Air purifying material

Abstract

To provide an air purifying material that exhibits superior air cleaning performance and high strength.SOLUTION: An air purifying material includes a first porous structure composed of diatomaceous earth, and further includes a second porous structure composed of the diatomaceous earth and having a smaller pore diameter and being denser than the first porous structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air freshening material comprising diatomaceous earth. [Background technology]

[0002] Conventionally, diatomaceous earth has been molded and used for bath mats, etc. In recent years, the use of mesopore diatomaceous earth, also known as Wakkanai diatomaceous earth, has been developed, and it is used, for example, as a building material such as a wall material.

[0003] In recent years, research has been progressing on air purifying materials with even more specialized porous structures (Patent Document 1). However, few conventional diatomaceous earth products are able to achieve both air purification performance and strength, and there are no diatomaceous earth products that are particularly excellent in both air purification performance and strength, and conventional diatomaceous earth products are still not satisfactory. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-173401 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an air cleaning material having excellent air cleaning performance and strength. [Means for solving the problem]

[0006] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that a structure including a first layer having a porous structure made of diatomaceous earth, with a second layer made of the same diatomaceous earth and having a dense porous structure formed on top of the first layer, the second layer having a porous structure with a smaller pore size and a denser structure than the first layer, not only has excellent air purification performance but also has excellent strength, and that such a structure is useful as an air purification material and can solve all of the above-mentioned conventional problems at once. Furthermore, after obtaining the above findings, the inventors of the present invention conducted further studies and completed the present invention.

[0007] That is, the present invention relates to the following inventions. [1] An air purifying material comprising a first porous structure made of diatomaceous earth, characterized in that the air purifying material further comprises a second porous structure made of the diatomaceous earth, the second porous structure having a smaller pore size and being denser than the first porous structure. [2] The air purifying material according to [1], wherein the pore sizes of the porous structures are different and a third porous structure made of the diatomaceous earth is further formed. [3] The air purifying material according to [1], wherein the diatomaceous earth is Wakkanai diatomaceous earth. [4] The air purifying material according to [1], wherein the porosity of the first porous structure is 50% or more, and the porosity of the second porous structure is 10% or less. [5] The air purifying material according to [1], wherein the porous structure is made of a fired body. [6] A method for producing an air purifying material using a slurry containing diatomaceous earth powder, characterized in that a combustible substance is used to form a first layer having a porous structure made of the diatomaceous earth and a second layer made of the diatomaceous earth and having a dense porous structure in which the pore size of the porous structure is smaller and more dense than that of the first layer. [7] The manufacturing method according to [6], wherein the combustible material is a polymer. [8] The manufacturing method according to [6], wherein the slurry is placed in a mold having a removable inner frame and then fired to form the first layer and the second layer. [Effects of the Invention]

[0008] The air purifying material of the present invention has excellent air purifying performance and exhibits the effect of being excellent in strength. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 shows a mold having a plurality of removable inner frames used in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The air purifying material of the present invention is a structure including a first layer having a porous structure (first porous structure) made of diatomaceous earth, and is characterized in that a second layer made of the diatomaceous earth and having a dense porous structure (second porous structure) that is smaller in pore size and denser than the first layer is provided on the first layer.

[0011] The porous structure is not particularly limited in terms of pore size, etc., and any known porous structure may be used. In the present invention, it is preferable that the pore sizes of the porous structures are different and that a third layer (third porous structure) made of diatomaceous earth is further provided. In the present invention, it is also preferable that the diatomaceous earth is Wakkanai diatomaceous earth. In the present invention, it is also preferable that the porosity of the first layer is 50% or more and the porosity of the second layer is 10% or less. Within these preferred ranges, the absorbency and strength derived from the porous structure can be improved.

[0012] In the present invention, it is preferable that the structure is a fired body, and such a preferred structure can be easily obtained by a method for manufacturing a structure using a slurry containing diatomaceous earth powder, in which a combustible substance is used to form a first layer having a porous structure made of diatomaceous earth and a second layer made of diatomaceous earth and having a dense porous structure in which the pore size of the porous structure is smaller and the second layer is denser than the first layer.

[0013] In the present invention, the combustible material is preferably a polymer. This preferred range allows for easier formation of the structure by firing. Furthermore, in the present invention, the first layer and the second layer are preferably formed by placing the slurry in a mold having a removable inner frame and firing the mixture. The slurry is not particularly limited as long as it does not impair the present invention, but it preferably contains a binder in addition to the diatomaceous earth. Suitable examples of the binder include a mixture of Kibushi clay, silicic anhydride, and an appropriate amount of water, or rhyolitic natural glass powder added to Wakkanai diatomaceous earth. When using such a preferred binder, the slurry is preferably prepared by blending and kneading, for example, 10 parts diatomaceous earth with 1 to 3 parts by weight, preferably 2 parts by weight, Kibushi clay, 1 to 3 parts by weight, preferably 1 part by weight, silicic anhydride, and an appropriate amount of water, or 1 to 3 parts by weight, preferably 1 part by weight, of rhyolitic natural glass powder.

[0014] In the present invention, the structure is used as it is or after processing as an air purifying material. [Example]

[0015] Example 1 1. Preparation of slurry A slurry was prepared by mixing 10 parts by weight of diatomaceous earth, 2 parts by weight of Kibushi clay, 1 part by weight of silicic anhydride, an appropriate amount of water, and 1 part by weight of rhyolitic natural glass powder with combustible materials. The slurry was placed in the mold shown in Figure 1 with the following combustible material amounts, and fired.

[0016] [Combined amount of flammable materials] Area 1: Slurry containing 0% by weight of combustible material (polymer) Area 2: Slurry of 10% by weight of combustible material (polymer) Area 3: Slurry of 20% by weight of combustible material (polymer) Area 4: Slurry containing 30% by weight of combustible material (polymer) Zone 5: Slurry of 40% by weight of combustible material (polymer)

[0017] The firing conditions were that the temperature inside the firing kiln was raised to around 1100°C and maintained for approximately 2 hours, after which the temperature increase was stopped and the product was slowly cooled in the firing kiln and removed. The porosity (air void ratio) of regions 1 to 5 of the resulting fired body (structure) was examined, and it was found to be 10% for region 1, 20% for region 2, 30% for region 3, 40% for region 4, and 50% for region 5.

[0018] (Test Example 1) The structure (specimen) obtained in Example 1 was left to stand under conditions of 20°C and 50% RH humidity until it reached a constant weight, and the bulk density was measured. Seven specimens were used for each sample, and the average of the measured values ​​was obtained. In addition, the bending strength of some of the specimens was measured by a three-point bending test. As a comparative example, the bending strength of a structure consisting of only region 1 was measured. The bending strength of the comparative example was 2.8 Nmm -2 The bending strength of the structure of Example 1 was 3.5 Nmm-2.

[0019] (Test Example 2) The product of the example was placed in a bag made of a material that does not easily adsorb or desorb malodorous substances, such as polyvinyl fluoride, and the bag was sealed and filled with air. Malodorous gas was added so that the initial concentration was set within the detector tube measurement concentration range, and the fan was operated. The gas concentration in the bag was measured over time with the detector tube, and the time required for 90% of the malodorous substances to be removed was calculated from these measurements. The effectiveness was judged based on whether the time required for 90% of the malodorous substances to be removed was within 10 hours when the test was conducted in a 10L container.

[0020] The removal time of the example product was 7 hours, while the comparative example product was 5 hours, showing an inferior air purification function to the example product. [Industrial Applicability]

[0021] The structure of the present invention is suitable for use in air purifying materials. [Explanation of symbols]

[0022] 1 area 1 2 area 2 3 area 3 4 area 4 5 area 5

Claims

1. An air purifying material comprising a first porous structure made of diatomaceous earth, characterized in that the air purifying material further comprises a second porous structure made of the diatomaceous earth, the second porous structure having a smaller pore diameter and being denser than the first porous structure.

2. 2. The air purifying material according to claim 1, wherein the pore sizes of the porous structures are different from each other and a third porous structure made of the diatomaceous earth is further formed.

3. 2. The air purifying material according to claim 1, wherein the diatomaceous earth is Wakkanai diatomaceous earth.

4. 2. The air purifying material according to claim 1, wherein the porosity of the first porous structure is 50% or more, and the porosity of the second porous structure is 10% or less.

5. 2. The air purifying material according to claim 1, wherein each of said porous structures is made of a sintered body.

6. A method for producing an air purifying material using a slurry containing diatomaceous earth powder, comprising using a combustible substance to form a first layer having a porous structure made of the diatomaceous earth and a second layer having a dense porous structure made of the diatomaceous earth, the pore size of the porous structure being smaller and denser than that of the first layer.

7. 7. The method of claim 6, wherein the combustible material is a polymer.

8. 7. The method according to claim 6, wherein the slurry is placed in a mold having a removable inner frame and then fired to form the first layer and the second layer.

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