JP4819367B2 - Manufacturing method of air filter sheet - Google Patents

Description

  The present invention provides volatile organic substances such as removal of ionic gaseous pollutants and TOC (Total organic compound) generated from clean rooms and manufacturing equipment such as semiconductor / liquid crystal manufacturing factories, automobile manufacturing factories, plastic manufacturing factories, printing factories, etc. Manufactures air filters used for removal of compounds (VOC), deodorization in refrigerators, freezers, toilets, hospitals, restaurants, storages, etc., decomposition of ozone generated in liquid crystal and semiconductor manufacturing factories, copiers, printers, etc. The present invention relates to an air filter sheet used for the purpose, a method for producing the air filter sheet, and an air filter obtained by molding the air filter sheet.

  For example, in advanced industries such as semiconductor manufacturing and liquid crystal manufacturing, it is important to control air and product surface contamination in a clean room in order to ensure product yield, quality, and reliability. In particular, in the semiconductor industry, as the degree of integration of products increases, control of ionic gaseous pollutants and TOC is indispensable in addition to control of particulate pollutants using HEPA, ULPA and the like.

Ionic gaseous pollutants include basic gases and acid gases. Among these, for example, ammonia, which is a basic gas, is considered to cause deterioration of resolution at the time of exposure and fogging of the wafer surface in an exposure process during semiconductor manufacturing. In addition, SO _X which is an acid gas causes stacking faults in the substrate and deteriorates device characteristics and reliability in a thermal oxide film forming process during semiconductor manufacturing.

As described above, ionic gaseous pollutants cause various difficulties in semiconductor manufacturing and the like, and therefore the concentration of ionic gaseous pollutants may be several ug / m ³ or less in a clean room used in semiconductor manufacturing or the like. It is desired.

  Further, in an automobile manufacturing factory, an organic solvent contained in a paint used for painting or the like is volatilized, and in a printing factory, an organic solvent contained in ink is volatilized. And when discharging the air in a factory to air | atmosphere, this organic solvent must be removed until it becomes the density | concentration below a discharge regulation value.

  Also, in semiconductor and liquid crystal manufacturing factories, an ultraviolet irradiation device is used for decomposing a photoresist solution or the like, and high-concentration ozone is generated upon irradiation with ultraviolet rays. Also, ozone water is used for cleaning semiconductors and liquid crystals. In addition, when printing with a copier or printer, ozone is generated when a high voltage is applied. Since ozone is harmful to the human body, it must be decomposed so that it is not discharged into the atmosphere.

  Therefore, conventionally, an air filter carrying a functional agent such as an ion exchange resin, activated carbon, zeolite, or a metal oxide catalyst has been used in order to remove an object to be removed from the air to be treated.

  For example, Japanese Patent Laid-Open No. 2001-259339 (Patent Document 1) discloses a powder ion exchange resin having a particle size of 0.1 to 100 μm and an ion exchange capacity of 0.5 to 10 meq / g for pulp and heat. An air filter medium made of paper mixed with a plastic resin or the like is disclosed.

  Further, the air filter is required to have the removal performance that lasts for a long time, that is, has a long life, in addition to the initial removal performance that the removal target can be removed to a certain concentration or less. Therefore, it is necessary to introduce a large amount of adsorbent into the air filter.

For example, JP 2003-24725 A (Patent Document 2) discloses an open cell structure in which a large number of air passages surrounded by a filter medium sheet containing a gas functional agent and a thermoplastic resin are integrated in parallel. The opening ratio in a cross section perpendicular to the air passage is 20% or more, the density of the filter medium sheet is 0.35 g / cm ³ or more, and the cell surface area per unit volume of the open cell structure is 1.0 m ² / L. An open cell structure for an air filter is disclosed. A gas functional agent is supported on the filter medium sheet at a high density.

JP 2001-259339 A JP 2003-24725 A

  Incidentally, in the air filter described in Japanese Patent Application Laid-Open No. 2001-259339, an ion exchange resin is held on a fiber such as pulp of a carrier (base material) by electrostatic force or friction force. For this reason, when the ratio of the ion exchange resin is increased, the ratio of the fibers is relatively decreased, and the amount of the ion exchange resin exceeds the amount that can be retained, so that the ion exchange resin is easily dropped. Therefore, in order to increase the amount of the ion exchange resin carried and make it difficult to drop off the ion exchange resin, the amount of fibers in the sheet constituting the air filter must be increased. As a result, the thickness of the sheet constituting the air filter is increased, the opening area per unit volume of the air filter is reduced, and the pressure loss is increased.

  Japanese Unexamined Patent Application Publication No. 2003-24725 discloses an open cell structure for an air filter in which a large number of types of functional agents are supported. Since the functional agent is supported by the same method as that of the air filter described in Japanese Patent No. 259339, there is a problem that the functional agent is likely to drop off when the supported amount is increased as described above.

  Accordingly, an object of the present invention is to provide a sheet for an air filter in which a large amount of the functional agent is carried and the functional agent is not easily removed from the carrier, and a manufacturing method thereof, and a high removal performance, a long life, and the functional agent is detached. It is to provide an air filter that is difficult to perform.

  Under such circumstances, the present inventors have conducted extensive studies, and as a result, (i) densification of the air filter sheet is performed by heating and compressing the fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered. As a result, it is possible to obtain a sheet for an air filter that is thin and has a high density, that is, a high loading amount per unit volume, and without increasing the weight ratio of the functional agent powder to the fibrous carrier, the functional agent. The amount of powder supported per unit volume can be increased, and (ii) the functional agent powder can be firmly adhered to the fibrous carrier by the thermoplastic resin. The inventors have found that even if the amount is large, it is possible to produce a sheet for an air filter that does not easily fall off, and the present invention has been completed.

That is, the present onset Ming, the fiber supporting, after applying or spraying a slurry containing the functional agent powder and a thermoplastic resin, or a fibrous support was immersed in a slurry containing the functional agent powder and a thermoplastic resin Thereafter, a drying treatment is performed to obtain a fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered, and then the air to which the fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered is heated and compressed. A method for producing a filter sheet,
The fibers constituting the fibrous carrier are inorganic fibers or a combination of inorganic fibers and organic fibers,
The inter-fiber porosity of the fibrous carrier is 50 to 95%,
The functional agent powder is an ion exchange resin powder, activated carbon powder or zeolite powder having an average particle size of 0.1 to 150 μm,
The content of the functional agent powder in the slurry is 10 to 40% by weight,
In the heat compression treatment, the compression ratio obtained by the following formula (1) of the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached is 10 to 50%,
The manufacturing method of the sheet | seat for air filters characterized by these is provided.
Compression rate (%) = {(D ₁ −D ₂ ) / D ₁ } × 100 (1)
(In the formula, D ₁ represents the thickness (mm) before the heat compression treatment, and D ₂ represents the thickness (mm) after the treatment.)

  Moreover, this invention (3) provides the air filter obtained by shape | molding the sheet | seat for air filters of the said this invention (1).

  The sheet for an air filter of the present invention has a large amount of the functional agent powder, and the functional agent powder is difficult to fall off from the carrier. In addition, the method for producing an air filter sheet of the present invention can produce an air filter sheet in which the amount of the functional agent powder supported is large and the functional agent is difficult to fall off from the carrier. In addition, since the air filter of the present invention has a large amount of the functional agent powder, the removal performance is high and the life is long, and the functional agent powder is difficult to fall off.

  The air filter sheet of the present invention is an air filter sheet obtained by heating and compressing a fibrous carrier to which a functional agent powder and a thermoplastic resin are attached.

  The fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered is heated and compressed to densify the air filter sheet, that is, the fibers constituting the fibrous carrier (hereinafter referred to as carrier fibers). The weight of the functional agent powder per unit volume of the air filter sheet can be increased without excessively increasing the weight ratio (functional agent powder / carrier fiber) to the functional agent powder. For this reason, the air filter sheet of the present invention has a large amount of the functional agent powder supported, and the functional agent powder is difficult to fall off.

  In the air filter sheet of the present invention, the thermoplastic resin functions as an adhesive that adheres the functional agent powders to each other and as an adhesive that supports the functional agent powders on the carrier fibers. Thus, the functional agent powder is firmly supported on the air filter sheet. In addition, the thermoplastic resin is present attached to the plurality of carrier fibers or enveloping the plurality of carrier fibers. The air filter sheet is produced by heating and compressing the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached. If the thermoplastic resin is absent, the carrier fiber is In order to return to the state before compression, the thickness of the air filter sheet after compression cannot be maintained. That is, the thermoplastic resin plays a role of supporting the functional agent powder on the carrier fibers, preventing separation of the carrier fibers existing in the vicinity, and maintaining the thickness of the air filter sheet. Also bears.

  The compression ratio when the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached is heated and compressed is preferably 10 to 50%, particularly preferably 15 to 35%. When the compression ratio is less than 10%, the loading amount of the functional agent powder tends to decrease, and when it exceeds 50%, the repulsive force of the carrier fiber increases and the thickness of the fibrous carrier is easily restored. . The method for obtaining the compression rate will be described later.

  The fibrous carrier according to the air filter sheet of the present invention is a woven fabric or a non-woven fabric composed of fibers, and is porous with a large number of voids (hereinafter also referred to as interfiber voids) between the fibers. It is woven or non-woven. Examples of the fiber (carrier fiber) include inorganic fibers such as silica / alumina fiber, silica fiber, alumina fiber, mullite fiber, glass fiber, rock wool fiber, carbon fiber; and polyethylene fiber, polypropylene fiber, nylon fiber, polyethylene Examples thereof include polyester fibers such as terephthalate fibers, and organic fibers such as polyvinyl alcohol fibers, aramid fibers, pulp fibers, and rayon fibers. Further, the carrier fibers may be a single type or a combination of two or more types. A combination of the inorganic fiber and the organic fiber is preferable from the viewpoint of increasing the mechanical strength of the air filter, and a combination of silica / alumina fiber or boron-less glass fiber and polyethylene terephthalate fiber is particularly preferable. In addition, it is preferable to use fibers other than pulp fibers as the carrier fibers in that the outgas is not contaminated by a ruptured or decomposed product of pulp fibers or an inorganic material such as sodium in the pulp.

  The average fiber diameter of the carrier fiber is not particularly limited, but is preferably 0.1 to 100 μm, particularly preferably 0.5 to 50 μm, and the average fiber length of the carrier fiber is preferably 0.1 to 50 mm, Especially preferably, it is 1-10 mm. When the average fiber diameter and the average fiber length are within the ranges, the mechanical strength of the fibrous carrier is increased.

  The functional agent powder is not particularly limited as long as it is a functional agent powder generally used for removing an object to be removed from the air to be treated. For example, ion-exchange resin powder, activated carbon powder, zeolite A powder, a metal oxide catalyst powder, etc. are mentioned, 1 type may be individual or 2 or more types of combinations may be sufficient.

  The average particle diameter of the functional agent powder is 0.1 to 150 μm, preferably 1 to 30 μm. If the average particle size is less than 0.1 μm, the size of the functional agent powder with respect to the gaps between the carrier fibers becomes too small, so that the functional agent powder easily falls off the fibrous carrier, When the thickness exceeds 150 μm, the weight per functional agent powder becomes too large, and it becomes difficult to obtain sufficient adhesive strength, and the functional agent powder easily falls off the fibrous carrier.

  The ion exchange resin powder according to the air filter sheet of the present invention is a functional agent mainly used for removing ionic gaseous contaminants. The ion exchange resin powder may be at least one of a cation exchange resin powder or an anion exchange resin powder, or may be both a cation exchange resin powder and an anion exchange resin powder. Among these, as a kind of cation exchange resin used for this cation exchange resin powder, a strong acidic cation exchange resin etc. are mentioned, for example. Moreover, as a kind of anion exchange resin used for this anion exchange resin powder, a strong basic anion exchange resin etc. are mentioned, for example.

  The ion exchange resin powder has an ion exchange capacity of usually 1 to 10 meq / g, preferably 3 to 6 meq / g. When the ion exchange capacity is less than 1 m equivalent / g, the reaction amount with the ionic gaseous pollutant becomes small, and the removal performance tends to deteriorate. On the other hand, if the ion exchange capacity exceeds 10 meq / g, the chemical stability of the ion exchange resin constituting the ion exchange resin powder is inferior, and the ion exchange groups are easily detached from the ion exchange resin powder itself.

In addition, when the air to be treated contains both basic gas (ammonia, amines, etc.) and acidic gas (SO _X , NO _X, etc.), the ion exchange resin powder is a cation exchange resin powder and an anion exchange. Both resin powders are preferred in that both basic gas and acidic gas can be removed.

  When the ion exchange resin powder includes a cation exchange resin powder and an anion exchange resin powder, the weight ratio of the cation exchange resin powder to the anion exchange resin powder is 20:80 to 80:20. If the weight ratio is outside the range of 20:80 to 80:20, the reaction amount of the cation exchange resin powder or the anion exchange resin powder with the ionic gaseous pollutant decreases. easy.

  The activated carbon powder according to the air filter sheet of the present invention is a functional agent mainly used for TOC removal, ozone decomposition, and the like. The activated carbon powder may be wood-based, coal-based, coconut shell-based or the like depending on the type of raw material, but is not particularly limited. Further, it may be activated carbon powder generally called impregnated charcoal to which an inorganic salt such as potassium carbonate is added. Among these, coconut shell-based activated carbon powder is preferable in terms of a good balance between performance and price. Further, in the case of TOC removal, those having a large specific surface area and a large pore volume are preferred, and in the case of ozonolysis, impregnated coal is preferred.

  The zeolite powder according to the air filter sheet of the present invention includes a hydrophilic one and a hydrophobic one. Hydrophilic zeolite powder is a functional agent mainly used for removal of ionic gaseous pollutants, deodorization, etc. Hydrophobic zeolite powder is a functional agent mainly used for removal of TOC, deodorization, etc. . The zeolite powder obtained by synthesis is usually a sodium-type zeolite whose counter ion at the acid site is sodium, but a part or all of the sodium ion is ion-exchanged with another metal ion, and is sodium-free. Or a dealuminated one may be used. Examples of the crystal structure include A-type zeolite, X-type zeolite, Y-type zeolite, beta-type zeolite, mordenite, ferrierite, ZSM-5 and the like. Of these, A-type zeolite, X-type zeolite, Y-type zeolite and ZSM-5 are preferred from the viewpoint of inexpensiveness.

  The metal oxide catalyst powder according to the air filter sheet of the present invention is a functional agent mainly used for decomposition, deodorization and the like of ozone. The metal oxide catalyst powder is not particularly limited, and examples thereof include manganese oxide, a mixed catalyst of manganese oxide-copper oxide, and a mixed catalyst of manganese oxide-cobalt oxide. On the surface of the metal oxide catalyst powder, malodorous substances such as triethylamine and methyl mercaptan are decomposed to deodorize, and ozone is oxidized to oxygen molecules.

  Further, the combined use of the metal oxide catalyst powder and the activated carbon powder is preferable as the functional agent powder for an exhaust gas purification filter of a printing machine such as a copying machine, a printer or a FAX.

The content of the functional agent powder per unit volume of air sheet filter of the present invention, 250 kg / ^{m 3} or more, preferably 400~700kg / ^{m 3,} in particular, the functional agent powder, the ion-exchange resin in powders, 400 kg / ^{m 3} or more, preferably 600~1000kg / ^{m 3,} the case of the zeolite powder, 500 kg / ^{m 3} or more, preferably 700~1200kg / ^{m 3,} the metal oxide catalyst powder for, 500 kg / ^{m 3} or more, preferably 700~1200kg / ^{m 3,} the case of the activated carbon powder, 250 kg / ^{m 3} or more, preferably 400~700kg / ^{m 3,} the metal oxide catalyst powder and the case of a combination of activated carbon powder (total of the metal oxide catalyst powder and the content of the activated carbon powder), 250 kg / m ³ or more, preferably 40 It is a ~700kg / ^{m 3.} When the content of the functional agent powder per unit volume of the air filter sheet is less than the above content, the air filter collection efficiency is lowered or the life is shortened. In the present invention, the volume of the air filter sheet refers to the apparent volume of the air filter sheet including inter-fiber gaps between the carrier fibers.

Further, when the functional agent powder is the ion exchange resin powder, the ion exchange capacity per unit volume of the air filter sheet is 1200 equivalent / m ³ or more, preferably 1500 to 6000 equivalent / m ³ , particularly preferably. Is 2000 to 4000 equivalents / m ³ .

  The weight ratio of the functional agent powder to the carrier fiber constituting the fibrous carrier (functional agent powder / carrier fiber) is 1 to 8, preferably 3 to 5. In particular, the functional agent powder is the ion. In the case of the exchange resin powder, it is 1 to 10, preferably 3 to 7, in the case of the zeolite powder, 1 to 15, preferably 3 to 8, and in the case of the metal oxide catalyst powder, 1 to 15, preferably Is 3-8, and in the case of the activated carbon powder, it is 1-8, preferably 3-5. When the metal oxide catalyst powder and the activated carbon powder are used in combination (the metal oxide catalyst powder and the activated carbon powder). Of the total weight / carrier fibers), 1-8, preferably 3-5. When the weight ratio of the functional agent powder is less than the above weight ratio, the supported amount of the functional agent powder decreases, and when the weight ratio exceeds the above weight ratio, the functional agent powder easily falls off.

  Conventionally, in order to increase the loading amount of the functional agent powder, the weight ratio of the functional agent powder to the carrier fiber has been increased. However, if the weight ratio of the functional agent powder to the carrier fiber is excessively increased in order to increase the loading amount of the functional agent powder, the gap between the carrier fibers to be supported by the functional agent powder and the fibrous carrier Less surface area. For this reason, the functional agent powder is not sufficiently supported and is easily detached from the fibrous carrier. On the other hand, in the air filter sheet of the present invention, the weight ratio of the functional agent powder to the carrier fiber is in the above range even though the amount of the functional agent powder supported is large. .

The content of the functional agent powder per unit area of the sheet the air filter, 50 g / m ² or more, preferably 80 to 200 g / m ^2, in particular, the functional agent powder, of the ion-exchange resin powder If, 100 g / ^{m 2} or more, preferably from 150 to 300 g / ^{m 2,} the case of the zeolite powder, 150 g / ^{m 2} or more, preferably 200 to 400 g / ^{m 2,} the case of the metal oxide catalyst powder , 150 g / ^{m 2} or more, preferably from 200 to 400 g / ^{m 2,} the case of the activated carbon powder, 50 g / ^{m 2} or more, preferably from 80 to 200 g / ^{m 2,} the metal oxide catalyst powder and activated carbon powder for combination (total content of the metal oxide catalyst powder and activated carbon powder), 50 g / ^{m 2} or more, preferably from 80 to 200 g / ^{m 2.} If the content of the functional agent powder per unit area of the air filter sheet is less than the above content, the initial performance of the air filter is lowered or the life is shortened.

Further, when the functional agent powder is the ion exchange resin powder, the ion exchange capacity per unit area of the air filter sheet is 300 m equivalent / m ² or more, preferably 400 to 2000 m equivalent / m ² , particularly preferably. Is 800-1500 meq / m ² .

  The thermoplastic resin is not particularly limited, and examples thereof include polyolefin resins such as polyethylene resin and polypropylene resin; polyester resins such as polyethylene terephthalate resin, acrylic resins, and fluorine resins. Among these, a polyethylene resin, a polyester resin, or an acrylic resin is preferable in terms of high adhesive force.

  The weight ratio of the functional agent powder to the thermoplastic resin (functional agent powder: thermoplastic resin) is 97: 3 to 60:40, preferably 95: 5 to 80:20. If the weight ratio of the functional agent powder is less than the above range, the area where the thermoplastic resin covers the surface of the functional agent powder increases, so that the removal performance of the air filter is likely to be low, and more than the above range. And the adhesion of the functional agent powder becomes insufficient, and the functional agent powder easily falls off.

  The thickness of the air filter sheet is 0.1 to 0.5 mm, preferably 0.2 to 0.3 mm. If the thickness of the air filter sheet is less than 0.1 mm, the mechanical strength of the air filter sheet tends to be low, and the moldability tends to deteriorate. Also, if the thickness of the air filter sheet exceeds 0.5 mm, the opening area of the cell formed when the honeycomb structure is made becomes small, so the ventilation speed in the cell increases and the removal performance tends to be low. .

  In addition, it is particularly preferable that the thickness of the air filter sheet is 0.2 to 0.3 mm because the moldability of the air filter sheet is improved. When forming a flat sheet into a corrugated sheet, if the thickness of the sheet is large, it becomes difficult to form a corrugated sheet with a short pitch, for example, a corrugated sheet with a pitch length of 3 mm or less. Therefore, in order to form a corrugated sheet with a short pitch, the thickness of the sheet has to be reduced. However, in the conventional air filter sheet, in order to reduce the thickness of the sheet, the thickness of the fibrous carrier had to be reduced. Therefore, the amount of the functional agent powder supported was reduced and the thickness was small. The performance of the air filter formed using the sheet was low. That is, in the conventional air filter sheet, improving the formability of the air filter sheet and increasing the loading amount of the functional agent powder have a conflicting relationship. On the other hand, since the air filter sheet of the present invention has a large amount of support per unit volume, the amount of the functional agent powder that can maintain the performance required for the air filter can be secured even if the sheet thickness is reduced. can do. That is, by using the sheet for an air filter of the present invention, an air filter having a corrugated honeycomb structure in which the amount of the functional agent powder supported and the pitch length is short can be manufactured.

  The content of the carrier fiber in the air filter sheet of the present invention is 10 to 50% by weight, preferably 15 to 30% by weight, and particularly when the functional agent powder is the ion exchange resin powder. 5 to 50% by weight, preferably 10 to 30% by weight, in the case of the zeolite powder, 1 to 50% by weight, preferably 5 to 30% by weight, and in the case of the metal oxide catalyst powder, 1 to 50% by weight, preferably 5 to 30% by weight. In the case of the activated carbon powder, 10 to 50% by weight, preferably 15 to 30% by weight, of the metal oxide catalyst powder and the activated carbon powder. In the case of combined use, it is 10 to 50% by weight, preferably 15 to 30% by weight. When the content of the carrier fiber in the air filter sheet is in the above range, the air filter sheet has high molding processability and the functional agent powder does not easily fall off. If the content of the carrier fiber in the air filter sheet is less than the above range, the functional agent powder tends to fall off, and if it exceeds the above range, the moldability tends to deteriorate. In addition, when the content of the carrier fiber in the air filter sheet is in the above range, most of the surface of the carrier fiber is covered with the functional agent powder.

  As described above, the air filter sheet of the present invention has a large amount of the functional agent powder such as the ion exchange resin powder, the activated carbon powder, the zeolite powder, or the metal oxide catalyst, and is suitable for the carrier fiber. Since the weight ratio of the functional agent powder is in the above range and the functional agent powder is firmly supported by the thermoplastic resin, it is difficult for the functional agent powder to fall off from the fibrous carrier.

  In the method for producing an air filter sheet of the present invention, (i) a slurry containing a functional agent powder and a thermoplastic resin is applied to a fibrous carrier (hereinafter also referred to as an application process) or spray (hereinafter, spray process). Or (ii) after immersing the fibrous carrier in a slurry containing a functional agent powder and a thermoplastic resin (hereinafter also referred to as immersion treatment), and then performing a drying treatment to obtain a functional agent. A fibrous carrier to which powder and a thermoplastic resin are adhered is obtained, and then the fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered is subjected to a heat compression treatment.

  The fibrous carrier according to the method for producing an air filter sheet of the present invention is a woven or non-woven fabric composed of carrier fibers, and is a porous woven or non-woven fabric having a large number of voids between the carrier fibers. The carrier fiber according to the method for producing an air filter sheet of the present invention is the same as the carrier fiber according to the air filter sheet of the present invention. Further, the carrier fibers may be a single type or a combination of two or more types. A combination of the inorganic fiber and the organic fiber is preferable in terms of improving the moldability of the air filter, and a combination of silica / alumina fiber or boronless glass fiber and polyethylene terephthalate fiber is particularly preferable.

  The inter-fiber porosity of the fibrous carrier according to the method for producing an air filter sheet of the present invention is not particularly limited, but is preferably 50 to 95%, particularly preferably 70 to 95%. The inter-fiber void ratio is the ratio of the apparent volume of the fibrous carrier to the portion of the fibrous carrier minus the volume of the carrier fibers (inter-fiber void). Say. When the inter-fiber porosity is within this range, the functional agent powder is supported not only on the outer surface of the fibrous carrier but also on the inter-fiber voids, so that the amount of the functional agent powder supported increases.

  The thickness of the fibrous carrier is not particularly limited, but is preferably 0.1 to 1.0 mm, particularly preferably 0.2 to 0.7 mm. When the thickness is less than 0.1 mm, the loading amount of the functional agent powder decreases, and when it exceeds 1.0 mm, the thickness of the air filter sheet becomes too large.

  Examples of the method for producing the fibrous carrier include a wet papermaking method and a dry molding method for the carrier fiber.

  The functional agent powder according to the method for producing an air filter sheet of the present invention is the same as the functional agent powder according to the air filter sheet of the present invention.

  The kind of the thermoplastic resin according to the method for producing an air filter sheet of the present invention is the same as the thermoplastic resin according to the air filter sheet of the present invention. Further, the form of the thermoplastic resin in the slurry is not particularly limited, and examples thereof include an emulsion or a dispersion which is a powder, fiber, or fine particle aqueous dispersion. The thermoplastic resin has, for example, an average particle diameter of 0.1 to 100 μm, preferably 0.5 to 50 μm in the case of powder, and an average fiber diameter of 0 in the case of fiber. 0.1 to 50 μm, preferably 1 to 20 μm, the average fiber length is 0.1 to 10 mm, preferably 0.3 to 5 mm, and in the case of emulsion or dispersion, the average particle size is 0.01 to 100 μm. The thickness is preferably 0.05 to 10 μm. When the average particle diameter exceeds 100 μm, or when the average fiber length exceeds 10 mm, the thermoplastic resin becomes difficult to enter the inter-fiber gap during the coating process, the spray process or the dipping process. This makes it difficult to obtain the effects of the present invention.

  The slurry can be prepared by adding the functional agent powder and the thermoplastic resin to water. The water is not particularly limited, and examples thereof include ion exchange water, distilled water, tap water, and industrial water. The slurry can also be prepared using an emulsion or dispersion in which the thermoplastic resin is dispersed in water, or a thermoplastic resin solution in which the thermoplastic resin is dissolved in an organic solvent. When a thermoplastic resin solution dissolved in the organic solvent is used, the thermoplastic resin solution dissolved in a polar solvent is preferable.

  The slurry can contain an inorganic binder. The inorganic binder is not particularly limited, and an inorganic binder that is usually used for supporting a functional agent powder of an air filter on a fibrous carrier can be appropriately used. With the inorganic binder, the functional agent powder and the thermoplastic resin are attached to the dried fibrous carrier.

  Moreover, this slurry can contain a filler, a dispersing agent, an antifoamer, a penetrant, etc. as needed.

  The content of the functional agent powder in the slurry is 10 to 40% by weight, preferably 15 to 35% by weight. In particular, when the functional agent powder is the ion exchange resin powder, 15 to 40% by weight. 20 to 35% by weight, in the case of the zeolite powder, 20 to 50% by weight, preferably 25 to 40% by weight, and in the case of the metal oxide catalyst powder, 20 to 50% by weight, preferably In the case of the activated carbon powder, it is 10 to 40% by weight, preferably 15 to 35% by weight. When the metal oxide catalyst powder and the activated carbon powder are used in combination (the metal oxide catalyst). The total content of the powder and the activated carbon powder) is 10 to 40% by weight, preferably 15 to 35% by weight. If the content of the functional agent powder in the slurry is less than the above range, the number of times of performing the coating treatment and the like is increased, the efficiency tends to deteriorate, and if the content exceeds the above range, the viscosity of the slurry is increased, The slurry is difficult to enter the interfiber gap.

  The content of the thermoplastic resin in the slurry is 0.1 to 20% by weight, preferably 0.5 to 15% by weight.

  The total amount of the functional agent powder and the thermoplastic resin in the slurry is 10 to 70% by weight, preferably 20 to 50% by weight. If the total amount of the functional agent powder and the thermoplastic resin is less than the above range, the number of times of performing the coating treatment and the like increases, and the efficiency tends to deteriorate. If the total amount exceeds the above range, the viscosity of the slurry is high. Thus, the slurry is difficult to enter the inter-fiber gap.

  Then, using the slurry, the coating treatment, the spraying treatment, or the dipping treatment is performed, and the slurry is adhered to the outer surface of the fibrous carrier and the interfiber gap. Examples of the method of performing the coating treatment include a method of continuously applying the slurry to the fibrous carrier using a roll coater or a flow coater. The method of performing the spray treatment includes, for example, Examples include a method of spraying the slurry onto the fibrous carrier by spray or the like capable of spraying the slurry in the form of a mist. Examples of the immersion treatment include, for example, an immersion tank in which the slurry is placed in the fibrous material. Examples thereof include a method of allowing the carrier to stand for a certain period of time, and a method of moving the fibrous carrier in the immersion tank. Moreover, the immersion time of the immersion treatment is not particularly limited, but is preferably 1 to 30 minutes, and particularly preferably 5 to 15 minutes. Among these, a method of applying using a roll coater is preferable in that the slurry can be uniformly attached to the outer surface of the fibrous carrier and the inter-fiber gap.

  Next, a drying process is performed. The drying temperature of the drying treatment is 60 to 150 ° C, preferably 80 to 130 ° C. The drying time of the drying treatment is not particularly limited, but is 5 to 120 minutes. By the drying treatment, moisture in the slurry can be removed, and the functional agent powder can be attached to the fibrous carrier with the thermoplastic resin or the binder.

  And the fibrous support | carrier with which this functional agent powder and thermoplastic resin are adhered is obtained by performing this drying process.

  Moreover, this application | coating process, this spray process or this immersion process, and this drying process can also be performed twice or more.

  In the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached, the weight ratio of the functional agent powder to the carrier fiber constituting the fibrous carrier (functional agent powder / carrier fiber) is 1 to 8, Preferably, it is 3-5, and in particular, when the functional agent powder is the ion exchange resin powder, it is 1-10, preferably 3-7, and when the zeolite powder is 1-15, preferably 3-3. In the case of the metal oxide catalyst powder, 1 to 15, preferably 3 to 8, and in the case of the activated carbon powder, 1 to 8, preferably 3 to 5, the metal oxide catalyst powder and When the activated carbon powder is used in combination (the total weight of the metal oxide catalyst powder and the activated carbon powder / carrier fiber), it is 1 to 8, preferably 3 to 5. When the weight ratio of the functional agent powder is less than the above weight ratio, the supported amount of the functional agent powder decreases, and when the weight ratio exceeds the above weight ratio, the functional agent powder easily falls off. The weight ratio is adjusted by appropriately selecting the conditions for the coating treatment, the spray treatment or the immersion treatment, such as the concentration of the functional agent powder and the thermoplastic resin in the slurry, the number of treatments, and the like. Is called.

  An example of a method for obtaining a fibrous carrier to which the functional agent powder and the thermoplastic resin are attached will be described with reference to FIGS. 1 and 2 are both schematic explanatory views of a method for producing a fibrous carrier to which a functional agent powder and a thermoplastic resin according to the present invention are attached using a roll coater. FIG. FIG. 2 is a view of the device 20 as viewed from one side, and FIG. 2 is a view of the coating device 20 as viewed from the other side, that is, a view as viewed from the side opposite to FIG.

  First, as shown in FIG. 1, the flat fibrous carrier 2 on the belt conveyor 21 is continuously fed out in the direction of arrow A, and an upper surface (first coating surface) of the flat fibrous carrier 2 by a roll coater 22. 31) The slurry 11 is applied and dried, and the functional agent powder and the thermoplastic resin are attached to the upper external surface (first application surface 31) and the inter-fiber gap of the flat fibrous carrier 2. A fibrous carrier 3a is obtained. Next, as shown in FIG. 2, the coated surface (first coated surface 31) of the fibrous carrier 3a to which the functional agent powder and the thermoplastic resin are attached is the lower surface, and the uncoated surface (second coated surface 32). 1 is set upside down in FIG. 1 so as to be on the upper surface, and the fibrous carrier 3a to which the functional agent powder and the thermoplastic resin are attached is continuously fed out in the direction of arrow B. 1, the slurry 11 is applied to the uncoated surface (second coated surface 32) and dried, and both external surfaces of the flat fibrous carrier 2 (first coated surface 31 and second coated surface 32). And the fiber support | carrier 3b by which this functional agent powder and thermoplastic resin are adhered to the space | gap between fibers is obtained.

  In addition, the drying process after apply | coating this slurry 11 to the fiber support | carrier 2 grade | etc., Is performed by applying a heat | fever or a hot air in the direction shown by the arrow X in the figure using the dryer 23. FIG. The drying temperature of the drying treatment is usually 50 to 130 ° C., and the drying time is usually 5 to 30 minutes.

  Next, heat compression treatment is performed. The heat compression treatment is a treatment in which the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached is compressed while being heated. This increases the content (supported amount) of the functional agent powder per unit volume of the air filter sheet.

The compressibility of the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached is not particularly limited, but is preferably 10 to 50%, particularly preferably 15 to 35%. When the compression ratio is less than 10%, it is difficult to increase the amount of the functional agent powder supported. . When the thickness before the heat compression treatment is D ₁ mm and the thickness after the treatment is D ₂ mm, the compression ratio is represented by the following formula (1):
{(D ₁ -D ₂ ) / D ₁ } × 100 (1)
It is calculated by.

  Although the heating temperature at the time of performing the heat compression treatment is different from the kind of the thermoplastic resin, it is preferably 80 to 170 ° C, particularly preferably 100 to 150 ° C.

  The method for performing the heat compression treatment is not particularly limited. For example, a method in which a fibrous carrier to which the functional agent powder and a thermoplastic resin are attached is passed through a calender roll heated to the heating temperature, the heating Examples thereof include a method of pressing the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached with a press machine heated to a temperature.

  In this way, by performing the heat compression treatment, the thermoplastic resin adheres to or wraps around the plurality of carrier fibers. As a result, it is possible to prevent the carrier fibers present in the vicinity from being separated from each other, so that the thickness of the compressed air filter sheet can be maintained. Further, by performing the heat compression treatment, the functional agent powder can be firmly adhered to the fibrous carrier by the thermoplastic resin.

  Without the thermoplastic resin powder, the fibrous carrier to which the functional agent powder after the heat compression treatment is adhered cannot maintain the thickness and tends to return to the thickness before the treatment. For this reason, it is difficult to increase the amount of the functional agent powder supported per unit volume of the air filter sheet. Therefore, in order to increase the loading amount of the functional agent powder per unit volume of the air filter sheet without using the thermoplastic resin powder, the weight ratio of the functional agent powder to the carrier fiber is increased. There must be. However, if the weight ratio is increased too much, the functional agent powder tends to fall off from the fibrous carrier. That is, when the thermoplastic resin is not used, there is a contradictory relationship between increasing the amount of the functional agent powder supported and making it difficult for the functional agent powder to fall off the fibrous carrier.

  On the other hand, the method for producing an air filter sheet of the present invention using the thermoplastic resin increases the loading amount of the functional agent powder without excessively increasing the weight ratio of the functional agent powder to the carrier fiber. be able to. Therefore, the air filter sheet obtained by the air filter sheet and the method for producing an air filter sheet of the present invention has a large amount of the functional agent powder and the functional agent powder is difficult to fall off. Further, by performing the heat compression treatment, the functional agent powder can be firmly adhered to the fibrous carrier by the thermoplastic resin, and therefore the functional agent powder is more difficult to fall off.

  The method for producing an air filter sheet of the present invention is suitably used for producing the air filter sheet of the present invention.

  The air filter of the present invention is obtained by molding the air filter sheet of the present invention using a conventional method. The shape of the air filter is not particularly limited. For example, the structure obtained by alternately laminating the corrugated air filter sheet and the flat air filter sheet (corrugated honeycomb structure), corrugated The pleated air filter sheet processed into a structure obtained by sequentially laminating the air filter sheet flat at right angles to the ventilation direction, etc., among these, corrugated honeycomb structure, Since the flow path of the air to be treated is parallel to the ventilation direction, the pressure loss is low, the peripheral device can be made compact, and the cost can be reduced.

  The corrugated honeycomb structure will be described with reference to FIGS. FIG. 3 is a schematic perspective view of a corrugated honeycomb structure used in the present invention. The air filter 42 is formed by alternately laminating flat air filter sheets 43 and corrugated air filter sheets 44, and between the flat air filter sheets 43 and the corrugated air filter sheets 44. In addition, a substantially semi-cylindrical cavity 46 extending in the continuous direction of the peak 45 of the corrugated air filter sheet is formed. In the chemical filter having the corrugated honeycomb structure having such a structure, when the air to be treated is introduced from the opening 47, the air to be treated can pass through the cavity 46.

  The flat air filter sheet 43 and the corrugated air filter sheet 44 are alternately stacked with the corrugated air filter sheet 44 as the center, thereby forming an air filter 42 having a corrugated honeycomb structure. In this case, the flat air filter sheet 43 and the corrugated air filter sheet 44 serving as the core are the upper and lower peaks 45 and 45 of the corrugated air filter sheet 44 (center core) and the flat air filter. The sheet 43 may be integrated by bonding with an adhesive, or the sheet 43 may be simply stacked without bonding or the like, and the stacked layer may be fixed in a frame or the like. Examples of the adhesive used for bonding the flat air filter sheet 43 and the corrugated air filter sheet 44 include thermoplastic resins such as acrylic.

  FIG. 4 is a schematic cross-sectional view taken along a plane parallel to the opening 47 in the air filter 42. In FIG. 4, the flat air filter sheet 43 and the corrugated air filter sheet 44 are formed by bonding a crest 45 of the corrugated air filter sheet 44 to the flat air filter sheet 43. The peak height of the air filter 42 used in the present invention (in FIG. 4, symbol h) is usually 0.5 to 10 mm, preferably 0.5 to 5 mm, and more preferably 1 to 2 mm. The pitch of the air filter 2 (in FIG. 4, symbol p) is usually 1 to 20 mm, preferably 1 to 5 mm, and more preferably 2 to 4 mm. In the present invention, it is preferable that the peak height and pitch are within the above ranges since the balance between the removal efficiency of the object to be removed and the pressure loss is good.

Further, when the functional agent powder carried on the air filter is an ion exchange resin powder, the ion exchange capacity per unit volume of the air filter is 800 equivalents / m ³ or more, preferably 1000 to 2000 equivalents / m is ^3.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

Example 1
(Preparation of mixed slurry)
100 parts by weight of a strongly acidic cation exchange resin and 10 parts by weight of polyethylene dispersion in terms of polyethylene resin solid content were mixed with 150 parts by weight of water to prepare a mixed slurry (A) having a solid content concentration of 40% by weight.
-Strongly acidic cation exchange resin; Diaion, manufactured by Mitsubishi Chemical Corporation, average particle size 20 μm, ion exchange capacity 5.0 m equivalent / g
Polyethylene dispersion: Chemipearl, manufactured by Mitsui Chemicals, solid content of polyethylene resin 45% by weight, average particle size of polyethylene resin 0.1 μm or less

(Preparation of air filter sheet)
A flat fibrous carrier 2 composed of 80% by weight of boronless glass fiber (average fiber diameter 13 μm, average fiber length 20 mm) and 20% by weight of polyethylene terephthalate resin fiber (average fiber diameter 10 μm, average fiber length 20 mm) The above mixed slurry (A) 11 is applied to the upper surface of a 0.4 mm thick and 90% inter-fiber void ratio using a roll coater 22 and further dried to 80 ° C. with a dryer 23 to obtain a flat fibrous material. A flat single-side coated fibrous carrier 3a having a strongly acidic ion exchange resin and a polyethylene resin adhered to the carrier 2 was wound up (FIG. 1). Next, after setting the single-side coated fibrous carrier 3a so that the coated surface becomes the lower surface, the upper surface on which the coated surface is not formed is coated with the mixed slurry (A) and dried in the same manner as described above. The flat double-side coated fiber carrier 3b to which the strongly acidic ion exchange resin and the polyethylene resin were attached was wound up.

Next, the flat double-side coated fiber carrier 3b was heated and compressed to 0.3 mm at 120 ° C. using a rolling device to obtain a flat air filter sheet (A). The compression rate at this time was 25%. The content of the strongly acidic ion exchange resin per unit volume of the flat air filter sheet (A) is 650 kg / m ³ , the ion exchange capacity per unit volume is 3250 equivalent / m ³ , and strongly acidic ions for the carrier fiber. The weight ratio of the exchange resin was 5, and the content of the carrier fiber in the air filter sheet (A) was 16% by weight.

(Production of air filter)
Next, the corrugated air filter sheet (A) was produced by passing the flat air filter sheet (A) between a pair of upper and lower corrugated corrugators. An acrylic emulsion was applied as an adhesive to the peak portion of the corrugated air filter sheet (A), and then the flat air filter sheet (A) was laminated and laminated. Lamination of the corrugated air filter sheet (A) and the flat air filter sheet is repeated so that the air flow direction is the same direction, and the core pitch as shown in FIGS. In FIG. 4, an air filter (A) having a corrugated honeycomb structure with a symbol p) of 2.5 mm and a peak height (in FIG. 4, symbol h) of 1.5 mm was obtained.

  The air filter A was cut to have a length of 100 mm × width of 100 mm × thickness of 40 mm, and this was fitted into an aluminum frame material.

The amount of the strongly acidic ion exchange resin supported per unit volume of the air filter (A) was 260 kg / m ³ , and the ion exchange capacity per unit volume was 1300 equivalent / m ³ .

(Measurement of air filter performance)
Using the air filter (A), the change over time in the ammonia removal rate and the life of the air filter (A) were measured under the following conditions. Although ammonia concentration in question the actual cleanroom is several [mu] g / m ^3, in order to accelerate the test, and the ammonia concentration in 240 [mu] g / m ^3. As a result, the life of the air filter (A) was 1500 hours. Moreover, when the pressure loss of this air filter (A) was measured on these conditions, it was 35 Pa. The life of the air filter was defined as the time when the ammonia removal rate decreased to 90%.

<Test conditions>
・ Aeration gas composition: Air containing ammonia 240 μg / m ³・ Aeration gas temperature and humidity: 23 ° C., 50% RH
-Gas to be removed: Ammonia-Ventilation air speed: 0.5 m / s

(Comparative Example 1)
(Preparation of mixed slurry)
A mixed slurry (A) was prepared in the same manner as in Example 1.

(Preparation of air filter sheet)
Flat fibrous carrier 2 composed of 80% by weight of boronless glass fiber (average fiber diameter 13 μm, average fiber length 20 mm) and 20% by weight of polyethylene terephthalate resin fiber (average fiber diameter 10 μm, average fiber length 20 mm) The above mixed slurry (A) 11 is applied to the upper surface (thickness 0.4 mm, inter-fiber void ratio 50%) using a roll coater 22, and further dried at 80 ° C. with a dryer 23 to obtain flat fibers. A flat single-side coated fibrous carrier 3a in which a strongly acidic ion exchange resin is supported on a porous carrier 2 was wound (FIG. 1). Next, after setting the single-side coated fibrous carrier 3a so that the coated surface is the lower surface, the mixed slurry (B) is coated and dried in the same manner as described above on the upper surface where the coated surface is not formed, The flat double-sided coated fibrous carrier 3b carrying a strong acid ion exchange resin was wound up to obtain a flat air filter sheet (B). The content of the strongly acidic ion exchange resin per unit volume of the flat air filter sheet (B) is 220 kg / m ³ , the ion exchange capacity per unit volume is 1100 equivalent / m ³ , and strongly acidic ions for the carrier fiber. The weight ratio of the exchange resin was 0.5, and the content of the carrier fiber in the flat air filter sheet (B) was 65% by weight.

(Production of air filter)
A flat air filter sheet (B) is used instead of the flat air filter sheet (A), and the peak height is 1.7 mm instead of 1.5 mm. 1 was performed to obtain an air filter (B).

  The air filter (B) was cut to have a length of 100 mm × width of 100 mm × thickness of 40 mm, and fitted into an aluminum frame member.

The amount of strongly acidic ion exchange resin supported per unit volume of the air filter (b) was 100 kg / m ³ , and the ion exchange capacity was 500 equivalents / m ³ .

(Measurement of air filter performance)
It replaced with the air filter (A) and performed by the method similar to Example 1 except setting it as the air filter (B). As a result, the life of the air filter (B) was 600 hours. Further, when the pressure loss of the air filter (B) was measured under these conditions, it was 45 Pa.

(Comparative Example 2)
(Preparation of mixed slurry)
100 parts by weight of the strongly acidic cation exchange resin used in Example 1 and 10 parts by weight of colloidal silica in terms of silica solid content are mixed with 140 parts by weight of water, and a mixed slurry (B) having a solid content concentration of 40% by weight. Was prepared.
Colloidal silica: Snowtex, manufactured by Nissan Chemical Co., Ltd., silica solid content 30% by weight

(Preparation of air filter sheet)
A flat fibrous carrier 2 composed of 80% by weight of boronless glass fiber (average fiber diameter 13 μm, average fiber length 20 mm) and 20% by weight of polyethylene terephthalate resin fiber (average fiber diameter 10 μm, average fiber length 20 mm) The mixed slurry (B) 11 is applied to the upper surface of 0.4 mm in thickness and 97% inter-fiber void ratio using a roll coater 22 and further dried at 80 ° C. with a dryer 23 to obtain a flat fibrous material. A flat single-side coated fibrous carrier 3a having a strongly acidic ion exchange resin attached to the carrier 2 was wound up (FIG. 1). Next, after setting the single-side coated fibrous carrier 3a so that the coated surface is the lower surface, the mixed slurry (B) is coated and dried in the same manner as described above on the upper surface where the coated surface is not formed, The flat double-side coated fiber carrier 3b to which the strongly acidic ion exchange resin was adhered was wound up.
Next, the flat double-side coated fibrous carrier 3b was heated and compressed to 0.3 mm at 120 ° C. using a rolling device to obtain a flat air filter sheet (C). After the heat compression, the thickness of the flat air filter sheet (C) was restored to 0.4 mm. Therefore, the compression rate at this time was 0%. The content of the strongly acidic ion exchange resin per unit volume of the flat air filter sheet (C) after the thickness is restored is 525 kg / m ³ , and the ion exchange capacity per unit volume is 2625 equivalent / m ³ , The weight ratio of the strongly acidic ion exchange resin to the carrier fiber was 16, and the content of the carrier fiber in the air filter sheet (C) was 4% by weight.

(Production of air filter)
An attempt was made to produce a corrugated air filter sheet (C) by passing the air filter sheet (C) between a pair of upper and lower corrugators and passing the flat air filter sheet (C). The removal of the ion exchange resin from the sheet (C) was severe and processing was difficult, and as a result, a filter could not be produced.

It is typical explanatory drawing seen from one side of the method of manufacturing the fibrous support | carrier to which the functional agent powder and the thermoplastic resin are adhered using a roll coater. It is typical explanatory drawing seen from the other side of the method of manufacturing the fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered using a roll coater. It is a typical perspective view of a corrugated honeycomb structure. 5 is a schematic cross-sectional view of the air filter 42 cut along a plane parallel to the opening 47. FIG.

Explanation of symbols

2 Fiber carriers 3a and 3b Fiber carrier 11 on which functional agent powder and thermoplastic resin are adhered 11 Slurry 20 Coating device 21 Belt conveyor 22 Roll coater 23 Dryer 31 First coating surface
32 Second coating surface 42 Air filter 43 Flat air filter sheet 44 Corrugated air filter sheet 45 Mountain portion 46 Cavity 47 Opening portion h Mountain height p Pitch

Claims (1)

After applying or spraying the slurry containing the functional agent powder and the thermoplastic resin on the fibrous carrier, or after immersing the fibrous carrier in the slurry containing the functional agent powder and the thermoplastic resin, a drying treatment is performed, A fiber carrier to which a functional agent powder and a thermoplastic resin are adhered is obtained, and then the fibrous carrier to which the functional agent powder and the thermoplastic resin are adhered is heated and compressed by a method for producing a sheet for an air filter. Yes,
The fibers constituting the fibrous carrier are inorganic fibers, or a combination of inorganic fibers and organic fibers,
The inter-fiber porosity of the fibrous carrier is 50 to 95%,
The functional agent powder is an ion exchange resin powder, activated carbon powder or zeolite powder having an average particle size of 0.1 to 150 μm,
The content of the functional agent powder in the slurry is 10 to 40% by weight,
In the heat compression treatment, the compression ratio obtained by the following formula (1) of the fibrous carrier to which the functional agent powder and the thermoplastic resin are attached is 10 to 50%,
The manufacturing method of the sheet | seat for air filters characterized by these.
Compression rate (%) = {(D ₁ −D ₂ ) / D ₁ } × 100 (1)
(In the formula, D ₁ is the thickness (mm) before the heat compression treatment, and D ₂ is the thickness (mm) after the treatment.)

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