JP7258734B2 - Porous body with excellent water absorption - Google Patents

Description

TECHNICAL FIELD The present invention relates to a porous body excellent in water absorption used in an environment where dew condensation is likely to occur. The present invention also relates to a method for manufacturing this porous body.

2. Description of the Related Art Conventionally, there has been known a technique of absorbing condensed water by using a porous body in order to prevent generation and scattering of condensed water in an environment of high humidity and easy to condense. For example, Cited Document 1 describes a method for producing an aluminum porous body that absorbs excessive moisture with high efficiency even in a humid environment where dew condensation is likely to occur, thereby suppressing the formation of dew condensation on the substrate surface. In Cited Document 1, fine aluminum particles having a particle diameter of 300 μm or less, which are pulverized by mechanical means to form unevenness on the surface, are filled into a mold, and the surface of the fine aluminum particles is softened at a temperature range of 550 to 600° C. at a temperature of 30 to 60 kg/ Press with a pressure of cm ² . By adjusting the porosity of the aluminum porous body, the water absorption is improved.

JP 2009-57584 A

As described above, it is well known that the porous body has excellent water absorbency in a humid and dew-prone environment. In order to maintain this water absorbency, it is important to maintain the hydrophilicity of the surface of the porous body. Especially in the case of a porous body, the surface area of the base material is large, so the hydrophilicity of the surface is greatly affected. In particular, aluminum is known to have improved hydrophilicity by adding a large number of hydroxyl groups to its surface.

However, in environmental testing machines and the like, the temperature is generally controlled in the range of -20°C to 150°C. In such a temperature environment, for example, when an aluminum porous body is used, when the porous body is exposed to a high temperature (for example, about 150° C.) for a long period of time, the hydroxyl groups present on the surface are reduced and the hydrophilicity of the surface is lost. Sufficient water absorption cannot be maintained.

The present invention solves the above problems. Accordingly, an object of the present invention is to provide a porous body, particularly a porous body mainly composed of metal, which can maintain water absorbency even after being exposed to a high-temperature environment for a long period of time.

According to one aspect of the present invention, there is provided a porous body having pores and a substrate, the porous body comprising a hydrophilic component. The element is resistant to degradation of hydrophilicity when exposed to elevated temperatures. This porous body is preferably made of aluminum or an aluminum alloy.

According to one embodiment of the invention, the hydrophilic element comprises
a hydrophilic polymer layer covering at least part of the outer surface of the substrate;
At least one of zeolite and a silicate layer covering at least a portion of the outer surface of the substrate is preferred.

According to one embodiment of the present invention, the hydrophilic element preferably comprises a hydrophilic polymeric layer covering at least a portion of the outer surface of the substrate, wherein the hydrophilic polymeric layer comprises polyvinyl alcohol. It preferably contains (PVA).
According to one embodiment of the present invention, the hydrophilic element preferably comprises a hydrophilic polymeric layer covering at least a portion of the outer surface of the substrate, the hydrophilic polymeric layer containing silanol. It is preferable to contain.
Between the hydrophilic polymer layer and the substrate, there may be further provided a boehmite layer covering at least part of the outer surface of the substrate in direct contact therewith.

According to one embodiment of the present invention, it is preferred that the hydrophilic element contains zeolite and the porous body contains 0.1 mass % or more of zeolite based on the porous body. More preferably, the zeolite content is 0.2 to 6% by mass. More preferably, the zeolite is in the form of zeolite particles, and the zeolite particles are present at least on the pore surfaces of the substrate.
Also in this case, a boehmite layer covering at least part of the outer surface of the substrate may be provided.

According to one embodiment of the invention, the hydrophilic element preferably comprises a silicate layer. Furthermore, the porous body may further have a boehmite layer covering at least part of the outer surface of the substrate in direct contact between the substrate and the silicate layer. Furthermore, it may have a hydrophilic polymer layer on the silicate layer.

According to one embodiment of the invention, the porosity of the porous body is preferably between 20% and 90%.

According to another aspect of the present invention, there is provided a method for manufacturing an aluminum or aluminum alloy porous body. This manufacturing method is
preparing an aluminum powder or an aluminum alloy powder;
preparing zeolite powder with a mass of 0.1% or more of the mass of the aluminum powder or aluminum alloy powder;
mixing aluminum powder or aluminum alloy powder with the zeolite powder;
and sintering the mixed powder.

According to one embodiment of the invention, the weight of the zeolite powder is preferably 0.2-6% by weight of the weight of the aluminum powder or aluminum alloy powder.

According to one embodiment of the present invention, it is preferred to further comprise the step of treating the porous body with a silicate treatment or coating it with a hydrophilic polymer layer. Alternatively, there may be a step of coating the hydrophilic polymer layer after subjecting the porous body to silicate treatment. The porous body may be subjected to boehmite treatment before the porous body is subjected to silicate treatment or coating with a hydrophilic polymer layer.

According to another aspect of the present invention, there is provided a method for producing a porous aluminum or aluminum alloy body, the method comprising:
preparing an aluminum powder or an aluminum alloy powder;
sintering the aluminum powder or aluminum alloy powder;
and subjecting the sintered body to silicate treatment or coating with a hydrophilic polymer layer. The hydrophilic polymer layer preferably contains polyvinyl alcohol (PVA) and/or silanol.

According to one embodiment of the present invention, the porous body may be coated with a hydrophilic polymer layer after the silicate treatment. The porous body may be subjected to boehmite treatment before the porous body is subjected to silicate treatment or coating with a hydrophilic polymer layer.

According to one embodiment of the invention, the porosity of the sintered porous body is preferably between 20% and 90%.

According to one embodiment of the present invention, it is preferable that 70% or more of the aluminum powder or aluminum alloy powder has a particle size of 100 to 500 μm.

The porous body of the present invention can maintain hydrophilicity and have excellent water absorption even after being exposed to high temperatures such as about 150° C. or higher for a long time (for example, 500 hours or longer).

The invention and its advantages are described in more detail below with reference to the accompanying schematic drawings. The drawings show, for illustrative purposes, some non-limiting examples.

A schematic diagram of a cross section of a porous body according to a first embodiment of the present invention FIG. 2 is an enlarged schematic view of a cross section of the porous substrate of FIG. 1; Schematic of the cross section of the porous body by the 2nd Embodiment of this invention. Schematic of the cross section of the porous body by the 3rd Embodiment of this invention. Schematic diagram of a cross section of a porous body according to another embodiment of the present invention.

An object of the present invention is to provide a porous body that is used in an environment where dew condensation is likely to occur and that has excellent water absorption even after being exposed to high temperatures for a long period of time. As used herein, "high temperature" refers to a temperature of about 150° C. or higher (eg, about 180° C.), and "long time" refers to a time of, eg, 500 hours or longer. In addition, "excellent water absorption" is the ability to absorb condensed water instantly, and is judged by the ability to absorb water droplets such as condensed water within about 5 seconds after they adhere to or form on the "porous body surface". do. The term "water absorption" refers to a state in which the wetting angle of water droplets is approximately zero degrees, or a state in which water droplets are absorbed in pores. A "porous body surface" refers to the exterior surface of a porous body that does not include the interior surfaces that define the pores of the porous body.
Hereinafter, the surface inside the porous body that defines the pores will be referred to as the "inner surface", and the outer surface that does not include the "inner surface" will be referred to as the "porous body surface" or the "outer surface".

A porous body according to the present invention is a porous body having pores and a substrate, wherein the substrate comprises an element having hydrophilicity.
Specific embodiments of the porous body according to the present invention are described below.

First Embodiment FIG. 1 shows a schematic cross-sectional view of a first embodiment of the porous body of the present invention. This porous body 1 has a porous base 20 made of a sintered body of aluminum or an aluminum alloy, and a hydrophilic polymer layer 5 covering at least part of its outer surface. Optionally, there may be a boehmite layer 3 between the base 20 and the hydrophilic polymer layer 5 . An enlarged schematic view of a cross-section of porous base 20 is shown in FIG. The base 20 has a substrate 2 and cavities 4 . The substrate 2 is obtained by sintering any base powder of pure aluminum single powder, aluminum alloy single powder, or mixed powder of pure aluminum and aluminum alloy. Although the method for producing the base powder is not particularly limited, it is preferable to use powder having a particle size of 100 to 500 μm for 70% or more. The composition of the aluminum alloy is not particularly limited. Preferably, it contains one or more of these, with the balance being aluminum and unavoidable impurities.

A sintered body is produced by sintering the powder in an inert or reducing atmosphere, for example at a temperature of about 600-670°C. The sintered body (base portion 20) preferably has a porosity of 20 to 90%. When the porosity is 20% or more, the pore volume increases, which is advantageous in water absorption such as water absorption capacity. When the porosity is 90% or less, the strength of the porous body increases and it is easy to use. The porosity is preferably 60% or less in order to secure mechanical strength suitable for machining and installation.

The hydrophilic polymer layer 5 may have a chemical structure containing a hydrophilicity-imparting group in its molecule. Examples of hydrophilicity-imparting groups include acid groups such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups; carboxybetaine; , sulfobetaine, betaine structure-containing group such as phosphobetaine; polyoxyalkylene group such as polyoxyethylene group, polyoxypropylene group, polyoxyalkylene group containing both oxyethylene group and oxypropylene group; hydroxyl group, amide a tertiary amino group, a quaternary ammonium salt, and the like.

In particular, the hydrophilic polymer layer 5 preferably contains a hydrophilicity-imparting group-containing polymerizable unsaturated compound. Specific examples of hydrophilicity-imparting group-containing polymerizable unsaturated compounds include (meth)acrylic acid or its alkali metal salts, amine salts and ammonium salts, itaconic acid or its alkali metal salts, amine salts and ammonium salts, vinyl Sulfonic acid, allylsulfonic acid, 2-sulfoethyl (meth)acrylate, 2-acrylamido-2-methylpropanesulfonic acid, 3-sulfopropyl (meth)acrylate, 4-styrenesulfonic acid Alkali metal salts and amine salts of these sulfonic acids and ammonium salts, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate, alkali metal salts, amine salts and ammonium salts of these phosphoric acids; methacryloyloxyethyl-N,N-dimethyl-N-(3-sulfopropyl)ammonium betaine, methacryloyloxyethyl-N,N-dimethylammonium-α-methylcarboxybetaine; polyethylene glycol (meth)acrylate, polypropylene glycol (meth) acrylates, methoxypolyethylene glycol (meth)acrylate; 2-hydroxyethyl (meth)acrylate, N-vinyl-2-pyrrolidone, acrylamide, N,N-dimethylacrylamide; N-hydroxyalkyl (meth)acrylamides such as hydroxyethylacrylamide; N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, N,N -diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, 2-(methacryloyloxy)ethyltrimethylammonium chloride, 2-(methacryloyloxy)ethyltrimethylammonium bromide, 2-(meth)acryloyloxyethyl -2′-(trimethylammonium)ethyl phosphate, 2-(methacryloyloxy)ethyltrimethylammoniumdimethylphosphate, vinyl alcohol and the like.

In particular, the hydrophilic polymer layer 5 preferably contains polyvinyl alcohol (PVA). Polyvinyl alcohol (PVA) has the suggested formula (--CH ₂ CH(OH)--) _n and has many OH groups in the molecule. Moreover, the hydrophilic polymer layer 5 preferably contains silanol. Silanol is represented by the chemical formula Si--OH and exists on the surface of silica. Silanol exhibits hydrophilicity because it has a hydroxyl group.

The hydrophilic polymer layer 5 is obtained by coating the base 20, which is a sintered body of aluminum or an aluminum alloy. For example, when PVA is contained, for example, a solution in which PVA is mixed with phosphoric acid, phytic acid, silica, phenolic resin, etc., or a solution containing silica as a main component is applied to the outer surface of the base 20, and Baking drying is preferably carried out at 200 to 220° C. for 10 minutes or more, preferably 30 minutes or more. Conventionally known coating means such as spraying and immersion can be used for coating. Although the thickness of the hydrophilic polymer layer 5 is not particularly limited, it is preferably 0.1 to 10 μm for PVA and 0.1 to 1.5 μm for silanol. The hydrophilic polymer layer 5 has the effect of increasing the hydrophilicity of the surface of aluminum or an aluminum alloy, and is resistant to deterioration even at high temperatures. and maintain water absorption. Note that both the PVA layer and the silanol may be coated.

The hydrophilic polymer layer 5 may cover at least part of the outer surface of the base 20 . “Coating the outer surface” generally refers to a state in which the hydrophilic polymer layer 5 is formed on the outer surface of the base 20 when viewed macroscopically, but when viewed microscopically, the outer surface of the base 20 is covered. At least part of the surface particles of the substrate present on the surface (preferably on the outer surface side) need only be coated with the hydrophilic polymer layer 5, and the openings of the pores will not be blocked. "At least the outer surface" means that the hydrophilic polymer layer 5 may not be present on the inner surface of the porous body. However, it is preferable that the hydrophilic polymer layer 5 also exist on at least part of the inner surface (pore surface) of the substrate 2, especially near the outer surface. Note that "at least part of the outer surface of the substrate is covered" means that the hydrophilic polymer layer 5 does not necessarily cover the entire outer surface.

The porous body 1 of the present invention may further have a boehmite layer 3 on the surface of the substrate 2 , and may adopt a configuration in which a hydrophilic polymer layer 5 is provided on the boehmite layer 3 . Boehmite is an aluminum hydrated oxide, and is formed by immersing a sintered body of aluminum or an aluminum alloy in water at 80 to 100° C., preferably 95° C. or higher for 1.5 hours or longer (boehmite treatment). Since the higher the purity of the water, the more effective the boehmite treatment is, it is preferable to use purified water or pure water obtained by a purification method such as an ion exchange membrane method. After completion of the immersion, it is preferable to heat and dry (for example, 100° C. for 60 minutes). The boehmite layer 3 itself is hydrophilic but degrades quickly at high temperatures. However, by coating the hydrophilic polymer layer 5 thereon, a stronger hydrophilic portion can be formed on the surface of the substrate 2, so that deterioration of hydrophilicity can be prevented. The boehmite layer 3 also preferably covers at least the outer surface of the substrate 2 .

Second Embodiment An enlarged schematic view of a cross-section of a second embodiment of the invention is shown in FIG. In this embodiment, the substrate 2 of base 20 comprises zeolite particles 6 . Although FIG. 3 shows the zeolite particles 6 attached to or exposed on the surface of the substrate 2 , the zeolite particles 6 may be present within the pores 4 or partially embedded in the substrate 2 . In some cases. In any case, the zeolite particles 6 are preferably dispersed uniformly. The zeolite particles 6 may or may not be present on the outer surface of the porous body (substrate).

Zeolite is a general term for crystalline aluminosilicates, and its general formula is represented by (M ₂ ^I , M ^II )O.Al _{2 O} 3.mSiO _{2.nH 2} O, where M ^I is monovalent. is a cation selected from Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , NH ₄ ⁺ , Me ₄ N ⁺ (TMA), Et4N ⁺ (TEA), PR4N ⁺ (TPA), etc., and M ^II is 2 It is a valent cation and is selected from Ca ²⁺ , Ba ²⁺ , Sr ²⁺ , Mg ²⁺ , Zn ²⁺ and the like. Zeolites include synthetic zeolites, artificial zeolites, and natural zeolites. Zeolites have excellent water absorption performance and are resistant to deterioration even when exposed to high temperatures.

In the present invention, the type of zeolite is not limited, and any type of zeolite may be used. The particle size of the zeolite particles is preferably 500 μm or less, more preferably 30 to 150 μm. The zeolite particles 6 are contained in the porous body 1 at a rate of 0.1 mass % or more. The content of the zeolite particles 6 is preferably 0.2 mass % or more, more preferably 0.2 to 6.0 mass % of the porous body 1 . When the content of the zeolite particles 6 is 0.2% by mass or more, the water absorption is further improved. The upper limit of the content of the zeolite particles 6 is preferably set to 6.0% by mass in order to secure suitable mechanical strength by machining, installation, or the like. The zeolite particles 6 can be applied by mixing a predetermined amount of the zeolite particles 6 with aluminum or aluminum alloy base powder and sintering the mixture, but this is not limiting and other methods may be used.

Aluminum or an aluminum alloy having the above porosity is inherently excellent in water absorption. However, long-term exposure to high temperatures reduces water absorption. However, since zeolite has excellent water adsorption performance and is resistant to deterioration even at high temperatures, by attaching or burying the zeolite particles 6 to the substrate 2, even after being exposed to high temperatures for a long period of time, the water absorption properties of the porous body can be improved. can be maintained. Also in this embodiment, the substrate 2 may have a boehmite layer 3 on its surface.

Third Embodiment FIG. 4 shows a schematic cross-sectional view of a third embodiment of the porous body of the present invention. This porous body 1 also has a base 2 made of a sintered body of aluminum or an aluminum alloy and a base 20 having pores 4 . This base 20 is as described in the first embodiment.
In a third embodiment, the porous body 1 has a silicate layer 8 covering at least the outer surface 7 of the substrate 2 . "Coating the outer surface" and "at least the outer surface" are as described in the first embodiment. Preferably, the silicate layer 8 is also present on at least part of the inner surface of the substrate 2, especially near the outer surface.

The silicate layer 8 is obtained by applying a silicate treatment to a sintered body of aluminum or an aluminum alloy. A generally known treatment may be used as the silicate treatment. For example, the sintered body is immersed in a silicate treatment liquid having a silicate concentration of 0.3 to 5.0% by mass, a pH of 10.0 to 12.0, and a water temperature of 60 to 90° C. for 5 minutes or longer. The silicate layer 8 preferably has a thickness of, for example, 0.1-0.8 μm. The silicate layer 8 is a silicic film of aluminum, contributes to the action of increasing the hydrophilicity of the substrate, and is resistant to deterioration even at high temperatures. can be maintained and water absorption can be maintained.

Also in this embodiment, the substrate 2 may have a boehmite layer 3 on its surface. A configuration in which the silicate layer 8 is provided on the boehmite layer can also be adopted. As an example of processing for providing the boehmite layer 3 and the silicate layer 8, the sintered body is immersed in pure water at 95° C. or higher for about 2 hours (boehmite treatment), and then immersed in a silicic acid bath at 60 to 85° C. for 15 minutes. (Silicate treatment).

Other Embodiments Although the first to third embodiments have been described above, these embodiments may be combined, in which case, due to a synergistic effect, hydrophilicity after long-term exposure to high temperature, The effect of maintaining water absorption is further improved. In either case, the boehmite layer 3 can be formed by subjecting the surface of the substrate 2 to boehmite treatment in advance.
(1) The porous body 1 has a substrate 2 made of a sintered body of aluminum or an aluminum alloy, which has zeolite particles 6 , and a hydrophilic polymer layer 5 on at least the outer surface of a base portion 20 having the substrate 2 .
(2) The porous body 1 has a substrate 2 made of a sintered body of aluminum or an aluminum alloy, which has zeolite particles 6, and further has a silicate layer 8 on at least the outer surface of a base portion 20 having the substrate 2 thereon.
(3) The porous body 1 has a substrate 2 made of a sintered body of aluminum or an aluminum alloy, which has zeolite particles 6, and further has a silicate layer 8 on at least the outer surface of a base portion 20 having the substrate 2, and further It has a hydrophilic polymer layer 5 thereon.
(4) The porous body 1 has a silicate layer 8 on at least the outer surface of a base 20 having a base 2 made of a sintered body of aluminum or an aluminum alloy, and further has a hydrophilic polymer layer 5 thereon (Fig. 5).
The details of the hydrophilic polymer layer 5, the zeolite particles 6 and the silicate layer 8 are as described above.

As described above, the specific example of the embodiment of the present invention has been described with respect to the sintered body of aluminum or aluminum alloy. However, it is obvious to those skilled in the art that the present invention can be applied not only to aluminum or aluminum alloys but also to other materials (eg, metals such as stainless steel, copper, titanium, etc., ceramics, etc.). Furthermore, the porous body of the present invention is not limited to a sintered body, and may be other porous bodies such as foam metal.

The porous body according to the present invention is suitable for preventing dew condensation inside an environmental tester. However, the porous body according to the present invention is not limited to this application, and can be applied to equipment involving temperature rise/decrease in high-temperature environments. Examples include electronic devices used outdoors, such as smartphones, tablets, laptops, and earphones, and switchboards and electronic devices with high-temperature parts, such as compressors, lenses in projectors, printers, and floor heating systems.

Examples 1 to 22, 31 to 58 and Comparative Examples 61 to 63 of the porous bodies of the present invention were produced in the following manner. Aluminum alloy powders having compositions shown in Tables 1 to 4 were produced by an atomizing method. As for the particle size of this powder, 70% of the particles had a particle size of 200 to 450 μm.

In Examples 1 to 11, this aluminum alloy powder was mixed with zeolite powder (Zeolam (R) A-3 manufactured by Tosoh Corporation) at the ratio shown in Table 1 with a V-type mixer, and the mixed powder was converted to graphite without pressure. It was spread on a tray and sintered at 650° C. for 7 hours in a hydrogen atmosphere gas. The spray amount of the mixed powder was adjusted so that the thickness after sintering would be 3 mm. On the other hand, Comparative Examples 61 to 63 were sintered under the same conditions as above without adding zeolite powder. Table 1 shows the porosity of these samples.

Further, in Examples 12 to 20, the aluminum alloys having the compositions shown in Table 2 were sintered in the same procedure and under the same conditions as above without adding zeolite powder. The sintered body was subjected to boehmite treatment and silicate treatment. The boehmite treatment was performed by immersing the sintered body in pure water at 95° C. for 2 hours and then drying it for 60 minutes over 100 hours. After that, as a silicate treatment, the sintered body was immersed in a silicic acid bath in which sodium silicate was dissolved in water to a concentration of 0.5% by mass, heated to 80° C., and adjusted to pH 11.5 (treatment times are shown in Table 2). After immersion, it was washed with water and dried for 60 minutes in 100 hours.

In Example 21, only the silicate treatment was performed under the above conditions for 2.5 minutes without the boehmite treatment. In Example 22, the sample of Example 6 (0.08% by mass of zeolite was added) was subjected to the above boehmite treatment, and then subjected to silicate treatment under the above conditions for 15.0 minutes. Table 2 shows the porosity of these samples.

In Examples 31 to 42, the aluminum alloy sintered bodies produced without adding zeolite powder according to the above procedures and conditions were subjected to boehmite treatment in Examples 31 to 35 and 37 to 41, and in Examples 36 and 42, boehmite was applied. The hydrophilic polymer layer was coated without any treatment. The hydrophilic polymer layer is a hydrophilic Si-based film in Examples 31-36, and a film containing polyvinyl alcohol (PVA) in Examples 37-42. The composition of the Si-based film is mainly composed of SiO ₂ Si—OH (that is, contains silanol). A solution having the composition was applied to the outer surface of the aluminum sintered body by dipping (so-called dripping). After that, baking drying was performed for 20 minutes at 100° C. or more and 200° C. or less. Table 3 shows the hydrophilic polymer layer coating thickness and porosity of these samples.

In Examples 43-58, aluminum alloy sintered bodies produced without adding zeolite powder according to the above procedures and conditions were subjected to boehmite treatment in Examples 43-46 and 51-54, and in Examples 47-50 and 55. to 58 were not subjected to boehmite treatment, Examples 43, 44, 47, 48, 51, 52, 55 and 56 were subjected to silicate treatment; coated the hydrophilic polymer layer without silicate treatment. The hydrophilic polymer layer is a hydrophilic Si-based film in Examples 43-50, and a film containing polyvinyl alcohol (PVA) in Examples 51-58. The composition and coating method of these hydrophilic polymer layer coatings are the same as in Examples 31-42. Table 4 shows the hydrophilic polymer layer coating thickness and porosity of these samples.

In Comparative Examples 61 to 63, the aluminum alloy sintered bodies produced without adding zeolite powder according to the above procedure and conditions were not subjected to any of boehmite treatment, silicate treatment, and hydrophilic polymer layer coating.

For Examples 1 to 22, 31 to 58 and Comparative Examples 61 to 63 described above, an evaluation test was conducted on water absorbency after heating at a high temperature. In the evaluation test, heat treatment was performed at 180° C. in the air for 250 hours, 500 hours, 1000 hours, and 2000 hours (up to 3000 hours for Examples 1 to 22), and the samples were air-cooled to room temperature. made. A water droplet of 0.5 ml was dropped on the surface of each sample, and the time until the water droplet disappeared was measured. Tables 1 and 2 show the results. In the table, ○ indicates that the water droplets disappeared in 1 second or less, △ indicates that the water droplets disappeared in more than 1 second and within 5 seconds, and × indicates that it took longer than 5 seconds for the water droplets to disappear. .

From the results in Tables 1 to 4, Comparative Examples 61 to 63, which did not contain zeolite and were not treated with silicate, deteriorated in water absorption after heating for 250 hours. On the other hand, the examples according to the present invention all had good water absorbency even after heating for 3000 hours or 2000 hours.
Although a silicate solution was used for the silicate treatment in the above examples, it was also confirmed that other salts such as lithium salt can be similarly effective.

Claims (11)

A porous body having pores and a substrate, the substrate comprising Cu: 0.5 to 5.0% by mass, Si: 0.5 to 3.0% by mass, and Mn: 0.5 to 3.0% by mass made of an aluminum alloy containing one or more of the above, with the balance being aluminum and inevitable impurities,
The porous body comprises a hydrophilic element, the element comprises a hydrophilic polymer layer covering at least part of the outer surface of the substrate, and the hydrophilic polymer layer comprises polyvinyl alcohol (PVA) and silanol. A porous body containing Claim 1 , wherein said element further comprises 0.2 to 5.0 % by weight of zeolite in said porous body, said zeolite being in the form of zeolite particles, said zeolite particles being present at least on the pore surfaces of said substrate. The porous body described in . The element of claim 1 further comprising a 0.1-0.8 μm thick silicate layer covering at least a portion of the outer surface of said substrate, and having said hydrophilic polymer layer on said silicate layer. The porous body according to claim 1 or claim 2 . 4. The porous body according to any one of claims 1 to 3 , further comprising a boehmite layer covering at least part of the outer surface of the substrate in direct contact therewith. The porous body according to any one of claims 1 to 4 , wherein the porous body has a porosity of 20% to 90%. A method for manufacturing a porous body,
Cu: 0.5 to 5.0% by mass, Si: 0.5 to 3.0% by mass, Mn: 0.5 to 3.0% by mass, with the balance being aluminum and unavoidable impurities providing an aluminum alloy powder consisting of
preparing a zeolite powder with a mass of 0.2-5.0 % of the mass of the aluminum alloy powder;
mixing the aluminum alloy powder and the zeolite powder;
sintering the mixed powder into a porous body having a porosity of 20% to 90%;
coating at least part of the outer surface of the porous body with a hydrophilic polymer layer containing polyvinyl alcohol (PVA) and silanol;
A method for producing a porous body, comprising: 7. The method for producing a porous body according to claim 6 , further comprising the step of subjecting the porous body to a silicate treatment before the step of coating with the hydrophilic polymer layer . A method for manufacturing a porous body,
Cu: 0.5 to 5.0% by mass, Si: 0.5 to 3.0% by mass, Mn: 0.5 to 3.0% by mass, with the balance being aluminum and unavoidable impurities providing an aluminum alloy powder consisting of
sintering the aluminum alloy powder into a porous body having a porosity of 20% to 90%;
and a step of coating at least part of the outer surface of the porous body with a hydrophilic polymer layer containing polyvinyl alcohol (PVA) and silanol . 9. The method for producing a porous body according to claim 8 , further comprising the step of subjecting the porous body to a silicate treatment before coating with the hydrophilic polymer layer . 10. The method of any one of claims 6 to 9 , further comprising subjecting the porous body to a boehmite treatment after the step of sintering and before the step of treating the porous body with a silicate. a method for producing a porous body. The method for producing a porous body according to any one of claims 6 to 10 , wherein 70% or more of the aluminum alloy powder has a particle diameter of 100 to 500 µm.

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