JP2001321622A - Filter cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter cartridge in which the shortages of filtration life and water permeability or the generation of the materials loosened from the filter cartridge, which are the problems of the usual filter cartridge, are prevented. SOLUTION: This filter cartridge is obtained by winding a belt-like nonwoven fabric consisting of a thermoplastic fiber around a perforated cylindrical body in a twilled state. When the belt-like nonwoven fabric is wound in the twilled state, the winding number (W) of times necessary for winding the fabric around the cylindrical body from one end of the cylindrical body to the other end is made to be one to ten per 250 mm length of the cylindrical body. It is more preferable that the number (W) is selected from the numbers the denominators of which are 4-40 when the W-doubled numerical value (2W) is approximated to an irreducible fraction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylindrical filter cartridge for liquid filtration.

[0002]

2. Description of the Related Art At present, various filters have been developed and produced for purifying fluids. Above all, cylindrical cartridge type filters (hereinafter referred to as filter cartridges), in which filter media can be easily replaced, are used to remove suspended particles in industrial liquid raw materials, remove cake flowing out of a cake filtration device, purify industrial water, etc. Used in a wide range of industrial fields.

Several types of filter cartridges have been proposed. The most typical one is a wound filter cartridge utilizing spun yarn. This is a cylindrical filter cartridge made by winding a spun yarn, which is the material of the filter medium, in a twill shape around a perforated cylindrical core, and then fluffing the spun yarn. It's being used.

[0004] Such a conventional method of collecting foreign matter of a thread-wound filter cartridge involves collecting foreign matter with fluff generated from a spun yarn and entangling the foreign matter in a gap between the spun yarns. Since it is difficult to adjust the size and shape of the fluff and the gap, there is a disadvantage that the size and amount of foreign matter that can be collected are limited. Further, since the spun yarn is made from short fibers, there is a disadvantage that constituent fluids of the spun yarn fall off when a fluid flows through the filter cartridge. Further, since spun yarn is produced by spinning short fibers, at least two steps of spinning and spinning of short fibers are required, and as a result, the price may be increased.

Several proposals have been made to solve the drawbacks of the wound filter cartridge using spun yarn. For example, JP-A-51-3
Japanese Patent No. 4469 discloses a method in which a fibrous sliver is used in place of a spun yarn and is thermally cured with a curing agent such as a urea resin. However, this method aims at improving the particle collection performance of the filter, and does not solve the above-mentioned problem.

Japanese Utility Model Application Laid-Open No. 54-36878 discloses a filter using a tape-like cellulose-based nonwoven fabric instead of a spun yarn, which has no danger of binder elution and has low material and production costs. It has been disclosed. However, this method does not solve the above-mentioned problem.

Further, Japanese Utility Model Publication No. 6-7767 discloses a filter material in which a porous tape-shaped paper is squeezed and squeezed while being twisted, and the diameter of which is regulated to about 3 mm. There has been proposed a filter cartridge in a form wound closely. This filter cartridge has a feature that the winding pitch of the winding can be increased toward the outside of the porous inner cylinder.
However, it is necessary to squeeze and squeeze the filtration material, and therefore, the collection of foreign matter is mainly performed between the winding pitches of the filtration material. Therefore, the thread-wound type filter using a conventional spun yarn collects foreign matter with its fluff. As described above, it is difficult to expect foreign matter collection by the filtration material itself. As a result, the filter may be clogged on the surface and the filtration life may be shortened, or the liquid permeability may be poor.

A similar invention is disclosed in Japanese Patent Publication No. 1-256.
No. 07, Japanese Utility Model Publication No. 3-52090,
Although these are disclosed in Japanese Patent No. 317513, they are intended to improve water absorption, oil absorption, antibacterial properties, etc., and do not solve the above-mentioned problems.

[0009] In addition, Japanese Patent Application Laid-Open No. 1-145423 discloses that a cellulose spunbond nonwoven fabric is cut into a band-like body through a bobbin having a large number of fine holes, passed through a narrow hole, and twisted to form a string. A wound filter has been proposed. This filter is considered to have higher mechanical strength than a conventional roll tissue filter in which α-cellulose obtained by purifying softwood pulp is made into thin paper and wound in a roll shape, and it is considered that there is no dissolution by water or elution of a binder. However, the cellulose spunbond non-woven fabric used for this filter has a paper-like form, so its rigidity is too large and it is easy to swell in liquid, and the swelling causes a decrease in filter strength, a change in filtration accuracy, and liquid permeability. There is a possibility that various problems such as deterioration of filtration and reduction of filtration life may occur. In addition, the bonding of fiber intersections is often performed by chemical treatment or the like, but the bonding is often insufficient, causing a change in filtration accuracy or a drop of fiber waste. In many cases, it is difficult to obtain stable filtration performance.

[0010] Japanese Patent Application Laid-Open No. 4-45810 discloses that
A slit nonwoven fabric made of a composite fiber in which 10% by weight or more of the constituent fibers is divided into 0.5 denier or less is wound around a porous core tube so that the fiber density becomes 0.18 to 0.30 g / cm ^3. Filters have been proposed. This filter has 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. In addition, since the strength of the nonwoven fabric may be reduced due to uneven division, the strength of the manufactured filter is reduced and it is easy to deform during use, or the porosity of the filter changes and the liquid permeability decreases there's a possibility that. A similar patent is disclosed in
-45811, Japanese Utility Model Laid-Open No. 4-131412,
Japanese Utility Model Laid-Open No. 4-131413, Japanese Utility Model Laid-Open No. 5-2715, and Japanese Utility Model Laid-Open No. 5-18614 all use split fibers and do not solve the above-mentioned problems.

Further, US Pat. No. 6,054,216 discloses that a melt-blown non-woven fabric having a width of 2.5 to 16 cm and a fiber diameter of 0.5 to 10 μm is twisted and wound around a reinforcing cord to form a cord. Discloses a method of manufacturing a filter cartridge in which a filter cartridge is wound in a twill pattern. In this method, the melt-blown non-woven fabric is simply twisted to the reinforcing cord, so when the flow rate of the liquid to be filtered is high, the reinforcing cord and the melt-blown non-woven fabric may be separated, or the twist of the melt-blown non-woven fabric may loosen and the filtration accuracy may change. Therefore, it is considered difficult to maintain a constant filtration ability.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a filter cartridge which prevents a problem with a conventional filter cartridge, that is, a shortage of filtration life and water permeability, or the occurrence of falling off from the filter cartridge. Is to do.

[0013]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that when manufacturing a filter cartridge in which a band-shaped nonwoven fabric containing thermoplastic fibers is wound in a twill shape into a cylindrical shape, The above problem was solved by setting the number of winds to a specific value, and it was found that a filter cartridge having particularly excellent filtration performance was obtained, and the present invention was completed.

The present invention has the following configuration. (1) A filter cartridge in which a band-shaped nonwoven fabric made of thermoplastic fiber is wound in a twill shape around a perforated tubular body. Number of windings from one end to the other (W)
Is 1 to 10 times per 250 mm length of the perforated tubular body

(2) When the numerical value (2W) that is twice the number of times of winding (W) is represented by the closest approximation that has a denominator of two digits or less and is not reduced, the denominator of the fraction is 4 to 40.
The filter cartridge according to the above (1), wherein

(3) The width of the belt-shaped nonwoven fabric is 0.5 cm to 40 cm.
cm. The filter cartridge according to the above item (1) or (2), wherein

(4) The width (cm) and the basis weight (g) of the belt-shaped nonwoven fabric
/ M ² ) is from 20 to 200 (1) to (3).
Item 7. The filter cartridge according to any one of the above items.

(5) The filter cartridge according to any one of the above (1) to (4), wherein the belt-shaped nonwoven fabric is a long-fiber nonwoven fabric in which at least a part of the fiber intersections is thermally bonded.

(6) The filter cartridge according to the above (5), wherein the long-fiber nonwoven fabric is a long-fiber nonwoven fabric made by a spunbond method.

(7) The filter cartridge according to any one of the above (1) to (4), wherein the band-shaped nonwoven fabric is a meltblown nonwoven fabric.

(8) The above-mentioned (1) to (4), wherein the belt-shaped nonwoven fabric is a nonwoven fabric obtained by laminating at least two layers of a long-fiber nonwoven fabric having at least a part of the fiber intersection points thermally bonded thereto and a melt-blown nonwoven fabric. The filter cartridge according to any one of the above.

(9) The filter cartridge according to any one of the above (1) to (8), wherein the porosity of the filter medium of the filter cartridge is 65 to 85%.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. The filter cartridge of the present invention is a filter cartridge obtained by winding a belt-shaped nonwoven fabric made of thermoplastic fiber around a perforated tubular body in a twill shape. In the present invention, the band-shaped nonwoven fabric is a narrow nonwoven fabric, which is obtained by slitting (cutting) a wide nonwoven fabric, or a nonwoven fabric directly manufactured with a narrow width. In order to obtain stable quality at low cost, it is preferable to slit a wide range of nonwoven fabric. The optimum width and basis weight of the nonwoven fabric used will be described later.

In the present invention, the thermoplastic fiber is a fiber made of a thermoplastic resin. As the thermoplastic fiber used in the present invention, any thermoplastic resin that can be melt-spun can be used. Examples of the thermoplastic resin, polypropylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, copolymerized polypropylene (for example, mainly propylene, ethylene,
Polyolefin-based resins such as binary or multi-component copolymers with butene-1,4-methylpentene-1, etc., polyethylene terephthalate, polybutylene terephthalate, and acid components in addition to terephthalic acid and isophthalic acid. Polyester resins such as these copolymerized low melting point polyesters, nylon 6, nylon 6
6, polyamide-based resin, polystyrene (atactic polystyrene, syndiotactic polystyrene), polyurethane elastomer, polyester elastomer,
A thermoplastic resin such as polytetrafluoroethylene can be presented.

It is also possible to use a functional resin such as a filter cartridge having biodegradability by using a biodegradable resin such as a lactic acid-based polyester. Also,
If a resin polymerized with a metallocene catalyst such as polyolefin resin or polystyrene is used for the filter cartridge, effects such as improvement in nonwoven fabric strength, improvement in chemical resistance, and reduction in production energy can be expected. These resins may be blended and used to adjust the thermal adhesiveness and rigidity of the nonwoven fabric. Among these, polyolefin resins such as polypropylene are preferable from the viewpoint of chemical resistance and price when the filter cartridge is used for filtration of an aqueous liquid at room temperature, and when used for a relatively high temperature liquid. Polyester-based resins, polyamide-based resins, syndiotactic polystyrene and the like are preferred.

In the present invention, as the constituent fibers of the band-shaped nonwoven fabric, other than the thermoplastic fibers, as long as the functions of the filter cartridge of the present invention such as filtration life, water permeability, and the function of preventing falling off from the filter cartridge are not impaired. , For example, cotton, glass fiber and metal fiber.

In the present invention, the bonding method of the fiber intersections for forming the nonwoven fabric from the thermoplastic fibers is not particularly limited, but it is preferable to use a thermal bonding method. As a method of thermal bonding of the fiber intersection of the thermoplastic fibers used in the present invention,
Examples include a method of thermocompression bonding using a device such as a hot embossing roll and a hot flat calender roll, and a method of using a heat treatment machine such as a hot air circulation type, a heat through air type, an infrared heater type, and a vertical hot air jet type. it can. Among them, a method using a hot embossing roll is preferable because the production speed of the nonwoven fabric can be improved, the productivity is good, and the cost can be reduced.

Further, the nonwoven fabric made by the method using the hot embossing roll has a portion having strong thermocompression bonding by an emboss pattern and a portion having only weak thermocompression bonding by deviating from the emboss pattern. As a result, the obtained filter cartridge can collect a large amount of foreign matter in a portion where strong thermocompression bonding is performed. on the other hand,
Part of the foreign matter is collected in the part with only weak thermocompression bonding, but the remaining foreign matter passes through the nonwoven fabric. Since it is possible to move to the next layer, a deep filtration structure utilizing the inside of the filter medium is preferable. In this case, it is desirable that the area of the emboss pattern is 5 to 25%. By setting the area to 5% or more, the effect of the thermal bonding at the fiber intersection as described above can be improved, and by setting the area to 25% or less, it is possible to suppress the rigidity of the nonwoven fabric from becoming too large. Alternatively, it is possible to make it easier for the foreign matter to pass through the nonwoven fabric to some extent, and to catch the foreign matter that has passed inside the filter cartridge, thereby extending the life of the filter cartridge.

The thermoplastic fiber is more preferably 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, because the thermal adhesion of the band-shaped nonwoven fabric is improved. There is no particular upper limit for the melting point difference, but among the thermoplastic resins that can be melt-spun, the temperature difference between the highest melting point resin and the lowest melting point resin corresponds. In the case of a resin having no clear melting point, the flow start temperature is regarded as the melting point. When a composite fiber made of a low-melting resin and a high-melting resin is used as the fiber constituting the band-shaped nonwoven fabric, the degree of thermal bonding can be easily adjusted, and thus the porosity at the end of the filter cartridge can be easily adjusted.

The combination of the low melting point resin and the high melting point resin of the composite fiber is not particularly limited as long as the difference in melting point is at least 10 ° C., preferably at least 15 ° C., for example, linear low density polyethylene / polypropylene, high density polyethylene. /
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 / thermoplastic polyester, polypropylene / Thermoplastic polyester, copolymerized polyester / thermoplastic polyester, various types of polyethylene / nylon 6, polypropylene / nylon 6, nylon 6 / nylon 66, nylon 6 / thermoplastic polyester.

Of these, the use of a combination of linear low-density polyethylene / polypropylene is preferred because the rigidity and porosity of the nonwoven fabric and the end of the filter cartridge can be easily adjusted. When the obtained filter cartridge is used for filtering a relatively high-temperature liquid, a low-melting polyester / polyethylene terephthalate combination obtained by copolymerizing an acid component with isophthalic acid in addition to terephthalic acid is also preferably used. Can be.

In the present invention, the perforated tubular body serves as a core material of the filter cartridge, and its material and shape have strength enough to withstand an external pressure during filtration.
There is no particular limitation as long as the pressure loss is not extremely high, and for example, an injection molded product obtained by processing polyethylene or polypropylene into a net-like cylindrical shape, such as a core material used in a normal filter cartridge, or Alternatively, ceramic or stainless steel may be processed in the same manner. Alternatively, another filter cartridge such as a fold-folded filter cartridge or a non-woven fabric wound type filter cartridge may be used as a perforated cylindrical body.

Next, a method of winding the band-shaped nonwoven fabric around the perforated cylindrical body will be described. FIG. 2 shows an example of the manufacturing method. The winder used for a normal thread-wound filter cartridge can be used for the winding machine. The bobbin 5 of this winder has a diameter of about 10 to 40 mm and a length of 100 to
A perforated tubular body 2 of about 1000 mm is mounted, and a band-shaped nonwoven fabric 4 converged through the thread path of a winder and a hole of a traverse guide 6 is wound around the perforated tubular body for about one to two turns.
The perforated tubular body and the end portion of the belt-shaped nonwoven fabric may be bonded by heat bonding or the like in order to reliably perform winding. Since the yarn path of the winder is traversed in the A and B directions by a traverse guide 6 installed in parallel with the bobbin, the belt-shaped nonwoven fabric is wound around the perforated tubular body in a twill shape by the rotation of the bobbin. The diameter of the hole provided in the traverse guide 6 depends on the basis weight and width of the band-shaped nonwoven fabric to be used, but is 3 mm to 10 mm.
Is preferable. If the diameter is less than 3 mm, the friction between the band-shaped nonwoven fabric and the holes increases, and the winding tension becomes too high. If this value exceeds 10 mm, the convergence size of the band-shaped nonwoven fabric becomes unstable.

The winding condition of the band-shaped nonwoven fabric may be set in accordance with the usual manufacturing process of the thread-wound filter cartridge. For example, the initial speed of the bobbin is set at 1000 to 2000 rpm.
The winding may be performed while adjusting the feeding speed and applying an appropriate tension. The porosity of the filter cartridge can also be changed by the tension at this time.

The filtration accuracy is adjusted by adjusting the ratio of the traverse guide traversing speed to the bobbin rotation speed so that the band-shaped nonwoven fabric is wound in the lengthwise direction when the band-shaped nonwoven fabric is wound in a twill shape. Can be changed by changing the number of windings from one end to the other end (hereinafter, referred to as the number of winds and represented by W). That is, the wind number (hereinafter referred to as W) refers to the number of rotations of the bobbin 5 until the traverse guide 6 moves from one end to the other end in the length direction of the perforated tubular body 2. For this reason, the value of W is not always a natural number. Wind numbers need to be very accurate,
The movement amount of the traverse guide and the rotation speed of the bobbin need to be linked by a gear or the like so that this value is not deviated.

In the filter cartridge of the present invention, the value of the number of winds W is 1 to 10 times, preferably 2 to 8 times, more preferably 3 to 8 times per 250 mm of the perforated cylindrical body used for the filter cartridge. 5 times. If this value is less than one time, the angle of the traverse becomes too large, so that the band-shaped nonwoven fabric tends to come off from the perforated cylindrical body. Conversely, if this value exceeds 10, the traverse angle becomes too small, and in this case also, the band-shaped nonwoven fabric is likely to come off the perforated tubular body.

In the case of a wind filter using a spun yarn as a material for the filter medium, the relationship between the number of winds and the filter accuracy is well known. In a conventional wind filter using a spun yarn, the cross-sectional shape of a yarn to be wound (that is, a spun yarn) is generally close to a circle, and the diameter of the yarn is at most about 3 mm. Therefore, the number of windings and the yarn pitch when wound in a twill pattern can be expressed by the following equations (1) and (2). 2 × W = 2 × W ₀ ± 1 / N Equation (1) N = T / W ₀ / P Formula (2)

[0038] In this case, W is the number of winding, W ₀ is a natural number that approximates to the winding number W, N are aligned number, T is the traverse width, P is the pitch of the thread. Of the variables, W ₀ and N are natural numbers, and W, P, and T are arbitrary positive numbers. Generally, the smaller the pitch of the yarn, the finer the wind filter becomes. This formula can also be applied to yarns other than spun yarn, for example, split yarns.

On the other hand, in the filter cartridge of the present invention, since a band-shaped nonwoven fabric is used instead of a spun yarn as a material for the filter medium, the expressions (1) and (2) cannot be applied as they are. Because, as described above, when the nonwoven fabric is wound, the nonwoven fabric converges, and the thickness of the yarn becomes much larger than that of a normal spun yarn.
Even if the conditions (2) and (3) are satisfied, the yarns overlap with each other, and a filter cartridge with the desired accuracy cannot be obtained.

The present inventors have conducted intensive studies and have found that a filter cartridge formed by winding a band-shaped nonwoven fabric around a perforated cylindrical body in a twill shape has a denominator M when the number of winds is approximated by the following equation (3). It has been found that when _n takes a certain value, it exhibits excellent filtration performance. 2 × W ≒ X / M _n formula (3) (where X and M _n are a combination of natural numbers having no common divisor, and n represents the maximum number of digits. For example, M ₂ is 1
Is an integer of ~ 99)

In the present invention, M ₂ of the equation (3), that is, a numerical value (2W) that is twice the number of winds W, is calculated by setting the denominator to 2
It is desirable that the numerical value of the denominator when represented by the closest fraction that is not more than one digit and is not reduced is 4 to 40, preferably 5 to 20. The value of M ₂ is a fine filter cartridge larger. If this value is less than 4,
The eyes of the resulting filter cartridge are too coarse,
In addition, the state of the filter cartridge end face may not be smooth. On the other hand, when the value of M ₂ exceeds 40,
There is a possibility that the filter cartridge becomes too fine and the liquid permeability is reduced, or the filtration life is shortened.

What is important here is that the value of 2W is approximated to a fraction whose denominator is a natural number of two digits or less. For example, when the wind number W is 1.893, 2 × W is 3.7.
86. If this 3.786 is the closest approximation with a single-digit fraction in the denominator, it is 34/5 (this display means a mixed fraction consisting of 3 and 4/5, and the same applies hereinafter unless otherwise specified). Become. Therefore, if the wind number W is 1.893, M ₁ is 5 which is a denominator of 3 4/5. Similarly, when 2W is closest approximated by a fraction with a denominator of two digits or less, its value is 3 11/14, so M ₂ is 3 11/1
It is 14 which is the denominator of 4. Similarly, when 2W is the closest approximation with a fraction whose denominator is 3 digits or less, it becomes 3393/500, so M ₃ is 500. Therefore, in this case, the value of M ₂ in Expression (3) is 14, which is the denominator when the denominator is approximated by a two-digit fraction. In the case where the denominator is the closest approximation to 2W with a fraction having two digits or less, 3 22/28, 3 33/4
2 mag is also the closest approximation, but these numbers are reduced to 3
Since it is 11/14, the value of M ₂ in this case is 14.

By changing the value of M ₂ in the range of 4 to 40 in accordance with the desired accuracy, filter cartridges of various accuracy can be manufactured even with the same band-shaped nonwoven fabric. Further, it can be combined with a method of changing the width or the basis weight of the band-shaped nonwoven fabric, or changing the fiber diameter of the band-shaped nonwoven fabric. Also, M ₂
Wound until to the value to a value a certain outside diameter, continued by winding by increasing the value of M _2, it is also possible to further optimize the depth filtration structure of the filter cartridge.

The filter cartridge of the present invention is obtained by winding a band-shaped nonwoven fabric to an outer diameter of about 1.5 to 3 times the outer diameter of the perforated tubular body 2 with the number of winds determined as described above. Shape. The interval between the band-shaped nonwoven fabrics changes depending on the outer diameter of the perforated tubular body 2 even when wound with the same number of windings. However, the outer diameter of the perforated tubular body 2 is usually determined by the use condition. In many cases, the filtration performance is not adjusted by the outer diameter of the perforated cylindrical body 2. The initial collection particle size of the filter cartridge is
If the number of winds is the same, the filter cartridge becomes smaller as the outer diameter of the filter cartridge becomes larger.

In the present invention, the width of the band-shaped nonwoven fabric varies depending on the basis weight of the nonwoven fabric to be used.
0 cm is preferred. If the width of the band-shaped non-woven fabric is less than 0.5 cm, the non-woven fabric may be cut, and it is difficult to adjust the tension when winding the band-shaped non-woven fabric in a twill shape. , The winding time becomes longer and the productivity decreases. If the width of the band-shaped nonwoven fabric exceeds 40 cm, friction on the yarn path of a winder such as a traverse guide increases, or the size of the converged nonwoven fabric tends to be uneven.

The basis weight of the band-shaped nonwoven fabric, that is, the weight per unit area of the nonwoven fabric is preferably from 5 to 200 g / m ² . When the basis weight is less than 5 g / m ² , the amount of fibers is reduced, so that the unevenness of the nonwoven fabric is increased, the strength of the nonwoven fabric is reduced, or the heat bonding at the fiber intersection may be difficult. On the other hand, the basis weight is 200 g / m
^If it exceeds ² , the rigidity of the band-shaped nonwoven fabric becomes too large, and it becomes difficult to wind the band-shaped nonwoven fabric around the perforated tubular body in a twill shape.

The upper limit of the width of the band-shaped nonwoven fabric varies depending on the basis weight, and the product of the width (cm) of the band-shaped nonwoven fabric and the basis weight (g / m ² ) is preferably ^{20 to} 200 cm · g / m ² . When this value exceeds 200 cm · g / m ² , the rigidity of the band-shaped nonwoven fabric becomes too large, and it is difficult to wind it around the perforated tubular body in a twill shape. It becomes difficult. On the other hand, if the product is 2
If it is less than 0 cm · g / m ² , the nonwoven fabric may be cut.

The band-shaped nonwoven fabric used in the filter cartridge of the present invention is preferably a long-fiber nonwoven fabric, a melt-blown nonwoven fabric, or a laminated nonwoven fabric thereof, in which at least a part of the fiber intersections is thermally bonded. Among these, a long-fiber nonwoven fabric in which at least a part of the fiber intersection is thermally bonded is preferable.

As the long-fiber nonwoven fabric, a nonwoven fabric obtained by a spunbonding method is particularly preferable. The spun bond method is a nonwoven fabric manufacturing technique in which thermoplastic fibers discharged from a nozzle are drawn by suction using an air gun or the like, spread on a conveyor, and then thermally bonded. As shown in FIG. 3, the long fiber nonwoven fabric made of a thermoplastic resin obtained by the spunbonding method has the fiber direction aligned with the machine direction, so that the holes constituted by the fibers 8 are elongated, and the fiber The maximum passing particles 7 of the filter cartridge to be used are small. On the other hand, in the case of a non-woven fabric made of short fibers obtained by the card method or the like, the fiber direction is not constant as shown in FIG. Even if the fiber diameter and the porosity are the same as those of the long-fiber nonwoven fabric produced by the bonding method or the like, the maximum passage particle diameter 7 of the filter cartridge obtained by using the same becomes large.

Since the water permeability of the filter medium of the filter cartridge is substantially determined by the porosity if the fiber diameter is the same, a filter cartridge having excellent water permeability can be obtained by using a long-fiber nonwoven fabric made by a spunbond method or the like. It is done. This effect is reduced when a binder that closes the pores of the filter medium, such as an adhesive, is used. Therefore, the use of a cellulose spunbond nonwoven fabric is not preferable. In addition, the use of a cellulose spunbonded nonwoven fabric reduces the strength of the nonwoven fabric. Therefore, when the filtration pressure is increased due to clogging of a filter or the like, there is a problem that pores formed of fibers are easily deformed.

The average fiber diameter of the long fibers used in the long-fiber nonwoven fabric varies depending on the use of the filter cartridge and the type of the resin, and therefore, it is difficult to specify the average fiber diameter.
80 μm is desirable. When the average fiber diameter exceeds 680 μm, there is no difference from a case where a continuous yarn is simply bundled, and there is no point in using a long-fiber nonwoven fabric. Further, by setting the average fiber diameter to 9 μm or more, sufficient strength of the nonwoven fabric can be obtained, and the strength of the manufactured filter cartridge increases, which is preferable. In addition, when spinning a fiber having an average fiber diameter of less than 9 μm by the current spunbond method, the workability and spinnability of the nozzle used are deteriorated, and as a result, the price of the manufactured spunbond nonwoven fabric increases. Sometimes.

The constituent fibers of the long-fiber nonwoven fabric do not necessarily have to have a circular cross-section, and a yarn having an irregular cross-section may be used. In that case, the collection of the fine particles increases as the surface area of the filter increases, so that a filter cartridge having the same liquid permeability and high precision can be manufactured as compared with the case where a fiber having a circular cross section is used.

The above-mentioned method is used as the thermal bonding method at the fiber intersection of the long-fiber nonwoven fabric. Among them, the method using a hot embossing roll can improve the production speed of the nonwoven fabric, has high productivity, and reduces cost. It is preferable because it can be inexpensive. As shown in FIG. 5, the long-fiber nonwoven fabric made by the method using the hot embossing roll has a portion 10 having strong thermocompression bonding by an embossed pattern and a portion 11 having only weak thermocompression bonding by deviating from the embossing pattern. And exists. As a result, a large number of foreign substances 12 and 13 can be collected in the portion 10 where there is strong thermocompression bonding. On the other hand, in the portion 11 where the fiber intersection is hardly bonded by heat, a part of the foreign matter is collected, but the remaining foreign matter passes through the long-fiber nonwoven fabric. Since it is possible to move to the next layer, a deep filtration structure utilizing the inside of the filter medium is preferable.

In the filter cartridge of the present invention, a melt-blown non-woven fabric can be used as the belt-shaped non-woven fabric. Since the melt-blown nonwoven fabric has a finer fineness than the long-fiber nonwoven fabric and can easily form a uniform formation, the filtration accuracy of the obtained filter cartridge can be increased. The average fiber diameter of the fibers of the melt-blown nonwoven fabric varies depending on the use of the filter cartridge and the type of the resin, but is desirably 0.5 to 1000 μm, preferably 1 to 50 μm. Average fiber diameter is 0.5
If it is less than μm, the nonwoven fabric is difficult to manufacture, and the cost of the obtained filter cartridge may increase,
If the average fiber diameter exceeds 1000 μm, the formation of the nonwoven fabric, which can broaden the fiber diameter distribution, becomes poor. If the average fiber diameter exceeds 50 μm, adjacent fibers may adhere to each other with residual heat. However, there is no particular problem as long as the effect of the present invention is not impaired.

In the filter cartridge of the present invention, a nonwoven fabric obtained by laminating at least two layers of the long-fiber nonwoven fabric and the meltblown nonwoven fabric may be used as the belt-like nonwoven fabric. In this case, the advantages of the long-fiber nonwoven fabric and the melt-blown nonwoven fabric can be used together. In this case, the particle collecting performance of the filter cartridge is greatly affected by the fiber diameter of the melt-blown nonwoven fabric, and is particularly preferable when the filter cartridge has high accuracy.

In the filter cartridge of the present invention, split fibers can be used as the fibers of the band-shaped nonwoven fabric. However, as described above, it is actually difficult to split the split fibers uniformly, so that the average fiber diameter is small. It is more preferable to use a close melt blown nonwoven fabric or the like.

When a hydrophilic resin such as polyvinyl alcohol is mixed with the raw material resin of the band-shaped nonwoven fabric or the surface of the band-shaped nonwoven fabric is hydrophilized, the obtained filter cartridge is filtered with an aqueous solution or the like. When used for filtration, the liquid permeability is improved. Therefore, when filtering an aqueous solution or the like, a filter cartridge using such a resin is preferable.

The porosity of the filter cartridge of the present invention is preferably in the range of 65 to 85%. If the porosity is less than 65%, the fiber density becomes too high, and the liquid permeability decreases. Conversely, if the porosity exceeds 85%, the strength of the filter cartridge is reduced, and problems such as deformation of the filter cartridge when the filtration pressure is high are likely to occur.

In the present invention, it is preferable that the end face of the filter cartridge is smoothed by thermal bonding or the like, since a smooth end face sealing portion is formed at both ends of the filter cartridge, so that the sealing property is improved. After the band-shaped nonwoven fabric forming both end portions of the filter cartridge is melted by heat, a solvent, ultrasonic waves, or the like, it is smoothed by solidifying while shaping it into a smooth end face. In the present invention, since a belt-shaped nonwoven fabric made of thermoplastic fibers is used, a method using heat is preferable.

[0060]

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 winder described below was used, and the evaluation of physical properties, filtration performance, and the like of the nonwoven fabric and the filter cartridge used for evaluation was performed by the methods described below.

(Winder and Number of Winders) A winder having a traverse width (traverse width) of 250 mm and a hole diameter of a traverse guide (6 in FIG. 2) of 5 mm was used. The initial speed of the bobbin was set at 1500 rpm. The number of winds (W), that is, the number of times the belt-shaped nonwoven fabric is wound from one end of the perforated cylindrical body to the other end, is determined by the reciprocating motion of the traverse guide and the rotational motion of the perforated cylindrical body. Adjusted by linking several sheets.

(Fabric Weight and Thickness of Non-Woven Fabric) A non-woven fabric was cut out from the non-woven fabric to be evaluated so as to have an area of 500 cm ^2, and its weight was measured and converted into a weight per 1 m ² (g). did. In addition, the thickness of the cut nonwoven fabric was arbitrarily measured at 12 points, and the average value of 10 points excluding the maximum value and the minimum value of the 12 points was defined as the thickness of the nonwoven fabric. The thickness of each point was measured under the conditions of a load of 196 Pa and a measuring speed of 2 mm / sec using "Digisic Nestester (trade name)" manufactured by Toyo Seiki Seisaku-sho, Ltd.

(Average Fiber Diameter of Non-Woven Fabric) Five places were randomly sampled from the non-woven fabric to be evaluated, photographed with a scanning electron microscope, and 20 fibers were randomly selected for each place. Was measured, and the average value was defined as the average fiber diameter (μm) of the nonwoven fabric.

(Porosity of Filter Media in Filter Cartridge) 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 the filter medium itself (the part where the perforated tubular body has been removed from the filter cartridge), the outer diameter of the perforated tubular body is used for the inner diameter value, and the weight value of the filter cartridge is used for the weight value. The value obtained by subtracting the weight of the perforated cylindrical body from the weight was used. (Apparent volume of filter medium) = π ｛(outer diameter of filter medium) ² − (inner diameter of filter medium) ² ｝ × (length of filter medium) / 4 (true volume of filter medium) = (weight of filter medium) / (raw material of filter medium) (Porosity of filter medium) = {1- (true volume of filter medium) / apparent volume of filter medium) × 100%

(Initial Collection Particle Size, Initial Pressure Drop) One filter cartridge was attached to the housing of the circulating filtration performance tester, and the flow rate was ³⁰ dm ^{3 /} min by a pump.
And water circulation. The pressure loss before and after the housing at this time was defined as the initial pressure loss. Next, add J
Seven types of test powder I (abbreviated as JIS type 7; median diameter: 27 to 31 μm) specified in IS Z 8901 were continuously added at a rate of 0.2 g / min per minute. The filtrate was collected, diluted at an appropriate magnification, and the number of particles contained in each liquid was measured using a light-blocking particle detector to calculate the initial collection efficiency. Further, by interpolating the value, a particle size showing a collection efficiency of 80% was obtained, and was set as an initial collection particle size.

(Modification of Filter Cartridge) One filter cartridge is attached to the housing (transparent) of the circulating filtration performance tester, and the flow rate is adjusted to ³⁰ dm ³ per minute by a pump to circulate water. A photograph of the appearance of the filter cartridge at this time was taken. Next, JIS 7 was added to the circulating water until the pressure loss before and after the housing became 0.5 MPa. Then, a photograph was taken of the external appearance of the filter cartridge when the pressure loss before and after the housing became 0.5 MPa under the same conditions (shooting distance, magnification, etc.) as before. Then, the outer diameter of the filter cartridge shown in the two photographs is measured by image analysis, and those having a shrinkage of less than 10% are evaluated as ○; It was judged as x.

Example 1 As a nonwoven fabric, a polypropylene long-fiber nonwoven fabric obtained by a spun bond method was used. The fiber intersection was thermally bonded by a thermocompression bonding method using a hot embossing roll. The basis weight is 22g
/ M ² , the thickness was 200 μm, and the average fiber diameter was 17 μm. The long fiber nonwoven fabric was slit into a width of 50 mm to obtain a belt-shaped nonwoven fabric. In addition, as a perforated cylindrical body, the inner diameter is 30 m.
m, an outer diameter of 34 mm, a length of 250 mm, and an injection-molded product made of polypropylene having 180 holes of 6 mm square were used. Also, the number of winds in the winder (W)
Was set to 3.1875. (In this case, M in equation (3)
₂ becomes 8. ) Then, the band-shaped nonwoven fabric was converged through the holes of the traverse guide of the winder, and wound around a perforated cylindrical body until the outer diameter became 60 mm, thereby producing a cylindrical filter cartridge. Both end faces have a surface temperature of 175 ° C
The plate was heated and welded for 5 seconds with a hot plate to obtain a filter cartridge as shown in FIG. The obtained filter cartridge was an excellent one with no foaming and no drop of the filter medium and a small pressure loss.

Examples 2 to 6 Using the same band-shaped nonwoven fabric and perforated cylindrical body as in Example 1, the number of winds (W) was 3.2778 (Example 2), respectively.
Except that 3.2917 (Example 3), 3.3847 (Example 4), 3.4118 (Example 5), and 3.1885 (Example 6) were used, the filter cartridge was all the same as in Example 1 under the same conditions. I got The denominator (M ₂ ) when the denominator was the closest approximation to the double value (2W) of these wind numbers with a fraction having two digits or less was 9, 12, 13, 17, 17, and 61, respectively. These filter cartridges have become a small initial trapping particle size as M ₂ increases. Therefore, the value of M ₂ is correlated with the initial collection particle size. Note that the initial trapping particle size does not decrease monotonously with respect to the denominator (M ₃ ) when the denominator is the closest approximation of 2W with a fraction of three digits or less. In spite of the fact that M ₃ is larger than that of Example 6, the initial trapped particle size is smaller in Example 6. Therefore, it is understood that there is no correlation with the filtration accuracy by using the M ₃ instead of M ₂ in the formula (3). In Example 5, the wind number W was smaller than that in Example 6. However, since the initial collection particle size was smaller in Example 6, the initial collection particle size was smaller than the wind number W. It turns out that it has not become monotonic increase. The filter of Example 6 had a relatively high pressure loss, and was slightly inferior in liquid permeability as compared with other filters.

Examples 7 and 8 The width of the band-shaped nonwoven fabric was 2 cm (Example 7) or 3 cm.
A filter cartridge was obtained under the same conditions as in Example 4 except for (Example 8). This filter cartridge had a larger initial collection particle size than the filter cartridge of Example 4.

Example 9 The band-shaped nonwoven fabric had an average fiber diameter of 2 μm and a basis weight of 22 g / m 2.
^{2. A} filter cartridge was obtained under the same conditions as in Example 4 except that a melt-blown nonwoven fabric having a width of 5 cm was used. This filter cartridge had a smaller initial collection particle size than the filter cartridge of Example 4.

Example 10 As a band-like nonwoven fabric, an eyelet obtained by a spunbond method was used.
With 5g / m^Two, 2dtex fine polypropylene fiber
Weave nonwoven fabric, average fiber diameter 2 μm, basis weight 22 g / m ^Two, Width 5
cm melt-blown nonwoven fabric, obtained by the spunbond method
5g / m^Two, 2dtex fine polypropylene
Three types of non-woven fabrics made of long fiber non-woven fabric with hot emboss roll
Except for using the laminated nonwoven fabric obtained by thermocompression bonding,
A filter cartridge was obtained under the same conditions as in Example 4.
Was. This filter cartridge is the filter of Example 4.
-Initial collection particle size is smaller than cartridge
there were.

Comparative Example 1 Fineness: 2 dtex, cut length: 51 using ordinary melt spinning
A polypropylene short fiber having a diameter of 14 mm and a crimp number of 14 was produced and spun to obtain a spun yarn. The spun yarn was wound around a perforated cylindrical body similar to that of Example 1 with a wind number (W) of 3.2252 to produce a filter cartridge. The both end faces were heated with a hot plate having a surface temperature of 175 ° C. for 5 seconds to weld the both end faces to obtain a filter cartridge. This filter cartridge had many irregularities on the end face and was inferior in sealing property on the end face. In addition, the initial trapped particle size was located in the middle of the initial trapped particle sizes of Example 4 and Example 5.
The pressure loss was greater than in either Example 4 or Example 5 and was poor in liquid permeability. In addition, the filtrate contained fibers of the filter medium which had foamed or dropped off, which was not preferable as a filter cartridge.

Comparative Example 2 A filter cartridge was obtained in the same manner as in Example 1 except that the number of winds (W) was changed to 0.6538. In this filter cartridge, the wound belt-like nonwoven fabric was easily detached, and was unsuitable as a filter cartridge.

Comparative Example 3 A filter cartridge was obtained in the same manner as in Example 1, except that the number of winds (W) was changed to 10.923. In this filter cartridge, the wound belt-like nonwoven fabric was easily detached, and was unsuitable as a filter cartridge.

Comparative Example 4 A splittable short fiber made of high-density polyethylene and polypropylene having a fineness of 2 dtex and a fiber length of 64 mm, which was designed such that the fiber cross section was split into eight pieces, was used as the constituent fiber of the band-shaped nonwoven fabric. The splittable short fibers were processed by a card machine into a web, and the web was processed by a hot embossing roll to obtain a nonwoven fabric. The nonwoven fabric is treated twice with a water jet device to split the splittable fiber, and the basis weight is 22 g /
A split fiber nonwoven fabric having m ² and a thickness of 210 μm was obtained. The nonwoven fabric was slit into a width of 50 mm to obtain a belt-shaped nonwoven fabric. The number of winds (W) of the winder was set to 3.1875. (In this case, M ₂ in the formula (3) becomes 8.) Then, the band-shaped nonwoven fabric is converged through the hole of the traverse guide of the winder, wound around the perforated cylindrical body until the outer diameter becomes 60 mm, and the cylindrical filter is formed. A cartridge was manufactured. Both end faces were heated with a hot plate having a surface temperature of 175 ° C. for 5 seconds to weld both end faces to obtain a filter cartridge.
The obtained filter cartridge had a slightly smaller filtration accuracy than that of Example 1, but slightly foamed and dropped the filter medium in the filtrate, and had a large pressure loss. Also, the filter cartridge is easily deformed,
It was determined that caution was required for use when the pressure loss was high.

[0076]

[Table 1]

[0077]

As is apparent from Table 1, the filter cartridge of the present invention has better liquid permeability than the conventional thread-wound filter cartridge, and has a high level of bubbling and the like seen in the conventional thread-wound filter. It has an excellent feature that the filter medium does not fall off.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an overview of a filter cartridge of the present invention.

FIG. 2 is an explanatory view showing a state in which a belt-shaped nonwoven fabric is wound by traversing.

FIG. 3 is a conceptual diagram of a spunbond nonwoven fabric.

FIG. 4 is a conceptual diagram of a short fiber nonwoven fabric.

FIG. 5 is an explanatory diagram showing a foreign matter collection state by an emboss pattern of a long-fiber nonwoven fabric.

[Description of Signs] 1 Filter cartridge 2 Perforated cylindrical body 3 Converged band-shaped nonwoven fabric 4 Band-shaped nonwoven fabric 5 Bobbin 6 Traverse guide 7 Particle 8 Long fiber constituting spunbond nonwoven fabric 9 Short fiber constituting short fiber nonwoven fabric 10 Emboss pattern Part with strong thermocompression bonding due to 11 11 Part with only weak thermocompression due to departure from embossed pattern 12 Foreign matter 13 Foreign matter passing through part with only weak thermocompression due to departure from embossed pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D019 AA03 BA13 BB03 CA03 DA02 4L047 AA14 AB03 BA08 CA05 CA19 CC12

Claims (9)

[Claims] 1. A filter cartridge formed by winding a belt-shaped nonwoven fabric made of thermoplastic fiber around a perforated tubular body in a twill shape. The number of times of winding (W) from one end to the other end in the direction is 1 to 10 per 250 mm length of the perforated tubular body.
Times the filter cartridge 2. A value (2) that is twice the number of windings (W)
2. The filter cartridge according to claim 1, wherein when W) is represented by the closest fraction that has no more than two digits in the denominator and is not reduced, the denominator of the fraction is 4 to 40. 3. 3. The width of the band-shaped nonwoven fabric is 0.5 cm to 40 cm.
The filter cartridge according to claim 1 or 2, wherein 4. The width (cm) and the basis weight (g / m) of the band-shaped nonwoven fabric.
The filter cartridge according to any one of claims 1 to 3, wherein a product of the filter cartridge and ( ² ) is 20 to 200. 5. A long-fiber nonwoven fabric in which at least a part of fiber intersections is thermally bonded.
The filter cartridge according to any one of the above. 6. The filter cartridge according to claim 5, wherein the long-fiber nonwoven fabric is a long-fiber nonwoven fabric made by a spunbond method. 7. The filter cartridge according to claim 1, wherein the band-shaped nonwoven fabric is a melt-blown nonwoven fabric. 8. The nonwoven fabric according to claim 1, wherein the belt-shaped nonwoven fabric is a nonwoven fabric obtained by laminating at least two layers of a long-fiber nonwoven fabric having at least a part of the fiber intersection points thermally bonded thereto and a melt-blown nonwoven fabric. Filter cartridge described 9. The filter cartridge according to claim 1, wherein the porosity of the filter medium of the filter cartridge is 65 to 85%.