JP2009095787A - Agent and method for removing harmful substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly efficient agent for removing harmful substances with a low-pressure drop free from shortening its life by its compression. <P>SOLUTION: The agent for removing harmful substances constituted of a support consisting of first fibers having a diameter of smaller than 1 μm and second fibers having a diameter of not smaller than 1 μm is characterized in that the ratio of the first fibers and the second fibers changes in the direction of the thickness of the film of the support. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a harmful substance removing material made of fibers and a harmful substance removing method using the same.

  In recent years, infectious diseases caused by bacteria, molds, viruses, and the like have become a social problem. For example, there are concerns about mass infection in hospitals and places where a large number of unspecified people gather such as public facilities. In particular, infection in hospitals may cause the occurrence of MRSA (methicillin-resistant Staphylococcus aureus) and the like due to the abuse of antibiotics.

  In this regard, in recent buildings, ducts are provided in all rooms, and air is circulated through these ducts to adjust the room temperature etc. of the entire building, so that the inside of the facility floats through this air conditioner. Bacteria, molds, viruses, and the like often diffuse throughout the facility, and it has been considered that it is particularly effective to block infection routes using such air as a medium. In other words, bacteria, mold, viruses, or fine suspended matters in the air (dust, etc.) are adsorbed on fine filters as air media such as air conditioners and air purifiers, and titanium oxide or strong acidity. The sterilization zone is provided to inactivate and remove bacteria, molds, viruses, and the like that pass through the sterilization zone.

  Patent Document 1 describes a filter medium composed of a layer in which nanofibers and microfibers are mixed. However, there is no description about controlling the ratio of nanofibers and microfibers. Moreover, although the filter medium which controlled the ratio of the fine fiber is described in patent document 2, the fiber diameter of the fiber currently used is a thing of micrometer order.

JP 2004-17041 A JP 60-216818 A

  The layer composed of nano-sized fibers is compressed by the wind pressure and the pore diameter is reduced, resulting in an increase in pressure loss and a decrease in efficiency, resulting in a decrease in filter life. This invention made it the subject which should be solved to provide the harmful | toxic substance removal material with high efficiency and low pressure loss, without producing the lifetime reduction by compression.

  As a result of intensive studies to solve the above problems, the present inventors combined a first fiber having a fiber diameter of less than 1 μm and a second fiber having a fiber diameter of 1 μm or more, and the first fiber having a fiber diameter of less than 1 μm. By adjusting the content ratio, it was found that the collection efficiency, pressure loss, and life of harmful substances can be remarkably improved as compared with conventional filters, and the present invention has been completed.

  That is, according to the present invention, there is provided a hazardous substance removing material comprising a carrier containing a first fiber having a fiber diameter of less than 1 μm and a second fiber having a fiber diameter of 1 μm or more, wherein the first fiber and the second fiber There is provided a hazardous substance removing material characterized in that the ratio of fibers changes in the film thickness direction.

Preferably, the ratio of the first fibers to the second fibers increases from the side closer to the surface of the carrier toward the far side.
Preferably, the ratio of the first fibers to the second fibers varies within the range of 1: 9 to 9: 1.
Preferably, the carrier carries an antibody.

  According to another aspect of the present invention, there is provided a method for removing harmful substances, comprising removing harmful substances in the gas phase or liquid phase using the above-described hazardous substance removing material of the present invention.

  According to the present invention, it is possible to provide a harmful substance removing material that can remove particles in a gas phase or a liquid phase with high efficiency without causing a reduction in life due to compression, and that has a low pressure loss. According to the present invention, an air cleaner or a liquid cleaner that can efficiently remove harmful substances in a gas phase or a liquid phase can be produced, which is very useful in the industry.

Hereinafter, the present invention will be described in more detail.
The hazardous substance removing material of the present invention is a harmful substance removing material comprising a carrier containing a first fiber having a fiber diameter of less than 1 μm and a second fiber having a fiber diameter of 1 μm or more. The ratio of the fibers changes in the film thickness direction.

  The average fiber diameter of the first fiber used in the present invention is less than 1 μm, preferably 10 nm or more and less than 1 μm, more preferably 20 nm or more and 700 nm or less, and further preferably 30 nm or more and 500 nm or less. The average fiber diameter of the second fiber used in the present invention is 1 μm or more, preferably 1 μm or more and 500 μm or less, more preferably 1.5 μm or more and 100 μm or less, and further preferably 2 μm or more and 10 μm or less. In addition, an average fiber diameter can be calculated | required by measuring the diameter in the fiber in arbitrary places (for example, 300 places etc.) from the observation image of a scanning electron microscope (SEM), and arithmetically averaging it.

  In the present invention, it is preferable that the ratio of the first fiber to the second fiber increases from the side closer to the surface of the carrier toward the far side. The ratio of the first fiber to the second fiber is preferably changed within the range of 1: 9 to 9: 1, and more preferably within the range of 2: 8 to 8: 2. More preferably, it is changed within the range of 7 to 7: 3.

  The main fiber forming the carrier is preferably a fiber mainly composed of at least one of cellulose ester, vinylon, acrylic, and polyurethane. Further, as a main material for forming the carrier, fibers mainly composed of polyamide are also preferable. The main component as used in the field of this invention refers to the component which comprises 25% or more in the mass fraction in all the fibers.

  The cellulose ester in the present invention refers to a cellulose derivative in which the hydroxyl group of cellulose is esterified with an organic acid. Examples of organic acids used for esterification include fatty carboxylic acids such as acetic acid, propionic acid, and butyric acid, and aromatic carboxylic acids such as benzoic acid and salicylic acid. It may be used alone or in combination. Although there is no restriction | limiting in particular about the ester group substitution rate of the hydroxyl group of a cellulose, It is preferable that it is 60% or more.

  Among the main group of materials forming the carrier in the present invention, cellulose acylate fibers are desirable. Cellulose acylate refers to a cellulose ester in which some or all of the hydrogen atoms constituting the hydroxyl group of cellulose are substituted with acyl groups. Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group. These groups may be constituted by replacing only one kind, or two or more kinds of acyl groups may be mixed and substituted. The total acyl group substitution degree is preferably 2.0 to 3.0, more preferably 2.1 to 2.8, and particularly preferably 2.2 to 2.7. Among these, cellulose acetate, cellulose acetate propionate, or cellulose acetate butyrate that satisfies this degree of substitution is preferable, and cellulose acetate is most preferable. Cellulose acylate is generally known to have different solvents depending on the degree of esterification, but after preparing a carrier with cellulose acylate having a high esterification rate in advance, the surface is hydrophilized by alkali hydrolysis treatment or the like. May be.

  Although it is possible to form a sufficiently practical harmful substance removal material using only cellulose acylate fibers, polyester fibers, polyolefin fibers, polyamides are used for the purpose of further improving strength and dimensional stability. The carrier may be formed of a blended fiber such as a fiber or an acrylic fiber. When blended fiber is used, the mass fraction of the cellulose acylate fiber is preferably 50% or more, and more preferably 70% or more.

  Of the main group of materials forming the carrier in the present invention, it is also desirable to be a polyamide fiber.

  The polyamide in the present invention refers to a fiber made of a linear polymer having an amide bond in a chemical structural unit.

  Among polyamides, a linear chain that is a combination of an aliphatic diamine such as ethylenediamine, 1-methylethylenediamine, 1,3-propylenediamine, and hexamethylenediamine and an aliphatic dicarboxylic acid such as malonic acid, succinic acid, and adipic acid. Type aliphatic polyamides are preferred. Nylon 66 is particularly preferable.

  Fats using lactams such as ε-caprolactam and laurolactam, aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid, para-aminomethylbenzoic acid and the like alone or as a copolymer component in addition to the diamine and dicarboxylic acid. A group polyamide can also be used. In particular, nylon 6 produced by using ε-caprolactam alone is preferable.

  In addition to these, some or all of the aliphatic diamines used as raw materials are alicyclic diamines such as cyclohexanediamine, 1,3-bis (aminomethyl) cyclohexane, and 1,4-bis (aminomethyl) cyclohexane. An aliphatic polyamide using an alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid or the like may be used as an aromatic polyamide and / or as a dicarboxylic acid. .

  Furthermore, by using aromatic diamines such as aliphatic paraxylylenediamine (PXDA) and metaxylylenediamine (MXDA), and aromatic dicarboxylic acids such as terephthalic acid as partial raw materials, water absorption is reduced and elastic modulus is improved. Also included is a polyamide that achieves the above. Moreover, the polymer which has an amide bond in a side chain like polyacrylic acid amide, poly (N-methylacrylic acid amide), poly (N, N-dimethylacrylic acid amide), etc. may be sufficient.

  Most preferred of the polyamides is nylon 66 or nylon 6. Appropriate hygroscopicity derived from amide bonds, easy to orient the molecular chain consisting of long chain fatty acids of appropriate length, relatively high stretchability, high heat of fusion and large heat capacity It is difficult to melt in terms of kinetics (melt resistance), the flexibility of molecular chains consisting of long-chain fatty chains, and the property that fibrillation and kink bands do not easily occur due to the formation of hydrogen bonds between amide bonds. This is because the properties preferable for the carrier of the present invention such as flexibility can be utilized.

  A polyamide having an amide bond in the chemical structural unit in the side chain instead of the main chain can also be preferably used. Polyacrylamide such as poly (N-isopropylacrylamide), poly (N, N′-dimethylacrylamide), and poly (N-hexylacrylamide) can be used. In general, polymers with amide bonds in the side chains are highly hydrophilic and easily swell and deform, so they are hydrophobized by methods such as forming physical crosslinks or introducing alkyl groups using gelation. It is desirable.

  Similarly, for the purpose of improving strength and dimensional stability, the carrier may be reinforced with other appropriate structural materials such as metal, polymer material, ceramics and the like. These reinforcing materials are desirably used for portions other than the substantially outermost surface of the side surface to which the harmful substance removing material is supplied (for example, used on the opposite surface of the side surface or a core material).

  The vinylon in the present invention refers to a fiber made of a linear polymer containing 65% by mass or more of vinyl alcohol units, and having a moisture content of less than 7% after being left for 1 week or longer in an environment of temperature 20 ° C. and humidity 65%. . It may be a formalized hydroxyl group of vinyl alcohol, but it is a non-formalized fiber that has been subjected to water resistance treatment by a polymer such as a boric acid-crosslinked hydroxyl group or a known alkali spinning method or cooling gel spinning method. It may be. Components other than vinyl alcohol units may include ethylene chains, vinyl acetate chains, etc., but fibers formed from vinyl alcohol carriers are preferred. Furthermore, it is most desirable to be a non-formalized fiber by cooling gel spinning in that it is homogeneous and has a high degree of orientation and crystallinity, so that excellent mechanical properties and reliability can be obtained.

  Vinylon generally has high strength, high elastic modulus, moderate hydrophilicity, weather resistance, chemical resistance, adhesion and the like with respect to other fibers, and utilizes these preferable performances as a carrier of the present invention. be able to.

  The acrylic system in the present invention refers to a fiber containing 40% or more of acrylonitrile group repeating units, for example, a homopolymer of acrylonitrile, a nonionic monomer such as an acrylate ester, a methacrylate ester, or vinyl acetate; Examples include copolymers of acrylonitrile, copolymers of anionic monomers such as vinylbenzene sulfonic acid and allyl sulfonic acid and acrylonitrile, and copolymers of cationic monomers such as vinyl pyridine and methyl vinyl pyridine and acrylonitrile. So-called promix fibers formed from acrylonitrile and milk casein are also included in this category.

  In general, acrylic fibers are often produced by an organic wet spinning method. In this method, when the spinning stock solution forms a coagulated yarn in the coagulation bath, water as a coagulant enters the spinning stock solution spun from the nozzle, while the spinning solvent diffuses from the spun stock solution to the outside. At this time, the water and the organic solvent (DMF, DMAc, etc.) are mutually diffused, so that a polymer is precipitated and a coagulated yarn having a structure in which innumerable cavities are connected in a network form is formed. In addition, it is characterized by deformation of the fiber cross section formed by volume shrinkage due to diffusion of the solvent into the coagulation bath during the coagulation process and formation of irregularities by forming a macrofibril structure on the surface. These fine structures are preferable as the structure of the carrier used in the present invention in terms of improving the specific surface area and ease of carrying the antibody.

  The acrylic fiber used in the present invention varies depending on the composition of the raw material polymer, the spinning method, the post-treatment conditions in the production process, etc., but generally, it is easy to obtain a bulky fiber with moderate hydrophilicity and high weather resistance. There are advantages.

  The polyurethane used in the present invention refers to a fiber composed of a linear synthetic polymer in which the bonding portion between monomers or the bonding portion between base polymer materials is mainly urethane bonds. It is desirable that the polyurethane segment contains 85% or more by mass ratio. It is desirable to be a block copolymer of a segmented polyurethane composed of a soft segment having a low melting point and a soft molecular weight of up to several thousand, and a hard segment having a high melting point and rigidity and high cohesion. Polyethers such as polypropylene glycol and polytetramethylene glycol can be used as the soft segment, and urethane groups formed from 4,4'-diphenylmethane diisocyanate, m-xylene diisocyanate, and the like can be used as the hard segment. Polyurethane is generally characterized by high elasticity. It varies depending on the temporary structure of the polymer chain, such as the chemical structure and distribution of both segments, and on the difference in secondary structure resulting from differences in the spinning conditions, but it stretches well. It has characteristics such as high resilience, resistance to aging compared to rubber materials, and thin fibers can be obtained, and these properties can be utilized even when used as a carrier of the present invention.

  Regarding the mechanical properties and dimensional stability of the fibers constituting the carrier, it is desirable that the elongation at drying is 25% or more. Here, the elongation at drying refers to the breaking elongation in a tensile test at 20 ° C. of the fiber dried over a sufficiently long time. In general, it is preferable that the elongation at drying is 10% or more and that it is suitable for processing such as cloth making is 25% or more in order to prevent filter processing and breakage during practical use (leading to a decrease in filtration efficiency). % Or more is more preferable, and 35% or more is most preferable.

  The official moisture content of the fibers constituting the carrier is preferably 1.0% or more and less than 7.0%, more preferably 3.0% or more and less than 6.7%, and more preferably 5.0% or more and 6% or less. Most preferably, it is less than 5%. At the official moisture content in this area, the activity of the supported antibody can be expressed, and the carrier's mechanical strength, rigidity, and dimensional stability with respect to the environment (especially humidity) should be obtained. Can do.

  The moisture content referred to here is the official moisture content, and the official moisture content is the moisture content contained in the fiber when the fiber is left in an environment of 20 ° C. and a relative humidity of 65% for a long time. Point to. In the case of a blended fiber with other fibers, the official moisture content of the entire blended fiber is indicated.

  The surface of the fiber constituting the carrier preferably has a fine concavo-convex structure on the scale of several tens of nanometers to several micrometers. The shape of the irregularities may be a three-dimensional shape such as a groove or streak formed in a direction parallel to the fiber direction, or a groove or streak formed perpendicular to the fiber direction, that is, concentrically with respect to the axis. Three-dimensional shapes may be used, and these three-dimensional shapes formed at an arbitrary angle from the direction parallel to the fiber direction to the vertical direction may exist at an arbitrary ratio and density. Samples obtained by the known cellulose acetate fiber spinning method are known to form a chrysanthemum shape with an indefinite fiber cross section due to the formation of a skin layer on the surface layer and the depression of the skin layer accompanying solvent drying. This unevenness is also a preferred form in the present invention.

  The fine concavo-convex structure on the nanometer to micrometer scale may be a hole and / or a protrusion. The average diameter is preferably 50 nm to 1 μm of holes or protrusions. These vacancies and protrusions are formed in a spinning process by a method such as using a solution in which cavitation of a solution or a fine dispersoid is dispersed (for example, mixing with a slurry in which barium sulfate particles are dispersed), It can be formed in a subsequent step by a method such as hydrolysis of the group or surface oxidation treatment (for example, the surface of the fiber is celluloseized with an aqueous alkali solution and then the microcrater is expressed on the fiber surface by enzyme treatment).

  The fiber used in the present invention can be produced by a general production method such as melt spinning, wet spinning, dry spinning, wet drying spinning, or physical treatment (for example, strong mechanical shearing treatment using an ultra-high pressure homogenizer). In order to ensure stable quality, it is preferable to use dry spinning or wet dry spinning. In order to produce uniform fibers with an average fiber diameter of 100 nm or less, further processing techniques, 2005, 40, No. 2, 101, and 167; Polymer International, 1995, 36, 195- 201; Polymer Preprints, 2000, 41 (2), 1193; Journal of Macromolecular Science: Physics, 1997, B36, 169, etc. It is preferable to employ the electrospinning method.

  Solvents used for spinning include chlorinated solvents such as methylene chloride, chloroform and dichloroethane, amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, and ketones such as acetone, ethyl methyl ketone, methyl isopropyl ketone and cyclohexanone. Any solvent that dissolves the resin used for the synthetic resin fiber, such as a solvent, an ether solvent such as THF or diethyl ether, or an alcohol solvent such as methanol, ethanol, or isopropanol can be used. These solvents may be used alone or in combination of two or more.

  When the electrospinning method is employed, a salt such as lithium chloride, lithium bromide, potassium chloride, or sodium chloride may be further added to the resin solution.

It is desirable that the fibers constituting the carrier of the harmful substance removing material of the present invention have a structure in which a three-dimensional network is formed by partial adhesion. By adopting such a structure, it is possible to improve processing and practical mechanical resistance, and to improve the reliability of the hazardous substance removing material. In addition, the retention characteristics of the antibody of the present invention can be improved. The adhesion between fibers can be observed by a method such as SEM. The density of the bonding points between the fibers is preferably 10 or more per 1 mm square with respect to the projected surface area of the harmful substance removing material, and more preferably 100 or more.

  As a method for forming an adhesion point, it may be formed by an adhesion formed by a dry spinning method or a fusion point formed by a melt spinning method, or after spinning, addition of an adhesive, a plasticizing solvent, etc. You may perform the adhesion point formation process by. From the viewpoint of production cost, it is preferable to form adhesion points by a dry spinning method using an appropriate solution formulation.

  The carrier used in the present invention can carry an antibody. The antibody used in the hazardous substance removing material of the present invention is a protein that specifically reacts (antigen-antibody reaction) with a specific harmful substance (antigen), has a molecular size of 7 to 8 nm, and has a Y-shape. Having the molecular form of Of the Y-shaped molecular structure of an antibody, a pair of branch parts is called Fab and a trunk part is called Fc, and among these, a toxic substance is captured at the Fab part.

  The type of the antibody corresponds to the type of harmful substance that can be captured. Examples of harmful substances captured by antibodies include bacteria, molds, viruses, allergens, and mycoplasmas. Specifically, examples of bacteria include gram-positive bacteria, Staphylococcus (S. aureus and Staphylococcus epidermidis), micrococcus, anthrax, cereus, Bacillus subtilis, acne, and gram-negative bacteria. And Pseudomonas aeruginosa, Serratia, Sephacia, Streptococcus pneumoniae, Legionella, and Mycobacterium tuberculosis. Examples of molds include Aspergillus, Penicillius, and Cladosporium. Examples of the virus include influenza virus, coronavirus (SARS virus), adenovirus, rhinovirus and the like. Examples of allergens include pollen, mite allergen, cat allergen and the like.

  Examples of the method for producing the antibody include, for example, a method in which an antigen is administered to an animal such as a goat, horse, sheep, or rabbit, and a polyclonal antibody is purified from the blood, and a spleen cell and a cultured cancer cell of the animal to which the antigen is administered. Methods for purifying monoclonal antibodies from cell cultures and body fluids (such as ascites) of animals that have been transplanted with the cultures, purified antibodies from genetically modified bacteria, plant cells, or animal cell cultures into which antibody-producing genes have been introduced And a method of purifying a chicken egg antibody from egg yolk powder obtained by administering an antigen to a chicken to produce an immunized egg and sterilizing and spray-drying the egg yolk liquid. Among these, the method of obtaining an antibody from a chicken egg can easily obtain a large amount of the antibody and can reduce the cost of the harmful substance removing material.

  The antibody used in the hazardous substance removing material of the present invention is preferably a chicken egg antibody.

  The carrier constituting the hazardous substance removing material of the present invention is subjected to antibacterial processing such as coating containing an antibacterial agent and / or antifungal processing such as coating containing a fungicide. desirable. Antibodies are basically proteins, especially chicken egg antibodies are food, and may be accompanied by proteins other than antibodies, which are good food for bacteria and fungi to grow, but antibacterials are used as carriers. If processing and / or anti-mold processing is performed, the growth of such bacteria and molds is suppressed, and long-term storage can be performed.

  Examples of antibacterial / antifungal agents include organic silicon quaternary ammonium salts, organic quaternary ammonium salts, biguanides, polyphenols, chitosan, silver-supporting colloidal silica, and zeolite-supporting silver. The processing method includes impregnating or applying an antibacterial / antifungal agent to a fiber carrier, or a raw yarn raw cotton modified with an antibacterial / antifungal agent in the synthesis stage of the fibers constituting the carrier. There is a quality law.

  As a method for immobilizing an antibody on the carrier, the carrier is silanized using γ-aminopropyltriethoxysilane or the like, and then an aldehyde group is introduced onto the surface of the carrier with glutaraldehyde or the like. A method of covalent bonding, a method of immersing an untreated carrier in an antibody aqueous solution and immobilizing the antibody on the carrier by ionic bonding, an aldehyde group introduced into a carrier having a specific functional group, and the aldehyde group and the antibody A method of covalently bonding, a method of ionically binding an antibody to a carrier having a specific functional group, a method of introducing an aldehyde group after coating the carrier with a polymer having a specific functional group, and a method of covalently binding the aldehyde group and the antibody I can give you.

Here, examples of the specific functional group include an NHR group (R is any alkyl group other than H, methyl, ethyl, propyl, and butyl), NH ₂ group, C ₆ H ₅ NH ₂ group, and CHO group. , COOH group, and OH group.

  Also, there is a method in which the functional group on the surface of the carrier is converted to another functional group using BMPA (N-β-Maleimidopropionic acid) or the like, and then the functional group and the antibody are covalently bonded (SH group in BMPA). Are converted to COOH groups).

  Furthermore, there is a method in which a molecule (Fc receptor, protein A / G, etc.) that selectively binds to the Fc portion of the antibody is introduced onto the surface of the carrier and the antibody Fc is bound thereto. In this case, the Fab that captures the harmful substance faces outward with respect to the carrier, and the probability of contact of the harmful substance with the Fab increases, so that the harmful substance can be efficiently captured.

The antibody may be supported on a carrier via a linker. In this case, the degree of freedom of the antibody on the carrier is increased and access to harmful substances is facilitated, so that high removal performance can be obtained. Examples of the linker include bi- or higher-valent cross-linking reagents, specifically maleimide, NHS (N-Hydroxysuccinimidyl) ester, imide ester, EDC (1-Ethyl-3- [3-dimethylaminopropyl] carbodiimido), There is PMPI (N- [p-Maleimidophenyl] isocyanate), which is selective to target functional groups (SH group, NH ₂ group, COOH group, OH group) and non-selective. Moreover, the distance (space arm) between crosslinks also changes for every crosslink reagent, and it can select in the range of about 0.1 nm-3.5 nm according to the target antibody. From the viewpoint of efficiently capturing harmful substances, those that bind to the Fc of the antibody as a linker are preferred.

  As a method for introducing a linker, either a method in which a linker is bound to an antibody and then further bound to the antibody, or a method in which a linker is bound to a carrier and the antibody is bound to the linker on the carrier is possible. is there.

  The hazardous substance removing material of the present invention can be used for filters, masks, wipes and the like for air cleaners.

  When used as a filter for an air purifier, any known filter such as a prefilter for removing coarse dust, a dust removal filter, a photocatalytic filter exhibiting a deodorizing effect, an antibacterial filter for removing other harmful substances, a VOC adsorption filter, etc. It may be used in combination with a filter.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
Cellulose acetate (CA) was dissolved in a mixed solvent of acetone / dimethylacetamide = 2/1 to prepare a 12.5% by mass solution, and a 15% by mass DMF solution of polymethyl methacrylate (PMMA) was prepared. Each solution was simultaneously spun using the apparatus of FIG. 1 to produce a mixed film of fibers having different diameters. When the fiber diameter was measured by SEM, CA was 150 nm and PMMA was 3 μm. In addition, the spinning amount is adjusted so that the CA / PMMA ratio becomes 3/7 at the start of production, while the CA spinning amount is gradually increased while the PMMA spinning amount is gradually reduced and at the end of production, the CA / PMMA ratio is increased. Filter N-1 was prepared by adjusting the PMMA ratio to 7/3.

(Example 2)
Next, the spinning amount is adjusted so that the CA / PMMA ratio is 2/8 at the start of production, and the spinning amount of CA is gradually increased while the spinning amount of PMMA is gradually reduced to complete the production. At this time, the filter N-2 was prepared by adjusting the CA / PMMA ratio to 8/2.

(Comparative Example 1)
The spinning consideration was adjusted so that the CA / PMMA ratio was 5/5 from the start to the end of manufacture, and filter H-1 was prepared.

(Measurement of filter performance)
Each sample of N-1, N-2, and H-1 was punched to a diameter of 120 mm, set in a sample holder, and installed in a test duct having the same diameter. A particle generator (manufactured by TSI) is used to generate fine particles of 50 to 500 nm, and an electrostatic classifier (manufactured by TSI) is used to introduce fine particles having a specific particle diameter into the duct at a flow rate of 5.3 cm / sec. Introduced. The number of particles was counted using a condensed particle counter (manufactured by TSI) upstream and downstream of the sample holder, and the filter efficiency at a specific particle size was calculated from the ratio of the number of particles upstream and downstream. Said measurement was performed in the range of 50-500 nm of particle diameter, and average collection efficiency was computed.

  Moreover, the pressure loss at the time of measurement was also measured. Specifically, a differential pressure gauge was attached to a box partitioned by a sample having a diameter of 120 mm, clean air with a flow rate of 35 L / min was sent from the upstream side, and the differential pressure after 1 minute was measured to evaluate the pressure loss.

  Further, in the measurement using particles having a diameter of 100 nm, the amount of collected particles when the pressure loss reached 200 Pa was determined. The results are shown in Table 1.

FIG. 1 shows the spinning device used in the examples.

Explanation of symbols

1 Power supply device 2 Syringe 3 Needle 4 Collector 5 Polymer solution 6 Polymer solution 7 Fiber

Claims (5)

A harmful substance removing material comprising a carrier containing a first fiber having a fiber diameter of less than 1 μm and a second fiber having a fiber diameter of 1 μm or more, wherein the ratio of the first fiber to the second fiber is in the film thickness direction. Hazardous material removal material characterized by changes. 2. The hazardous substance removing material according to claim 1, wherein the ratio of the first fiber to the second fiber increases from a position closer to the surface of the carrier toward a position farther from the surface. The hazardous substance removing material according to claim 1 or 2, wherein a ratio of the first fiber to the second fiber is changed within a range of 1: 9 to 9: 1. The harmful substance removing material according to any one of claims 1 to 3, wherein the carrier carries an antibody. A method for removing harmful substances, comprising removing harmful substances in a gas phase or a liquid phase using the hazardous substance removing material according to any one of claims 1 to 4.