JP2000279725A - Filter cartridge - Google Patents

Abstract

(57) [Abstract] (with correction) [Problem] To obtain a cylindrical filter cartridge excellent in liquid permeability, filtration life, stability of filtration accuracy, and the like. SOLUTION: A band-shaped short-fiber nonwoven fabric 15 containing thermoplastic fibers and having at least a part of fiber intersections bonded thereto,
7 is a filter cartridge 14 wound around a perforated tubular body 13 in a twill pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter cartridge for liquid filtration, and more particularly to a filter cartridge obtained by slitting a short-fiber non-woven fabric made of thermoplastic fiber into a strip shape and winding the slit into a twill shape.

[0002]

2. Description of the Related Art At present, various filters have been developed and produced for purifying fluids. Above all, cartridge-type filters (hereafter abbreviated as filter cartridges), in which filters can be easily replaced, are used for removing industrial particles such as suspended solids in liquid raw materials, removing cake flowing out of a cake filtration device, and purifying industrial water. Used in a wide range of fields.

Several types of filter cartridges have been proposed. The most typical one is a wound filter cartridge. This is made by winding a spun yarn as a filter material around a perforated cylindrical core in a twill shape, and has been used for a long time because it is easy and inexpensive to manufacture. Another structure is a nonwoven fabric laminated filter cartridge. This is a cylindrical filter cartridge made by winding several types of non-woven fabric such as carding non-woven fabric on a perforated cylindrical core in a stepwise manner. Have been.

[0004] However, these filter cartridges also have some disadvantages. For example, the particle collecting method of the wound filter cartridge collects the particles in the opening of the spun yarn itself, and also collects the particles in the fluff generated from the spun yarn and the gap between the spun yarns. It is difficult to adjust the amount of fluff, the amount of fluff, and the gap between spun yarns that are effective for filtration, so there is a limit to the types of filtration accuracy that can be manufactured. Is difficult. Further, since the spun yarn is made by twisting short fibers, there is a disadvantage that constituent fluids of the spun yarn fall off when a fluid flows through the filter cartridge.

[0005] Further, as shown in FIG.
The filter performance of a filter having a structure in which a wide nonwoven fabric 1 is directly wound around a so-called nonwoven fabric laminated filter cartridge is determined by the nonwoven fabric. Non-woven fabrics are manufactured by entanglement of short fibers with a card machine or air laid machine, and then heat-treating with a hot air heater or heating roll if necessary, or a direct method such as a melt blow method or a spun bond method. A method of making a nonwoven fabric from a resin is often used. However, any machine used for nonwoven fabric production such as card machine, air laid machine, hot air heater, heating roll, melt blow machine, spun bond machine, etc. Influence of physical properties often occurs. As a result, the quality of the filter cartridge may be poor, or the manufacturing cost may be increased by using advanced manufacturing techniques for eliminating unevenness. Further, in order to improve the filtration performance, the nonwoven fabric laminated filter cartridge needs to use about 2 to 6 types of nonwoven fabrics having different porosity and fiber diameter for each kind. Since different nonwovens may be used, this also increases the manufacturing costs.

As a method for solving such a problem of the conventional filter cartridge, for example, Japanese Utility Model 6
Japanese Patent No. -7767 discloses a filtration material having a diameter of about 3 mm, which is squeezed and narrowed by passing through a tapered cone while twisting porous tape-shaped paper or nonwoven fabric. There has been proposed a filter cartridge in which the inner cylinder is closely wound around the inner cylinder. In addition, by increasing the winding pitch of the winding toward the outside of the porous inner cylinder, large particles can be collected outside, and small particles can be collected at the center of the filter material, so that the filtering action can be obtained over a long period of time. I can do it. However, since the filtration material is crushed and squeezed, the porosity of the filtration material is reduced, the amount of particles captured by the filtration material itself is reduced, and the liquid permeability is reduced. In addition, since the gap between the filtration materials is small due to the close twill winding, there is no space that allows easy passage of liquid, and the liquid permeability of the filter itself is reduced. Also, by increasing the outer winding pitch, large particles are collected in the gap between the filtration materials, but since the area of the gap formed between the filtration materials is small, the gap is given a gradient. However, since the amount of trapped particles is small and the particles are easily clogged, the filtration life of the filter becomes very short.

[0007] As another method, Japanese Patent Application Laid-Open No. 4-45810 discloses that a slit nonwoven fabric made of a conjugate fiber in which 10% by weight or more of constituent fibers is divided into 0.5 denier or less is placed on a porous core tube. A filter wound so that the fiber density is 0.18 to 0.30 has been proposed. When this method is used, there is a feature that fine particles in a liquid can be captured by fibers having a small fineness. However, it is necessary to use physical stress such as high-pressure water to split the conjugate fiber, and it is difficult to uniformly split the entire nonwoven fabric by high-pressure water processing. If the division is not uniform, a difference occurs in the collection particle diameter between the well-divided part and the insufficiently-divided part in the nonwoven fabric, so that there is a possibility that the filtration accuracy becomes coarse. In addition, since the strength of the nonwoven fabric may decrease due to the physical stress used when dividing,
There is a possibility that the strength of the manufactured filter is reduced and the filter is easily deformed during use, or the porosity of the filter is changed and the liquid permeability is reduced. Furthermore, when the strength of the nonwoven fabric is low, it is difficult to adjust the tension when wound around the porous core tube, so that it may be difficult to finely adjust the porosity. Furthermore, since the manufacturing cost of the filter is increased due to the spinning technology required for producing easily splittable fibers and the increase in the operating cost during production, if the aforementioned problems in filtration performance are solved, the pharmaceutical industry and electronic It is thought that it can be used in some fields where high filtration performance is required, such as industry, but filters need to be inexpensive like filtration of pool water and filtration of plating solution for plating industry It seems difficult to use for the purpose.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and as a result, a short fiber non-woven fabric made of thermoplastic fiber is wound around a perforated cylindrical body in a twill shape, thereby making the liquid flow possible. The present inventors have found that it is possible to obtain a cylindrical filter cartridge excellent in properties, filtration life, stability of filtration accuracy, and the like, and have reached the present invention.

[0009]

The present invention has the following arrangement. (1) A filter cartridge comprising a band-shaped short-fiber nonwoven fabric containing thermoplastic fibers and having at least a part of the fiber intersections bonded thereto, in a twill shape around a perforated cylindrical body. (2) The filter cartridge according to item (1), wherein the band-shaped short-fiber nonwoven fabric is a nonwoven fabric mixed with another fiber containing at least 30% by weight of a thermoplastic fiber. (3) The thermoplastic fiber constituting the band-shaped short-fiber nonwoven fabric is a heat-adhesive conjugate fiber comprising a low-melting resin and a high-melting resin, wherein the difference between the melting points of both resins is 10 ° C. or more.
Or the filter cartridge according to item (2). (4) The low-melting resin is a resin selected from linear low-density polyethylene, low-density polyethylene, high-density polyethylene, polypropylene, a copolymer of propylene and another α-olefin, and a low-melting polyester. A filter cartridge according to Item (3). (5) The filter cartridge according to item (3), wherein the high melting point resin is a resin selected from high density polyethylene, polypropylene, a copolymer of propylene and another α-olefin, and polyethylene terephthalate. (6) The filter cartridge according to any one of (1) to (5), wherein the band-like short fiber nonwoven fabric is embossed by thermocompression bonding. (7) The filter cartridge according to any one of (1) to (5), wherein the fiber intersections of the band-shaped short fiber nonwoven fabric are heat-sealed. (8) The filter cartridge according to any one of (1) to (5), wherein a twist is added to the band-shaped short fiber nonwoven fabric. (9) The band-shaped short-fiber nonwoven fabric is formed into a pleated material having 4 to 50 folds, and is wound around a perforated cylindrical body in a twill shape (1).
The filter cartridge according to any one of items (1) to (5). (10) The filter cartridge according to the item (9), wherein at least a part of the folds of the fold is non-parallel. (11) The filter cartridge according to any one of (1) to (5), wherein the porosity of the pleated material is 60 to 95%. (12) The porosity of the filter cartridge is 65-65.
The filter cartridge according to any one of the above items (1) to (5), which has a percentage of 85%. (13) The filter cartridge according to any one of (1) to (5), wherein the porosity of the filter cartridge increases from the inner layer to the outer layer. (14) The width of the band-shaped short fiber nonwoven fabric is 0.5 cm or more, and the product of the width (cm) and the basis weight (g / m ² ) is 200 or less, according to any one of (1) to (5). Filter cartridge.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described specifically. Filter material of the filter cartridge of the present invention,
It is a band-shaped short-fiber non-woven fabric made of thermoplastic fiber, and at least a part of the fiber intersections are bonded.Since the fiber intersections are bonded, compared to a conventional wound-type filter using a spun yarn, the fiber Less shedding. In addition, because the band-shaped short fiber nonwoven fabric is wound around the perforated tubular body in a twill shape,
The filter has little variation in filtration performance in the filter length direction and is excellent in productivity. Furthermore, since the band-shaped short-fiber nonwoven fabric is pleated, the increase in the particle collection area due to the ruggedness of the folds and the apparent porosity increase due to the formation of the pleated material cause a change in the porosity of the filter medium during filter production. It is possible to provide a filter cartridge having a wide width, many types of filtration accuracy that can be manufactured, and an excellent filtration life.

As the thermoplastic fiber used in the present invention, any thermoplastic resin that can be melt-spun can be used. Examples thereof include polypropylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and copolymerized polypropylene (for example, mainly propylene, ethylene, butene-1,4-methylpentene-
Polyolefin-based resins, such as a binary or multi-component copolymer with 1), polyethylene terephthalate, polybutylene terephthalate, and low-melting polyesters obtained by copolymerizing an acid component by adding isophthalic acid in addition to terephthalic acid. Examples include thermoplastic resins such as polyester resins, polyamide resins such as nylon 6 and nylon 66, polystyrene (atactic polystyrene, syndiotactic polystyrene), polyurethane elastomer, polyester elastomer, and polytetrafluoroethylene. In addition, a functional resin may be used, such as using a biodegradable resin such as a lactic acid-based polyester to make the filter cartridge biodegradable. In addition, when a resin that can be polymerized with a metallocene catalyst such as a polyolefin resin or a polystyrene resin is used, it is preferable because characteristics of the metallocene resin such as an improvement in nonwoven fabric strength, an improvement in chemical resistance, and a reduction in production energy are utilized in the filter cartridge. These resins may be blended and used to adjust the thermal adhesiveness and rigidity of the short fiber nonwoven fabric. Among them, polyolefin-based resins such as polypropylene are preferable from the viewpoint of chemical resistance and price, and polyester-based resins and polyamide-based resins when used in relatively high-temperature liquids.
Alternatively, a syndiotactic polystyrene resin is preferred.

The thermoplastic fiber constituting the short-fiber nonwoven fabric used in the present invention is a composite fiber composed of a low-melting resin and a high-melting resin having a difference in melting point of 10 ° C. or more, preferably 15 ° C. or more. Thermal bonding at the joining point can be performed reliably. Although there is no particular upper limit for the melting point difference, the temperature difference between the highest melting point resin and the lowest melting point resin among the thermoplastic resins that can be melt-spun corresponds. In the case of a resin having no clear melting point, the flow start temperature is regarded as the melting point. When the fiber junction is thermally bonded, when a filter cartridge is formed, the possibility that particles captured near the fiber junction will flow out when the filtration pressure or water flow increases increases, and the filter cartridge is The deformation becomes smaller,
Furthermore, even if the fiber is deteriorated by a substance contained in the filtrate, the probability of the fiber falling off is reduced, which is preferable.

The combination of the low melting point resin and the high melting point resin of the conjugate fiber is not particularly limited as long as the difference in melting point is 10 ° C. or more, preferably 15 ° C. or more. Polypropylene, low density polyethylene / polypropylene, copolymer of propylene and other α-olefins / polypropylene, linear low density polyethylene / high density polyethylene,
Low density polyethylene / high density polyethylene, various polyethylene / polyethylene terephthalate, polypropylene / thermoplastic polyester, copolymerized polyester / polyethylene terephthalate, various polyethylene / nylon 6, polypropylene / nylon 6, nylon 6 / nylon 66, nylon 6 / polyethylene And terephthalate. In particular, when various polyethylene / polypropylene combinations, especially high-density polyethylene / polypropylene combinations are used, the rigidity and porosity of the short-fiber nonwoven fabric can be easily adjusted in the fusion step of fiber intersections during the production of the nonwoven fabric. preferable. When used in a relatively high-temperature liquid, a low-melting-point polyester / polyethylene terephthalate combination obtained by copolymerizing terephthalic acid and isophthalic acid as an acid component with ethylene glycol can also be suitably used.

In addition, fibers other than thermoplastic fibers can be used in the short-fiber nonwoven fabric used in the present invention. Examples include recycled fibers such as rayon and cupra, cotton, hemp,
Examples include natural fibers such as silk and pulp, and inorganic fibers such as carbon fiber and metal fiber. The mixing ratio between the fibers other than the thermoplastic fibers is not particularly limited, but the ratio contained in the nonwoven fabric must be such that the thermoplastic fibers contain at least 30% by weight. If the thermoplastic fiber content in the nonwoven fabric is less than 30% by weight, the strength of the nonwoven fabric when the fibers are thermally bonded is reduced, and the nonwoven fabric may be broken by the force applied during the processing when forming the filter cartridge. Further, since the number of heat-joined portions at the fiber intersections is reduced, the fibers are liable to fall off during filtration, and may be mixed into the filtrate.

The single fiber diameter of the short fiber non-woven fabric is not particularly limited because it varies depending on the use of the filter cartridge and the required filtration accuracy. In addition, if the basis weight is reduced in order to increase water permeability, the strength of the nonwoven fabric is reduced.
On the other hand, if the fiber is too thick, the short-fiber nonwoven fabric becomes very coarse, and even if it is a pleated material, the effect is not exhibited. Therefore, the fiber diameter is generally in the range of 5 to 150 μm.

The constituent fibers of the short-fiber nonwoven fabric do not necessarily have to have a circular cross section, and split fibers or irregular cross-section yarns can also be used. In this case, since the collection of fine particles is often performed on the surface of the fiber, the larger the surface area of the fiber, the larger the number of particles, and a filter cartridge with the same liquid permeability and high precision than when using a fiber with a circular cross section is used. Can be made.

Also, hydrophilic resin such as polyvinyl alcohol is mixed with raw material resin of thermoplastic fiber, cellulose fiber is mixed with short fiber non-woven fabric, or plasma processing is performed on the surface of short fiber non-woven fabric. It is preferable to improve the liquid permeability when using it for an aqueous liquid because the liquid permeability is improved.

The short fiber nonwoven fabric used in the present invention is produced by a carding method, an air laid method, a papermaking method, or the like.
The nonwoven fabric processed by these methods is also called a web, and has a low strength because the fiber intersections are not bonded, and it is difficult to process the filter cartridge of the present invention as it is. Although the strength can be increased by performing needle punching, water jet needle processing, or the like on the web, it is necessary to bond the fiber intersections in order to prevent the fibers from falling off during filtration. As a method of bonding the fiber intersection, a solvent or an emulsion of a resin serving as an adhesive is impregnated into the nonwoven fabric by a dipping method, a spraying method, or the like, or a resin powder is sprayed on the nonwoven fabric, and then the fiber is heated or dried. Although there is a method of bonding the intersections, usable filtrates are often limited due to heat resistance, chemical resistance and the like, and therefore, a method of performing thermal bonding using thermoplastic fibers as a binder is desirable.

The method of thermal bonding includes a method of thermocompression bonding using a device such as a hot flat calender roll machine, a hot embossing roll machine or an ultrasonic embossing machine, a hot air through air type, a vertical hot air jet type, an infrared heater. Examples of the method include a method using a heat treatment machine such as a mold. Among them, the method using a hot embossing roll machine has a high thermocompression bonding speed, so that the productivity is good and the production cost can be reduced. In this case, the area of the embossed thermocompression bonding is 5 to 3 times the area of the short fiber nonwoven fabric.
It is desirable to set it to 0%. If the area is less than 5%, the strength of the nonwoven fabric tends to decrease due to the small number of bonded portions at the fiber intersections, and the filter medium tends to fall off.
On the other hand, if it exceeds 30%, the liquid permeability when used as a filter tends to decrease. Although the productivity is inferior to the heat treatment machine of the hot air through air type, it is an effective method for preventing the filter medium from falling off because the bonding at the fiber intersections can be performed evenly. Further, when it is desired to adjust the porosity or thickness of the band-shaped short fiber nonwoven fabric, a flat calender roll may be passed after the heat treatment machine.

The basis weight of the short-fiber nonwoven fabric, that is, the weight per unit area of the nonwoven fabric, is preferably from 5 to 200 g / m ² . When this value is less than 5 g / m ² , the fiber amount is reduced, so that the unevenness of the nonwoven fabric is increased, the strength of the nonwoven fabric is reduced, or the thermal bonding at the fiber intersection as described above becomes difficult. is there. On the other hand, if this value is 2
When it is larger than 00 g / m ² , the nonwoven fabric becomes thicker, and it becomes difficult to form a fold. In addition, even if the thickness of the nonwoven fabric is thin, water permeability is reduced when a filter cartridge is used because there are few voids in the nonwoven fabric.

As a method for forming a short fiber nonwoven fabric into a belt shape,
A method of forming a band-shaped short fiber nonwoven fabric by adjusting the width at the time of web formation can also be used, but a method of slitting a wide short fiber nonwoven fabric into a band shape is preferable from the viewpoint of productivity and uniformity of the width. The slit width at this time varies depending on the basis weight of the nonwoven fabric to be used, but is preferably 0.5 cm or more.If the width is smaller than 0.5 cm, the nonwoven fabric may break at the time of slitting,
In addition, it becomes difficult to adjust the tension when the band-shaped nonwoven fabric is wound on the twill later. Furthermore, when a filter having the same porosity is produced, the winding time is increased and the productivity is reduced. On the other hand, the upper limit of the slit width varies depending on the basis weight, and the value of slit width (cm) × basis (g / m ² ) is preferably 200 or less. When this value is greater than 200,
When wound around a perforated tubular body, when the band-shaped short-fiber nonwoven fabric is squeezed, its diameter becomes too large.When it is wound around a perforated tubular body, the space other than the short-fiber nonwoven fabric occupies in the filtration layer. However, it becomes difficult to control the porosity of the filtration layer. In addition, as the thickness increases, the winding length per filter cartridge becomes shorter, and the gap formed between the band-shaped short fiber nonwoven fabrics also decreases. As a result, it becomes difficult to change the porosity of the filtration layer, adjust the filtration accuracy by the gap, or improve the filtration life.

As an example of a method of forming a fold in the band-shaped short fiber nonwoven fabric, there is a method of preforming the fold of the band-shaped short fiber nonwoven fabric with an appropriate fold forming guide, and then processing the fold through small holes or the like. . An example of this manufacturing method is shown in FIG.
Shown in When this method is adopted, the band-shaped short fiber nonwoven fabric 2
Is preformed in a cross-sectional shape through a fold forming guide 5 and then formed into a pleated material through a small hole guide 6, and the pleated material is taken in the direction of A in the figure and wound around a perforated cylindrical body. And a filter cartridge. As a winding machine for winding a pleated material around a perforated cylindrical body, a winder used for a usual thread-wound filter cartridge can be used.

Next, the fold forming guide will be described. As the fold forming guide, a guide formed by bending a metal round wire having a diameter of about 1 to 3 mm or a cutout of a metal plate having a thickness of about 1 to 3 mm is used. If friction is a problem, the surface of the metal may be treated with a fluororesin. Examples of the shape are shown in FIGS. In the example given here, the fold forming guide 5 includes the external control guide 3 and the internal control guide 4. The shape of the fold forming guide 5 is not particularly limited, but any shape may be used as long as the folds are converged so that the folds are not parallel as much as possible in the cross-sectional shape of the fold formed from the guide. 5A, 5B, and 5C show examples of the cross-sectional shape of the pleated material thus formed, but the present invention is not limited to these shapes. In these aspects of the invention, the formation of folds that are converged such that at least a portion of the folds are non-parallel is a preferred aspect of the invention. That is, when a part of the fold is non-parallel as in the cross-sectional shape of FIG. 5, FIG.
Compared to the case where most of the pleats are parallel as shown in (B), even when the filtration pressure is applied to the pleats from a vertical direction as shown by the arrow, the shape retention force of the pleats is stronger, and the filtration by the pleats is performed. Function can be retained. In other words, it can be said that the non-parallel folds are superior to the parallel folds in suppressing the pressure loss of the filter cartridge in order to maintain the gap between the folds.

It is not always necessary that the number of the gusset forming guides is one. If several guides having different shapes and sizes are arranged in series, the cross-sectional shape of the band-shaped short fiber nonwoven fabric is gradually changed. In addition, since the cross-sectional shape of the pleated material is constant depending on the location, quality unevenness is eliminated, which is preferable. For example, after applying a large number of pleats to a band-like short fiber nonwoven fabric using a comb-shaped pleat forming guide 8 as shown in FIG.
By deforming so as to increase the number of folds by passing through a narrower rectangular guide 9, the folds can be arranged in an at random random non-parallel arrangement.

In the present invention, when the band-shaped short-fiber nonwoven fabric is wound into a perforated cylindrical body after being formed into a pleated material, the final number of pleated materials is 4 to 50, and more preferably seven.
~ 45. If the number of folds is less than 4, the effect of expanding the filtration area by providing folds is poor. On the other hand, when the number of pleats is 5
If the number of folds exceeds 0, the folds become too small, making it difficult to manufacture, and the increase in the number of folds does not improve the filtration performance.

Further, the cross-sectional shape of the pleated material 7 can be fixed by heating the pleated material 7 having passed through the aforementioned small hole guide 6 with hot air or an infrared heater. This step is not always necessary, but when the cross-sectional shape of the pleated material is complicated, or when a highly rigid short-fiber nonwoven fabric is used, the cross-sectional shape may collapse from the designed shape. Therefore, it is preferable to perform such heat processing.

On the other hand, the band-shaped short fiber nonwoven fabric may be wound after being twisted. In this case, a winder used for a normal thread-wound filter cartridge can be used for the winding machine. By adding twist to the nonwoven, the apparent porosity of the nonwoven can be changed by the number of twists per unit length, or the strength of twisting,
Filtration accuracy can be adjusted. The number of twists at this time is
The range is preferably 50 to 500 times per 1 m of the band-shaped short fiber nonwoven fabric. If this value is less than 50 times, little effect due to twisting can be obtained. This value is 500
If the number is larger than the number of times, the short-fiber nonwoven fabric is strongly squeezed and the fibers are clogged, and the particle collecting performance is unfavorably deteriorated.

Next, the porosity of a pleated material (hereinafter, abbreviated as a band-shaped short fiber non-woven fabric bundle) in which the band-shaped short fiber non-woven fabric is bundled will be described. As shown in FIG. 8, the cross-sectional area of the band-shaped short-fiber nonwoven fabric bundle is defined by an oval 10 having the minimum area including the band-like short-fiber nonwoven fabric bundle 7 (the oval is a polygon in which each of the internal angles is within 180 degrees). ) And the cut length of the banded short fiber nonwoven fabric bundle, the porosity of the banded short fiber nonwoven fabric bundle is defined using the following equation.

(Apparent Volume of Banded Short-Fiber Nonwoven Fabric Bundle)
= (Cross-sectional area of banded short fiber nonwoven fabric bundle x cutting length of banded short fiber nonwoven fabric bundle)

(True volume of the band-shaped short-fiber nonwoven fabric bundle) =
(Weight of cut short-fiber nonwoven fabric bundle) / (Density of raw material of short-fiber nonwoven fabric bundle)

(Porosity of the band-shaped short-fiber nonwoven fabric bundle) =
{1- (True volume of band-shaped short fiber nonwoven fabric bundle) / (apparent volume of band-shaped short fiber nonwoven fabric bundle)} × 100%

The porosity of the band-shaped short nonwoven fabric bundle defined by this formula is preferably from 60 to 95%, more preferably from 80 to 92%. By setting this value to 60% or more, the band-shaped short fiber non-woven fabric bundle can be prevented from becoming unnecessarily dense, the pressure loss when used as a filter cartridge can be sufficiently suppressed, and the band-shaped short fiber non-woven fabric bundle can be further reduced. The efficiency of collecting particles in the object can be further improved. By setting this value to 95% or less, winding around a perforated cylindrical body becomes easy, and when used as a filter cartridge, the deformation of the filter medium due to the applied pressure can be further reduced. Examples of a method for adjusting this include adjusting the winding tension, adjusting the shape of a guide such as a fold forming guide, and the like.

When the band-shaped short-fiber nonwoven fabric bundle is produced, granular activated carbon, an ion-exchange resin or the like may be mixed and processed as long as the effects of the present invention are not impaired. In this case, in order to fix the granular activated carbon or the ion exchange resin or the like, the band-shaped short fiber nonwoven fabric may be adhered with a suitable binder before or after processing into a bundle or a pleated material. After mixing the ion-exchange resin or the like, the mixture may be heated and thermally bonded to the constituent fibers of the short-fiber nonwoven fabric.

Next, the perforated cylindrical body used in the present invention will be described. The perforated cylindrical body serves as a core material of the filter cartridge, and its material and shape are not particularly limited as long as they have strength enough to withstand external pressure during filtration and pressure loss is not extremely high. . For example, it may be a cylindrical injection molded product having a lattice-shaped opening, such as a polyethylene or polypropylene core material used in a normal filter cartridge, or may have many porous ceramics or small holes. A stainless steel plate processed into a cylindrical shape may be used. Alternatively, another filter cartridge such as a fold-folded filter cartridge or a nonwoven fabric wound type filter cartridge may be used.

Next, a method of winding the band-shaped short fiber nonwoven fabric bundle around the perforated cylindrical body will be described. As a winder,
A commercially available winder for a wound filter cartridge can be used. As shown in FIG. 9, the traverse traverses in the directions of B and B 'after passing the fold forming guide 5 and the small hole guide 6 so that the band-shaped short fiber nonwoven fabric 2 can be wound in the direction of A. A filter cartridge 14 is obtained by winding the guide 11 through a perforated cylindrical body 13 attached to a spindle 12 rotating in the direction C. The step of producing the filter cartridge from the band-shaped short fiber nonwoven fabric does not necessarily have to be a continuous step, and the band-shaped short fiber bundle may be wound around a bobbin after being formed, and then wound up with a winder. Since the yarn path of the winder is swung in a twill shape by a traverse cam installed in parallel with the spindle, a band-shaped short fiber nonwoven fabric aggregate is swung in a twill shape around the perforated tubular body. The winding conditions at that time may be set in accordance with the production of a normal thread-wound filter cartridge.
The winding may be performed at 0 to 2000 rpm while adjusting the feeding speed and applying an appropriate tension. At this time, the porosity of the filtration layer can be changed by changing the setting of the tension adjusting device, the rotation speed of the spindle, and the like.
By using these methods, the porosity can be increased from the inner layer to the outer layer of the filtration layer, so that the filtration life can be improved by deep-layer filtration. In addition, the filtration accuracy can be easily changed not only by changing the type and configuration of the band-shaped short-fiber nonwoven fabric bundle, but also by changing the winding pattern by adjusting the ratio of the traverse speed of the traverse cam to the rotation speed of the bobbin. it can. The method of applying the winding pattern can use the method of a usual thread-wound filter cartridge which is already known. As shown in FIG. 10, when the interval 15 between the yarn (in the case of the present invention, the band-shaped short-fiber non-woven fabric bundle) and the yarn wound on the layer immediately below it is wide, the filtration accuracy becomes coarse, and conversely If it is narrow, the filtration accuracy will be fine. As the number of winds (the number of rotations of the spindle while the traverse guide moves 25 cm), 3 to 5 rotations are generally used. According to these methods, the band-shaped short fiber nonwoven fabric bundle is wound to an outer diameter of about 1.5 to 3 times the outer diameter of the perforated tubular body to form a filter cartridge. In this method, the winding pattern can be changed by adjusting the ratio of the traverse speed of the traverse guide to the rotation speed of the spindle, so that filter cartridges having various performances can be manufactured from the same band-shaped short fiber nonwoven fabric aggregate. Further, the end face of the filter may be kept in a rolled-up state, or may be 3 mm thick.
A gasket of foamed polyethylene may be attached to the filter cartridge so as to enhance the adhesion between the end face of the filter cartridge and the housing.

In the filter cartridge thus obtained, the porosity of the filtration layer formed of the banded short-fiber nonwoven fabric bundle is preferably in the range of 65 to 85%. If this value is less than 65%, the fiber density tends to be too high and the liquid permeability tends to be poor. Conversely, if this value is greater than 85%, the strength of the filtration layer is weakened, and when the filtration pressure is high, problems such as deformation of the filter cartridge and particles collected once flowing out into the filtrate are likely to occur. It is because it becomes. When the porosity of the filtration layer is changed to increase the porosity of the outer layer, the porosity is divided into three equal parts in the thickness direction of the filtration layer, and when the inner layer, the intermediate layer, and the outer layer are formed, the inner layer and the outer layer are separated. Is preferably in the range of 3 to 15%. If it is less than 3%, the difference in porosity is small, so that no improvement in the filtration life can be seen.
%, On the contrary, the difference in porosity is too large, and the concentration of particles is concentrated in a certain layer. Therefore, in this case, the filtration life cannot be improved. The range of the porosity of each layer is desirably within the range of the porosity of the entire filtration layer for the reason described above.

In addition, the liquid permeability and collection efficiency can be improved by making a cut or making a hole in the band-shaped short fiber nonwoven fabric in advance. In this case, the number of cuts is appropriately about 5 to 100 per 10 cm of the band-shaped short-fiber nonwoven fabric, and when a hole is formed, the ratio of the area of the opening is preferably about 10 to 80%. . Respectively,
If the value is below the lower limit, no effect is exhibited, and if the value is above the upper limit, the strength of the nonwoven fabric is weakened or the filtration accuracy is reduced. The filtering performance can also be adjusted by using a plurality of band-shaped short-fiber nonwoven fabrics at the time of winding, or by winding them together with other yarns such as spun yarns. Further, as shown in FIG. 11, after the band-shaped short fiber non-woven fabric bundle is wound to a certain diameter to form the inner layer 16, a wide non-woven fabric is wound in the middle to insert the non-woven fabric layer 17.
Then, a method of forming the outer layer 18 by winding the band-shaped short fiber nonwoven fabric bundle by traversing may be used. If this method is carried out when the winding efficiency is not sufficiently obtained when the yarn is wound with the yarn interval wide, the collecting efficiency can be easily adjusted.

[0038]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples. In each example, the evaluation of the physical properties, filtration performance, and the like of the filtering material was performed by the methods described below.

(Weight and thickness) The area of the nonwoven fabric is 625c
The nonwoven fabric was cut out from three places so as to obtain m ² , the weight was measured and converted into the weight per square meter, and the average value was defined as the basis weight (g / m ² ). The thickness of the nonwoven fabric was arbitrarily measured at five points using a thickness measuring machine, and the average value was defined as the thickness (mm) of the nonwoven fabric. The measuring element of the thickness measuring machine had a diameter of 20 mm and applied a load of 10 g / cm ² .

(Fiber diameter) Samples were randomly sampled from a nonwoven fabric at five locations, photographed with a scanning electron microscope, and
Twenty fibers were randomly selected at each location, their fiber diameters were measured, and the average value was used as the fiber diameter (μ
m).

(The number of folds in the band-shaped short fiber non-woven fabric bundle) After fixing the band-shaped short fiber non-woven fabric bundle with an epoxy adhesive,
Five sections were cut at arbitrary positions, and the cross section was photographed with a microscope. From the photograph, the number of folds of the bundle of band-shaped short fiber nonwoven fabrics was counted as one in each of the mountain folds and the valley folds, and a half of the average number of the cut five points was taken as the number of folds.

(Porosity of band-shaped short fiber non-woven fabric bundle) After fixing the cross-sectional shape of the band-shaped short fiber non-woven fabric bundle with an epoxy-based adhesive, the cross-section was cut at five arbitrary positions, and the cross-section was photographed with a microscope. . The photograph was image-analyzed to determine the cross-sectional area of the banded short fiber nonwoven fabric bundle. A band-like short fiber nonwoven fabric bundle at another location was cut to a length of 10 cm, and the porosity (%) was calculated from the weight and the cross-sectional area obtained previously using the following equation. (Apparent volume of band-shaped short fiber nonwoven fabric bundle) = (cross-sectional area of band-shaped short fiber nonwoven fabric bundle × cut length of band-shaped short fiber nonwoven fabric bundle) (True volume of band-shaped short fiber nonwoven fabric bundle) = (band-shaped short fiber nonwoven fabric) (Weight of bundled material) / (specific gravity of raw material for bundled short-fiber nonwoven fabric) (porosity of bundled short-fiber nonwoven fabric bundle) = ｛1- (true volume of bundled short-fiber nonwoven fabric bundle) / (band-like short fiber nonwoven fabric) Apparent volume of bundled product) x 100%

(Yarn spacing) A belt wound in a layer one layer below the band-like short fiber non-woven fabric bundle (or a thread wound around a perforated cylindrical body in the following examples) in the surface layer. The interval (shown at 15 in FIG. 10) with the short-fiber nonwoven fabric bundle was measured at 10 points for one filter cartridge, and the average value was defined as the yarn interval (mm).

(Porosity of Filtration Layer) The outer diameter, inner diameter, length, and weight of the filter cartridge were measured, and the porosity (%) was determined using the following equation. In order to determine the porosity of only the filtration layer, the outer diameter of the perforated cylinder is used for the inner diameter of the filtration layer, and the value obtained by subtracting the weight of the perforated cylinder from the weight of the filter cartridge is used for the weight of the filtration layer. Was. (Apparent volume of filtration layer) = π ｛(outer diameter of filter cartridge) ² − (inner diameter of filtration layer) ² ｝ × (length of filter cartridge) / 4 (true volume of filtration layer) = (weight of filtration layer) / (filtration Density of bed material) (porosity of filtration layer) = ｛1-(true volume of filtration layer)
/ Apparent volume of the filtration layer) x 100% If the filtration layer is provided with a gradient of porosity, the bundle of band-shaped short-fiber nonwoven fabrics is unwound by 1/3 of the thickness of the filtration layer, and the unwound band is unwound. The porosity of the inner layer, the intermediate layer, and the outer layer was calculated by measuring the weight and the outer diameter of the short fiber nonwoven fabric bundle.

(Filtration Accuracy, Pressure Loss, Filtration Life) One filter cartridge having a length of 250 mm is attached to the housing of the circulating filtration performance tester, and the flow rate is adjusted to 30 liters per minute by a pump to circulate water. At this time, the pressure difference between the inlet side and the outlet side of the housing was measured and the pressure loss (MP
a). Next, JIS Z 890 is added to the circulating water.
8 types of test powder I (abbreviated as JIS 8 types; median diameter: 6.6 to 8.6 μm) and 7 types (JIS 7)
Abbreviated as seed. (Middle diameter: 27-31 μm) is mixed at a weight ratio of 1: 1 and a cake is continuously added at a rate of 0.5 g / min. A stock solution and a filtrate are collected 5 minutes after the start of the addition. After diluting the collected liquid at an appropriate magnification, the number of particles for each particle diameter contained in each liquid was calculated for the collection efficiency for each particle diameter using a light-blocking particle detector. Next, the value was interpolated to obtain a particle size showing a trapping efficiency of 80%, which was defined as an initial filtration accuracy (μm). Further, the cake was further added, and when the pressure loss reached 0.2 MPa, the undiluted solution and the filtrate were collected, and the same measurement was carried out.
The filtration accuracy (μm) at the time of MPa was determined. The time from the start of cake addition to the time when the pressure reached 0.2 MPa was defined as the filtration life (minute).

(Fiber drop) One filter cartridge having a length of 250 mm is attached to the housing of the circulating filtration performance tester, and the flow rate of the filter is adjusted to 10 liters per minute by a pump, and ion-exchanged water is passed through. 0.5 liter of 5 liters of the initial filtrate collected at the outlet of the housing was used for 0.8 hole diameter.
μm, filtered with a nitrocellulose filter paper having a diameter of 25 mm. ×: when there are 20 or more fibers having a length of 1 mm or more on the filter paper, Δ: when 10 to 19 fibers, ○: when 5 to 9 fibers
The following cases were evaluated as ◎, and fiber detachment was determined.

(Example 1) As a band-shaped short fiber nonwoven fabric,
It is made of polypropylene fiber and has a basis weight of 30.5 g / m ² ,
0.22mm thickness, fiber diameter 18μm, slit width 4c
m, 15% of the area of the nonwoven fabric was a nonwoven fabric thermocompressed with a hot embossing roll. In addition, a polypropylene injection molded product having an inner diameter of 30 mm, an outer diameter of 34 mm, and a length of 250 mm was used as the perforated cylindrical body. When the band-shaped short fiber non-woven fabric is wound around a perforated cylindrical body by a winder, the band-shaped short fiber non-woven fabric having eight pleats and a porosity of 87% is passed through a pleat forming guide having the shape shown in FIG. 3 before the traverse guide. A convergence was formed. The spindle speed is 1000 rpm
m, and wound around a perforated cylindrical body until the outer diameter becomes 62 mm,
A cylindrical filter cartridge having a yarn interval of 0.7 mm and a porosity of the filtration layer of 79% was obtained. Table 1 shows the measurement results of the filtration performance.

[0048]

[Table 1]

(Example 2) As a band-shaped short fiber nonwoven fabric,
It consists of a fiber blended with 50% by weight of polyethylene terephthalate fiber and 50% by weight of rayon fiber, and has a basis weight of 31.2%.
g / m ² , a thickness of 0.23 mm, a fiber diameter of 16 μm, a slit width of 4 cm, and 15% of the nonwoven fabric area were thermocompressed with a hot embossing roll. In addition, the injection molded product made of polypropylene of Example 1 was used as the perforated cylindrical body. When the band-shaped short fiber non-woven fabric is wound around a perforated cylindrical body by a winder, the band-shaped short fiber non-woven fabric having 12 folds and a porosity of 89% is passed through a pleated guide having the shape shown in FIG. 3 before the traverse guide. A convergence was formed. This was wound around a perforated cylindrical body at a spindle rotation speed of 1000 rpm until the outer diameter became 62 mm, to obtain a cylindrical filter cartridge having a yarn interval of 0.6 mm and a porosity of the filtration layer of 79%. Table 1 shows the measurement results of the filtration performance. Due to the increase in the number of folds, the collection area of the band-shaped short fiber nonwoven fabric bundle increased, and the filtration life was improved as compared with Example 1.

Example 3 As a short-fiber non-woven fabric in the form of a band,
A sheath-core type composite fiber having a weight ratio of 5: 5 using high-density polyethylene on the sheath side and polypropylene on the core side has a basis weight of 2
A nonwoven fabric having a thickness of 9.6 g / m ² , a thickness of 0.25 mm, a fiber diameter of 17 μm, a slit width of 4 cm, and a fiber intersection point thermally bonded by a heat-through-air heat treatment machine was used. In addition, the injection molded product made of polypropylene of Example 1 was used as the perforated cylindrical body. When the band-shaped short fiber nonwoven fabric is wound around a perforated cylindrical body by a winder, the number of folds is 1 by passing the pleated guide having the shape shown in FIG. 3 in front of the traverse guide.
2. A banded short fiber nonwoven fabric bundle having a porosity of 90% was formed. This is wound around a perforated tubular body at a spindle rotation speed of 1000 rpm until the outer diameter becomes 62 mm, and the yarn interval is 0.5
mm, a cylindrical filter cartridge having a filtration layer porosity of 80% was obtained. Table 1 shows the measurement results of the filtration performance. Since the number of heat bonding points increased due to processing by the heat through-air heat treatment machine, falling off of fibers was reduced as compared with Example 2.

(Example 4) As a band-shaped short fiber nonwoven fabric,
Polyethylene terephthalate on the core side and ethylene glycol / terephthalic acid (75 mol%) / isophthalic acid (25 mol%) low melting point polyester (melting point) on the sheath side
185 ° C) and a sheath-core type composite fiber having a basis weight of 33.
A non-woven fabric having a thickness of 0.26 mm, a fiber diameter of 21 μm, a slit width of 4 cm, a fiber intersection of ² g / m ² , and a fiber intersection was thermally bonded by a heat-through-air heat treatment machine was used. In addition, an injection-molded product made of polybutylene terephthalate having the same dimensions as in Example 1 was used as the perforated cylindrical body. When the band-shaped short-fiber nonwoven fabric was wound around a perforated cylindrical body by a winder, a band-shaped short-fiber nonwoven fabric bundle having twelve folds was formed by passing the pleated guide having the shape shown in FIG. 3 before the traverse guide. . By gradually changing the tension at the time of winding to 10 N at the start of winding and 2 N at the end of winding, a cylindrical filter cartridge having an outer diameter of 62 mm, a yarn interval of 0.5 mm, and a porosity of the filtration layer of 82% was obtained. The porosity of the inner layer, the intermediate layer, and the outer layer was 79%, 81%, and 84%, respectively. Table 1 shows the measurement results of the filtration performance. By increasing the porosity from the inner layer to the outer layer, deep-layer filtration was advanced and the filtration life was improved as compared with Example 3.

(Example 5) As a band-shaped short fiber nonwoven fabric,
A sheath-core composite fiber having a composite ratio of 5: 5 using a linear low-density polyethylene (melting point: 125 ° C.) on the sheath side and polypropylene on the core side, a basis weight of 32.6 g / m ² , a thickness of 0.30 mm,
A nonwoven fabric having a fiber diameter of 23 μm, a slit width of 5 cm, and a fiber intersection point thermally bonded by a heat-through-air heat treatment machine was used. In addition, the injection molded product made of polypropylene of Example 1 was used as the perforated cylindrical body. First, the band-shaped short fiber nonwoven fabric is passed through a group of fold forming guides having the structure shown in FIG. 7, and then twisted 200 times per meter by a twisting machine, and then wound around a bobbin to obtain 16 folds and voids. A band-like short fiber nonwoven fabric bundle having a rate of 87% was formed. Next, the band-shaped short fiber bundle is unwound from the bobbin, and the winder is used to rotate the spindle at 1000 rpm, and the outer diameter is 62 m.
m to obtain a cylindrical filter cartridge having a yarn interval of 0.3 mm and a porosity of the filtration layer of 77%. Table 1 shows the measurement results of the filtration performance. Twisting reduced the porosity of the banded short fiber bundle, and tightly wound increased the filtration accuracy.

(Example 6) As a band-shaped short fiber nonwoven fabric,
A linear low-density polyethylene (melting point: 125 ° C.) is used on the sheath side, and 70% by weight of a sheath-core type composite fiber with a weight ratio of 5: 5 using polypropylene is used on the core side and 30% by weight of cotton.
/ M ² , a thickness of 0.29 mm, a fiber diameter of 21 μm, a slit width of 5 cm, and a nonwoven fabric whose fiber intersection was thermally bonded by a heat-through-air heat treatment machine was used. In addition, the injection molded product made of polypropylene of Example 1 was used as the perforated cylindrical body. First, the band-like short fiber nonwoven fabric was passed through a group of fold forming guides having the structure shown in FIG.
By twisting 00 times and winding around a bobbin, a band-shaped short fiber nonwoven fabric bundle having 16 folds and a porosity of 86% was formed. Next, a bundle of band-like short fibers is unwound from the bobbin, and the spindle speed is set to 1000 rpm by a winder.
In this way, a cylindrical filter cartridge having an outer diameter of 62 mm and a yarn interval of 0.2 mm and a porosity of the filtration layer of 76% was obtained. Table 1 shows the measurement results of the filtration performance. By mixing the cellulosic fiber cotton, hydrophilicity was increased, and water permeability was improved as compared with Example 5.

Comparative Example 1 A 2 mm diameter polypropylene spun yarn spun from a fiber having a fineness of 3 dtex was used in place of the band-shaped short fiber non-woven fabric bundle, and the spindle rotation speed was 10
At 00 rpm, an outer diameter of 62 m was formed in the same perforated cylindrical body as in Example 1.
m to obtain a cylindrical filter cartridge having a yarn interval of 1.0 mm and a porosity of the filtration layer of 77%. Table 1 shows the measurement results of the filtration performance. Although the water permeability and the filtration life were close to those of Example 1, the initial collection particle size was considerably large, and the collection particle size at 0.2 MPa was further increased, resulting in a filter inferior to that of Example 1. In addition, the drop of the filter medium was very large.

(Comparative Example 2) The short-fiber nonwoven fabric of Example 1
It was slit to a width of 5 cm, and wound around the same perforated tubular body as in Example 1 while applying a load of a linear pressure of 1 kg / cm to obtain a cylindrical filter cartridge having an outer diameter of 62 mm and a filtration layer porosity of 76%. Table 1 shows the measurement results of the filtration performance.
Although the initial collection particle size was slightly smaller than that of Example 1, water permeability and filtration life were inferior.

(Comparative Example 3) One type of filter paper specified in JIS P 3801 cut to a width of 5 cm was used in place of the band-like short fiber nonwoven fabric bundle. First, this band of filter paper,
While passing through a metal funnel having an inlet diameter of cm and an outlet diameter of 0.5 cm, twisting was performed 200 times per meter and then wound around a bobbin. Next, the twisted filter paper is unwound from the bobbin and wound around a perforated cylindrical body at a spindle rotation speed of 1000 rpm until the outer diameter becomes 62 mm.
m, a cylindrical filter cartridge having a filtration layer porosity of 73% was obtained. Table 1 shows the measurement results of the filtration performance. Example 5
The initial pressure loss was larger and the filtration life was inferior. In addition, the filter medium was slightly dropped.

[0057]

The filter cartridge of the present invention can capture fine particles, has a long filtration life, hardly changes the initial collection particle size, and has a low pressure loss, as compared with the conventional thread wound filter cartridge. Things are obtained. In addition, when a pleated material of a band-shaped long-fiber nonwoven fabric that is bundled so that at least a part of the fold is non-parallel is used, the folds and the folds in the vertical direction can be compared with the pleated materials having parallel folds. Since the pressure is not easily received, the filtration performance can be stably maintained without the folds being crushed.

[Brief description of the drawings]

FIG. 1 is a drawing of a nonwoven fabric laminated filter cartridge formed by winding a nonwoven fabric around a perforated cylindrical body.

FIG. 2 is a view showing a state in which a band-shaped short fiber nonwoven fabric is processed into a pleated material by a pleated guide.

FIG. 3 is a cross-sectional view showing an example of a fold forming guide used in the present invention.

FIG. 4 is a cross-sectional view showing an example of a fold forming guide used in the present invention.

FIG. 5 is an explanatory diagram showing an example of a cross-sectional shape of a non-parallel pleat.

FIG. 6 is an explanatory diagram showing an example of a cross-sectional shape of a pleated parallel fold.

FIG. 7 is a view showing an example of a comb-shaped fold forming guide, a narrow rectangular guide, and a small diameter guide used in the present invention.

FIG. 8 is a partially cutaway perspective view illustrating a cross-sectional area of a pleated object according to the present invention.

FIG. 9 is an explanatory diagram of a method of forming a filter cartridge.

FIG. 10 is a perspective view of a filter cartridge according to the present invention.

FIG. 11 is a perspective view of a filter cartridge in which a nonwoven fabric according to the present invention is wound.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wide nonwoven fabric 2 Strip short fiber nonwoven fabric 3 External regulation guide 4 Internal regulation guide 5 Fold formation guide 6 Small hole guide 7 Folded or band-shaped short fiber nonwoven fabric bundle 8 Comb-shaped fold formation guide 9 Narrow rectangular guide 10 Strip short fiber Oval of minimum area containing non-woven fabric bundle 11 Traverse guide 12 Spindle 13 Perforated tubular body 14 Filter cartridge 15 Outermost band-like short fiber non-woven fabric bundle and strip short wound in parallel with the next lower layer 16: Inner layer 17: Inserted nonwoven layer 18: Outer layer

Claims (14)

[Claims] 1. A filter cartridge comprising a band-shaped short-fiber nonwoven fabric containing thermoplastic fibers and having at least a part of the fiber intersections bonded thereto, being wound around a perforated cylindrical body in a twill shape. 2. The filter cartridge according to claim 1, wherein the band-shaped short-fiber nonwoven fabric is a nonwoven fabric mixed with another fiber containing at least 30% by weight of a thermoplastic fiber. 3. The heat-bondable conjugate fiber in which the thermoplastic fibers constituting the band-shaped short-fiber nonwoven fabric are composed of a low-melting-point resin and a high-melting-point resin, and the difference between the melting points of the two resins is 10 ° C. or more. Or the filter cartridge according to 2. 4. The low-melting resin is selected from linear low-density polyethylene, low-density polyethylene, high-density polyethylene, polypropylene, a copolymer of propylene with another α-olefin, and a low-melting polyester. The filter cartridge according to claim 3, which is a resin. 5. The high melting point resin is a high density polyethylene,
The filter cartridge according to claim 3, wherein the filter cartridge is a resin selected from the group consisting of polypropylene, a copolymer of propylene and another α-olefin, and polyethylene terephthalate. 6. The filter cartridge according to claim 1, wherein said band-shaped short-fiber nonwoven fabric is subjected to embossing thermocompression bonding. 7. The filter cartridge according to claim 1, wherein the fiber intersections of the band-shaped short-fiber nonwoven fabric are heat-sealed. 8. The filter cartridge according to claim 1, wherein a twist is added to the band-shaped short fiber nonwoven fabric. 9. The filter cartridge according to claim 1, wherein the band-shaped short fiber nonwoven fabric is a pleated material having 4 to 50 folds, and is wound around a perforated cylindrical body in a twill shape. 10. The filter cartridge according to claim 9, wherein at least a portion of the folds of the fold are non-parallel. 11. The filter cartridge according to claim 1, wherein the porosity of the pleated material is 60 to 95%. 12. The filter cartridge according to claim 1, wherein the porosity of the filter cartridge is 65 to 85%. 13. The filter cartridge according to claim 1, wherein the porosity of the filter cartridge increases from the inner layer to the outer layer.
5. The filter cartridge according to any one of 5. 14. The width of the band-shaped short fiber nonwoven fabric is 0.5 cm.
The product of the width (cm) and the basis weight (g / m ² ) is 20
The filter cartridge according to claim 1, wherein the value is 0 or less.