JP2007290012A - Manufacturing method of anisotropy porous material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an anisotropy porous material which can maintain initial functions such as alleviation of lowering in removal capacity of a filter for a fluid over long period of time. <P>SOLUTION: A mold 1 preliminarily disposed with two or more preform bodies 2 is filled with molten metal 3 by a process of a molten metal forging method, and is solidified to obtain a molded body. Thereafter, this molded body is fired to remove the preform bodies 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is an anisotropic porous material used for catalyst, impact energy absorption, sound absorption, liquid separation, contaminant removal in the field of transportation equipment, architecture, civil engineering, air conditioning equipment, medical equipment, chemicals, water treatment and other industrial equipment. The present invention relates to a method for producing a quality material.

  Porous materials having a large number of pores are used in a wide range of applications such as filters, sound absorbing materials, shock absorbing materials, and heat insulating materials for various fluids regardless of the gas phase or liquid phase (for example, non-patent documents). 1). As an example, a purification filter used for purification of a water treatment facility or the like will be described below.

  The purification filter is installed in a water treatment facility and removes various organic substances and microorganisms. However, there is a possibility that sulfide, chloride, or other harmful substances present in the atmosphere are dissolved in rainwater, and it is feared that the natural purification action by sand gravel and soil is not in time. This is a major social problem in the water cycle that continues today.

  River water collects and uses such rainwater, but in such a situation, tap water contains various harmful components and is used for chlorides added to sterilize microorganisms. There are trihalomethanes that are suspected to be carcinogenic.

  In addition to various organic wastewater, organic substances such as humic substances present in natural water react with free chlorine used in purification treatment, so that safe drinking water can be obtained. It is also necessary to remove these trace components and bacteria. Distillation and filtration are the main methods, but the filtration method using an activated carbon filter is widely used at present, and various shapes are commercially available.

  Selection criteria for activated carbon for water treatment used for activated carbon filters are defined by the Japan Water Works Association Standard (JWWA K113-1974). In the water treatment plant, wet carbon is mixed in a slurry state, but the choice of injection point and the mixing contact time are lengthened, so the restrictions on site and power are not so constant. Some removals of trihalomethane are not completely removed or cannot be removed depending on the type of activated carbon used.

  Chemical plants and food processing plants produce large amounts of wastewater containing metals and organic matter. Even if it is below a certain reference value, if a trace amount of harmful components is continued, the accumulated amount will increase, resulting in non-negligible pollution. For this reason, a high-quality purification member is continuously required for the waste liquid. After all, activated carbon is used for these main bodies, but there are many problems such as a large amount of cost due to the large amount used and frequent replacement required.

  Moreover, for the same reason as drinking water, there is a possibility that harmful components may flow into the environment without knowing the appropriate replacement time. Accordingly, there is a demand for a purification member that is more water-permeable, inexpensive, and excellent in adsorption capacity.

  Although there are trace amounts of impurities in chemically synthesized products or products extracted from natural substances and purified, activated carbon has been conventionally used in these purification processes. The reason for using activated carbon for purification is to separate impurities from a uniform solute, and utilizes the fact that the pores in the activated carbon adsorb the impurities. However, although the adsorption capacity of activated carbon is strong, the adsorption capacity is limited and a better method is required.

  In addition, decolorization is a very difficult process in the same purification process. Many dyes are one of the substances that are difficult to remove by various purification methods, and it can be seen that complete removal is difficult visually even if highly purified. In this decolorization process, activated carbon has been used in the past, but there is still a limit to the adsorption capacity, and a substance or method with a higher capacity has been sought. In particular, activated carbon has been conventionally used for decolorization and purification of highly viscous solutions, but there is a problem that highly viscous substances are difficult to pass through activated carbon. If the particle size is increased to facilitate passage, the adsorptive power decreases, and if the particle size is decreased and the adsorption capacity is increased, a highly viscous solution cannot be passed. It has been sought.

  At present, the water purifiers sold in Japan are mainly “activated carbon + hollow fiber membrane” type. This is a system that removes odorous substances and organic substances with activated carbon and removes germs and rust with a hollow fiber membrane. Antibacterial materials are coated with silver on the surface. In addition, a hollow fiber membrane (microfilter) is used. The hollow fiber membrane is made of plastic, and bundles fibers with a diameter of 0.4 mm that are hollow like macaroni, and the wall of the fiber has countless small holes of 0.1 to 0.01 microns. It is open and allows water to pass through the surface of the membrane by applying a hydrophilizing agent. The hydrophilizing agent is a synthetic surfactant (main ingredient of synthetic detergent).

  Recently, hollow fiber membrane filters have also been applied to condensate filtration devices for nuclear power plants and thermal power plants. Particularly in thermal power plants, in recent years, in order to improve energy efficiency and plant reliability, optimum management of condensate and feed water quality is required more than ever. Chemicals are injected into the water supply system of current thermal power plants to suppress system corrosion.

  The mainstream of the condensate purification equipment installed for removing impurities is a combined method of ion exchange resin-type desalting equipment and an electromagnetic filter that has been applied before the development of hollow fiber membrane filters. In recent years, in order to improve the reliability of the plant, a technique for suppressing the chemical injection amount is being applied. In this case, the ability of removing impurities by the electromagnetic filter is lowered.

  The hollow fiber membrane filter is a filter in which 10,000 cylindrical membrane filters having a macaroni cross section are bundled. A single hollow fiber membrane has a large number of fine through-holes having a pore diameter of about 0.1 μm. When water containing solid particles larger in diameter than the through-holes is treated with the hollow fiber membrane filter, the solid particles are removed from the pores. Without passing through, only water passes into the membrane and is filtered.

Further, in recent years, it is expected that demand will expand from the viewpoints of environmental measures and energy saving as a system for separating active ingredients from a mixture using a metal porous membrane and purifying water. Porous metal is a porous material consisting of high porosity (95% or more) and connected pores, and is made of foam metal having a three-dimensional network structure with various materials. Can be manufactured.
NEDO 2004 results report, “Development of high-efficiency biomass energy conversion technology / research and development of biomass ethanol concentration using zeolite membrane”

  In the above-described conventional purification filter, as described above, the “water activated carbon + hollow fiber membrane” type is the mainstream of the water purifier. This is a system that removes odorous substances and organic substances with activated carbon and removes germs and rust with a hollow fiber membrane.

  In addition, since germs grow inside the activated carbon after long-term use, the activated carbon is coated with silver to provide antibacterial properties. However, if the antibacterial activity is strong, the effects on the human body, such as silver poisoning, can be considered. Therefore, a hollow fiber membrane (microfilter) is used. A small hole provided in the hollow fiber membrane cuts germs and rust, but when mold is generated on the dead bodies of germs collected here, the taste of purified water changes.

  Furthermore, the plastic that is the raw material of the hollow fiber membrane is water repellent, and water cannot pass through an enormous surface area with ultrafine holes of 0.1 μm (per hundredth of 1 mm). Further, the shape is changed by backwashing when removing water pressure or microorganisms. Due to this shape change, the hole diameter changes, and it becomes impossible to remove germs, rust and the like that should have been removed.

  Moreover, the above-mentioned metal porous body is also a porous material made of connected pores and is a foam metal having a three-dimensional network structure. However, a shape change is caused by backwashing when removing water pressure or microorganisms. When this shape change occurs, the pore diameter changes, and it becomes impossible to remove germs, rust, and the like that should have been removed.

  The present invention has been made in view of the above, and it is intended to provide a method for producing an anisotropic porous material capable of maintaining an initial function over a long period of time, such as reducing a reduction in removal capability in a fluid filter. Objective.

  The method for producing an anisotropic porous material according to the present invention is a method for producing an anisotropic porous material comprising a plurality of pores, wherein the plurality of pores has an orientation. Filling a molten metal by a molten metal forging process into a mold in which a plurality of preform bodies having any form of fibers, wires, and rods are arranged in advance, and solidifying the molten metal filled in the mold And a step of removing the preform from the molded body.

  The method for producing an anisotropic porous material according to the present invention is a method for producing an anisotropic porous material comprising a plurality of holes, wherein the plurality of holes form an array having directionality. Including a step of obtaining a formed body by filling a molten metal by a molten forging process into a mold in which a plurality of preform bodies made of metal-like metal are previously arranged, and solidifying the molten metal filled in the mold. It is characterized by.

  According to the present invention, a mold in which a plurality of preform bodies are arranged in advance is filled with a molten metal by a process of molten metal forging, and a molded body is obtained by solidifying the metal filled in the mold. Therefore, the anisotropic porous material having a plurality of pores in which the pores form a directional array can be easily produced. The initial function can be maintained over a long period of time, such as reducing the reduction in removal capability in the filter.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a view for explaining a method for producing an anisotropic porous material according to an embodiment of the present invention.

  As shown in FIG. 1, a plurality of preform bodies 2 are arranged in advance in a mold 1 used in the method for producing an anisotropic porous material according to the present embodiment. For example, carbon fiber is used as the preform body 2. As shown in FIG. 1, the preform body 2 is arranged in the mold 1 with the directions aligned in one direction.

  Then, the molten metal 3 is filled into the mold 1 by a process of a molten metal forging method such as a gravity casting method, a low pressure casting method, or a die casting method, and then the molten metal 3 is solidified to obtain a formed body. The molten metal 3 filled in the mold 1 has as a main component one or more selected from aluminum, titanium, iron, copper, nickel, cobalt, and tin.

  Next, the obtained molded body is fired at a temperature not higher than the melting point of the molten metal, and the preform body 2 is burned and removed. For the firing, an electric furnace or a heating furnace whose temperature and atmosphere can be adjusted is used.

  Through the above steps, an anisotropic porous material having a large number of pores can be obtained. FIG. 2A is a plan view of the anisotropic porous material obtained by the method of the present invention, and FIG. 2B is a cross-sectional view taken along line AA ′ of FIG.

  As shown in FIGS. 2 (a) and 2 (b), the anisotropic porous material 5 obtained by the method of the present invention has a large number of holes 6, and these holes 6 are aligned in one direction. . Further, the size of the hole 6 is the same in the surface portion and the inside, and the passage of the hole 6 is linear.

  The diameter of the hole 6 is preferably 0.1 to 600 μm in terms of a sphere. If the diameter of the hole 6 is 0.1 to 600 μm, it can be produced by the method of the present invention. If the diameter is less than 0.1 μm, the production by the method of the present invention is difficult. When the diameter exceeds 600 μm, it is in a category that can be manufactured by existing machining such as drilling, and this is not included in the concept of the present invention.

  Moreover, it is preferable that the dispersion | variation in the diameter of the preform body 2 shown in FIG. 3 is 10% or less. FIG. 4 is a table showing the amount of permeated water of a water purification filter using the anisotropic porous material 5 produced by the method of the present invention when the variation of the diameter of the preform body 2 is 3, 6, 10, 15%. FIG. 5 is a graph showing the relationship between the diameter variation of the preform body 2 and the amount of permeated water.

  As shown in FIGS. 4 and 5, when the variation in the diameter of the preform body 2 increases, the variation in the permeated water amount also increases. Since this variation in the amount of permeate causes problems in purification, it is desirable that the variation in the amount of permeate is small. As shown in FIGS. 4 and 5, when the variation in the diameter of the preform body 2 is 10% or less in average diameter, the variation in the amount of permeated water is relatively small, so that this numerical value is supported.

  When the preform body 2 is set in the mold 1, it is necessary to align the direction of the preform body 2 in advance as described above. As shown in FIG. 6, when the cross section of the anisotropic porous material 10 obtained by the method of the present invention is observed as shown in FIG. Or the direction which forms the hole 12 inclined to some extent is desirable. Thereby, in the water purification filter using the anisotropic porous material obtained by the method of the present invention, an enormous amount of water can pass through the ultrafine holes.

  It is important that the inclination angle θ of the inclined holes 12 is not less than an angle that is not parallel to the surface of the anisotropic porous material 10. For example, in the hole 15 perpendicular to the flowing water direction, a stable permeated water amount cannot be maintained.

  In addition, as a preform body, in addition to the above-described fibers such as carbon fibers, powder, granular bodies, wires, rod-shaped bodies, hollow cylindrical metals, and the like can be used. Here, when a hollow cylindrical metal is used as the preform body, the step of removing the preform body after solidifying the molten metal to obtain a molded body is unnecessary. In this case, the hollow cylindrical preform body forms pores of the anisotropic porous material.

  As described above, according to the present embodiment, a molded body is obtained by filling and solidifying the molten metal 3 in the mold 1 in which a plurality of preform bodies 2 are arranged in advance by the process of the molten metal forging method. Since the preform body 2 is removed by firing at a temperature equal to or lower than the melting point of the molten metal, an anisotropic porous material having a plurality of pores in which the pores form an array having directionality can be easily produced. .

  And the water purification filter using the anisotropic porous material obtained has no water repellency like plastic, and since there is no deformation of the hole diameter with respect to the water pressure, it can pass a huge amount of water. . Further, it is possible to reduce the reduction in removal capability and maintain the initial function over a long period of time.

  As described above, the anisotropic porous material obtained by the method of the present embodiment is used as a material for a water purification filter, so that it is stable over a long period of time and enables efficient purification and purification at a low cost. It has an excellent feature.

  Moreover, by changing the pore diameter of the anisotropic porous material, a wide range of applications from a filter for water purification that captures microorganisms to a photothermal exchange material that stores solar heat is possible.

(Modification)
Next, the modification of embodiment of the manufacturing method of the anisotropic porous material which concerns on this invention is demonstrated.

In this modified example, as shown in FIG. 7, a resin coating 22 is applied to the surface of a preform body 21 made of powder, granules, fibers, wires, rods, etc. to a uniform thickness. FIG. 7A is a plan view of the preform body 21 to which the resin coating 22 is applied, and FIG. 7B is a cross-sectional view taken along line BB ′ of FIG.

  And the preform body 21 which gave the resin coating 22 is arrange | positioned to the metal mold | die 1 as shown in FIG. FIG. 8A is a diagram in which the preform body 21 to which the resin coating 22 is applied is arranged in the mold 1, and FIG. 8B is a cross-sectional view taken along the line CC ′ in FIG. As shown in FIGS. 8A and 8B, by applying the resin coating 22, the preform body 21 can be arranged in the mold 1 at regular intervals, and the pores of the anisotropic porous material obtained are obtained. Can be aligned at regular intervals.

  Then, the mold 1 is filled with the molten metal and the molded body obtained by solidifying the molten metal is fired, and the preform body 21 is burned and removed. Here, when an organic material is used as the material of the resin coating 22, the resin coating 22 can be removed by firing, and the fired residual material can be completely removed by washing after removal. Moreover, since the obtained anisotropic porous material is made of metal, it can be easily cleaned.

  In this modified example, the variation in the diameter of the preform body 21 is preferably 10% or less for the same reason as described above.

It is a figure for demonstrating the manufacturing method of the anisotropic porous material which concerns on embodiment of this invention. (A) is a top view of the anisotropic porous material obtained by the method of this invention, (b) is AA 'sectional drawing of (a). It is wire diameter sectional drawing of a preform body. It is a table | surface figure which shows the permeated water amount of the water purification filter using the anisotropic porous material manufactured by the method of this invention when the dispersion | variation in the diameter of a preform body is 3, 6, 10, 15%. It is a graph which shows the relationship between the dispersion | variation in the diameter of a preform body, and the amount of permeated water. It is a figure for demonstrating the formation direction of a hole. (A) is a top view of the preform body which gave resin coating, (b) is BB 'sectional drawing of (a). (A) is the figure which has arrange | positioned the preform body which gave resin coating to the metal mold | die, (b) is CC 'sectional drawing of (a).

Explanation of symbols

1 Mold 2, 21 Preform body 3 Molten metal 5 Anisotropic porous material 6 Hole 22 Resin coating

Claims (6)

A method for producing an anisotropic porous material containing a plurality of pores, wherein the plurality of pores form an array having directionality,
Molten metal filled with a molten metal by a molten metal forging process in a mold in which a plurality of preform bodies having any form of powder, granule, fiber, wire, and rod-shaped body are arranged in advance. Obtaining a molded body by solidifying
Removing the preform from the molded body. A method for producing an anisotropic porous material, comprising:   The method for producing an anisotropic porous material according to claim 1, wherein the step of removing the preform body is a step of firing the molded body.   The method for producing an anisotropic porous material according to claim 1, wherein a resin is coated on the surface of the preform body with a uniform thickness. A method for producing an anisotropic porous material containing a plurality of pores, wherein the plurality of pores form an array having directionality,
A step of obtaining a formed body by filling a molten metal by a molten metal forging process into a mold in which a plurality of preform bodies made of hollow cylindrical metal are previously arranged, and solidifying the molten metal filled in the mold. A method for producing an anisotropic porous material, comprising:   The molten metal with which the mold is filled has as a main component at least one selected from aluminum, titanium, iron, copper, nickel, cobalt, and tin, according to any one of claims 1 to 4. The manufacturing method of anisotropic porous material of description. The method for producing an anisotropic porous material according to any one of claims 1 to 5, wherein a variation in diameter of the plurality of preform bodies is 10% or less.

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