JP2010189574A - Method for producing aqueous dispersion liquid crosslink-curable resin composition, aqueous dispersion liquid crosslink-curable resin composition, method for producing porous material, and porous material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aqueous dispersion liquid crosslink-curable resin composition which is a material formable of a porous thin film layer having fine pores, to provide an aqueous dispersion liquid crosslink-curable resin composition, to provide a method for producing a porous material, and to provide the porous material. <P>SOLUTION: In the method for producing an aqueous dispersion liquid crosslink-curable resin composition, obtained by adding water in an amount of ≥10 mass% to a liquid crosslink-curable resin composition, 0.1-5 mass% of hydrophilic fine particles having an average particle diameter of ≤1 μm is added to the liquid crosslink-curable resin composition and the resulting mixture is stirred. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a water-dispersed liquid cross-linked curable resin composition for forming fine pores using hydrophilic fine particles, a water-dispersed liquid cross-linked curable resin composition, a method for producing a porous material, and a porous material It is about.

  In recent years, with the progress of miniaturization and high-density mounting of precision electronic devices and communication devices such as medical fields, the diameters of electric wires and cables used for these devices have been further reduced. Furthermore, in signal lines and the like, the tendency to further increase the speed of transmission signals is remarkable, and the speed of transmission signals can be increased by reducing the dielectric constant as much as possible and making the insulator layer of the wires used for this thin. It is desired to plan.

  Conventionally, an insulating material having a low dielectric constant, such as polyethylene or fluorine resin, is used as the insulator. For forming the foamed insulator layer, a method of winding a film previously foamed on a conductor and an extrusion method are known, and the extrusion method is particularly widely used.

  Methods for forming foaming can be broadly divided into physical foaming methods and chemical foaming methods.

  As a physical foaming method, a volatile foaming liquid such as liquid chlorofluorocarbon is injected into the molten resin and foamed by its vaporization pressure, or bubbles are formed directly in the molten resin in the extruder such as nitrogen gas or carbon dioxide gas. For example, there is a method of generating fine cellular closed cells uniformly distributed in a resin by press-fitting a working gas (Patent Document 1).

  As a chemical foaming method, a foaming agent is dispersed and mixed in a resin, and after that, heat is applied to cause a decomposition reaction of the foaming agent, and foaming is performed using a gas generated by the decomposition. It is well known (Patent Document 2).

JP 2003-26846 A JP 11-176262 A

  By the way, in the method of injecting the volatile foaming liquid into the molten resin, the vaporization pressure is strong, and fine formation of bubbles is difficult, and there is a limit to thin-wall molding. Moreover, since the injection | pouring speed | velocity | rate of the volatile foaming liquid is slow, there also exists a problem that high-speed manufacture is difficult and productivity is inferior. Furthermore, the method of directly injecting the gas for forming bubbles in the extruder is limited in the formation of small-diameter and thin-walled extrusion, and requires special equipment and technology for safety, resulting in poor productivity and manufacturing costs. There is a problem that will lead to an increase.

  On the other hand, in the chemical foaming method, the foaming agent is kneaded in advance in the resin, dispersed and mixed, and after the molding process, the foaming agent is reacted with heat to cause foaming by the generated gas. There is a problem that it must be kept below the decomposition temperature of the agent. Furthermore, when the diameter of the wire becomes thin, there is another problem that the extrusion coating tends to cause disconnection due to the resin pressure, and it is difficult to increase the speed.

  In addition, physical foaming using chlorofluorocarbon, butane, carbon dioxide gas and the like has a problem of a large environmental load, and a foaming agent used for chemical foaming has a problem of high cost.

  The present invention has been obtained as a result of various studies in order to solve the above-mentioned problems, and the object thereof is a material that can easily form a porous thin film layer having fine pores that is environmentally friendly. The present invention provides a method for producing a certain water-dispersed liquid cross-linked curable resin composition, a water-dispersed liquid cross-linked curable resin composition, a method for producing a porous material, and a porous material.

  In order to achieve the above object, the invention according to claim 1 is a method for producing a water-dispersed liquid cross-linked curable resin composition comprising 10% by mass or more of water added to a liquid cross-linked curable resin composition. In this method, 0.1 to 5 mass% of hydrophilic fine particles having an average particle size of 1 μm or less are added to the mold resin composition, followed by stirring treatment.

  The invention according to claim 2 is the method for producing an aqueous dispersion liquid cross-linked curable resin composition according to claim 1, wherein the hydrophilic fine particles are fine particles obtained by synthesizing hydrophilic monomers such as acrylamide, methyl methacrylate, ethyl acrylate and the like. is there.

  The invention of claim 3 is an aqueous dispersion liquid cross-linked curable resin composition produced by the production method of claim 1 or 2.

  The invention of claim 4 is a porous material formed by removing water by heating after crosslinking and curing the water-dispersed liquid cross-linked resin composition obtained from claim 1 or 2.

  The invention of claim 5 is a method for producing a porous material, characterized in that it is formed by crosslinking and curing the water-dispersed liquid cross-linked curable resin composition obtained from claim 1 or 2, and then removing water by heating. is there.

  Invention of Claim 6 is a manufacturing method of the porous material of Claim 5 which uses a microwave heating for a heating.

  The invention according to claim 7 is a porous material produced by the method according to any one of claims 4 to 6.

  According to the present invention, water can be finely dispersed by combining hydrophilic fine particles with a liquid cross-linking curable resin composition to which water is added, and the cured product can be easily finely dehydrated by heating. It exhibits an excellent effect that a porous material having various pores can be obtained.

It is a cross-sectional view of the porous membrane-coated electric wire of the present invention. It is a cross-sectional view of a multilayer coated cable using the porous membrane-coated electric wire of the present invention. It is a cross-sectional view of a coaxial cable using the porous membrane-coated electric wire of the present invention. It is the microscope picture which expanded the 200-micrometer-thick film cross section produced by Example 1 of this invention 200 times. It is the microscope picture which expanded the film cross section of 200 micrometers in thickness produced by Example 2 of this invention 1000 times. It is the microscope picture which expanded the film cross section of 200 micrometers in thickness produced by Example 3 of this invention 1000 time. It is the microscope picture which expanded the hole part of the 200-micrometer-thick film cross section produced by Example 1 of this invention 5000 times. 2 is a photomicrograph of a cross section of a 200 μm thick film produced in Comparative Example 1 magnified 100 times. 4 is a photomicrograph at 100 times magnification of a 200 μm thick film cross section produced by Comparative Example 3. FIG. It is the figure which compared the dehydration efficiency by microwave heating and 120 degreeC oven heating.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

First, a porous membrane-coated electric wire, a multilayer coated cable, and a coaxial cable to which the water-containing water-absorbing polymer-containing resin composition of the present invention is applied will be described with reference to FIGS. 1 to 3. FIG. FIG. 3 is a plan view, and a porous membrane-covered electric wire 10 is formed by covering an insulating coating layer 1 made of a water-absorbing polymer-containing resin composition having fine pores 2 on the outer periphery of a plurality of conductors 3.

  FIG. 2 is a cross-sectional view of a multilayer coated cable using the porous membrane-covered electric wire 10 shown in FIG. 1, in which a skin layer or a coating layer 4 is formed on the outer periphery of the porous membrane-coated electric wire 10. 11 is formed.

  FIG. 3 is a cross-sectional view of a coaxial cable using the porous membrane-covered electric wire 10 shown in FIG. 1. The conductor 3 of the porous membrane-coated electric wire 10 is used as an inner conductor, and the outer periphery of the porous membrane-coated electric wire 10 is A coaxial cable 12 is formed by forming a shield wire or shield layer 5 and further forming a coating layer 6 on the outer periphery thereof.

In the present invention, the water-dispersed liquid cross-linked curable resin composition used as the insulating coating layer is
10 mass% or more of water is added to the liquid cross-linkable curable resin composition, and 0.1 to 5 mass% of hydrophilic fine particles having an average particle diameter of 1 μm or less are added to the liquid crosslinkable curable resin composition and stirred. Thus, a water-dispersed liquid cross-linked curable resin composition is obtained.

  After this water-dispersed liquid cross-linked curable resin composition is cross-linked and cured, the porous material can be produced by removing water by heating.

  For heating, microwave heating is preferably used.

  The liquid cross-linking curable resin composition is hardened by ultraviolet rays, heat, electron beam, visible light, etc., and is not particularly limited, but preferably a resin composition that is cross-linked and cured by ultraviolet rays, heat, or combined use. More preferably, an ultraviolet crosslinking curable resin composition is preferable.

  As the resin composition, known resin compositions such as ethylene-based, urethane-based, silicone-based, fluorine-based, epoxy-based, polyester-based, and polycarbonate-based resins can be selected, but the dielectric constant of the resin composition is 4 or less, preferably 3 or less. Things are good.

  The addition of 10 mass% or more of water to the liquid cross-linkable curable resin composition is less than 10 mass%, and it is difficult to obtain a low dielectric constant effect. Because it is small. Preferably 20-40 mass% is good. This is because if it exceeds 40 mass%, it becomes extremely difficult to form a stable porous film, and it becomes easy to make a large dispersion size of water.

  The hydrophilic fine particle is a particle having a high affinity with water and is not particularly limited as long as it can easily coordinate water around the particle. For example, synthetic fine particles using hydrophilic monomers such as acrylamide, methyl methacrylate, ethyl acrylate and the like can be mentioned.

  The reason why the hydrophilic fine particles are used is that the water added to the liquid cross-linkable curable resin composition can be finely dispersed in the liquid crosslinkable curable resin and the amount of water added can be increased. . The reason why the average particle size is 1 μm or less is that when the average particle size is larger than 1 μm, the dispersion size of water increases and the effect of increasing the amount of water added decreases.

  The reason why the addition amount of the hydrophilic fine particles is 0.1 to 5 mass% is that when the amount is less than 0.1 mass%, it is difficult to obtain the fine dispersion effect of water. This is because if it exceeds 5 mass%, the fine dispersion efficiency of water relative to the added amount is low, and the mechanical properties of the cured product are liable to be lowered. Moreover, water can be finely dispersed in the resin more efficiently by previously dispersing hydrophilic fine particles in water and adding them to the liquid cross-linking curable resin composition.

  The reason for dehydration by heating after crosslinking and curing is that, in addition to preventing a decrease in porosity due to volume shrinkage due to dehydration, it is possible to prevent changes in film thickness and outer diameter and obtain a stable product. In addition, since the coating can be formed in advance with pores, there is no need to foam, and there is no deterioration in adhesion between the conductor and the foam layer, which is likely to occur in gas foaming with conventional gas injection and foaming agents, and stable. Is obtained.

  For the liquid cross-linking curable resin composition, a dispersant, a leveling agent, a coupling agent, a colorant, a flame retardant, an antioxidant, an electrical insulation improver, a filler, and the like are added as necessary. be able to.

  The reason why microwave heating is used to heat and dehydrate water in a water-dispersed liquid cross-linked curable resin composition is that water is rapidly heated by microwaves and affects water-absorbing polymers and surrounding resins. This is because heat dehydration can be carried out in a short time and vacancies can be efficiently formed.

  Further, by using a waveguide type microwave heating furnace, heat dehydration can be performed continuously. Furthermore, you may use in combination with a normal heating furnace.

  FIG. 10 shows the relationship between the heating time and the dehydration rate when water in the insulating coating layer of the wire is heated and dehydrated by microwave heating and 120 ° C. oven heating.

  From FIG. 10, it can be seen that microwave heating can be efficiently dehydrated in an extremely short time compared to ordinary electric furnace and oven heating.

  Although the insulating coating layer of the insulated wire has been described above, the porous material (foamed material) obtained from the water-dispersed liquid cross-linked curable resin composition using the hydrophilic fine particles of the present invention is a buffer material, an impact absorbing film ( Sheet), light reflectors, and the like.

  Moreover, since it is a liquid cross-linking curable resin composition, a porous layer can be formed on the surface of the irregular shape.

  Examples of the present invention and comparative examples will be described below.

  The resin composition A shown in Table 1 was used as the liquid cross-linked resin composition (base resin composition).

Resin composition A;
A film having a thickness of approximately 200μm were prepared by curing by ultraviolet irradiation dose 500 mJ / cm ² under a nitrogen atmosphere using a 15MIL blade, the dielectric constant determined by a cavity resonance method (@ 10 GHz) was 2.65 .

Hydrophilic fine particles A;
Add 200 g of ethanol to a 300 ml three-necked flask, add 0.65 g of methacrylic acid, 11.8 g of acrylamide, 0.65 g of methylenebisacrylamide, and 0.75 g of 2,2′-azobis (isobutyronitrile), and add nitrogen. After stirring and dissolving at room temperature while bubbling, the temperature was raised to 60 ± 2 ° C. while stirring, and after performing a polymerization reaction for 2 hours, ethanol was dried and removed to obtain hydrophilic fine particles A having an average particle diameter of 0.6 μm. Obtained.

Hydrophilic fine particles B;
Add 200 g of ethanol to a 300 ml three-necked flask, add 0.65 g of methacrylic acid, 11.8 g of acrylamide, 0.65 g of methylenebisacrylamide, and 0.25 g of 2,2′-azobis (isobutyronitrile), and add nitrogen. After stirring and dissolving at room temperature while bubbling, the temperature was raised to 60 ± 2 ° C. while stirring, and after performing a polymerization reaction for 4 hours, ethanol was dried and removed to obtain hydrophilic fine particles B having an average particle size of 15 μm. .

  In Examples 1 to 4 and Comparative Examples 1 to 4, the addition amount of hydrophilic fine particles and water (distilled water) was changed to 100 parts by weight of the base resin composition, respectively, and then stirred at a rotation speed of 500 rpm for 1 hour. This is a water-dispersed liquid cross-linked curable resin composition (resin composition).

  Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 2.

  Evaluation of Examples and Comparative Examples in Table 2 was performed as follows.

<Film formability>
The resin composition is formed on a glass plate using a 7 MIL, 15 MIL blade to form a coating film having a width of 100 mm and a length of 200 mm, and an ultraviolet irradiation amount of 500 mJ / cm ² using an ultraviolet irradiation conveyor device in a nitrogen atmosphere. The film was irradiated and cured, and it was confirmed whether or not smooth film formation with a film thickness of about 100 μm or 200 μm was possible.

<Porosity>
The porosity was determined by the following formula.

Porosity (%) = [1- (Sample weight after dehydration / Sample volume after dehydration) / (Weight of resin sample without water / Volume of resin sample without water)] × 100
<Dielectric constant>
A film sample was formed into a strip shape having a width of 2 mm and a length of 100 mm, and three dielectric constants were measured at a frequency of 10 GHz by a cavity resonance method, and an average value thereof was obtained.

<Hole diameter>
It calculated | required from the size of the void | hole observed from the cross-sectional photograph of five places which image | photographed (500 times) the cross section of the film and the electric wire coating layer with the electron microscope.

<Example 1>
After adding 0.5 parts by weight of hydrophilic fine particles A and 15 parts by weight of water to 100 parts by weight of the resin composition A, the mixture is stirred for 1 hour at a rotation speed of 500 rpm and is a water-dispersed liquid cross-linked curable resin composition (resin composition 1). Got.

  It was confirmed that the resin composition had good film moldability.

  After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. It was confirmed that the porosity determined from the film volume and weight after complete dehydration was 11.8% and 12.3%, respectively, close to the water content. The dielectric constant of the 200 μm film measured by the cavity resonance method was 2.39 (@ 10 GHz). Furthermore, when the hole diameter was investigated about the hole observed from the cross-sectional photograph (refer FIG. 4) of five places using an electron microscope in a 200 micrometer film, it was 3-12 micrometers. Further, when the inside of the pores was magnified (see FIG. 7), many hydrophilic fine particles 7 were confirmed on the pore wall surfaces and were not observed in the resin layer, so the hydrophilic fine particles efficiently finely dispersed water. It was confirmed.

<Example 2>
After adding 1 part by weight of hydrophilic fine particles A and 30 parts by weight of water to 100 parts by weight of the resin composition A, the mixture is stirred for 1 hour at a rotation speed of 500 rpm to obtain a water-dispersed liquid cross-linked curable resin composition 2 (resin composition 2). Obtained.

  The resin composition 2 was confirmed to have good film moldability.

  After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. It was confirmed that the porosity determined from the film volume and weight after complete dehydration was 21% and 21.4%, respectively, close to the water content.

  The dielectric constant of the 200 μm film measured by the cavity resonance method was 2.2 (@ 10 GHz).

  Furthermore, when the hole diameter was investigated about the hole observed from the cross-sectional photograph (refer FIG. 5) of five places using an electron microscope in a 200 micrometer film, it was 3-15 micrometers.

  Further, when the inside of the pores was enlarged and observed, many hydrophilic fine particles were confirmed on the pore wall surfaces as in Example 1, and were not observed in the resin layer, so that the hydrophilic fine particles efficiently finely dispersed water. It was confirmed.

<Example 3>
After adding 3 parts by weight of hydrophilic fine particles A and 30 parts by weight of water to 100 parts by weight of the resin composition A, the mixture is stirred for 1 hour at a rotation speed of 500 rpm to obtain a water-dispersed liquid cross-linked curable resin composition 3 (resin composition 3). Obtained.

  It was confirmed that the resin composition 3 had good film moldability. After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. It was confirmed that the porosity determined from the film volume and weight after complete dehydration was 21.1% and 21.8%, respectively, which were close to the water content. The dielectric constant of the 200 μm film measured by the cavity resonance method was 2.19 (@ 10 GHz). Furthermore, when the hole diameter was investigated about the hole observed from the cross-sectional photograph (refer FIG. 6) of five places using an electron microscope in a 200 micrometer film, it is 3-12 micrometers, and the hole diameter is smaller than Example 2. Was confirmed. Further, when the inside of the pores was enlarged and observed, many hydrophilic fine particles were confirmed on the pore wall surfaces as in Example 1, and were not observed in the resin layer, so that the hydrophilic fine particles efficiently finely dispersed water. It was confirmed.

<Example 4>
After adding 5 parts by weight of hydrophilic fine particles A and 60 parts by weight of water to 100 parts by weight of the resin composition A, the mixture is stirred for 1 hour at a rotation speed of 500 rpm to obtain a water-dispersed liquid cross-linked curable resin composition 4 (resin composition 4). Obtained.

  It was confirmed that the resin composition 4 had good film moldability. After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. It was confirmed that the porosity determined from the film volume and weight after complete dehydration was 33.4% and 34.5%, respectively, which almost coincided with the water content. The dielectric constant of the 200 μm film measured by the cavity resonance method was 1.96 (@ 10 GHz). Furthermore, when the hole diameter was investigated about the hole observed from the cross-sectional photograph of five places using an electron microscope in a 200 micrometer film, it was 3-40 micrometers. In addition, when the inside of the pores was enlarged and observed, many hydrophilic fine particles were confirmed on the pore wall surface as in the example and were not observed in the resin layer, so that the hydrophilic fine particles efficiently finely dispersed water. It was confirmed.

<Comparative Example 1>
An aqueous dispersion liquid crosslinkable curable resin composition 5 (resin composition 5) without using the hydrophilic fine particles of Example 1 was obtained.

  The resin composition 5 was confirmed to have good film moldability. After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. It was confirmed that the porosity determined from the film volume and weight after complete dehydration was 10.1% and 11.2%, respectively, almost equal to the water content. The dielectric constant of the 200 μm film measured by the cavity resonance method was 2.42 (@ 10 GHz). Furthermore, when the pore diameters of the pores observed from five cross-sectional photographs using an electron microscope (see FIG. 8) were examined in a 200 μm film, the pore diameter was 5 to 150 μm, which was much larger than that of the example, and water was dispersed. It was confirmed that it was not.

<Comparative example 2>
A water-dispersed liquid cross-linked curable resin composition 6 (resin composition 6) in which the amount of water added in Comparative Example 1 was 30 parts by weight was obtained.

  When an attempt was made to produce a film with respect to the resin composition 6, water and resin were easily separated, and no film could be formed.

<Comparative Example 3>
An aqueous dispersion liquid cross-linked curable resin composition 7 (resin composition 7) was obtained in which the amount of hydrophilic fine particles added in Example 1 was 0.1 parts by weight.

  It was confirmed that the resin composition 7 had good film moldability. After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), as a result of observing the cross section with an electron microscope, it was confirmed that a large number of holes were formed. The porosity determined from the film volume and weight after complete dehydration was 10.7% and 11.8%, respectively. The dielectric constant of the 200 μm film measured by the cavity resonance method was 2.4 (@ 10 GHz). Furthermore, when the hole diameter was investigated about the hole observed from the cross-sectional photograph (refer FIG. 9) of five places using an electron microscope in a 200 micrometer film, it was confirmed that it is 5-100 micrometers and is almost the same as the comparative example 1. FIG.

<Comparative example 4>
After adding 5 parts by weight of hydrophilic fine particles B having a particle size of 15 μm and 60 parts by weight of water to 100 parts by weight of the resin composition A, the mixture is stirred for 1 hour at a rotation speed of 500 rpm, and the water-dispersed liquid cross-linked curable resin composition 8 (resin composition 8) was obtained.

  When the film was produced about the resin composition 8, the unevenness | corrugation produced on the surface and it confirmed that a moldability was inferior. After heating this for 5 minutes using a microwave heating device (oscillation frequency 2.45 GHz), the cross section was observed with an electron microscope. As a result, formation of vacancies was confirmed, but an electron microscope was used on a 200 μm film. The hole diameter of the holes observed from the five cross-sectional photographs was 5 to 100 μm, and the variation was larger than that of Example 4.

  As described above, as described in Examples and Comparative Examples, water can be finely dispersed in the liquid cross-linkable curable resin composition by using hydrophilic fine particles A having a particle diameter of 1 μm or less from Examples 1, 2, 3, and 4. And fine pores can be formed. On the other hand, in Comparative Example 1 in which no hydrophilic fine particles were used, a film having a large pore diameter was easily formed, and in Comparative Example 2 in which the amount of water was increased, a film could not be formed at all. Further, in Comparative Example 3 in which the amount of hydrophilic fine particles A added is small, there is no fine dispersion effect of water. Therefore, the amount of hydrophilic fine particles A added is preferably 0.1 mass% or more. In Comparative Example 4 in which hydrophilic fine particles B having a large particle size (15 μm) were added, the film moldability was poor and the variation in pore diameter was large. Therefore, the particle size of the hydrophilic fine particles A should be as small as possible, and preferably 0.1 μm or less.

DESCRIPTION OF SYMBOLS 1 Insulation coating layer 2 Hole 3 Conductor 4 Skin layer or coating layer 5 Shield wire or shielding layer 6 Coating layer 7 Hydrophilic fine particles

Claims (7)

  In the method for producing a water-dispersed liquid cross-linked curable resin composition obtained by adding 10 mass% or more of water to the liquid cross-linked curable resin composition, the liquid cross-linked curable resin composition has a hydrophilic property with an average particle size of 1 μm or less. A method for producing a water-dispersed liquid cross-linked curable resin composition, comprising adding 0.1 to 5 mass% of fine particles and stirring.   The method for producing an aqueous dispersion liquid cross-linked curable resin composition according to claim 1, wherein the hydrophilic fine particles are fine particles obtained by synthesizing hydrophilic monomers such as acrylamide, methyl methacrylate, ethyl acrylate and the like.   A water-dispersed liquid cross-linked curable resin composition produced by the production method according to claim 1 or 2.   A porous material formed by crosslinking and curing the water-dispersed liquid cross-linked curable resin composition obtained from claim 1 or 2 and then removing water by heating.   A method for producing a porous material, wherein the water-dispersed liquid cross-linked curable resin composition obtained from claim 1 or 2 is cross-linked and cured, and then water is removed by heating.   The method for producing a porous material according to claim 5, wherein microwave heating is used for heating.   A porous material produced by the method according to claim 4.

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