JP2021146302A - Filter medium, filter element, and filter medium manufacturing method - Google Patents

Abstract

To provide a filter medium that is small in pressure loss and has a deodorization function, and provide a filter element comprising the filter medium and a filter medium manufacturing method.SOLUTION: A filter medium of the present invention is provided in which the difference between the apparent density of a portion having the highest apparent density and the apparent density of a portion having the lowest apparent density in a cross section in the thickness direction of one fiber assembly A is 0.030 g/cm3 or more, and also a portion of low apparent density and a portion of high apparent density are present in the fiber assembly A. Accordingly, the filter medium that is small in pressure loss and has a deodorization function can be achieved because air is easy to pass in the portion of the low apparent density. Also, the filter medium of the present invention can be manufactured by that another fiber assembly A precursor is stacked on a main surface having deodorization particles of a fiber assembly B precursor and is pressurized after arranging deodorization particles on one main surface of the fiber assembly B precursor, and at least the fiber assembly A precursor is partially deformed in the thickness direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a filter medium having a deodorizing function, a filter element made of the filter medium, and a method for manufacturing the filter medium.

Conventionally, it has been required to purify the air by removing not only dust existing in the air but also volatile organic compounds (VOCs) that cause odors and allergies with a filter medium.

As a filter medium capable of removing such VOC, for example, as in the filter medium for an air filter of JP-A-2018-167155 (Patent Document 1), an adsorbent is arranged between layers formed by two non-woven fabrics, and the adsorbent can be used as an adsorbent. Filter media using activated carbon and inorganic porous materials are known. In the filter medium for an air filter of Patent Document 1, an adsorbent (activated carbon, an inorganic porous body) and a hot melt adhesive are stirred with a shaker, uniformly sprayed on a non-woven fabric, and heated to melt the hot melt adhesive. A filter medium for an air filter is manufactured by covering it with another non-woven fabric and hot-pressing it.

JP-A-2018-167155 (Claim 5 and the like)

However, since the filter medium disclosed in Patent Document 1 is compressed by a hot press, the two non-woven fabrics are dense and have a large pressure loss.

The present invention has been made under such circumstances, and an object of the present invention is to provide a filter medium having a deodorizing function, which has a small pressure loss, a filter element made of the filter medium, and a method for manufacturing the filter medium.

The invention according to claim 1 of the present invention is "a filter medium in which deodorizing particles are arranged between two fiber aggregates A and B, and at least one fiber aggregate A in a cross section in the thickness direction of the filter medium. There are a portion having a high apparent density and a portion having a low apparent density, and the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in the one fiber assembly A described above. The difference is 0.030 g / cm ³ or more, the filter medium. "

The invention according to claim 2 of the present invention is the filter medium according to claim 1, wherein the fiber aggregate B and the deodorizing particles are adhered to each other via an organic resin, and the organic resin is in the form of a sheet. be.

The invention according to claim 3 of the present invention states that "the fiber aggregate B and the deodorizing particles are adhered to each other via an organic resin, and the amount of the organic resin is 10 g / m ² or less, claim 1 or 2. The filter medium described in. ”.

The invention according to claim 4 of the present invention is "the filter medium according to any one of claims 1 to 3, wherein ^{the content of deodorizing particles is 100 g / m 2 or less."}

The invention according to claim 5 of the present invention is "the filter medium according to any one of claims 1 to 4, wherein the thickness of the filter medium is 0.70 mm or less."

The invention according to claim 6 of the present invention includes "a pleated filter medium according to any one of claims 1 to 5 and an outer frame provided on the peripheral edge of the pleated filter medium. It is a filter element. "

The invention according to claim 7 of the present invention describes "(1) a step of preparing a fiber aggregate B precursor and arranging deodorizing particles on one main surface of the fiber aggregate B precursor, (2) fiber assembly. Another fiber aggregate A precursor is laminated and pressurized on the main surface having the deodorized particles of the body B precursor, and at least the fiber aggregate A precursor is partially deformed in the thickness direction to form the fiber aggregate. The first aspect of claim 1, further comprising a step of forming a filter medium in which deodorizing particles are arranged between the fiber aggregate A derived from the A precursor and the fiber aggregate B derived from the fiber aggregate B precursor. A method for manufacturing a filter medium. "

The filter medium according to claim 1 of the present invention is the difference between the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in the cross section of one fiber aggregate A in the thickness direction. The pressure loss is 0.030 g / cm ³ or more, because the fiber assembly A has a part having a low apparent density and a part having a high apparent density, and the part having a low apparent density allows air to easily pass through. A small filter medium having a deodorizing function can be realized.

In the filter medium according to claim 2 of the present invention, the fiber aggregate B and the deodorizing particles are adhered to each other via the organic resin, and the organic resin is in the form of a sheet. However, the distribution of the organic resin is uniform, the deodorizing particles are uniformly distributed on the fiber aggregate B, and it is easy to realize a filter medium having good deodorizing performance.

In the filter medium according to claim 3 of the present invention, the fiber aggregate B and the deodorizing particles are adhered to each other via an organic resin, and the amount of the organic resin ^{is as small as 10 g / m 2} or less. Therefore, the filter medium is pleated. It is a filter medium that is easy to pleate and has excellent workability because the deodorizing particles and the organic resin are not adhered to each other and pleating is possible even if the force applied during pleating is small.

In the filter medium according to claim 4 of the present invention, since the content of ^{the deodorizing particles is as small as 100 g / m 2} or less, the deodorizing particles are scattered between the two fiber aggregates A and B. Therefore, a portion having a small apparent density of one of the fiber aggregates A tends to exist in a portion where the deodorizing particles do not exist, so that a filter medium having a small pressure loss can be easily realized.

Since the filter medium according to claim 5 of the present invention is a thin filter medium having a thickness of 0.70 mm or less, the filter medium can be installed even in a small space, and pleating is easy to perform and workability is improved. It is an excellent filter medium.

Since the filter element according to claim 6 of the present invention is pleated, the filter element has a wide filtration area of the filter medium and is excellent in dust and VOC collection efficiency.

In the method for producing a filter medium according to claim 7 of the present invention, deodorized particles are arranged on one main surface of the fiber aggregate B precursor, and then on the main surface having the deodorized particles of the fiber aggregate B precursor. Another fiber aggregate A precursor is laminated and pressurized to at least partially deform the fiber aggregate A precursor in the thickness direction to obtain the fiber aggregate A derived from the fiber aggregate A precursor and the fibers. This is a method capable of producing a filter medium having a deodorizing function with a small pressure loss by forming a filter medium in which deodorizing particles are arranged between fiber aggregates B derived from the aggregate B precursor.

It is explanatory drawing which shows an example of the cross section in the thickness direction of the filter medium of this invention. It is explanatory drawing which shows the cross section in the thickness direction of the filter medium of the prior art. It is a photograph which took the cross section in the thickness direction of the filter medium of Example 1 with a scanning electron microscope (magnification: 80 times). It is a photograph of the cross section of the filter medium of Comparative Example 1 in the thickness direction taken with a scanning electron microscope (magnification: 80 times).

The fiber aggregate A (1) constituting the filter medium of the present invention has a portion having a high apparent density and a portion having a low apparent density in the cross section in the thickness direction of the filter medium, and one of the fiber aggregates A (1) is described above. ), The difference between the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density is 0.030 g / cm ³ or more.

The filter medium of the present invention includes the fiber aggregate A (1) and the fiber aggregate B (2), and the fiber aggregate A (1) having a larger difference in apparent density in the cross section in the thickness direction of the filter medium is used. ).

FIG. 1 illustrates an example of a cross section in the thickness direction of the filter medium in which a portion having a high apparent density and a portion having a low apparent density exist in the fiber aggregate A (1) in the cross section in the thickness direction of the filter medium. In the filter medium shown in FIG. 1, the fiber aggregate A (1) constituting the filter medium follows the shape of the deodorizing particles (3), and the length of the fiber aggregate A in the thickness direction is not constant. In FIG. 1, the portion having the highest apparent density in the fiber aggregate A (1) is the portion (5) having the shortest length in the thickness direction in the fiber aggregate A (1), and the fiber aggregate A The portion having the lowest apparent density in (1) is the portion (6) having the longest length in the thickness direction in the fiber aggregate A (1). On the other hand, in the filter medium of the prior art, the length of the fiber aggregate A (1) in the thickness direction is constant and the length of the fiber aggregate A (1) in the thickness direction is constant, as illustrated in FIG. ) Is also constant.

In the cross section of the filter medium shown in FIG. 1 in the thickness direction, the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in the fiber aggregates A and B are determined by the following methods. Can be calculated.
(1) Calculate the basis weight of the fiber aggregate A or B. The basis weight refers to the mass per ^{1 m 2} of area on the widest surface.
(2) The filter medium is cut in the direction perpendicular to the main surface of the filter medium.
(3) Observe the cut surface of the filter medium cut in (2) with a microscope, and take three cross-sectional photographs of the filter medium. At this time, a cross-sectional photograph is taken so that the long side of the cut surface of the filter medium is 1 cm or more.
(4) From the cross-sectional photographs of the three filter media obtained in (3), a cross-sectional photograph of the length (mm) in the longest thickness direction of the fiber aggregate A or B perpendicular to the main surface of the filter media. Measure each, arithmetically average the measured values in the three cross-sectional photographs, and round off the fourth digit. Further, the length (mm) in the shortest thickness direction of the fiber aggregate A or B is also obtained in the same manner. The "main surface" in the present invention means the widest surface.
(5) The portion having the shortest thickness direction length (the part having the highest apparent density) and the longest thickness direction portion in the fiber aggregates A and B according to the following formula. Calculate the apparent density of (the part with the lowest apparent density).
d = {a / b} / 10 ³
d: Apparent density (g / cm ³ )
a: Metsuke of fiber aggregate (g / m ² )
b: Arithmetic mean value (mm) of the longest or shortest thickness direction of the fiber aggregate

When the difference between the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in the fiber aggregate A (1) constituting the filter medium of the present invention is 0.030 g / cm ³ or more. However, the larger the difference in apparent density, the easier it is for air to pass through the part with the lower apparent density. Therefore, the apparent density of the part with the highest apparent density and the apparent density of the part with the lowest apparent density more preferably 0.035 g / cm ³ or more, 0.040 g / cm ³ or more is more preferable. If the difference between the apparent density of the highest apparent density part and the apparent density of the lowest apparent density part is too large, the air permeability of the high apparent density part is too low, which causes an increase in pressure loss. Therefore, it is preferably 0.080 g / cm ³ or less.

Further, the length in the thickness direction of the portion having the highest apparent density in the fiber aggregate A (1) is 0.070 mm or more because the longer the length is, the higher the air permeability and the lower the pressure loss can be realized. Preferably, 0.090 mm or more is more preferable, and 0.110 mm or more is further preferable. As for the upper limit, if the length in the thickness direction is too long, the filtration performance of the filter medium may deteriorate, so that it is realistically 0.250 mm or less. The length of the portion of the fiber aggregate A (1) having the lowest apparent density in the thickness direction is preferably 1.00 mm or less, preferably 0.700 mm, because if it is too long, the filtration performance of the filter medium may deteriorate. The following is preferable, and 0.550 mm or less is more preferable. As for the lower limit, if it is too short, the air permeability may decrease and the filter medium may have a high pressure loss. Therefore, 0.100 mm or more is realistic.

Further, the apparent density of the portion having the highest apparent density in the fiber aggregate A (1) is 0.200 g / cm ³ or less because the lower the apparent density, the higher the air permeability and the lower the pressure loss can be realized. more preferably from 0.150 g / cm ³ or less, more preferably 0.130 g / cm ³ or less. As for the lower limit, 0.100 g / cm ³ or more is realistic because the filtration performance of the filter medium may deteriorate. If the apparent density of the portion having the lowest apparent density in the fiber aggregate A (1) is too low, the filtration performance of the filter medium may deteriorate. Therefore, 0.020 g / cm ³ or more is preferable, and 0. 030 g / cm ³ or more is more preferable, and 0.040 g / cm ³ or more is further preferable. As for the upper limit, if the apparent density is too high, the air permeability may decrease and the filter medium may have a high pressure loss. Therefore, 0.100 g / cm ³ or less is realistic.

The fiber aggregate A (1) constituting the filter medium of the present invention can be made of, for example, a non-woven fabric, a woven fabric, or a knitted fabric.

The components constituting the fiber aggregate A (1) include, for example, a polyolefin resin (polyethylene, polypropylene, polymethylpentene, a polyolefin resin having a structure in which a part of hydrocarbon is replaced with a cyano group or a halogen such as fluorine or chlorine. Etc.), styrene resin, polyether resin (polyetheretherketone, polyacetal, phenol resin, melamine resin, urea resin, epoxy resin, modified polyphenylene ether, aromatic polyetherketone, etc.), polyester resin (Polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, total aromatic polyester resin, unsaturated polyester resin, etc.), polyimide resin, polyamideimide resin, polyamide resin Resins (eg, aromatic polyamide resin, aromatic polyetheramide resin, nylon resin, etc.), resins having a nitrile group (eg, polyacrylonitrile, etc.), urethane-based resins, epoxy-based resins, polysulfone-based resins (polysulfone, polyether). Polyacrylonitrile resin obtained by copolymerizing a fluororesin (such as sulfone), a fluororesin (polytetrafluoroethylene, polyvinylidene fluoride, etc.), a cellulose resin, a polybenzoimidazole resin, and an acrylic resin (for example, an acrylic acid ester or a methacrylate ester). , Modaacrylic resin obtained by copolymerizing acrylonitrile with vinyl chloride or vinylidene chloride), vinylon fiber, and other known organic resins.

These organic resins may have either a linear polymer structure or a branched polymer structure, and the organic resin may be a block copolymer or a random copolymer, or the organic resin. The three-dimensional structure and the presence or absence of crystallinity are not particularly limited. Further, it may be a mixture of organic resins, and is not particularly limited.

One type of fiber constituting the fiber assembly A (1) is, for example, a melt spinning method, a dry spinning method, a wet spinning method, a direct spinning method (melt blow method, spun bond method, electrostatic spinning method, etc.), and a composite fiber. It can be obtained by a known method such as a method of extracting fibers having a small fiber diameter by removing the above organic resin and a method of beating the fibers to obtain divided fibers.

The fibers constituting the fiber aggregate A (1) may be composed of one type or a plurality of types of organic resins. As the fiber containing a plurality of types of organic resins, a composite fiber generally called a composite fiber, for example, a core-sheath type, a sea-island type, a side-by-side type, an orange type, or the like can be used.

The fiber diameter of the fibers constituting the fiber aggregate A (1) is not particularly limited, but the fiber diameter is preferably 1.0 to 30 μm, more preferably 1.5 to 20 μm, and 2.0 to 15 μm. Is more preferable. The longer the fiber length of the fibers constituting the fiber aggregate A, the more excellent the morphological stability of the fiber aggregate A. Therefore, 5 mm or more is preferable, 10 mm or more is more preferable, 20 mm or more is further preferable, and continuous fibers. It may be.

The fiber aggregate B (2) constituting the filter medium of the present invention can be the same constituent component and constituent fiber as the fiber aggregate A (1).

The fiber diameter and fiber length of the fibers constituting the fiber aggregate B (2) are not particularly limited, but the fiber diameter is preferably 1.0 to 50 μm, more preferably 3.0 to 40 μm, and 5 .0 to 30 μm is more preferable. The fiber length is preferably 3 mm or more, more preferably 4 mm or more, still more preferably 5 mm or more. It is realistic that the upper limit of the fiber length is 25 mm or less.

The deodorizing particles (3) constituting the filter medium of the present invention refer to particles having a deodorizing action, and examples thereof include activated carbon and inorganic particles such as silica gel and titanium oxide. The deodorizing particles constituting the filter medium of the present invention may be one type or two or more types. Among these, it is preferable that the deodorizing particles contain two types of activated carbon and silica gel because the filter medium can efficiently deodorize.

The shape and size of the deodorizing particles (3) are appropriately adjusted, and the deodorizing particles include, for example, spherical (substantially spherical or true spherical), fibrous, needle-shaped, flat plate-shaped, amorphous-shaped, polyhedral-shaped, or feather-shaped. It can be appropriately selected from the shape of the tetrapod and the like. The average particle size of the deodorized particles is preferably 0.10 to 1.5 mm, more preferably 0.11 to 1.2 mm, and most preferably 0.12 to 1.0 mm. preferable.

The particle size of the deodorized particles (3) in the present invention is the diameter of the deodorized particles that can be measured by taking an electron micrograph of the deodorized particles or an electron micrograph of the main surface of the filter medium having the deodorized particles. The average particle size means the average particle size of 10 deodorized particles. When the shape of the deodorizing particles shown in the electron micrograph is non-circular, the diameter of a circle having the same area as the deodorizing particles having the same shape shown in the electron micrograph is regarded as the diameter of the deodorizing particles.

Further, the deodorizing particles (3) may contain a compound that reacts with an odorous component, such as an amine compound or an acid hydrazide compound, and a compound that adsorbs the odorous component, for the purpose of improving the deodorizing efficiency.

The smaller the content of the deodorizing particles (3) contained in the filter medium of the present invention, the more the constituent fibers of the fiber aggregate A (1) are contained in the portion of the filter medium in which the deodorizing particles do not exist, and the fiber assembly Since a portion of the body A (1) having a small apparent density is likely to exist, a filter medium having a small pressure loss can be easily realized. Therefore, 100 g / m ² or less is preferable, 90 g / m ² or less is more preferable, and 80 g / m. ² or less is more preferable. On the other hand, if the content of the deodorizing particles is too small, the filter medium may not be able to sufficiently collect VOCs, and the deodorizing action of the filter medium may be insufficient. Therefore, 5 g / m ² or more is realistic.

In the filter medium of the present invention, it is preferable that the fiber aggregate B (2) and the deodorizing particles (3) are adhered to each other via the organic resin (4) so that the deodorizing particles (3) do not easily fall off from the filter medium. .. The shape of the organic resin (4) when the fiber aggregate B (2) and the deodorizing particles (3) are adhered to each other via the organic resin (4) may be, for example, a particle shape or a sheet shape. When the shape of the organic resin (4) is sheet-like, the distribution of the organic resin (4) is more uniform than when the organic resin (4) is in the form of particles, and the deodorized particles are placed on the fiber aggregate B (2). Is preferable because the particles are uniformly distributed and it is easy to realize a filter medium having good deodorizing performance.

The type of the organic resin (4) used for adhesion used in the present invention is appropriately selected and is not particularly limited, and known organic resins listed as components constituting the fiber aggregates A and B are used. Can be used.

When the amount of the organic resin (4) adhering the fiber aggregate B (2) and the deodorizing particles (3) in ^{the filter medium is 10 g / m 2} or less, the deodorizing particles (3) are pleated when the filter medium is pleated. And the organic resin (4) are loosened, and pleating is possible even if the force applied during pleating is small. Therefore, pleating is easy and the workability is excellent, and the air permeability of the filter medium is organic resin. A filter medium that is less likely to decrease due to (4) and has a small pressure loss is preferable. The smaller the amount of the organic resin (4) adhering the fiber aggregate B (2) and the deodorizing particles (3), the more the effect can be obtained. Therefore, 9 g / m ² or less is preferable, and 8 g / m / More preferably m ² or less. On the other hand, if the amount of the organic resin (4) is too small, the deodorizing particles (3) may easily fall off from the filter medium. Therefore, 1 g / m ² or more is preferable, 2 g / m ² or more is more preferable, and 3 g. / M ² or more is more preferable.

The fiber aggregate A (1) and the deodorizing particles (3) may be adhered to each other via an organic resin for the purpose of preventing the deodorizing particles (3) from falling off and improving the handleability of the filter medium. The shape of the organic resin is not particularly limited. The total amount of the organic resin adhering the deodorizing particles to the fiber aggregates A (1) and B (2) in the filter medium is such that the deodorizing particles are less likely to fall off when the amount is large, while the amount is too large to block the voids in the filter medium. Since the air permeability of the filter medium may decrease and the pressure loss may increase, and the workability of the filter medium may deteriorate, ² to 20 g / m 2 is preferable, 4 to 18 g / m ² is more preferable, and 6 ~ 16 g / m ² is more preferable.

Basis weight of the filter medium of the present invention is intended to suitably adjusted, preferably 50 to 200 g / ^{m 2,} more preferably 80~170g / ^{m 2,} more preferably 100 to 150 g / ^{m 2.}

Further, the thickness of the filter medium of the present invention is preferably 0.70 mm or less so that the filter medium can be installed even in a small space and the filter medium has excellent workability (pleating, etc.). The thinner the thickness, the more the effect can be obtained. Therefore, 0.68 mm or less is more preferable, and 0.66 mm or less is further preferable. On the other hand, if the filter medium is too thin, the shape retention may be inferior. Therefore, 0.30 mm or more is preferable, 0.40 mm or more is more preferable, and 0.50 mm or more is further preferable. The "thickness" of the filter medium and the fiber aggregate A precursor and fiber aggregate B precursor described later is measured by a high-precision digital measuring machine (registered trademark: Lightmatic (VL-50A) Mitutoyo Co., Ltd.). The arithmetic mean value of the distance between each main surface measured at five points when a load of 100 g is applied in the direction between the main surfaces, and the length in the thickness direction of the fiber aggregates A and B described above. Has a different definition.

It is preferable that at least one of the fiber aggregates A (1) and B (2) constituting the filter medium is electret-treated. Due to the electret treatment, submicron size and nano size fine dust, which is normally difficult to remove, can be collected by electrostatic force.

The filter medium of the present invention has two fiber aggregates A (1), B (2) and deodorizing particles (3), but other fiber aggregates other than the fiber aggregates A and B, and breathability. It may have a breathable material such as a porous film or a breathable foam.

Further, in the filter medium of the present invention, air may be passed so that the fiber aggregate A (1) is on the upstream side, or air may be passed so that the fiber aggregate B (2) is on the upstream side. However, if the air is passed so that the fiber aggregate B (2), which has a small difference in apparent density inside the fiber aggregate, is on the upstream side, the air flow is less likely to be biased in the filter medium, and dust and dust are efficiently generated. Since VOC can be collected, when using a filter medium, it is preferable to use it so that air is passed so that the fiber aggregate B side is on the upstream side.

The cross-sectional structure of the filter medium of the present invention in the thickness direction is not limited to that illustrated in FIG. 1, and in addition, for example, the fiber density in the fiber aggregate A even if the thickness is constant. However, even when there is an apparent density difference, the same action and effect as those of the filter medium having the cross-sectional structure illustrated in FIG. 1 can be obtained.

Further, the filter medium of the present invention may have a flat plate shape that has not been particularly processed, but the filter medium of the present invention is pleated and the filter medium is pleated, and an outer frame is provided on the peripheral edge portion. The filter element is preferable because it has a large filtration area and is excellent in collecting dust and VOC. The pleated height of the filter element of the present invention is preferably 5 to 50 mm, more preferably 10 to 45 mm, still more preferably 15 to 30 mm. The pleating interval of the filter element is preferably 2 to 20 mm, more preferably 3 to 15 mm, and even more preferably 3 to 10 mm. The outer frame of the filter element is the entire peripheral edge of the pleated filter medium (for example, when the filter medium is pleated and the plane shape is rectangular, the peripheral edge in the direction orthogonal to the pleated crease direction and the pleated crease. It may be on the peripheral edge in the direction parallel to the direction, or if the filter medium is pleated but only a part of the peripheral edge (for example, if the filter medium is pleated but the plane shape is rectangular, the pleated shape is fixed. For the purpose of holding, it may be located only at the peripheral edge in the direction orthogonal to the fold direction of the pleats).

Further, the pleated filter medium and the outer frame can be adhered by, for example, interposing a hot melt resin such as polyvinyl acetate between the outer frame and the filter medium. Further, as the outer frame, for example, an outer frame made of aluminum, aluminum alloy, stainless steel, various resins, paper, or non-woven fabric can be used.

The filter medium and the filter element as described above can be used as a filter unit by, for example, being housed in a frame-shaped filter frame.

Further, the filter medium of the present invention may be subjected to processing other than pleating. Examples of the processed filter medium of the present invention include a roll filter for a roll filter device in which the filter medium is processed so as to be wound and the filter medium is unwound and used.

Next, the method for producing the filter medium of the present invention will be described.

First, a fiber aggregate B precursor is prepared, and deodorized particles are arranged on one main surface of the fiber aggregate B precursor.

The fiber assembly B precursor can be composed of, for example, a non-woven fabric, a woven fabric, or a knitted fabric. When the fiber aggregate B precursor is a woven fabric or a knitted fabric, the fibers prepared as described above can be prepared by weaving or knitting to form a fiber aggregate B precursor. When the fiber aggregate B precursor is a non-woven fabric, for example, a dry non-woven fabric by a dry method, a wet non-woven fabric by a wet method, a spunbonded non-woven fabric by a direct spinning method, a melt blow non-woven fabric, an electrostatically spun non-woven fabric, or the like can be used. Among these, a non-woven fabric is preferable because the filter medium is excellent in processability (pleating, etc.), and among the non-woven fabrics, a wet non-woven fabric having a short fiber length and more excellent pleating workability is more preferable. ..

When the fiber aggregate B precursor is a non-woven fabric, as a method of binding the constituent fibers of the non-woven fabric, for example, a method of entwining with a needle or a water stream, a method of integrating the fibers with a binder, or a method of integrating the constituent fibers of the non-woven fabric with a binder. When the fiber web before binding contains fibers containing a thermoplastic resin, a method of melting the thermoplastic resin by heat-treating the fiber web to integrate the fibers with each other can be mentioned. .. As a method for heat-treating the fiber web, for example, a method of heating and pressurizing with a calendar roll, a method of heating with a hot air dryer, a method of irradiating infrared rays under no pressure to melt the thermoplastic resin fiber, and the like can be used. can.

The apparent density of the fiber aggregate B precursor is preferably 0.060 to 0.400 ^{g / cm 3} , preferably 0.080 to 0.080, so that a filter medium having excellent filtration performance and a filter medium having excellent processability can be produced. more preferably from 0.300 g / cm ^3, and even more preferably 0.100~0.200g / cm ^3. The basis weight of the fiber aggregate B precursor is preferably 10.0 to 100 ^{g / m 2} so that a filter medium having excellent filtration performance and a filter medium having excellent processability can be produced. more preferably from 0 g / ^{m 2,} and even more preferably 30.0~60.0g / ^{m 2.} Further, the thickness of the fiber aggregate B precursor is preferably 0.1000 to 0.600 mm, preferably 0.150 to 0.600 mm, so that a filter medium having excellent filtration performance and a filter medium having excellent processability can be produced. It is more preferably 500 mm, and even more preferably 0.200 to 0.400 mm.

Further, the amount of the deodorized particles (3) arranged is such that the fiber aggregate A precursor enters the portion where the deodorized particles (3) do not exist, and the cross section of the fiber aggregate A (1) constituting the filter medium in the thickness direction. ^{In the above, 100 g / m 2} or less is preferable, 90 g / m ² or less is more preferable, and 80 g / m ² or less is further preferable, so that there are a portion having a high apparent density and a portion having a low apparent density.

Further, the method of arranging the deodorizing particles (3) is not particularly limited. Further, for the purpose of preventing the deodorized particles (3) from falling off, the organic resin (4) is arranged on one main surface of the fiber aggregate B precursor before the deodorized particles (3) are arranged, and the fiber aggregate B is arranged. It is preferable to bond the precursor and the deodorizing particles (3). As a method of arranging the organic resin (4) and adhering the fiber aggregate B precursor and the deodorizing particles (3), for example, a sheet-shaped organic resin (4) is laminated or a particle-shaped organic resin (4) is laminated. The organic resin (4) is placed on one main surface of the fiber aggregate B precursor by spraying the particles, and then the organic resin (4) is dissolved by heat or high-temperature steam to dissolve the organic resin (4). The deodorizing particles (3) are arranged while the deodorizing particles (3) are being melted, and the deodorizing particles (3) are adhered by cooling, or the organic resin (4) melted by heat is attached to one of the fiber aggregate B precursors. A method of arranging on the main surface, arranging the deodorizing particles (3) while the organic resin (4) is dissolved, cooling and adhering the deodorizing particles (3), an organic resin dissolved in a liquid or a solvent ( By applying 4), the organic resin (4) is placed on one main surface of the fiber aggregate B precursor, and then the deodorizing particles (3) are placed before the organic resin (4) dries and solidifies. After that, a method of drying the organic resin (4) and adhering the deodorizing particles (3) can be mentioned.

Next, another fiber aggregate A precursor is laminated and pressurized on the main surface having the deodorized particles (3) of the fiber aggregate B precursor, and at least the fiber aggregate A precursor is partially partially formed in the thickness direction. The deodorized particles (3) are arranged between the fiber aggregate A (1) derived from the fiber aggregate A precursor and the fiber aggregate B (2) derived from the fiber aggregate B precursor. In addition, the filter medium of the present invention is produced.

Like the fiber aggregate B precursor, the fiber aggregate A precursor can be composed of a non-woven fabric, a woven fabric, a knitted fabric, or the like, but the thickness is easily changed among these, and the fiber aggregate A precursor is derived from the fiber aggregate A precursor. A non-woven fabric in which the difference between the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in the fiber aggregate A (1) ^{tends to be 0.030 g / m 2} or more is preferable, and among the non-woven fabrics, The difference in apparent density ^{tends to be 0.030 g / m 2} or more, and a dry non-woven fabric or melt-blown non-woven fabric having a certain thickness is more preferable, and an electlet treatment can be easily performed, and a filter medium having high dust collection performance can be realized. Therefore, melt blown non-woven fabric is more preferable.

At this time, the constituent fibers of the fiber aggregate A precursor enter into the portion where the deodorized particles (3) do not exist, and it is considered that the portion has a high apparent density in the cross section of the fiber aggregate A (1) in the thickness direction. ^{The apparent density of the fiber aggregate A precursor is 0.020 to 0.200 g / cm 3} so that a filter medium having a low hanging density can be easily manufactured and a filter medium having an excellent filtering performance can be easily manufactured. it is preferably, more preferably from 0.025~0.100g / cm ^3, and even more preferably 0.030~0.050g / cm ^3. Further, the thickness of the fiber aggregate A precursor is set so that a portion having a high apparent density and a filter medium having a low apparent density can be easily manufactured in the cross section of the fiber aggregate A (1) in the thickness direction. It is preferably 0.050 to 0.800 mm, more preferably 0.070 to 0.500 mm, and 0.100 to 0.400 mm so that a filter medium having excellent filtration performance can be easily produced. More preferred. Further, the basis weight of the fiber aggregate A precursor is preferably ^{5.0 to 30.0 g / m 2} so as to have excellent filtration performance of the filter medium and excellent processability of the filter medium. more preferably from 0~25.0g / ^{m 2,} and even more preferably 10.0~20.0g / ^{m 2.}

The pressurization method when another fiber aggregate A precursor is laminated and pressurized on the main surface having the deodorized particles of the fiber aggregate B precursor is not particularly limited, but for example, between two rolls. Examples thereof include a method of pressurizing through a laminated material and a method of pressing and pressurizing the laminated material. When the method of applying pressure by passing it between two rolls is adopted, at least the fiber aggregate A precursor, the deodorized particles, and the fiber aggregate are partially deformed in the thickness direction. It is preferable that the distance between the two rolls is narrower than the thickness of the laminate in which the body A precursors are laminated, and the distance between the two rolls is smaller than the total thickness of the fiber aggregate B precursor and the fiber aggregate A precursor. Is more preferable. The temperature at the time of pressurization may be heated without particularly heating, but if the temperature is too high, the constituent fibers of the fiber aggregate precursors A and B are dissolved to dissolve the fiber aggregate precursor A. , B may be blocked and the pressure loss may increase. Therefore, it is preferable to pressurize at a temperature lower than the lowest melting point among the constituent fibers of the fiber aggregates A and B precursors.

Further, for the purpose of preventing the deodorized particles (3) from falling off and improving the handleability of the filter medium, before stacking another fiber aggregate A precursor on the main surface having the deodorized particles of the fiber aggregate B precursor. , The organic resin is placed on the main surface having the deodorized particles of the fiber aggregate B precursor or on one main surface of the fiber aggregate A precursor, and the fiber aggregate B precursor and / or the deodorized particles (3). And the fiber aggregate A precursor are preferably adhered to each other. As a method of arranging the organic resin and adhering the fiber aggregate B precursor and / or the deodorized particles (3) to the fiber aggregate A precursor, the above-mentioned organic resin is arranged and the fiber aggregate B precursor and the fiber aggregate B precursor are bonded. A method similar to the method of adhering the deodorizing particles (3) can be adopted. Even if the adhesion between the fiber aggregate B precursor and the deodorizing particles (3) and the adhesion between the fiber assembly B precursor and / or the deodorizing particles (3) and the fiber assembly A precursor are performed at the same time, It may be done separately.

Hereinafter, the present invention will be specifically described with reference to Examples, but these do not limit the scope of the present invention.

(Example 1)
(Fiber assembly A precursor)
As the thermoplastic resin, polypropylene resin having a melting point of 160 ° C. is used, and a device consisting of an extruder, a gear pump, a melt blow mouthpiece, a compressed air generator and an air heater, a collecting conveyor, and a winder is used, and the grain size is 15.0 g. / ^{m 2,} a thickness of 0.350 mm, apparent density 0.043 g / cm ^3, the fiber diameter 2.0～5.0Myuemu, to produce a melt-blown nonwoven fabric of continuous fibers. Then, the melt blown nonwoven fabric was subjected to an electret treatment to prepare a fiber aggregate A precursor.
(Fiber assembly B precursor)
A fiber web ^{with a grain size of 35.0 g / m 2} composed of 60 mass% of polyethylene terephthalate fibers having a fiber diameter of 25 μm and a fiber length of 20 mm and 40 mass% of vinylon fibers having a fiber diameter of 15 μm and a fiber length of 20 mm by a wet method using an inclined wire method. Was produced. Then, the fiber web is impregnated with an acrylic binder and heat-treated by drying to form a fiber aggregate B precursor composed of a wet non-woven fabric ^{having a grain size of 45.0 g / m 2} , a thickness of 0.300 mm, and an apparent density of ^{0.150 g / cm 3.} Was produced.
(Deodorizing particles)
The average particle diameter of 0.30 .mu.m, activated carbon having a specific surface area of 1100 m ² / g, and an average particle diameter of 0.15 [mu] m, a specific surface area of 480m ² / g, was prepared spherical silica gel.
Next, the activated carbon and the silica gel were mixed at a mass ratio of 3: 1 to obtain deodorized particles of the present invention.
(Manufacturing of filter media)
A thermoplastic organic resin sheet having a melting point of 110 ° C. and made of a copolymerized polyamide ^{having a grain size of 5 g / m 2} was laminated on one main surface of the fiber aggregate B precursor.
Next, the deodorized particles were uniformly sprayed on the main surface having the thermoplastic organic resin sheet composed of the copolymerized polyamide of the fiber aggregate B precursor so that the total amount was 63 g / m ^2.
Then, a steam treatment at a pressure of 5 kg / cm ² and a temperature of 120 ° C. was performed for 7 seconds to melt the thermoplastic organic resin sheet, and the fiber aggregate B precursor and the deodorized particles were adhered to each other.
Further, a melted hot melt resin composed of polypropylene ^{having a grain size of 5 g / m 2} is sprayed on the main surface of the fiber aggregate B precursor having deodorized particles, and while the hot melt resin is melted. The fiber aggregate A precursor is laminated and passed between two rolls at room temperature with a distance between rolls of 0.65 mm to bond the fiber aggregate A precursor and deodorized particles, with a grain size of 133 g / m ² and a thickness of 133 g / m 2. A 0.65 mm filter medium was obtained. In the filter medium of Example 1, the length in the longest thickness direction in the fiber aggregate A is 0.238 mm, the length in the shortest thickness direction is 0.120 mm, and the portion having the highest apparent density in the fiber aggregate A. The apparent density of the part was 0.125 g / cm ³ , the apparent density of the portion having the lowest ^{apparent density was 0.063 g / cm 3} , and the difference was 0.062 g / cm ³ . The length of the fiber aggregate B in the longest thickness direction is 0.290 mm, the length in the shortest thickness direction is 0.276 mm, and the apparent density of the portion having the highest apparent density is 0.163 g / cm. ^3. The apparent density of the portion having the lowest apparent density was 0.155 g / cm ³ , and the difference was 0.008 g / cm ³ .
(Manufacturing of filter element)
The filter medium is used in a pleating machine, and an outer frame made of a non-woven fabric is attached to the entire peripheral edge of the filter medium using a hot melt resin to manufacture a filter element of 200 mm square, pleated height 19 mm, and pleated interval 3 mm. bottom.

(Comparative Example 1)
(Manufacturing of filter media)
A mixture of ^{63 g / m 2 of the same deodorized particles as in Example 1 and 10 g / m 2} of low-density polyethylene particles having a melting point of 98 ° C., which is the same as in Example 1, is sprayed on one main surface of the same fiber assembly B precursor as in Example 1, and then sprayed. The low-density polyethylene particles were melted by steam treatment at a pressure of 5 kg / cm ² and a temperature of 120 ° C. for 7 seconds to bond the fiber aggregate B precursor and the deodorized particles.
Further, the same fiber aggregate A precursor as in Example 1 is laminated on the main surface having the deodorized particles of the fiber aggregate B precursor while the low-density polyethylene particles are melted, and the distance between rolls is 0.65 mm. The fiber aggregate A precursor and the deodorizing particles were adhered to each other by passing them between two rolls at room temperature to obtain a filter medium having a ^{grain size of 133 g / m 2 and a thickness of 0.65 mm.} In the filter medium of Comparative Example 1, the length in the longest thickness direction in the fiber aggregate A is 0.188 mm, the length in the shortest thickness direction is 0.142 mm, and the portion having the highest apparent density in the fiber aggregate A. the apparent density 0.106 g / cm ^3, the apparent density of the lower portion of the most apparent density 0.080 g / cm ^3, the difference was 0.026 g / cm ^3. The length of the fiber aggregate B in the longest thickness direction is 0.283 mm, the length in the shortest thickness direction is 0.271 mm, and the apparent density of the portion having the highest apparent density is 0.166 g / cm. ^3. The apparent density of the portion having the lowest apparent density was 0.159 g / cm ³ , and the difference was 0.007 g / cm ³ .
(Manufacturing of filter element)
The filter medium is used in a pleating machine, and an outer frame made of a non-woven fabric is attached to the entire peripheral edge of the filter medium using a hot melt resin to manufacture a filter element of 200 mm square, pleated height 19 mm, and pleated interval 3 mm. bottom.

In the next pressure drop test, the filter media and filter elements of Examples and Comparative Examples were evaluated.

(Pressure loss test)
The filter media and filter elements of Examples and Comparative Examples ^{are set in a holder having an effective frontage area of 0.1 m 2} , and air is blown vertically from the fiber aggregate B side to the fiber aggregate A side at a surface wind speed of 3 m / min. The pressure difference between the upstream and downstream of the filter medium and the filter element was measured with a digital manometer MA2-04P differential pressure gauge manufactured by MODUS. The measurement was performed by arbitrarily sampling 5 points from one filter medium or filter element, and the average value was taken as the pressure loss (unit: Pa) of the filter medium and the filter element.

The results of the pressure loss test are shown in Table 1 below.

From the results in Table 1, the filter medium and filter element of Example 1 having the configuration of the present invention have the same fiber aggregate A precursor and the same fiber aggregate A precursor as compared with the filter medium and filter element of Comparative Example 1 having the configuration of the present invention. A filter medium and filter element with low pressure loss, which is produced by a fiber aggregate B precursor and is composed of the same amount of deodorized particles and an organic resin that adheres the same amount of deodorized particles and the fiber aggregate. It turned out that there was.

The filter medium and filter element according to the present invention can be used as a filter for purifying the air in the interior of the vehicle, but are particularly preferably used as an air filter for purifying the air in the interior of a vehicle such as an automobile or a railroad vehicle.

1 ... Fiber aggregate A
2 ... Fiber aggregate B
3 ... Deodorizing particles 4 ... Organic resin 5 ... The part having the shortest length in the thickness direction in the fiber aggregate A 6 ... The part having the longest length in the thickness direction in the fiber aggregate A

Claims (7)

A filter medium in which deodorizing particles are arranged between two fiber aggregates A and B.
In the cross section in the thickness direction of the filter medium, at least one of the fiber aggregates A has a portion having a high apparent density and a portion having a low apparent density.
A filter medium in which the difference between the apparent density of the portion having the highest apparent density and the apparent density of the portion having the lowest apparent density in one of the fiber aggregates A is 0.030 g / cm ^{3 or more.} The filter medium according to claim 1, wherein the fiber aggregate B and the deodorizing particles are adhered to each other via an organic resin, and the organic resin is in the form of a sheet. The filter medium according to claim 1 or 2, wherein the fiber aggregate B and the deodorizing particles are adhered to each other via an organic resin, and the amount of the organic resin is 10 g / m ^{2 or less.} The filter medium according to any one of claims 1 to 3, wherein the content of the deodorizing particles is 100 g / m ^{2 or less.} The filter medium according to any one of claims 1 to 4, wherein the thickness of the filter medium is 0.70 mm or less. A filter element comprising a pleated filter medium according to any one of claims 1 to 5 and an outer frame provided on a peripheral edge of the pleated filter medium. (1) A step of preparing a fiber aggregate B precursor and arranging deodorizing particles on one main surface of the fiber aggregate B precursor.
(2) Another fiber aggregate A precursor is laminated and pressurized on the main surface having the deodorized particles of the fiber aggregate B precursor, and at least the fiber aggregate A precursor is partially deformed in the thickness direction. A step of forming a filter medium in which deodorizing particles are arranged between the fiber aggregate A derived from the fiber aggregate A precursor and the fiber aggregate B derived from the fiber aggregate B precursor.
The method for producing a filter medium according to claim 1, wherein the filter medium has the above.

Images