JP2001300223A - Cylindrical filter - Google Patents

Abstract

(57) [Problem] To provide a tubular filter having a long filtration life and capable of being manufactured with good workability such as folding. SOLUTION: The cylindrical filter of the present invention is a main filtration nonwoven fabric made of fibers that are not substantially fibrillated and have a fiber diameter of less than 20 μm, and as the fibers, ultrafine fibers having a fiber diameter of 4 μm or less; Fiber diameter is 8μm or more, 20
a main filtration nonwoven fabric having an adhesive fiber of less than μm and having a maximum pore size of not more than twice the average flow pore size, and an auxiliary filtration fiber sheet having an average flow pore size larger than the main filtration nonwoven fabric, The main filtration nonwoven fabric and the auxiliary filtration fiber sheet are arranged adjacent to each other in a state of being laminated adjacent to each other.

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 As a filter capable of filtering solids in a liquid, a so-called pleated filter in which a pleated filter material is arranged around a perforated cylinder has been known. This pleated filter is a suitable filter because of its large filtration area and long filtration life. As a filter material constituting the pleated filter, a nonwoven fabric obtained by subjecting a melt-blown nonwoven fabric to pressure treatment with a hot calender roll is known. Since this filter medium has a fine pore diameter, a desired filtration efficiency can be obtained. However, there is a problem that clogging is apt to occur due to poor fluid permeability and the filtration life is short. In addition, since this filter medium has no strength, there is a problem that foldability is poor. In order to improve the fold-folding property, a filter material in which a net is laminated on a melt-blown nonwoven fabric is known. Although the filter material in which the net is laminated improves the fold-folding property, the melt-blown nonwoven fabric may be damaged. Further, since the net hardly contributes to filtration, it was not sufficiently satisfactory in terms of filtration life. Such a problem was sometimes found in the case of a so-called depth filter in which a filtering material was wound in a flat wound shape around a perforated cylinder.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and provides a cylindrical filter which has a long filtration life and can be manufactured with good workability such as folding. The purpose is to provide.

[0004]

According to the present invention, there is provided a cylindrical filter having a fiber diameter of 20 μm which is not substantially fibrillated.
The main non-woven fabric is manufactured from fibers having a fiber diameter of less than 4 μm and a bonded fiber having a diameter of 8 μm or more and less than 20 μm. Including a main filtration nonwoven fabric having a flow rate pore diameter of twice or less and an auxiliary filtration fiber sheet having a larger average flow pore diameter than the main filtration nonwoven cloth, the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are laminated adjacent to each other. In this state, it is arranged around the perforated cylinder. The inventors of the present invention have conducted intensive studies and as a result, the specific main filtration nonwoven fabric as described above has a long filtration life and is excellent in filtration performance. It has been found that the combination of an auxiliary filtration fiber sheet having a large flow pore diameter further increases the filtration life. In addition, it is also found that the specific main filtration nonwoven fabric as described above is excellent in the strength bonded by the adhesive fiber, so that it can be manufactured with good workability (for example, foldability, winding property). It was.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The main filtration nonwoven fabric of the present invention is manufactured from fibers which are not substantially fibrillated so that the fibers do not become entangled with each other during formation of the main filtration nonwoven fabric, thereby impairing the uniform dispersion of the fibers. Is done. The term "non-fibrillated fiber" means a fiber in which a plurality of fibers are not bonded, for example, a fiber in which a countless number of fibers are branched from one fiber (for example, a fiber beaten by a beater or the like, Pulp or the like, or a fiber in which a plurality of fibers are already bonded and in a network state (for example, a fiber obtained by a flash spinning method).

The main filtering nonwoven fabric of the present invention has a fiber diameter of 20 so that the arrangement of the fibers is disturbed due to the mixture of the thick fibers, and a large opening diameter is not formed.
It is manufactured from fibers having a diameter of less than μm (preferably fibers having a fiber diameter of 18 μm or less). The "fiber diameter" in the present invention refers to the diameter of the fiber when the cross-sectional shape of the fiber is circular, and the diameter when converted to a circular cross-section when the cross-sectional shape of the fiber is non-circular. Say. More specifically, the main filtration nonwoven fabric of the present invention contains ultrafine fibers having a fiber diameter of 4 μm or less and bonded adhesive fibers having a fiber diameter of 8 μm or more and less than 20 μm. The former ultrafine fiber has a fiber diameter of 4 μm so that it can be uniformly dispersed to form a uniform pore size.
m or less, and more preferably 3 μm or less. The lower limit of the fiber diameter of the ultrafine fiber is not particularly limited, but is preferably 0.1 μm or more,
It is more preferably 0.3 μm or more, further preferably 0.5 μm or more, and most preferably 0.75 μm or more. It is preferable that the diameters of the ultrafine fibers are substantially the same so that a uniform pore diameter can be formed by the above-described ultrafine fibers. That is, the value obtained by dividing the standard deviation value of the fiber diameter distribution of the ultrafine fibers by the average value of the fiber diameters of the ultrafine fibers is preferably 0.2 or less (preferably 0.18 or less). When the fiber diameters of the ultrafine fibers are all the same, the standard deviation is 0. Therefore, the lower limit of the value obtained by dividing the standard deviation of the fiber diameter distribution of the ultrafine fibers by the average value of the fiber diameters of the ultrafine fibers. Is 0. "Average fiber diameter" of this microfiber
Means a value obtained by taking an electron micrograph of the main filtration nonwoven fabric, measuring the fiber diameters of 100 or more (n) ultrafine fibers in the electron micrograph, and averaging the measured fiber diameters. Further, the “standard deviation value” of the ultrafine fiber refers to a value obtained by calculating the measured fiber diameter (χ) from the following equation. Standard deviation = {(nΣχ ² − (Σχ) ² ) / n (n−1)}
^1/2 where n means the number of the measured ultrafine fibers, and χ means the fiber diameter of each ultrafine fiber. The fiber diameter is 4
When there are two or more types of ultrafine fibers having a size of not more than μm, it is preferable that the above relationship is satisfied for each of the ultrafine fibers. Further, it is preferable that the ultrafine fibers have substantially the same diameter in the fiber axis direction of the ultrafine fibers so that a main filtration nonwoven fabric having a uniform pore diameter can be formed. Such microfibers having substantially the same fiber diameter, or microfibers having substantially the same diameter in the fiber axis direction, for example, extrude the island component by spinning the sea component at the spinneret. It can be obtained by removing the sea component of the sea-island type fiber obtained by the compound spinning method such as the compounding method. In addition, by removing the sea component of the sea-island type fiber obtained by a method of spinning after mixing the resin constituting the island component and the resin constituting the sea component, which is generally called a mixed spinning method, is substantially the same. It is difficult to obtain ultrafine fibers having a fiber diameter or ultrafine fibers having substantially the same diameter in the fiber axis direction.

[0007] The resin constituting the ultrafine fibers is not particularly limited, but, for example, nylon 6, nylon 66,
Polyamide such as nylon copolymer, polyethylene terephthalate, polyethylene terephthalate copolymer, polybutylene terephthalate, polyester such as polybutylene terephthalate copolymer, polyethylene, polypropylene, poly-4-methyl-1-pentene, olefin It can be composed of one or more kinds of synthetic resins such as polyolefins such as copolymers, polystyrenes, polyurethanes and vinyl polymers. In addition, when the ultrafine fiber contains a resin component capable of participating in adhesion (hereinafter, sometimes referred to as an “adhesive component”) and is adhered by this adhesive component, the ultrafine fiber can be reliably fixed, This is a preferred embodiment because it does not fall off or fluff. When bonding the ultrafine fibers, the ultrafine fibers can be composed of only the adhesive component composed of the resin as described above, or the adhesive component and a component having a melting point higher than the melting point of the adhesive component (hereinafter referred to as “non-adhesive”). Component)).
Among these, when the ultrafine fiber is composed of two or more components including an adhesive component and a non-adhesive component as in the latter, the fiber morphology is maintained even when the adhesive component is adhered, and the original function of the ultrafine fiber is maintained. This is more preferable because it is difficult to prevent the formation of a uniform pore size. When the ultrafine fiber is composed of two or more types of components, the adhesive component occupies at least a part of the surface of the ultrafine fiber so as to be able to participate in the adhesion. , Eccentric type, side-by-side type, sea-island type, orange type, multiple bimetal type, etc.), and the entire microfine fiber surface (the cross-sectional shape of the ultrafine fiber is core-sheath type, eccentric type, sea-island type, etc.). More preferably. On the other hand, the non-adhesive component has a melting point of 10
It is preferable that the temperature is higher by at least 20 ° C., and it is more preferable that the temperature is higher by at least 20 ° C. Preferably, the non-adhesive component has a melting point higher by at least 10 ° C. than the temperature at which the adhesive fiber described below is bonded so that the fiber shape can be maintained even by the heat at the time of bonding the adhesive fiber described below. , More preferably at least 20 ° C. or higher. The microfiber composed of two or more resin components including a suitable adhesive component and a non-adhesive component,
When spinning sea-island type fibers by a conventional composite spinning method, as a die for extruding the island component, the cross-sectional shape as described above (for example, core-sheath type, eccentric type, side-by-side type, sea-island type,
It can be obtained by spinning sea-island fibers using a material capable of forming an orange type, a multi-bimetal type, etc., and removing sea components. The “melting point” in the present invention refers to a temperature at which a maximum value of a melting endothermic curve obtained by raising the temperature from room temperature using a differential scanning calorimeter at a temperature rise rate of 10 ° C./min is used. When there are two or more maximum values, the maximum value at the highest temperature is defined as the melting point. In addition, the ultrafine fiber may have properties such as crimping property and splitting property in addition to the adhesive property as described above. As the former ultrafine fiber,
A fiber in which two or more kinds of resin components are arranged can be used so that the cross-sectional shape of the ultrafine fiber is an eccentric type or a side-by-side type. Fibers in which two or more types of resin components are arranged can be used as in a bimetal type.

[0008] As described later, the ultrafine fibers are preferably short fibers (having a fiber length of 30 mm or less) having a high degree of freedom so as to be easily dispersed uniformly. If the ultrafine fibers or island components are press-bonded to each other, it will be in the same state as the fibrillated fiber, so when cutting, use ultra-fine fibers or sea-island fibers that are hard to press-bond between the ultrafine fibers or island components. Is preferred. Examples of such ultrafine fibers or sea-island fibers that are difficult to press-bond include, for example, ultrafine fibers having high crystallinity (in the case of sea-island fibers, island components). More specifically, when the ultrafine fiber (island component in the case of sea-island type fiber) contains polymethylpentene or syndiotactic polystyrene, or contains polypropylene, the melting point of the polypropylene is 166 ° C. or higher. (Preferably 168 ° C. or higher).

[0009] The other adhesive fiber must be thicker than the ultrafine fiber and have a fiber diameter of 8 µm or more so that the ultrafine fiber can be adhered to fix the ultrafine fiber and to give strength to the main filtration nonwoven fabric. Further, the fiber diameter needs to be less than 20 μm so that the arrangement of the ultrafine fibers is not disturbed by the adhesive fiber to form a large opening diameter. The more preferable fiber diameter of the adhesive fiber is 8 μm or more and 18 μm or less. The adhesive fiber may be composed of a single component, but is preferably composed of two or more resin components so that the fiber form is maintained and the strength is excellent even after bonding. The arrangement state of the two or more resin components includes, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, and a multiple bimetal type in which the fiber cross-sectional shape is. Among these, a resin capable of participating in adhesion, that is, a core-sheath type, an eccentric type, or a sea-island type having a large amount of an adhesive component is preferable. This adhesive fiber can be made of the same resin as the ultrafine fiber, but when the ultrafine fiber is not bonded, so that even the ultrafine fiber is not melted by heat at the time of bonding the adhesive fiber, The melting point of the adhesive component of the adhesive fiber is preferably lower than the melting point of any resin component of the ultrafine fiber by 10 ° C. or more, more preferably 20 ° C. or more. On the other hand, when the adhesive component of the microfiber is also bonded, the bonding of the adhesive component of the adhesive fiber and the microfiber is performed so that both the bonding of the adhesive component of the adhesive fiber and the bonding of the adhesive component of the microfiber can be performed. The melting point difference with the component is 35 ° C
Is preferably within 30 ° C, more preferably within 30 ° C. In addition, the melting point of the adhesive component of the adhesive fiber and the melting point of the adhesive component of the microfiber (when a plurality of microfibers are present, the melting point of the resin component having the closest melting point to the adhesive component of the adhesive fiber) and When the difference is not less than 10 ° C. and not more than 35 ° C., the adhesive component of the ultrafine fibers can be bonded, or the ultrafine fibers can not be bonded. When the ultrafine fiber contains an adhesive component and a non-adhesive component, the melting point of the adhesive component of the adhesive fiber is 10 ° C. lower than the melting point of the non-adhesive component of the ultrafine fiber so that the ultrafine fiber can maintain the fiber shape. Or lower, more preferably 20 ° C. or higher. Further, when the adhesive fiber is composed of two or more kinds of resin components, the resin component other than the adhesive component (non-adhesive) is so formed that the adhesive fiber can maintain the fiber shape even by the heat at the time of bonding the adhesive fiber. The melting point of the component (A) is preferably higher by 10 ° C. or more than the melting point of the adhesive component, and more preferably by 20 ° C. or more. Such an adhesive fiber can be easily spun by a conventional composite spinning method or mixed spinning method, and can be easily obtained because it is commercially available.

[0010] The main filtration nonwoven fabric of the present invention contains the above-mentioned ultrafine fibers and adhesive fibers, and the mass ratio of these fibers varies depending on the specific application and required physical properties of the cylindrical filter. (Fine fiber): (adhesive fiber) = 30 to
70: 70-30 is preferred. 3 extra fine fibers
When it is 0 mass% or more, it is easy to obtain a main filtration nonwoven fabric having a narrow pore size distribution, while the amount of adhesive fibers is 30 m.
When the content is ass% or more, the ultrafine fibers can be sufficiently fixed, so that the ultrafine fibers do not easily fall off, and the strength can be imparted to the main filtration nonwoven fabric. A more preferable mass ratio is (ultrafine fiber) :( adhesive fiber) = 35 to 6
5: 65-35. In addition, these mass ratios refer to the ratio to the entire mass of the main filtration nonwoven fabric.

[0011] The main filtered nonwoven fabric of the present invention has a fiber diameter of more than 4 µm and 8 µm in addition to the aforementioned ultrafine fibers and adhesive fibers.
Fibers (hereinafter sometimes referred to as “intermediate fiber diameter fibers”). The content of the intermediate fiber is 40 m from the relationship with the ultrafine fiber and the adhesive fiber.
It is preferably at most ass%, more preferably at most 30 mass%. That is, (ultrafine fiber) :( adhesive fiber) :( intermediate fiber diameter fiber) = 30-70: 70-
30: 0 to 40, preferably (ultrafine fiber):
(Adhesive fiber): (intermediate fiber diameter fiber) = 35 to 65: 6
The ratio is more preferably from 5 to 35: 0 to 30.

The fibers (eg, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the main filtration nonwoven fabric of the present invention can be in an undrawn state, but the main filtration nonwoven fabric is excellent in strength. Thus, it is preferable to be in a stretched state. The fiber length of the fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the main filtration nonwoven fabric of the present invention is not particularly limited. Is high and can be dispersed uniformly,
In the case where the main filtration nonwoven fabric is manufactured by a wet method in which the fibers are easily dispersed uniformly, the shorter the fiber length is, the better.
It is preferably from 5 to 30 mm. Preferably, the fibers constituting the main filtration nonwoven fabric (eg, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) have a fiber length of 0.5 to 30 mm.
Has been disconnected. The fiber length is JIS L 101
5 (Chemical fiber staple test method) A length obtained by the method B (corrected staple diagram method).

[0013] The main filtration nonwoven fabric of the present invention is composed of the above-mentioned fibers and has a narrow pore size distribution with a maximum pore size of 2 times or less (more preferably 1.9 times or less) the average flow pore size. In addition, ideally, the maximum pore diameter is 1 time of the average flow pore diameter,
That is, the total hole diameters are the same. The “average flow pore size” in the present invention refers to a value obtained by a method specified in ASTM-F316, and is, for example, a porometer (Po).
lometer, manufactured by Coulter)
Is the value measured by means of the mean flow point method, and the "maximum pore size" is a porometer (Poromete).
r, manufactured by Coulter Co., Ltd.) by the bubble point method.

When the fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the main filtration nonwoven fabric are substantially two-dimensionally arranged, the fibers are regularly arranged. Thus, the pore size distribution can be further narrowed, which is a preferable embodiment. In addition, "the fibers are substantially arranged two-dimensionally" means a state in which the fibers oriented in the thickness direction of the main filtration nonwoven fabric are not substantially arranged, for example, formed by a wet method. This is a state that can be obtained when the fiber web is bonded with the adhesive fiber without causing a fluid flow such as a water flow to act on the fiber web.

[0015] The main filtration nonwoven fabric of the present invention can be produced, for example, as follows. First, at least an ultrafine fiber and an adhesive fiber are prepared. As the ultrafine fibers, those having substantially the same fiber diameter, that is, the value obtained by dividing the standard deviation value of the fiber diameter distribution of the ultrafine fibers by the average value of the fiber diameter of the ultrafine fibers is 0.2 or less (preferably 0.18 or less) , 0 or more), it becomes easy to produce a main filtration nonwoven fabric having a narrow pore size distribution. When forming a fiber web by a wet method, fibers having a fiber length of 0.5 to 30 mm (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) are prepared. In addition, when fibers (for example, ultrafine fibers) that are not easily pressed during cutting are used, the dispersibility of the fibers is improved, and a main filtration nonwoven fabric having a narrow pore size distribution can be easily manufactured. Next, using these fibers, a fiber web is formed by a conventional wet method. Since the fibers used in the present invention are not substantially fibrillated, the fibers can be uniformly dispersed in water as a dispersing bath, and the fibers do not become entangled with the wire for making the fibers. And a desired main filtration nonwoven fabric excellent in the above. When forming this fiber web, adding a thickener to maintain a uniform dispersion state of the fiber,
Add a surfactant to increase the affinity between water and fiber (especially when using a fiber made of a resin component with low affinity for water), or add an antifoaming agent to remove air bubbles generated by stirring and the like. When added, the dispersibility of the fiber is improved, and it becomes easy to produce a main filtration nonwoven fabric having a narrow pore size distribution.

Next, simultaneously with or after drying the fibrous web, heat (and pressure, if necessary) is applied to which the adhesive component of the adhesive fiber can be attached (or the adhesive component of the ultrafine fiber can be attached in some cases). Thereby, the adhesive component of the adhesive fiber (and the adhesive component of the microfiber in some cases) can be adhered to obtain the main filtered nonwoven fabric of the present invention. As described above, when the main filtration nonwoven fabric is manufactured by bonding the adhesive component of the adhesive fiber (the adhesive component of the microfiber in some cases) without causing a fluid flow such as a water flow to act on the fiber web, the fibers are three-dimensionally arranged. Since it is not two-dimensionally arranged, it is easy to manufacture a main filtration nonwoven fabric having a narrow pore size distribution.

[0017] It should be noted that the main filtration nonwoven fabric may be subjected to a calendering treatment to increase the density or smooth the surface, or may be subjected to a physical treatment and / or a chemical treatment to impart or enhance hydrophilicity. good. In addition, the areal density of the main filtration nonwoven fabric is 5
It is preferably about 200 to 200 g / m ² , and the thickness is 0.1 g / m ² .
It is preferably about 005 to 2 mm, and the apparent density is preferably about 0.2 to 0.7 g / cm ³ . Further, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, and more preferably about 0.5 to 20 μm.

[0018] The tubular filter of the present invention comprises, in addition to the above-mentioned main filtration nonwoven fabric, an auxiliary filtration fiber sheet having an average flow pore size larger than that of the above-mentioned main filtration nonwoven fabric. Are stacked adjacent to each other,
Since the large solids can be filtered by the auxiliary filtration fiber sheet, the load on the main filtration nonwoven fabric can be reduced, so that the filtration life can be extended, and the adhesion of the main filtration nonwoven fabric can be suppressed by the auxiliary filtration fiber sheet. Thus, the filtration performance of the main filtration nonwoven fabric can be sufficiently exhibited.

[0019] Such an auxiliary filtration fiber sheet is a fiber sheet having a larger average flow pore diameter than the main filtration nonwoven fabric, but the degree thereof is not particularly limited because it varies depending on the fluid to be filtered. It is preferably about 2 to 40 μm larger than the average flow pore diameter of the nonwoven fabric.
More preferably, it is about 0 μm larger. That is, as described above, the average flow pore size of the main filtration nonwoven fabric is preferably about 0.5 to 40 μm, and more preferably about 0.5 to 20 μm.
It is preferably about 5 to 80 μm, and 2.5 to 60 μm.
m, more preferably about 2.5 to 40 μm.

[0020] As such an auxiliary filtration fiber sheet, for example, a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof can be used, and a nonwoven fabric having excellent filtration performance is preferable. , Melt-blown non-woven fabric, spun-bond non-woven fabric, non-woven fabric in which melt-blown fiber and thermoplastic stretched fiber are mixed, non-woven fabric comprising two or more resin components, and containing two or more types of ultrafine fibers generated from splittable fibers which can be split by external force It is preferred to use Since the wet nonwoven fabric has a narrow pore size distribution, the filtration accuracy of the cylindrical filter can be further improved. This `` wet nonwoven fabric '' means that after forming a fibrous web by the wet method, the fibrous web is entangled by a fluid flow such as a water flow, or the fibrous web contains thermoplastic fibers and is bonded by thermoplastic fibers. Or with an emulsion binder or latex binder,
A nonwoven fabric obtained by combining these fibers by using them in combination. Among these, a wet nonwoven fabric containing thermoplastic fibers and bonded with the thermoplastic fibers is suitable because it has appropriate rigidity and can further improve workability. Examples of the thermoplastic fiber include a polyester resin, a polyamide resin, a polyolefin resin (for example, a polyethylene resin and a polypropylene resin), a polyvinylidene chloride resin, a polyvinyl chloride resin, a polystyrene resin, and a polystyrene resin. Fibers containing one or more resins such as acrylonitrile-based resins and polyvinyl alcohol-based resins can be used. Among these thermoplastic fibers, polyolefin fibers (particularly, polypropylene fibers) are excellent in chemical resistance and versatility, and thus can be suitably used. In addition, the thermoplastic fiber does not need to be one kind, but may include two or more kinds. The content of the thermoplastic fiber is preferably as large as possible. Specifically, the content is preferably 50 mass% or more, more preferably 80 mass% or more, and most preferably 100 mass% thermoplastic fiber. preferable. Non-thermoplastic fibers (for example, regenerated fibers such as rayon fibers, semi-synthetic fibers such as acetate fibers, vegetable fibers such as cotton and hemp, and animal fibers such as wool) as fibers other than these thermoplastic fibers. Is also good. The wet nonwoven fabric bonded by the preferable thermoplastic fiber is, for example, after forming a fibrous web by a wet method, simultaneously with or after drying the fibrous web, only a heat treatment, or a heat treatment and a pressure treatment. And implementing it. When the heat treatment and the pressure treatment are performed as in the latter case, the heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment. When the heat treatment and the pressure treatment are performed simultaneously, the heating temperature is preferably a temperature lower by about 5 to 120 ° C. than the melting point of the adhesive component of the thermoplastic fiber, and the linear pressure in this case is 0.05 to 4 kN. / Cm, more preferably 0.3 to 3 kN / cm. Further, the heating temperature when the pressure treatment is performed after the heat treatment is preferably 5 to 40 ° C. higher than the melting point of the adhesive component of the thermoplastic fiber, and the linear pressure in this case is 0.05. ４4 kN / cm, more preferably 0.3-3 kN / cm. On the other hand, when only the heat treatment is performed, the heating temperature is preferably 5 to 40 ° C. higher than the melting point of the adhesive component of the thermoplastic fiber. In addition, as the wet nonwoven fabric constituting the auxiliary filtration fiber sheet, the fiber composition was changed (for example, the fiber diameter of the microfiber was changed, the fiber diameter of the adhesive fiber was changed, the compounding amount of the microfiber was changed, Change the blending amount,
Except for combining these, a wet nonwoven fabric produced by a wet method in the same manner as the main filtration nonwoven fabric described above can also be used. Further, after producing two or more wet nonwoven fabrics by a wet method in the same manner as the above-mentioned main filtration nonwoven fabric, the heat treatment and / or pressure treatment is performed on one wet nonwoven fabric to reduce the average flow pore size. The main filtered non-woven fabric is used, and any other wet non-woven fabric is not subjected to any treatment, is subjected to heat treatment and / or pressure treatment to a low degree, or is subjected to fluid flow such as water flow. A wet nonwoven fabric that has been subjected to an entanglement treatment can also be used as an auxiliary filtration fiber sheet. Further, after manufacturing two or more wet nonwoven fabrics by a wet method in the same manner as the above-mentioned main filtration nonwoven fabric, entanglement treatment such as fluid flow (for example, water flow) is performed on only one wet nonwoven fabric. Thus, the average flow pore diameter is increased to form an auxiliary filtration fiber sheet, and this wet nonwoven can be used as the main filtration nonwoven without performing any treatment on another wet nonwoven.

As another auxiliary filtration fiber sheet of the present invention, a melt blown nonwoven fabric is suitable. Since the melt-blown nonwoven fabric is made of melt-blown fibers that have not been subjected to a strong stretching action, the average flow pore size can be easily adjusted by performing the heat treatment and the pressure treatment. This “melt blow non-woven fabric” refers to a non-woven fabric obtained by a melt blow method. For example, a nozzle piece having an orifice diameter of 0.1 to 0.5 mm and a pitch of 0.3 to 1.2 mm is heated to a temperature of 220 to 370 ° C. Heat to 0.02-1.5 g / mi per orifice
The melt blown fibers are discharged at a ratio of n, and the discharged melt blown fibers are produced by allowing a gas having a temperature of 220 to 400 ° C. and a mass ratio of 5 to 2,000 times the fiber discharge amount to act. it can. It is preferable that the melt-blown nonwoven fabric has a mixture of a portion with a large amount of melt-blown fibers and a portion with a small amount of melt-blown fibers in a direction perpendicular to the thickness direction because the filtration flow rate can be increased without impairing the filtration accuracy. The melt-blown nonwoven fabric in which a large portion and a small portion of the melt-blown fiber are mixed is, for example, a nozzle piece that discharges the melt-blown fiber and a support that receives the melt-blown fiber (for example,
Conveyors, rolls, etc.) to increase the distance, or melt-blown fibers between a pair of rolls (support) (particularly, a pair of rolls in which the distance between the rolls, a pair of rolls in which the relative speed between the rolls, By receiving at a pair of rolls at least one of which is an eccentric roll), changing the flow rate of gas acting on the meltblown fiber for each orifice, or changing the flow rate of gas acting on the meltblown fiber over time. be able to. The melt blown fibers can be composed of one or more resin components similar to the thermoplastic fibers constituting the wet nonwoven fabric (auxiliary filtered fiber sheet) as described above. When the meltblown fiber is made of two or more resins, the cross-sectional shape can be a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multi-bimetal type. The melt-blown non-woven fabric may be used as it is, in which the melt-blown fibers discharged from the orifice are received by the support and accumulated, or may be subjected to a heat treatment and / or a pressure treatment in order to adjust the average flow hole diameter. You may use something. When performing the heat treatment and the pressure treatment, the heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment. The heating temperature when the heat treatment and the pressure treatment are performed at the same time is 5 to less than the melting point of the meltblown fiber (when the meltblown fiber is composed of two or more thermoplastic resins having different melting points, the resin having the lowest melting point). The temperature is preferably lower by 120 ° C., and the linear pressure in this case is 0.05 to
It is preferably 4 kN / cm, and 0.3 to 3 kN / c.
m is more preferable. In addition, when the pressure treatment is performed after the heat treatment is performed, the heating temperature is preferably 5 to 120 ° C. lower than the melting point of the melt blown fiber when the melt blown fiber is made of one type of thermoplastic resin. When the melt blown fiber is composed of two or more kinds of thermoplastic resins having different melting points, the temperature is preferably 5 to 40 ° C. higher than the melting point of the resin having the lowest melting point, and the linear pressure in this case is Also 0.05-4k
N / cm is preferable, and 0.3 to 3 kN / cm is more preferable. On the other hand, when only the heat treatment is performed, the heating temperature is 5 degrees below the melting point of the melt-blown fiber when the melt-blown fiber is made of one type of thermoplastic resin.
When the melt-blown fiber is composed of two or more kinds of thermoplastic resins having different melting points, the temperature is preferably 5 to 4 lower than the melting point of the resin having the lowest melting point.
Preferably, the temperature is 0 ° C. higher.

[0022] As another auxiliary filtration fiber sheet of the present invention, a spunbonded nonwoven fabric is suitable. Since the spunbonded nonwoven fabric has an appropriate strength, the processability can be further improved. This “spunbonded nonwoven fabric” refers to a nonwoven fabric obtained by a conventional spunbonding method, and is easily available because it is commercially available. The spunbond fibers constituting this spunbond nonwoven fabric can be composed of one or more resin components similar to the thermoplastic fibers constituting the above-mentioned wet nonwoven fabric (auxiliary filtered fiber sheet). When the spunbond fibers are made of two types of resins, the cross-sectional shape can be a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multi-bimetal type. As this spunbonded nonwoven fabric, a spunbonded nonwoven fabric obtained by a conventional spunbonding method may be used as it is, or a spunbonded nonwoven fabric which has been subjected to a heat treatment and / or a pressure treatment in order to adjust the average flow pore size may be used. May be. When performing heat treatment and pressure treatment,
The heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment. The heating temperature when the heat treatment and the pressure treatment are performed simultaneously is the melting point of the spunbond fiber (the resin having the lowest melting point when the spunbond fiber is made of two or more thermoplastic resins having different melting points). Preferably, the temperature is lower by 5 to 120 ° C., and the linear pressure in this case is 0.3 to 3 kN / c.
m is preferred. Further, the heating temperature when the pressure treatment is performed after the heat treatment is performed is a temperature lower by 5 to 120 ° C. than the melting point of the spunbond fiber when the spunbond fiber is made of one kind of thermoplastic resin. Preferably, when the spunbond fiber is composed of two or more thermoplastic resins having different melting points, the temperature is preferably 5 to 40 ° C. higher than the melting point of the resin having the lowest melting point,
The linear pressure in this case was 0.05 to 4 kN /
cm, more preferably 0.3 to 3 kN / cm. On the other hand, when only the heat treatment is performed, when the spunbond fiber is made of one kind of thermoplastic resin, the heating temperature is 5 to 1 from the melting point of the spunbond fiber.
Preferably, the temperature is lower by 20 ° C., and when the spunbond fiber is composed of two or more thermoplastic resins having different melting points, 5 to 40 ° C. lower than the melting point of the resin having the lowest melting point.
Preferably, the temperature is high.

[0023] As another auxiliary filtration fiber sheet of the present invention, a nonwoven fabric in which meltblown fibers and thermoplastic stretched fibers are mixed (hereinafter, sometimes referred to as "mixed nonwoven fabric") is preferable. Despite having a dense structure, this mixed nonwoven fabric has the features that the filtration flow rate is large, the filtration accuracy is excellent, and the filtration life is long. In addition, there is a feature that the strength is excellent and the workability is excellent. This mixed nonwoven fabric has an average fiber diameter (1
(Average value of fiber diameters at locations of 00 points or more) is 0.1 to
5 to 95 mass% of melt blown fibers of 20 μm and 95 to 100 μm of thermoplastic drawn fibers having an average fiber diameter of 10 to 100 μm
It is preferable that 5 mass% is mixed. The conditions for producing meltblown fibers by this meltblown method are not particularly limited, but they can be produced under the same conditions as those for producing the above-mentioned meltblown nonwoven fabric. The melt blown fibers can be composed of one or more resins similar to the thermoplastic fibers constituting the wet nonwoven fabric (auxiliary filtered fiber sheet) as described above. When the meltblown fibers are made of two or more resins, the cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multi-bimetal type. On the other hand, `` thermoplastic drawn fiber '' is not a fiber drawn by applying air to the fiber extruded from a nozzle, such as melt blown fiber or spunbond fiber, but a fiber extruded from a nozzle by a drawing machine or the like. Fiber drawn by mechanical action. The thermoplastic stretched fiber can be composed of one or more resins similar to the thermoplastic fiber constituting the wet nonwoven fabric (auxiliary filtered fiber sheet) as described above. In addition, the thermoplastic stretched fiber is 2
When composed of more than two kinds of resins, the cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multiple bimetal type. When the thermoplastic stretched fiber is made of two or more resins as described above, even if a resin component that can be bonded (adhesive component) is bonded,
The fiber shape can be maintained by the non-adhesive resin component (non-adhesive component), and an appropriate space by the thermoplastic stretched fiber can be maintained, so that the fluid permeability is excellent. In this case, the difference in melting point between the adhesive component and the non-adhesive component is preferably at least 10 ° C, more preferably at least 20 ° C. Further, the adhesive component of the thermoplastic stretched fiber is 10 points lower than the melting point of the melt-blown fiber (when the melt-blown fiber is composed of two or more resins, the melting point of the resin having the lowest melting point).
The temperature is preferably lower by at least 20 ° C, more preferably lower by at least 20 ° C. The thermoplastic drawn fiber may be a long fiber or a short fiber, but is preferably a short fiber so as to be able to exist in a state of being uniformly mixed with the meltblown fiber.
In the case of short fibers, the fiber length is preferably 5 to 160 mm, and is preferably 25 to 160 to be easily entangled with the melt blown fibers.
More preferably, it is 110 mm. The thermoplastic stretched fiber does not need to be composed of one kind, and two or more kinds of thermoplastic stretched fibers differing in fiber diameter, composition, fiber length and the like may be used. Such a mixed nonwoven fabric can be manufactured, for example, as follows. First, FIG.
As shown in FIG.
The thermoplastic stretched fiber 4 opened by the spreader 3 is supplied to the flow of the melt blown fiber 2 discharged from the apparatus, the two are mixed, and the mixed fiber group is captured by a collector 5 such as a conveyor. Thus, the mixed nonwoven fabric 6 can be formed. Examples of the spreader 3 that supplies the thermoplastic stretched fiber 4 include a card machine and a garnet machine, and the spreader 3 in which a plurality of spread cylinders 31 are housed in a housing 32 as shown in FIG. The thermoplastic stretched fiber 4 collides vigorously with the flow of the meltblown fiber 2 to form a mixed nonwoven fabric 6.
The melt blown fiber 2 and the thermoplastic stretched fiber 4 can be uniformly mixed also in the thickness direction, which is preferable. When the thermoplastic stretched fiber 4 is supplied by the opening device 3, the thermoplastic stretched fiber 4 is thermoplastically drawn from a direction perpendicular to the flow of the meltblown fiber 2 so that the thermoplastic stretched fiber 4 can be uniformly mixed with the meltblown fiber 2. Preferably, fibers 4 are provided. For example, when the flow of the melt blown fibers 2 discharged from the melt blown device 1 is formed in a horizontal direction, the thermoplastic stretched fibers 4 are naturally dropped from above in a direction perpendicular to the flow of the melt blown fibers 2 and supplied. Generally, the flow of the melt-blown fibers 2 discharged from the melt-blow device 1 is preferably in the same direction as the direction in which gravity acts. Therefore, the thermoplastic stretched fibers 4 supplied from the spreader 3 are It is preferable to supply from a direction perpendicular to the direction in which gravity acts. In the spreader 3 of FIG. 2, an air nozzle 33 capable of supplying air is provided so that the thermoplastic stretched fiber 4 can be supplied at such an angle (right angle). By adjusting the angle at which the thermoplastic stretched fibers 4 are supplied to the meltblown fibers 2, the proportion of the thermoplastic stretched fibers 4 in the thickness direction of the mixed nonwoven fabric 6 can be changed. The collector 5 for collecting the fiber group in which the melt blown fiber 2 and the thermoplastic stretched fiber 4 are mixed may be in a roll shape or a net shape. The collecting body 5 is preferably air-permeable so that the mixed nonwoven fabric 6 is not disturbed or scattered by collision with the flowing air flow, and an air flow suction device is preferably provided on the side opposite to the collecting surface. .
The mixed nonwoven fabric thus manufactured may be used as it is, or it is preferable to perform a heat treatment and / or a pressure treatment to adjust the average flow pore size. The heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment. When the heat treatment and the pressure treatment are performed simultaneously, the heating temperature is preferably 5 to 120 ° C. lower than the melting point of the adhesive component of the thermoplastic drawn fiber, and the linear pressure in this case is 0.05 to 4 kN. / C
m, more preferably 0.3 to 3 kN / cm. The heating temperature when the pressure treatment is performed after the heat treatment is preferably 5 to 40 ° C. higher than the melting point of the adhesive component of the thermoplastic stretched fiber, and the linear pressure in this case is 0.1. It is preferably from 0.5 to 4 kN / cm, more preferably from 0.3 to 3 kN / cm. On the other hand, the heating temperature when performing only the heat treatment is 5 to 40 ° C. from the melting point of the adhesive component of the thermoplastic drawn fiber.
Preferably, the temperature is high.

Further, as another auxiliary filtration fiber sheet of the present invention,
Two or more kinds of ultrafine fibers (hereinafter, referred to as “fibers”) which are composed of two or more kinds of resin components and are generated from splittable fibers which can be split by external force.
A nonwoven fabric (hereinafter, referred to as a "divided nonwoven fabric") containing "divided ultrafine fibers" is preferable. This split nonwoven fabric has a high filtration flow rate and excellent filtration accuracy, despite having a dense structure. The two or more types of ultrafine fibers constituting the split nonwoven fabric are composed of two or more types of resin components, and are generated from splittable fibers that can be split by an external force. The splittable fiber is composed of two or more types of resin components so that two or more types of split ultrafine fibers can be generated. As the resin component constituting the splittable fiber, for example, a polyamide resin (for example, nylon 6, nylon 66, etc.), a polyester resin (for example, polyethylene terephthalate, polybutylene terephthalate, etc.), a polyvinylidene chloride resin, or Polyolefin resins (eg, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene copolymer, polypropylene, propylene copolymer, polymethylpentene, methylpentene copolymer, etc.) Can be mentioned. Among these, it is preferable to include a polyolefin-based resin having excellent chemical resistance, and it is more preferable to include only a polyolefin-based resin (for example, a propylene-based resin and an ethylene-based resin). It is preferable that the above-mentioned resin component is arranged such that the splittable fiber can be split by an external force. More specifically, the cross-sectional shape of the splittable fiber is
For example, an orange type as shown in FIGS. 3 to 6 and a multiple bimetal type as shown in FIG. 7 are preferable. In addition, as the external force that can split the splittable fiber,
For example, a fluid flow such as a water flow, a needle, a calendar, a flat press, and the like can be given. Among these, a fluid flow that can not only split but also entangle the fibers is preferable. Such splittable fibers can be produced by a conventional melt spinning method. This split nonwoven fabric contains two or more types of split ultrafine fibers generated from splittable fibers as described above. Therefore, the number of types of the divided microfibers matches the number of resin components constituting the splittable fibers. The cross-sectional shape of the split microfiber varies depending on the arrangement state of the resin components constituting the splittable fiber in the fiber cross-section. When the cross-sectional shape of the splittable fiber is orange as shown in FIG. In the case of an orange type as shown in FIG. 4 which is composed only of triangular divided microfine fibers, it is composed of a substantially triangular divided ultrafine fiber and a substantially elliptical divided ultrafine fiber, and is an orange type as shown in FIG. In the case, it is composed of a substantially triangular divided microfine fiber and a substantially circular divided microfine fiber. In the case of an orange type as shown in FIG. 6, a substantially triangular divided microfine fiber and a substantially circular divided microfine fiber are used. In the case of a multi-bimetal type as shown in FIG. 7, it is composed of only the divided microfine fibers having the substantially eye (I) shape of the alphabet. “Divided extra-fine fibers” in this divided nonwoven fabric has a fiber diameter of 5 μm.
The following fibers are referred to, and more preferably 4 μm or less. The lower limit is not particularly limited, but is 0.01 μm
The degree is appropriate. This split nonwoven fabric contains the above-mentioned split microfine fibers, but can also contain, in addition to the split microfine fibers, undivided splittable fibers that have been the source of the split microfine fibers. By including such splittable fibers, appropriate strength can be imparted to the split nonwoven fabric, and the processability can be further improved. It is preferable that such non-divided splittable fibers are unevenly distributed in the thickness direction of the split nonwoven fabric. In this case, in the thickness direction of the divided nonwoven fabric, a dense region (a region containing the divided ultrafine fibers) and a relatively coarse region (a region containing the divided fibers) are formed, so that the filtration efficiency is good,
The filtration life is long, and the filtration performance is further improved. If the split nonwoven fabric further contains fusible fibers, the fusible fibers are fused, so that the split nonwoven fabric can be given an appropriate strength, so that the processability can be further improved. it can. The fiber diameter of the fusible fiber is 0.5 to 0.5 so as not to impair the filtration performance of the divided ultrafine fibers.
It is preferably 25 μm, more preferably 1 to 20 μm. The fusible fiber may be composed of a single component, but is preferably composed of two or more resin components so that the fiber form can be maintained even after fusion. When composed of two or more resin components, the fiber cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, a multiple bimetal type, or the like. Among these, a core-sheath type, an eccentric type, or a sea-island type having a large amount of resin (fusing component) that can participate in fusion is preferable. This fusible fiber can be composed of the same resin component as the resin component constituting the divided microfine fiber.However, even the divided microfine fiber is melted so that the filtering performance by the divided microfine fiber is not impaired. The melting point of the fusion component of the conductive fiber is preferably lower than the melting point of the divided microfine fiber having the lowest melting point by 10 ° C. or more, more preferably 20 ° C. or more. When the fusible fiber is composed of two or more resin components, the fiber shape of the fusible fiber can be maintained even by heat at the time of fusing the fusible fiber.
The melting point of the resin component (non-fused component) other than the fused component is preferably higher than the melting point of the fused component by 10 ° C. or more, more preferably by 20 ° C. or more. When the split nonwoven fabric further contains hydrophilic fibers, hydrophilicity can be imparted to the split nonwoven fabric, and as a result, a split nonwoven fabric having excellent hydrophilicity can be obtained. When the divided nonwoven fabric is excellent in hydrophilicity as described above, when the processing fluid is water, the water permeability of the cylindrical filter, that is, the filtration flow rate can be improved, and the filtration life can be improved. In the case of a filtration system using a pressurizing pump, it is possible to reduce the pressurizing energy and reduce the load caused by pressurizing the divided nonwoven fabric. The "hydrophilic fiber" refers to a fiber having an official moisture content of 4% or more, and examples thereof include rayon fiber, polynosic fiber, cupra fiber, acetate fiber, and tencel fiber (cellulose fiber obtained by a solvent extraction method). Can be. Such a split nonwoven fabric can be manufactured, for example, as follows. First, a splittable fiber composed of two or more resin components and splittable by an external force is prepared. If necessary, fusible fibers and hydrophilic fibers are also prepared. Next, a fiber web containing splittable fibers is formed by a dry method (for example, a card method, an air lay method, a spun bond method, a melt blow method, etc.) or a wet method. After forming the fiber webs, different or same fiber webs may be laminated. For example, a laminated nonwoven fabric having a dense region and a relatively coarse region in the thickness direction can be manufactured by laminating fiber webs having different compounding ratios of the splittable fibers. Then, by applying a fluid flow such as a water flow to the fiber web, the splittable fibers are split to generate split microfine fibers, and at the same time, the split microfine fibers are entangled to produce a split nonwoven fabric. it can. The processing conditions by a fluid flow applicable in the present invention include, for example, a nozzle diameter of 0.05 to 0.3 mm, a pitch of 0.2 to 3
A fluid flow having a pressure of 1 MPa to 30 MPa may be ejected from a nozzle plate in which nozzles are arranged in one or more rows in mm. Such a fluid stream is ejected at least once onto one or both sides of the fiber web. In addition, when the non-opening portion of the support such as a net or a perforated plate on which the fiber web is placed when processing with the fluid flow is thick, the obtained divided nonwoven fabric also has large holes, and the filtration accuracy is deteriorated. It is preferable to use a support having a non-opening portion having a thickness of 0.25 mm or less. In addition, when the splittable fiber is composed of only the same type of resin component (for example, only composed of a polyolefin resin) and is difficult to split (for example, when a fiber web is formed by a wet method), the splittable fiber is formed. A fluid flow is applied after the resin component is fused, or a fusible fiber is mixed in the fiber web, and a fluid flow is applied after the fusible fiber is fused. When used together, it can be easily divided. In this case, the splitting action of the splittable fiber occurs preferentially, and entanglement of the split ultrafine fiber does not occur much. Therefore, in order to impart strength to the split nonwoven fabric, it is preferable to fuse the resin component and / or the fusible fiber constituting the splittable fiber again. In addition, as described above, the split nonwoven fabric including the splittable fibers that are not split includes, for example, lowering the pressure of the fluid flow, reducing the number of times the fluid flow is applied, and setting the direction in which the fluid flow is applied in one direction. Or, before applying the fluid flow, the resin component and / or fusible fiber constituting the splittable fiber is fused and fixed,
It can be produced by using these methods in combination. The above description relates to a method of manufacturing a split nonwoven fabric by applying a fluid flow to a fiber web and splitting the splittable fiber at the same time. (1) Forming the split nonwoven fabric with a needle and splitting the splittable fiber at the same time. May be
(2) Before forming the fiber web, the fluid flow, the needle,
A fibrous web is formed after splitting the splittable fibers by applying at least one external force such as a calender and a flat press, and then entangled with a fluid flow or a needle,
The fusible fibers may be incorporated by fusing the fusible fibers or bonded with a binder. (3) After bonding the fiber web, a fluid flow, a needle, a calender,
Even if the splittable fiber is split by applying at least one external force of a flat press, a split nonwoven fabric can be manufactured.

[0025] The various auxiliary filtration fiber sheets as described above are in a state of being laminated adjacent to the main filtration nonwoven fabric as described above. This auxiliary filtration fiber sheet may be adjacent to only one surface of the main filtration nonwoven fabric, or may be adjacent to both surfaces.
For example, in the case of a so-called depth-type cylindrical filter, it is sufficient that the auxiliary filtration fiber sheet is adjacent to only one side of the main filtration non-woven fabric. It is preferable that the auxiliary filtration fiber sheet is adjacent to both sides of the sheet. In addition, when the auxiliary filtration fiber sheet is adjacent to both surfaces of the main filtration nonwoven fabric,
The same auxiliary filtration fiber sheet may be adjacent in terms of the average flow hole diameter, or different auxiliary filtration fiber sheets may be adjacent in respect of the average flow hole diameter. In addition, the main filtration nonwoven fabric and the auxiliary filtration fiber sheet may be in a bonded state or in a non-bonded state. As the former state, for example, after laminating the main filtration non-woven fabric and the auxiliary filtration fiber sheet, heat treatment, or the state of bonding and integration by performing heat treatment and pressure treatment, by ultrasonic treatment There are a state of being integrated, a state of being entangled and integrated by a needle or a fluid flow (preferably a water flow), and a state of being bonded and integrated by an adhesive. Further, the auxiliary filtration fiber sheet laminated adjacent to the main filtration nonwoven fabric need not be one kind, and two or more kinds of auxiliary filtration fiber sheets may be laminated. When two or more types of auxiliary filtration fiber sheets are laminated in this manner, it is preferable to laminate the auxiliary filtration fiber sheets in order from the fluid inflow side to the auxiliary filtration fiber sheets having smaller average flow hole diameters. When two or more types of auxiliary filtration fiber sheets are laminated, these auxiliary filtration fiber sheets may be in a connected state or a non-bonded state. Examples of the combined state as the former include, for example, a state of being integrated by bonding by performing a heat treatment or a heat treatment and a pressure treatment, a state of being integrated by ultrasonic treatment, a needle or a fluid flow (preferably a water flow). ) By entangled and integrated,
There is a state of being integrated by bonding with an adhesive.

[0026] The tubular filter of the present invention is arranged around the perforated tube in a state where the main filter non-woven fabric and the auxiliary filter fiber sheet as described above are laminated adjacent to each other. As the arrangement state, for example, a state where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are wound around the perforated tube (so-called depth type), or a case where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are folded and folded. There is a state in which it is arranged around the perforated cylinder in a state (so-called pleated type), or a state having both of these regions.

[0027] In the former depth type cylindrical filter, the main filtration non-woven fabric and the auxiliary filtration fiber sheet are wound around the perforated cylinder, but the number of turns is not particularly limited. The number of turns of the main filtration nonwoven fabric and the auxiliary filtration fiber sheet may be the same or different. That is, the main filtration nonwoven fabric and the auxiliary filtration fiber sheet need not be adjacent to each other over the entire circumference, and may be in a state of being adjacent only in a part of the region. When the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are adjacent only in a part of the region, it is preferable that the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are adjacent on the outflow side of the processing fluid. That is, when the treatment fluid flows in from the outside of the cylindrical filter and flows out, the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are preferably adjacent to each other in the inner layer of the cylindrical filter. When the processing fluid flows in from the inside of the cylindrical filter and flows out, the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are preferably adjacent to each other in the outer layer of the cylindrical filter. The main filtration nonwoven fabric and / or the auxiliary filtration fiber sheet may be wound in any manner, may be wound in a flat wound shape, or may be wound in a spiral shape. Also,
In the case of the depth type, the auxiliary filtration fiber sheet laminated adjacent to the main filtration non-woven fabric does not need to be one type, and two or more types of auxiliary filtration fiber sheets differing in average flow pore diameter are separated from the main filtration non-woven fabric. The layers may be laminated such that the average flow hole diameter increases in order. By laminating in this way,
Further, the filtration life can be extended. More specifically, it is preferable to sequentially stack auxiliary filtration fiber sheets having an average flow pore size larger by about 2 to 40 μm than the main filtration nonwoven fabric. In addition, in a region different from the region where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are wound adjacent to each other, a coarse filtration fiber sheet having an average flow hole diameter larger than the auxiliary filtration fiber sheet by about 2 to 40 μm is wound. Alternatively, folds may be arranged. By arranging such a coarsely-filtered fiber sheet, the filtration life can be further extended.
The coarse filtration fiber sheet may be in a state of being connected to the auxiliary filtration fiber sheet or may be in a state of not being connected.
Examples of the combined state as the former include, for example, a state of being integrated by bonding at least by heat treatment (preferably, a heat treatment and a pressure treatment), a state of being integrated by an ultrasonic seal, a needle and a fluid flow (preferably Are entangled and integrated by a water flow) and bonded and integrated by an adhesive. The coarse filtration fiber sheet may have a larger average flow hole diameter (about 2 to 40 μm) than the auxiliary filtration fiber sheet (when there are two or more types, the auxiliary filtration fiber sheet having the largest average flow hole diameter). A wet nonwoven fabric, a meltblown nonwoven fabric, a spunbonded nonwoven fabric, a mixed nonwoven fabric (however, the average flow pore size is large), a hydroentangled nonwoven fabric, or the like manufactured in the same manner as the auxiliary filtration fiber sheet can be used. Also, besides the area where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are wound,
The main filtration nonwoven fabric and / or the auxiliary filtration fiber sheet may have a region arranged in a folded state.

Another cylindrical filter of the present invention is a pleated cylindrical filter in which a main filtration nonwoven fabric and an auxiliary filtration fiber sheet are folded around a perforated cylinder. The number of folds of the pleated cylindrical filter may be appropriately set depending on the application and required physical properties, and is not particularly limited. In the pleated type cylindrical filter, when the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are folded, the surfaces of the main filtration nonwoven fabric may not only be in close contact with each other and reduce the filtration area, but also the back surfaces may be in contact with each other. Since there is a possibility that the filtration area is reduced due to close contact, it is preferable to laminate the auxiliary filtration fiber sheet on both sides of the main filtration nonwoven fabric. When the auxiliary filtration fiber sheets are laminated on both sides of the main filtration nonwoven fabric in this way, auxiliary filtration fiber sheets having the same average flow pore diameter may be laminated on the front and back surfaces, or auxiliary filtration fiber sheets having different average flow pore diameters. They may be laminated on the front and back surfaces. Also, in the case of the pleated cylindrical filter, the auxiliary filtration fiber sheet laminated adjacent to the main filtration non-woven fabric does not need to be one kind, and two or more kinds of auxiliary filtration fiber sheets differing in the average flow hole diameter are used. May be laminated such that the average flow pore size increases in order from the main filtration nonwoven fabric. By laminating the auxiliary filtration fiber sheets in this way, the filtration life can be further extended. More specifically, it is preferable to laminate the auxiliary filtration fiber sheet so that the average flow pore size increases in order from 2 to 40 μm from the main filtration nonwoven fabric. When two or more types of auxiliary filtration fiber sheets are laminated in this way, they may be laminated on both sides of the main filtration nonwoven fabric, or may be laminated on only one surface, but the auxiliary filtration fiber sheet may be laminated only on one surface of the main filtration nonwoven fabric. Even when two or more types are laminated, it is preferable to laminate one auxiliary filtration fiber sheet on the other surface of the main filtration nonwoven fabric in order to suppress the adhesion between the main filtration nonwoven fabrics.
When two or more types of auxiliary filtration fiber sheets are laminated on only one surface of the main filtration nonwoven fabric, it is preferable that the two or more types of auxiliary filtration fiber sheets are arranged so that the side of the processing fluid flows in. Note that, in a region different from the region where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are arranged in a folded state, a coarse filtration fiber sheet having an average flow hole diameter larger than that of the auxiliary filtration fiber sheet by about 2 to 40 μm. May be provided. By winding such a coarsely-filtered fiber sheet, the filtration life can be further extended. The coarse filtration fiber sheet may be in a state of being connected to the auxiliary filtration fiber sheet or may be in a state of not being connected. As the state of the connection as the former, for example,
At least heat-treated (preferably heat-treated and pressure-treated) bonded and integrated, ultrasonically sealed, needle and fluid flow (preferably water flow) entangled and integrated, bonding And a state of being integrated by bonding with an agent. The coarse filtration fiber sheet may have a larger average flow hole diameter (about 2 to 40 μm) than the auxiliary filtration fiber sheet (when there are two or more types, the auxiliary filtration fiber sheet having the largest average flow hole diameter). A wet nonwoven fabric, a meltblown nonwoven fabric, a spunbonded nonwoven fabric, a mixed nonwoven fabric (however, the average flow pore size is large), a hydroentangled nonwoven fabric, or the like manufactured in the same manner as the auxiliary filtration fiber sheet can be used. Also,
In addition to the region where the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are arranged in a folded state, a region where the main filtration nonwoven fabric and / or the auxiliary filtration fiber sheet is wound may be provided. The fold folding process can be performed by a fold folding machine, and the peak height, the peak interval, and the like can be appropriately set depending on the intended use, desired physical properties, and the like.

[0029] The porous tube constituting the cylindrical filter of the present invention comprises:
Conventionally known materials, for example, those made of metal or plastic can be used. In addition, the cylindrical filter of the present invention has the basic configuration as described above, but prevents the treatment fluid from dissipating by closing both ends of the cylindrical filter with caps, and on the outermost surface of the cylindrical filter, A conventionally employed configuration can be added, for example, by installing a perforated net made of metal or plastic so that the shape of the cylindrical filter can be maintained.

[0030] The cylindrical filter of the present invention can be used for, for example, food / beverage, electronics, pharmaceutical, chemical, water treatment, photography, paint, plating,
It can be used for filtration of fluids such as dyes, liquids used in various manufacturing processes such as machinery and steel, or used liquids.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0032]

EXAMPLES (Example 1) As a sea-island type fiber, poly-L-
A fiber obtained by a composite spinning method (a fineness of 1.5 denier; a sea component composed of lactic acid (hereinafter abbreviated as "PLLA") having 25 island components composed of polypropylene.
Fiber length 3 mm) was prepared. Next, this sea-island type fiber is immersed in an aqueous solution of sodium hydroxide having a temperature of 80 ° C. and 10 mass% for 30 minutes to obtain P which is a sea component of the sea-island type fiber.
The LLA was extracted and removed, and the ultrafine polypropylene fibers (average fiber diameter 1.8 μm, standard deviation 0.15 of the fiber diameter distribution,
Melting point: 172 ° C., cut to a fiber length of 3 mm, unfibrillated, stretched, having substantially the same diameter in the fiber axis direction). On the other hand, as the adhesive fiber, the core component is polypropylene (melting point: 158).
° C), and a sheath-core composite adhesive fiber having a sheath component (adhesive component) of high-density polyethylene (melting point: 131 ° C) (cut to a fiber diameter of 11.8 µm and a fiber length of 10 mm, not fibrillated) , Which has been stretched). Next, the polypropylene ultrafine fibers and the core-sheath composite adhesive fibers were dispersed in a dispersion bath composed of water at a mass ratio of 50:50, and the dispersion was made with a paper machine.
At the same time as drying at 40 ° C., only the adhesive component of the core-sheath composite adhesive fiber is adhered, and the surface density is 38 g / m ² and the thickness is 0.3.
A wet nonwoven fabric (auxiliary filtered nonwoven fabric) having a diameter of 4 mm and an average flow pore diameter of 12.1 μm was produced. Next, this auxiliary filtered nonwoven fabric was passed between calenders (linear pressure: 1.8 kN / cm) set at a temperature of 80 ° C., comprising a metal roll and a resin roll, with a surface density of 38 g / m ² and a thickness of 0.07 mm. A main filtration nonwoven fabric having an average flow pore size of 4.1 μm was produced. The fibers constituting this main filtration nonwoven fabric are arranged two-dimensionally,
The maximum pore size was 1.6 times the average flow pore size. Next, in a state where the main filtered nonwoven fabric was sandwiched between the two auxiliary filtered nonwoven fabrics, a fold folding process was performed with a fold width of 14 mm by a fold folding machine to produce a laminated filter material. Next, the laminated filter material was arranged around a polypropylene porous cylinder so that the number of peaks was 115, and then both ends of the laminated filter material were fused by an ultrasonic welding machine. Then, gaskets are adhered to both end surfaces in the length direction of the perforated cylinder to have an inner diameter of 30 mm, an outer diameter of 69 mm, and a length of 250 mm.
Was manufactured.

Example 2 A nozzle piece having an orifice diameter of 0.2 mm and a pitch of 0.8 mm was heated at a temperature of 320 ° C.
To 0.06 g / min per orifice
At a temperature of 330 ° C. and 70 times the mass of the fiber discharge amount in mass ratio to the discharged melt blown fiber, and the average in the same direction as the direction in which gravity acts. A stream of polypropylene ultrafine fibers 2 (melting point: 160 ° C.) having a fiber diameter of 1.8 μm was formed.
Two opening cylinders 31 as shown in FIG. 2 are housed in a housing 32 in a direction perpendicular to the flow of the polypropylene ultrafine fibers 2, and the core component is supplied from an opening machine 3 having an air nozzle 33. Resin (melting point 16
0 ° C), and the sheath component is polyethylene resin (135).
° C), a core-sheath type thermoplastic stretched short fiber 4 having a fiber diameter of 21.6 µm and a fiber length of 38 mm was supplied and mixed with the polypropylene ultrafine fiber 2. In addition, the mixing mass ratio of the polypropylene ultrafine fiber 2 and the core-sheath thermoplastic stretched short fiber 4 was (polypropylene ultrafine fiber 2) :( core-sheath thermoplastic stretched short fiber 4) = 65: 35. The mixed fiber group was collected by a conveyor belt to form a mixed fiber web. The conveyor belt was formed of a mesh body, and was suctioned from the side opposite to the collecting surface of the belt by a gas suction device to prevent the fibers constituting the mixed fiber web from being disturbed. Then, the mixed fiber web was subjected to a heat treatment for 3 minutes by a dryer at a temperature of 145 ° C.
0 g / m ² , thickness 0.33 mm, average flow hole diameter 13.7
A mixed nonwoven fabric (auxiliary filtered nonwoven fabric) of μm was manufactured. On the other hand, a main filtration nonwoven fabric manufactured in exactly the same manner as in Example 1 was prepared. Then, in exactly the same manner as in Example 1, production of a folded filter material, processing of disposing the laminated filter material around the perforated cylinder, and bonding of a gasket were performed to produce an inner diameter of 30 m.
m, an outer diameter of 69 mm and a length of 250 mm were manufactured as a pleated cartridge filter.

Example 3 A polypropylene spunbonded nonwoven fabric having an area density of 15 g / m ² , a thickness of 0.2 mm, and an average fiber diameter of 37 μm, which was produced by a conventional spunbond method, was prepared. On the other hand, an orifice diameter of 0.3 mm and a pitch of 0.8
The nozzle piece arranged in mm is heated to a temperature of 330 ° C., and melt blown fibers are discharged at a rate of 0.33 g / min per one orifice. At a temperature of 330 ° C. and a mass ratio with respect to the discharged melt blown fibers, The air is applied 220 times the amount of the fiber discharge amount and is accumulated on the conveyor (distance between the nozzle piece and the conveyor: 49 cm).
A meltblown fiber web in which a portion with a large amount of meltblown fiber and a portion with a small amount of meltblown fiber were mixed was manufactured. Next, the melt-blown fiber web was subjected to a heat treatment using a dryer in an atmosphere of 130 ° C., and then subjected to a pressure treatment under a condition of a linear pressure of 0.2 kN / cm to have an areal density of 30 g / m ² and a thickness of 0.1 g / m ² . A polypropylene melt-blown nonwoven fabric having a diameter of 17 mm and an average fiber diameter of 2.1 μm was produced. Next, the polypropylene spunbonded nonwoven fabric and the polypropylene meltblown nonwoven fabric are integrated by an ultrasonic seal, and a composite nonwoven fabric having an area density of 45 g / m ² , a thickness of 0.36 mm, and an average flow pore size of 14.0 μm (auxiliary filtered nonwoven fabric). Was manufactured. On the other hand, a main filtration nonwoven fabric manufactured in exactly the same manner as in Example 1 was prepared. Then, in exactly the same manner as in Example 1, production of a fold-folded laminated filter material (arranged such that the composite nonwoven fabric made of polypropylene and the melt-blown nonwoven fabric is in contact with the main filter nonwoven fabric), and application of the laminated filter material around the perforated cylinder By arranging and bonding the gasket, a pleated cartridge filter having an inner diameter of 30 mm, an outer diameter of 69 mm and a length of 250 mm was manufactured.

Example 4 A polypropylene spunbonded nonwoven fabric (auxiliary filtered nonwoven fabric) manufactured by a conventional spunbonding method and having a surface density of 25 g / m ² , a thickness of 0.24 mm, an average fiber diameter of 37 μm, and an average flow hole diameter of 40 μm. ) Was prepared.
On the other hand, a main filtration nonwoven fabric manufactured in exactly the same manner as in Example 1 was prepared. Then, in exactly the same manner as in Example 1, production of a folded filter material, processing of disposing the laminated filter material around the perforated cylinder, and bonding of a gasket were performed to produce an inner diameter of 30 m.
m, an outer diameter of 69 mm and a length of 250 mm were manufactured as a pleated cartridge filter.

(Example 5) As the sea-island type fiber, the sea component composed of PLLA contained 25 island components composed of polypropylene.
Fibers (fineness: 1.3 denier, fiber length: 3 mm) obtained by the composite spinning method were prepared. Next, the sea-island type fiber is immersed in a 10 mass% sodium hydroxide aqueous solution at a temperature of 80 ° C. for 30 minutes to extract and remove PLLA, which is a sea component of the sea-island type fiber, to obtain a polypropylene ultrafine fiber (average fiber diameter of 1. 4 μm, standard deviation of fiber diameter distribution
12, melting point: 172 ° C., cut to a fiber length of 3 mm, unfibrillated, stretched, having substantially the same diameter in the fiber axis direction). On the other hand, as the adhesive fiber, a core-sheath type composite adhesive fiber (having a fiber diameter of 17 ° C.) in which the core component is made of polypropylene (melting point: 164 ° C.) and the sheath component (adhesive component) is made of low-density polyethylene (melting point: 105 ° C.). 5 μm, cut to a fiber length of 10 mm, not fibrillated, and stretched) were prepared. Next, the ultrafine polypropylene fiber and the core-sheath composite adhesive fiber are dispersed in a dispersing bath composed of water at a mass ratio of 50:50, and the paper is formed by a paper machine. After adhering only the adhesive component of the sheath-type composite adhesive fiber, an area density of 3 was passed through a calender consisting of a metal roll and a resin roll and set at a temperature of 80 ° C. (linear pressure: 1.8 kN / cm).
6g / m ² , thickness 0.07mm, average flow pore size 2.6μ
m of the main filtered nonwoven fabric. The fibers constituting the main filtration nonwoven fabric were two-dimensionally arranged, and the maximum pore size was 1.5 times the average flow pore size. On the other hand, a wet nonwoven fabric (auxiliary filtered nonwoven fabric) exactly as in Example 1 and a polypropylene spunbonded nonwoven fabric (auxiliary filtered nonwoven fabric) exactly as in Example 4 were prepared. Then, in the same manner as in Example 1, production of a fold-folded laminated filter medium (the main filter non-woven cloth was sandwiched between a wet non-woven cloth and a polypropylene spun-bonded non-woven cloth), and the arrangement of the laminated filter medium around the perforated cylinder (polypropylene) Then, the gasket was adhered to produce a pleated cartridge filter having an inner diameter of 30 mm, an outer diameter of 69 mm, and a length of 250 mm.

(Comparative Example 1) Except that the ultrafine polypropylene fiber produced in the same manner as in Example 5 and the core-sheath type composite adhesive fiber similar to that in Example 5 were used in a mass ratio of 7: 3, In the same manner as in Example 5, only the adhesive component of the core-sheath type composite adhesive fiber was adhered, the surface density was 38 g / m ² , and the thickness was 0.2.
A wet nonwoven fabric having a diameter of 8 mm and an average flow pore diameter of 6.9 μm was produced (calendering was not performed). The maximum pore size of this wet nonwoven fabric was 1.7 times the average flow pore size. Then, the wet-type nonwoven fabric was subjected to 0.3 mm diameter nozzles and 0.6 mm pitch from a nozzle plate arranged in a line to form a wet nonwoven fabric.
A stream of water is jetted at a pressure of 3 MPa, and both sides of the wet nonwoven fabric are alternately treated twice, so that the fibers are substantially three-dimensionally entangled, areal density 38 g / m ² , thickness 0.28 mm, average An entangled nonwoven fabric with a flow pore size of 5.3 μm was produced. The maximum pore size of this entangled nonwoven fabric was 2.3 times the average flow pore size. Next, the entangled nonwoven fabric is interposed between a calender composed of a metal roll and a resin roll and set at a temperature of 80 ° C. (linear pressure:
(1.8 kN / cm) to produce a press-bonded nonwoven fabric having an areal density of 38 g / m ² , a thickness of 0.07 mm, and an average flow pore size of 2.1 μm. The fibers constituting this press-bonded nonwoven fabric are three-dimensionally arranged, and the maximum pore size is 2.1% of the average flow pore size.
It was twice. On the other hand, a wet nonwoven fabric (auxiliary filtered nonwoven fabric) similar to that in Example 1 and a polypropylene spunbonded nonwoven fabric (auxiliary filtered nonwoven fabric) similar to Example 4 were prepared. Next, in a state where the press-bonded non-woven fabric was sandwiched between a wet non-woven fabric and a polypropylene spun-bonded non-woven fabric, a fold folding process was performed with a fold width of 14 mm using a fold folding machine to produce a laminated filter material. Then, in exactly the same manner as in Example 1, the laminated filter material was arranged around the perforated tube (arranged so that the spunbonded nonwoven fabric made of polypropylene was on the inside), and the gasket was adhered. A pleated cartridge filter having a length of 69 mm and a length of 250 mm was manufactured.

(Embodiment 6)
Combined nonwoven fabric (auxiliary filtered nonwoven fabric, 320cm length) and Examples
The main filtration nonwoven fabric (60 cm length) manufactured in the same manner as
Prepared. In addition, it is manufactured by the melt blow method.
80g / m^TwoMelt blow with average flow hole diameter of 6μm
Non-woven fabric A (40 cm long), area density 80 g / m^TwoAverage in
Melt blown nonwoven fabric B having a flow pore size of 8 μm (40 cm
Long), and the area density is 80 g / m. ^TwoWith average flow pore diameter of 10μ
melt blown nonwoven fabric C (40 cm long)
I thought. Next, the composite nonwoven fabric (auxiliary filtered nonwoven fabric)
120 cm from the left end and the left end of the main filtration nonwoven fabric
In accordance with the above, the main filtration non-woven fabric is placed on the composite non-woven fabric.
Laminate and then melt melt blow the right end of the main filter nonwoven
-The composite non-woven fabric is aligned with the left end of the non-woven fabric A.
The melt blown nonwoven fabric A is laminated on top of
The right end of the melt-blown nonwoven fabric A and the melt-blown nonwoven fabric B
On the composite nonwoven fabric so that the left edge of the
The melt-blown nonwoven fabric B is laminated, and
The right end of the raw nonwoven fabric B and the left end of the meltblown nonwoven fabric C
Match the melt blown on the composite nonwoven
-The nonwoven fabric C was laminated to produce a filter material laminate. Next
Then, the filter material is laminated around the perforated polypropylene cylinder.
So that the side where the main filtration nonwoven fabric etc. of the body is laminated is on the inside,
From the left end of the filter material laminate, wound in a flat winding shape,
cm, 6.5 cm outside diameter, 25 cm length
Filters were manufactured.

(Comparative Example 2) The same procedure as in Example 6 was repeated, except that the press-bonded nonwoven fabric manufactured in the same manner as in Comparative Example 1 was used instead of the main filtration nonwoven fabric used in Example 6,
cm, an outer diameter of 6.5 cm, and a length of 25 cm were manufactured.

The performances of the cartridge filters of Examples 1 to 6 and Comparative Examples 1 and 2 were examined as follows. 1. Water flow resistance The pressure loss when water was passed through each cartridge filter at a flow rate of 25 L / min was measured and defined as the water flow resistance. The results were as shown in Table 1. 2. Filtration Efficiency A test solution having a concentration of 10 ppm, in which JIS 11 dusts were dispersed in water, was passed through each cartridge filter at a flow rate of 25 L / min with uniform stirring, and the filtrate one minute after passing the water was collected. The number of particles for each particle size contained in the filtrate and the test solution before filtration was measured by a particle size distribution analyzer (COULTER (COUL)
TER) Coulter Multisizer Two (COU)
LTER Multisizer II)). Next, the filtration efficiency at each particle size was calculated from the following equation, and the particle size at which a filtration efficiency of 100% was obtained was defined as the filtration accuracy of the cartridge filter. The results were as shown in Table 1. 2. Filtration efficiency [%] = {(AB) / A} × 100 A: number of particles before filtration, B: number of particles after filtration Filtration life JIS 11 type dust dispersed in water at a predetermined concentration (20 ppm for the pleated cartridge filters of Examples 1 to 5 and Comparative Example 1, and 100 ppm for the depth cartridge filters of Example 6 and Comparative Example 2) The test liquid was passed through each cartridge filter at a flow rate of 25 L / min while stirring uniformly. Pressure loss is measured sequentially for each flow rate, and the differential pressure from the initial pressure is 200 kPa
The total amount of water that had been treated until the water flow became the filtration life. The results were as shown in Table 1.

【table 1】 From Table 1, it was found that both the pleated type cartridge filter and the depth type cartridge filter of the present invention were excellent in low water flow resistance, long filtration accuracy and long filtration life. In addition, the laminated filter medium comprising the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric used in the tubular filter of the present invention can be processed (folded and wound) without damaging the main filtration nonwoven fabric. Was. This means that the main filtration nonwoven fabric was not damaged during processing, from the viewpoint that the filtration life was long and the filtration performance was excellent, without impairing the filtration accuracy in Table 1. Also,
The laminated filter material of the present invention was excellent in handling workability at the time of folding and winding.

[0041]

The cylindrical filter of the present invention has a long filtration life, is excellent in filtration performance, and can be manufactured with good processability (for example, foldability, winding property).

[Brief description of the drawings]

FIG. 1 is a process diagram showing an example of a fiber web manufacturing process.

FIG. 2 is a schematic cross-sectional view of an example of an opening machine.

FIG. 3 is a schematic sectional view of a splittable fiber that can be used in the present invention.

FIG. 4 is a schematic cross-sectional view of another splittable fiber that can be used in the present invention.

FIG. 5 is a schematic cross-sectional view of still another splittable fiber that can be used in the present invention.

FIG. 6 is a schematic cross-sectional view of still another splittable fiber that can be used in the present invention.

FIG. 7 is a schematic cross-sectional view of still another splittable fiber that can be used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melt blow apparatus 2 Melt blow fiber 3 Spreader 31 Spreading cylinder 32 Housing 33 Air nozzle 4 Thermoplastic stretched fiber 5 Collector 6 Mixed nonwoven fabric A Splittable fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D21H 13/12 D21H 13/12 27/08 27/08 F term (Reference) 4D019 AA03 BA13 BB04 BB10 CA03 DA01 DA02 4L047 AA14 AA21 AA27 AA28 AB03 AB08 BA09 BA22 BB09 CA05 CA16 CC12 EA05 4L055 AF16 AF17 AF33 AF44 AF47 BE02 BE20 EA15 EA16 FA11 GA31

Claims (6)

[Claims] 1. A main filtration nonwoven fabric made of fibers having a fiber diameter of less than 20 μm, which are not substantially fibrillated, wherein the fibers are ultrafine fibers having a fiber diameter of 4 μm or less, and fiber diameters of 8 μm or more and 20 μm or more. A main filtration nonwoven fabric having a maximum pore size of not more than twice the average flow pore size, and an auxiliary filtration fiber sheet having an average flow pore size larger than the main filtration nonwoven fabric. A cylindrical filter, wherein the filter nonwoven fabric and the auxiliary filter fiber sheet are arranged adjacent to each other in a state of being laminated adjacent to each other. 2. A value obtained by dividing a standard deviation value of a fiber diameter distribution of the ultrafine fibers by an average value of fiber diameters of the ultrafine fibers is 0.2.
The tubular filter according to claim 1, wherein: 3. The non-woven fabric comprising a wet-laid nonwoven fabric, a melt-blown non-woven fabric, a spun-bonded non-woven fabric, and a mixture of melt-blown fibers and thermoplastic stretched fibers.
It is made of a nonwoven fabric selected from nonwoven fabrics containing two or more types of ultrafine fibers generated from splittable fibers that can be split by external force, comprising at least one kind of resin component,
The cylindrical filter according to claim 1 or 2. 4. The method according to claim 1, further comprising a region around the perforated cylinder, in which the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are arranged in a wound state. A cylindrical filter according to any one of the above. 5. The method according to claim 1, further comprising a region around the perforated cylinder, in which the main filtration nonwoven fabric and the auxiliary filtration fiber sheet are arranged in a folded state. The tubular filter according to any one of the above. 6. The cylindrical filter according to claim 1, further comprising a region in which a coarse filtration fiber sheet having a larger average flow hole diameter than the auxiliary filtration fiber sheet is arranged.