JP4800643B2 - Cylindrical filter and manufacturing method thereof - Google Patents

Description

  The present invention is a cylindrical filter used to filter a fluid, mainly filtering water, oil, paint, surfactant, food and other liquids, dust such as metal powder in compressed air, oil droplets, The present invention relates to a cylindrical tube filter used for removing moisture and mist, and filtering a gas such as an automobile air element, and a method for manufacturing the same. More specifically, the present invention relates to a cylindrical filter having a long filtration life, a high pressure resistance, and a high filtration accuracy, and a method for manufacturing the same.

  A cylindrical type filter using fibers as a constituent component of the filtration layer is usually formed by forming a filtration layer made of fibers into a hollow cylindrical shape, and the target filtration object is from the outermost peripheral part of the hollow cylinder to the central part. And is used for filtering and is particularly useful for liquid filtration.

  The cylindrical filter has a structure in which the filtration layer captures fine particles in the liquid while the liquid passes through the filtration layer. This cylindrical filter is widely used in various industries such as filtration of purified water in the pharmaceutical industry, electronics industry, etc., liquid filtration in the drinking water production process in the food industry, and filtration of coating agents in the automobile industry. Yes.

  Conventionally, as a cylindrical filter used in the above fields, for example, as described in Patent Document 1 and Patent Document 2, the former is a staple fiber card, and the latter is a spunbond nonwoven fabric manufacturing method. A tubular filter is disclosed in which a web of a heat-adhesive conjugate fiber is formed by fibering, the web is wound under heating, and heat-bonded with a low melting point component of the conjugate fiber to be bonded and integrated. Since these cylindrical filters use heat-adhesive conjugate fibers, peeling between the heat-bonded fibers hardly occurs even when the filtration pressure is increased, so that there is an advantage that stable filtration accuracy can be obtained.

  Further, Patent Document 3 discloses a cylinder formed by heat-treating an ultrafine composite fiber web obtained by changing the fiber diameter while performing melt blow spinning and winding it around a core, and then pulling out the core. A mold filter is disclosed. Furthermore, Patent Document 4 discloses a cylindrical filter in which several types of melt-blown nonwoven fabrics having different fiber diameters and apparent densities are rolled back so that the average fiber diameter and the average pore diameter become larger toward the outer side of the porous core cylinder. It is disclosed. In general, a cylindrical filter using a melt blown nonwoven fabric as a filtration layer has advantages that the filtration accuracy is good and the manufacturing process is simplified.

Furthermore, Patent Document 5 discloses a sheet (for example, filter paper, membrane filter) having a desired hole diameter after heating a fiber assembly layer containing a heat-fusible conjugate fiber to a temperature for heat-sealing, winding it around a core. Etc.) are wound together with the fiber assembly layer to form a microfiltration layer, and then only the fiber assembly layer is wound up to form a prefiltration layer, and after cooling, the winding core is pulled out to produce a cylindrical filter for microfiltration. A method is disclosed.
Japanese Patent Laid-Open No. 52-152575 JP-A-8-222604 JP-A-5-96110 JP-A-1-297113 Japanese Patent Publication No.56-49605

  However, the above conventional techniques have the following problems. In addition, in order to simplify description, in the following description, it demonstrates focusing on liquid filtration. In Patent Document 1, since the constituent fibers (staple fibers) are firmly heat-bonded to each other, there is a deformation resistance against a high filtration pressure, but the void diameter distribution range formed between the fibers is narrow. There was a problem that clogging was quick and the filtration life was relatively short. The fiber made by the spunbond nonwoven fabric manufacturing method as in Patent Document 2 is a web or nonwoven fabric that is not heat stretched and has no waist, and is thinner than the staple fiber nonwoven fabric described above when thermally bonded. The cylindrical filter that is made of a high non-woven fabric and wound around it has fine collection of fine particles and has good collection accuracy, but the tendency of surface filtration to filter on the surface of the cylindrical filter is further increased, Since the area is small, there is a serious problem as a filter that clogging is quicker and the filter life is relatively short.

  Moreover, in patent document 3 and patent document 4, since the melt blown nonwoven fabric to be used can be comprised by the ultrafine fiber of 1 dtex or less, the space | gap between fibers becomes small and is used widely as a filter material, On the other hand, filtration There was a problem that the flow rate was small and clogging was likely to occur, and the filtration life was shortened.

  Further, in Patent Document 5, a microfiltration layer having the same width is interposed in the heat-bonding fiber assembly layer, and in use, the heat-bonding fiber assembly layer, which is the pre-filtration layer, is directed to the microfiltration layer. In the pre-filtration layer, the distribution range of the void diameter formed by the heat-sealing fiber is narrow, and the microfiltration layer exists in a state of being strongly pressed in the heat-sealing fiber layer. Since the surface filtration of the material is strong and the filtration area is not large like a pleated fold filter, there is a problem that clogging by filtration is relatively fast and the filtration life is short.

  When a non-woven fabric is simply rolled up on a paper tube, when the winding diameter is small, the tension is stronger than when it is large, and the non-woven fabric wound around the center of the paper tube is thinner than the non-woven fabric wound around the outer circumference ) The cylindrical filter, which is a heat-bonded composite fiber or web made of heat-adhesive composite fibers, which is generally bonded by heat bonding using a phenomenon, is a fiber that gradually becomes closer to the center. Since the fiber density gradient which increases the density is attached and the central inner cylindrical part is wound in a state where the fiber density is higher than that of the outer peripheral part, the cylindrical filter is generally considered to be a deep-layer filtration material having a long filtration life. However, even if a cylindrical filter is made by simply winding a web or non-woven fabric made of heat-adhesive conjugate fibers and thermally bonding them, the fiber density gradient is not sufficient, and surface filtration that filters on the surface of the cylindrical filter The phenomenon was dominant, and the problem of fast clogging by collected particles and short filtration life was always present.

  In addition, a pleated filter with a pleat-folded flat fiber aggregate such as a nonwoven fabric that has an extremely expanded filtration surface area has good filtration accuracy and has a long filtration life. The depth filtration filter represented by a mold-type cylindrical filter in which the fibers are thermally bonded while winding the aggregate into a cylindrical shape is inferior in filtration accuracy compared to the pleated filter regardless of the fiber density gradient. When trying to improve the filtration life, there is a problem that the filtration life is extremely reduced, and it is extremely difficult to achieve both filtration accuracy and filtration life in the mold type filter. Accordingly, the fact is that a cylindrical filter having a long filtration life, a high pressure strength, and a high filtration accuracy has not been obtained.

  The present inventors, on one side of the filtration nonwoven fabric layer, heat-treating the entangled nonwoven fabric in which the heat-shrinkable layer made of heat-shrinkable fibers is integrated to heat-shrink the heat-shrinkable fibers to form a kind of pleated filter nonwoven fabric layer. A multi-layered depth filtration filter with the characteristics of a pleated fold filter while being a mold-type filter by forming a multi-layered nonwoven fabric having a large number of ridges and winding it into a cylindrical filter The above problem was solved. That is, the first cylindrical filter of the present invention is a cylindrical filter including a cylindrical body in which a multilayer nonwoven fabric composed of a plurality of fiber layers is wound, and adjacent multilayer nonwoven fabrics are thermally bonded. The multilayer nonwoven fabric includes a heat-shrinkable fiber layer containing a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C and a main fiber layer containing a main fiber having a heat-shrinkage rate of 140% or less at 4%, And the fiber layer which comprises at least one surface of a multilayer nonwoven fabric contains the heat bondable fiber containing a heat bonding resin component, and the difference of each heat shrink rate in the heat bonding temperature of the said heat shrink fiber and a main fiber is 5% It is the above.

  The second tubular filter of the present invention is a tubular filter comprising a tubular body in which a multilayer nonwoven fabric composed of a plurality of fiber layers is wound, and adjacent multilayer nonwoven fabrics are thermally bonded to each other, The multilayer nonwoven fabric includes a heat-shrinkable fiber layer including a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer including a main fiber having a heat-shrinkage rate of 140% or less at 4%. The fiber layer constituting at least one surface of the layered nonwoven fabric includes heat-adhesive fibers containing a heat-adhesive resin component, and the multilayer nonwoven fabric is a multi-layered nonwoven fabric that forms a number of ridges by heat shrinkage. Features.

  The manufacturing method of the cylindrical filter of the present invention is a manufacturing method of a cylindrical filter including a cylindrical body in which a multilayer nonwoven fabric composed of a plurality of fiber layers is wound, and adjacent multilayer nonwoven fabrics are thermally bonded. The multilayer nonwoven fabric includes a heat-shrinkable fiber layer containing a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer containing a main fiber having a heat shrinkage rate of 140% or less at 140 ° C. And the fiber layer which comprises at least one surface of a multilayer nonwoven fabric contains the heat-adhesive fiber containing a heat-bonding resin component, and the difference of each heat contraction rate in the heat-bonding temperature of a heat-shrink fiber and a main fiber is 5 %, And the multilayer nonwoven fabric is heated to a temperature lower than the melting point of the heat-adhesive resin component of the heat-adhesive fiber by 5 ° C. or more to shrink the heat-shrinkable fiber layer to form a large number of wrinkles. Forming a multi-layered nonwoven fabric, said multi-layered nonwoven fabric A cylindrical shape in which the multilayer nonwoven fabric is wound by winding the core from the multilayer nonwoven fabric wound around the core while being heated and bonded at the thermal bonding temperature of the thermal adhesive fiber. It is characterized by forming a body.

  The cylindrical filter of the present invention has a main filtration layer mainly composed of filtration of a multi-layered nonwoven fabric into a pleat shape, and has the same form as a filter in which pleated folded filters having a long filtration life are laminated in multiple stages. Therefore, the filtration accuracy is higher and the filtration life is longer than the conventional mold-type cylindrical filter. In particular, the tubular filter of the present invention has a filtration area larger than that of a conventional mold-type tubular filter, in which a non-woven fabric layer with high filtration accuracy is wound in the middle of winding to increase filtration accuracy, and the filtration accuracy is increased. Overwhelmingly large and long filtration life.

  In addition, according to the cylindrical filter of the present invention, according to the hydroentanglement process, the fiber treatment agent can be washed and removed by the hydroentanglement process, so that the fiber treatment agent remains very little, and the residual amount is set to 0. A cylindrical filter having a very low (elution) impurity content of 05% by mass or less can be obtained. For this reason, since there is little foaming at the time of use, the cylindrical filter of this invention is suitable for filtration of the washing | cleaning liquid of electronic device members, such as a foodstuff, a pharmaceutical, and a semiconductor which dislike (elution) impurities.

  According to the method for producing a cylindrical filter of the present invention, at least two kinds of fiber layers, ie, a heat shrinkable fiber layer having a heat shrinkage difference of 5% or more at a heat bonding temperature and a main fiber layer mainly composed of filtration, are laminated. A plurality of pleated ridges extending in the width direction of the nonwoven fabric by heat-shrinking the heat-shrinkable fiber layer in a separate process before winding the wound multilayer nonwoven fabric or in a preheating process when winding A multi-layered nonwoven fabric having an object can be obtained. The multi-layered nonwoven fabric is a bulky nonwoven fabric with apparently low fiber density, and when this is wound around a core, a cylindrical filter having a high fiber density in the vicinity of the core and a low fiber density at the outer periphery can be easily obtained. be able to.

  As a result of intensive studies, the inventors of the present invention heat-treated a heat-shrinkable fiber by heat-treating a multilayer nonwoven fabric composed of a plurality of fiber layers including a main fiber layer mainly having a filtration function and a heat-shrinkable fiber layer containing heat-shrinkable fibers. By making the filter layer into a multi-layered nonwoven fabric having a large number of ridges in the form of a pleated shape, and further winding this, a cartridge filter in which a type of pleated folding filter is multilayered However, the problem was solved by using a multilayer type depth filtration filter having the characteristics of a pleated folding filter while being a mold type filter.

  In particular, the main fiber layer mainly having a filtration function increases the filtration life when the filtration area is increased, and the inner fiber portion of the cylindrical filter is wound by compressing and winding the nonwoven fabric from the outer peripheral portion. Since the fiber gap is small, that is, the fiber gap is small, a nonwoven fabric (main filtration layer) having a slightly larger fiber diameter or lower fiber density than the nonwoven fabric used for the pleated fold filter that blocks the particle diameter to be blocked, A fiber layer obtained by laminating a nonwoven fabric (fluid layer) made of fibers having a fiber diameter larger than that of the main filtration layer that requires a liquid permeation function, wherein a heat shrink fiber layer is laminated on one side of the main fiber layer. When the layered nonwoven fabric is heated to shrink to form a multi-layered nonwoven fabric, and the cylindrical filter wound around the core, the multilayered nonwoven fabric in the vicinity of the core is pushed under strong tension. Busa is, fiber gap in a state of considerably smaller than when the non-woven fabric. As a result, even if the multilayer nonwoven fabric is a nonwoven fabric having a slightly larger fiber diameter or smaller fiber density than the nonwoven fabric in the pleated fold filter, it becomes a nonwoven fabric with a fiber gap corresponding to these so that finer particles can be collected. become.

  Moreover, since a multi-layered nonwoven fabric having a bulky appearance is wound, a sufficient fiber density gradient can be obtained, so that the cylindrical filter is a depth filtration. And since the main fiber layer consisting of the main filtration layer sandwiched between the multi-layered fluid-permeable layers is a kind of pleated fold filter, it exhibits a state of pleated fold filter multistage filtration in which the fiber density gradually increases, Compared with the conventional mold type filter, it has a finer main filtration layer, so that the filtration accuracy is remarkably high and the filtration life is long.

  Specifically, the cylindrical filter of the present invention has a heat-shrinkable fiber layer containing a heat-shrinkable fiber having a heat-shrinkage rate of 9% or more at 140 ° C, and preferably has a heat-shrinkage rate of 4% at 140 ° C on at least one surface thereof. A laminated web in which a main fiber layer containing the following main fibers is laminated (preferably a laminated web in which fibers are entangled and integrated), and the heat shrinkage difference between the heat shrinkable fibers and the main fibers is 5% at the heat bonding temperature. A multi-layer nonwoven fabric having at least one fiber layer in which at least one of the fiber layers is a heat-adhesive fiber containing a heat-adhesive resin component (preferably, a low-melting point thermoplastic resin that is a heat-adhesive resin component and a fiber-based component) A high-melting thermoplastic resin having a melting point difference of 10 ° C. or more, and a multilayer nonwoven fabric (preferably a water stream) having at least one surface formed of a fiber layer containing the thermo-adhesive fiber Confounding processing The multilayer nonwoven fabric integrated by which fiber entanglement) is heated to a temperature lower than the melting point of the heat-adhesive resin component of the heat-adhesive fiber by 5 ° C. or more to heat-shrink the heat-shrinkable fiber layer, and the width of the nonwoven fabric A bulky non-woven fabric that forms a large number of pleated ridges extending in the direction. Subsequently, the melting point of the heat-bonding resin component of the heat-bonding fiber constituting the multi-layered nonwoven fabric is equal to or higher than the melting point of the heat-bonding resin component (low-melting point thermoplastic resin in the case of a heat-bonding conjugate fiber), and the high-melting point thermoplasticity. The resin is melted at a melting point of less than −10 ° C.), and at least the non-woven fabric is thermally bonded and integrated with at least the thermo-adhesive resin component, so that the filter outer periphery has a lower fiber density than the inside of the filter and depth filtration is possible. In addition, it is possible to obtain a cylindrical filter that can perform filtration similar to multi-stage microfiltration with a pleated filter layer of multiple ridges.

  The multilayer nonwoven fabric used in the present invention is composed of a main fiber layer for the purpose of filtration and a heat-shrinkable fiber layer for increasing the number of main fiber layers. The fiber layers are preferably integrated by a fiber entanglement technique such as hydroentanglement or needle punching. Of course, when the main fiber layer is multi-layered, it is not inconvenient even if these are integrated by other means such as heat bonding. Since the main purpose is to use in a filter, the hydroentanglement process in which the fiber entanglement method is entangled by a water stream is a fiber treatment agent adhering to the fiber surface or an oligomer generated from a constituent thermoplastic resin. It is most preferable because impurities can be removed at the same time.

  The difference in thermal shrinkage ratio between the heat shrinkable fiber and the main fiber at the heat bonding temperature is 5% or more, preferably 20% or more, more preferably 30% or more. Here, the “thermal bonding temperature” means that the difference in thermal shrinkage is 5% or more in the range from the melting point of the thermal bonding resin component to −5 ° C. to the melting point of the resin with the highest melting point of the main fiber to −10 ° C. The temperature is arbitrarily selected. If the difference in thermal shrinkage is less than 5%, it may be difficult to increase the number of layers even when the multilayer nonwoven fabric is contracted. In general, since shrinkage processing is performed at around 140 ° C., the thermal shrinkage rate of the fiber used assuming shrinkage processing is defined by a value measured at 140 ° C. In this case, if the difference 5% in the heat shrinkage rate described above is replaced with the heat shrinkage rate of the fiber, if the main fiber is 4% or less, the heat shrinkable fiber needs to be heat shrunk to 9% or more. As a specific example of the heat-shrinkable fiber, an ethylene-propylene copolymer fiber obtained by stretching an ethylene-propylene copolymer, which is a block copolymer-like propylene-based random copolymer having a melting point of 138 ° C., 3-4 times, 85% thermal shrinkage (100 mm becomes 15 mm) almost instantaneously at ° C. Moreover, the eccentric sheath-core type composite fiber having the ethylene-propylene copolymer as a sheath component and the core component as a polypropylene resin has latent crimping properties, and causes severe crimping phenomenon at 130 ° C. The apparent fiber length is halved. This is also regarded as heat shrinkage in the present invention, and the heat shrinkage rate is about 50%.

  In addition, the fiber used for a general heat-bonding nonwoven fabric has a heat shrinkage rate of less than 4% at 140 ° C., and if it exceeds 4%, the texture of the nonwoven fabric is lowered due to the heat shrinkage of the fiber, and the heat bond strength is reduced. Since heat treatment is performed to suppress thermal shrinkage at the fiber production stage, the main fiber can be easily selected from these general-purpose heat-adhesive conjugate fibers. It is natural that you can make it.

The main fiber layer used in the present invention may be a single layer, but at least one side of the main filter layer for filtration is provided with a liquid-pass layer for the purpose of passing a thicker fiber. The fiber layer is preferably a fiber layer, and more preferably a fiber layer in which a liquid-permeable layer is disposed on both sides of the main filtration layer. This is because when the main fiber layers are pleated into a pleated shape and wound and compressed and thermally bonded in a compressed state, if the main fiber layers are adjacent to each other and compressed and fixed, the filtrate or the like will not easily pass. Therefore, if there is a liquid-permeable layer before and after the main filtration layer, it is preferable for smooth passage of the fluid to be filtered and for securing a place for trapping the filtered material. Also, the basis weight of the main fiber layer is 15 to 100 / m ² is conveniently if the nonwoven fabric after the winding is cut at heat rays is preferably 60 g / m ² or less. Further, when the main fiber layer is composed of a plurality of layers, the main filtration layer is preferably 20 g / m ² or more which is less likely to cause spotted spots.

Further, the heat shrinkable fiber layer preferably has a basis weight of 15 to 50 g / m ² depending on the thermal stress of the heat shrinkable fiber to be used, and is usually set to a minimum basis weight that achieves a desired increase in number. In addition, it is reasonable and preferable to melt the heat-shrinkable fiber and use it for heat-bonding between the nonwoven fabrics when forming the cylindrical filter while heat-shrinking.

  Although the heat-shrinkable fiber used in the present invention depends on the fiber of the main fiber layer to be used, 1.7 to 13 dtex is convenient, and generally 2 to 6 dtex is particularly preferable since it is opened using a card. Moreover, as a heat shrinkable fiber of the present invention, a spunbond nonwoven fabric made of a polypropylene resin having an MFR (measurement temperature of 230 ° C.), which is an index of the melt fluidity of the resin used, exceeds 100 g / 10 minutes has a large heat shrinkage. There is a tendency, and can be used as the heat-shrinkable fiber of the present invention. In spunbonded nonwoven fabrics, high MFR resin is generally used for spunbonded nonwoven fabrics of fine fibers of 3 dtex or less, resulting in fibers with large heat shrinkage. Therefore, when the spunbonded nonwoven fabric is used as a heat-shrinkable fiber layer, it is appropriate that the fibers constituting the main filtration layer of the main fiber layer be 3 dtex or less. In addition, since there is a difference in the resin used by the spunbond nonwoven fabric manufacturer and there is a difference between manufacturers in the heat shrinkage of the spunbond nonwoven fabric, it can be easily selected by investigating the heat shrinkage. Moreover, when using a spunbond nonwoven fabric as a heat-shrinkable fiber layer, it is also preferable to use a spunbond nonwoven fabric of an ethylene-propylene copolymer, and a spunbond nonwoven fabric composed of a composite fiber having an ethylene-propylene copolymer as a sheath component is used. Since the nonwoven fabric is composited, when it is heat-bonded, it is crimped to be bulky and has a large thermal shrinkage, so it has a high utility value.

  The main fiber layer is preferably a plurality of main filter layers and liquid-permeable layers, or a main filter layer alone. The main fibers to be used are fibers mainly constituting the main filtration layer, that is, fibers having the largest content in the main filtration layer, and staple fibers, meltblown nonwoven fabrics, spunbond nonwoven fabrics, airlaid nonwoven fabrics and synthetic fiber papers are preferably used. In the case of staple fibers, the fineness is limited to 1 to 100 dtex because it is necessary to go through an opening process, and in the case of spunbond nonwoven fabrics and airlaid nonwoven fabrics, 0.5 to 500 dtex, it is synthesized with meltblown nonwoven fabrics. For fiber paper, fibers having a fiber diameter of 1 to 100 μm are conveniently used. In addition, the main filtration layer is particularly preferably a good texture. In addition, when determining the size (diameter) of the required blocking particles with reference to a pleated fold filter, the cylindrical filter of the present invention is a kind of multi-stage filtration type pleated fold filter, so it is used in the corresponding pleated fold filter. A main filtration layer having a fineness greater than that of the fiber and having a low basis weight is advantageous because it can suppress an increase in pressure loss. The heat-shrinkable fiber layer and the main fiber layer have different finenesses of the fibers constituting each fiber layer, and either one forms a thick fineness fiber layer composed of thick fineness fibers, and the other has a fineness. A fine fiber layer composed of fibers is formed, and the average fineness of the thick fine fiber layer is more than twice the average fineness of the fine fine fiber layer, which is preferable because the depth filtration effect is improved.

  When the main fiber layer is a plurality of layers including a main filtration layer and a liquid passage layer, the fibers constituting the liquid passage layer are made thicker than the fibers constituting the main filtration layer for the purpose of liquid passage. It is necessary to have a function to increase the waist, increase the fiber gap, and reduce the sag at the time of winding. When made of the same material, the fineness is 1.5 times or more due to a significant difference in the waist of the fiber A thick fiber is preferable, and a fiber twice or more is more preferable. That is, it is preferable that the main fiber layer has a three-layer structure in which a thick fine fiber layer containing thick fine fibers is arranged on both surfaces of a fine fine fiber layer containing fine fine fibers. In this case, the fine fineness fiber layer forms a main filtration layer, and the thick fineness fiber layer forms a liquid passing layer. Further, as described above, it is preferable that the waist of the fiber is larger than the fiber of the main filtration layer, but it is not good that the main filtration layer is disturbed by being too thick. Generally, when the fiber of the main filtration layer is 3 dtex or less, the fiber of the liquid-permeable fiber layer is around 6 dtex, and when it is 5 to 13 dtex, the fiber is 10 to 30 dtex. In the case of 15 dtex or more, it is usual to use a fiber of 1.3 or more. However, even if the fibers of the liquid passing layer are made thicker, it is not inconvenient unless the main filtration layer is disturbed. In addition, when the heat-shrinkable fibers are thinner than the fibers of the main filtration layer, it is better to take measures such as reducing the basis weight of the heat-shrinkable fiber layer to prevent the heat-shrinkable fiber layer from becoming the main filtration layer. In general, the heat-shrinkable fiber layer that has been heat-shrinked is disturbed in texture. Therefore, if the heat-shrinkable fiber has a fineness that is more than half that of the fiber of the main filtration layer, there is little problem.

  The fibers used in the present invention are not limited to circular fibers in the vertical cross section, and there are no inconveniences if the fibers are elliptical or star-shaped or hollow fibers, and split fibers are convenient for the main fibers. Can be used well. The material constituting the fiber is preferably a polyolefin resin such as polypropylene or polyethylene resin, a polyester resin such as polyethylene terephthalate resin or polybutylene terephthalate resin, or a homopolymer or copolymer such as polyamide resin such as nylon 6. Specifically, the heat-adhesive conjugate fiber has a sheath component of high-density polyethylene, polyethylene such as medium-density polyethylene and low-density polyethylene, ethylene-propylene copolymer or polybutene-1, and polypropylene as a core component. A core-sheath type composite fiber having a melting point difference of 10 ° C. or more is convenient, and in the case of a single component fiber, a polypropylene fiber is conveniently used.

  The heat-adhesive fiber used in the main fiber layer and / or the heat-shrinkable fiber layer is a heat-adhesive fiber containing a heat-adhesive resin component. It is preferably a heat-adhesive conjugate fiber having a melting point difference of 10 ° C. or more between a low-melting point thermoplastic resin that is a heat-bonding resin component and a high-melting point thermoplastic resin that is a fiber-based component. As the heat-adhesive conjugate fiber, an eccentric or concentric sheath-core type conjugate fiber in which a majority of the fiber surface is occupied by a low-melting point thermoplastic resin is preferable, and the fiber cross-sectional shape of the core component is circular, cat-eye type, A non-circular variant such as a clover shape may be used. Furthermore, in the case of a composite fiber, it is more convenient in terms of heat bonding processing to select a resin whose melting point is at least 20 ° C. lower than that of the core component. The heat-bonding polyolefin composite fiber is ideal for filters in fields where chemical resistance such as acid resistance and alkali resistance and corrosion resistance are important. Polyethylene such as high-density polyethylene, medium-density polyethylene and low-density polyethylene, and ethylene- A core-sheath type composite fiber having propylene copolymer or polybutene-1 and having polypropylene as a core component and having a melting point difference of 10 ° C. or more is particularly preferable. When a single-component spunbond nonwoven fabric is used in combination, polypropylene fiber is used. Is particularly preferred economically.

  The cylindrical filter of the present invention is used for fluid filtration, and is highly versatile if it is made of a material that is not violated by acid or alkali. Specific examples thereof include a heat-shrinkable fiber made of a propylene-based ethylene-propylene copolymer having a melting point of 125 to 140 ° C., and the other fiber being a heat-adhesive fiber, preferably a heat-adhesive fiber being a polyolefin. It is a sheath-core type composite fiber made of a resin, and is preferably a cylindrical filter in which the thermal adhesive resin component has a melting point equal to or lower than the melting point of the ethylene-propylene copolymer.

  In another example, the heat-shrinkable fiber is composed of an ethylene-propylene copolymer mainly composed of propylene having a melting point of 125 to 140 ° C. and an eccentric sheath core type or side-by-side type composite fiber of polypropylene, and the other fiber is thermally bonded. It is preferably a cylindrical filter in which the melting point of the thermoadhesive resin component is equal to or lower than the melting point of the ethylene-propylene copolymer.

  The cylindrical filter of the present invention is also used for filtration of organic solvents such as paints. For applications where solvent resistance is required, the heat-shrinkable fiber is a copolyester resin having a melting point of 110 to 160 ° C. Is an eccentric sheath core type or side-by-side type polyester-based heat-adhesive composite fiber having a low melting point component and polyethylene terephthalate resin or polybutylene terephthalate resin as a high melting point component. The main fiber constituting the main fiber layer has a melting point of 220 ° C. A cylindrical filter which is at least one fiber selected from the above-described polyester fibers and fibers made of wet-spun or dry-spun cellulose is preferably used.

  Another preferred example is that the heat-shrinkable fibers constituting the heat-shrinkable fiber layer have a biodegradable copolymer polyester resin having a melting point of 80 to 160 ° C. as a low melting point component, and 10 ° C. higher than the melting point of the low melting point component. An eccentric sheath-core type or side-by-side type biodegradable polyester-based heat-adhesive composite fiber having a high melting point component that exceeds the biodegradable polyester resin, and the fiber constituting the main fiber layer is cellulose of wet spinning or dry spinning It is a cylindrical filter which is the fiber which consists of.

  Further, the heat-shrinkable fiber is an eccentric sheath core type or side-by-side type polyester-based heat-adhesive composite fiber in which a copolymer polyester resin having a melting point of 110 to 160 ° C. is used as a low melting point component and polyethylene terephthalate resin or polybutylene terephthalate resin The main fiber constituting the main fiber layer has an aromatic aliphatic polyester resin having a melting point of 180 to 210 ° C. as a first component, an aromatic polyester resin having a melting point of 250 ° C. or higher as a second component, and a first component. A cylindrical filter using a composite fiber in which at least a part of the component is exposed on the fiber surface is also a preferred example.

  It is preferable that the exterior nonwoven fabric wound further on the outer periphery of the said cylindrical body is further included, and an exterior nonwoven fabric consists of a heat bondable fiber, and is thermally bonded to the outer periphery of the said cylindrical body. The exterior nonwoven fabric is used as a filter material for rough filtration on the outer periphery of the cylindrical body. In order to wind and wrap the exterior nonwoven fabric, the tubular body is placed on a rotating device for winding, and the exterior nonwoven fabric is wound around the outer periphery and then rotated and rotated at a temperature equal to or higher than the thermal bonding temperature from the outside. It is good to perform partial thermocompression bonding by pressing a heating body having

  The method for producing a cylindrical filter of the present invention includes a heat-shrinkable fiber layer containing a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer containing a main fiber having a heat shrinkage rate of 4% or less. Prepare. The heat-shrinkable fiber layer and the main fiber layer are laminated to form a multilayer nonwoven fabric. At this time, the fiber layer which comprises at least one surface contains the heat bondable fiber containing a heat bond resin component. Moreover, it adjusts so that the difference of each heat contraction rate in the heat bonding temperature of a heat shrink fiber and a main fiber may be 5% or more. The multilayer nonwoven fabric may be integrated by a fiber entanglement technique such as hydroentanglement or needle punching. This is because it is easy to form a large number of ridges when contracted.

  Next, the multi-layer nonwoven fabric is heated to shrink the heat-shrinkable fiber layer to form a plurality of ridges to form a multi-layer nonwoven fabric. At this time, it is good to heat to the temperature below 5 degreeC below melting | fusing point of the thermobonding resin component of the said thermobonding fiber. Furthermore, it is wound while being heated to the heat bonding temperature of the heat-adhesive fibers constituting the multi-layered nonwoven fabric, and is wound while being integrally bonded by thermal bonding between the nonwoven fabrics with at least a heat-bonding resin component, and is molded into a cylindrical shape The body can be shaped. Preferred thermal bonding temperature is not less than the melting point of the thermoadhesive resin component (in the case of a thermoadhesive conjugate fiber, not less than the melting point of the thermoadhesive resin component (low melting thermoplastic resin) and the melting point of the high melting thermoplastic resin is less than −10 ° C.) It is wound while being heated, and the nonwoven fabric is heat-bonded at least with the heat-adhesive resin component and wound while being integrated to form a mold-shaped cylindrical body. Then, the wound multilayer nonwoven fabric is cooled as necessary, the core is removed, and a cylindrical body around which the multilayer nonwoven fabric is wound is formed.

  The cylindrical filter of the present invention will be described with reference to the drawings. FIG. 1 is an example of an enlarged cross-sectional view of a multi-layered nonwoven fabric used in the present invention. A heat-shrinkable fiber layer 1 containing heat-shrinkable fibers having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer 2 in which liquid-permeable layers 3 and 5 are laminated on both surfaces of the main filtration layer 4 are laminated and heated. The heat-shrinkable fiber layer is contracted to form a large number of ridges 6 to form a multilayer nonwoven fabric (multi-layer nonwoven fabric) 7. FIG. 2 is an example of an enlarged cross-sectional view of the cylindrical body near the outer periphery of the cylindrical body in the present invention. Adjacent multilayer nonwoven fabrics (multi-layered nonwoven fabrics) 7 are thermally bonded so as to be folded to form a cylindrical body 8.

  Examples of the present invention will be described below. The present invention is not limited to the following examples. Here, each evaluation method is as follows.

[Heat shrinkage]
(Fiber thermal shrinkage)
The heat shrinkage rate of a single fiber is 10% bundled and the length between two points is marked as 100mm. The uncrimped fiber is hung on the bottom of a wire mesh cup and heated to an arbitrary temperature. It was put in for 5 seconds, taken out, measured for the length after heat shrinkage, and calculated by the following formula.
Heat shrinkage rate (%) = [(100−length after heat shrinkage) × 100] / 100
The dry heat shrinkage was measured by applying a weight of 1 mg / d according to JIS.

(Heat shrinkage of nonwoven fabric)
When the test nonwoven fabric was fed along the conveyor and heat-treated for 20 seconds in a hot-air penetrating thermal adhesive nonwoven fabric processing machine heated to 140 ° C., the thermal shrinkage rate of the nonwoven fabric was calculated by the following formula.
If the original nonwoven fabric width is A (cm) and the nonwoven fabric width B (cm) after heat treatment,
Thermal contraction rate (%) = [100 × (A−B)] / A

[Fiber treatment agent adhesion rate]
According to the methanol extract of JIS L 1015-7.22 (6).

[Filtration life]
Test dust prepared to a concentration of 200 ppm (mixed JIS 8 types [median diameter 6.6 to 8.6 μm and 11 types [median diameter 1.6 to 2.3 μm] in a mass ratio of 1: 1, The suspension for test of Kanto Loam) was allowed to flow at a flow rate of 15 liters / minute from the outside of the cylindrical filter toward the hollow portion while stirring uniformly, and the water flow pressure for maintaining this flow rate was 0.2 MPa. Expressed as total water flow (liters) when

[Filtration accuracy]
A particle size distribution measuring device (trade name) is used to determine the number (M) of each dust particle size contained in a predetermined amount of the test suspension and the number (N) of each dust particle size remaining in the liquid after filtration. : Coulter counter ZM type: manufactured by Coulter Electronics Co., Ltd.). The blocking rate was calculated from the following formula for each particle size. The blocking rate is 100% above a certain particle size. The particle diameter (r) at which the blocking rate immediately before that was 99% was defined as the filtration accuracy.
Blocking rate (%) = [(MN) × 100] / M
The filtration accuracy indicates that the smaller the r, the more fine particles can be captured by the filter.
The suspension for testing was a dust water dispersion in which 50 ppm of JIS 7 [median diameter 27 to 31 μm] and JIS 8 [median diameter 6.6 to 8.6 μm] were mixed at a mass ratio of 1: 1. Filtration was performed at a flow rate of 40 liters / minute, and the filtrate was measured for 5 minutes after the start of filtration.

[Water pressure loss]
The pressure difference between the inlet and outlet of the filter when water was passed at a flow rate of 40 liters / minute was measured and displayed in (KPa).

Below, the fiber used by an Example and a comparative example is shown.
(Heat shrink fiber)
An ethylene-propylene copolymer (EP) having a propylene content of 96% by mass, a melting point of 136 ° C. and an MFR of 230 ° C. of 15 g / 10 min was melt-spun at 265 ° C., and 3.2 times in hot water at 90 ° C. Next, a fiber treatment agent containing an antistatic agent or the like was applied, and mechanical crimping was applied with a stuffing box, followed by drying with a conveyor type hot air through dryer at 60 ° C. and cutting into 51 mm. Staple fibers of 4 dtex (EP1 fiber), 8 dtex (EP2 fiber), and 15 dtex (EP3 fiber) were used. The EP1 to EP3 fibers exhibited a single fiber heat shrinkage of 45% at 130 ° C. (100 mm became 55 mm), 85% at 140 ° C., and 92% at 150 ° C. On the other hand, the dry heat shrinkage applied with a load of 1 mg / d according to JIS was 50% at 130 ° C., 70% at 140 ° C., and 76% at 150 ° C. for 4 dtex EP1 fiber. The thermal stress of 4 dtex EP1 fiber was 15 gf / dtex at 100 ° C., 25 gf / dtex at 120 ° C., and 20 gf / dtex at 140 ° C. In addition, these EP fibers are melted granular when exposed to 150 ° C. after being thermally contracted, and can be used for thermal bonding when a little pressing pressure is applied.

(Heat bonding / heat shrinkable composite fiber)
The heat-bonding / heat-shrinkable composite fiber uses the above-mentioned EP resin as a core component, and the sheath component uses a linear low density polyethylene having a melting point of 122 ° C. and a 190 ° C. MFR of 20 g / 10 min. 1: 1 eccentric sheath-core type composite fibers were made into 6 dtex staple fibers (EL fibers) in the same manner as the EP fibers. The dry heat shrinkage rates at 120 ° C. and 140 ° C. were 10% and 25%, respectively. The single fiber heat shrinkage under no load was 35% at 140 ° C.

  Also, a resin obtained by mixing 50% by mass of the EP resin with 50% by mass of an ethylene-propylene-butene-1 terpolymer resin having a melting point of 138 ° C. and an MFR of 230 ° C. of 12 g / 10 min is used. A 4 dtex staple fiber (EPB fiber) was produced in exactly the same manner as the EP fiber. Its single fiber heat shrinkage at 140 ° C. was 30%.

  A staple fiber (PP fiber) in which 60% by mass of a homopolymer polypropylene resin commercially available for a comparative example and 40% by mass of the EP resin were mixed was prepared in the same manner as the EP fiber. Its single fiber heat shrinkage at 140 ° C. was 8%.

(Latent crimped fiber)
50% by mass of the EP resin as a sheath component, and a 4dtex composite fiber of a sheath core type in which a polypropylene resin having a melting point of 163 ° C. and an MFR of 230 ° C. of 30 g / 10 min as a core component is greatly eccentric at 50% by mass. Was made into staple fibers (CPP fibers) in the same manner as EP fibers. The stretching temperature was 60 ° C. and the stretching ratio was 3.5 times. The single fiber heat shrinkage rate at 140 ° C. was 20%, and severe three-dimensional fine crimps were generated, resulting in bilateral crimps in which the fine coils were swirled into a larger coil shape.

(Thermoadhesive conjugate fiber)
A heat-adhesive conjugate fiber (trade name NBF, manufactured by Daiwabo Co., Ltd.) having a polyethylene resin as a sheath component and a core component as a polypropylene resin was used. Its single fiber heat shrinkage at 140 ° C. was 1%.

(Thermal bonding and splitting composite fiber)
A split type fiber (DF7, manufactured by Daiwabo Co., Ltd.) was used, which was composed of only a polyolefin resin in which the cross section of the fiber having a polyethylene resin as one component and the other component as a polypropylene resin was radial like mikan. The single fiber heat shrinkage at 140 ° C. was 2% or less.

  Further, a heat-splitting fiber (TF15) that can be divided by heat and that has a fiber cross-section in a radial shape like tangerine, in which polyethylene terephthalate resin is one component and the other component is the above-described EP resin was used. The single fiber heat shrinkage at 140 ° C. was 2% or less.

(Non-thermal adhesive single fiber)
Polypropylene fiber (PP fiber) made of polypropylene resin was used. The single fiber heat shrinkage at 140 ° C. was 2% or less.

(Spunbond nonwoven fabric with thermal shrinkage)
Polypropylene spunbond nonwoven fabric (SB1) PK103 made by Mitsui Chemicals Co., Ltd. was used. The thermal contraction rate in the width direction at 140 ° C. was 15%.

(Spunbond nonwoven fabric that does not expect thermal shrinkage)
A 2 dtex spunbonded non-woven fabric (SB2) of a heat-adhesive conjugate fiber using a polyethylene resin manufactured by Chisso Corporation as a sheath component and a core component as a polypropylene resin was used. The thermal contraction rate in the length direction at 140 ° C. was 2%.

[Example 1]
The fibers used were individually opened using roller cards to form webs. First, a card web made of NBF (thick fine fiber) having a basis weight of 13 g / m ^{2 and} a fineness of 6 dtex on both sides of a card web made of NBF (fine fine fiber) having a basis weight of 15 g / m ^{2 and} a fineness of ² dtex. Are laminated to form a three-layer laminated web so that the fine fiber layer becomes a main filtration layer and the thick fiber layer becomes a liquid-permeable layer. A card web made of 4 dtex EP1 fibers with a basis weight of 15 g / m ² is used as the heat-shrinkable fiber layer. A main fiber layer (laminated web) is laminated on the heat-shrinkable fiber layer on a net conveyor, and pressure water of 4 MPa. Then, hydroentangled from both the upper and lower sides to produce a fiber entangled nonwoven fabric (multilayer nonwoven fabric) having a thickness of about 1 mm. After this multi-layered nonwoven fabric is sufficiently drained using a slit type suction box, it is over-feeded in a net conveyor type hot air penetration dryer at 135 ° C. in an unrestrained state, and dried and heat-shrinked. EP1 A multi-layered nonwoven fabric having a basis weight of 130 g / m ² and an apparent thickness of 4 mm, in which the fibers were heat-shrinked to form a large number of ridges on a three-layer laminated web, was produced.

  Next, the mold mold was wound around an iron core having an outer diameter of 28 mm by passing it through a hot air penetration type dryer heated to 145 ° C. having a mechanism for winding the multi-layered nonwoven fabric around the cartridge filter. A cylindrical body was produced. The width of the multi-layered non-woven fabric as a cartridge filter with a grooved groove by pressing it with a metal roller with a ring-shaped circumferential protrusion protruding to a height of about 1 mm every 10 mm while it is still hot The cut surface extending in the direction was pressed and finished, and cut to a length of 250 mm to obtain a cylindrical filter of the present invention. The obtained filter with the heat-shrinkable fiber layer as the inner winding has a filtration accuracy of 5 μm, a filtration life of 700 liters, and a water pressure loss of 5 KPa. The performance was improved. A cartridge filter having a heat-shrinkable fiber layer as an outer winding was also produced and performance was evaluated, but the results were almost the same.

[Example 2]
In Example 1, using a device in which a net conveyor type hot air penetrating dryer for drying and a hot air penetrating dryer heated to 145 ° C. having a mechanism for winding up on a cartridge filter were connected, other conditions were as in Example 1. In the same manner as described above, shrinkage processing and heat bonding processing were continuously performed to obtain a cylindrical filter of the present invention. In the same manner as in Example 1, when the outer shrinkage and the inner shrinkage of the heat-shrinkable fiber layer were evaluated, the performance was almost the same as in Example 1.

[Example 3]
A cylindrical filter of the present invention having a heat-shrinkable fiber layer as an inner winding was obtained in the same manner as in Example 1 except that NBF fibers having a fineness of 1 dtex were used instead of the fineness fibers of Example 1. The filtration accuracy of the cartridge filter having the heat-shrinkable fiber layer as the inner winding is 4 μm, the filtration life is 600 liters, and the water pressure loss is 6 KPa. The filtration accuracy is further improved as compared with the tubular filter of Example 1. It was.

[Example 4]
Instead of each fiber of Example 1, as the main fiber layer, NBF with a fineness of 15 dtex with a basis weight of 13 g / m ^{2 and} a fineness of 15 dtex on each side of the card web made of NBF (fine fineness fiber) with a fineness of 10 dtex with a basis weight of 25 g / m ² Example 3 except that a three-layer laminated web is used by laminating card webs made of thick fine fibers) and a card web made of 15 dtex EP3 fibers having a basis weight of 15 g / m ² is used as the heat-shrinkable fiber layer. By this method, the cylindrical filter of the present invention having the heat-shrinkable fiber layer as an inner winding was obtained. This cartridge filter had a filtration accuracy of 15 μm, a filtration life of 1600 liters, and a water pressure loss of 2 KPa.

[Example 5]
Instead of the fine fiber used in Example 1, using a fineness of 2.5 dtex, DF7 of 8 split type, except that the hydroentangled water pressure was raised to 7 MPa, the same method as in Example 1, A cylindrical filter of the present invention having a heat-shrinkable fiber layer as an inner winding was obtained. The filtration accuracy of this cartridge filter was 2 μm, the filtration life was 500 liters, and the water pressure loss was 7 KPa. The filtration accuracy was further improved over the cartridge filter of Example 3.

[Example 6]
A cylindrical shape of the present invention having a heat-shrinkable fiber layer as an inner winding in the same manner as in Example 1 except that TF15 having a fineness of 2 dtex and an 8-split type is used in place of the fineness fiber used in Example 1. A filter was obtained. Although this cartridge filter had a water pressure of 4 MPa similar to that of Example 1, the filtration accuracy was 4 μm, while that of 6 MPa similar to Example 5 was 3 μm, the filtration accuracy was improved to 5 KPa. This is presumed to be caused by heat shrinkage of half of the ultrafine fibers.

[Example 7]
In place of the fine fiber layer used in Example 1, a composite fiber spunbond nonwoven fabric SB2 having a basis weight of 20 g / m ^{2 and} a fineness of ² dtex was used. A cylindrical filter of the present invention to be wound was obtained. The performance was almost the same as in Example 1.

[Example 8]
The heat-shrinkable fiber layer was internally wound in the same manner as in Example 1 except that polypropylene fibers (PP fibers) having a basis weight of 20 g / m ^{2 and} a fineness of ² dtex were used instead of the fineness fibers used in Example 1. A cylindrical filter of the present invention was obtained. The performance was almost the same as in Example 1.

[Example 9]
Instead of the heat-shrinkable fiber layer of Example 8, a polypropylene spunbond nonwoven fabric (SB1) PK103 having a basis weight of 16 g / m ^{2 and} a fineness of slightly less than 6 dtex was used. The multi-woven fabric produced at this time is a form in which wrinkles extend in the longitudinal direction of the non-woven fabric, and the difficulty is that if the width of the nonwoven fabric is widened, wrinkles are not likely to enter the central part in the width direction of the nonwoven fabric, but it is almost uniform at 30 cm width. It was possible to form a cocoon. Using this 30 cm wide multi-layered nonwoven fabric, a cylindrical filter of the present invention having a heat-shrinkable fiber layer as an outer winding was obtained in the same manner as in Example 8. The obtained cartridge filter had a filtration accuracy of 8 μm, a filtration life of 800 liters, and a water passage pressure loss of 7 KPa. The performance of the filtration life and water passage pressure loss was improved as compared with the conventional mold-type cartridge filter.

[Example 10]
In place of the heat-shrinkable fiber layer of Example 1, a multi-woven fabric was produced in the same manner as in Example 1 except that latent crimpable fibers (CPP fibers) having a fineness of 4 dtex were used. This multi-layered nonwoven fabric is not only multi-layered but also a heat-shrinkable fiber layer that is a collection of fine crimps that stretch slightly, and heat-shrinkable fiber layer on a conveyor heated to prevent tension As a result, the cylindrical filter of the present invention was obtained. When this was evaluated, the depth filtration effect was larger than in Example 1, and the filtration life was 900 liters.

[Example 11]
In Example 1, an NBF fiber web layer having a basis weight of 20 g / m ^{2 and} a fineness of ² dtex was placed on the heat-shrinkable fiber layer, and an NBF fiber web layer having a fineness of 4 dtex was laminated to form a three-layered web. A cylindrical filter of the present invention was obtained by the same method. The resulting cartridge filter had a filtration accuracy of 6 μm, a filtration life of 700 liters, and a water pressure loss of 7 KPa.

[Example 12]
In Example 11, the tubular filter of the present invention was prepared in the same manner as in Example 11 except that the heat-shrinkable fiber was replaced with 8 dtex EP2 fiber and 8 dtex NBF fiber was used instead of 4 dtex NBF fiber. Obtained. The resulting cartridge filter had a filtration accuracy of 6 μm, a filtration life of 800 liters, and a water pressure loss of 6 KPa.

[Example 13]
An NBF fiber web with a basis weight of 30 g / m ^{2 and} a fineness of ² dtex is laminated on the fiber web of heat-shrinkable fiber EP1 with a basis weight of 15 g / m ^{2 and} a fineness of 4 dtex, and dried in the same manner as in Example 1 with 3 MPa pressure water. The hydroentangled nonwoven fabric having a thickness of 2 mm shown in FIG. This was wound with the heat-shrinkable fiber layer as the outside to obtain a cylindrical filter of the present invention. The resulting cartridge filter had a filtration accuracy of 13 μm, a filtration life of 600 liters, and a water pressure loss of 10 KPa.

[Comparative Example 1]
An NBF fiber web having a basis weight of 40 g / m ^{2 and} a fineness of ² dtex was made into a hydroentangled nonwoven fabric dried by 3 MPa pressure water in the same manner as in Example 1, and this was wound to obtain a cartridge filter. The resulting cartridge filter had a filtration accuracy of 15 μm, a filtration life of 400 liters, and a water pressure loss of 13 KPa.

[Comparative Example 2]
A composite fiber spunbonded nonwoven fabric SB2 having a basis weight of 20 g / m ^{2 and} a fineness of ² dtex was directly wound in accordance with Example 1 to obtain a cartridge filter. The obtained cartridge filter was tightly wound and weighed 1.3 times that of the comparative example. When this was evaluated, it was a surface layer filtration in which the filtrate was thinly attached to the surface of the cartridge filter. The accuracy was as high as 5 μm, but the filtration life was 100 liters, and the water pressure loss was 18 KPa.

  Part of these cylindrical filters are scraped off, and the presence or absence of the fiber treatment agent (surfactant) is extracted with methanol to measure the surfactant adhesion rate. It was estimated that most of these were due to oligomers deposited on the fiber surface, although less than mass loss occurred. In addition, even if it actually flowed through, there was no foaming of the passage liquid at all.

  When the cylindrical filter of the example was actually filtered using a brown powder until the water flow pressure became 0.2 MPa, it was colored brown to the vicinity of the central cavity. On the other hand, the thing of the comparative example 1 was colored only about 5 mm from the outer periphery, and it has confirmed that the cylindrical filter of an Example was deeply filtered compared with the comparative example 1. FIG.

  The cylindrical filter of the present invention is used in various applications such as filtration of purified water used in the pharmaceutical industry and electronics industry, filtration in the production process of alcoholic beverages in the food industry, and filtration of coating agents in the automobile industry. It can be used economically.

It is an example of the cross-sectional enlarged view of the multi-layered nonwoven fabric used for this invention. It is an example of the cylindrical body cross-sectional enlarged view of the cylindrical body outer periphery vicinity in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat-shrinkable fiber layer 2 Main fiber layer 3, 5 Liquid passing layer 4 Main filtration layer 6 Saddle 7 Multi-layer non-woven fabric
8 Cylindrical body

Claims (11)

A cylindrical filter comprising a cylindrical body wound with a multilayer nonwoven fabric composed of a plurality of fiber layers, wherein adjacent multilayer nonwoven fabrics are thermally bonded to each other,
The multilayer nonwoven fabric includes a heat-shrinkable fiber layer including a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer including a main fiber having a heat-shrinkage rate of 140% or less at 4%. The fiber layer constituting at least one surface of the layer nonwoven fabric includes a thermoadhesive fiber containing a thermoadhesive resin component,
The multilayer nonwoven fabric, Ri Tashiwa nonwoven der to form multiple wrinkle-like material by thermal contraction,
Cylindrical filter ing and integrated by thermal bonding between the multilayer nonwoven fabric in at least the heat-adhesive resin component. The thermoadhesive fiber is a thermoadhesive conjugate fiber that includes a low-melting-point thermoplastic resin that is a thermal-adhesive component and a high-melting-point thermoplastic resin that is a fiber-based component, and has a melting point difference of 10 ° C or more. cylindrical filter according to 1. The heat-shrinkable fiber constituting the heat-shrinkable fiber layer is an eccentric sheath core type in which a copolyester resin having a melting point of 110 to 160 ° C. is a low melting point component, and a polyethylene terephthalate resin or polybutylene terephthalate resin is a high melting point component It is a side-by-side polyester thermal adhesive composite fiber,
Fibers constituting the main fiber layer is at least one fiber selected from polyester fibers, and fibers of cellulose wet spinning or dry spinning of a melting point and 220 ° C. or higher, according to claim 1 or 2 Tubular filter. The heat-shrinkable fiber constituting the heat-shrinkable fiber layer comprises a biodegradable copolymer polyester resin having a melting point of 80 to 160 ° C. as a low melting point component, and a biodegradable polyester resin having a melting point of 10 ° C. higher than the melting point of the low melting point component. It is an eccentric sheath core type or side-by-side type biodegradable polyester-based heat-adhesive conjugate fiber with a high melting point component,
The cylindrical filter according to claim 1 or 2 , wherein the fiber constituting the main fiber layer is a fiber made of wet-spun or dry-spun cellulose. The heat-shrinkable fiber constituting the heat-shrinkable fiber layer is an eccentric sheath core type in which a copolyester resin having a melting point of 110 to 160 ° C. is a low melting point component, and a polyethylene terephthalate resin or polybutylene terephthalate resin is a high melting point component It is a side-by-side polyester thermal adhesive composite fiber,
The fiber constituting the main fiber layer has an aromatic aliphatic polyester resin having a melting point of 180 to 210 ° C. as a first component, an aromatic polyester resin having a melting point of 250 ° C. or more as a second component, The cylindrical filter according to claim 1 or 2 , wherein at least a part is a composite fiber exposed on the fiber surface. The cylindrical filter according to any one of claims 1 to 5 , wherein the multilayer nonwoven fabric is integrated by hydroentanglement, and the amount of the fiber treatment agent attached to the multilayer nonwoven fabric is 0.05% by mass or less. The heat-shrinkable fiber layer and the main fiber layer are different in the fineness of the fibers constituting each fiber layer, either one forms a thick fineness fiber layer composed of thick fineness fibers, and the other consists of fineness fineness fibers. The cylindrical filter according to any one of claims 1 to 6 , wherein a fine fineness fiber layer is formed, and an average fineness of the thick fineness fiber layer is twice or more an average fineness of the fine fineness fiber layer. The multilayer nonwoven fabric, the main fiber layer is a three layer structure formed by arranging a large fineness fiber layer comprising a large fineness fibers on both surfaces of the fine denier fiber layer comprising fine denier fibers, any of claim 1-7 The cylindrical filter of crab. The cylindrical filter according to any one of claims 1 to 8 , wherein any one of the fiber layers constituting the multilayer nonwoven fabric is a spunbond nonwoven fabric. It further includes an exterior nonwoven fabric wound around the outer periphery of the cylindrical body,
The cylindrical filter according to claim 1, wherein the exterior nonwoven fabric is made of the thermoadhesive fiber and is thermally bonded to an outer periphery of the cylindrical body. A method for producing a cylindrical filter comprising a cylindrical body wound with a multilayer nonwoven fabric composed of a plurality of fiber layers, wherein adjacent multilayer nonwoven fabrics are thermally bonded to each other,
The multilayer nonwoven fabric includes a heat-shrinkable fiber layer including a heat-shrinkable fiber having a heat shrinkage rate of 9% or more at 140 ° C. and a main fiber layer including a main fiber having a heat-shrinkage rate of 140% or less at 4%. The fiber layer constituting at least one surface of the layered nonwoven fabric includes a thermoadhesive fiber containing a thermoadhesive resin component, and the melting point of the thermoadhesive resin component is from −5 ° C. to the melting point of the resin having the highest melting point of the main fiber. difference in thermal shrinkage between the heat-shrinkable fibers and main fibers at a temperature in the range of up to 10 ° C. is not less than 5%,
The multi-layer non-woven fabric is formed by heating the multi-layer non-woven fabric to a temperature lower than the melting point of the heat-adhesive resin component of the heat-adhesive fiber by 5 ° C. or more to shrink the heat-shrinkable fiber layer to form a plurality of cocoons. And
The multi-layered nonwoven fabric is heated at the heat bonding temperature of the heat-adhesive fiber and wound around a core while at least the heat-bonding resin component is integrated by thermal bonding between the multilayered nonwoven fabrics ,
The manufacturing method of the cylindrical filter which extracts the said core from the wound said multilayer nonwoven fabric, and forms the cylindrical body by which the said multilayer nonwoven fabric was wound.

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