Absorbing material

Abstract

To provide an absorbing material that exhibits superior absorption performance and high strength.SOLUTION: An absorbing 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 absorbent 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 absorbents with even more specialized porous structures (Patent Document 1). However, few of the existing diatomaceous earth products are able to achieve both high absorption performance and high strength, and there are no diatomaceous earth products that are particularly excellent in both absorption performance and strength, so existing 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 absorbent material having excellent absorption 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 smaller pore size and a denser porous structure than the first layer, not only has excellent absorption performance but also excellent strength, and that such a structure is useful as an absorbent 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 absorbent material comprising a first porous structure made of diatomaceous earth, characterized in that the absorbent 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 absorbent 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 absorbent material according to [1], wherein the diatomaceous earth is Wakkanai diatomaceous earth. [4] The absorbent 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 absorbent material according to [1], wherein the porous structures are all made of a sintered body. [6] A method for manufacturing an absorbent 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 absorbent material of the present invention has excellent absorption 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 absorbent material of the present invention is a structure including a first layer having a porous structure (first porous structure) made of diatomaceous earth, characterized in that a second layer made of the diatomaceous earth and having a dense porous structure (second porous structure) in which the pore size of the porous structure is smaller and denser than that of 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 an absorbent material either as it is or after processing. [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) Water vapor adsorption isotherms were measured using a high-precision gas / vapor adsorption analyzer. For all measurements, samples were pretreated by heating at 100°C for 4 hours and vacuum degassing to remove adsorbed gases. Water vapor adsorption isotherms were measured at an adsorption temperature of 25°C using the volumetric method up to a relative pressure of approximately 0.9.

[0020] The nitrogen gas adsorption specific surface area of ​​the example product is 59.3 m 2 / g. The water vapor gas adsorption specific surface area of ​​the example product is 145m 2 / g. The nitrogen gas adsorption specific surface area of ​​the comparative example is 12.6 m 2 / g. The water vapor gas adsorption specific surface area of ​​the comparative example was 61.6 m 2 / g. The comparative example products were inferior in absorption performance to the example products. [Industrial Applicability]

[0021] The structure of the present invention is suitable for use as an absorbent material. [Explanation of symbols]

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

Claims

1. An absorbent material comprising a first porous structure made of diatomaceous earth, characterized in that the absorbent material further comprises a second porous structure made of the diatomaceous earth, which has a smaller pore diameter and is denser than the first porous structure.

2. 2. The absorbent 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 absorbent material according to claim 1, wherein the diatomaceous earth is Wakkanai diatomaceous earth.

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

5. 2. The absorbent material according to claim 1, wherein said porous structures are all made of a sintered body.

6. A method for manufacturing an absorbent 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 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 more dense 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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