Cylindrical filter

Abstract

To provide a cylindrical filter with excellent classifying performance, which can collect and remove coarse particles and allows microparticles to pass through.SOLUTION: A cylindrical filter, which is constituted of a plurality of non-woven clothes wound therearound, is excellent in classifying performance because the plurality of non-woven clothes have the same fiber materials. In particular, the plurality of non-woven clothes of the cylindrical filter according to the present invention are wound around so that cross sections in thickness directions of the adjacent non-woven clothes face each other. This enables the cylindrical filter to have excellent classifying performance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cylindrical filter configured by winding a plurality of non-woven fabrics.

Background Art

[0002] Slurry in which particles are dispersed has been used in various industrial applications in recent years. For example, in order to prepare a separator for an electrochemical device carrying particles capable of suppressing the generation of dendrites, or in order to prepare an electrode or a catalyst layer of an electrochemical device carrying active material particles, catalyst particles, or conductive particles, a slurry in which the particles are dispersed is applied to a fibrous structure such as a non-woven fabric or a film.

[0003] At this time, it is required that the slurry used does not contain particles having a large particle diameter. Since the slurry does not contain coarse particles, it is possible to provide a separator for an electrochemical device, an electrode, a catalyst layer, etc., in which only particles having a smaller particle diameter than the coarse particles are carried, and various performances such as thinning and high performance are improved.

[0004] From such a viewpoint, in order to remove particles having a large particle diameter from the slurry, the slurry is supplied to a cylindrical filter and filtered. As the cylindrical filter used at this time, for example, as disclosed in International Publication No. 2021 / 220720 (Patent Document 1), a cylindrical filter configured by winding a plurality of types of non-woven fabrics having different average fiber diameters is known. And the said cylindrical filter can collect and remove the particle | grains with a large particle diameter from a slurry, and can make the particle | grains with a small particle diameter pass (henceforth, it may be called classification performance together).

[0005] Incidentally, the applicant of the present application has proposed a cylindrical filter configured by winding a plurality of types of non-woven fabrics, specifically, the cylindrical filter disclosed in Japanese Patent Application Laid-Open No. 1-297113 (Patent Document 2). Patent Document 2 discloses the finding that by winding non-woven fabrics with a large average pore diameter and fiber diameter from the inside to the outside to form the cylindrical filter, a cylindrical filter with low liquid flow resistance and accurate filtration accuracy can be provided.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The applicant of the present application has studied a cylindrical filter according to the prior art as disclosed in Patent Documents 1 and 2. That is, the applicant has studied the classification performance of a cylindrical filter configured by winding a plurality of types of non-woven fabrics with different fiber materials such as average fiber diameter. In particular, based on the disclosure of Patent Document 2, the applicant has studied the classification performance of a cylindrical filter configured by winding non-woven fabrics with a large average pore diameter and fiber diameter from the inside to the outside.

[0008] In evaluating the classification performance exhibited by the cylindrical filter, reference was made to the disclosure of Japanese Patent Application Laid-Open No. 2015-97979, which also examines the classification performance of a cylindrical filter. Specifically, the evaluation method for the classification performance disclosed in paragraph number (0050) and FIG. 2 of the said patent publication was adopted. That is, from the disclosure of (0050) and FIG. 2, particles with a particle diameter of 50 μm to 70 μm were regarded as particles with a larger particle diameter (hereinafter sometimes referred to as coarse particles), and the collection performance of the said coarse particles was used as an index. Also, from the disclosure of (0050), particles with a particle diameter of 30 μm were regarded as particles with a smaller particle diameter (hereinafter sometimes referred to as fine particles), and the collection performance of the said fine particles was used as an index. Then, by confirming the collection rates of the coarse particles and fine particles used as these indices, the classification performance exhibited by the cylindrical filter was evaluated.

[0009] As a result of the evaluation, even when using a cylindrical filter according to the prior art, there were cases where particles with a particle diameter of 50 μm to 70 μm could not be completely collected. Therefore, even when a filtration object such as slurry was supplied to a cylindrical filter according to the prior art, there were cases where uncollected and leaked coarse particles remained in the filtered filtration object. Also, this problem occurred even in a cylindrical filter configured by winding a nonwoven fabric with a large average pore diameter and fiber diameter from the inside to the outside, as disclosed in Patent Document 2.

[0010] Therefore, the applicant of the present application prepared a cylindrical filter provided with a nonwoven fabric having a small average pore diameter and average fiber diameter so as to improve the collection performance of coarse particles exhibited by the said cylindrical filter. However, although the newly prepared cylindrical filter had improved collection performance of coarse particles, it unintentionally also improved the collection performance of fine particles and fine particles could not pass through.

[0011] An object of the present invention is to provide a cylindrical filter having excellent classification performance that can collect and remove coarse particles and allow fine particles to pass through.

Means for Solving the Problems

[0012] The present invention relates to “(Claim 1) A cylindrical filter formed by winding a plurality of nonwoven fabrics, wherein all of the nonwoven fabrics included in the cylindrical filter have the same fiber material. Cylindrical filter. (Claim 2) The cylindrical filter according to claim 1, wherein the plurality of nonwoven fabrics are wound in a state where cross-sections in the thickness direction adjacent to each other face each other. (Claim 3) The cylindrical filter according to claim 1 or claim 2, wherein all of the nonwoven fabrics included in the cylindrical filter have an average pore diameter of 50 μm or more.” is.

Advantages of the Invention

[0013] As a result of investigations by the applicant of the present application, surprisingly, in a cylindrical filter formed by winding a plurality of nonwoven fabrics, by having all of the plurality of nonwoven fabrics made of the same fiber material, it has been found that a cylindrical filter excellent in classification performance can be provided. In particular, the plurality of nonwoven fabrics included in the cylindrical filter according to the present invention are wound in a state where cross-sections in the thickness direction adjacent to each other face each other. By being a cylindrical filter having the configuration according to the present invention, a cylindrical filter having even better classification performance can be provided.

[0014] The reason for this has not been clearly clarified, but it is considered that this is because the following effects are exhibited. In a cylindrical filter according to the prior art, when particle collection progresses, the apertures of the nonwoven fabric are clogged by particles such as coarse particles, increasing the pressure loss of the cylindrical filter. As a result, the pressure of the object to be filtered, such as slurry, acting on the particles held in the apertures of the nonwoven fabric increases, causing the particles to be pushed out of the apertures and pass through the cylindrical filter, resulting in a decrease in classification performance. On the other hand, the cylindrical filter according to the present invention includes a portion where the cross-sections in the thickness direction of adjacent nonwoven fabrics face each other, and this portion is a portion where there is no nonwoven fabric and / or a portion where the nonwoven fabric is not continuous and is divided. Therefore, this portion is always easy for the object to be filtered to pass through, and the cylindrical filter according to the present invention having this portion has the characteristic that the pressure loss is difficult to increase. As a result, even when the collection of particles by the nonwoven fabric has progressed, the pressure of the object to be filtered acting on the particles held in the apertures of the nonwoven fabric is difficult to increase in the cylindrical filter according to the present invention, so that the particles held in the apertures of the nonwoven fabric are difficult to be pushed out from the apertures. Therefore, it is considered to be a cylindrical filter with excellent classification performance.

[0015] Also, by being a cylindrical filter having the configuration according to the present invention, even when the average pore diameters of a plurality of nonwoven fabrics are all 50 μm or more, and the object to be filtered has high permeability and the pressure loss can be reduced, but generally has a configuration that easily allows coarse particles (for example, particles having a particle diameter of 50 μm or more) to pass through, a cylindrical filter with excellent classification performance can be provided.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0017] In the present invention, various configurations can be appropriately selected, such as the following configurations. Note that, unless otherwise specified, all various measurements described in the present invention are performed under atmospheric pressure. Also, the measurements are performed under the temperature condition of 25°C. And, unless otherwise specified, all various measurement results described in the present invention are measured up to a value one digit smaller than the required value, and the required value is calculated by rounding the said value. As a specific example, when the required value is up to the first decimal place, the value up to the second decimal place is obtained by measurement, and the value up to the first decimal place is calculated by rounding the obtained value of the second decimal place, and this value is taken as the required value. And, each upper limit value and each lower limit value exemplified in the present invention can be arbitrarily combined.

[0018] Regarding the cylindrical filter according to the present invention, FIG. 1 which is a perspective view schematically showing the cylindrical filter according to the present invention, and FIG. 2(a) which is a schematic front view when seeing the belt-like laminate capable of constituting the cylindrical filter according to the present invention from the main surface on the non-woven fabric side, and FIG. 2(b) which is a schematic cross-sectional view showing a cross-section when the belt-like laminate shown in the schematic front view (a) is cut along a broken line, will be used for the explanation.

[0019] The cylindrical filter (100) according to the present invention includes a plurality of non-woven fabrics (10). And, in the present invention, the non-woven fabrics (10) included in the cylindrical filter (100) are all characterized by having the same fiber material. Here, "the non-woven fabrics included in the cylindrical filter all have the same fiber material" means that each non-woven fabric (10) included in the cylindrical filter (100) · the component of the constituent fibers, · the cross-sectional shape of the constituent fibers, · the average fiber diameter of the constituent fibers, · the fiber length of the constituent fibers (for example, whether the fibers have a continuous length or not, or whether they are short fibers having a specific fiber length or not), · the adhesion mode between the constituent fibers (for example, whether the constituent fibers are bonded by a binder or not), This means they are the same. Furthermore, it is desirable that the mass ratio of each constituent fiber contained in the nonwoven fabric is also the same so as to provide a cylindrical filter with excellent classification performance that can collect and remove coarse particles and allow fine particles to pass through.

[0020] A plurality of nonwoven fabrics (10) all having the same fiber material as described above can be obtained by cutting out a plurality of nonwoven fabrics (10) from a single nonwoven fabric as in the embodiments described later. In addition, when the manufacturing process of the nonwoven fabric is known, since they will have the same fiber material as described above, it is possible to determine that a plurality of nonwoven fabrics (10) cut out from a single nonwoven fabric all have the same fiber material.

[0021] As the constituent fibers of the nonwoven fabric (10), for example, inorganic fibers composed of inorganic components such as glass fibers, silica fibers, and alumina fibers, or organic fibers composed of resins can be adopted. The organic fibers are, for example, polyolefin resins (e.g., polyethylene, polypropylene, polyolefin resins with a structure in which a part of hydrocarbons is substituted with a halogen such as a cyano group, fluorine, or chlorine), polymethylpentene, styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polyester resin, etc.), polyimide resins, polyamideimide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having a nitrile group (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyether sulfone, etc.), fluorine resins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.), etc., and are fibers composed of known resins.

[0022] Note that the constituent components of the inorganic fibers and the constituent resins of the organic fibers may be composed of either linear polymers or branched polymers, and may also be block copolymers or random copolymers, and are not particularly limited regardless of the presence or absence of a three-dimensional structure or crystallinity. Furthermore, the organic fibers may be fibers formed by mixing a plurality of types of the resin, or composite fibers formed by compositing a plurality of types of the resin. Also, the inorganic fibers may be fibers formed by mixing a plurality of types of the inorganic components, or composite fibers formed by compositing a plurality of types of the inorganic components.

[0023] By being flexible, it is possible to prevent the nonwoven fabric (10) from being unintentionally deformed during winding, and in order to realize a cylindrical filter (100) having excellent classification performance, it is preferable that the nonwoven fabric (10) contains organic fibers as constituent fibers, and it is more preferable that the constituent fibers of the nonwoven fabric (10) are only organic fibers.

[0024] The constituent fibers of the nonwoven fabric (10) may be composed of one type of inorganic component or resin, or may be composed of a plurality of types of inorganic components or resins. As fibers composed of a plurality of types of inorganic components or resins, fibers generally called composite fibers, for example, core-sheath type, sea-island type, side-by-side type, orange type, bimetal type, etc. can be used.

[0025] Also, the constituent fibers of the nonwoven fabric (10) may include fibers having a cross-sectional shape other than fibers having a substantially circular cross-section or an elliptical cross-section. Note that as the profiled cross-section fibers, fibers having a cross-section such as a hollow shape, a polygonal shape such as a triangular shape, an alphabetic character type shape such as a Y shape, an irregular shape, a multi-leaf shape, a symbol type shape such as an asterisk shape, or a shape in which a plurality of these shapes are combined may be used.

[0026] The constituent fibers of the nonwoven fabric (10) can be obtained by known methods such as, for example, a melt spinning method, a dry spinning method, a wet spinning method, a direct spinning method (melt blowing method, spunbond method, electrospinning method, etc.), a method of extracting fibers having a fine fiber diameter by removing one or more resin components from composite fibers, a method of obtaining fibers by beating and splitting fibers.

[0027] The nonwoven fabric (10) can be prepared, for example, by a dry method of entangling fibers by feeding the above-described fibers to a carding device, an air-laying device, etc., a wet method of dispersing the fibers in a dispersion medium and forming a sheet to entangle the fibers, a direct spinning method (melt blowing method, spunbond method, electrospinning method, a method of spinning by discharging a spinning dope and a gas flow in parallel (for example, the method disclosed in JP-A-2009-287138)), etc., in which the fibers are spun and the spun fibers are entangled and collected.

[0028] And the constituent fibers of the nonwoven fabric (10) may be integrated. Examples of the method of integrating the constituent fibers include a method of entangling by a needle or a water stream, a method of fusing the constituent fibers by all-fusion-type fibers or partially-fusion-type composite fibers contained in the constituent fibers by subjecting them to heat treatment, a method of adhering the constituent fibers to each other using a binder, and the like.

[0029] The heat treatment method can be appropriately selected. For example, a method of heating or heating and pressing by a roll, a method of subjecting to a heating machine such as an oven dryer, an infrared heater, a dry heat dryer, a hot air dryer, etc. and heating, a method of irradiating infrared rays under no pressure to heat the contained fusion component, and the like can be used.

[0030] The average fiber diameter and fiber length of the fibers constituting the nonwoven fabric (10) can be appropriately adjusted. The average fiber diameter can be 0.1 to 70 μm, can be 1 to 50 μm, can be 5 to 30 μm, and can be 10 to 20 μm. In the present invention, the "fiber diameter" refers to the length in the direction orthogonal to the direction in which the fibers continuously extend in the fibers shown in the electron micrograph of the main surface of the nonwoven fabric, and the average value of the fiber diameters of 50 fibers to be measured is defined as the "average fiber diameter".

[0031] The constituent fibers may be short fibers cut to have a specific fiber length. The fiber length of the short fibers can be 5 to 120 mm, can be 10 to 100 mm, and can be 20 to 80 mm. Note that the "fiber length" of the short fibers cut to have a specific fiber length refers to the fiber length measured in accordance with JIS L1015 (2010), 8.4.1c direct method (method C). Alternatively, the constituent fibers can be fibers (fibers having a continuous length) that are not cut to have a specific fiber length and have a fiber length longer than 120 mm, such as directly spun fibers (melt blown fibers, electrospun fibers, etc.).

[0032] In particular, since there are few ends of the constituent fibers present in the nonwoven fabric (10), it is possible to prevent the presence of voids of an unintended size and realize a nonwoven fabric (10) having uniform voids. And by using the nonwoven fabric (10), it is possible to realize a cylindrical filter (100) having more intended classification performance. Therefore, the constituent fibers of the nonwoven fabric (10) are preferably fibers having a continuous length without a specific length. Note that fibers having a continuous length without a specific length can be prepared using a direct spinning method.

[0033] Further, a nonwoven fabric (10) may be formed by mixing fibers having a continuous length and fibers having a specific fiber length. Various configurations of the nonwoven fabric (10), such as basis weight and thickness, can be adjusted as appropriate. The basis weight can be 5 to 500 g / m 2 and can be 10 to 300 g / m 2 and can be 30 to 100 g / m 2 The thickness can be 0.1 to 50 mm, can be 0.3 to 10 mm, and can be 0.5 to 3 mm. Note that in the present invention, the basis weight refers to the mass per 1 m2 on the surface (main surface) having the largest area of the measurement object, and the thickness refers to the length between both main surfaces in the vertical direction when a load of 2.0 kPa is applied in the direction perpendicular to the main surface.

[0034] Further, in order to provide a cylindrical filter (100) with excellent classification performance, it is preferable to appropriately adjust the average pore size and the maximum pore size of the nonwoven fabric (10).

[0035] The average pore size can be 30 μm or more, 50 μm or more, 70 μm or more, or 100 μm or more. On the other hand, the upper limit value of the average pore size can be 220 μm or less, 200 μm or less, or 180 μm or less.

[0036] The applicant of the present application has found that, by virtue of the cylindrical filter (100) having the configuration according to the present invention, even in a case where the average pore sizes of a plurality of nonwoven fabrics (10) are all 50 μm or more, and the permeability of the object to be filtered is high and the pressure loss can be reduced, but the configuration generally allows coarse particles to pass through easily, it is possible to provide a cylindrical filter (100) with excellent classification performance. Therefore, in order to provide a cylindrical filter (100) with excellent classification performance and reduced pressure loss, the average pore size of the nonwoven fabric (10) can be 50 μm or more.

[0037] Also, the maximum pore size can be 50 μm or more, 100 μm or more, 150 μm or more, or 200 μm or more. On the other hand, the upper limit value of the maximum pore size can be 400 μm or less, 350 μm or less, or 300 μm or less.

[0038] The applicant of the present application has found that, by virtue of the cylindrical filter (100) having the configuration according to the present invention, even in a case where the maximum pore sizes of a plurality of nonwoven fabrics (10) are all 50 μm or more, and the permeability of the object to be filtered is high and the pressure loss can be reduced, but the configuration generally allows coarse particles to pass through easily, it is possible to provide a cylindrical filter (100) with excellent classification performance. Therefore, in order to provide a cylindrical filter (100) with excellent classification performance and reduced pressure loss, the maximum pore size of the nonwoven fabric (10) can be 50 μm or more.

[0039] The air permeability of the nonwoven fabric (10) can be adjusted as appropriate. The air permeability can be 50 cm / s or more, can be 100 cm / s or more, can be 150 cm / s or more, and can be 200 cm / s or more. On the other hand, the upper limit value can be adjusted as appropriate, but can be 600 cm / s or less and can be 500 cm / s or less. Note that the "air permeability" refers to the value measured in accordance with the Frazier method specified in JIS L1096. By using a nonwoven fabric (10) with a high air permeability, a nonwoven fabric (10) with a low liquid passing resistance can be realized, and a cylindrical filter (100) with a low pressure loss can be provided.

[0040] Each of the cylindrical filters (100) according to the present invention is configured by winding a plurality of nonwoven fabrics (10) having the same fiber material.

[0041] The mode of the cylindrical filter (100) is (Mode 1) A cylindrical filter (100) prepared by winding a plurality of nonwoven fabrics (10) trimmed to have a specific size, with the cross-sections in the thickness direction of each other facing each other and adjacent to each other, or (Mode 2) A cylindrical filter (100) formed by winding the next nonwoven fabric (10) on the outer periphery of a cylindrical nonwoven fabric prepared by winding the nonwoven fabric (10) (a cylindrical filter in which the nonwoven fabrics are wound concentrically). It can be. In particular, it is preferable that the cylindrical filter (100) is of Mode 1 so that a cylindrical filter (100) with excellent classification performance and reduced pressure loss can be provided.

[0042] The plurality of nonwoven fabrics (10) included in the cylindrical filter (100) according to the present invention are configured to be wound in a state where the cross-sections in the thickness direction of adjacent ones face each other. That is, the cylindrical filter (100) according to the present invention has a portion (14) where the cross-sections in the thickness direction of adjacent nonwoven fabrics (10) face each other.

[0043] By providing the configuration according to the present invention, a cylindrical filter (100) excellent in classification performance can be provided. Although the reason is not clear, it is considered that the following effects are exhibited.

[0044] In a conventional cylindrical filter, as particle collection progresses, the apertures of the nonwoven fabric are clogged by particles such as coarse particles, increasing the pressure loss of the cylindrical filter. As a result, the pressure of the object to be filtered, such as slurry, acting on the particles held in the apertures of the nonwoven fabric increases, causing the particles to be pushed out of the apertures, pass through the cylindrical filter, and reducing the classification performance.

[0045] On the other hand, the cylindrical filter (100) according to the present invention includes a portion (14) where the cross-sections in the thickness direction of adjacent nonwoven fabrics (10) face each other, and this portion (14) is a portion where the nonwoven fabric (10) does not exist and / or a portion where the nonwoven fabric (10) is not continuously present and the nonwoven fabric (10) is divided. Therefore, this portion (14) is always easy for the object to be filtered to pass through, and the cylindrical filter (100) according to the present invention provided with this has the characteristic that the pressure loss is difficult to increase.

[0046] As a result, even when particle collection by the nonwoven fabric (10) progresses, the cylindrical filter (100) according to the present invention is such that the pressure of the object to be filtered acting on the particles held in the apertures of the nonwoven fabric (10) is difficult to increase, so the particles held in the apertures of the nonwoven fabric (10) are difficult to be pushed out of the apertures. Therefore, it is considered to be a cylindrical filter (100) excellent in classification performance.

[0047] In the thickness direction of the cylindrical filter (100) (the direction parallel to the line segment connecting the center and the outer circumference with the shortest distance in the cross-section of the cylindrical filter, the left-right direction in FIG. 1), the nonwoven fabrics (10) may be laminated with their main surfaces directly in contact with each other, or a fabric such as a net (11) prepared separately may be interposed between the main surfaces of the nonwoven fabrics (10) for lamination. Due to the presence of the fabric, the nonwoven fabric is reinforced, thereby preventing the nonwoven fabric from being deformed unintentionally during fluid filtration. As a result, it is preferable that a cylindrical filter (100) with excellent classification performance can be provided.

[0048] The number of nonwoven fabrics (10) provided in the cylindrical filter (100) may be appropriately adjusted as long as it is two or more. It can be three or more, five or more, and seven or more.

[0049] The size of the cylinder of the cylindrical filter (100) can be appropriately adjusted according to the required application. When assuming that the cylindrical filter (100) is cut in a direction perpendicular to its length (c) direction (the up-down direction in FIG. 1), the outer diameter (a) in the cross-section can be 30 to 100 mm, 50 to 80 mm, or 60 to 70 mm.

[0050] Also, the inner diameter (b) in the cross-section can be 10 to 60 mm, 20 to 50 mm, or 25 to 40 mm.

[0051] And the length (c) of the cylindrical filter (100) can be 100 to 1000 mm, 150 to 800 mm, or 200 to 600 mm.

[0052] Next, a manufacturing method of the cylindrical filter (100) according to the present invention will be described with an example. Note that the description of the configurations already described will be omitted.

[0053] The manufacturing method of the cylindrical filter (100) according to the present invention can be appropriately selected. For example, (Step 1) Prepare a strip-shaped net (11) having a rectangular shape. (Step 2) Cut out a plurality of nonwoven fabrics (10) from a single nonwoven fabric. (Step 3) Prepare a strip-shaped laminate (13) by arranging the nonwoven fabrics (10) on the main surface of the strip-shaped net (11). (Step 4) Prepare a cylindrical support having pores (hereinafter sometimes referred to as a cylindrical support, not shown). (Step 5) Wind the strip-shaped laminate (13) around the cylindrical support from one short side to the other short side in the strip-shaped laminate (13). It can be a manufacturing method of a cylindrical filter (100) provided with a cylindrical support, comprising the above steps.

[0054] Describe Step 1.

[0055] The components constituting the strip-shaped net (11) can be appropriately adjusted, but it is preferably composed of the same components as the constituent fibers of the nonwoven fabric (10) so that lamination with the nonwoven fabric (10) is preferably performed. Specifically, when the constituent fibers of the nonwoven fabric (10) are organic fibers, the constituent fibers of the strip-shaped net (11) are also preferably organic fibers.

[0056] Various physical properties such as the thickness and mesh size of the strip-shaped net (11) can be appropriately adjusted. The thickness can be 0.1 to 3 mm, can be 0.3 to 2 mm, and can be 0.5 to 1 mm. Also, the vertical and horizontal lengths in the mesh can be 1 to 10 mm, can be 2 to 7 mm, and can be 3 to 5 mm.

[0057] And the length in the long side direction (the left-right direction on the paper surface in Fig. 2(b)) of the strip-shaped net (11) is appropriately adjusted so as to realize a cylindrical filter (100) having an outer diameter (a) to be obtained. Also, the length in the short side direction of the strip-shaped net (11) (the up-down direction on the paper surface in Fig. 2(b)) is appropriately adjusted so as to realize a cylindrical filter (100) having a length (c) to be obtained.

[0058] Describe (Process 2).

[0059] By cutting out a plurality of nonwoven fabrics (10) from a single nonwoven fabric, a plurality of nonwoven fabrics (10) all having the same fiber material can be obtained.

[0060] The shape of the cut nonwoven fabric (10) can be adjusted as appropriate, but in order to easily realize a cylindrical filter (100) having a required outer diameter (a) and length (c), it is preferably a rectangular shape of the same size for all. And the length in the long side direction of the cut nonwoven fabric (10) (the vertical direction on the paper surface in Fig. 2(b)) is adjusted as appropriate so as to realize a cylindrical filter (100) having the required length (c). Also, the length in the short side direction of the cut nonwoven fabric (10) (the left-right direction on the paper surface in Fig. 2(b)) is adjusted as appropriate so as to realize a cylindrical filter (100) having the required outer diameter (a).

[0061] Note that the plurality of nonwoven fabrics (10) may be flat or may have a corrugated shape. However, in order to realize a cylindrical filter (100) that prevents the occurrence of leakage and has excellent classification performance, the plurality of nonwoven fabrics (10) are preferably flat.

[0062] Describe (Process 3).

[0063] By arranging nonwoven fabrics (10) on the main surface of the strip net (11), a strip laminate (13) is prepared. At this time, the nonwoven fabrics (10) can be arranged such that the long side direction of the strip net (11) (the left - right direction on the paper surface in Fig. 2(b)) is parallel to the short side direction of the cut - out nonwoven fabrics (10) (the left - right direction on the paper surface in Fig. 2(b)). Further, it is preferable that the nonwoven fabrics are arranged with the cross - sections in the thickness directions of adjacent ones facing each other. In particular, it is preferable that the nonwoven fabrics (10) are arranged without having a portion where the nonwoven fabrics (10) are laminated with each other so as to realize a cylindrical filter (100) with excellent classification performance. In Figs. 1 and 2, a mode in which the cross - sections of adjacent nonwoven fabrics (10) are in contact with each other is illustrated. However, even when the adjacent nonwoven fabrics (10) are separated from each other, the cross - sections in their respective thickness directions may face each other.

[0064] The lamination method can be appropriately selected. The nonwoven fabrics (10) may be simply stacked on the main surface of the strip net (11), or may be laminated by bonding and integrating the strip net (11) and the nonwoven fabrics (10) by a binder or fiber adhesion.

[0065] The number of nonwoven fabrics (10) arranged on the main surface of the strip net (11) is two or more, and the number is appropriately adjusted so as to realize a cylindrical filter (100) having a required outer diameter (a).

[0066] The (process 4) will be described.

[0067] The cylindrical support (not shown) to be used has an opening (not shown) connecting the inner circumference and the outer circumference. The size, shape, number, and distribution pattern of the openings are appropriately adjusted so as to realize a cylindrical filter (100) having the required permeability for the object to be filtered.

[0068] The outer diameter of the cylindrical support to be used is appropriately adjusted so as to realize a cylindrical filter (100) having the required outer diameter (a) and inner diameter (b). Also, the inside of the cylindrical support to be used becomes the portion through which the object to be filtered passes when the cylindrical filter (100) provided with the cylindrical support is in use. Therefore, the inner diameter of the cylindrical support to be used is appropriately adjusted so as to realize a cylindrical filter (100) having the required permeability for the object to be filtered.

[0069] The length of the cylindrical support is appropriately adjusted so as to realize a cylindrical filter (100) having the required length (c). The length of the cylindrical support is preferably the same as the length in the short side direction (the vertical direction on the paper surface in Fig. 2(b)) of the belt-like laminate (13) so as to realize a cylindrical filter (100) having excellent classification performance due to less leakage.

[0070] The (step 5) will be described.

[0071] The method of winding the belt-like laminate (13) around the cylindrical support can be appropriately adjusted from one short side to the other short side of the belt-like laminate (13). For example, the belt-like laminate (13) can be wound around the cylindrical support such that the non-woven fabric side (the upper side on the paper surface in Fig. 2(a)) of the belt-like laminate (13) faces the cylindrical support. Note that the other short side of the belt-like laminate (13) can be fixed by adhesion or welding to the main surface of the belt-like laminate (13) wound around the cylindrical support.

[0072] As described above, a cylindrical filter (100) can be prepared in which a plurality of non-woven fabrics (10) are wound and configured, and all of the non-woven fabrics (10) provided in the cylindrical filter (100) have the same fiber material.

[0073] The cylindrical filter (100) prepared as described above may be used as it is, or end plates may be provided at both ends of the cylindrical filter (100), or another porous cylindrical support body that covers the outer peripheral surface of the cylindrical filter (100) may be provided, or a prefilter having a cylindrical shape may be provided on the outer peripheral surface or the inner peripheral surface of the cylindrical filter (100). The method of fixing the end plate or the cylindrical support body to the cylindrical filter (100) can be appropriately selected, and can be appropriately selected from general adhesion methods such as using a binder, double-sided tape, or adhesion by fusing constituent fibers or a hot melt web.

[0074] By passing a fluid to be filtered, such as a slurry, through the cylindrical filter (100), the fluid can be filtered. The method can be appropriately adjusted, but it can be filtered by passing from the outer part to the inner side (20) in the cylindrical filter (100) and passing through the thickness direction of the belt-like laminate (13). At this time, when the cylindrical filter (100) is provided with a cylindrical support body, the filtered fluid is discharged from the end through the space existing on the inner peripheral side of the cylindrical support body. Alternatively, it can be filtered by passing from the inner side (20) to the outer part in the cylindrical filter (100) and passing through the thickness direction of the belt-like laminate (13). At this time, when the cylindrical filter (100) is provided with a cylindrical support body, the fluid supplied from the end of the cylindrical support body is supplied to the inner side (20) in the cylindrical filter (100) through the space existing on the inner peripheral side of the cylindrical support body.

Example

[0075] Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

[0076] (Preparation of a cylindrical support body having pores) A cylindrical support body having pores with an outer diameter of 35.0 mm, an inner diameter of 25.4 mm, and a length of 244.0 mm was prepared. The cylindrical support body had a plurality of openings connecting the inner circumference and the outer circumference over the entire outer circumference.

[0077] (Preparation of a belt-like net) A polypropylene net (areal weight: 34 g / m 2 , thickness: 0.51 mm, apparent density: 0.067 g / cm 3 , mesh size: 3 mm × 4 mm) was prepared. Then, from the net, strip-shaped nets a (length in the long side direction: 300 cm, length in the short side direction: 262.5 mm), strip-shaped net b (length in the long side direction: 340 cm, length in the short side direction: 262.5 mm), and strip-shaped net c (length in the long side direction: 460 cm, length in the short side direction: 262.5 mm) were taken.

[0078] (Preparation of nonwoven fabric) The polypropylene resin was supplied to a meltblowing apparatus, and the molten polypropylene resin was spun and collected and allowed to cool to prepare a nonwoven fabric. At this time, by changing the spinning conditions and the spinning amount of the meltblowing apparatus, strip-shaped nonwoven fabrics a to i described in Table 1 were prepared.

[0079] Then, from each strip-shaped nonwoven fabric, a plurality of rectangular nonwoven fabrics (length in the short side direction: 260 mm, length in the long side direction: 40 cm) were cut out. At this time, a plurality of rectangular nonwoven fabrics were cut out from each strip-shaped nonwoven fabric so that the long side directions in each rectangular nonwoven fabric were parallel. In addition, the same alphabet as that given to the strip-shaped nonwoven fabric was given to the rectangular nonwoven fabric cut out therefrom. For example, a plurality of rectangular nonwoven fabrics cut out from strip-shaped nonwoven fabric a were all made into rectangular nonwoven fabric a.

[0080]

Table 1

[0081] (Example 1) On one main surface of strip-shaped net a, with the short side direction of the strip-shaped net and the short side direction of each cut nonwoven fabric being parallel, starting from one short side (the 1st side) of strip-shaped net a toward the other short side (the 7th side), as shown in FIG. 2, the rectangular nonwoven fabrics were arranged in the following order. 1st: Rectangular nonwoven fabric g Second: rectangular non-woven fabric g Third: rectangular non-woven fabric g Fourth: rectangular non-woven fabric g Fifth: rectangular non-woven fabric g Sixth: rectangular non-woven fabric g Seventh: rectangular non-woven fabric g At this time, the rectangular non-woven fabrics were arranged so as not to overlap each other, and the cross-sections in the thickness direction of adjacent ones were made to face each other in contact. Then, the long sides of the rectangular non-woven fabrics were aligned so as to be arranged in a straight line, and the rectangular non-woven fabrics were arranged on one main surface of the net so as not to protrude from the main surface of the net. In this way, a strip-shaped laminate having a length of 300 cm in the long side direction (where the length in the long side direction of the portion where the rectangular non-woven fabric and the strip-shaped net are laminated: 280 cm) was prepared. Then, starting from the short side on the side of the first rectangular non-woven fabric in the strip-shaped laminate toward the other short side, the strip-shaped laminate was wound around the cylindrical support. At this time, the non-woven fabric side in the strip-shaped laminate was made to face the cylindrical support. Also, the opening provided in the cylindrical support was covered with the non-woven fabric. Further, a heating plate was brought into contact with the portions protruding from both ends in the length direction (referred to as direction X) of the cylindrical support in the strip-shaped laminate wound around the cylindrical support. Then, by melting the said portion with the heating plate, the length in direction X in the strip-shaped laminate wound around the cylindrical support was made the same as the length of the cylindrical support. Furthermore, end plates having openings with the same size as the inner diameter of the cylindrical support at the central portions were provided at both ends in direction X of the cylindrical support and the strip-shaped laminate wound around the cylindrical support. As described above, a cylindrical filter provided with a cylindrical support, in which a plurality of non-woven fabrics are wound around the cylindrical support, was prepared. Note that all of the plurality of rectangular non-woven fabrics included in the cylindrical filter had the same fiber material.

[0082] (Example 2) A cylindrical filter with a cylindrical support, in which a plurality of non-woven fabrics are wound, was prepared in the same manner as in Example 1, except that the strength of winding the belt-like laminate around the cylindrical support was changed. Note that all of the plurality of rectangular non-woven fabrics included in the cylindrical filter had the same fiber material.

[0083] (Example 3) On one main surface of the belt-like net a, the rectangular non-woven fabrics were arranged in the following order as shown in FIG. 2, from one short side (the first) to the other short side (the seventh) of the belt-like net a so that the short side direction of the belt-like net was parallel to the short side direction of each non-woven fabric cut out in the short side direction of the belt-like net. First: Rectangular non-woven fabric h Second: Rectangular non-woven fabric h Third: Rectangular non-woven fabric h Fourth: Rectangular non-woven fabric h Fifth: Rectangular non-woven fabric h Sixth: Rectangular non-woven fabric h Seventh: Rectangular non-woven fabric h At this time, the rectangular non-woven fabrics were made not to overlap each other, and the cross-sections in the thickness direction of adjacent ones were made to face each other and be in contact. Then, the long sides of the rectangular non-woven fabrics were aligned so that they were arranged in a straight line, and the rectangular non-woven fabrics were arranged on one main surface of the net so that they did not protrude from the main surface of the net. In this way, a belt-like laminate having a length of 300 cm in the long side direction (where the length in the long side direction of the portion where the rectangular non-woven fabric and the belt-like net are laminated is 280 cm) was prepared. A cylindrical filter with a cylindrical support, in which a plurality of non-woven fabrics are wound, was prepared in the same manner as in Example 1, except that the belt-like laminate prepared in this way was used. Note that all of the plurality of rectangular non-woven fabrics included in the cylindrical filter had the same fiber material.

[0084] (Comparative Example 1) On one main surface of the strip net a, the short side direction of the strip net and the short side direction of each non-woven fabric cut out are made parallel, and from one short side (the 1st) of the strip net a to the other short side (the 7th), as shown in Fig. 2, rectangular non-woven fabrics are arranged in the following order. 1st: Rectangular non-woven fabric g 2nd: Rectangular non-woven fabric g 3rd: Rectangular non-woven fabric g 4th: Rectangular non-woven fabric h 5th: Rectangular non-woven fabric h 6th: Rectangular non-woven fabric i 7th: Rectangular non-woven fabric i At this time, the rectangular non-woven fabrics were arranged so as not to overlap each other, and the cross-sections in the thickness direction of adjacent ones were made to face each other and be in contact. Then, the long sides of the rectangular non-woven fabrics were aligned so as to be arranged in a straight line, and the rectangular non-woven fabrics were arranged on one main surface of the net so as not to protrude from the main surface of the net. In this way, a strip laminate having a length of 300 cm in the long side direction (where the length in the long side direction of the portion where the rectangular non-woven fabric and the strip net are laminated: 280 cm) was prepared. Except for using the strip laminate prepared in this way, in the same manner as in Example 1, a cylindrical filter provided with a cylindrical support in which a plurality of non-woven fabrics are wound was prepared. Note that the plurality of rectangular non-woven fabrics provided in the cylindrical filter did not all have the same fiber material.

[0085] (Comparative Example 2) On one main surface of the strip net b, the short side direction of the strip net and the short side direction of each non-woven fabric cut out are made parallel, and from one short side (the 1st) of the strip net b to the other short side (the 8th), as shown in Fig. 2, rectangular non-woven fabrics are arranged in the following order. 1st: Rectangular non-woven fabric e 2nd: Rectangular non-woven fabric e 3rd: Rectangular non-woven fabric f 4th: Rectangular non-woven fabric f 5th: Rectangular non-woven fabric g 6th: Rectangular non-woven fabric g 7th: Rectangular non-woven fabric h 8th: Rectangular non-woven fabric i At this time, the rectangular non-woven fabrics were arranged so as not to overlap each other, and the cross-sections in the thickness direction of adjacent ones were made to face each other and come into contact. Then, the long sides of the rectangular non-woven fabrics were aligned so as to be arranged in a straight line, and the rectangular non-woven fabrics were arranged on one main surface of the net so as not to protrude from the main surface of the net. In this way, a strip-shaped laminate with a length of 340 cm in the long side direction (among them, the length in the long side direction of the portion where the rectangular non-woven fabric and the strip-shaped net are laminated: 320 cm) was prepared. Except for using the strip-shaped laminate prepared in this way, in the same manner as in Example 1, a cylindrical filter provided with a cylindrical support body in which a plurality of non-woven fabrics are wound was prepared. Note that the plurality of rectangular non-woven fabrics included in the cylindrical filter did not all have the same fiber material.

[0086] (Comparative Example 3) On one main surface of the strip-shaped net c, the rectangular non-woven fabrics were arranged in the following order as shown in FIG. 2 from one short side (the 1st) to the other short side (the 11th) of the strip-shaped net c so that the short side direction of the strip-shaped net and the short side direction of each non-woven fabric cut out were parallel. 1st: Rectangular non-woven fabric a 2nd: Rectangular non-woven fabric b 3rd: Rectangular non-woven fabric c 4th: Rectangular non-woven fabric d 5th: Rectangular non-woven fabric e 6th: Rectangular non-woven fabric g 7th: Rectangular non-woven fabric g 8th: Rectangular non-woven fabric h 9th: Rectangular non-woven fabric h 10th: Rectangular non-woven fabric i 11th: Rectangular non-woven fabric i At this time, the non-woven fabrics of the rectangles were arranged so as not to overlap each other, and the cross-sections in the thickness direction of the adjacent non-woven fabrics were made to face each other and be in contact. Then, the long sides of the non-woven fabrics of the rectangles were aligned so as to be arranged in a straight line, and the non-woven fabrics of the rectangles were arranged on one main surface of the net so as not to protrude from the main surface of the net. In this way, a strip-shaped laminate having a length of 460 cm in the long side direction (where the length in the long side direction of the portion where the rectangular non-woven fabric and the strip-shaped net are laminated: 440 cm) was prepared. A cylindrical filter provided with a cylindrical support body in which a plurality of non-woven fabrics are wound was prepared in the same manner as in Example 1, except that the strip-shaped laminate prepared in this way was used. Note that the plurality of rectangular non-woven fabrics provided in the cylindrical filter did not all have the same fiber material.

[0087] The physical properties of the cylindrical filters prepared in the examples and comparative examples are summarized in Table 2. The following methods were used for the measurement of the physical properties.

[0088] (Measurement method of air permeability resistance) Air was supplied to the air inlet of a manometer (manufactured by Cosmo Instruments Co., Ltd., model: DM-3500B) at a flow rate of 52 L / min. At this time, the generated air permeability resistance was measured, and the blank value T (unit: mmAq) was obtained. Next, for the cylindrical filters provided with the cylindrical support bodies prepared in the examples and comparative examples, the end plate provided at one end in the direction X was closed with a plate, and the opening of the end plate provided at the other end was connected to the air inlet of the manometer. Then, air was supplied at a flow rate of 52 L / min from the outer peripheral side where the strip-shaped laminate in the cylindrical filter was exposed. As a result, the supplied air moves from the outer peripheral side of the exposed strip-shaped laminate in the cylindrical filter provided with the cylindrical support body in the thickness direction of the strip-shaped laminate, passes through the space existing on the inner peripheral side of the cylindrical support body, and is supplied from the opening of the end plate provided at the other end to the air inlet of the manometer. At this time, the ventilation resistance generated when air passes through a cylindrical filter equipped with a cylindrical support was measured, and the measured value R (unit: mmAq) was obtained. The value obtained by subtracting the blank value T (unit: mmAq) from the measured value R (unit: mmAq) thus obtained was taken as the ventilation resistance (unit: mmAq) of the cylindrical filter equipped with a cylindrical support.

[0089] (Measurement method of collection rate) Seven types of test powders (Kanto loam) defined in JIS Z8901:2006 "Test Powders and Test Particles" were prepared. Next, the seven types of test powders (Kanto loam) were mixed with water so that their mass concentration became 40 ppm to prepare a test solution (A). Then, the test solution (A) was filtered through the cylindrical filter by passing the test solution (A) at a rate of 20 liters / minute from the outer peripheral side where the strip-shaped laminate in the cylindrical filter was exposed to the space existing on the inner peripheral side of the cylindrical support. After that, the filtered test solution (B) was collected when 50 liters of the test solution (A) had passed through the cylindrical filter. The particle size (unit: μm) and the number (unit: pieces) of the particles contained in the test solution (A) and the particles contained in the collected test solution (B) were measured using a particle counter (multisizer4 manufactured by beckman). Then, by substituting the obtained measurement results into the following formula, the collection rate (unit: %) of the particles exhibited by the cylindrical filter for each particle size from 14 μm to 70 μm was calculated. In the formula, x means the particle size to be calculated and is any number from 14 to 70. Collection rate (%) = 100 × ("Number of particles with particle size x μm contained in test solution (A)" - "Number of particles with particle size x μm contained in test solution (B)") / "Number of particles with particle size x μm contained in test solution (A)"

[0090]

Table 2

[0091] The cylindrical filters prepared in the examples and comparative examples are composed of non-woven fabrics (and strip-shaped nets) with an average pore diameter of 50 μm or more. Therefore, it is considered that at least particles with a particle diameter of 50 μm or more will leak from the cylindrical filters prepared in the examples and comparative examples. However, the cylindrical filters prepared in the examples, which are composed of multiple non-woven fabrics having the same fiber material, did not show leakage of particles with a particle diameter of 50 μm to 70 μm. And it was able to pass particles with a particle diameter of 30 μm and 29 μm or less (the collection rate of particles with a particle diameter of 30 μm or less was less than 100%).

[0092] On the other hand, the cylindrical filter prepared in Comparative Example 1 showed leakage of particles with a particle diameter of 50 μm to 70 μm. Notably, although Comparative Example 1 is provided with a non-woven fabric (non-woven fabric g) having a smaller average pore diameter and a non-woven fabric (non-woven fabric i) having a smaller maximum pore diameter than Example 3 (non-woven fabric h), leakage of particles with a particle diameter of 50 μm to 70 μm was observed.

[0093] Also, the cylindrical filters prepared in Comparative Examples 2 to 3, which are provided with non-woven fabrics (non-woven fabrics e and f, or non-woven fabrics a to d) having a smaller average pore diameter, maximum pore diameter, and average fiber diameter than Comparative Example 1, did not show leakage of particles with a particle diameter of 50 μm to 70 μm. However, the collection rate of particles with a particle diameter of 30 μm and 29 μm or less was 100% and they could not pass through.

[0094] From the results of comparing the examples and comparative examples, it was found that the cylindrical filter according to the present invention, which is composed of multiple non-woven fabrics having the same fiber material, has excellent classification performance.

Industrial Applicability

[0095] The present invention can be used as a cylindrical filter for filtering objects to be filtered such as slurries, for example.

Explanation of Signs

[0096] 100: Cylindrical filter 10: Non-woven fabric 11: Cloth (striped net) 20: Inner side in the thickness direction of the cylindrical filter a: Outer diameter of the cylindrical support b: Inner diameter of the cylindrical support c: Length of the cylindrical support 13: Striped laminate 14: Portion where the cross-sections in the thickness directions of adjacent non-woven fabrics face each other

Claims

1. A cylindrical filter formed by winding a plurality of non-woven fabrics, wherein all of the non-woven fabrics included in the cylindrical filter have the same fiber material, the cylindrical filter.

2. The cylindrical filter according to claim 1, wherein the plurality of non-woven fabrics are wound in a state where cross-sections in the thickness directions of adjacent ones face each other.

3. The cylindrical filter according to claim 1 or claim 2, wherein all of the non-woven fabrics included in the cylindrical filter have an average pore diameter of 50 μm or more.

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