JPH10211408A - Cylindrical filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cylindrical filter capable of being manufactured simply while its service life is long by a method wherein rough nonwoven fabric of a specific thickness wherein a relation between average fiber diameter and the most pore diameter is specified, is wound around a porous cylinder. SOLUTION: A cylindrical filter for filtering solid in liquid is constituted by winding rough nonwoven fabric wherein a relation of D>=P is effected between average fiber diameter D (μm) and most pore diameter P (μm) around a porous cylinder. Partial solid in treating fluid penetrating a rough nonwoven fabric region is caught on a surface and at an inside of an opening part of the rough nonwoven fabric thereby. The solid collides against rough nonwoven fabric constituting fiber to be diffused on the whole of the rough nonwoven fabric layer, which is enabled to be filtered. Clogging is made less prone to be generated, and its service life is prolonged. In this case, a thickness of the rough nonwoven fabric is 0.5 to 1.5mm, its volume is reduced with a load when the rough nonwoven fabric is wound around the porous cylinder, a compressional structure can be formed in the rough nonwoven fabric, and through a particle size distribution range of the solid is wide, the solid is enabled to be filtered stepwise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical filter capable of filtering solids in a fluid, and more particularly to a cylindrical filter capable of filtering solids in a liquid.

[0002]

2. Description of the Related Art Conventionally, as a filter capable of filtering solids in a liquid, a filter formed by winding a nonwoven fabric made of fine fibers formed by a melt blow method, a jet spinning method, or the like around a perforated cylinder and forming the same is known. I was This filter was prone to clogging and had a short service life.

On the other hand, there has been known a tubular filter in which a nonwoven fabric having a high apparent density is sequentially wound around a perforated cylinder from the upstream side to the downstream side of the processing liquid so as to prevent clogging. . Although this cylindrical filter has a long service life to a certain extent, it has a short service life in spite of the labor involved in manufacturing. Therefore, a cylindrical filter which has a longer service life and can be manufactured more easily has been long-awaited.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a cylindrical filter which has a long service life and can be easily manufactured.

[0005]

The tubular filter of the present invention has at least an average fiber diameter D (μm) and a most porous diameter P
(Μm), a relationship of D ≧ P is established, and a thickness of 0.
The coarse nonwoven fabric of 5 to 1.5 mm is wound around the perforated cylinder.

[0006] As described above, the cylindrical filter of the present invention has a diameter D between the average fiber diameter D (μm) and the most porous diameter P (μm).
Since the coarse nonwoven fabric satisfying the relationship of ≧ P is wound around the porous tube, some solid matter in the processing fluid that has invaded the coarse nonwoven fabric region is captured on the surface and inside the opening portion of the coarse nonwoven fabric. It is considered that some solid matter collides with the coarse nonwoven fabric constituent fibers and is diffused throughout the coarse nonwoven fabric layer, and the solid matter can be filtered through the whole coarse nonwoven fabric layer. .

The thickness of the coarse nonwoven fabric is 0.5 to 1.5 m.
m, the bulk nonwoven fabric can be easily reduced in bulk by the load when winding the coarse nonwoven fabric around the perforated cylinder, and the coarse nonwoven fabric can be formed in the coarse nonwoven fabric. However, it is considered that filtration can be performed stepwise.

Further, the tubular filter of the present invention can be formed simply by winding at least the coarse nonwoven fabric around the perforated tube, and thus can be easily manufactured.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The coarse nonwoven fabric of the present invention not only filters solid substances but also functions to promote the diffusion of solid substances in a processing fluid so as to prevent clogging. Therefore, the relationship of D ≧ P needs to be established between the average fiber diameter D (μm) and the most porous diameter P (μm) of the coarse nonwoven fabric, and the relationship of D ≧ P + 5 is more preferably established. Although the upper limit is not particularly limited, P + 2
Preferably, 0 ≧ D.

The average fiber diameter in the present invention means an average value of fiber diameters measured at arbitrary 100 points of constituent fibers of a nonwoven fabric (including nonwoven fabrics other than a coarse nonwoven fabric).
If the constituent fibers of the nonwoven fabric (including nonwoven fabrics other than the coarse nonwoven fabric) have an irregular cross-sectional shape, the diameter of a circle having the same area as the cross-sectional area is regarded as the fiber diameter. Also,
The most porous diameter is a pore size distribution measuring instrument (COULTER, CO
ULTER POROMETER) is used to measure the pore size, and as a result, refers to the pore size value having the largest pore size distribution.

The average fiber diameter of the coarse nonwoven fabric of the present invention is as follows:
Depending on the intended use of the cylindrical filter, 30-50
It is preferably μm. Therefore, the most porous diameter of the coarse nonwoven fabric is preferably 50 μm or less.

The coarse nonwoven fabric of the present invention is easily reduced in volume by a load when wound around a perforated cylinder, has a denser structure on the perforated cylinder side, and has a denser structure in the coarse nonwoven fabric.
The thickness is preferably 0.5 to 1.5 mm. Thickness 0.
If the thickness is less than 5 mm, a dense structure is unlikely to occur, while if the thickness exceeds 1.5 mm, the number of coarse nonwoven fabric layers decreases,
The service life is shortened, and the workability (workability)
The thickness is more preferably 0.6 to 1.2 mm.

The coarse nonwoven fabric of the present invention has an areal density of 50 to 50%.
It is preferably 120 g / m ² . Area density 50g /
When it is smaller than m ^2, it is difficult to form a coarse nonwoven fabric having a thickness of 0.5 mm or more, and the winding length around the porous cylinder becomes long, so that workability (workability) deteriorates.
If it exceeds 0 g / m ² , the thickness tends to exceed 1.5 mm, more preferably 60 to 100 g / m ² .

Such a coarse nonwoven fabric is formed by, for example, entanglement of a fiber web formed by a dry method such as a card method, an air lay method, a spun bond method or a melt blow method, such as a hydroentanglement method or a needle punch method. It can be formed by a method of partially or completely fusing the fibers constituting the fibrous web, a method of partially or completely bonding with an adhesive, or an appropriate combination of these methods. In addition,
When the fiber web is formed by the spun bond method or the melt blow method, the treatment for bonding the fibers can be omitted. Among these, the coarse nonwoven fabric formed by the melt blow method, the spun bond method, or the hydroentanglement method, since the fibers are not firmly fixed, the bulk is easily reduced by the load when wound around the porous cylinder, Since it is easy to form a dense structure, it can be suitably used.

The fibers constituting the coarse nonwoven fabric include, for example, recycled fibers such as rayon fibers, semi-synthetic fibers such as acetate fibers, nylon fibers, vinylon fibers, vinylidene fibers, polyvinyl chloride fibers, polyester fibers, acrylic fibers, and the like. Polyolefin fibers such as polyethylene fibers and polypropylene fibers, synthetic fibers such as polyurethane fibers, vegetable fibers such as cotton and hemp, and animal fibers such as wool can be used. Further, the fiber does not need to be composed of one type of resin component, and may be composed of two or more types of resin components. Among them, polyolefin fibers (particularly, polypropylene fibers) are excellent in chemical resistance and excellent in versatility, and thus can be suitably used.

The cylindrical filter of the present invention may be one in which only the above-mentioned coarse non-woven fabric is wound around a perforated tube, or in order to further improve the filtration performance of solids, the above-mentioned coarse filter may be used. A dense nonwoven fabric having an average fiber diameter and / or a maximum porous diameter smaller than that of the nonwoven fabric may be wound around the perforated cylinder, but the latter is more preferable.

In the case of the cylindrical filter containing the dense nonwoven fabric and the coarse nonwoven fabric, the average fiber diameter of the dense nonwoven fabric and the coarse nonwoven fabric and / or the density of the dense nonwoven fabric and the coarse nonwoven fabric at the portion where the dense nonwoven fabric and the coarse nonwoven fabric are closest to the treatment fluid outlet side Or if the difference from the most porous diameter is large,
Due to the large difference in filtration efficiency between dense nonwoven fabric and coarse nonwoven fabric,
The load on the dense nonwoven fabric increases, and clogging is likely to occur.
Since the service life is shortened, the difference between the dense nonwoven fabric and the coarse nonwoven fabric is preferably within 30 μm in the average fiber diameter and within 5 μm in the most porous diameter. As aforementioned,
Since the average fiber diameter of the coarse nonwoven fabric is preferably 30 to 50 μm, the average fiber diameter of the dense nonwoven fabric is preferably 5 to 50 μm. Further, since the most porous diameter of the coarse nonwoven fabric is preferably 50 μm or less, the most porous diameter of the dense nonwoven fabric is 50 μm or less.
It is preferably not more than μm.

When an intermediate nonwoven fabric as described below is present between the dense nonwoven fabric and the coarse nonwoven fabric, the intermediate nonwoven fabric and the coarse nonwoven fabric are located closest to the treatment fluid inflow side where the intermediate nonwoven fabric and the coarse nonwoven fabric exist. The difference between the average fiber diameter and / or the most porous diameter of the coarse nonwoven fabric is preferably substantially the same as the difference between the dense nonwoven fabric and the coarse nonwoven fabric described above. The difference from the dense nonwoven fabric is preferably within 25 μm in the average fiber diameter and within 5 μm in the most porous diameter.

The dense nonwoven fabric of the present invention also has a thickness of 0.5 so that the bulk is reduced by the load at the time of winding the porous nonwoven fabric, and the denser the nonwoven fabric, the denser the structure. It is preferably 1.5 mm. If the thickness is less than 0.5 mm, a dense structure is unlikely to be formed. On the other hand, if the thickness is more than 1.5 mm, clogging is apt to occur, shortening the service life, and poor workability (workability).
More preferably, the thickness is 0.6-1.2 mm.

Further, the areal density of the dense nonwoven fabric of the present invention is 60 to 100 g / g so as to satisfy the above-mentioned thickness.
m ² , more preferably 70 to 90 g / m ² .

Such a dense nonwoven fabric can be formed by the same method as that of the coarse nonwoven fabric or by the jet spinning method. However, it is easy to form the nonwoven fabric having the average fiber diameter and / or the most porous diameter as described above. It is preferably formed by a method. Also, as the fibers constituting the dense nonwoven fabric, the same fibers as the coarse nonwoven fabric can be used. For the same reason, polyolefin fibers (particularly, polypropylene fibers) are used.
Can be suitably used.

In the cylindrical filter of the present invention, the above-described dense nonwoven fabric and coarse nonwoven fabric are wound around the perforated tube so that the coarse nonwoven fabric exists between the dense nonwoven fabric and the dense nonwoven fabric. Is preferred. By being wound in this manner, the solid material can be filtered and diffused by the coarse nonwoven fabric, and the solid material diffused by the coarse nonwoven fabric layer can be filtered by the dense nonwoven fabric. It is considered to be.

The area where the coarse nonwoven fabric exists between the dense nonwoven fabric and the dense nonwoven fabric has a high filtration accuracy, is less likely to be clogged, and has a longer nonwoven fabric winding thickness from the processing fluid outlet side so as to prolong the service life. The thickness is preferably in the range of three-quarters of the thickness of the nonwoven fabric, and more preferably in the range of two-thirds of the thickness of the nonwoven fabric wound from the processing fluid outlet side.

When the dense nonwoven fabric and the coarse nonwoven fabric are wound around the porous tube, the coarse nonwoven fabric exists between the coarse nonwoven fabric and the coarse nonwoven fabric in order to maximize the diffusion of solids by the coarse nonwoven fabric. It is preferable to have a region, that is, a region in which only the coarse nonwoven fabric is wound. The region of only the coarse nonwoven fabric is preferably within a range of three quarters of the nonwoven fabric winding thickness from the processing fluid inflow side, and is preferably 3/4 of the nonwoven fabric winding thickness from the processing fluid inflow side.
More preferably, it is within the range of 2/20.

In addition to the above-mentioned coarse nonwoven fabric and dense nonwoven fabric,
Nonwoven fabrics with intermediate properties of these nonwoven fabrics,
When one or more intermediate nonwoven fabrics having an average fiber diameter and / or the most porous diameter larger than that of the dense nonwoven fabric and having a smaller average fiber diameter and / or the most porous diameter than the coarse nonwoven fabric are wound around the porous tube, a solid material is formed by the intermediate nonwoven fabric. Can be filtered and diffused more stepwise, so that the filtration accuracy is excellent, clogging is less likely to occur, and the service life is longer. In addition,
This intermediate nonwoven fabric may be placed anywhere, but only the region where the coarse nonwoven fabric exists between the dense nonwoven fabric and the coarse nonwoven fabric so that the filtration and diffusion of solids can be performed more effectively. Is preferably arranged in a region between the regions where is present.

The average fiber diameter and the most porous diameter of the intermediate nonwoven fabric are preferably 5 to 50 μm, and the most porous diameter is 5 to 50 μm from the relationship between the dense nonwoven fabric and the coarse nonwoven fabric.
It is preferably 0 μm or less. Also, the intermediate nonwoven fabric is preferably 0.5 to 1.5 mm in thickness, and preferably 0.6 to 1.2 mm, so that a dense structure can be formed by the load when wound around the porous tube. More preferred. Furthermore, it is preferred areal density is 60 to 100 / m ^2, and more preferably 70~90g / m ^2.

[0027] Such an intermediate nonwoven fabric can be formed by the same method as the dense nonwoven fabric, but is preferably formed by a melt blow method, a jet spinning method, a spun bond method, or a hydroentanglement method. In addition, as the fibers constituting the intermediate nonwoven fabric, polyolefin fibers (particularly, polypropylene fibers) can be suitably used.

Further, in the cylindrical filter of the present invention,
In addition to the above-mentioned coarse nonwoven fabric, dense nonwoven fabric, and intermediate nonwoven fabric, it is possible to have an extremely coarse nonwoven fabric having an average fiber diameter and / or a most porous diameter larger than that of the coarse nonwoven fabric. By having such an extremely coarse nonwoven fabric, the effect of diffusing solids can be increased, and the filtration life can be prolonged. The extremely coarse nonwoven fabric may be placed anywhere, but it is preferable that the extremely coarse nonwoven fabric be located closer to the treatment fluid inflow side than the coarse nonwoven fabric so that diffusion occurs more effectively.

The average fiber diameter and the most porous diameter of the extremely coarse nonwoven fabric are 30 μm, based on the relationship with the coarse nonwoven fabric described above.
m or more. Further, the thickness of the extremely coarse nonwoven fabric is preferably 0.1 to 1 mm, and 0.2 to 0.1 mm.
More preferably, it is 8 mm. Furthermore, the areal density is 10
It is preferably 100 g / m ² and 15 to 80 g / m ^2.
Is more preferable.

Such an extremely coarse nonwoven fabric can be formed by the same method as the coarse nonwoven fabric, but is preferably formed by a melt blow method, a jet spinning method, a spun bond method, or a hydroentanglement method. Further, as the fibers constituting the extremely coarse nonwoven fabric, polyolefin fibers (particularly, polypropylene fibers) can be suitably used.

When at least the coarse nonwoven fabric is wound around the perforated tube, the coarse nonwoven fabric is generally wound around the perforated tube under a constant load. The closer to the perforated cylinder, the more likely it is to form a dense and coarse nonwoven fabric, so the perforated cylinder side is preferably the processing fluid outflow side. Therefore, when the dense nonwoven fabric is also wound, it is preferable that the dense nonwoven fabric is in contact with the porous tube. Further, as the outermost layer, a woven fabric, a knitted fabric, a net, or the like having a coarse nonwoven fabric, an extremely coarse nonwoven fabric, or an average fiber diameter and / or a most porous diameter equal to or greater than that of the extremely coarse nonwoven fabric can be arranged.

The method for manufacturing such a tubular filter of the present invention can be manufactured as follows.

For example, in the case of a cylindrical filter in which a coarse nonwoven fabric, a dense nonwoven fabric, and an intermediate nonwoven fabric are wound around a porous tube, first,
Prepare a coarse nonwoven fabric, a dense nonwoven fabric, an intermediate nonwoven fabric, and a porous tube made of metal or plastic. Next, after cutting each nonwoven fabric to a required length, the nonwoven fabric is laminated so that one end of each nonwoven fabric coincides, or the dense nonwoven fabric and the intermediate nonwoven fabric are laminated in parallel in the length direction of the coarse nonwoven fabric on the coarse nonwoven fabric. . And the cylindrical filter of this invention can be formed by winding this laminated nonwoven fabric around the perforated cylinder. in this way,
The tubular filter of the present invention can be easily manufactured.

If the length of the dense nonwoven fabric is made shorter than the length of the coarse nonwoven fabric and the ends of the dense nonwoven fabric and the coarse nonwoven fabric are wound around a porous tube, the coarse nonwoven fabric is placed between the dense nonwoven fabric and the dense nonwoven fabric. The existing region exists within a range of three quarters of the nonwoven fabric winding thickness from the processing fluid outflow side, and the region where only the coarse nonwoven fabric is wound is defined as the nonwoven fabric winding thickness of 4/4 from the processing fluid inflow side. It is possible to form a cylindrical filter existing in a range of 3/3.

If the dense nonwoven fabric is wound so as to be in contact with the perforated tube, the perforated tube side can be used as a cylindrical filter on the processing fluid outflow side, and the nonwoven fabric other than the dense nonwoven fabric can be wound so as to be in contact with the perforated tube. If this is the case, the porous filter can form a cylindrical filter on the processing fluid inflow side.

Further, the load at the time of winding the laminated nonwoven fabric around the porous tube may be constant, or may be varied continuously or discontinuously from the beginning to the end of winding. A cylindrical filter with stable quality can be formed. When this load is constant, a larger force is applied at the beginning of winding, and each nonwoven fabric is easily deformed, and each nonwoven fabric is more likely to form a dense structure. It can be easily formed.

As described above, the cylindrical filter of the present invention can be efficiently filtered even if the particle size distribution of solids is wide, and is excellent in terms of service life. , Water treatment, photography, paint, plating, dyeing, machinery
It can be used in various manufacturing processes such as steel, or used for filtering a fluid such as a used liquid.

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

[0039]

【Example】

(Example 1) An average fiber diameter of 35 μm, a most porous diameter of 30 μm made of polypropylene fibers by a spunbond method,
A coarse nonwoven fabric having an area density of 100 g / m ² and a thickness of 1 mm was formed. On the other hand, a dense nonwoven fabric made of polypropylene fibers and having an average fiber diameter of 6 μm, a maximum porous diameter of 25 μm, an area density of 80 g / m ² , and a thickness of 1 mm was formed by a melt blow method.

Next, the coarse nonwoven fabric was cut into a length of 320 cm, and the dense nonwoven fabric was cut into a length of 40 cm. Then, one end of the coarse nonwoven fabric and one end of the dense nonwoven fabric were overlapped with each other. A constant load (0.15 cm) around a thickness of 0.15 cm (the same applies to the following examples).
At 39 MPa), the dense nonwoven fabric is wound so as to be in contact with the porous tube, and has an inner diameter of 2.8 cm, an outer diameter of 6.5 cm, and a length of 25 cm.
cm cylindrical filter was produced. The dense nonwoven fabric was present in a range from the porous cylinder side (processing fluid outflow side) to 0.6 cm (about one third of the nonwoven fabric winding thickness).

Example 2 An average fiber diameter of 40 μm, a maximum porous diameter of 32 μm, and a surface density of 60 g / polypropylene fiber formed by a hydroentanglement method as a coarse nonwoven fabric.
m ² , except that a 0.7 mm thick nonwoven fabric was used,
In the same manner as in Example 1, a 320 cm long non-woven fabric and a 40 cm long dense non-woven fabric were wound around a perforated cylinder to form a cylindrical filter having an inner diameter of 2.8 cm, an outer diameter of 6.5 cm, and a length of 25 cm. Produced. Note that the dense nonwoven fabric was present in a range from the porous cylinder side (processing fluid outflow side) to 0.5 cm (three-tenths of the nonwoven fabric winding thickness).

Example 3 A coarse nonwoven fabric made of polypropylene fibers and having an average fiber diameter of 35 μm, a maximum porous diameter of 30 μm, an area density of 100 g / m ² , and a thickness of 1 mm was formed by a spun bond method. An extremely coarse nonwoven fabric made of polypropylene fibers having an average fiber diameter of 37 μm, a maximum porous diameter of 50 μm, a surface density of 15 g / m ² , and a thickness of 0.2 mm was formed by a spun bond method. On the other hand, a dense nonwoven fabric made of polypropylene fibers and having an average fiber diameter of 6 μm, a maximum porous diameter of 25 μm, an area density of 80 g / m ² , and a thickness of 1 mm was formed by a melt blow method.

Next, the coarse nonwoven fabric and the extremely coarse nonwoven fabric were
After cutting the non-woven fabric into 40 cm length,
One end of the extremely coarse nonwoven fabric, one end of the coarse nonwoven fabric, and one end of the dense nonwoven fabric are sequentially superimposed so as to coincide with each other. Then, a constant load (0.39MP) is applied around the perforated polypropylene cylinder.
In (a), the dense nonwoven fabric was wound so as to be in contact with the porous tube, thereby producing a cylindrical filter having an inner diameter of 2.8 cm, an outer diameter of 6.5 cm, and a length of 25 cm. The dense nonwoven fabric was present in a range from the porous cylinder side (processing fluid outflow side) to 0.6 cm (about one third of the nonwoven fabric winding thickness).

Example 4 The following five types of nonwoven fabrics were formed. Coarse nonwoven fabric; average fiber diameter 3 consisting of polypropylene fiber
5 μm, 30 μm maximum porous diameter, 100 g / m ^{2 area} density, 1 mm thick spunbond nonwoven dense nonwoven cloth; average fiber diameter of 2.3 μm made of polypropylene fiber, 10 μm maximum porous diameter, 80 g / m ^{2 area} density,
Melt blown non-woven fabric having a thickness of 0.9 mm, intermediate non-woven fabric A; made of polypropylene fiber, melt-blown non-woven fabric having an average fiber diameter of 6 μm, a maximum porous diameter of 25 μm, an areal density of 80 g / m ² , and a thickness of 1.0 mm. Average fiber diameter 3.5μm, maximum porosity 18μm, area density 80g /
m ² , melt-blown non-woven fabric having a thickness of 1.2 mm Intermediate non-woven fabric C; polypropylene fiber, average fiber diameter 3.1 μm, maximum porosity 15 μm, area density 80 g /
Melt blown non-woven fabric with m ² and thickness of 1.3mm

Next, the coarse nonwoven fabric is cut into a length of 320 cm, and the intermediate nonwoven fabrics A, B, and C and the dense nonwoven fabric are cut into a length of 40 cm. Then, the left end of the coarse nonwoven fabric and the left end of the dense nonwoven fabric coincide with each other on the coarse nonwoven fabric. Further, the coarse non-woven fabric is aligned so that the right end of the dense non-woven fabric and the left end of the intermediate non-woven fabric C, the right end of the intermediate non-woven fabric C and the left end of the intermediate non-woven fabric B, and the right end of the intermediate non-woven fabric B and the left end of the intermediate non-woven fabric A coincide. Laminated on top.

Then, the dense nonwoven fabric was wound around the perforated polypropylene cylinder at a constant load (0.39 MPa) so as to come into contact with the perforated cylinder, and had an inner diameter of 2.8 cm, an outer diameter of 6.5 cm and a length of 25 cm. A cylindrical filter was manufactured.
In addition, the dense nonwoven fabric is from the porous cylinder side (the processing fluid outflow side)
It was present in the range up to 0.6 cm (about one third of the nonwoven roll thickness).

(Comparative Example 1) The following six types of nonwoven fabrics were produced. Non-woven fabric A; made of polypropylene fiber, average fiber diameter 6
[mu] m, most porous diameter 25 [mu] m, surface density 80 g / m ^2, a thickness of 1.0 mm, melt-blown nonwoven nonwoven B of length 40 cm; made of polypropylene fibers, the average fiber diameter of 7.6 [mu] m, most porous diameter 29 .mu.m, the surface density 80 g / m ² ,
Melt blown nonwoven fabric having a thickness of 1.0 mm and a length of 40 cm Nonwoven fabric C; made of polypropylene fiber, average fiber diameter: 9.1 μm, maximum porous diameter: 36 μm, surface density: 80 g / m ² ,
Melt blown nonwoven fabric 1.1 mm thick and 40 cm long Nonwoven fabric D; average fiber diameter 1 consisting of polypropylene fiber
1.6 μm, maximum porous diameter 41 μm, area density 80 g / m ² ,
Melt blown non-woven fabric 0.9 mm thick and 40 cm long Non-woven fabric E;
4.0 μm, maximum porous diameter 46 μm, area density 80 g / m ² ,
Melt blown non-woven fabric having a thickness of 1.2 mm and a length of 40 cm Non-woven fabric F;
7 μm, 50 μm maximum porous diameter, 15 g / m ² areal density, 0.2 mm thick, 750 cm long spunbond nonwoven fabric

Next, the non-woven fabric F is laminated on the non-woven fabric F so that the left end thereof coincides with the left end of the non-woven fabric A. Further, the right end of the non-woven fabric A and the left end of the non-woven fabric B, the right end of the non-woven fabric B and the left end of the non-woven fabric C, The right end of the nonwoven fabric C and the left end of the nonwoven fabric D, the nonwoven fabric D
Were laminated on the non-woven fabric F such that the right end of the non-woven fabric E and the left end of the non-woven fabric E coincided with each other. Next, the nonwoven fabric A is wound around the perforated polypropylene cylinder at a constant load (0.39 MPa) so that the nonwoven fabric A comes into contact with the perforated cylinder, and a cylindrical filter having an inner diameter of 2.8 cm, an outer diameter of 6.5 cm, and a length of 25 cm. Was prepared.

Comparative Example 2 Example 1 was repeated except that a coarse nonwoven fabric made of polypropylene fibers and having an average fiber diameter of 35 μm, a maximum porous diameter of 30 μm, an area density of 200 g / m ² , and a thickness of 2 mm was used. In the same manner as described above, and laminated with a dense nonwoven fabric, wound around a perforated cylinder, and has an inner diameter of 2.8c.
m, a cylindrical filter having an outer diameter of 6.5 cm and a length of 25 cm was prepared. The dense non-woven fabric is on the perforated cylinder side (processing fluid outflow side)
To 1.1 cm (about two-thirds of the nonwoven fabric roll thickness).

Comparative Example 3 A cylindrical filter (made by Chisso Corporation, nominal accuracy: 3 μm, CP-03) was prepared by molding a heat-bonding fiber made of a polyolefin fiber into a cylindrical shape.

(Comparative Example 4)
A cylindrical filter (made by Chisso Corporation, nominal accuracy 3 μm, BM-ASGO, made of ultrafine polypropylene composite fiber comprising a high melting point component and a low melting point component, having a density gradient,
Japanese Patent Publication No. 7-98131).

(Water resistance) Examples 1 to 4 and Comparative Examples 1 to
The initial pressure loss when water was passed through each of the cylindrical filters of No. 4 at a flow rate of 25 L / min was measured and defined as a water flow resistance. The results were as shown in Table 1.

[0053]

[Table 1]

(Filtration Accuracy) While uniformly stirring a test solution having a concentration of 10 ppm in which JIS type 8 dust is dispersed in water, a flow rate of 25 L / The filtrate was collected one minute after the start of water supply, and the number of particles contained in the filtrate after one minute and the test liquid before filtration was measured using a particle size distribution analyzer (COULTER Multisizer II, manufactured by COULTER). Was measured for each particle size. Next, the collection efficiency at each particle size was determined by the following equation, and the particle size at which a collection efficiency of 100% was obtained was defined as the filtration accuracy of the cartridge. The results are as shown in Table 1. Collection efficiency [%] = {(AB) / A} × 100 A: number of particles before filtration, B: number of particles after filtration

(Service life) While uniformly stirring a test solution having a concentration of 100 ppm in which JIS type 8 dust is dispersed in water,
Water was passed through each of the cylindrical filters of Examples 1 to 4 and Comparative Examples 1 to 4 at a flow rate of 25 L / min, and the pressure loss was measured for each flow rate. The total treated water flow was measured and defined as the service life. The results are as shown in Table 1.

The filters having the same water flow resistance were compared (Examples 1 to 3 and Comparative Examples 1 to 3 and Example 4 and Comparative Example 4). It can be seen that the filter has excellent filtration accuracy and has a remarkably long service life.

[0057]

The tubular filter of the present invention has at least
Between the average fiber diameter D (μm) and the most porous diameter P (μm),
A coarse nonwoven fabric having a thickness of 0.5 to 1.5 mm and satisfying a relationship of D ≧ P is wound around a perforated cylinder.

As described above, the cylindrical filter of the present invention has a D filter between the average fiber diameter D (μm) and the most porous diameter P (μm).
Since the coarse nonwoven fabric satisfying the relationship of ≧ P is wound around the porous tube, some solid matter in the processing fluid that has invaded the coarse nonwoven fabric region is captured on the surface and inside the opening portion of the coarse nonwoven fabric. It is considered that some solid matter collides with the coarse nonwoven fabric constituent fibers and is diffused throughout the coarse nonwoven fabric layer, and the solid matter can be filtered through the whole coarse nonwoven fabric layer. .

The thickness of the coarse nonwoven fabric is 0.5 to 1.5 m.
m, the bulk nonwoven fabric can be easily reduced in bulk by the load when winding the coarse nonwoven fabric around the perforated cylinder, and the coarse nonwoven fabric can be formed in the coarse nonwoven fabric. However, it is considered that filtration can be performed stepwise.

Furthermore, the tubular filter of the present invention can be formed simply by winding at least the coarse nonwoven fabric around the perforated tube, and thus can be easily manufactured.

Claims (7)

[Claims] 1. A relation of D ≧ P is established at least between an average fiber diameter D (μm) and a most porous diameter P (μm).
A cylindrical filter, wherein a coarse nonwoven fabric having a thickness of 0.5 to 1.5 mm is wound around a perforated cylinder. 2. A dense nonwoven fabric having a smaller average fiber diameter and / or a maximum porous diameter than the coarse nonwoven fabric is wound around the perforated cylinder, and a region where the coarse nonwoven fabric exists between the dense nonwoven fabric and the dense nonwoven fabric. The cylindrical filter according to claim 1, further comprising: 3. The region where the coarse nonwoven fabric exists between the dense nonwoven fabric and the dense nonwoven fabric is within a range of three quarters of the nonwoven fabric winding thickness from the treatment fluid outlet side. 2. The cylindrical filter according to 2. 4. The region according to claim 1, wherein the area of only the coarse nonwoven fabric is within a range of three quarters of the nonwoven fabric winding thickness from the treatment fluid inflow side. Cylindrical filter. 5. The average fiber diameter and / or the most porous diameter are larger than the dense nonwoven fabric, and the average fiber diameter and / or the average fiber diameter are larger than the coarse nonwoven fabric.
The cylindrical filter according to any one of claims 2 to 4, wherein one or more intermediate nonwoven fabrics having the smallest porous diameter are wound around the porous cylinder. 6. The method according to claim 1, wherein an extremely coarse nonwoven fabric having an average fiber diameter and / or a most porous diameter larger than that of the coarse nonwoven fabric is wound around the perforated cylinder. The cylindrical filter as described in the above. 7. The tubular filter according to claim 1, comprising a coarse nonwoven fabric selected from a meltblown nonwoven fabric, a spunbonded nonwoven fabric, and a hydroentangled nonwoven fabric.