JP2017166106A - Fiber aggregate, cotton-like material, spun yarn, felt, nonwoven fabric, filter unit, and method for producing filter unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber aggregate having a relatively large surface area per unit volume.SOLUTION: A fiber aggregate according to one embodiment of the present invention is mainly composed of fluororesin fibers. The fluororesin fibers preferably include a fiber having an edge. The fluororesin fibers preferably have a fine fiber structure including knots. The fluororesin fibers are preferably fibers obtained by breaking a stretched polytetrafluoroethylene porous body. The porosity of the fiber aggregate is preferably 80 vol.% or more. A cotton-like material according to another embodiment of the present invention is a cotton-like material using the fiber aggregate. A spun yarn according to another embodiment of the present invention is a spun yarn using the fiber aggregate. Felt according to another embodiment of the present invention is felt using the fiber aggregate. A nonwoven fabric according to another embodiment of the present invention is a nonwoven fabric using the fiber aggregate.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fiber assembly, a cotton-like body, spinning, felt, nonwoven fabric, a filter unit, and a method for producing the filter unit.

  As a filter for capturing fine particles in a gas, a filter using a porous film having a fine and uniform pore diameter is known.

  As a filter using such a porous membrane, the porous membrane is disposed so that the surface of the porous membrane having a thickness of about 100 μm is substantially perpendicular to the gas flow, and the fine particles passing through the filter Among them, a configuration for capturing fine particles having a particle size larger than the pore size of the porous membrane is known (see Japanese Patent Application Laid-Open No. 2004-195349). In this conventional filter, when the particle size of the fine particles to be captured is reduced, it is necessary to reduce the pore size of the porous membrane in accordance with the particle size, and the pressure loss is increased. For this reason, energy for increasing the pressure of the gas passing through the filter is required.

  In view of this, as a filter that can capture fine particles having a small particle diameter and reduce pressure loss, for example, a filter having a honeycomb-structure cavity has been proposed (see Japanese Patent Application Laid-Open No. 2005-46792). This conventional filter forms a honeycomb structure using paper coated with an ion exchange resin. The filter captures fine particles in the paper by allowing gas to pass through the cavities of the honeycomb structure. By constituting in this way, since gas does not permeate the paper, pressure loss can be reduced as compared with a filter using a porous membrane arranged substantially perpendicular to the gas flow.

JP 2004-195349 A JP 2005-46792 A

  However, even in the conventional filter having the above honeycomb structure, when the particle diameter of the fine particles to be captured is 100 nm or less, the filter surface area per unit volume is insufficient, so the filter length needs to be increased, and the pressure loss Reduction effect is not enough. For this reason, the high pressure energy of the gas which passes a filter is needed.

  This invention is made | formed based on the above situations, and aims at provision of the fiber assembly with a comparatively large surface area per unit volume.

  The fiber assembly which concerns on 1 aspect of this invention has a fluororesin fiber as a main component.

  The cotton-like body according to another embodiment of the present invention is a cotton-like body using the fiber assembly.

  The spinning according to another aspect of the present invention is a spinning using the fiber assembly.

  A felt according to another embodiment of the present invention is a felt using the fiber assembly.

  The nonwoven fabric which concerns on another one aspect | mode of this invention is a nonwoven fabric using the said fiber assembly.

  A filter unit according to another aspect of the present invention includes a casing having a pair of opposed mesh openings, and a cotton-like body disposed in the casing, and the cotton-like body is the fiber assembly. It is a cotton-like body using.

  The manufacturing method of the filter unit which concerns on another one aspect | mode of this invention comprises the process of obtaining a fiber assembly by crushing a fluororesin film, and the process of arrange | positioning the said fiber assembly in a casing.

  The fiber assembly of the present invention has a relatively large surface area per unit volume. Therefore, the fiber assembly of the present invention can be suitably used for a fine particle capturing filter and the like.

It is a photograph which shows the fiber assembly of one Embodiment of this invention. It is a photograph which shows an expanded PTFE fiber. It is a photograph which shows the fine fiber structure which has the nodule of the expanded PTFE fiber expanded 2000 times. It is typical sectional drawing of the filter unit of one Embodiment of this invention. It is a photograph which shows a mode that the expanded PTFE porous body is crushed.

[Description of Embodiment of the Present Invention]
The fiber assembly which concerns on 1 aspect of this invention has a fluororesin fiber as a main component.

  Since the fiber assembly is mainly composed of fluororesin fibers, the strength of the fibers is relatively high. For this reason, since the diameter of a fluororesin fiber can be made comparatively small, the said fiber assembly can enlarge the surface area per unit volume.

  The fluororesin fiber may include an edged fiber. Thus, by including the fiber with an edge in the said fluororesin fiber, the surface area of fiber itself can be further enlarged compared with the case where there is no edge.

  The fluororesin fiber may have a fine fiber structure including a nodule. Thus, by making the said fluororesin fiber have the fine fiber structure containing a nodule, since it becomes easy to raise the porosity of the said fiber assembly, the surface area per unit volume of the said fiber assembly can be enlarged.

  The fluororesin fiber may be a fiber obtained by crushing a stretched polytetrafluoroethylene porous body. Examples of fibers using polytetrafluoroethylene include extruded and stretched fibers and electrospun fibers, but these fibers have no edges and have a relatively small surface area. In contrast, a fiber obtained by crushing a stretched polytetrafluoroethylene porous body has an edge and a fine fiber structure including a nodule. Further, the fiber obtained by crushing the stretched polytetrafluoroethylene porous body has a smaller fiber diameter than the extruded and stretched fiber, and is more porous than the electrospun fiber. For this reason, the surface area per unit volume can be further increased by using the fluororesin fiber as a fiber obtained by crushing a stretched polytetrafluoroethylene porous body. Moreover, since polytetrafluoroethylene has excellent chemical resistance, heat resistance, and the like, the fiber assembly is excellent in weather resistance.

  The porosity of the fiber assembly is preferably 80% by volume or more. Thus, by making the said porosity into more than the said minimum, the pressure loss at the time of gas passing can be reduced, maintaining the surface area per unit volume.

  The cotton-like body according to another embodiment of the present invention is a cotton-like body using the fiber assembly.

  The cotton-like body can increase the surface area per unit volume by using the fiber assembly. For this reason, the said cotton-like body can be used suitably for a particulate capture filter, a sound absorbing material, a heat insulating material, a bedding, a feather for clothing, a medical filler, and the like.

  The spinning according to another aspect of the present invention is a spinning using the fiber assembly.

  The spinning can increase the surface area per unit volume by using the fiber assembly. Therefore, the spinning can be suitably used for medical sutures, medical patches, spool filters, protective clothing, and the like.

  A felt according to another embodiment of the present invention is a felt using the fiber assembly.

  The felt can increase the surface area per unit volume by using the fiber assembly. For this reason, the felt can be suitably used for a particulate trapping filter, a sound absorbing material, a heat insulating material, a medical filler, and the like.

  The nonwoven fabric which concerns on another one aspect | mode of this invention is a nonwoven fabric using the said fiber assembly.

  The said nonwoven fabric can enlarge the surface area per unit volume by using the said fiber assembly. For this reason, the nonwoven fabric can be suitably used for clothing textiles, medical patches, and the like.

  The filter unit which concerns on another one aspect | mode of this invention is equipped with the casing which has a pair of mesh-shaped opening which opposes, and the cotton-like body arrange | positioned in the said casing, The said cotton-like body is the said cotton-like body It is.

  The said filter unit uses the said cotton-like body. The fiber assembly used for the cotton-like body is mainly composed of fluororesin fibers that have high insulating properties and are easily charged with static electricity, so that static electricity is induced during the passage of gas, and the particle size is 100 nm due to the electrostatic force. The following fine particles can be captured. Therefore, since the fiber assembly can be made relatively wide with respect to the particle diameter for capturing the distance between the fibers, an increase in pressure loss can be suppressed. Further, since the cotton-like body is cotton-like, the surface area is large, and the passing gas meanders while colliding with the fibers, so that the fine particles can be effectively captured. Therefore, the filter unit can appropriately capture fine particles having a particle diameter of 100 nm or less by the cotton-like body disposed in the casing by allowing gas to pass between the pair of openings of the casing.

  The manufacturing method of the filter unit which concerns on another one aspect | mode of this invention comprises the process of obtaining a fiber assembly by crushing a fluororesin film, and the process of arrange | positioning the said fiber assembly in a casing.

  In the method for manufacturing the filter unit, a fluororesin fiber having a relatively long fiber length can be easily obtained by crushing the fluororesin film. Since the fiber aggregate composed of the fluororesin fibers can capture fine particles having a particle diameter of 100 nm or less by electrostatic force, the distance between the fibers can be made relatively wide. Therefore, the manufacturing method of the filter unit can easily and easily provide a filter unit that can capture fine particles having a particle diameter of 100 nm or less while suppressing an increase in pressure loss by disposing the fiber assembly in the casing. You can definitely get it.

  Here, the “fiber assembly” refers to a product obtained by weaving or knitting a plurality of fibers or a product obtained by interlacing or bonding fibers. The “main component” is a component having the largest content, for example, a component having a content of 50% by mass or more. Further, “fiber with an edge” means a fiber having a corner in a cross section perpendicular to the length direction of the fiber. “Nodule” means a node produced by overlapping when the fibrils constituting the fiber are intertwined. The “porosity” means the ratio of the area occupied by the voids in the cross section in the arbitrary direction of the porous body.

[Details of the embodiment of the present invention]
Hereinafter, the fiber assembly, the cotton-like body, the spinning, the felt, the nonwoven fabric, the filter unit, and the manufacturing method of the filter unit according to the embodiment of the present invention will be described in detail.

[Fiber assembly]
The fiber assembly according to an embodiment of the present invention shown in FIG. 1 is composed of a fluororesin fiber as a main component and a plurality of fluororesin fibers intertwined.

  Since the fiber assembly is mainly composed of fluororesin fibers, the strength of the fibers is relatively high. For this reason, since the diameter of a fluororesin fiber can be made comparatively small, the said fiber assembly can enlarge the surface area per unit volume.

  Examples of the material of the fluororesin fiber include polytetrafluoroethylene (PTFE), polyfluorinated vinylidene (PVDF), tetrafluoroethylene-perfluoroalkyl-vinyl ether copolymer (PFA), and the like. Of these, PTFE is preferable.

  The fluororesin fiber may include an edged fiber. Thus, by including the fiber with an edge in the said fluororesin fiber, since the surface area of fiber itself becomes large compared with the case where there is no edge, the microparticle capture | acquisition effect can be improved further. In addition, the said edge can be formed at the time of manufacture of a fluororesin fiber, for example.

  As the cross-sectional shape perpendicular to the length direction of the fiber with the edge, a shape having one or a plurality of protrusions on the outer periphery is preferable. In addition, the shape of the protrusion is preferably a triangular shape having an acute apex angle or a rectangular shape having a long side in the projecting direction. When the fiber with the edge has such a cross-sectional shape, the surface area per unit volume of the fiber assembly can be further increased.

  The fluororesin fiber may have a fine fiber structure including a nodule. By making the fluororesin fiber have a fine fiber structure including nodules in this way, it becomes easy to increase the porosity of the fiber assembly, so that the surface area per unit volume of the fiber assembly can be further increased. . Moreover, the path | route of the gas which passes the said fiber assembly can be complicated by a knot. By these, the fine particle capturing effect can be improved. In addition, the said nodule can be formed by extending | stretching a fluororesin film, for example. Specifically, resin fibers that are oriented in the direction of the stretching axis and island-shaped resins (called nodules) are formed by stretching.

  In particular, the fluororesin fiber may be a fiber (stretched PTFE fiber) obtained by crushing a stretched PTFE porous body as shown in FIG. The expanded PTFE fiber can reduce the fiber diameter. Further, the expanded PTFE fiber has an edge as shown in FIG. Furthermore, the expanded PTFE fiber has a knot in which fibrils constituting the fiber are intertwined in a complicated manner as shown in FIG. For this reason, the surface area per unit volume of the said fiber assembly can be further enlarged by making the said fluororesin fiber into an expanded PTFE fiber. PTFE has excellent chemical resistance and heat resistance. For this reason, the fiber aggregate excellent in weather resistance can be easily obtained by making the said fluororesin fiber into an expanded PTFE fiber. The stretching may be either uniaxial stretching or biaxial stretching.

  Moreover, you may use the fiber obtained by the well-known electrostatic spinning as said fluororesin fiber.

  As an upper limit of the average fiber diameter of the said fluororesin fiber, 40 micrometers is preferable, 20 micrometers is more preferable, and 10 micrometers is more preferable. When the average fiber diameter exceeds the upper limit, the porosity of the fiber assembly is relatively decreased with respect to the surface area of the fluororesin fiber, and thus pressure loss may increase. On the other hand, the lower limit of the average fiber diameter of the fluororesin fibers is not particularly limited, but is usually about 0.2 μm.

The lower limit of the specific surface area of the fluorine resin fibers, preferably from ^{1 m} 2 / g, more preferably ^{2m 2 / g, 5m 2 /} g is more preferred. There exists a possibility that a pressure loss may rise that the said specific surface area is less than the said minimum. On the other hand, the upper limit of the specific surface area of the fluororesin fiber is not particularly limited, but is usually about 15 m ² / g.

  As a minimum of average fiber length of the above-mentioned fluororesin fiber, 0.5 cm is preferred and 2 cm is more preferred. On the other hand, the upper limit of the average fiber length of the fluororesin fiber is preferably 300 cm, and more preferably 100 cm. If the average fiber length of the fluororesin fiber is less than the lower limit, it is necessary to closely entangle the fluororesin fiber to obtain the fiber assembly, and the porosity of the fiber assembly is likely to decrease. The pressure loss may not be reduced sufficiently. On the other hand, when the average fiber length of the said fluororesin fiber exceeds the said upper limit, there exists a possibility that the manufacturing cost of the said fluororesin fiber may rise. The “average fiber length of the fluororesin fibers” refers to the average length when the fluororesin fibers are linearly stretched.

As an upper limit of the density of the fiber assembly, 1.5 g / cm ³ is preferable, and 1.0 g / cm ³ is more preferable. When the density of the fiber assembly exceeds the above upper limit, the porosity of the fiber assembly is likely to decrease, and thus pressure loss may not be sufficiently reduced. On the other hand, the lower limit of the density of the fiber assembly is not particularly limited, but is usually about 0.5 g / cm ³ .

Porosity 90% by volume of the fiber assembly, the lower limit of the basis weight in the thickness 5mm terms, preferably ^{1000g / m 2, 1200g / m} 2 is more preferable. When the basis weight is less than the lower limit, the strength of the fiber assembly is insufficient, and when the fiber assembly is used, the fluororesin fibers are easily peeled off from the fiber assembly and the performance is improved. There is a risk of lowering with time. On the other hand, the upper limit of the basis weight is not particularly limited, but is usually 2000 g / m ² or less.

  The lower limit of the porosity of the fiber assembly is preferably 50%, more preferably 80%. On the other hand, the upper limit of the porosity of the fiber assembly is preferably 98% and more preferably 95%. If the porosity is less than the lower limit, the pressure loss may not be sufficiently reduced. On the other hand, when the porosity exceeds the upper limit, the amount of the fluororesin fiber is insufficient, and the surface area per unit volume may decrease.

The upper limit of the Gurley second of the fiber assembly is preferably 2 seconds, and more preferably 1 second. If the Gurley second of the fiber assembly exceeds the above upper limit, the pressure loss may not be sufficiently reduced. On the other hand, the lower limit of the Gurley seconds of the fiber assembly is not particularly limited, but is, for example, about 0.1 seconds. The “Gurley second” is measured in accordance with JIS-P8117 (2009), and means the time for 100 cm ³ of air to pass through a 6.45 cm ² sample with an average pressure difference of 1.22 kPa.

  The lower limit of the capture rate of particles having a particle diameter of 100 nm of the fiber aggregate is preferably 90%, more preferably 95%, and still more preferably 97%. There exists a possibility that the said fiber aggregate cannot be used as a filter as the particle | grain capture rate of the said fiber aggregate is less than the said minimum. On the other hand, the upper limit of the particle capture rate of the fiber assembly is not particularly defined and can be, for example, 99%.

  The fiber assembly may contain other fibers, additives, and the like, but it is preferable that the fiber assembly is substantially composed only of fluororesin fibers. Accordingly, the lower limit of the content of the fluororesin fiber in the fiber assembly is preferably 90% by mass, more preferably 95% by mass, and further preferably 99% by mass. Examples of the additive in the case of adding an additive to the fiber assembly include adsorbents such as activated carbon and silica gel, and catalysts such as titanium oxide and platinum that promote decomposition of organic substances.

[Cotton]
The cotton-like body according to one embodiment of the present invention is a cotton-like body using the fiber assembly. The said cotton-like body can be comprised by laminating | stacking the said fiber assembly irregularly.

  Since the cotton-like body uses the fiber assembly, the surface area per unit volume is large. Moreover, since the said fiber assembly has a fluororesin fiber as a main component, it is excellent in heat resistance. For this reason, the said cotton-like body can be used suitably as a heat-resistant sound-absorbing material and a heat-resistant heat insulating material.

  Moreover, since the said cotton-like body has a large surface area per unit volume, it is excellent in a constant temperature capability. In addition, since the fluororesin fiber is excellent in waterproofness, the cotton-like body has little moisture absorption and can be washed and steam sterilized. Furthermore, since an increase in pressure loss is suppressed, the cotton-like body is excellent in air permeability such as steam. For this reason, the said cotton-like body can be used suitably as a feather for bedding or clothing.

  Moreover, the fluororesin fiber has low toxicity to the human body, and the cotton-like body has a large surface area per unit volume. For this reason, the said cotton-like body can be used suitably as a medical filler. For example, in the regenerative treatment, the cotton-like body can be suitably promoted to regenerate in the self-tissue using the filled fluororesin fiber as a scaffold by filling the soft tissue or the bone defect part. The cotton-like body may be used for autologous tissue culture in an incubator. Furthermore, the said cotton-like body can also be used for regeneration of a tooth root. In addition, the cotton-like body can be compressed into a catheter, inserted into a cerebral aneurysm, and inflated by releasing, compressing and releasing into the aneurysm, and filling the aneurysm with fibers. It is preferable to fix a blood coagulant to the cotton fibers inserted into the cerebral aneurysm. This promotes blood clotting within the aneurysm.

  In addition, by adding a functional substance such as polylactic acid impregnated with a harmful substance decomposition catalyst such as a photocatalyst, a deodorizing fiber, a conductive fiber, or a therapeutic agent to the cotton-like body, other functions are added. You can also

〔spinning〕
The spinning according to one embodiment of the present invention is a spinning using the fiber assembly.

  As the fluororesin fiber of the fiber assembly used for spinning, an expanded PTFE fiber is preferable. By making the fluororesin fiber into expanded PTFE fiber, the spinning can be made into a yarn having flexibility and high strength.

  The spinning can be produced by a known production method, for example, a method of spinning the fiber assembly into a yarn. Further, in order to prevent fraying in the production of the spinning, the fiber assembly may be heated to a temperature equal to or higher than the melting point of the fluororesin fiber at the time of spinning or after spinning. The fraying can be prevented by mixing the fiber assembly with a resin having a melting point lower than that of the fluororesin and heating it to a temperature higher than the melting point of the low melting resin. When the fluororesin fibers are drawn PTFE fibers, examples of the low boiling point resin include fibers or particles such as FEP and PFA which are thermoplastic fluororesins that do not easily impair the characteristics of the fiber assembly.

  Since the spinning has a large surface area per unit volume of the fiber assembly, the waterproof property of the fluororesin fiber is easily developed. Therefore, the spun yarn can be suitably used as a sewing thread that requires waterproofness, a medical suture thread, a vascular ligation thread, and a spool filter.

  Further, since the spinning can be woven or knitted, it can be formed into a flat membrane or a tube, and therefore the spinning can be suitably used as a protective clothing and a medical patch that require waterproofness. The spinning can be used for the reconstruction of tubular organs such as artificial blood vessels. The spun yarn is spun, that is, has high strength because the fibers are close together, and can be sewn freely. For this reason, the spinning can be used for a branching organ having a complicated three-dimensional shape.

  In addition, by adding a functional substance such as polylactic acid impregnated with a harmful agent decomposition catalyst such as a photocatalyst, a deodorizing fiber, a conductive fiber, or a therapeutic agent to the spinning, other functions may be added. You can also.

〔felt〕
The felt according to one embodiment of the present invention is a felt using the fiber assembly.

  The felt can be manufactured by a known manufacturing method, for example, a method in which the fiber assembly is entangled using a punching needle or a water flow. Further, fraying can be prevented in the same manner as described in the above-described spinning production method.

  Since the felt uses the fiber assembly, the surface area per unit volume is large. Moreover, since the said fiber assembly has a fluororesin fiber as a main component, it is excellent in heat resistance and chemical resistance. For this reason, the felt can be suitably used as a filter or a sound absorbing material that requires heat resistance and chemical resistance.

  In addition, since the fiber assembly can relatively widen the distance between the fibers by reducing the fiber diameter, in addition to a large surface area per unit volume, it can suppress an increase in the pressure loss of the passing gas. it can. In addition, since the fluororesin fiber is excellent in waterproofness, the fiber assembly can be cleaned or sterilized by steam or boiling. For this reason, the felt can be suitably used as a wearable hepa filter such as a clean room hepa filter, a vacuum cleaner hepa filter, and a mask.

  Moreover, since the fluororesin fiber has low toxicity to the human body and a large surface area per unit volume, the felt can be suitably used as a medical filler. Further, the felt can be used for a stent utilizing its elasticity by being formed into a tube shape. Among them, use as an artificial cartilage such as a cushioning and flexible nose and ear, and use as an artificial cartilage at a tibia-femur contact portion of a knee joint are preferable. Since the felt has a large surface area per unit volume, it has porosity and is moderately impregnated with a lubricating joint fluid, so that it is easy to have both excellent cushioning properties and lubricity.

  Also, the felt formed into a tube shape can be used as a sealing material for piping utilizing elasticity and a cushioning sliding member utilizing the lubricity of fluororesin fibers. Since the felt has a large surface area per unit volume, the sealing material and the sliding member can be appropriately impregnated with oil to improve their functions.

  In addition, by adding a functional substance such as polylactic acid or the like impregnated with a harmful substance decomposition catalyst such as a photocatalyst, a deodorizing fiber, a conductive fiber, or a therapeutic agent to the felt, other functions may be added. You can also. Moreover, it can also be used as a filter that can selectively capture charged particles by charging the felt.

[Nonwoven fabric]
The nonwoven fabric which concerns on 1 aspect of this invention is a nonwoven fabric using the said fiber assembly.

  The nonwoven fabric can be produced by a known production method, for example, a method in which the fiber assembly is entangled with a punching needle, or a method in which the fiber assembly is dispersed in a solvent such as isopropanol, and is stretched into a sheet and dried. Furthermore, you may press the nonwoven fabric after manufacture with a heating roll etc., and may extend thinly. Further, fraying can be prevented in the same manner as described in the above-described spinning production method.

  Since the fiber assembly can relatively widen the distance between the fibers by reducing the fiber diameter, in addition to a large surface area per unit volume, an increase in pressure loss of the passing gas can be suppressed. For this reason, the said nonwoven fabric can be used suitably as a filter membrane.

  Moreover, since the surface area per unit volume of the said fiber assembly is large, the said nonwoven fabric is easy to express the waterproofness of a fluororesin fiber. Moreover, the fluororesin fiber is excellent in weather resistance. For this reason, the nonwoven fabric can be suitably used as a textile for clothing having water repellency, heat resistance, heat insulation and breathability. The nonwoven fabric is particularly suitable as a textile for medical protective clothing because it can be washed easily because it repels bodily fluids and can be sterilized.

  The nonwoven fabric can be used as an alternative to medical patches and organs because it is flexible, high-strength and easy to sew.

  In addition, by adding a functional substance such as polylactic acid impregnated with a non-woven material containing a decomposing substance such as a photocatalyst, a deodorizing fiber, a conductive fiber, or a therapeutic agent to the nonwoven fabric, other functions may be added. You can also. Moreover, it can also be used as a filter that can selectively capture charged particles by charging the nonwoven fabric.

[Filter unit]
The filter unit which concerns on another one aspect | mode of this invention is equipped with the casing 1 which has a pair of mesh-shaped opening 1a which opposes as shown in FIG. 4, and the cotton-like body 2 arrange | positioned in the said casing 1. . The cotton-like body 2 is a cotton-like body according to one embodiment of the present invention described above. The filter unit is attached to, for example, an exhaust port of various devices and functions as a filter.

  The filter unit can capture fine particles having a particle diameter of 100 nm or less by the cotton-like body 2 disposed in the casing 1 by allowing gas to pass between the pair of openings 1a of the casing 1. Moreover, since the said filter unit uses the cotton-like body 2, the raise of a pressure loss is suppressed.

<Casing>
The casing 1 has a cylindrical shape, and allows gas to pass through the opening 1a in the central axis direction. The cross-sectional shape of the casing 1 is selected according to the shape of the device to which the filter unit is attached. For example, one side or a diameter of 10 cm to 30 cm can be a square shape or a circular shape.

  The length of the casing 1 in the central axis direction is selected according to the shape of the device to which the filter unit is attached and the amount of the cotton-like body 2 disposed in the casing 1, and can be, for example, 0.5 cm to 10 cm. .

  The average thickness of the cylindrical peripheral wall of the casing 1 is not particularly limited as long as the strength of the casing 1 is ensured, and can be, for example, 1 mm or more and 10 mm or less.

  Although it does not specifically limit as a material of the casing 1, For example, metals, such as stainless steel and aluminum, and resin, such as a fluororesin, are mentioned.

(Opening)
The casing 1 has a pair of mesh-shaped openings 1a in the central axis direction. The pair of openings 1a are arranged to face each other with the internal space interposed therebetween. The pair of openings 1 a are preferably arranged perpendicular to the central axis of the casing 1. The length of the region sandwiched between the pair of openings 1 a (the distance between the pair of openings 1 a) is designed according to the size of the cotton-like body 2.

  The material of the non-opening portion of the opening 1 a can be the same as the material of the casing 1. The opening 1a can be entirely meshed or partly meshed. From the viewpoint of pressure loss and particulate capture efficiency, the opening 1a is entirely meshed. It is preferable to do.

  As a minimum of the nominal opening of the mesh part of opening 1a, 10 micrometers is preferred and 50 micrometers is more preferred. On the other hand, the upper limit of the nominal opening of the mesh portion is preferably 300 μm, and more preferably 100 μm. If the nominal mesh opening of the mesh portion is less than the lower limit, the pressure loss may not be sufficiently reduced. On the contrary, if the nominal opening of the mesh part exceeds the upper limit, the fibers constituting the cotton-like body 2 may flow out from the casing 1 to the outside.

  The lower limit of the average thickness in the central axis direction of the mesh portion of the opening 1a is preferably 0.5 mm, and more preferably 1 mm. On the other hand, the upper limit of the average thickness of the opening 1a is preferably 3 mm, and more preferably 2 mm. If the average thickness of the opening 1a is less than the lower limit, the strength of the opening 1a may be insufficient. Conversely, if the average thickness of the opening 1a exceeds the upper limit, the pressure loss may not be sufficiently reduced.

<Cotton>
The cotton-like body 2 is disposed in the casing 1. The arrangement amount of the cotton-like body 2 is determined so as to ensure sufficient capture efficiency of the target fine particles, and can be set to, for example, 0.03 kg or more and 3 kg or less.

[Production method of filter unit]
The manufacturing method of the filter unit which concerns on another one aspect | mode of this invention includes the fiber assembly acquisition process which obtains the fiber assembly 2 by crushing a fluororesin film, and the fiber assembly which arrange | positions this fiber assembly 2 in a casing A body disposing step.

  In the method for manufacturing the filter unit, a fluororesin fiber having a relatively long fiber length can be easily obtained by crushing the fluororesin film. Since the fiber assembly 2 composed of the fluororesin fibers can capture fine particles having a particle diameter of 100 nm or less by electrostatic force, the distance between the fibers can be made relatively wide. Therefore, the manufacturing method of the filter unit includes a filter unit that can capture fine particles having a particle diameter of 100 nm or less while suppressing an increase in pressure loss by disposing the fiber assembly 2 in the casing 1. It can be obtained easily and reliably.

<Fiber assembly acquisition process>
In the fiber assembly acquisition step, the fiber assembly 2 is obtained by crushing the fluororesin film as shown in FIG.

  Examples of the fluororesin film include various fluororesin films mainly composed of PTFE, PVDF, PFA and the like. Among these, the PTFE porous body stretched as described above is preferable.

  Although the said fluororesin film may be manufactured in order to obtain the fiber assembly 2, the unused part of the fluororesin film manufactured for the other purpose may be sufficient as it. Thus, by using the unused part of the fluororesin film manufactured for other purposes, the amount of the fluororesin film to be discarded can be reduced, and the manufacturing cost of the filter unit can be reduced.

  The method of crushing the fluororesin film is not particularly limited, and examples include a method of tearing by applying a mechanical tensile load, a method of shearing with a known rotary cutter mill, a method of crushing with a known ball mill, etc. Can do. When using a uniaxially stretched film as the fluororesin film, it is preferable to crush along the stretching direction. By crushing in the drawing direction in this way, a fluororesin fiber having a relatively long fiber length can be easily obtained.

  The crushing is preferably performed at a low temperature of 19 ° C. or lower and wet, and more preferably in liquid nitrogen. Since the substance has a property of becoming brittle when the temperature is lowered, the fluororesin film can be easily crushed by setting the temperature to 19 ° C. or lower. Further, by performing the pulverization in a wet manner, it is possible to suppress scattering of dust generated during the pulverization.

  A fiber assembly is obtained from the fluororesin fibers thus crushed.

<Fiber assembly arrangement process>
In the fiber assembly disposing step, the fiber assembly 2 is disposed in the casing 1. Specifically, at least one of the openings 1a of the casing 1 is opened, and the fiber assembly 2 is disposed in the casing 1 from the opening 1a. Moreover, the opening 1a is closed after the fiber assembly 2 is disposed.

  The fiber assembly 2 is preferably arranged as a cotton-like body. Thus, by making the said fiber assembly 2 into a cotton-like body, the raise of a pressure loss can further be suppressed. Although it does not specifically limit as a method of obtaining a cotton-like body from the said fiber assembly 2, For example, the method using a well-known cotton machine etc. can be mentioned.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  Although the said embodiment demonstrated the case where the said cotton-like body is arrange | positioned in a casing, the usage form of the said cotton-like body is not limited to this. For example, the cotton-like body can be directly disposed at an exhaust port of various devices.

  The fiber assembly of the present invention has a relatively large surface area per unit volume. Therefore, the fiber assembly of the present invention can be suitably used for a fine particle capturing filter and the like.

1 Casing 1a Opening 2 Cotton-like body (fiber assembly)

Claims (11)

  A fiber assembly mainly composed of fluororesin fibers.   The fiber assembly according to claim 1, wherein the fluororesin fiber includes an edged fiber.   The fiber assembly according to claim 1 or 2, wherein the fluororesin fiber has a fine fiber structure including a nodule.   The fiber assembly according to claim 1, wherein the fluororesin fiber is a fiber obtained by crushing a stretched polytetrafluoroethylene porous body.   The fiber assembly according to any one of claims 1 to 4, wherein the porosity is 80% by volume or more.   A cotton-like body using the fiber assembly according to claim 1.   Spinning using the fiber assembly according to claim 1.   A felt using the fiber assembly according to claim 1.   A nonwoven fabric using the fiber assembly according to claim 1. A casing having a pair of opposed mesh openings, and a cotton-like body disposed in the casing,
A filter unit, wherein the cotton-like body is the cotton-like body according to claim 6. Obtaining a fiber aggregate by crushing the fluororesin film;
And a step of arranging the fiber assembly in a casing.