JP2005313091A - Method for manufacturing filter medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter medium high in voids and excellent in filtering efficiency, and a method for manufacturing the same. <P>SOLUTION: The method for manufacturing a filter medium comprises the steps of forming an emulsion-structural-body having a predetermined shape by using an emulsion 32 containing a fiber 11 (synthetic fibers) and a resin for bonding (made of synthetic resins) and including bubbles (included by stirring, foaming or the like) and drying the body to remove water contained in the emulsion to obtain the filter medium of the predetermined shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a filter medium in which fibers are bonded with a bonding resin, the porosity is high, and the filtration efficiency is excellent.

  Conventionally, a filter medium in which fibers are dispersed in a porous resin body (for example, see Patent Documents 1 and 2), and a filter medium in which bubbles are included in the web (for example, Patent Document 3). Etc.) are known. The filter medium described in Patent Document 1 uses a foamable resin having a communicating hole such as urethane foam as a fiber binder, and since the binder does not become a resistance, the filter medium has a low pressure loss and is stable over the long term. be able to. In addition, the filter medium described in Patent Document 2 includes fibers that are irregularly mixed in a foamable resin having communication holes such as foamed urethane, has good life performance, and has a degree of freedom in shape. Therefore, it is possible to obtain a filter medium with less filtration efficiency. Furthermore, the filter medium described in Patent Document 3 has voids formed by foamable particles on a web made using an aqueous dispersion composed of ultrafine fibers, skeletal fibers, and foamable particles, resulting in low pressure loss, high It can be set as a filter medium provided with filtration efficiency, high intensity, etc.

JP 2001-129328 A 2001-190913 Japanese Patent Laid-Open No. 9-155127

However, in the filter medium described in Patent Documents 1 and 2, it is necessary that the porous resin body having a communication hole as a binder reduces clogging of the filter medium and reduces pressure loss while forming voids between fibers. In addition, it is not easy to obtain a filter medium having a sufficient gap as a whole. Moreover, in the filter medium described in Patent Document 3, it is necessary to uniformly form sufficient voids in the web with the foamable particles, and further improvement is desired.
The present invention solves the above-mentioned problems of the prior art, and a filter medium in which fibers are sufficiently bonded by a bonding resin, a porosity is high, and a filter medium excellent in filtration efficiency is manufactured by a simple operation and process. It aims at providing the manufacturing method of.

The present invention is as follows.
1. Water contained in the bubble-containing emulsion is formed by forming an emulsion structure having a predetermined shape using a bubble-containing emulsion containing fibers and a bonding resin and having bubbles therein, and then drying the emulsion structure. And producing a filter medium having a predetermined shape.
2. 1. The fiber as described above, wherein the fiber is a resin fiber, and the resin forming the resin fiber and the bonding resin are the same type of resin. The manufacturing method of the filter medium as described in 1 ..
3. The bubble-containing emulsion is obtained by foaming an emulsion containing the fiber and the bonding resin. Or 2. The manufacturing method of the filter medium as described in 1 ..
4). 2. The viscosity of the emulsion at 25 ° C. is 0.3 to 10 Pa · sec. The manufacturing method of the filter medium as described in 1 ..
5. 2. The emulsion described above further contains at least one of a surfactant and a pyrolytic foaming agent. Or 4. The manufacturing method of the filter medium as described in 1 ..
6). 2. The ratio (Vp / Ve) between the volume (Vp) of the bubble-containing emulsion and the volume (Ve) of the emulsion before foaming is 1.5 to 10. To 5. The manufacturing method of the filter medium of any one of these.
7. The ratio (Vf / Vp) of the volume (Vf) of the filter medium and the volume (Vp) of the bubble-containing emulsion is 1 to 10. To 6. The manufacturing method of the filter medium of any one of these.
8). The above-mentioned 1. performing the drying in a state where the bubble-containing emulsion and the mold surface of the mold are brought into contact with each other. To 7. The manufacturing method of the filter medium of any one of these.
9. The drying is performed in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other, and then foamed. To 7. The manufacturing method of the filter medium of any one of these.
10. 1. foaming simultaneously with the drying in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other; To 7. The manufacturing method of the filter medium of any one of these.

According to the method for producing a filter medium of the present invention, it is possible to easily produce a filter medium having a strong and lightweight resin-bonded portion and excellent in filtration efficiency with a simple operation and apparatus.
Further, when the fibers are resin fibers and the resin forming the resin fibers and the bonding resin are the same type of resin, the fibers can be reliably bonded with the bonding resin.
Furthermore, when a bubble-containing emulsion is prepared by foaming an emulsion containing fibers and a bonding resin, it is possible to obtain a bubble-containing emulsion in which sufficient bubbles are contained without using a foaming agent, and the filtration efficiency is improved. An excellent filter medium can be obtained.
Moreover, when the viscosity of the emulsion at 25 ° C. is 0.3 to 10 Pa · second, the bubble-containing emulsion can be easily prepared.
Furthermore, when the emulsion further contains at least one of a surfactant and a pyrolytic foaming agent, a filter medium having a higher porosity and excellent filtration efficiency can be obtained.
In addition, when the ratio (Vp / Ve) of the volume (Vp) of the bubble-containing emulsion to the volume (Ve) of the emulsion before foaming is 1.5 to 10, the strength of the resin joint portion is high and It can be a lightweight filter medium.
Further, when the ratio (Vp / Vf) of the volume (Vp) of the bubble-containing emulsion to the volume (Vf) of the filter medium is 1 to 10, the bonding strength at the entanglement point of each fiber is increased, and the filtration efficiency It can be set as the filter medium which is excellent in.
In addition, when drying is performed in a state where the bubble-containing emulsion is brought into contact with the mold surface of the mold, the obtained filter medium can be used as it is, and no post-processing is required, which is advantageous in terms of cost. is there.
Furthermore, drying is performed in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other, and then foaming is performed, and foaming is performed simultaneously with the drying in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other. In this case, the obtained filter medium has a higher porosity, excellent filtration efficiency, and can be directly used as a product, and does not require post-processing, which is advantageous in terms of cost.

Hereinafter, the filter medium manufactured by the method of the present invention and the method for manufacturing the filter medium of the present invention will be described in detail.
[1] Filter medium As shown in FIG. 1, the filter medium includes fibers (for example, 11, 11, and 11) and resin joint portions (for example, 12) that join the entanglement points of the respective fibers. This filter medium 1 has a three-dimensional structure in which voids are formed between the respective fibers and between the fibers and the resin bonding portion, and these voids serve as flow paths and function as a filter medium.
The “fibers” are not particularly limited as long as the fibers are bonded by resin bonding portions, voids are formed between the respective fibers and between the fibers and the resin bonding portions, and function as a filter medium. Examples of the fibers include resin fibers, glass fibers, ceramic fibers such as silicon carbide fibers, and metal fibers such as stainless steel fibers. These fibers may be used alone or in combination of two or more.

  The fiber is preferably a resin fiber that is easy to bond at the resin bonding portion, is moderately flexible, can be easily post-processed, and can be used as a filter medium having sufficient strength. Examples of the resin fibers include fibers made of synthetic fibers, natural fibers, and recycled fibers. Synthetic fibers include polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyamide fibers, polyester fibers, acrylic fibers, and vinylon fibers. Natural fibers include hemp such as cotton, flax and cannabis, cellulose, jute, wool and silk. Furthermore, examples of regenerated fibers include rayon and acetate. Moreover, the fiber which consists of biodegradable resin, such as polylactic acid, polyglycolic acid, and polyethylene succinate, can also be used. It is preferable to use a fiber made of this biodegradable resin because the disposal of the filter medium after use becomes easy. These resin fibers may be used alone or in combination of two or more.

  The fiber may be a short fiber or a fiber obtained by cutting a long fiber into a predetermined length. Further, it may be a fiber obtained by cutting a monofilament (single fiber) to a predetermined length or a fiber obtained by cutting a multifilament (bundling fiber) to a predetermined length. Furthermore, a composite fiber may be used, and examples of the composite fiber include a core-sheath fiber and a fiber in which fibers of different materials in the warp direction are joined. The core-sheath fiber is formed by a core made of a thermoplastic resin having a high melting point and a sheath made of a thermoplastic resin that covers the core and has a low melting point, for example, a core made of a high melting point polyester fiber; And a sheath formed of a low-melting-point polyester fiber. The diameter and length of the fibers for forming the filter medium are not particularly limited. When the fibers are short fibers, when the long fibers are cut into a predetermined length, and when the monofilament is cut into a predetermined length In any case, it is preferable that the diameter is 1 to 50 μm, particularly 10 to 30 μm, and the length is 0.1 to 5.0 mm, particularly 0.5 to 2.0 mm. When the multifilament is cut into a predetermined length, the monofilament constituting the multifilament has a wire diameter of 1 to 50 μm, particularly 10 to 30 μm, and a length of 0.1 to 5.0 mm, particularly 0.5. It is preferable that it is -2.0mm and a number is 18-144, especially 36-72. The monofilaments constituting the multifilament may be the same material or may be two or more different materials.

  The “resin joint portion” is a portion that joins the entanglement points of the respective fibers. The resin used for forming the joint is not particularly limited. Examples of this resin include polyamide resins, polyester resins, acrylic resins, vinyl acetate resins, ethylene copolymer resins such as ethylene-acrylate copolymers and ethylene-vinyl acetate copolymers, polyurethane resins, epoxy resins, and phenol resins. Can be mentioned. Furthermore, biodegradable resins such as polylactic acid, polyglycolic acid and polyethylene succinate can also be used. It is preferable to use a fiber made of this biodegradable resin because the disposal of the filter medium after use becomes easy. The resin bonding portion may be composed of only one of these resins or may be composed of two or more. In addition, although the fiber is covered with the resin at the entanglement point, the resin may adhere to other parts of the surface of the fiber, particularly the fiber surface of the peripheral part of the joint part, unless the filtration efficiency is greatly reduced. .

  When the fiber is a resin fiber, the resin fiber and the resin bonding portion are preferably formed of the same kind of resin. If the resin fiber and the resin bonding portion are formed of the same kind of resin, the fibers can be more reliably bonded at the resin bonding portion. The resin of the same kind is a monomer unit in which 10% by mass or more, particularly 50% by mass or more (including 100% by mass) of the monomer units of each resin are composed of the same monomer. Means that. Moreover, in order to make many fibers join reliably and to make a homogeneous filter medium, it is more preferable that the resin fiber and the resin joined body are each made of one kind of resin, and they are the same kind of resin.

[2] Method for Producing Filter Medium A filter medium having a predetermined shape can be formed by drying a bubble-containing emulsion containing fibers and a bonding resin and removing bubbles, and removing water.
The above-mentioned description in the case of a filter medium can be applied to the “fiber” as it is. Further, the “bonding resin” is not particularly limited, but an ethylene copolymer resin such as a polyamide resin, a polyester resin, an acrylic resin, a vinyl acetate resin, an ethylene-acrylate copolymer and an ethylene-vinyl acetate copolymer, polyurethane Resin, epoxy resin, phenol resin, etc. are mentioned. Furthermore, biodegradable resins such as polylactic acid, polyglycolic acid and polyethylene succinate can also be used. It is preferable to use a fiber made of this biodegradable resin because the disposal of the filter medium after use becomes easy. These bonding resins may be used alone or in combination of two or more.

  In the case where resin fibers are used as the fibers, the resin forming the resin fibers and the bonding resin are preferably the same type of resin. If the resin forming the fiber and the bonding resin are the same type of resin, the fibers can be reliably bonded to each other by the bonding resin. In addition, the meaning of this kind of resin is as above-mentioned. In addition, in order to reliably join the entangling points of many fibers and to make a homogeneous filter medium excellent in filtration efficiency, one type of resin is used as each of the resinous fibers and the bonding resin, and the same type of resin is used. More preferably, it is used.

The “bubble-internal emulsion” can be prepared by foaming an emulsion containing fibers and a bonding resin.
The bonding resin contained in the “emulsion” can be 10 to 70% by mass when the total of the bonding resin and the medium water is 100% by mass, 20 to 60% by mass, In particular, the content is preferably 30 to 50% by mass. When the content of the bonding resin is 30 to 50% by mass, the particles made of the bonding resin are uniformly dispersed in water, and a homogeneous filter medium can be obtained. Furthermore, the fiber can be 10 to 90% by mass, preferably 20 to 80% by mass, and particularly preferably 30 to 70% by mass, when the total of the fiber and the bonding resin is 100% by mass. . If the fiber content is 30 to 70% by mass, the fibers can be reliably bonded by the bonding resin, the filter medium having a high porosity and sufficient strength can be obtained.
The emulsion may be a dispersion in which bonding resin particles are suspended in water, and may be a dispersion obtained by polymerizing the bonding resin by emulsion polymerization, suspension polymerization, or the like. It may be a dispersion liquid suspended in water using the like. Moreover, the dispersion liquid which suspended the precursor resin (uncured epoxy resin etc.) before hardening in water using an emulsifier etc. may be sufficient.

  The method of foaming the emulsion is not particularly limited, and examples thereof include a method of stirring the emulsion, introducing air, dispersing and foaming, and a method of blowing gas into the emulsion and foaming. As this gas, air, nitrogen gas or the like can be used. Moreover, it can also be made to foam by stirring while blowing gas into the emulsion. The temperature of the emulsion at the time of foaming is not particularly limited and can be in the range of 5 ° C to room temperature (15 to 25 ° C, particularly 22 to 25 ° C). This temperature may be room temperature, and heating is not particularly required, but it may be heated to 40 to 60 ° C. for the purpose of adjusting the viscosity.

In order to sufficiently foam and make a bulky bubble-containing emulsion, the emulsion has a viscosity at 25 ° C. of 0.3 to 10 Pa · sec, particularly 0.3 to 5 Pa · sec, more preferably 0.3 to 2 Pa · sec. Preferably there is. If this viscosity is 0.3 to 2 Pa · sec, the emulsion can be easily foamed by any method such as foaming by stirring and blowing a gas to foam. A bulky bubble-internal emulsion can be obtained.
This viscosity is a value measured using a B-type viscometer under the conditions of rotor number 4 and rotor rotation speed 60 rpm.

  By foaming the emulsion, it becomes bulky, the contained fibers are dispersed and arranged in random directions, and voids are formed between the fibers. The volume ratio of the bubble-containing emulsion to the emulsion before foaming is not particularly limited, but the ratio of the bubble-containing emulsion volume (Vp) to the emulsion volume (Ve) (Vp / Ve) is 1.5 to 10. It is preferably 1.5 to 5, more preferably 1.5 to 3. If (Vp / Ve) is 1.5 to 3, the fibers can be arranged in random directions, and sufficient voids can be formed between the fibers. Thereby, it is possible to obtain a filter medium having a high porosity, excellent filtration efficiency, and easy post-processing. This ratio (Vp / Ve) can be easily confirmed by attaching a volume scale to the container used when foaming the emulsion.

  The emulsion preferably contains the “surfactant” having an effect of stabilizing bubbles. As this surfactant, an anionic surfactant such as a carboxylate, a sulfonate, and a phosphate ester salt, and a cationic surfactant such as an aliphatic quaternary ammonium salt can be used. As the surfactant, a carboxylate having an excellent effect of stabilizing bubbles and the like is preferable. Examples of the carboxylate include ammonium salts, sodium salts, potassium salts and the like of higher fatty acids such as palmitic acid, stearic acid, and oleic acid. Is mentioned. Furthermore, in order to obtain a bulky bubble-internal emulsion and a filter medium having a higher porosity, it is preferable to use a surfactant that is excellent not only in stabilizing the bubbles but also in promoting foaming. As such a surfactant, ammonium palmitate, ammonium stearate, ammonium oleate and the like are often used, and ammonium stearate is particularly preferable.

  Although the compounding quantity of surfactant is not specifically limited, When an emulsion is 100 mass%, it can be set to 0.1-20 mass%, 0.5-10 mass%, especially 0.5-5 mass. % Is preferable. If the compounding amount of the surfactant is 0.5 to 5% by mass, the bubbles can be sufficiently stabilized, and a bulky bubble-containing emulsion can be obtained. By using this bulky bubble-containing emulsion, a filter medium having a high porosity and an excellent filtration efficiency can be obtained.

  The emulsion can further contain other additives. Although the additive varies depending on the type of resin and the like, a required amount of additives such as a foaming agent, an antioxidant, an antistatic agent, a lubricant, a plasticizer, and a pigment can be blended. In particular, a foaming agent other than water can be blended in order to obtain a bubble-internal emulsion in which more bubbles are contained by heating during drying described later, and a filter medium having a higher porosity. Examples of the foaming agent include a pyrolytic foaming agent, a volatile foaming agent, and a hollow particle foaming agent. These foaming agents may use only 1 type and may use 2 or more types. As this thermal decomposition type foaming agent, inorganic thermal decomposition type foaming agents such as sodium bicarbonate, ammonium carbonate and ammonium bicarbonate can be used. In addition, organic pyrolytic foaming agents such as azodicarbonamide, azobisisobutyronitrile, and dinitrosopentamethylenetetramine can also be used. Furthermore, as the volatile foaming agent, aliphatic hydrocarbons such as propane and butane, halogenated hydrocarbons such as chlorodifluoromethane and difluoromethane, carbon dioxide and nitrogen can be used. Although the compounding quantity of a foaming agent is not specifically limited, When a resin for joining is 100 mass parts, it can be set as 1-50 mass parts, and can be 1-30 mass parts, especially 2-25 mass parts. preferable.

A filter medium having a predetermined shape is formed by drying the bubble-containing emulsion and removing the contained water.
The drying is not particularly limited as long as water can be removed, and an apparatus used for drying, a drying temperature, a drying time, and the like are not particularly limited. For example, it can be dried in a temperature range of 40 to 100 ° C., particularly 60 to 80 ° C. using a thermostatic bath or the like. Moreover, it can also be made to dry in a shorter time by making the inside of a tank pressure reduction. When the inside of the tank is depressurized, the drying temperature can be lowered, and it can be sufficiently dried even at room temperature (20 to 35 ° C.). Thus, when dried under relatively mild conditions, the bubble-containing emulsion does not increase any more, or the volume increase is small, and a filter medium approximating the shape and size of the bubble-containing emulsion is formed.

  On the other hand, the volume of the filter medium becomes larger when the temperature is rapidly raised to 80 to 130 ° C., particularly 100 to 130 ° C., by foaming by electron beam irradiation or the like. In particular, when a surfactant excellent in foaming action such as ammonium stearate is blended in the emulsion, the volume of the filter medium becomes larger. This large volume filter medium has a high porosity and improves filtration efficiency. On the other hand, when it expands or foams excessively, strength falls. Therefore, it is preferable to set an expansion rate or a foaming rate in accordance with the purpose and application.

  Furthermore, a filter medium having a larger volume can also be obtained when the above pyrolytic foaming agent is blended in the emulsion. When the pyrolytic foaming agent is blended, it is not necessary to raise the temperature to a particularly high temperature as in the case where water is used as the foaming agent, and heating may be performed at a temperature at which the pyrolytic foaming agent decomposes. In this case, it is dried at a temperature range of 40 to 100 ° C., particularly 60 to 80 ° C., and in the case of a foaming agent having a decomposition temperature of less than 100 ° C., it can be foamed simultaneously with drying. In the case of a foaming agent having a decomposition temperature exceeding 100 ° C., after drying, the foaming agent can be further heated to a temperature at which the foaming agent decomposes to be foamed. Further, the temperature can be raised from the beginning to a temperature at which the pyrolytic foaming agent decomposes, and foaming can be performed simultaneously with drying. In addition, it is preferable to adjust the temperature to foam by each thermal decomposition type foaming agent.

  The ratio (Vf / Vp) of the volume (Vf) of the filter medium and the volume (Vp) of the bubble-containing emulsion is preferably 1 to 10, more preferably 1 to 8, and particularly preferably 1 to 5. When (Vf / Vp) is 1 to 5, a filter medium having a sufficient porosity, high filtration efficiency, and high strength can be obtained. This ratio (Vf / Vp) is preferably 2 to 10, particularly 2 to 5 from the viewpoints of porosity and filtration efficiency, and 1 to 4, particularly 1 to 2 from the viewpoint of strength and the like. It is preferable. (Vf / Vp) can be confirmed by an actual product when the filter medium has a simple shape, and when the filter medium has a complicated shape, the same bubble-containing emulsion is a volume-scaled container. And dried under the same conditions, and the volume ratio at this time can be (Vf / Vp).

  In the case of the filter medium obtained by drying under relatively mild conditions as described above, (Vf / Vp) is often 1 to 4, and preferably 1 to 2. This filter medium has high filtration efficiency and high strength. On the other hand, in the case of a filter medium obtained by rapidly raising the temperature as described above and mixing water with a foaming agent and a foaming agent and foaming, (Vf / Vp) is 2 to 10 In particular, it is preferably 2 to 5. This filter medium has a higher porosity and excellent filtration efficiency. There are open bubbles and open cells, but open cells are preferable.

  The method of drying the bubble-containing emulsion to form a filter medium having a predetermined shape is not particularly limited, but the bubble-containing emulsion and the mold surface of the mold are dried to remove water to remove the filter medium having the predetermined shape. can do. With such a method, even if the filter medium has a particularly complicated shape, the obtained filter medium can be used as a product as it is in a specific application, and post-processing such as cutting, grinding, and bending is not necessarily required. The mold is not particularly limited, and has a mold surface such as a convex shape or a concave shape with a predetermined shape, and is used by attaching a bubble-containing emulsion to the mold surface (see FIGS. 3 to 5), and an upper mold and a lower mold. A cavity having a predetermined shape between the mold and a foam-filled emulsion used in the cavity (see FIG. 6) can be used.

Specific examples of the method for producing a filter medium using this mold include the following methods.
(1) A mold having a predetermined shape such as a convex shape and / or a concave shape is immersed in the bubble-containing emulsion, the bubble-containing emulsion is adhered to the surface of the mold, then dried, and then released. The product is a specific shape (see Example 1). In the case of the molds as shown in FIGS. 3 to 5, after the bubble-containing emulsion was adhered, another mold having a mold surface of the same shape was pressed against the mold surface to form between both mold surfaces. It is preferable to form the filter medium in a state in which the bubble-containing emulsion is filled in a space having a predetermined thickness. Further, when the angle formed by the adjacent convex portions is as large as 60 °, particularly 90 ° or more, it is not always necessary to use another mold.
(2) Applying the bubble-containing emulsion to the mold surface of a mold having a predetermined shape such as a convex shape or a concave shape, attaching the bubble-containing emulsion to the mold surface, then drying, and then releasing the mold. With a specific shape product.
(3) A bubble-containing emulsion is filled in a cavity having a predetermined shape of a mold, then dried, and then demolded to obtain a product having a specific shape.
(4) A mold having a mold surface having a predetermined shape such as a convex shape and / or a concave shape is immersed in the bubble-containing emulsion, and the bubble-containing emulsion is adhered to the mold surface, or a predetermined shape such as a convex shape and / or a concave shape. Applying the bubble-containing emulsion to the mold surface of the mold having the mold surface, attaching the bubble-containing emulsion to the mold surface, then drying, then foaming, and then releasing the mold, To do.
(5) A mold having a mold surface having a predetermined shape such as a convex shape and / or a concave shape is immersed in the bubble-containing emulsion, and the bubble-containing emulsion is adhered to the mold surface, or a mold having a predetermined shape such as a convex shape or a concave shape. A foam-containing emulsion is applied to the mold surface of a mold having a surface, the bubble-containing emulsion is adhered to the mold surface, then foamed simultaneously with drying, and then released to obtain a product of a specific shape.
(6) Filling the cavity with the bubble-shaped emulsion into the predetermined shape of the mold, followed by drying, then foaming, and then demolding, or filling the cavity with the bubble-shaped emulsion in the predetermined shape of the mold Then, it is foamed simultaneously with drying, and then demolded to obtain a product with a specific shape.
With these methods, even if the filter medium has a particularly complicated shape, the obtained filter medium can be used as a product as it is in a specific application, and post-processing such as cutting, grinding, and bending is not necessarily required.

  As a method for forming the filter medium, it is possible to dry the bubble-containing emulsion to obtain a filter medium that does not have a specific product shape, and cut, grind, or bend the filter medium into a specific shape to obtain a product. This method requires a post-process and may be low in efficiency, but can be made into a filter medium having a complicated shape by cutting, grinding, or bending. Furthermore, it is made of resin, and a foam-containing emulsion is put into a space portion of a member having a specific shape space, for example, a cylindrical member, and dried to obtain a product in which the member and the filter medium are integrated. You can also. The filter medium is often used in a form supported by a reinforcing material or the like, but a product in which this member and the filtering medium are integrated can be used without being supported by the reinforcing material or the like.

Hereinafter, the present invention will be described in detail with reference to FIGS.
Example 1
As shown in FIG. 2, 50 mass% polylactic acid is dispersed and contained in a glass container 21 having a volume of 5 liters equipped with a stirring blade 211 (the number average molecular weight of polylactic acid is 130,000). 1 liter of polylactic acid fiber 11 dispersed in this emulsion and containing the same amount of polylactic acid (monofilament cut into the required length, with an average diameter of 20 μm and an average length of 1 mm. 3), the stirring blade was rotated at a high speed of 500 rpm, stirred for 10 minutes, and air was mixed into the emulsion to prepare a bubble-containing emulsion 32 as shown in FIG. The viscosity of the emulsion measured by the above method was 0.5 Pa · sec. The volume of the bubble-containing emulsion read from the volume scale provided on the inner wall of the container was 2 liters, and Vp / Ve calculated from this volume (Vp) and the volume of the added emulsion (Ve) was 2. It was.

  Thereafter, as shown in FIG. 3, a stainless steel mold 4 having a plurality of convex portions 41 [the height of the mountain-shaped convex portions (a in FIG. 3) is 30 mm, and the length in the length direction of the convex portions. (The direction perpendicular to the paper surface, that is, the length of the mold) is 70 mm. ] Was immersed in the bubble-containing emulsion 32 for 5 seconds. Next, as shown in FIG. 4, the mold is taken out from the bubble-containing emulsion, and the mold having the bubble-containing emulsion 32 attached to the convex portion 41 is left in a thermostatic chamber adjusted to 60 ° C. for 5 hours, Was removed to form a filter medium. Thereafter, as shown in FIG. 5, the formed filter medium was peeled from the mold 4 to obtain a filter medium 101 having a bellows structure. In addition, the thickness of the coating film which consists of a bubble inherent emulsion was 5 mm, and the thickness of the filter medium which cooled to room temperature after drying was 5 mm. Since there was no change in the area, the ratio of the volume (Vf) of the filter medium to the volume (Vp) of the coating film composed of the bubble-containing emulsion can be calculated from these thicknesses, and Vf / Vp was 1. . Thus, Vf and Vp are approximate, and in Example 1, the structure of the bubble-containing emulsion is almost the same as the structure of the filter medium. Thus, a complicated shaped filter medium could be obtained without requiring post-processing.

Example 2
As shown in FIG. 6, a cavity is formed between the upper mold 51 and the lower mold 52 to obtain a filter medium having a bellows structure [the height of the mountain-shaped convex portion is 30 mm, and the length in the length direction of the convex portion. (The direction perpendicular to the paper surface, that is, the length of the mold) is 70 mm, and the distance between the upper mold surface and the lower mold surface is 5 mm. ] Was filled with the bubble-containing emulsion 32 prepared in Example 1, and this mold was left in a thermostatic chamber adjusted to 60 ° C. for 5 hours to remove water and form a filter medium. Although not shown, this mold is provided with a thin tube for drawing water out of the mold. Thereafter, the mold was removed to obtain a filter medium 102 having a bellows structure. The volume of the bubble-containing emulsion filled in the cavity was 1260 ml, and the thickness of the filter medium cooled to room temperature after drying was 5 mm. The ratio Vf / Vp between the volume (Vf) of the filter medium calculated from the thickness and area and the volume (Vp) of the filled bubble-containing emulsion was about 1. Thus, Vf and Vp are approximate, and also in Example 2, it was possible to obtain a filter medium having a complicated shape approximate to the shape of the cavity without requiring post-processing.

Example 3
As shown in FIG. 7, 0.1 liter of the bubble-containing emulsion 32 prepared in Example 1 was put into a glass container 22 having a volume of 0.5 liter, and this was put into a microwave oven and irradiated with an electron beam. The bubble-containing emulsion was rapidly heated and water was removed and foamed. As a result, the bubble-containing emulsion foamed as shown in FIG. 8, and the filter medium 103 was formed. The ratio (Vf / Vp) of the volume (Vf) of the filter medium to the volume (Vp) of the bubble-containing emulsion was about 4. Thus, the bubble-containing emulsion was expanded, and a filter medium with a higher porosity was obtained. This filter medium 103 can be made into a product of a required shape by post-processing such as cutting, grinding, and bending. In Example 3, drying and foaming were performed at the same time. However, after drying, foaming can also be performed by further raising the temperature. In Example 3, a cup-shaped container is used. However, if a cylindrical container is used, the entire inside of the cylinder is filled with the filter medium, and an air flow channel tube having a filtering function can be easily obtained. Can get to.

FIG. 3 is an explanatory diagram schematically showing an enlarged part of the filter medium of Example 1. It is a schematic diagram which shows a mode that emulsion is thrown into a container, a fiber is mix | blended and stirred and air is mixed. It is a schematic diagram which shows a mode that the convex-shaped part of a shaping | molding die is immersed in the bubble internal emulsion with which the fiber was mix | blended after stirring. It is a schematic diagram which shows the mode after drying the bubble inherent emulsion adhering to the shaping | molding die picked out from the container, and removing water. It is a schematic diagram which shows a mode that the filter medium was demolded from the shaping | molding die. It is a schematic diagram which shows the filter medium formed in the cavity of a shaping | molding die. It is a schematic diagram which shows a mode that the small amount of prepared bubble emulsion was moved to another container. It is a schematic diagram which shows a mode that the bubble internal emulsion was foamed by irradiating an electron beam, and the filter medium with a high porosity was obtained.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Filter medium, 11; Fiber, 12: Resin joint part, 21 and 22; Container, 211; Stirrer blade, 31; Emulsion, 32; Emulsion in bubble, 4; Convex mold, 41; 101, 102; bellows structure filter medium, 103; high porosity filter medium formed by foaming a bubble-containing emulsion.

Claims (10)

  Forming an emulsion structure of a predetermined shape using a bubble-containing emulsion containing fibers and a bonding resin and containing bubbles, and then drying the emulsion structure to provide water contained in the bubble-containing emulsion And producing a filter medium having a predetermined shape.   The method for producing a filter medium according to claim 1, wherein the fiber is a resin fiber, and the resin forming the resin fiber and the bonding resin are the same kind of resin.   The method for producing a filter medium according to claim 1 or 2, wherein the bubble-containing emulsion is obtained by foaming an emulsion containing the fiber and the bonding resin.   The method for producing a filter medium according to claim 3, wherein the emulsion has a viscosity at 25 ° C of 0.3 to 10 Pa · sec.   The method for producing a filter medium according to claim 3 or 4, wherein the emulsion further contains at least one of a surfactant and a pyrolytic foaming agent.   6. The ratio (Vp / Ve) between the volume of the bubble-containing emulsion (Vp) and the volume of the emulsion before foaming (Ve) is 1.5 to 10. 6. The manufacturing method of the filter medium as described in claim | item.   The ratio (Vf / Vp) of the volume (Vf) of the filter medium to the volume (Vp) of the bubble-containing emulsion is 1 to 10. The filter medium according to any one of claims 1 to 6, Production method.   The method for producing a filter medium according to any one of claims 1 to 7, wherein the drying is performed in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other.   The method for producing a filter medium according to any one of claims 1 to 7, wherein the drying is performed in a state where the bubble-containing emulsion and the mold surface of the mold are in contact with each other, and foaming is performed thereafter.   The method for producing a filter medium according to any one of claims 1 to 7, wherein foaming is performed simultaneously with the drying in a state where the bubble-containing emulsion and a mold surface of the mold are in contact with each other.

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