JP2008018430A - Cylindrical filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical filter having a long filtration life. <P>SOLUTION: The cylindrical filter of the present invention is manufactured from main filtration nonwoven fabric comprising two or more kinds of resin components, containing two or more kinds of ultrafine fibers derived from splittable fibers splittable by an external force, and substantially not fibllated fibers with a fiber diameter of less than 20μm. The fiber includes ultrafine fibers of a fiber diameter of 4μm or less and bonded adhesive fiber of a fiber diameter of 8-20μm. The cylindrical filter includes auxiliary filtration nonwoven fabric consisting of wet nonwoven fabric with a maximum hole diameter twice or less of the average flow rate hole diameter, and with an average flow pore diameter larger than the main filtration nonwoven fabric. The main filtration nonwoven fabric and auxiliary filtration nonwoven fabric are disposed around the porous cylinder in an adjacently layered state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylindrical filter that can filter solids in a fluid, and more particularly to a cylindrical filter that can filter solids in a liquid.

  Conventionally, a so-called pleated filter in which a folded filter material is arranged around a perforated tube is known as a filter that can filter solids in a liquid. This pleated filter is suitable because it has a large filtration area and a long filtration life. As a filtering material constituting this pleated filter, a nonwoven fabric obtained by pressurizing a melt blown nonwoven fabric with a heat calender roll is known. Since this filter medium has a fine pore diameter, a desired filtration efficiency can be obtained, but there is a problem that clogging is likely to occur due to poor fluid permeability and the filtration life is short. Moreover, the filter medium which laminated | stacked the net | network on the melt blown nonwoven fabric is known. In some cases, the filter material in which the net is laminated damages the filter medium (the one obtained by pressurizing the melt blown nonwoven fabric). Moreover, since the net hardly contributes to filtration, it was not fully satisfactory in terms of filtration life. In addition, a fiber sheet containing a split type composite fiber having poly 4-methylpentene-1 as a first component and a polyolefin polymer as a second component is manufactured by a wet papermaking method, and subjected to high-pressure water flow treatment to be split. The composite fiber is divided to form ultrafine fibers, and at the same time, a nonwoven fabric in which the fibers are entangled with each other is used as a filtering material, or an ethylene-vinyl alcohol copolymer is used as a first component, and a polyolefin polymer is used as a first component. A fiber sheet containing a split composite fiber as a two-component was manufactured by a wet papermaking method, and this was subjected to a high-pressure water flow treatment to split the split composite fiber to form ultrafine fibers and simultaneously entangle the fibers. Then, what uses the nonwoven fabric which performed the heat-pressing process in the wet condition, and adhere | attached fibers as a filter medium is known. When these filter media are used as filter media constituting a pleated filter, the range of the size distribution of the inter-fiber voids of the filter media itself is narrow and the filtration accuracy is excellent, but the surfaces of the filter media are in close contact with each other. In addition to the possibility of reducing the filtration area, there is a drawback that the filtration life is shortened because the back surfaces of the filtration media may be in close contact with each other to reduce the filtration area. In order to eliminate such drawbacks, it is also known that the material is creased together with a reinforcing material such as a spunbond nonwoven fabric or a net-like sheet. Although the reduction of the area can be prevented, the filter medium may be damaged by the net. Moreover, even if reinforced with a spunbond nonwoven fabric or a net, the level of filtration life was not sufficiently satisfactory. Such a problem may also be found in the case of a so-called depth filter in which a filter medium is wound in a flat shape around a porous cylinder.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a cylindrical filter having a long filtration life.

The second cylindrical filter of the present invention (hereinafter referred to as “second cylindrical filter”) is composed of two or more types of resin components, and includes two or more types of ultrafine fibers generated from splittable fibers that can be divided by an external force. The main filtration non-woven fabric and the fibers are produced from fibers that are substantially non-fibrillated and have a fiber diameter of less than 20 μm. As the fibers, ultrafine fibers having a fiber diameter of 4 μm or less, and fiber diameters of 8 μm or more and less than 20 μm. And an auxiliary filtration nonwoven fabric made of a wet nonwoven fabric having a maximum pore diameter of not more than twice the average flow pore diameter and an average flow pore diameter larger than that of the main filtration nonwoven fabric, and the main filtration nonwoven fabric, The auxiliary filtering nonwoven fabric is disposed around the perforated cylinder in a state where the auxiliary filtering nonwoven fabric is laminated adjacently. As a result of intensive research, the inventors of the present invention have a dense structure of a main filtration nonwoven fabric comprising two or more types of resin components and including two or more types of ultrafine fibers generated from splittable fibers that can be split by external force. Nevertheless, it has the characteristics that the filtration flow rate is large, the filtration accuracy is excellent, and the filtration life is also long, and such a specific main filtration nonwoven fabric has a larger average flow pore size than this main filtration nonwoven fabric. It has been found that the filter life is further increased when the auxiliary filtration nonwoven fabric made of the above wet nonwoven fabric is combined. Moreover, since the above auxiliary filtration nonwoven fabric is excellent also in the intensity | strength adhere | attached with the adhesive fiber, it can also manufacture a cylindrical filter with sufficient workability (for example, foldability, winding property). I found it. Furthermore, the tubular filter with a particular primary filtration nonwoven combining a specific supplemental filtration nonwovens such as, without impairing the filtration area, the filtration life is long, there is since also found to have excellent filtration accuracy .

  The tubular filter of the present invention has a long filtration life, excellent filtration performance, and excellent workability (for example, fold-folding workability and winding property).

  The main filtration nonwoven fabric which comprises the 1st cylindrical filter of this invention, the 2nd cylindrical filter, and the 3rd cylindrical filter were all formed from the splittable fiber which consists of two or more types of resin components, and can be divided by external force. It consists of a nonwoven fabric containing two or more types of ultrafine fibers. Therefore, despite having a dense structure, the filtration flow rate is large, the filtration accuracy is excellent, and the filtration life is long. The two or more types of ultrafine fibers constituting the main filtration nonwoven fabric are formed of splittable fibers that are composed of two or more types of resin components and can be divided by an external force. This splittable fiber consists of two or more types of resin components so that two or more types of ultrafine fibers can be generated. Examples of the resin component constituting the splittable fiber include polyamide resins (for example, nylon 6, nylon 66, etc.), polyester resins (for example, polyethylene terephthalate, polybutylene terephthalate, etc.), polyvinylidene chloride resins, or Polyolefin resin (for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, ethylene copolymer, polypropylene, propylene copolymer, polymethylpentene, methylpentene copolymer, etc.) Can be mentioned. Among these, it is preferable to include a polyolefin resin excellent in chemical resistance, and it is more preferable that the resin is composed of only a polyolefin resin (for example, a propylene resin and an ethylene resin). It is preferable that the resin component as described above is disposed so that the splittable fiber can be split by an external force. More specifically, the cross-sectional shape of the splittable fiber is preferably, for example, an orange type as shown in FIGS. 1 to 4 or a multiple bimetal type as shown in FIG. Examples of the external force that can split the splittable fiber include a fluid flow such as a water flow, a needle, a calendar, and a flat press. Among these, it is preferable that the fluid flow not only divides but also entangles the fibers. Such splittable fibers can be produced by a conventional melt spinning method.

  The main filtration nonwoven fabric of the present invention contains two or more types of ultrafine fibers generated from the splitting fibers as described above. Therefore, the number of types of ultrafine fibers coincides with the number of resin components constituting the aforementioned splittable fibers. The cross-sectional shape of the ultrafine fiber varies depending on the arrangement state of the resin component constituting the splittable fiber in the fiber cross-section, and when the cross-sectional shape of the splittable fiber is orange as shown in FIG. When the shape is composed of only ultrafine fibers in the shape of orange, as shown in FIG. 2, the shape is composed of a substantially triangular shape of ultrafine fibers and a substantially elliptical shape of fine fibers, and when the shape is orange as shown in FIG. 4. It is composed of a substantially triangular ultrafine fiber and a substantially circular ultrafine fiber, and in the case of the orange type as shown in FIG. 4, it is composed of a substantially triangular ultrafine fiber, a substantially circular ultrafine fiber, and a substantially elliptical ultrafine fiber. Thus, in the case of the multiple bimetal type as shown in FIG. 5, it is composed only of super-fine fibers having a substantially alphabetic eye (I) shape. The “ultrafine fiber” in the main filtration nonwoven fabric of the present invention means a fiber having a fiber diameter of 5 μm or less, and more preferably 4 μm or less. The lower limit is not particularly limited, but about 0.01 μm is appropriate. The “fiber diameter” in the present invention refers to the diameter when the fiber cross-sectional shape is circular, and refers to the diameter when converted into a circular cross-section when the fiber cross-sectional shape is non-circular.

  Although the main filtration nonwoven fabric of this invention contains the above ultrafine fibers, it can contain the non-dividing | segmented fiber which became the source of the ultrafine fibers other than an ultrafine fiber. By including such splittable fibers, it is possible to impart an appropriate strength to the main filtration nonwoven fabric, and as a result, a main filtration nonwoven fabric having excellent processability can be obtained. It is preferable that such non-divided split fibers are unevenly distributed in the thickness direction of the main filtration nonwoven fabric. In this case, the main filtration nonwoven fabric is formed with dense regions (regions containing ultrafine fibers) and relatively coarse regions (regions containing splittable fibers) in the thickness direction. The effect is that the lifetime is long and the filtration performance is further excellent.

  When the main filtration nonwoven fabric of the present invention further contains a fusible fiber, the fusible fiber can be fused, thereby imparting an appropriate strength to the main filtration nonwoven fabric. The main filtration nonwoven fabric can be made excellent. The fiber diameter of the fusible fiber is preferably 0.5 to 25 μm and more preferably 1 to 20 μm so as not to impair the filtration performance by the ultrafine fiber. The fusible fiber may be composed of a single component, but is preferably composed of two or more types of resin components so that the fiber form can be maintained even after the fusion. When composed of two or more types of resin components, the fiber cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, a multiple bimetal type, or the like. Among these, a core-sheath type, an eccentric type, or a sea-island type with a large amount of resin (fusion component) that can participate in fusion is preferable. This fusible fiber can be composed of the same resin component as that constituting the ultrafine fiber, but the meltable fiber of the fusible fiber is melted so that the ultrafine fiber is not melted to impair the filtration performance of the ultrafine fiber. The melting point of the landing component is preferably 10 ° C. or more lower than the melting point of the ultrafine fiber having the lowest melting point, more preferably 20 ° C. or more. Further, when the fusible fiber is composed of two or more kinds of resin components, other than the fusible component so that the fiber shape of the fusible fiber can be maintained by heat when fusing the fusible fiber. The melting point of the resin component (non-adhesive component) is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, than the melting point of the fusion component. The “melting point” in the present invention refers to a temperature that gives a maximum value of a melting endothermic curve obtained by using a differential scanning calorimeter at a temperature rising temperature of 10 ° C./min and raising the temperature from room temperature. When there are two or more maximum values, the highest temperature maximum value is taken as the melting point.

  When the main filtration nonwoven fabric of the present invention further contains hydrophilic fibers, it is possible to impart hydrophilicity to the main filtration nonwoven fabric, and as a result, a main filtration nonwoven fabric having excellent hydrophilicity can be obtained. Thus, when the main filtration nonwoven fabric is excellent in hydrophilicity, when the processing fluid is water, the water permeability in the main filtration nonwoven fabric, that is, the filtration flow rate can be improved, and the filtration life can be improved. Further, in the case of a filtration method using a pressure pump, it is possible to reduce the pressure energy and the load due to the pressure applied to the filter medium. This “hydrophilic fiber” refers to a fiber having an official moisture content of 4% or more, such as rayon fiber, polynosic fiber, cupra fiber, acetate fiber, tencel fiber (cellulose fiber obtained by solvent extraction method), and the like. Can do.

The surface density of the main filtration nonwoven fabric of the present invention is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is 0.05 to 0.7 g / m ^2. It is preferably about cm ³ . Furthermore, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, and more preferably about 0.5 to 20 μm. The “average flow pore size” in the present invention refers to a value obtained by a method defined in ASTM-F316, and is measured by a mean flow point method using, for example, a porometer (Polometer, manufactured by Coulter). Value.

  Such a main filtration nonwoven fabric can be manufactured as follows, for example. First, a splittable fiber composed of two or more types of resin components and splittable by an external force is prepared. If necessary, a fusible fiber is prepared. Subsequently, a fiber web containing splittable fibers is formed by a dry method (for example, a card method, an air lay method, a spun bond method, a melt blow method, etc.) or a wet method. In addition, after forming a fiber web, you may laminate | stack different or the same kind of fiber web. For example, the main filtration nonwoven fabric which has a dense area | region and a comparatively rough area | region in the thickness direction can be manufactured by laminating | stacking the fiber web from which the compounding ratio of a splittable fiber differs. Subsequently, by applying a fluid flow such as a water flow to the fiber web, the split fiber can be split to generate ultra fine fibers and simultaneously entangle the ultra fine fibers to produce a main filtration nonwoven fabric. . The processing conditions by the fluid flow applicable in the present invention include, for example, a pressure of 1 MPa to 30 MPa from a nozzle plate having nozzle diameters of 0.05 to 0.3 mm and pitches of 0.2 to 3 mm and nozzles arranged in one or more rows. It is sufficient to eject the fluid flow. Such a fluid flow is ejected at least once on one or both sides of the fiber web. When the non-perforated portion of the support such as a net or perforated plate on which the fiber web is placed when processing with the fluid flow is thick, the obtained main filtration nonwoven fabric also has large pores, resulting in poor filtration accuracy. For this reason, it is preferable to use a support having a non-perforated portion having a thickness of 0.25 mm or less. In addition, when the splittable fiber is composed of only the same kind of resin component (for example, made of only a polyolefin resin) and is difficult to split (for example, when a fiber web is formed by a wet method), the splittable fiber is configured. These methods can be used by applying a fluid flow after fusing the resin component, mixing a fusible fiber in the fiber web, and applying a fluid flow after fusing the fusible fiber. When used in combination, it can be easily divided. In this case, the splitting action of splittable fibers occurs preferentially, and the entanglement of ultrafine fibers does not occur much. Therefore, in order to give strength to the main filtration nonwoven fabric, it is preferable to fuse the resin component and / or the fusible fiber constituting the splittable fiber again. Further, as described above, the main filtration nonwoven fabric including the splitting fibers that are not divided, for example, reduces the pressure of the fluid flow, reduces the number of times the fluid flow is applied, or sets the direction in which the fluid flow is applied. The resin component and / or the fusible fiber constituting the splittable fiber can be fused and fixed before the fluid flow is applied, or these methods can be used in combination. The above description is about a method of producing a main filtration nonwoven fabric by applying a fluid flow to the fiber web and simultaneously dividing the split fiber. (1) The main filter nonwoven fabric is formed by a needle and the split fiber is simultaneously formed. (2) Before forming the fiber web, at least one external force such as a fluid flow, a needle, a calendar, a flat press, etc. is applied to form the fiber web after dividing the splittable fiber, Next, it may be entangled with a fluid flow or a needle, or may be fused with a fusible fiber by containing a fusible fiber, or may be bonded with a binder. (3) After the fiber web is bonded The main filtration nonwoven fabric of the present invention can also be produced by dividing the splittable fiber by applying at least one external force of fluid flow, needle, calendar, and flat press.

  The first tubular filter of the present invention has an auxiliary filtration nonwoven fabric (hereinafter referred to as the first auxiliary filtration nonwoven fabric) having a mean flow pore size larger than that of the main filtration nonwoven fabric as described above and comprising a mixed nonwoven fabric in which meltblown fibers and thermoplastic stretched fibers are mixed. Is included). In the present invention, the filter life can be extended by filtering a large solid with the first auxiliary filtration nonwoven fabric and reducing the load on the main filtration nonwoven fabric. Moreover, adhesion of main filtration nonwoven fabrics can be suppressed by the first auxiliary filtration nonwoven fabric, and the filtration performance of the main filtration nonwoven fabric can be sufficiently exhibited. The average fiber diameter of the meltblown fibers (average fiber diameter at 100 or more points) is preferably from 0.1 to 20 μm, and more preferably from 0.1 to 10 μm. Further, such melt blown fibers are preferably contained in the first auxiliary filtration nonwoven fabric in an amount of 5 to 95 mass%, and more preferably in an amount of 15 to 85 mass%. The conditions for producing the meltblown fiber are not particularly limited, but can be produced, for example, under the following conditions. Nozzle pieces having orifice diameters of 0.1 to 0.5 mm and pitches of 0.3 to 1.2 mm are heated to a temperature of 220 to 370 ° C., and 0.02 to 1.5 g / min per orifice. Resin is discharged at a rate, and a melt blown fiber can be produced by applying a gas having a temperature of 220 to 400 ° C. and a mass ratio of 5 to 2,000 times the resin discharge amount. it can. Examples of the resin component constituting the melt blown fiber include polyester resins, polyamide resins, polyolefin resins (eg, polyethylene resins, polypropylene resins, etc.), polyvinylidene chloride resins, polyvinyl chloride resins, polystyrene. It can be composed of at least one type of resin such as a resin, a polyacrylonitrile resin, and a polyvinyl alcohol resin. Among these resins, polyolefin resins (particularly polypropylene) can be suitably used because they are excellent in chemical resistance and versatility. In addition, the resin component which comprises a meltblown fiber does not need to be 1 type, and may be comprised from 2 or more types. When the meltblown fiber is composed of two or more kinds of resins, the cross-sectional shape of the fiber can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multiple bimetal type.

On the other hand, "thermoplastic drawn fiber" is not a fiber drawn by applying air to the fiber extruded from the nozzle, such as a melt blown fiber or a spunbond fiber, but a fiber extruded from the nozzle, such as a drawing machine. A fiber drawn by mechanical action. The average fiber diameter of the thermoplastic stretched fiber is preferably 10 to 100 μm, and more preferably 15 to 80 μm. Moreover, it is preferable that 5-95 mass% is contained in such a 1st auxiliary | assistant filtration nonwoven fabric, and, as for such a thermoplastic stretch fiber, it is more preferable that 15-85 mass% is contained. In addition, the average fiber diameter of the thermoplastic stretched fiber refers to the average value of the fiber diameters at 100 or more points when the thermoplastic stretched fiber is a long fiber, and when the thermoplastic stretched fiber is a short fiber. Means the average value of the fiber diameters of 100 or more thermoplastic stretched fibers. This thermoplastic drawn fiber can be composed of one or more kinds of resins similar to those constituting the melt blown fiber as described above. When the thermoplastic stretched fiber is composed of two or more types of resin components, the cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multiple bimetal type. . As described above, when the thermoplastic stretched fiber is composed of two or more kinds of resin components, even if a resin component (adhesive component) that can be bonded is bonded, the fiber shape is maintained by the resin component (non-adhesive component) that is not bonded, Since a moderate space by the plastic stretched fiber can be maintained, it is excellent in fluid permeability. Thus, when a thermoplastic stretch fiber consists of two or more types of resin components, it is preferable that the melting | fusing point difference of an adhesive component and a non-adhesion component is 10 degreeC or more, and it is more preferable that it is 20 degreeC or more. The adhesive component of the thermoplastic stretched fiber is preferably 10 ° C. or more lower than the melting point of the meltblown fiber (if the meltblown fiber is made of two or more resins, the melting point of the resin having the lowest melting point), More preferably, it is lower. The thermoplastic drawn fibers may be long fibers or short fibers, but are preferably short fibers so that they can be present in a state of being uniformly mixed with meltblown fibers. In the case of a short fiber, the fiber length is preferably 5 to 160 mm, and more preferably 25 to 110 mm so as to be easily entangled with the meltblown fiber. This thermoplastic drawn fiber does not need to consist of one type, and two or more types of thermoplastic drawn fibers that differ in terms of fiber diameter, composition, fiber length, and the like may be mixed. Such a 1st auxiliary filtration nonwoven fabric can be manufactured as follows, for example. First, as shown in FIG. 6, with respect to the flow of the meltblown fiber 2 formed by the meltblown apparatus 1 under the conditions as described above, the thermoplastic stretched fiber 4 opened by the fiber spreader 3 is supplied to After mixing, the mixed fiber group can be collected by a collecting body 5 such as a conveyor to form the first auxiliary filtration nonwoven fabric 6. Examples of the opening machine 3 for supplying the thermoplastic stretched fiber 4 include a card machine and a garnet machine, and the opening machine 3 in which a plurality of opening cylinders 31 as shown in FIG. The thermoplastic stretched fibers 4 can collide with the flow of the meltblown fibers 2 vigorously, and the meltblown fibers 2 and the thermoplastic stretched fibers 4 can be mixed evenly in the thickness direction of the first auxiliary filtration nonwoven fabric 6. Therefore, it is preferable. Further, when the thermoplastic stretched fiber 4 is supplied by the fiber spreader 3, the thermoplastic stretched fiber 4 is thermoplastically stretched from a direction perpendicular to the flow of the meltblown fiber 2 so that the thermoplastic stretched fiber 4 can be uniformly mixed with the meltblown fiber 2. It is preferable to supply the fibers 4. For example, when the flow of the meltblown fiber 2 formed by the meltblown apparatus 1 is in the horizontal direction, the thermoplastic stretched fiber 4 may be naturally dropped and supplied from above in a direction perpendicular to the flow of the meltblown fiber 2. Although the flow direction of the meltblown fiber 2 formed by the meltblowing apparatus 1 is generally preferably the same as the direction in which gravity acts, the thermoplastic stretched fiber 4 supplied from the fiber opening machine 3 is in gravity. It is preferable to supply from a direction perpendicular to the direction of the movement. In the fiber opening machine 3 of FIG. 7, an air nozzle 33 capable of supplying air is provided so that the thermoplastic stretched fiber 4 can be supplied vigorously even at such an angle (right angle). In addition, the abundance ratio of the thermoplastic stretched fibers 4 in the thickness direction of the first auxiliary filtration nonwoven fabric 6 can be changed by adjusting the angle at which the thermoplastic stretched fibers 4 are supplied to the meltblown fibers 2. The collecting body 5 for collecting the fiber group in which the melt blown fiber 2 and the thermoplastic stretched fiber 4 are mixed may be in a roll shape or a conveyor shape. In order to prevent the first auxiliary filtration nonwoven fabric 6 from being disturbed or scattered by the collision with the airflow, the collector 5 is preferably breathable, and an airflow suction device is provided on the side opposite to the collection surface. Is preferred. The first auxiliary filtration nonwoven fabric 6 thus manufactured may be used as it is, but it is preferable to adjust the average flow pore size by performing a heat treatment and / or a pressure treatment. The heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment is performed. The heating temperature when the heat treatment and the pressure treatment are performed simultaneously is preferably 5 to 120 ° C. lower than the melting point of the adhesive component of the thermoplastic stretched fiber, and the linear pressure at this time is 0.1 to 4 kN. / cm is preferred. On the other hand, the heating temperature when the pressure treatment is carried out after the heat treatment is preferably 5 to 40 ° C. higher than the melting point of the adhesive component of the thermoplastic stretched fiber. It is preferably 1 to 4 kN / cm. In addition, when only heat processing is implemented, it is preferable that the heating temperature is 5-40 degreeC higher than melting | fusing point of the adhesive component of a thermoplastic stretched fiber. The surface density of the first auxiliary filtration nonwoven fabric of the present invention is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is 0.05 to 0.00. It is preferably about 7 g / cm ³ . The average flow pore size of the first auxiliary filtration nonwoven fabric in the first tubular filter is larger than the average flow pore size of the main filtration nonwoven fabric as described above. The degree thereof is appropriately changed depending on the fluid to be filtered, and is not particularly limited. However, it is preferably about 2 to 40 μm and more preferably about 2 to 20 μm larger than the main filtration nonwoven fabric. More specifically, as described above, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, more preferably about 0.5 to 20 μm. The average flow pore size is preferably 2.5 to 80 μm, more preferably 2.5 to 60 μm, still more preferably 2.5 to 40 μm.

In the second cylindrical filter of the present invention, the main filtration nonwoven fabric as described above and a fiber having a fiber diameter of less than 20 μm, which is not substantially fibrillated, are produced, and the fiber diameter is 4 μm. Including the following ultrafine fibers (hereinafter referred to as “auxiliary ultrafine fibers”) and bonded adhesive fibers having a fiber diameter of 8 μm or more and less than 20 μm, and the maximum pore diameter is not more than twice the average flow pore diameter, and the main filtration And an auxiliary filtration nonwoven fabric (hereinafter sometimes referred to as a second auxiliary filtration nonwoven fabric) made of a wet nonwoven fabric having an average flow pore size larger than that of the nonwoven fabric. This 2nd cylindrical filter can lengthen the filtration life by filtering a big solid with this 2nd auxiliary filtration nonwoven fabric, and reducing the load of the main filtration nonwoven fabric. Moreover, adhesion between the main filtration nonwoven fabrics can be suppressed by the second auxiliary filtration nonwoven fabric, and the filtration performance of the main filtration nonwoven fabric can be sufficiently exhibited. This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is manufactured from fibers that are not substantially fibrillated so as not to impair the uniform dispersibility of the fibers. This “non-fibrillated fiber” means a fiber in which a plurality of fibers are not bonded, for example, a fiber in which an infinite number of fibers branch from one fiber (for example, a fiber beaten by a beater, Pulp) or a fiber in which a plurality of fibers are already bonded and in a network state (for example, a fiber obtained by flash spinning). The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is a fiber having a fiber diameter of less than 20 μm (preferably, so as not to disturb the fiber arrangement due to the presence of thick fibers and to form a large aperture diameter). , Fibers having a fiber diameter of 18 μm or less). More specifically, it includes auxiliary fine fibers having a fiber diameter of 4 μm or less and bonded adhesive fibers having a fiber diameter of 8 μm or more and less than 20 μm. The fiber diameter is 4 μm or less and more preferably 3 μm or less so that the former auxiliary ultrafine fiber can be uniformly dispersed to form a uniform pore diameter. The lower limit of the fiber diameter of the auxiliary ultrafine fiber is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.3 μm or more, and further preferably 0.5 μm or more, Most preferably, it is 0.75 μm or more. It is preferable that the fiber diameters of the auxiliary ultrafine fibers are substantially the same so that a uniform pore diameter can be formed by the auxiliary ultrafine fibers as described above. That is, the value obtained by dividing the standard deviation value of the fiber diameter distribution of the auxiliary fine fibers by the average value of the fiber diameters of the auxiliary fine fibers is preferably 0.2 or less (preferably 0.18 or less). In addition, since the standard deviation value becomes 0 when the fiber diameters of the auxiliary fine fibers are all the same, the value obtained by dividing the standard deviation value of the fiber diameter distribution of the auxiliary fine fibers by the average value of the fiber diameters of the auxiliary fine fibers. The lower limit of is zero. The “average value of the fiber diameter” of the auxiliary ultrafine fibers is obtained by taking an electron micrograph of the second auxiliary filtration nonwoven fabric (wet nonwoven fabric), and the fiber diameter of 100 or more (n) auxiliary ultrafine fibers in the electron micrograph. Is the average value of the measured fiber diameters. The “standard deviation value” of the auxiliary ultrafine fiber is a value calculated from the measured fiber diameter (χ) by the following equation.
Standard deviation = {(nΣχ ² − (Σχ) ² ) / n (n−1)} ^1/2
Here, n means the number of auxiliary fine fibers measured, and χ means the fiber diameter of each auxiliary fine fiber. In addition, when there are two or more types of auxiliary ultrafine fibers having a fiber diameter of 4 μm or less, it is preferable that the above relationship is established for each auxiliary ultrafine fiber. In addition, it is preferable that the auxiliary ultrafine fibers have substantially the same diameter in the fiber axis direction of the auxiliary ultrafine fibers so that a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a uniform pore diameter can be formed. Such auxiliary fine fibers having substantially the same fiber diameter, or auxiliary fine fibers having substantially the same diameter in the fiber axis direction, for example, the island component by regulating the die in the sea component at the spinneret portion. It can be obtained by removing the sea component of the sea-island type fiber obtained by the composite spinning method of extruding and compounding. In addition, it is almost the same by removing the sea component of the sea-island type fiber obtained by the method of spinning after mixing the resin constituting the island component and the resin constituting the sea component, which is generally referred to as a mixed spinning method. It is difficult to obtain auxiliary fine fibers having a fiber diameter or auxiliary fine fibers having substantially the same diameter in the fiber axis direction. The resin constituting the auxiliary ultrafine fiber is not particularly limited. For example, nylon 6, nylon 66, polyamide such as nylon copolymer, polyethylene terephthalate, polyethylene terephthalate copolymer, polybutylene terephthalate, poly Consists of one or more synthetic resins such as polyesters such as butylene terephthalate copolymers, polyethylenes, polypropylenes, poly-4-methyl-1-pentenes, polyolefins such as olefin copolymers, polystyrenes, polyurethanes, and vinyl polymers. be able to. In addition, if the auxiliary microfiber contains a resin component (hereinafter sometimes referred to as “adhesive component”) that can participate in adhesion, and the adhesive component is bonded to the auxiliary microfiber, the auxiliary microfiber can be reliably fixed, This is a preferred embodiment because the ultrafine fibers do not fall off or become fuzzy. When adhering this auxiliary fine fiber, the auxiliary fine fiber can be composed only of an adhesive component made of the resin as described above, or a resin component having a melting point higher than the melting point of the adhesive component and this adhesive component (hereinafter, It may be composed of two or more types of resin components (sometimes referred to as “non-adhesive components”). If the auxiliary fine fiber is composed of two or more kinds of resin components including an adhesive component and a non-adhesive component like the latter, the fiber shape is maintained even if the auxiliary fine fiber is bonded, and the original function of the auxiliary fine fiber is achieved. It is difficult to prevent the formation of a uniform pore diameter. When the auxiliary fine fiber is composed of two or more types of resin components, the adhesive component occupies at least a part of the surface of the auxiliary fine fiber so that it can participate in bonding (the cross-sectional shape of the auxiliary fine fiber is, for example, Core-sheath type, eccentric type, side-by-side type, sea-island type, orange type, multiple bimetal type, etc., and the entire surface of the auxiliary fine fiber (the cross-sectional shape of the auxiliary fine fiber is the core-sheath type, eccentric type) It is more preferable that the adhesive component occupies the sea-island type. On the other hand, the non-adhesive component preferably has a melting point that is 10 ° C. or more higher than the melting point of the adhesive component so that the fiber shape can be maintained, and more preferably has a melting point that is 20 ° C. or more. In addition, it is preferable that the non-adhesive component has a melting point higher by 10 ° C. or more than the melting point of the adhesive component of the adhesive fiber described later, so that the fiber shape can be maintained by heat when bonding the adhesive fiber described later, It is more preferable to have a melting point that is 20 ° C. or higher. This auxiliary fine fiber composed of two or more kinds of resin components including an adhesive component and a non-adhesive component is suitable as a base for extruding the island component when spinning by a conventional composite spinning method. Obtained by spinning sea-island fiber using a material that can form a surface shape (eg, core-sheath type, eccentric type, side-by-side type, sea-island type, orange type, multiple bimetal type, etc.) and removing sea components be able to. In addition, auxiliary | assistant microfiber may have performances, such as a crimping expression and division property, besides having adhesiveness as mentioned above. As the auxiliary auxiliary fine fiber having the crimping expression of the former, a fiber in which two or more kinds of resin components are arranged so that the cross-sectional shape of the auxiliary fine fiber is an eccentric type or a side-by-side type can be used. As the auxiliary ultrafine fiber, a fiber in which two or more kinds of resin components are arranged so that the cross-sectional shape of the auxiliary ultrafine fiber is a sea-island type, an orange type, or a multiple bimetal type can be used. As will be described later, the auxiliary ultrafine fibers are preferably short fibers having a high degree of freedom (fiber length is 30 mm or less) so that they can be uniformly dispersed. However, when the auxiliary ultrafine fibers or sea-island fibers are cut. When the auxiliary microfibers or island components are crimped, the state becomes the same as that of the fibrillated fiber. Therefore, the auxiliary microfibers or sea island type fibers are difficult to bond between the auxiliary microfibers or island components when cutting. Is preferably used. Examples of such auxiliary ultrafine fibers or sea-island fibers that are difficult to press-bond include auxiliary ultrafine fibers with high crystallinity (island components in the case of sea-island fibers). More specifically, when the auxiliary ultrafine fiber (island component in the case of a sea-island fiber) contains polymethylpentene or syndiotactic polystyrene, or contains polypropylene, the melting point of the polypropylene is 166 ° C. When it is above (preferably 168 ° C. or higher), it is difficult to press-bond.

  On the other hand, the adhesive fiber is thicker than the auxiliary ultrafine fiber and has a fiber diameter of 8 μm or more so that the auxiliary ultrafine fiber is bonded to fix the auxiliary ultrafine fiber and strength can be imparted to the second auxiliary filtration nonwoven fabric (wet nonwoven fabric). It is. Further, the fiber diameter is less than 20 μm so that the arrangement of the auxiliary ultrafine fibers is not disturbed by the adhesive fibers to form a large aperture diameter. A more preferable fiber diameter of the adhesive fiber is 8 μm or more and 18 μm or less. This adhesive fiber may be composed of a single component, but it is preferably composed of two or more kinds of resin components so that the fiber form is maintained and the strength is excellent even after bonding. As an arrangement state of the two or more kinds of resin components, for example, the fiber cross-sectional shape may be a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, a multiple bimetal type, or the like. Among these, a core-sheath type, an eccentric type, or a sea-island type with a large amount of resin (adhesive component) that can participate in adhesion is preferable. This adhesive fiber can be composed of the same resin as the auxiliary fine fiber, but when the auxiliary fine fiber is not bonded, the auxiliary fine fiber is not melted by heat when bonding the adhesive fiber. Thus, the melting point of the adhesive component of the adhesive fiber is preferably 10 ° C. or more lower than the melting point of any resin component of the auxiliary ultrafine fiber, and more preferably 20 ° C. or more. On the other hand, when the adhesive component of the auxiliary ultrafine fiber is also bonded, the adhesive component of the adhesive fiber and the auxiliary ultrafine fiber can be simultaneously bonded to the adhesive component of the adhesive fiber and the adhesive component of the auxiliary ultrafine fiber. The melting point difference from the adhesive component is preferably within 35 ° C, more preferably within 30 ° C. Note that the melting point of the adhesive component of the adhesive fiber and the melting point of the adhesive component of the auxiliary fine fiber (if there are multiple types of auxiliary fine fibers, the resin component having the melting point closest to the melting point of the adhesive component of the adhesive fiber) When the difference from the melting point is 10 ° C. or more and 35 ° C. or less, the adhesive component of the auxiliary fine fiber can be adhered, or the adhesive component of the auxiliary fine fiber can be not adhered. In addition, when the auxiliary fine fiber includes an adhesive component and a non-adhesive component, the melting point of the adhesive component of the adhesive fiber is higher than the melting point of the non-adhesive component of the auxiliary fine fiber so that the auxiliary fine fiber can maintain the fiber shape. Is preferably 10 ° C. or more, more preferably 20 ° C. or more. Furthermore, when the adhesive fiber is composed of two or more types of resin components, resin components other than the adhesive component (non-adhesive) can be maintained by the heat at the time of bonding the adhesive fiber. The melting point of the component) is preferably 10 ° C. or higher, more preferably 20 ° C. or higher than the melting point of the adhesive component. This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) contains the auxiliary fine fibers and adhesive fibers as described above, and the mass ratio of these fibers changes as appropriate depending on the specific use and required physical properties of the second cylindrical filter. However, it is preferable that (auxiliary ultrafine fiber) :( adhesive fiber) = 30 to 70:70 to 30. If the amount of auxiliary fine fibers is 30 mass% or more, a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a narrow pore size distribution can be obtained. On the other hand, if the amount of adhesive fibers is 30 mass% or more, sufficient auxiliary fine fibers are obtained. Since the auxiliary ultrafine fibers are not likely to drop off, the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be given strength. A more preferable mass ratio is (auxiliary ultrafine fiber) :( adhesive fiber) = 35 to 65:65 to 35. In addition, these mass ratios say the ratio with respect to the whole mass of a 2nd auxiliary | assistant filtration nonwoven fabric (wet nonwoven fabric).

  This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is a fiber having a fiber diameter of more than 4 μm and less than 8 μm in addition to the above-mentioned auxiliary ultrafine fibers and adhesive fibers (hereinafter sometimes referred to as “intermediate fiber diameter fibers”). Can also be included. The content of the intermediate fiber diameter fiber is preferably 40 mass% or less, and more preferably 30 mass% or less, in view of the relationship with the auxiliary ultrafine fibers and the adhesive fibers. That is, it is preferable that (auxiliary ultrafine fiber) :( adhesive fiber) :( intermediate fiber diameter fiber) = 30 to 70:70 to 30: 0 to 40, (auxiliary ultrafine fiber) :( adhesive fiber): (Intermediate fiber diameter fiber) = 35 to 65:65 to 35: 0 to 30 is more preferable. The fibers constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) (for example, auxiliary ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) can be in an unstretched state, but are excellent in strength. The fiber extruded from the nozzle is preferably a fiber drawn by a mechanical action such as a drawing machine. The fiber length of the fibers (for example, auxiliary ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is not particularly limited, but the shorter the fiber length, the more the fiber. Therefore, the fiber length of the fibers constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is preferably 0.5 to 30 mm. Preferably, fibers (for example, auxiliary fine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) are cut to a fiber length of 0.5 to 30 mm. The fiber length is a length obtained by JIS L 1015 (chemical fiber staple test method) B method (corrected staple diagram method). This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is composed of the fibers as described above, and has a maximum pore size of not more than twice the average flow pore size (more preferably 1.9 times or less) and a narrow pore size distribution. . Ideally, the maximum pore size is one time the average flow pore size, that is, the total pore size is the same. The “maximum pore diameter” refers to a value measured by a bubble point method using a porometer (Polometer, manufactured by Coulter). When the fibers constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) (for example, auxiliary ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) are arranged substantially two-dimensionally, the arrangement of the fibers is regular. Therefore, the pore size distribution can be further narrowed. “The fibers are arranged substantially two-dimensionally” means a state where the fibers facing the thickness direction of the nonwoven fabric are not substantially arranged. For example, a fiber web formed by a wet method. On the other hand, it is a state that can be obtained when bonded only by adhesion without causing a fluid flow such as a water flow to act.

The surface density of the second auxiliary filtration nonwoven fabric of the second cylindrical filter is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is about 0.2. It is preferably about 0.5 to 0.7 g / cm ³ . The average flow pore diameter of the second auxiliary filtration nonwoven fabric in the second cylindrical filter is larger than the average flow pore diameter of the main filtration nonwoven fabric as described above. The degree thereof is appropriately changed depending on the fluid to be filtered, and is not particularly limited. However, it is preferably about 2 to 40 μm and more preferably about 2 to 20 μm larger than the main filtration nonwoven fabric. More specifically, as described above, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, more preferably about 0.5 to 20 μm. The average flow pore size is preferably 2.5 to 80 μm, more preferably 2.5 to 60 μm, still more preferably 2.5 to 40 μm.

  Such a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be produced, for example, as follows. First, at least auxiliary fine fibers and adhesive fibers that are not substantially fibrillated are prepared. The auxiliary ultrafine fibers have substantially the same fiber diameter, that is, the value obtained by dividing the standard deviation value of the fiber diameter distribution of the auxiliary ultrafine fibers by the average value of the fiber diameters of the auxiliary ultrafine fibers is 0.2 or less (preferably 0 .18 or less, 0 or more), it becomes easy to produce a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a narrow pore size distribution. In addition, it is preferable that fiber lengths, such as an auxiliary | assistant microfiber and an adhesive fiber, are 0.5-30 mm. In addition, when fibers (for example, auxiliary extra fine fibers) that are difficult to press during cutting are used, the dispersibility of the fibers is improved, and a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a narrow pore size distribution is easily manufactured. Then, using these fibers, a fiber web is formed by a conventional wet method. Since the fibers used are not substantially fibrillated, the fibers can be evenly dispersed in the water, which is a dispersion bath, and the fibers that make up the fibers are not entangled with each other. The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be produced. When forming this fiber web, a thickener is added to maintain a uniform dispersion state of the fiber, or a surfactant is added to increase the affinity between water and the fiber (particularly the affinity for water). A second auxiliary filtration nonwoven fabric (wet nonwoven fabric) with a narrow pore size distribution, which improves the dispersibility of the fibers by adding an antifoaming agent to remove bubbles generated by stirring or the like. ) Is easier to manufacture. Subsequently, after the fiber web is dried, or after drying, the adhesive component of the adhesive fiber is allowed to adhere (in some cases, the adhesive component of the auxiliary fine fiber can also be adhered) by applying heat (and pressure if necessary). The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be obtained by adhering the adhesive component of the adhesive fiber (and optionally the auxiliary ultrafine fiber adhesive component). When the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is produced by adhering the adhesive component of the adhesive fiber (optionally the auxiliary ultrafine fiber adhesive component) without causing a fluid flow such as a water flow to act on the fiber web, Since the fibers are two-dimensionally arranged, it becomes easy to produce a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a narrow pore size distribution.

The third tubular filter of the present invention is the above-mentioned main filtration nonwoven fabric and an auxiliary filtration nonwoven fabric (hereinafter sometimes referred to as a third auxiliary filtration nonwoven fabric) made of a melt blown nonwoven fabric having an average flow pore size larger than that of the main filtration nonwoven fabric. Is included. Since this third auxiliary filtration nonwoven fabric is composed of melt blown fibers that have not been subjected to a strong stretching action, the average flow pore size can be easily adjusted by carrying out heat treatment and pressure treatment. The 3rd cylindrical filter which has filtration performance can be manufactured easily. The surface density of the third auxiliary filtration nonwoven fabric of the third cylindrical filter is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is about 0.00. It is preferably about 0.5 to 0.7 g / cm ³ . The average flow pore size of the third auxiliary filtration nonwoven fabric in this third cylindrical filter is larger than the average flow pore size of the main filtration nonwoven fabric as described above. The degree thereof is appropriately changed depending on the fluid to be filtered, and is not particularly limited. However, it is preferably about 2 to 40 μm and more preferably about 2 to 20 μm larger than the main filtration nonwoven fabric. More specifically, as described above, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, more preferably about 0.5 to 20 μm. The average flow pore size is preferably 2.5 to 80 μm, more preferably 2.5 to 60 μm, still more preferably 2.5 to 40 μm. This “melt blown nonwoven fabric” refers to a nonwoven fabric obtained by a melt blow method. For example, a nozzle piece having an orifice diameter of 0.1 to 0.5 mm and a pitch of 0.3 to 1.2 mm and an orifice disposed at a temperature of 220 to 370 ° C. The resin is discharged at a rate of 0.02 to 1.5 g / min per orifice, and the discharged resin has a temperature of 220 to 400 ° C. and a resin discharge amount of 5 to 2 at a mass ratio. After the melt blown fiber is formed by acting 000 times the amount of gas, it can be collected by a collector such as a roll or a conveyor. In addition, in the direction orthogonal to the thickness direction of the melt blown nonwoven fabric, it is preferable that a portion with a large amount of melt blown fiber and a portion with a small amount of melt blown fiber are mixed because the filtration flow rate can be increased without impairing the filtration accuracy. The meltblown nonwoven fabric in which a portion having a large amount of meltblown fibers and a portion having a small amount are suitable is, for example, a nozzle piece that discharges meltblown fibers and a collector (for example, conveyor, roll, etc.) that collects meltblown fibers. The distance is increased or the meltblown fiber is placed between a pair of rolls (collector) (in particular, a pair of rolls in which the distance between the rolls changes, a pair of rolls in which the relative speed between the rolls changes, at least one of which is an eccentric roll. Produced by a pair of rolls), changing the flow rate of gas applied to the discharged resin for each orifice, or changing the flow rate of gas applied to the discharged resin over time. be able to. The meltblown fibers can be composed of one or more types of resin components similar to the meltblown fibers constituting the mixed nonwoven fabric as described above. When the meltblown fiber is composed of two or more kinds of resin components, the cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multiple bimetal type. As this melt blown nonwoven fabric, melt blown fibers collected and collected by a collector may be used as they are, or those subjected to heat treatment and / or pressure treatment in order to adjust the average flow pore size. May be. When performing the heat treatment and the pressure treatment, the heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment. In any case, the heating temperature is preferably 5 to 120 ° C. lower than the melting point of the meltblown fiber (the resin having the lowest melting point when the meltblown fiber is composed of two or more resin components having different melting points). In any case, the pressurizing treatment is preferably carried out under the condition that the linear pressure is 0.1 to 4 kN / cm.

  The auxiliary filtration nonwoven fabric (the first auxiliary filtration nonwoven fabric, the second auxiliary filtration nonwoven fabric, the third auxiliary filtration nonwoven fabric, and so on) constituting the cylindrical filter of the present invention has the above-described configuration, but the auxiliary filtration nonwoven fabric of the present invention. A composite of a spunbond nonwoven fabric may be used as the auxiliary filtration nonwoven fabric.

  The cylindrical filter of the present invention (the first cylindrical filter, the second cylindrical filter, the third cylindrical filter, and the like hereinafter) has the main filtration nonwoven fabric as described above and the various auxiliary filtration nonwoven fabrics as described above adjacent to each other. Are in a stacked state. This auxiliary filtration nonwoven fabric may be adjacent to only one side of the main filtration nonwoven fabric, or may be adjacent to both sides. For example, in the case of a so-called depth-type tubular filter, it is sufficient that the auxiliary filtration nonwoven fabric is adjacent to only one side of the main filtration nonwoven fabric. In the case of a so-called pleated tubular filter, It is preferable that the auxiliary filtration nonwoven fabric is adjacent to both surfaces. In addition, when the auxiliary filtration nonwoven fabric is adjacent to both surfaces of the main filtration nonwoven fabric, the same auxiliary filtration nonwoven fabric may be adjacent in terms of the average flow pore size, or different auxiliary filtration nonwoven fabrics in terms of the average flow pore size. It may be adjacent. The main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric may be in a combined state or in a non-bonded state. As the state of being joined as in the former, for example, after laminating the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric, the state of being bonded and integrated by heat treatment, or heat treatment and pressure treatment, the state of being unified by ultrasonic treatment, There are a state in which they are entangled and integrated by a needle or a fluid flow (preferably a water flow), and a state in which they are bonded and integrated by an adhesive. Moreover, the auxiliary filtration nonwoven fabric laminated | stacked adjacent to the main filtration nonwoven fabric does not need to be 1 type, and 2 or more types of auxiliary filtration nonwoven fabrics may be laminated | stacked. When two or more types of auxiliary filtration nonwoven fabrics are laminated in this manner, it is preferable that the auxiliary filtration nonwoven fabrics are sequentially laminated from the fluid inflow side to the fluid outflow side so that the auxiliary filtration nonwoven fabric has a small average flow pore size. In addition, when two or more types of auxiliary filtration nonwoven fabrics are laminated | stacked, even if these auxiliary filtration nonwoven fabrics exist in the state which couple | bonded, they may exist in the state which is not couple | bonded. Examples of the combined state as the former include, for example, a state in which the heat treatment or the adhesion and integration are performed by the heat treatment and the pressure treatment, a state in which they are integrated by the ultrasonic treatment, a needle or a fluid flow (preferably a water flow). There are an integrated state and an adhesive-bonded state with an adhesive.

  The cylindrical filter of the present invention is arranged around the perforated cylinder in a state where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric as described above are laminated adjacently. As this arrangement state, for example, in a state where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound around the perforated tube (so-called depth type), or in a state where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are folded For example, there are a state of being arranged around the perforated tube (so-called pleated type), or a case of having both of these states.

  In the former depth type cylindrical filter, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound around the perforated cylinder, but the number of windings is not particularly limited. The number of windings of the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric may be the same or different. That is, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric do not have to be adjacent over the entire circumference, and may be in a state of being adjacent only in a part of the region. When the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are adjacent to each other only in a part of the region, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are preferably adjacent to each other on the outflow side of the processing fluid. That is, when the processing fluid flows from the outside of the cylindrical filter and flows out to the inside, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently in the inner layer of the cylindrical filter. Preferably, conversely, when the processing fluid flows in from the inside of the cylindrical filter and flows out to the outside, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently in the outer layer of the cylindrical filter. It is preferable. The main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric may be wound in any manner, may be wound in a flat winding shape, or may be wound in a spiral shape. Further, in the case of the depth type, the auxiliary filtration nonwoven fabric laminated adjacent to the main filtration nonwoven fabric does not need to be one type, and two or more types of auxiliary filtration nonwoven fabrics different in terms of average flow pore diameter are used. It is preferable that the auxiliary filtration nonwoven fabric having a large average flow pore diameter is laminated in order from the fluid inflow side. By being laminated in this way, the filtration life is further increased. More specifically, it is preferable that an auxiliary filtration nonwoven fabric having an average flow pore size larger by about 2 to 40 μm than the main filtration nonwoven fabric is laminated in order from the main filtration nonwoven fabric to the fluid inflow side. In addition, a coarse filtration fiber sheet having an average flow pore size larger than the auxiliary filtration nonwoven fabric by about 2 to 40 μm is wound in a region different from the region in which the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently. Or, it may be arranged by folding. By arranging such a coarse filter fiber sheet, the filter life is further increased. This coarse filter fiber sheet may be in a state of being bonded to the auxiliary filtration nonwoven fabric or in a state of not being bonded. As the connected state as in the former, for example, at least heat treatment (preferably heat treatment and pressurization treatment), a state of being bonded and integrated, a state of being integrated by an ultrasonic seal, a needle or a fluid flow (preferably Are intertwined and integrated with water flow), and are in an integrated state with adhesive. The coarse filter fiber sheet only needs to have a larger average flow pore size (about 2 to 40 μm) than the auxiliary filtration nonwoven fabric (the auxiliary filtration nonwoven fabric having the largest average flow pore size when there are two or more types). 2 Wet nonwoven fabric manufactured in the same manner as the auxiliary filtration nonwoven fabric, Melt blown nonwoven fabric manufactured in the same manner as the third auxiliary filtration nonwoven fabric, Spunbond nonwoven fabric, Mixed nonwoven fabric manufactured in the same manner as the first auxiliary filtration nonwoven fabric, or Main filtration nonwoven fabric Nonwoven fabrics produced in the same manner can be used. Moreover, you may have the area | region arrange | positioned in the state by which the main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric were folded in addition to the area | region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric were wound.

  Another cylindrical filter of the present invention is a pleated cylindrical filter disposed around a porous cylinder in a state in which a main filtration nonwoven fabric and an auxiliary filtration nonwoven fabric are folded. The number of folds of the pleated cylindrical filter may be appropriately set depending on the application and necessary physical properties, and is not particularly limited. In the pleated tubular filter, if the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are folded, the surfaces of the main filtration nonwoven fabric may be brought into close contact with each other, and the filtration area may be reduced. It is preferable that the auxiliary filtration nonwoven fabric is laminated on both surfaces of the main filtration nonwoven fabric because there is a possibility that the filtration area will be reduced due to close contact. Thus, when the auxiliary filtration nonwoven fabric is laminated | stacked on both surfaces of the main filtration nonwoven fabric, the auxiliary filtration nonwoven fabric which has the same average flow volume diameter may be laminated | stacked on the front and back of the main filtration nonwoven fabric, and it has a different average flow volume diameter The auxiliary filtration nonwoven fabric may be laminated on the front and back surfaces of the main filtration nonwoven fabric. Also, in the case of a pleated cylindrical filter, the auxiliary filtration nonwoven fabric laminated adjacent to the main filtration nonwoven fabric does not need to be one type, and there are two or more types of auxiliary filtration nonwoven fabrics that differ in terms of average flow pore size. You may laminate | stack so that it may become an auxiliary | assistant filtration nonwoven fabric with a large average flow hole diameter in order from the main filtration nonwoven fabric to the fluid inflow side. Thus, when the auxiliary filtration nonwoven fabric is laminated | stacked, the filtration lifetime will become still longer. More specifically, it is preferable that an auxiliary filtration nonwoven fabric having an average flow pore size of about 2 to 40 μm is laminated in order from the main filtration nonwoven fabric to the fluid inflow side. When two or more types of auxiliary filtration nonwoven fabrics are laminated in this way, they may be laminated on both sides of the main filtration nonwoven fabric, or may be laminated only on one side, but only on one side of the main filtration nonwoven fabric. Even when a plurality of types of auxiliary filtration nonwoven fabrics are laminated, it is preferable that one auxiliary filtration nonwoven fabric is laminated on the other surface of the main filtration nonwoven fabric so that adhesion between the main filtration nonwoven fabrics can be suppressed. . In addition, when two or more types of auxiliary filtration nonwoven fabrics are laminated only on one side of the main filtration nonwoven fabric, the side on which the two or more types of auxiliary filtration nonwoven fabrics are laminated is the inflow side of the processing fluid. preferable. A coarse filtration fiber sheet having an average flow pore size larger than the auxiliary filtration nonwoven fabric by about 2 to 40 μm is wound on a region different from the region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are disposed in a folded state. You may have the turned area. When such a coarse filter fiber sheet is wound, the filtration life is further increased. This coarse filter fiber sheet may be in a state of being bonded to the auxiliary filtration nonwoven fabric or in a state of not being bonded. As the connected state as in the former, for example, at least heat treatment (preferably heat treatment and pressurization treatment), a state of being bonded and integrated, a state of being integrated by an ultrasonic seal, a needle or a fluid flow (preferably Are intertwined and integrated with water flow), and are in an integrated state with adhesive. The coarse filter fiber sheet only needs to have a larger average flow pore size (about 2 to 40 μm) than the auxiliary filtration nonwoven fabric (the auxiliary filtration nonwoven fabric having the largest average flow pore size when there are two or more types). 2 Wet nonwoven fabric manufactured in the same manner as the auxiliary filtration nonwoven fabric, Melt blown nonwoven fabric manufactured in the same manner as the third auxiliary filtration nonwoven fabric, Spunbond nonwoven fabric, Mixed nonwoven fabric manufactured in the same manner as the first auxiliary filtration nonwoven fabric, or Main filtration nonwoven fabric Nonwoven fabrics produced in the same manner can be used. Moreover, you may have the area | region where the main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric were wound other than the area | region arrange | positioned in the state by which the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric were folded. Note that the fold-folding process can be performed by a fold-folding machine, and the peak height, the peak interval, and the like can be appropriately set depending on the intended use and desired physical properties.

  The porous tube constituting the cylindrical filter of the present invention can be made of a conventionally known material such as metal or plastic. Moreover, although the cylindrical filter of this invention consists of the above basic structures, in order to prevent that a processing fluid dissipates, both ends of a cylindrical filter are sealed with a cap, or the shape of a cylindrical filter can be hold | maintained. Thus, the structure taken conventionally may be added, such as the porous net cylinder which consists of a metal or a plastics being installed in the outermost surface of a cylindrical filter.

  The cylindrical filter of the present invention is, for example, a liquid used in each manufacturing process such as food / beverage, electronics, medicine, chemistry, water treatment, photography, paint, plating, dyeing, machinery / steel, or a fluid such as a used liquid. It can use suitably for filtration of this.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
Splittable fiber (fineness: 2.2 dtex, fiber length: 45 mm, transverse) that can be divided into 16 parts (transverse shape: orange type) composed of a polypropylene component (melting point: 164 ° C.) and a high-density polyethylene component (melting point: 131 ° C.) Prepared with 8 polypropylene microfibers with a triangular surface shape and a fiber diameter of 4.4 μm, and 8 high-density polyethylene ultrafine fibers with a cross-sectional shape of approximately triangular and a fiber diameter of 4.4 μm) did. On the other hand, as an adhesive fiber, a core-sheath type composite adhesive fiber (fiber diameter: 17) whose core component is made of polypropylene (melting point: 165 ° C.) and whose sheath component (adhesive component) is low-density polyethylene (melting point: 106 ° C.). 0.7 μm, fiber length 51 mm). Next, after the splittable fiber and the core-sheath type composite adhesive fiber were mixed at a mass ratio of 80:20, a fiber web was formed by a card machine. Next, nozzles are arranged in a row with a nozzle diameter of 0.13 mm and a pitch of 0.6 mm with respect to the fiber web in a state in which the fiber web is supported by a support having a non-perforated portion having a thickness of 0.15 mm. From the nozzle plate, a water flow with a pressure of 14.7 MPa was alternately ejected twice on both sides, and the split fibers were entangled with each other to intertwine the ultrafine fibers to obtain a surface density of 60 g / m ² and a thickness of 0. A 34 mm split entangled nonwoven fabric was produced. Next, the split entangled nonwoven fabric is composed of a metal roll and a resin roll, and is passed between calender rolls (linear pressure: 1.9 kN / cm) set at a temperature of 60 ° C., and the surface density is 60 g / m ² , thickness. A main filtration nonwoven fabric having a thickness of 0.12 mm, an apparent density of 0.5 g / cm ³ , and an average flow pore size of 2.3 μm was produced. This main filtration nonwoven fabric includes split fibers that are not divided in the vicinity of the center in the thickness direction of the main filtration nonwoven fabric.

On the other hand, a nozzle piece having an orifice diameter of 0.2 mm and a pitch of 0.8 mm is heated to a temperature of 320 ° C., and a polypropylene resin is discharged at a rate of 0.06 g / min per orifice. A polypropylene melt blown fiber 2 having an average fiber diameter of 1.8 μm in the same direction as the direction of gravity is applied to the resin at a temperature of 330 ° C. and a mass ratio of 70 times the amount of resin discharged (melting point: 160 ° C) flow was formed. From the direction perpendicular to the flow of the polypropylene melt blown fiber 2, two opening cylinders 31 as shown in FIG. 7 are housed in a housing 32, and the core component is polypropylene from the opening machine 3 provided with an air nozzle 33. A core-sheath type thermoplastic stretched short fiber 4 having a fiber diameter of 21.6 μm and a fiber length of 38 mm, which is made of a resin (melting point: 160 ° C.) and whose sheath component is made of polyethylene resin (melting point: 135 ° C.), is supplied. Mixed with Fiber 2. In addition, the mixing mass ratio of the polypropylene melt blown fiber 2 and the core-sheath type thermoplastic stretched short fiber 4 was (polypropylene meltblown fiber 2) :( core-sheath type thermoplastic stretched short fiber 4) = 65: 35. A fiber group in which the polypropylene melt blown fibers 2 and the core-sheath type thermoplastic short staple fibers 4 were mixed was collected by a conveyor belt to form a mixed fiber web. The conveyor belt was made of a mesh body and sucked by a gas suction device from the side opposite to the belt collecting surface to prevent disturbance of the fibers constituting the mixed fiber web. Next, this mixed fiber web was subjected to a heat treatment for 3 minutes with a dryer having an atmospheric temperature of 145 ° C. to obtain a surface density of 50 g / m ² , a thickness of 0.33 mm, an apparent density of 0.15 g / cm ³ , and an average flow pore size of 13. A 7 μm mixed nonwoven fabric (first auxiliary filtration nonwoven fabric) was produced.

  Subsequently, in a state where the main filtration nonwoven fabric was sandwiched between the two first auxiliary filtration nonwoven fabrics, a folding filter was performed with a folding machine with a folding width of 14 mm to produce a laminated filter material. Next, the multilayer filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the multilayer filter material were fused with an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Example 2)
As a sea-island fiber, a fiber obtained by a composite spinning method in which 25 island components made of polypropylene are present in a sea component made of poly-L-lactic acid (hereinafter referred to as “PLLA”) (fineness: 1. 65 dtex, fiber length: 3 mm) was prepared. Next, this sea-island fiber was immersed in an aqueous solution of sodium hydroxide at a temperature of 80 ° C. and 10 mass% for 30 minutes to extract and remove PLLA, which is a sea component of the sea-island fiber, to obtain a polypropylene auxiliary ultrafine fiber (average fiber diameter: 1.8 μm, standard deviation of fiber diameter distribution: 0.15, melting point: 172 ° C., fiber length cut to 3 mm, non-fibrillated, stretched, substantially the same diameter in the fiber axis direction Have). On the other hand, as an adhesive fiber, a core-sheath type composite adhesive fiber (fiber diameter: 11) whose core component is made of polypropylene (melting point: 158 ° C.) and whose sheath component (adhesion component) is made of high-density polyethylene (melting point: 131 ° C.). .8 μm, fiber length cut to 10 mm, non-fibrillated, stretched). Next, the polypropylene auxiliary ultrafine fiber and the core-sheath type composite adhesive fiber are dispersed in a dispersion bath made of water at a mass ratio of 50:50, made by a paper machine, dried at a temperature of 140 ° C., and simultaneously the core-sheath. Only the adhesive component of the mold composite adhesive fiber is adhered, and a wet nonwoven fabric (second auxiliary) having an areal density of 38 g / m ² , a thickness of 0.34 mm, an apparent density of 0.11 g / cm ³ , and an average flow pore size of 12.1 μm Filtration nonwoven fabric) was produced. The fibers constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) were two-dimensionally arranged, and the maximum pore diameter was 1.7 times the average flow pore diameter. Moreover, the main filtration nonwoven fabric manufactured like the Example 1 was prepared.

  Next, in a state where the main filtration nonwoven fabric was sandwiched between the two second auxiliary filtration nonwoven fabrics, folding filtration was performed with a folding width of 14 mm using a folding machine to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Example 3)
A polypropylene spunbond nonwoven fabric having a surface density of 15 g / m ² , a thickness of 0.2 mm, an average fiber diameter of 37 μm, and an average flow pore diameter of 40 μm, prepared by a conventional spunbond method, was prepared. On the other hand, a nozzle piece having an orifice diameter of 0.3 mm and a pitch of 0.8 mm is heated to a temperature of 330 ° C., and a polypropylene resin is discharged at a rate of 0.33 g / min per orifice. A melt blown fiber (melting point: 162 ° C.) is formed on a resin by applying air at a temperature of 330 ° C. and 220 times the fiber discharge amount in a mass ratio, and then collecting them on a conveyor (nozzle piece and conveyor) And a distance of 49 cm), a melt blown nonwoven fabric was produced. This meltblown nonwoven fabric has a mixture of a portion with a large amount of meltblown fibers and a portion with a small amount in the direction orthogonal to the thickness direction. Next, the melt blown nonwoven fabric was subjected to a heat treatment with a dryer having an atmospheric temperature of 130 ° C., and then subjected to a pressure treatment under a linear pressure of 0.2 kN / cm to obtain a surface density of 30 g / m ² and a thickness of 0. A third auxiliary filtration nonwoven fabric of 17 mm, an apparent density of 0.18 g / cm ³ and an average flow pore size of 16 μm was produced. Next, the polypropylene spunbond nonwoven fabric and the third auxiliary filtration nonwoven fabric are integrated by ultrasonic sealing, and the surface density is 45 g / m ² , the thickness is 0.36 mm, the apparent density is 0.13 g / cm ³ , and the average flow rate is A third composite auxiliary filtration nonwoven fabric having a pore diameter of 14 μm and an average fiber diameter of 2.1 μm was produced. Moreover, the main filtration nonwoven fabric manufactured like the Example 1 was prepared.

  Next, in a state where the main filtration nonwoven fabric was sandwiched between the two third composite auxiliary filtration nonwoven fabrics, folding filtration was performed with a folding width of 14 mm by a folding machine to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Comparative Example 1)
A polypropylene spunbonded nonwoven fabric having a surface density of 25 g / m ² , a thickness of 0.24 mm, an average fiber diameter of 37 μm, and an average flow pore diameter of 40 μm manufactured by a conventional spunbond method was prepared. On the other hand, a main filtration nonwoven fabric produced in exactly the same manner as in Example 1 was prepared.

  Next, in a state where the main filtration nonwoven fabric was sandwiched between the two polypropylene spunbond nonwoven fabrics, a folding filter was carried out with a folding machine with a folding width of 14 mm to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

Example 4
A main filtration nonwoven fabric (60 cm length) produced in the same manner as in Example 1 and a mixed nonwoven fabric produced in the same manner as in Example 1 (first auxiliary filtration nonwoven fabric, 320 cm length) were prepared. Was also prepared by melt blowing, melt-blown nonwoven fabric A (40 cm length) of the mean flow pore size 3μm surface density of 80 g / m ^2, melt-blown nonwoven fabric B (40 cm length) of the mean flow pore size of 5μm surface density of 80 g / m ^2, And melt blown nonwoven fabric C (40 cm length) having an areal density of 80 g / m ² and an average flow pore size of 10 μm were prepared.

  Next, a main filtration nonwoven fabric is laminated on the mixed nonwoven fabric so that a position 120 cm from the left end of the first auxiliary filtration nonwoven fabric (mixed nonwoven fabric) coincides with the left end of the main filtration nonwoven fabric, and then the main filtration The melt blown nonwoven fabric A is laminated on the mixed nonwoven fabric so that the right end of the nonwoven fabric and the left end of the melt blown nonwoven fabric A match, and then the right end of the melt blown nonwoven fabric A and the left end of the melt blown nonwoven fabric B match. The melt blown nonwoven fabric B is laminated on the mixed nonwoven fabric, and the melt blown nonwoven fabric C is laminated on the mixed nonwoven fabric so that the right end of the melt blown nonwoven fabric B and the left end of the melt blown nonwoven fabric C coincide with each other. A filter media laminate was produced.

  Next, the filter material laminate is wound in a flat shape from the left end so that the side on which the main filtration nonwoven fabric of the filter material laminate is laminated is surrounded by a polypropylene porous cylinder, and has an inner diameter of 3 cm and an outer diameter. A depth-type cylindrical filter having a length of 6.5 cm and a length of 25 cm was manufactured.

(Comparative Example 2)
In place of the first auxiliary filtration nonwoven fabric used in Example 4, the same polypropylene spunbond nonwoven fabric as in Comparative Example 1 was used, except that the inner diameter was 3 cm and the outer diameter was 6.5 cm. A depth type cartridge filter having a length of 25 cm was manufactured.

The performance of the cylindrical filters of Examples 1 to 4 and Comparative Examples 1 to 2 was examined as follows.
1. Water flow resistance The pressure loss when water was passed through each cylindrical filter at a flow rate of 25 L / min was determined as water flow resistance. The results are shown in Table 1.
2. Filtration efficiency JIS11 class dust dispersed in water with a 10ppm concentration test solution is uniformly stirred and water is passed through each cylindrical filter at a predetermined flow rate (25L / min for pleated type, depth type) 10 L / min), and the filtrate after 1 minute of water flow was collected. The number of particles for each particle size contained in this filtrate and the test solution before filtration was measured with a particle size distribution analyzer (Coulter Multisizer II, manufactured by Coulter, Inc.). Next, the filtration efficiency at each particle size was calculated from the following formula, and the particle size at which 100% filtration efficiency was obtained was defined as the filtration accuracy of the cylindrical filter. The results are shown in Table 1.
Filtration efficiency [%] = {(A−B) / A} × 100
A: Number of particles before filtration, B: Number of particles after filtration Filtration life JIS11 class dust dispersed in water with a predetermined concentration of test solution (20 ppm for pleated type, 10 ppm for depth type) is stirred uniformly and at a predetermined flow rate in each cylindrical filter. Water was passed through (25 L / min for the pleated type, 10 L / min for the depth type). The pressure loss is measured sequentially for each water flow rate, and the total water flow rate processed until the differential pressure from the initial pressure reaches a predetermined value (200 kPa for pleated type, 100 kPa for depth type) The filtration life was assumed. The results are shown in Table 1.

この表１から明らかなように、本発明のプリーツ型筒状フィルタ及びデプス型筒状フィルタは、いずれも通水抵抗が低く、濾過精度及び濾過寿命の優れるものであることがわかった。また、本発明の筒状フィルタに使用した主濾過不織布及び補助濾過不織布からなる積層濾過材は主濾過不織布を損傷することなく、加工（襞折り加工、巻回加工）することができるものであった。このことは、表１の濾過精度を損なうことなく、濾過寿命が長く、優れた濾過性能を有するという点からも、加工時に主濾過不織布が損傷していないことがわかった。また、本発明の積層濾過材は襞折り加工時や巻回加工時の取り扱い作業性に優れるものであった。

As apparent from Table 1, it was found that the pleated tubular filter and the depth tubular filter of the present invention both have low water flow resistance and are excellent in filtration accuracy and filtration life. Moreover, the laminated filter material comprising the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric used in the cylindrical filter of the present invention can be processed (folded and wound) without damaging the main filtration nonwoven fabric. It was. This proved that the main filtration nonwoven fabric was not damaged at the time of processing also from the point of having a long filtration life and excellent filtration performance without impairing the filtration accuracy of Table 1. In addition, the laminated filter material of the present invention was excellent in handling workability at the time of folding and winding.

Schematic cross-sectional view of a splittable fiber that can be used in the present invention Schematic sectional view of another splittable fiber that can be used in the present invention Schematic sectional view of still another splittable fiber that can be used in the present invention Schematic sectional view of still another splittable fiber that can be used in the present invention Schematic sectional view of still another splittable fiber that can be used in the present invention Process drawing showing an example of a manufacturing process of the 1st auxiliary filtration nonwoven fabric Cross-sectional schematic diagram of an example of a spreader

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melt blow apparatus 2 Melt blow fiber 3 Opening machine 31 Opening cylinder 32 Housing 33 Air nozzle 4 Thermoplastic stretched fiber 5 Collecting body 6 1st auxiliary | assistant filtration nonwoven fabric A Dividing fiber

Claims (5)

Manufactured from two or more types of resin components and a main filtration nonwoven fabric containing two or more types of ultrafine fibers generated from separable fibers that can be divided by external force, and fibers that are not substantially fibrillated and have a fiber diameter of less than 20 μm. The fiber includes an ultrafine fiber having a fiber diameter of 4 μm or less, and an adhesive fiber having a fiber diameter of 8 μm or more and less than 20 μm, and the maximum pore diameter is not more than twice the average flow pore diameter, and Including an auxiliary filtration nonwoven fabric made of a wet nonwoven fabric having an average flow pore size larger than that of the main filtration nonwoven fabric, and the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are disposed adjacent to each other and disposed around a porous cylinder. A cylindrical filter characterized by comprising: The standard deviation of fiber diameter distribution of the ultrafine fibers constituting the auxiliary filtration nonwoven, a value obtained by dividing the average value of the fiber diameter of the ultrafine fibers, characterized in that more than 0.2, according to claim 1 Cylindrical filter. 3. The cylindrical filter according to claim 1 , wherein the cylindrical filter has a region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound around a porous cylinder. The cylinder according to any one of claims 1 to 3 , further comprising a region in which the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are disposed in a state of being folded around the perforated cylinder. Filter. The cylindrical filter according to any one of claims 1 to 4 , wherein the tubular filter has a region in which a coarse filtration fiber sheet having an average flow pore size larger than that of the auxiliary filtration nonwoven fabric is disposed.

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