3 minutes after the start of filtration are measured, respectively, and when L2 / L1 is 95% or more, A, 70% or more and 95% The case of less than B was designated as B, and the case of less than 70% was designated as C.

From the results shown in Table 1, it has an inorganic particle layer containing inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder, and the inorganic binder is composed of aluminum phosphate, sodium silicate and Examples 1 to 6 of the present invention, which is at least one selected from the group consisting of aluminum chloride and the porosity of the inorganic particle layer is 10 to 70%, are good results in both flexibility and clogging. I understand that.
On the other hand, it can be seen that Comparative Example 1 in which the porosity of the inorganic particle layer is less than 10% is likely to be clogged because the porosity is low, and the filtration flow rate is reduced. Moreover, since the adhesiveness of inorganic particle layers falls in the comparative example 2 with the porosity of an inorganic particle layer exceeding 70%, it turns out that it becomes easy to break and it is inferior to flexibility.
It can also be seen that Comparative Examples 3 to 5 which are ceramic filters are inferior in flexibility. Moreover, it turns out that clogging generate | occur | produces the comparative example 6 which is an alumina membrane filter, and is inferior to the filtration amount.
Further, it can be seen from the comparison between Example 2 and Example 6 that having a support improves the flexibility.
The effects of the present invention are clear from the above results.

10, 20, 22, 24

Inorganic filter

12, 12a Inorganic particle layer 14 Support 14a Through passage 14b Through hole 16 Inorganic particle 18 Inorganic binder

Claims

Having an inorganic particle layer containing inorganic particles having an average particle diameter of 0.01 μm or more and an inorganic binder;
The inorganic binder is at least one selected from the group consisting of aluminum phosphate, sodium silicate and aluminum chloride;
An inorganic filter in which the porosity of the inorganic particle layer is 10 to 70%.
Having a support having a plurality of through holes penetrating in the thickness direction;
The inorganic filter according to claim 1, wherein the inorganic particle layer is formed in a through hole of the support.
A support having a plurality of passages penetrating in the thickness direction;
The inorganic filter according to claim 1, wherein the inorganic particle layer is laminated on the support.
The inorganic filter according to claim 3, wherein the inorganic particle layer is laminated on both surfaces of the support.
The inorganic filter according to any one of claims 2 to 4, wherein a material of the support is aluminum.
The inorganic filter according to any one of claims 1 to 5, wherein the inorganic particles are at least one selected from the group consisting of oxides, nitrides, hydroxides, inorganic salts, and carbides.
The inorganic filter according to any one of claims 1 to 6, wherein the inorganic particle layer has a thickness of 10 袖 m to 5000 袖 m.