JP2017080712A - Pleat filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pleat filter having a longer filtration life even to gelatinous fluid having a higher viscosity or highly viscous slurry, and excellent in filtration accuracy and pressure resistance.SOLUTION: There is provided a cylindrical pleat filter. In the pleat filter, a filter material of the pleat filter is a pleated nonwoven fiber assembly with a thickness of 3 mm or more comprising thermoplastic fibers, and a compressibility of the filter material is 0.2 or less when a load of 0.5 MPa is applied thereto, and the nonwoven fiber assembly of the filter material of the pleat filter has fused fiber intersections.SELECTED DRAWING: None

Description

  The present invention relates to a cylindrical pleated filter having a filter material folded in a pleat shape.

  A pleated filter is known as one of filters for removing fine particles and solids contained in a fluid. The pleated filter secures a large filtration area by folding the filter medium into a pleated shape (also called fold folding or pleating), and the time until the surface of the filter medium is covered with the filtrate increases. A long-life filter can be obtained.

  Patent Document 1 discloses a pleated filter that extends filter life and improves filter medium strength and filtration accuracy stability. The use of a sheet as a filter medium is disclosed. The non-fine fiber mixed non-woven fiber assembly sheet is characterized in that fiber intersections are thermally bonded and a fiber diameter gradient is formed between the surface layer portion and the back layer portion.

  In the pleated filter of Patent Document 1, a fiber diameter gradient is imparted to the fibers forming the filter medium from the surface layer portion to the back surface portion, thereby forming a pore diameter gradient as a filtration function. It is thought that it will be possible to capture and the filtration life will be improved. Further, by using a composite fiber or a mixed fiber made of a high melting point resin and a low melting point resin, the fiber intersections are integrated by heat treatment. As a result, the strength of the filter medium is increased, deformation of the pleats (pleats) is prevented, and the movement between the fibers is suppressed, so that stable filtration accuracy can be obtained.

  In Patent Document 2, as a pleated filter, a woven fabric made of a heat-adhesive composite monofilament and a heat-adhesive fiber are entangled and dispersed through a mesh of the mesh to form a nonwoven fabric. Has a thickness larger than that of the ridge, and a contact between fibers and a contact between fibers and a mesh are thermally bonded, and the mesh and the nonwoven fabric are joined and integrated.

  In the pleated filter of Patent Document 2, first, a net-like body such as a heat-adhesive composite monofilament is produced and pleated. Subsequently, a non-woven fabric layer is formed on the mesh body by a melt blown method or a spun bond method, and heat treatment is performed to obtain a filter medium in which the mesh body and the nonwoven fabric layer are integrated. At this time, the thickness of the pleat valley and peak is changed by controlling the amount of the nonwoven material laminated. According to the invention of Patent Document 2, it is disclosed that a decrease in filtration life due to deformation of pleats due to long-term use can be reduced by a nonwoven fabric laminated in a large amount in valleys.

Each of the pleated filters of Patent Documents 1 and 2 is a cylindrical filter having an outer diameter of about 60 to 70 mm and a pleat crest number of about 100 to 120, and the basis weight of the filter medium is about 50 to 200 g / m ² . Further, in Patent Documents 1 and 2, the filtration life is confirmed only with a test fluid using water as a dispersion medium, and no consideration is given to the filtration of viscous fluids. In fact, such a filter is suitable for filtering water and low-viscosity fluids, but not necessarily suitable for filtering high-viscosity slurries and gel fluids.

  Patent Document 3 discloses that, in a pleated filter, a sheet-like filter material in which support members are stacked on both sides is pleated and used as a filter. The filter of Patent Document 3 is intended to prevent the shape of the filter from being deformed by the filtration pressure, particularly when filtering a highly viscous fluid, and is supported by using a synthetic fiber nonwoven fabric as a sheet-like filter material. As the member, a wire mesh using a metal wire, a non-woven fabric using a metal wire, or the like is used.

  The filter of Patent Document 3 is a disk-shaped filter suitable for being integrally assembled together with a base as a member of a spinning pack for filtering and spinning a polymer high-viscosity fluid in the production of synthetic fibers, and is cylindrical. It is not about filters. Moreover, although the filter of patent document 3 is improving the intensity | strength of filter material by use of a metal wire, use of a metal may not be preferable depending on the use of a filter, and it cannot necessarily be said to be general purpose. It was. In addition, this was simply a stack of sheets, and the three-dimensionally entangled fiber molded product was not thick. For this reason, even if the apparent pressure strength is excellent, when filtering with a high viscosity fluid or the like at high pressure, the filter material may be opened and foreign matter may flow out.

JP-A-11-90135 JP 2000-271417 A WO2003 / 099417 publication pamphlet

  Various configurations have been proposed for the pleated filter as described above, but the cylindrical shape has a long filtration life and excellent filtration accuracy and pressure resistance even for highly viscous gel fluids and high viscosity slurries. There was not enough as a pleated filter. That is, an object of the present invention is to provide a pleated filter having a long filtration life and excellent filtration accuracy and pressure resistance even for viscous fluids in a cylindrical filter.

  The inventors have repeatedly studied to solve the above-mentioned problems, and in the pleated filter, the thickness of the filter material is large, and by adopting a depth filter that can capture particles not only on the surface but also inside the filter material, Has been found to exhibit an excellent effect on filtration of high viscosity liquids. Then, the thickness of the filter material is set to 3 mm or more, and at the same time, the compression rate is low (the compression rate when the load of 0.5 MPa is applied is 0.2 or less), that is, a hard filter, in particular, the fiber intersection of the filter material is melted. It has been found that by having a worn configuration, not only the filtration life is long and the pressure resistance is improved, but also the filtration accuracy is improved, and the present invention has been completed.

That is, the present invention has the following configuration.
[1] A cylindrical pleated filter, wherein the filter material of the pleated filter is a woven folded fiber assembly having a thickness of 3 mm or more made of thermoplastic fiber, and the filter material has a load of 0.5 MPa. A pleated filter having a compression ratio of 0.2 or less when applied.
[2] Cylindrical pleated filter, wherein the filter material of the pleated filter is a folded woven nonwoven fiber aggregate having a thickness of 3 mm or more made of thermoplastic fiber, and the nonwoven fiber aggregate is a fiber Pleated filter with fused intersections.
[3] The pleated filter according to [1] or [2], wherein the thermoplastic fiber is a composite fiber composed of two or more components having different melting points.
[4] The pleated filter according to [1] or [2], wherein the thermoplastic fiber is a mixed fiber of two or more components having different melting points.
[5] The pleated filter according to any one of [1] to [4], wherein an outer diameter of the pleated filter is 50 to 80 mm.
[6] The pleated filter according to any one of [1] to [5], wherein the height of the pleat mountain is 7 to 20 mm.
[7] The nonwoven fiber aggregate is composed of one or a combination of two or more selected from the group consisting of tangled short fibers, meltblown nonwoven fabrics, and spunbond nonwoven fabrics. [1] to [6] The pleated filter according to any one of the above.
[8] The nonwoven fiber assembly includes a web made of at least one layer of parallel type composite fibers, and a spunbond nonwoven fabric laminated on both surfaces of the web, and the web and the spunbond nonwoven fabric are integrated. The pleated filter according to [7].
[9] (1) A step of producing a nonwoven fiber assembly having a thickness of 3 mm or more made of thermoplastic fibers;
(2) fold-folding the non-woven fiber assembly;
(3) The non-woven fiber assembly folded in the above-described step is wound around a cylindrical core, and both ends along the axial direction of the core of the non-woven fiber assembly are combined to make a filter endless in the circumferential direction The process of making the material,
(4) attaching a cap to both ends of the core around which the filter material is wound to form a cylindrical filter;
(5) including, to the cylindrical filter obtained in the step (4), a step of applying a temperature equal to or higher than at least one melting temperature of the thermoplastic fibers.
Pleated filter manufacturing method.

According to the present invention, it is possible to provide a pleated filter not only having a long filtration life and excellent pressure resistance even for a highly viscous fluid, but also having high filtration accuracy. The pleated filter of the present invention can be suitably used for applications such as filtration of highly viscous liquids such as paints and coating agents.
Further, in the pleated filter of the present invention, the one where the fiber intersection is bonded by fusing the thermoplastic fiber constituting the filter material does not contain an adhesive or the like other than the resin constituting the thermoplastic fiber. This is advantageous in terms of quality control of the object to be filtered because the risk of contamination and contamination is low. In addition, the filter is advantageous in terms of cost and manufacturing control because it has a small number of manufacturing raw materials in the filter manufacturing process. Further, there is no decrease in the aperture ratio of the filter material due to the adhesive. Further, there is no risk of the filter material falling off due to lack of adhesive or unevenness.

  The pleated filter of the present invention is a cylindrical pleated filter. Cylindrical pleated filters are made by winding a filter material that has been repeatedly folded and folded by fold folding around the outer periphery of a cylindrical core so that the ridgeline direction is the axial direction of the filter. It has a structure in which the sides are joined to make them endless and caps are attached to both ends.

  In the present specification, the outer diameter of the pleated filter refers to the diameter of a virtual circle that connects the tops of the pleat peaks. The height of the pleat mountain is a half of the difference in diameter between a virtual circle connecting the tops of the pleat mountain and a virtual circle connecting the bottoms of the pleat valleys.

  In the present invention, the outer diameter of the filter is preferably 50 to 80 mm, and more preferably 60 to 70 mm. If it is this range, the effect only commensurate with processing effort will be acquired compared with the thing without a pleat. If it is 60-70 mm, since it can be used as a standard filter of the existing filtration equipment, it is especially preferable.

The filter material of the present invention is a member having a filtration function among members constituting the pleated filter, and is composed of a nonwoven fiber assembly. The nonwoven fiber aggregate is an aggregate in which one or a plurality of nonwoven fabrics (including a nonwoven net, a nonwoven sheet, a nonwoven film, etc.) are overlapped and integrated. ~ 25 sheets can be overlapped. When a plurality of non-woven fabrics are overlapped, one type of non-woven fabric may be used, or two or more types may be used in combination. Basis weight of the nonwoven fiber aggregate is not particularly limited as long to obtain a desired filtration performance, for example, is preferably 700~1500g / ^{m 2,} and more preferably 830~1330g / ^{m 2.}

  The thickness of the nonwoven fiber assembly is 3 mm or more, preferably about 3 mm to 10 mm, and more preferably 3 to 5 mm. If the thickness of the non-woven fiber aggregate is 3 mm or more, foreign matters can be collected more firmly, and a sufficient effect can be obtained without passing through the gel-like material. The thickness direction of the nonwoven fiber assembly is the filtrate passage direction. The pleated filter of the present invention is a so-called depth filter.

  The density of the nonwoven fibers in the thickness direction of the nonwoven fiber assembly may be constant or may have a density gradient. When there is a sparse / dense gradient, for example, the upstream side can be made sparse and the density can be made closer to the downstream side. Further, the life near the downstream side is sparse so as to facilitate the back flow, or the dense portion is prevented from being excessively closely contacted, whereby the filtration life can be further extended.

  The height of the mountain of the nonwoven fiber assembly is preferably 7 to 20 mm. Since a non-woven fiber assembly forms a mountain by folds, the height of the mountain is limited by the thickness of the non-woven fiber assembly, and the height of the mountain is more than twice the thickness of the non-woven fiber assembly. Become. Typically, it is preferable that the thickness of the nonwoven fiber assembly is about 3 to 5 mm and the height of the mountain is about 10 to 15 mm.

  The number of peaks of the pleated filter of the present invention may be appropriately selected depending on the diameter of the cylindrical core, the desired filtration area, the thickness of the filter material that is the nonwoven fiber assembly, etc. When the thickness of the non-woven fiber aggregate is about 3 to 5 mm, it is preferable that 12 to 18 peaks are arranged on the circumference.

In the pleated filter of the present invention, the compression ratio when at least a part of the layer of the filter material is subjected to a load of 0.5 MPa is 0.2 or less, and more preferably 0.1 or less. The pleated filter of the present invention is a depth filter and is characterized by a low compression rate, that is, a hard filter. By adopting such a configuration, it is considered that the pressure resistance is high, and further, the deformation of the filter material with use is reduced, and the movement and displacement between fibers in the filter is reduced, so that the filtration accuracy is improved. Yes. A method for measuring the compression rate will be described in detail later.
In order to prevent excessive adhesion of the filter material or to prevent the filter material from collapsing during molding, a high porosity sheet for providing a gap in the upstream side, downstream side, intermediate portion, etc. of the filter material is provided. You may overlap. As such a sheet, a spunbonded nonwoven fabric or a net is preferable.

  The nonwoven fiber assembly is made of thermoplastic fibers. Examples of the thermoplastic fiber include various polyolefins such as polyethylene and polypropylene, thermoplastic polyesters such as polyethylene terephthalate, and polyamides such as nylon 6 and nylon 66, and polyolefin is particularly preferable from the viewpoint of chemical resistance.

  Examples of the polyolefin include homopolymers such as ethylene, propylene, butene-1, or 4-methylpentene-1, and these and other α-olefins, that is, ethylene, propylene, butene-1, pentene-1, hexene- A random or block copolymer with one or more of 1 or 4-methylpentene-1, a copolymer obtained by combining these, or a mixture thereof. Among these, it is preferable to use polyethylene and polypropylene in terms of chemical resistance.

  Polyamides include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 610, polymetaxylidene adipamide, polyparaxylidene decanamide, polybiscyclohexylmethane decanamide or copolyamides thereof. Etc. Examples of the polyester include polyethylene terephthalate, polytetramethylene terephthalate, polybutyl terephthalate, polyethyleneoxybenzoate, poly (1,4-dimethylcyclohexane terephthalate), and copolymers thereof.

  The filter material of the pleated filter of the present invention is preferably composed of an aggregate of nonwoven fibers entangled with the thermoplastic fibers, and the fiber intersections (entanglement points) are preferably fused. Here, the fusion means that at least a part of the single fibers contained in the non-woven fiber assembly melt and adhere to other single fibers, and then solidify to fix the single fibers. Of the fiber intersections in the nonwoven fiber assembly, 50% or more should be fused, 70% or more is preferably fused, and almost 100% of the fiber intersections are fused. Is more preferable. The fusion of fiber intersections can be confirmed, for example, with an electron microscope, and the proportion of fiber intersections fused can be calculated.

  As the thermoplastic fiber constituting the non-woven fiber assembly, it can be used as a single component, but when considering the effect of fusion at the intersection of the heat-adhesive fibers, the low melting point resin and the high melting point resin It is preferable to use a fiber composed of a composite component, that is, a composite fiber composed of two or more components having different melting points. If the difference between the melting points of the two components is 10 ° C. or more, it is preferable because management during the heat bonding process is easy. In the case of a composite fiber, a composite fiber in which a low melting point resin continuously occupies at least a part of the fiber surface is easy to form by thermal bonding, and the fiber shape other than the intersection point is not greatly impaired after bonding. If the fiber shape of the same cross-sectional shape is maintained, it is preferable.

  The composite ratio (weight ratio) of the high melting point resin and the low melting point resin is preferably 70:30 to 30:70 from the viewpoint of adhesive strength and adhesiveness. Examples of composite component resin combinations include high density polyethylene / polypropylene, linear low density polyethylene / polypropylene, binary copolymers of propylene and other α-olefins or terpolymers / polypropylene, linear Low density polyethylene / high density polyethylene, low density polyethylene / high density polyethylene, various polyethylene / thermoplastic polyester, polypropylene / thermoplastic polyester, binary or terpolymer of propylene and other α-olefins / Thermoplastic polyester, various polyethylene / nylon 6, polypropylene / nylon 6, binary copolymers of propylene and other α-olefins, or terpolymers / nylon 6, nylon 6 / nylon 66, nylon 6 / Thermoplastic polyester That. Examples of the composite form include a sheath core type, an eccentric sheath core type, and a parallel type.

  It is also preferable to use two or more mixed fiber fibers having different melting points as the thermoplastic fiber constituting the nonwoven fiber assembly. The mixed fiber is a fiber formed by mixing the fiber made of the high melting point resin and the fiber made of the low melting point resin independently. The mixing ratio of the fiber made of the high melting point resin and the fiber made of the low melting point resin is the same as that of the above-mentioned composite fiber, and the same combination can be mentioned.

  The above-mentioned composite fiber and mixed fiber may be blended with other additives that impart functionality to the fiber or filter as long as the effects of the present invention are not hindered. Examples of the additive include an antibacterial agent, a deodorant, an antistatic agent, a smoothing agent, a hydrophilic agent, a water repellent, an antioxidant and a weathering agent. In addition, the surface of the composite fiber and the mixed fiber may be treated with a functional material, thereby imparting functions such as hydrophilicity, water repellency, antistatic, surface smoothness, and abrasion resistance. it can. Since the present invention is particularly useful as a liquid filter, it is preferably firmly fixed by, for example, chemical bonding so as not to be detached in the liquid.

  The nonwoven fiber assembly used in the present invention is preferably composed of one or a combination of two or more selected from the group consisting of tangled short fibers, meltblown nonwoven fabrics, and spunbond nonwoven fabrics. Any of them can be produced according to a known method. The nonwoven fiber assembly is preferably formed by superimposing one or more of these. The number of superpositions may be appropriately selected according to the thickness of the tangled short fibers, melt blown nonwoven fabric, or spunbond nonwoven fabric used and the thickness of the desired aggregate (filter material). About 5 to 15 sheets, and more preferably. It is also preferable to use a combination of different types. For example, it is preferable to have a configuration in which a spunbond nonwoven fabric is disposed on the uppermost layer and the lowermost layer in which a plurality of nonwoven fabrics or webs made of entangled short fibers are overlapped. The nonwoven fabrics and webs may be separated one by one, but the effect of the present invention can be further enhanced by bonding some or all of the nonwoven fabrics or webs in a later step.

  The pleated filter of the present invention is roughly prepared by (1) producing a nonwoven fiber assembly made of thermoplastic fibers having a thickness of 3 mm or more, (2) fold-folding the nonwoven fiber assembly, (3 ) The non-woven fiber assembly folded in the above process is wound around a cylindrical core, and both ends along the axial direction of the core of the non-woven fiber assembly are joined together to form an endless filter material in the circumferential direction. (4) A cap is attached to both ends, and (5) manufactured by a manufacturing method including a step of applying a temperature equal to or higher than at least one melting temperature of the thermoplastic fibers to the cylindrical filter obtained in the step. Is done.

  The production of the non-woven fiber assembly having a thickness of 3 mm or more made of (1) thermoplastic fiber can be performed by a conventionally known method. That is, for example, a parallel type composite short fiber is spun from two kinds of thermoplastic resins, and a web is produced by entanglement with a card machine, and a spunbond nonwoven fabric is laminated on both end layers obtained by laminating a plurality of webs. A nonwoven fiber assembly can be obtained. Further, for example, a sheath-core type composite fiber can be spun from two types of thermoplastic resins as raw materials, a melt blown nonwoven fabric can be subsequently produced, and a plurality of melt blown nonwoven fabrics can be overlapped to obtain a nonwoven fiber assembly.

  The sheet-like nonwoven fiber assembly obtained in (1) is subjected to step (2) fold folding. The fold folding process can be performed by appropriately selecting a conventionally known method. In addition, processes, such as cutting, shaping | molding, drying, and compaction, can be performed between process (1) and (2) as needed.

  Subsequently, in the step (3), the folded nonwoven fiber aggregate obtained in (2) is wound around a cylindrical core so as to have a predetermined number of ridges or a predetermined surface area. The ends of the aggregate filter in the axial direction are joined together to form a cylindrical filter material endless in the circumferential direction. The bonding method may be appropriately selected from known methods such as heat sealing and bonding using ultrasonic welding. A conventionally known core can be used as the cylindrical core, and for example, a porous cylindrical filter made of polyolefin resin can be used.

  Subsequently, (4) a cap is attached to both ends of the core around which the filter material is wound to form a cylindrical filter. The cap can also be attached by appropriately selecting a known method.

  Subsequently, in order to fuse the filter material, (5) at least one melting temperature of the thermoplastic fibers constituting the non-woven fiber aggregate of the filter material is applied. The heating can be performed in an oven, for example, and the heating time can be about 15 minutes to 30 minutes. The heating temperature may be appropriately selected at a temperature at which the low melting point resin component melts and the high melting point resin does not melt among the thermoplastic resin constituting the filter material.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited by them.
The measurement methods and definitions of the physical property values shown in the examples are as follows.
<Average fiber diameter of single fiber>
From the cross section of the fiber taken with an electron microscope, 100 lengths (diameters) in the direction perpendicular to the length direction of the fibers were measured, and the arithmetic average value was taken as the average fiber diameter. This calculation was performed using the image processing software “Scion Image” of Scion Corporation.
<Compression rate>
The filter material was cut into 20 mm × 20 mm, and the original thickness was measured. The thickness of the small piece when a load of 0.5 MPa was applied to the small piece was measured.
(Initial thickness−thickness when a load is applied) ÷ (initial thickness) = compression ratio was calculated as compression ratio.
<Filtration accuracy>
A filter is attached to the housing of the circulation type filtration performance tester, and water is circulated by a pump from a 50 liter water tank. After adjusting the flow rate to 30 liters per minute, 7 kinds of JIS powders, which are standard powders for basic physical properties, were continuously added as test powders in the water tank at 0.2 g per minute, and the stock solution and filtrate were added 5 minutes after the start of addition. The number of particles contained in the stock solution (A) is measured using a light blocking particle detector, and compared with the number of particles collected by the filter for each particle size (B). = The value calculated by (B / A × 100%) was defined as the collection efficiency. The value was analyzed, and the particle size at which the collection efficiency was 99.9% was defined as the filtration accuracy.
<Pressure loss>
In the circulation type filtration accuracy test, water is circulated at a flow rate of 30 liters per minute without adding powder. One minute after the start of circulation, the pressure loss (MPa) was measured.
<Filtration life (water)>
A filter is attached to the housing of the circulation type filtration performance tester, and water is circulated by a pump from a 50 liter water tank. After adjusting the flow rate to 30 liters per minute, 7 kinds of JIS powders, which are standard powders for basic physical properties, were continuously added as test powders in the water tank at 0.5 g per minute, and the differential pressure before and after the filter was 0.3 MPa. This was continued until the filtration life (water) was measured.
<Filtration life (glycerin)>
Glycerol was diluted with water to give a viscosity of 100 mPa · s (25 ° C.), and this was replaced with water, and the filtration life (glycerin) was measured in the same manner as described above.
<Pressure resistance>
A filter is attached to the housing of the circulation type filtration performance tester, and water is circulated by a pump from a 50 liter water tank. After adjusting the flow rate to 30 liters per minute, seven kinds of JIS powders, which are standard powders for basic physical properties, are continuously added as test powders in a water tank at 0.5 g per minute to increase the pressure. The pressure when the filter breaks was defined as the pressure resistance.
<Surface area>
The total area of the side surface of the wetted part of the outer periphery of the filter was defined as the surface area of the filter.

[Example 1]
High-density polyethylene (melting point: 137 ° C.) and polypropylene (melting point: 168 ° C.) were spun at a composite ratio of 50/50 using a parallel die at 280 ° C., and parallel composite fibers were spun. The obtained undrawn yarn was drawn 4 times at 110 ° C., subjected to mechanical crimping, and cut into a predetermined length to obtain short fibers. This short fiber was a side-by-side composite fiber having an apparent number of crimps of about 15/25 mm, a cut length of 51 mm, and a fiber diameter of about 50 μm.
The obtained parallel type composite fiber was made into a web having a basis weight of 30 g / m ² by a card machine. 25 sheets of this were stacked, and a spunbonded nonwoven fabric having a basis weight of 40 g / m ² and a thickness of 0.27 mm was stacked on the top and bottom, cut into 240 mm width, and pleated with a folding width of 13 mm. 15 rolls were wound around the cylindrical core, the ends of the sheet were heat-sealed, and then a cap made by injection molding was bonded to both ends of the cylindrical shape.
Then, it heated for 30 minutes in 135 degreeC oven, and produced the pleated filter of inner diameter 30mm, outer diameter 68mm, and length 250mm. At this time, the nonwoven fiber assembly had a thickness of 3 mm, a peak height of 13 mm, and a basis weight of 830 g / m ² .
The compressibility, filtration accuracy, pressure loss, filtration life (water), pressure resistance, surface area, and filtration life (glycerin) were measured for the pleated filter. The results are shown in Tables 1 and 2.

[Comparative Example 1]
A pleated filter was obtained by processing in the same process as in Example 1 except that polypropylene (melting point: 168 ° C.) was stretched twice at 290 ° C. using a single die at 80 ° C. The thickness of the nonwoven fiber assembly at this time was 3 mm, and the height of the mountain was 13 mm. The compressibility, filtration accuracy, pressure loss, filtration life (water), pressure resistance, surface area, and filtration life (glycerin) were measured for the pleated filter. The results are shown in Tables 1 and 2.
Although the pleated filter of Comparative Example 1 had the same pressure loss as that of Example 1, the filtration accuracy was high and the pressure resistance was low.

[Comparative Example 2]
A web was prepared in the same manner as in Example 1, and one web was used without overlapping, and a spunbonded nonwoven fabric having a basis weight of 40 g / m ² and a thickness of 0.27 mm was superimposed on the top and bottom, and the same method as in Example 1 was used. Created a pleated filter. The number of mountains was 100. The thickness of the nonwoven fiber assembly at this time was 1 mm, and the height of the mountain was 13 mm. The compressibility, filtration accuracy, pressure loss, filtration life (water), pressure resistance, surface area, and filtration life (glycerin) were measured for the pleated filter. The results are shown in Tables 1 and 2.
Compared with Example 1, the pleated filter of Comparative Example 2 had a short filtration life and a low pressure resistance despite the same filtration accuracy.

[Comparative Example 3]
A web was prepared in the same manner as in Example 1, heated at 135 ° C. and immediately wound around an iron core, and wound until the outer diameter reached 68 mm. Thereafter, the iron core was removed to obtain a depth filter. For the depth filter, the compression rate, filtration accuracy, pressure loss, filtration life (water), pressure resistance, surface area, and filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.
Compared with Example 1, the pleated filter of Comparative Example 3 had a short filtration life and a low pressure resistance despite the same filtration accuracy.

[Example 2]
MFR (test condition 230 ° C., 2.16 kg) is 280 g / 10 min as the core component, and polypropylene having a melting point of 164 ° C. is used, and MFR (test condition 190 ° C., 2.16 kg) is 124 g / 10 as the sheath component. And a PP copolymer having a melting point of 122 ° C., spinning temperatures of 290 ° C. and 260 ° C., respectively, both components having a core-sheath composite ratio of 50/50, a total discharge amount of 120 g / min, a pore diameter of 0.3 mm, The melt-blown sheath-core type composite spinneret having 501 holes arranged in a row was supplied and extruded.
Furthermore, the polymer extruded from the spinneret was sprayed onto a net conveyor using pressurized air at 380 ° C. to obtain an ultrafine composite fiber web of a melt blow method having a basis weight of 50 g / m ² .
This was processed in the same process as in Example 1 to obtain a pleated filter. At this time, the nonwoven fabric aggregate had a thickness of 3 mm, a peak height of 13 mm, and a basis weight of 1330 g / m ² .
About the obtained pleated filter, the compression rate, the filtration accuracy, the pressure loss, the filtration life (water), the pressure resistance, the surface area, and the filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.

[Example 3]
Mixed fiber spinning was performed using two extruders and a mixed fiber melt blow apparatus having a melt blow spinneret having a hole diameter of 0.3 mm and a hole number of 501 as main components. The die is a die having a structure in which two types of molten resin extruded from two extruders are not mixed in each hole and the first component and the second component are discharged for each hole. ing.
As the first component, an MFR (test condition 190 ° C., 2.16 kg) is 120, a PP copolymer having a melting point of 121 ° C. is used, and as the second component, MFR (test condition 30 ° C., 2.16 kg) is 120. A fiber having a melting point of 164 ° C., a spinning temperature of 260 ° C. of the first component and a constant of 280 ° C. of the second component, melt extrusion from the mixed fiber melt blow apparatus (melt blow spinning), and fibers discharged from the spinning holes The air at a temperature of 360 ° C. was pressurized to a pressure of 0.12 MPaG and sprayed onto a conveyor net equipped with a jet gas suction device to obtain a melt blown ultrafine fiber web.
This was processed in the same process as in Example 1 to obtain a pleated filter. At this time, the nonwoven fiber assembly had a thickness of 3 mm, a peak height of 13 mm, and a basis weight of 830 g / m ² .
About the obtained pleated filter, the compression rate, the filtration accuracy, the pressure loss, the filtration life (water), the pressure resistance, the surface area, and the filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.

[Comparative Example 4]
Polypropylene having an MFR (test conditions of 230 ° C., 2.16 kg) of 180 g / 10 min, a melting point of 164 ° C., a spinning temperature of 280 ° C., a discharge rate of 120 g / min, a pore diameter of 0.3 mm, a number of holes 501 spinnerets were supplied to a meltblown spinneret in a line and extruded.
The polymer extruded from the spinneret was sprayed onto a net conveyor using pressurized air at 380 ° C. to obtain a melt blown ultrafine fiber web.
This was processed in the same process as in Example 2 to obtain a pleated filter. The thickness of the nonwoven fiber assembly at this time was 3 mm, and the height of the mountain was 13 mm.
About the obtained pleated filter, the compression rate, the filtration accuracy, the pressure loss, the filtration life (water), the pressure resistance, the surface area, and the filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.
The pleated filter of Comparative Example 4 was higher in filtration accuracy and lower in pressure resistance than Example 2. Moreover, compared with Example 3, the filtration accuracy was large and the pressure resistance was low.

[Example 4]
A spunbond nonwoven fabric made of polypropylene was manufactured using a composite spunbond spinning device equipped with a composite spinning machine, air soccer, net conveyor, and the like, and a net conveyor. The base used was a sheath core type composite spinneret with a hole diameter of 0.4 mm. High-density polyethylene having a melting point of 133 ° C. as the first component and MFR (test conditions of 190 ° C., 2.16 kg) of 22 g / 10 min is used on the sheath side, and a melting point of 164 ° C. as the second component, Polypropylene with an MFR (test conditions 230 ° C., 2.16 kg) of 60 g / 10 min is used on the core side, the composite ratio is 50/50 (weight%), the spinning temperature of the first component is 290 ° C., and the second component Spinning was carried out at a spinning temperature of 310 ° C., fibers were sucked with air soccer at a speed of 3,000 m / min, and the fibers were blown onto a net conveyor together with air.
The obtained fiber was a sheath-core long fiber having a fiber diameter of 14 μm. The basis weight of the obtained spunbonded nonwoven fabric was 30 g / m ² . The air blown was removed by suction with a suction device provided at the lower part of the net conveyor.
25 sheets were stacked and processed in the same process as in Example 1 to obtain a pleated filter. At this time, the nonwoven fiber assembly had a thickness of 3 mm, a peak height of 13 mm, and a basis weight of 830 g / m ² .
About the obtained pleated filter, the compression rate, the filtration accuracy, the pressure loss, the filtration life (water), the pressure resistance, the surface area, and the filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.

[Comparative Example 5]
A web was obtained in the same manner as in Example 4 except that only polypropylene having a melting point of 164 ° C. and an MFR (test conditions of 230 ° C., 2.16 kg) of 60 g / 10 min was used. The obtained fiber was a long fiber having a fiber diameter of 14 μm. The basis weight was 30 g / m ² .
This was processed in the same process as in Example 4 to obtain a filter. The thickness of the nonwoven fiber assembly at this time was 3 mm, and the height of the mountain was 13 mm.
About the obtained pleated filter, the compression rate, the filtration accuracy, the pressure loss, the filtration life (water), the pressure resistance, the surface area, and the filtration life (glycerin) were measured. The results are shown in Tables 1 and 2.
The pleated filter of Comparative Example 5 was higher in filtration accuracy and lower in pressure resistance than Example 4.

  The pleated filter of the present invention has a long filtration life with respect to a high-viscosity fluid and not only has excellent pressure resistance, but also has high filtration accuracy, so it can be used for general filter applications. It can be suitably used for applications such as filtration of highly viscous liquids such as agents.

Claims (9)

A cylindrical pleated filter, wherein the filter material of the pleated filter is a fold-folded non-woven fiber assembly made of thermoplastic fibers and having a thickness of 3 mm or more, and the filter material is subjected to a load of 0.5 MPa A pleated filter having a compression ratio of 0.2 or less. It is a cylindrical pleated filter, and the filter material of the pleated filter is a folded woven nonwoven fiber assembly having a thickness of 3 mm or more made of thermoplastic fiber, and the nonwoven fiber assembly is fused at the fiber intersection. A pleated filter. The pleated filter according to claim 1 or 2, wherein the thermoplastic fiber is a composite fiber composed of two or more components having different melting points. The pleated filter according to claim 1 or 2, wherein the thermoplastic fiber is a mixed fiber of two or more components having different melting points. The pleated filter according to any one of claims 1 to 4, wherein an outer diameter of the pleated filter is 50 to 80 mm. The pleated filter according to any one of claims 1 to 5, wherein a height of a pleat peak is 7 to 20 mm. The nonwoven fabric aggregate is composed of one or a combination of two or more selected from the group consisting of tangled short fibers, meltblown nonwoven fabrics, and spunbond nonwoven fabrics. The pleated filter described in 1. The nonwoven fiber assembly has a web composed of at least one layer of parallel type composite fibers, and a spunbond nonwoven fabric laminated on both surfaces of the web, and the web and the spunbond nonwoven fabric are integrated. The pleated filter according to claim 7. (1) producing a non-woven fiber assembly having a thickness of 3 mm or more made of thermoplastic fibers;
(2) fold-folding the non-woven fiber assembly;
(3) The non-woven fiber assembly folded in the above-described step is wound around a cylindrical core, and both ends along the axial direction of the core of the non-woven fiber assembly are combined to make a filter endless in the circumferential direction The process of making the material,
(4) attaching a cap to both ends of the core around which the filter material is wound to form a cylindrical filter;
(5) including, to the cylindrical filter obtained in the step (4), a step of applying a temperature equal to or higher than at least one melting temperature of the thermoplastic fibers.
Pleated filter manufacturing method.