JP4464433B2 - Cylindrical filter - Google Patents

Description

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

  Conventionally, a so-called pleated filter in which a folded filter material is arranged around a perforated tube is known as a filter that can filter solids in a liquid. This pleated filter is suitable because it has a large filtration area and a long filtration life. As a filtering material constituting this pleated filter, a nonwoven fabric obtained by pressurizing a melt blown nonwoven fabric with a heat calender roll is known. Since this filter medium has a fine pore diameter, desired filtration efficiency can be obtained, but there is a problem that clogging is likely to occur due to poor fluid permeability and the filtration life is short. Moreover, since this filter medium has no strength, there is also a problem that the folding processability is poor. In order to improve this folding processability, a filter medium 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 folding processability, the filter medium (melt blown nonwoven fabric) may be damaged by the net. Further, since the net hardly contributes to filtration, it was not fully satisfactory in terms of filtration life. Such a problem may also be found in the case of a so-called depth filter in which a filter medium is wound in a flat shape around a porous cylinder.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cylindrical filter that has a long filtration life and can be manufactured with good workability.

  Another tubular filter of the present invention (hereinafter sometimes referred to as “second tubular filter”) has a main filtration nonwoven fabric made of a melt blown nonwoven fabric, and an average flow pore size larger than that of the main filtration nonwoven fabric, and is substantially a fibril. A wet nonwoven fabric manufactured from fibers having a fiber diameter of less than 20 μm, and the fibers include 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. And an auxiliary filtration nonwoven fabric made of a wet nonwoven fabric having a maximum pore diameter of not more than twice the average flow pore diameter, and is arranged around the perforated cylinder in a state where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are laminated adjacent to each other It has been done. As a result of diligent research, the inventors of the present invention have determined that the main filtration nonwoven fabric made of a melt blown nonwoven fabric has a specific auxiliary filtration nonwoven fabric having an average flow pore size larger than that of the main filtration nonwoven fabric, that is, a fiber diameter that is not substantially fibrillated. It is a wet nonwoven fabric manufactured from fibers of less than 20 μm, and the fibers include 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, and the maximum pore diameter is average It has been found that when an auxiliary filtration nonwoven fabric made of a wet nonwoven fabric having a flow pore size of 2 times or less is combined, the filtration life of the main filtration nonwoven fabric made of a melt blown nonwoven fabric is prolonged without impairing the filtration accuracy. Moreover, since the said auxiliary | assistant filtration nonwoven fabric contains the adhesive fiber which adhere | attached and is excellent also in intensity | strength, it is also discovered that it is excellent also in workability (for example, fold-folding workability, winding property). It was.

  All of the cylindrical filters of the present invention have a long filtration life and are excellent in workability (for example, folding and workability).

The main filtration nonwoven fabric which comprises the 1st cylindrical filter and 2nd cylindrical filter of this invention all consist of melt blown nonwoven fabrics. Since this melt-blown nonwoven fabric is composed of melt-blown fibers that have not been subjected to a strong stretching action, the average flow pore size can be easily adjusted by performing heat treatment and pressure treatment, and demands for various applications Can be easily accommodated. Since the average flow pore size of the main filtration nonwoven fabric is appropriately changed depending on the fluid to be filtered, it is not particularly limited, but is preferably about 0.5 to 40 μm, more preferably about 0.5 to 20 μm. preferable. The “average flow pore size” in the present invention refers to a value obtained by a method defined in ASTM-F316, and is measured by a mean flow point method using, for example, a porometer (Polometer, manufactured by Coulter). Value. This “melt blown nonwoven fabric” refers to a nonwoven fabric produced by the melt blow method. For example, a nozzle piece having an orifice diameter of 0.1 to 0.5 mm and a pitch of 0.3 to 1.2 mm and an orifice disposed at a temperature of 220 to Heat to 370 ° C., and discharge resin at a rate of 0.02 to 1.5 g / min per orifice, and the resin discharge rate is 5 to 220 ° C. at a temperature ratio of 220 to 400 ° C. with respect to the discharged resin. After forming 2,000-fold amount of gas to form meltblown fiber, it can be collected by a collector such as a roll or a conveyor. The melt blown fiber can be composed of a thermoplastic resin, for example, a polyester resin, a polyamide resin, a polyolefin resin (for example, a polyethylene resin, a polypropylene resin, etc.), a polyvinylidene chloride resin, a polyvinyl chloride. It can be composed of one or more types such as a series resin, a polystyrene series resin, a polyacrylonitrile series resin, and a polyvinyl alcohol series resin. Among these resins, polyolefin resins (particularly polypropylene) are preferable because they are excellent in chemical resistance and versatility. In addition, the resin component which comprises a meltblown fiber does not need to be 1 type, and may contain 2 or more types. When the meltblown fiber is composed of two types of resin components, the cross-sectional shape can be, for example, a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, or a multiple bimetal type. This melt blown non-woven fabric may be used as it is by collecting and collecting melt blown fibers discharged from an orifice with a collector, or heat treatment and / or pressure treatment after accumulation in order to adjust the average flow pore size. You may use what performed. 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 in either case is 5 to 120 ° C. lower than the melting point of the meltblown fiber (the resin having the lowest melting point when the meltblown fiber is composed of two or more thermoplastic resins having different melting points). In any case, the linear pressure is preferably 0.3 to 3 kN / cm. The “melting point” in the present invention refers to a temperature that gives a maximum value of a melting endothermic curve obtained by using a differential scanning calorimeter at a temperature rising temperature of 10 ° C./min and raising the temperature from room temperature. When there are two or more maximum values, the highest temperature maximum value is taken as the melting point. The surface density of the melt blown nonwoven fabric of the present invention is preferably about ²⁰ to 200 g / m ² , the thickness is preferably about 0.03 to 1 mm, and the apparent density is 0.2 to 0.6 g / cm. ^It is preferably about ³ .

In the case of the first cylindrical filter of the present invention, an auxiliary filtration nonwoven fabric (hereinafter referred to as “first auxiliary filtration”) having an average flow pore size larger than that of the main filtration nonwoven fabric as described above and in which meltblown fibers and thermoplastic stretch fibers are mixed. Is sometimes laminated adjacent to the main filtration nonwoven fabric as described above. Since this first auxiliary filtration nonwoven fabric contains meltblown fibers produced by the meltblowing method, it has high filtration accuracy and can retain appropriate voids by including thermoplastic stretched fibers, so that the filtration flow rate is increased. can do. Furthermore, since the thermoplastic stretched fiber is contained, there is strength and workability can be improved. The average fiber diameter of the meltblown fibers constituting the first auxiliary filtration nonwoven fabric (average fiber diameter at 100 or more points) is preferably 0.1 to 20 μm, more preferably 0.1 to 10 μm. preferable. Further, such melt blown fibers are preferably contained in the first auxiliary filtration nonwoven fabric in an amount of 5 to 95 mass%, and more preferably in an amount of 15 to 85 mass%. “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 into a circular cross-section when the cross-sectional shape of the fiber is non-circular. Say. The conditions for producing the meltblown fiber by this meltblowing method are not particularly limited, but for example, it can be produced under the following conditions. A nozzle piece having an orifice diameter of 0.1 to 0.5 mm and an orifice arranged at a pitch of 0.3 to 1.2 mm is heated to a temperature of 220 to 370 ° C., and 0.02 to 1.5 g / min per orifice. The resin can be discharged at a rate of 5%, and a gas having a temperature of 220 to 400 ° C. and a mass ratio of 5 to 2,000 times the amount of discharged fiber can be applied to the discharged resin. The resin component constituting the melt blown fiber may be a thermoplastic resin, and can be exactly the same as the resin constituting the melt blown fiber constituting the main filtration nonwoven fabric described above. For the same reason, a polyolefin resin (particularly, (Polypropylene) is preferred. In addition, the resin component which comprises a meltblown fiber does not need to be 1 type, and can also contain 2 or more types. When the meltblown fiber is made of two or more 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. On the other hand, "thermoplastic drawn fiber" is not a fiber drawn by applying air to the fiber extruded from the nozzle, such as a melt blown fiber or a spunbond fiber, but a fiber extruded from the nozzle, such as a drawing machine. A fiber drawn by mechanical action. The average fiber diameter of the thermoplastic stretched fiber is preferably 10 to 100 μm, and more preferably 15 to 80 μm. Moreover, it is preferable that 5-95 mass% is contained in such a 1st auxiliary | assistant filtration nonwoven fabric, and, as for such a thermoplastic stretch fiber, it is more preferable that 15-85 mass% is contained. In addition, the average fiber diameter of the thermoplastic stretched fiber refers to the average value of the fiber diameters at 100 or more points when the thermoplastic stretched fiber is a long fiber, and when the thermoplastic stretched fiber is a short fiber. Means the average value of the fiber diameters of 100 or more thermoplastic stretched fibers. This thermoplastic stretched fiber can be composed of one or more kinds of resins similar to the thermoplastic resin constituting the melt blown fiber as described above. In addition, when a thermoplastic stretch fiber consists of two or more types of resin, 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, a multiple bimetal type, for example. In this way, when the thermoplastic stretched fiber is composed of two or more kinds of resins, even if a resin component (adhesive component) that can be bonded is bonded, the fiber shape can be maintained by the resin component (non-adhesive component) that is not bonded. In addition, since an appropriate space can be maintained by the thermoplastic stretched fiber, it is excellent in fluid permeability. In this case, the melting point difference between the adhesive component and the non-adhesive component is preferably 10 ° C. or higher, and more preferably 20 ° C. or higher. The adhesive component of the thermoplastic stretched fiber is preferably 10 ° C. or more lower than the melting point of the meltblown fiber (if the meltblown fiber is made of two or more resins, the melting point of the resin having the lowest melting point), More preferably, it is lower. The thermoplastic drawn fibers may be long fibers or short fibers, but are preferably short fibers so that they can be present in a state of being uniformly mixed with meltblown fibers. In the case of a short fiber, the fiber length is preferably 5 to 160 mm, and more preferably 25 to 110 mm so as to be easily entangled with the meltblown fiber. This thermoplastic drawn fiber does not need to consist of one type, and two or more types of thermoplastic drawn fibers that differ in terms of fiber diameter, composition, fiber length, etc. may be used in combination. Such a 1st auxiliary filtration nonwoven fabric can be manufactured as follows, for example. First, as shown in FIG. 1, the thermoplastic stretched fiber 4 opened by the fiber opening machine 3 is supplied to the flow of the meltblown fiber 2 formed by the meltblowing apparatus 1 under the conditions as described above, and both are supplied. After mixing, the mixed fiber group can be collected by a collecting body 5 such as a conveyor to form the first auxiliary filtration nonwoven fabric 6. Examples of the opening machine 3 for supplying the thermoplastic stretched fiber 4 include a card machine and a garnet machine, and the opening machine 3 in which a plurality of opening cylinders 31 as shown in FIG. The thermoplastic stretched fibers 4 can collide with the flow of the meltblown fibers 2 vigorously, and the meltblown fibers 2 and the thermoplastic stretched fibers 4 can be mixed evenly in the thickness direction of the first auxiliary filtration nonwoven fabric 6. Therefore, it is preferable. Further, when the thermoplastic stretched fiber 4 is supplied by the fiber opening machine 3, the thermoplastic stretched fiber 4 is thermoplastically stretched from a direction perpendicular to the flow of the meltblown fiber 2 so that the thermoplastic stretched fiber 4 can be uniformly mixed with the meltblown fiber 2. It is preferable to supply the fibers 4. For example, when the flow of the meltblown fiber 2 formed by the meltblown apparatus 1 is in the horizontal direction, the thermoplastic stretched fiber 4 may be naturally dropped and supplied from above in a direction perpendicular to the flow of the meltblown fiber 2. In general, the flow direction of the meltblown fiber 2 formed by the meltblown apparatus 1 is preferably the same as the direction in which gravity acts, so that the thermoplastic stretched fiber 4 supplied from the opening machine 3 It is preferable to supply from a direction perpendicular to the direction of action. The opening machine 3 in FIG. 2 includes an air nozzle 33 that can supply air so that the thermoplastic stretched fiber 4 can be vigorously supplied even at such an angle (right angle). In addition, the abundance ratio of the thermoplastic stretched fibers 4 in the thickness direction of the first auxiliary filtration nonwoven fabric 6 can be changed by adjusting the angle at which the thermoplastic stretched fibers 4 are supplied to the meltblown fibers 2. The collecting body 5 for collecting the fiber group in which the melt blown fiber 2 and the thermoplastic stretched fiber 4 are mixed may be in a roll shape or a conveyor shape. In order to prevent the first auxiliary filtration nonwoven fabric 6 from being disturbed or scattered by the collision with the airflow, the collector 5 is preferably breathable, and an airflow suction device is provided on the side opposite to the collection surface. Is preferred. The first auxiliary filtration nonwoven fabric produced in this manner may be used as it is, but it is preferable to adjust the average flow pore size by carrying out heat treatment and / or pressure treatment. The heat treatment and the pressure treatment may be performed simultaneously, or the pressure treatment may be performed after the heat treatment is performed. The heating temperature when the heat treatment and the pressure treatment are performed simultaneously is preferably 5 to 120 ° C. lower than the melting point of the adhesive component of the thermoplastic stretched fiber, and the linear pressure in this case is 0.1 to 4 kN. / cm is preferred. On the other hand, 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. It is preferably 1 to 4 kN / cm. In addition, when only heat processing is implemented, it is preferable that the heating temperature is 5-40 degreeC higher than melting | fusing point of the adhesive component of a thermoplastic stretched fiber. The first auxiliary filtration nonwoven fabric in the first tubular filter of the present invention is a mixture of melt blown fibers and thermoplastic stretch fibers, but the average flow pore size is larger than the average flow pore size of the main filtration nonwoven fabric. is there. Therefore, it is possible to extend the filtration life of the main filtration nonwoven fabric by filtering a large solid with the first auxiliary filtration nonwoven fabric and reducing the load on the main filtration nonwoven fabric. Moreover, adhesion of main filtration nonwoven fabrics can be suppressed by the first auxiliary filtration nonwoven fabric, and the filtration performance of the main filtration nonwoven fabric can be sufficiently exhibited. Since the degree of the average flow pore size of the first auxiliary filtration nonwoven fabric is appropriately changed depending on the fluid to be filtered and the like, the average flow pore size of the first auxiliary filtration nonwoven fabric is not particularly limited. It is preferably about 2 to 40 μm larger than the average flow pore size, more preferably about 2 to 20 μm. 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. Therefore, the average flow pore size of the first auxiliary filtration nonwoven fabric is The thickness is preferably about 2.5 to 80 μm, more preferably about 2.5 to 60 μm, and still more preferably about 2.5 to 40 μm. The surface density of the first auxiliary filtration nonwoven fabric of the present invention is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is 0.05 to 0.00. It is preferably about 7 g / cm ³ .

The second tubular filter of the present invention was produced from the main filtration nonwoven fabric as described above and fibers having a mean flow pore size larger than the main filtration nonwoven fabric and not substantially fibrillated and having a fiber diameter of less than 20 μm. It is a wet non-woven fabric, and the fiber includes an ultrafine fiber having a fiber diameter of 4 μm or less and a bonded adhesive fiber having a fiber diameter of 8 μm or more and less than 20 μm, and has a maximum pore diameter that is not more than twice the average flow pore diameter. An auxiliary filtration nonwoven fabric made of a nonwoven fabric (hereinafter sometimes referred to as “second auxiliary filtration nonwoven fabric”) is in a laminated state. Therefore, the filter life can be extended by filtering a large solid with the second auxiliary filtration nonwoven fabric and reducing the load on the main filtration nonwoven fabric. Moreover, adhesion between the main filtration nonwoven fabrics can be suppressed by the second auxiliary filtration nonwoven fabric, and the filtration performance of the main filtration nonwoven fabric can be sufficiently exhibited. Further, since the second auxiliary filtration nonwoven fabric has a narrow pore size distribution, the filtration accuracy of the cylindrical filter can be further improved. The degree of the average flow pore size of the second auxiliary filtration nonwoven is appropriately changed depending on the fluid to be filtered, and is not particularly limited. However, the average flow pore size of the second auxiliary filtration nonwoven is not limited to that of the main filtration nonwoven. It is preferably about 2 to 40 μm larger than the average flow pore size, more preferably about 2 to 20 μm. 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. Therefore, the average flow pore size of the second auxiliary filtration nonwoven fabric is The thickness is preferably about 2.5 to 80 μm, more preferably about 2.5 to 60 μm, and still more preferably about 2.5 to 40 μm. The surface density of the second auxiliary filtration nonwoven fabric of the present invention is preferably about 5 to 200 g / m ² , the thickness is preferably about 0.005 to ² mm, and the apparent density is 0.05 to 0.00. It is preferably about 7 g / cm ³ . The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is manufactured from fibers that are not substantially fibrillated so as not to impair the uniform dispersibility of the fibers. This “non-fibrillated fiber” means a fiber in which a plurality of fibers are not bonded, for example, a fiber in which an infinite number of fibers branch from one fiber (for example, a fiber beaten by a beater, Pulp) or a fiber in which a plurality of fibers are already bonded and in a network state (for example, a fiber obtained by flash spinning). The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is a fiber having a fiber diameter of less than 20 μm (preferably, so as not to disturb the fiber arrangement due to the presence of thick fibers and to form a large aperture diameter). , Fibers having a fiber diameter of 18 μm or less). More specifically, it includes 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 is uniformly dispersed so as to form a uniform pore diameter, and the fiber diameter is 4 μm 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, more preferably 0.3 μm or more, still more preferably 0.5 μm or more, 0 Most preferably, it is 75 μm or more. It is preferable that the fiber diameters of the ultrafine fibers are substantially the same so that a uniform pore diameter can be formed by the ultrafine fibers as described above. 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). In addition, since the standard deviation value becomes 0 when the fiber diameters of the ultrafine fibers are all the same, the lower limit of 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 0. The “average value of fiber diameter” of the ultrafine fibers is obtained by taking an electron micrograph of the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) and measuring the fiber diameter of 100 or more (n) ultrafine fibers in the electron micrograph. And the value which averaged the measured fiber diameter is said. The “standard deviation value” of the ultrafine fiber is a value calculated from the measured fiber diameter (χ) by the following formula.
Standard deviation = {(nΣχ ² − (Σχ) ² ) / n (n−1)} ^1/2
Here, n means the number of measured ultrafine fibers, and χ means the fiber diameter of each ultrafine fiber. In addition, when there are two or more types of ultrafine fibers having a fiber diameter of 4 μm or less, it is preferable that the above relationship is established for each ultrafine fiber. Moreover, it is preferable that the ultrafine fibers have substantially the same diameter in the fiber axis direction of the ultrafine fibers so that a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a uniform pore diameter can be formed. Such ultrafine fibers having substantially the same fiber diameter, or ultrafine fibers having substantially the same diameter in the fiber axis direction, for example, regulate the die into the sea component at the spinneret and extrude the island component. It can be obtained by removing the sea component of the sea-island fiber obtained by the composite spinning method. In addition, it is almost the same by removing the sea component of the sea-island type fiber obtained by the method of spinning after mixing the resin constituting the island component and the resin constituting the sea component, which is generally referred to as a mixed spinning method. It is difficult to obtain an ultrafine fiber having a fiber diameter or an ultrafine fiber having substantially the same diameter in the fiber axis direction. The resin constituting this ultrafine fiber is not particularly limited. For example, nylon 6, nylon 66, polyamide such as nylon copolymer, polyethylene terephthalate, polyethylene terephthalate copolymer, polybutylene terephthalate, polybutylene Polyester such as terephthalate copolymer, polyethylene, polypropylene, poly-4-methyl-1-pentene, polyolefin such as olefin copolymer, synthetic resin such as polystyrene, polyurethane, vinyl polymer, etc. Can do. It should be noted that if the ultrafine fiber includes a resin component (hereinafter, sometimes referred to as “adhesive component”) that can participate in adhesion, and the adhesive component is adhered, the ultrafine fiber can be reliably fixed. This is a preferred embodiment because it does not fall off or fluff. When adhering these ultrafine fibers, the ultrafine fibers can be composed only of an adhesive component made of resin as described above, or an adhesive component and a component having a melting point higher than that of the adhesive component (hereinafter referred to as “non-adhesive”). It may also be composed of two or more types of resin components. When the ultrafine fiber is composed of two or more types of resin components including an adhesive component and a non-adhesive component as in the latter, the fiber shape is maintained even when the ultrafine fiber is bonded, which is the original function of the ultrafine fiber. This is more preferable because it does not prevent the formation of a uniform pore diameter. When the ultrafine fiber is composed of two or more kinds of resin components, the adhesive component occupies at least a part of the surface of the ultrafine fiber so that it can participate in the adhesion (the cross-sectional shape of the ultrafine fiber is, for example, a core-sheath type) , Eccentric type, side-by-side type, sea-island type, orange type, multiple bimetal type), and the entire surface of the ultrafine fiber (the cross-sectional shape of the ultrafine fiber is, for example, a core-sheath type, an eccentric type, or a sea-island type) It is more preferable that the adhesive component occupies. On the other hand, the non-adhesive component is preferably higher than the melting point of the adhesive component by 10 ° C. or higher and more preferably 20 ° C. or higher so that the fiber shape can be maintained. In addition, it is preferable that the non-adhesive component has a melting point higher by 10 ° C. or more than the melting point of the adhesive component of the adhesive fiber described later, so that the fiber shape can be maintained by heat when adhering the adhesive fiber described later. It is more preferable to have a melting point that is 20 ° C. or higher. This fine fiber composed of two or more kinds of resin components including an adhesive component and a non-adhesive component is a cross-sectional shape as described above as a die for extruding an island component when spinning by a conventional composite spinning method. (For example, core-sheath type, eccentric type, side-by-side type, sea-island type, orange type, multiple bimetal type, etc.) can be obtained by spinning sea-island type fibers and removing sea components. it can. In addition, the ultrafine fiber may have performances such as crimping and splitting properties in addition to the adhesiveness as described above. As the former ultrafine fiber having a crimped expression, an ultrafine fiber in which two or more kinds of resin components are arranged so that the cross-sectional shape is an eccentric type or a side-by-side type can be used, and the latter ultrafine fiber has a cross-sectional shape. Ultrafine fibers in which two or more types of resin components are arranged can be used, such as a sea-island type, an orange type, or a multiple bimetal type. As will be described later, the ultrafine fibers are preferably short fibers having a high degree of freedom (fiber length is 30 mm or less) so that they can be uniformly dispersed. However, when ultrafine fibers or sea-island fibers are cut, If each other or island components are pressure-bonded, it will be in the same state as fibrillated fibers, so it is necessary to use ultrafine fibers or sea-island fibers that are difficult to bond between ultrafine fibers or island components when cutting. preferable. Examples of such ultrafine fibers or sea-island fibers that are difficult to press-bond include ultrafine fibers with high crystallinity (island components in the case of sea-island fibers). More specifically, when the ultrafine fiber (island component in the case of sea-island type fibers) contains polymethylpentene or syndiotactic polystyrene, or contains polypropylene, the melting point of the polypropylene is 166 ° C. or higher. When it is (preferably 168 ° C. or higher), it is difficult to press-bond. On the other hand, the adhesive fibers are thicker than the ultrafine fibers and have a fiber diameter of 8 μm or more so that the ultrafine fibers are bonded to fix the ultrafine fibers and can impart strength to the second auxiliary filtration nonwoven fabric (wet nonwoven fabric). Further, the fiber diameter is less than 20 μm so that the arrangement of the ultrafine fibers is not disturbed by the adhesive fibers to form a large aperture diameter. A more preferable fiber diameter of the adhesive fiber is 8 μm or more and 18 μm or less. This adhesive fiber may be composed of a single component, but it is preferably composed of two or more kinds of resin components so that the fiber form is maintained and the strength is excellent even after bonding. As an arrangement state of the two or more types of resin components, for example, the fiber cross-sectional shape may be a core-sheath type, an eccentric type, a side-by-side type, a sea-island type, an orange type, a multiple bimetal type, or the like. Among these, a resin that can participate in adhesion, that is, a core-sheath type, an eccentric type, or a sea-island type with many adhesive components is preferable. This adhesive fiber can be composed of the same resin as the ultrafine fiber, but when the ultrafine fiber is not bonded, the adhesive fiber is not melted by heat when the adhesive fiber is bonded. The melting point of the adhesive component is preferably 10 ° C. or more lower than the melting point of any resin component of the ultrafine fiber, and more preferably 20 ° C. or more. On the other hand, when the adhesive component of the ultrafine fiber is also adhered, the adhesive component of the adhesive fiber and the adhesive component of the ultrafine fiber can be simultaneously performed so that the adhesion of the adhesive component of the adhesive fiber and the adhesive component of the ultrafine fiber can be performed simultaneously. And the melting point difference is preferably within 35 ° C., more preferably within 30 ° C. The melting point of the adhesive component of the adhesive fiber and the melting point of the adhesive component of the ultrafine fiber (if there are multiple types of ultrafine fibers, the melting point of the resin component having the melting point closest to the adhesive component of the adhesive fiber) When the difference is 10 ° C. or more and 35 ° C. or less, the adhesive component of the ultrafine fiber can be adhered, or the ultrafine fiber can be not adhered. When the ultrafine fiber includes an adhesive component and a non-adhesive component, the melting point of the adhesive component of the adhesive fiber is 10 ° C. higher than the melting point of the non-adhesive component of the ultrafine fiber so that the ultrafine fiber can maintain the fiber shape. It is preferably lower, more preferably 20 ° C. or higher. Furthermore, when the adhesive fiber is composed of two or more types of resin components, resin components other than the adhesive component (non-adhesive) can be maintained by the heat at the time of bonding the adhesive fiber. The melting point of the component) is preferably 10 ° C. or higher, more preferably 20 ° C. or higher than the melting point of the adhesive component. Such an adhesive fiber can be easily spun by a conventional composite spinning method or a mixed spinning method. This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) includes the above-described ultrafine fibers and adhesive fibers. The mass ratio of these fibers varies as appropriate depending on the specific application and required physical properties of the cylindrical filter, but is preferably (ultrafine fiber) :( adhesive fiber) = 30 to 70:70 to 30. If the amount of extra fine fibers is 30 mass% or more, a second auxiliary filtration nonwoven fabric (wet non-woven fabric) having a narrow pore size distribution can be obtained. On the other hand, if the amount of adhesive fibers is 30 mass% or more, the extra fine fibers are sufficiently fixed. Therefore, it is difficult for the fine fibers to fall off, and the wet nonwoven fabric can be given strength. A more preferable mass ratio is (ultrafine fiber) :( adhesive fiber) = 35 to 65:65 to 35. In addition, these mass ratios say the ratio with respect to the whole mass of a 2nd auxiliary | assistant filtration nonwoven fabric (wet nonwoven fabric). This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is a fiber having a fiber diameter of more than 4 μm and less than 8 μm (hereinafter sometimes referred to as “intermediate fiber diameter fiber”) in addition to the ultrafine fibers and adhesive fibers as described above. It can also be included. The content of the intermediate fiber diameter is preferably 40% by mass or less, more preferably 30% by mass or less from the relationship with the ultrafine fiber and the adhesive fiber. That is, it is preferable that (fine fiber) :( adhesive fiber) :( intermediate fiber diameter fiber) = 30 to 70:70 to 30: 0 to 40, (extra fine fiber) :( adhesive fiber) :( intermediate) (Fiber diameter fiber) = 35 to 65:65 to 35: 0 to 30 is more preferable. The fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting this second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be in an unstretched state, but as excellent in strength, A fiber obtained by drawing a fiber extruded from a nozzle by a mechanical action such as a drawing machine is preferable. In addition, the fiber length of the fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is not particularly limited. Since the degree of freedom is high and the fibers can be uniformly dispersed, the fiber length of the fibers constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is preferably 0.5 to 30 mm. Preferably, fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) are cut to a fiber length of 0.5 to 30 mm. The “fiber length” in the present invention refers to the length obtained by JIS L 1015 (chemical fiber staple test method) B method (corrected staple diagram method). This second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is composed of the fibers as described above, and has a maximum pore size of not more than twice the average flow pore size (more preferably 1.9 times or less) and a narrow pore size distribution. . Ideally, the maximum pore size is one time the average flow pore size, that is, the total pore size is the same. The “maximum pore diameter” refers to a value measured by a bubble point method using a porometer (Polometer, manufactured by Coulter). When the fibers (for example, ultrafine fibers, adhesive fibers, intermediate fiber diameter fibers, etc.) constituting the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) are arranged substantially two-dimensionally, the arrangement of the fibers is regular. Therefore, the pore size distribution can be further narrowed, which is a preferable mode. In addition, “the fibers are arranged substantially two-dimensionally” means a state where the fibers oriented in the thickness direction are not substantially arranged. For example, for a fiber web formed by a wet method Thus, it is a state that can be obtained in the case of bonding only by adhesion without causing a fluid flow such as a water flow to act. Such a second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be produced, for example, as follows. First, at least ultrafine fibers and adhesive fibers that are not substantially fibrillated are prepared. As the ultrafine fibers, fibers having substantially the same fiber diameter, that is, a 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 0.2 or less (preferably 0.18 or less). , 0 or more) makes it easy to produce an auxiliary filtration nonwoven fabric (wet nonwoven fabric) having a narrow pore size distribution. In addition, it is preferable that fiber lengths, such as an ultrafine fiber and an adhesive fiber, are 0.5-30 mm. Moreover, when the fiber (for example, ultrafine fiber etc.) which is hard to press-fit when cut | disconnecting is used, the dispersibility of a fiber will improve and it will become easy to manufacture the 2nd auxiliary filtration nonwoven fabric (wet nonwoven fabric) with a narrow hole diameter distribution. Then, using these fibers, a fiber web is formed by a conventional wet method. Since the fibers used are not substantially fibrillated, the fibers can be evenly dispersed in the water, which is a dispersion bath, and the fibers that make up the fibers are not entangled with each other. The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be produced. When forming this fiber web, a thickener is added to maintain a uniform dispersion state of the fiber, or a surfactant is added to increase the affinity between water and the fiber (particularly the affinity for water). A second auxiliary filtration nonwoven fabric (wet nonwoven fabric) with a narrow pore size distribution, which improves the dispersibility of the fibers by adding an antifoaming agent to remove bubbles generated by stirring or the like. ) Is easier to manufacture. Next, simultaneously with or after drying the fiber web, the adhesive component of the adhesive fiber is allowed to adhere (in some cases, the adhesive component of the ultrafine fiber can also be adhered), and heat (if necessary, pressure) is applied. The second auxiliary filtration nonwoven fabric (wet nonwoven fabric) can be obtained by adhering the adhesive component of the adhesive fiber (in some cases, the adhesive component of the ultrafine fiber). In this way, when the second auxiliary filtration nonwoven fabric (wet nonwoven fabric) is produced by adhering the adhesive component of the adhesive fiber (in some cases, the adhesive component of the ultrafine fiber) without causing a fluid flow such as a water flow to act on the fiber web, Since it is in the state arrange | positioned two-dimensionally, it becomes easy to manufacture the 2nd auxiliary filtration nonwoven fabric (wet nonwoven fabric) with a narrow hole diameter distribution.

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

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

  The former depth-type cylindrical filter has a region in which the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound around the porous cylinder, but the number of windings is not particularly limited. The number of windings of the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric may be the same or different. That is, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric do not have to be adjacent over the entire circumference, and may be in a state of being adjacent only in a part of the region. When the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are adjacent to each other only in a part of the region, the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are preferably adjacent to each other on the outflow side of the processing fluid. That is, when the processing fluid flows in from the outside of the cylindrical filter and flows out to the inside, it has a region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently in the inner layer of the cylindrical filter. Is preferred. Further, when the processing fluid flows in from the inside of the cylindrical filter and flows out to the outside, it has a region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently in the outer layer of the cylindrical filter. Is preferred. The main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric may be wound in any manner, may be wound in a flat winding shape, or may be wound in a spiral shape. Further, in the case of the depth type, the auxiliary filtration nonwoven fabric laminated adjacent to the main filtration nonwoven fabric does not need to be one type, and two or more types of auxiliary filtration nonwoven fabrics different in terms of average flow pore diameter are used. It is preferable that the auxiliary filtration nonwoven fabric having a large average flow pore diameter is laminated in order from the fluid inflow side. In this way, the auxiliary filtration nonwoven fabric is laminated, whereby the filtration life can be further increased. More specifically, it is preferable that an auxiliary filtration nonwoven fabric having an average flow pore size larger by about 2 to 40 μm than the main filtration nonwoven fabric is laminated in order from the main filtration nonwoven fabric to the fluid inflow side. In addition, a coarse filtration fiber sheet having an average flow pore size larger than the auxiliary filtration nonwoven fabric by about 2 to 40 μm is wound or wound in a region different from the region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are wound adjacently. You may have the area | region arrange | positioned in the folded state. By having such a region where the coarse filter fiber sheet is disposed, the filtration life can be further extended. This coarse filter fiber sheet may be in a state of being bonded to the auxiliary filtration nonwoven fabric or in a state of not being bonded. Examples of the combined state as in the former include, for example, a state in which at least a heat treatment (preferably heat treatment and pressure treatment) is bonded and integrated, a state in which an ultrasonic seal is integrated, a needle and a fluid flow (preferably a water flow) ) Intertwined and integrated, and adhesive and integrated with an adhesive. The coarse filtration fiber sheet may be any sheet having a larger average flow pore size (about 2 to 40 μm) than the auxiliary filtration nonwoven fabric (the auxiliary filtration nonwoven fabric having the largest average flow pore size when there are two or more types). Wet non-woven fabric manufactured to have a large average flow pore size in the same manner as filtration nonwoven fabric, Non-woven fabric in which melt blown fiber and thermoplastic stretched fiber are mixed to have a large average flow pore size in the same manner as auxiliary filtration non-woven fabric, It can be a melt blown nonwoven fabric manufactured to have a large average flow pore size, or a spunbond nonwoven fabric manufactured to have a large average flow pore size in the same manner as the filtration nonwoven fabric. Moreover, you may have the area | region arrange | positioned in the state by which the main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric were folded in addition to the area | region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric were wound.

  Another tubular filter of the present invention is a pleated tubular filter having a region disposed around a porous tube in a state in which a main filtration nonwoven fabric and an auxiliary filtration nonwoven fabric are folded. The number of folds of the pleated cylindrical filter may be appropriately set depending on the application and necessary physical properties, and is not particularly limited. In this pleated tubular filter, when the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are folded, not only the surfaces of the main filtration nonwoven fabric may be brought into close contact with each other, but also the filtration area may be reduced. It is preferable that the auxiliary filtration nonwoven fabric is laminated on both surfaces of the main filtration nonwoven fabric because there is a possibility that the filtration area will be reduced due to close contact. Thus, when the auxiliary filtration nonwoven fabric is laminated | stacked on both surfaces of the main filtration nonwoven fabric, the auxiliary filtration nonwoven fabric of the same average flow volume pore diameter may be laminated | stacked on the front and back of the main filtration nonwoven fabric, or auxiliary filtration of a different average flow volume pore diameter The nonwoven fabric may be laminated | stacked on the front and back of the main filtration nonwoven fabric. Also, in the case of a pleated cylindrical filter, the auxiliary filtration nonwoven fabric laminated adjacent to the main filtration nonwoven fabric does not need to be one type, and there are two or more types of auxiliary filtration nonwoven fabrics that differ in terms of average flow pore size. In addition, the auxiliary filtration nonwoven fabric having a larger average flow pore size may be laminated in order from the main filtration nonwoven fabric to the fluid inflow side. In this way, the auxiliary filtration nonwoven fabric is laminated, whereby the filtration life can be further increased. More specifically, it is preferable that an auxiliary filtration nonwoven fabric having an average flow pore size of about 2 to 40 μm is laminated in order from the main filtration nonwoven fabric to the fluid inflow side. In this way, when two or more types of auxiliary filtration nonwoven fabrics are laminated, they may be laminated on both sides of the main filtration nonwoven fabric, or may be laminated only on one side, but only on one side of the main filtration nonwoven fabric. Even when two or more kinds of nonwoven fabrics are laminated, it is preferable that one auxiliary filtration nonwoven fabric is laminated on the other surface of the main filtration nonwoven fabric in order to suppress adhesion between the main filtration nonwoven fabrics. In addition, when two or more types of auxiliary filtration nonwoven fabrics are laminated on only one side of the main filtration nonwoven fabric, the side on which the two or more types of auxiliary filtration nonwoven fabrics are laminated is the inflow side of the processing fluid. Is preferred. In addition, a coarse filtration fiber sheet having an average flow pore size larger than the auxiliary filtration nonwoven fabric by about 2 to 40 μm is wound in a region different from the region where the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are arranged in a folded state. You may have the turned area. When such a coarse filter fiber sheet has a wound region, the filtration life can be further increased. This coarse filter fiber sheet may be in a state of being bonded to the auxiliary filtration nonwoven fabric or in a state of not being bonded. Examples of the combined state as in the former include, for example, a state in which at least a heat treatment (preferably heat treatment and pressure treatment) is bonded and integrated, a state in which an ultrasonic seal is integrated, a needle and a fluid flow (preferably a water flow) ) Intertwined and integrated, and adhesive and integrated with an adhesive. The coarse filtration fiber sheet may be any sheet having a larger average flow pore size (about 2 to 40 μm) than the auxiliary filtration nonwoven fabric (the auxiliary filtration nonwoven fabric having the largest average flow pore size when there are two or more types). Wet non-woven fabric manufactured to have a large average flow pore size in the same manner as filtration nonwoven fabric, Non-woven fabric in which melt blown fiber and thermoplastic stretched fiber are mixed to have a large average flow pore size in the same manner as auxiliary filtration non-woven fabric, It can be a melt blown nonwoven fabric manufactured to have a large average flow pore size, or a spunbond nonwoven fabric manufactured to have a large average flow pore size in the same manner as the filtration nonwoven fabric. Moreover, you may have the area | region where the main filtration nonwoven fabric and / or the auxiliary filtration nonwoven fabric were wound other than the area | region arrange | positioned in the state by which the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric were folded. Note that the fold-folding process can be performed by a fold-folding machine, and the peak height, the peak interval, and the like can be appropriately set depending on the intended use and desired physical properties.

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

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

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

Example 1
A nozzle piece having an orifice diameter of 0.3 mm and a pitch of 0.8 mm is heated to a temperature of 330 ° C., and polypropylene resin is discharged at a rate of 0.33 g / min per orifice. On the other hand, melt blown fibers formed by applying air at a temperature of 330 ° C. and a mass ratio of 240 times the amount of resin discharged are accumulated on a conveyor (distance between nozzle piece and conveyor: 49 cm). Manufactured. Next, the melt blown fiber web is passed between calender rolls (linear pressure: 0.5 kN / cm) set at a temperature of 80 ° C. composed of a metal roll and a resin roll, and a surface density of 80 g / m ² and a thickness of 0.15 mm. A melt blown nonwoven fabric (main filtration nonwoven fabric) having an apparent density of 0.53 g / cm ³ , an average fiber diameter of 1.7 μm, and an average flow pore diameter of 1.9 μm was produced. On the other hand, a nozzle piece having an orifice diameter of 0.2 mm and a pitch of 0.8 mm is heated to a temperature of 320 ° C., and a polypropylene resin is discharged at a rate of 0.06 g / min per orifice. A melt blow fiber 2 made of polypropylene having an average fiber diameter of 1.8 μm in the same direction as the direction of gravity is applied to the resin at a temperature of 330 ° C. and a mass ratio of 70 times the amount of resin discharged (melting point: 160 ° C) flow was formed. From the direction perpendicular to the flow of the melt blown fiber 2 made of polypropylene, the two opening cylinders 31 as shown in FIG. 2 are accommodated in the housing 32, and the core component is supplied from the opening machine 3 having the air nozzle 33. A core-sheath type thermoplastic stretched short fiber 4 having a fiber diameter of 21.6 μm and a fiber length of 38 mm, comprising a polypropylene resin (melting point: 160 ° C.) and having a sheath component made of a polyethylene resin (melting point: 135 ° C.), is supplied. Mixed with meltblown fiber 2 In addition, the mixing mass ratio of the polypropylene melt blown fiber 2 and the core-sheath type thermoplastic stretched short fiber 4 was (polypropylene meltblown fiber 2) :( core-sheath type thermoplastic stretched short fiber 4) = 65: 35. . A mixed fiber web was formed by collecting a fiber group in which the melt blown fiber 2 made of polypropylene and the core-sheath type thermoplastic short staple fiber 4 were mixed with a conveyor belt. The conveyor belt was made of a mesh body, and air was sucked from the side opposite to the belt collecting surface by a gas suction device to prevent disturbance of the fibers constituting the mixed fiber web. Next, this mixed fiber web was heat-treated for 3 minutes with a drier at a temperature of 145 ° C., and only the sheath component of the core-sheath thermoplastic stretched short fiber 4 was adhered, and the surface density was 50 g / m ² , the thickness. A mixed non-woven fabric (first auxiliary filtering non-woven fabric) having a 0.33 mm and an average flow pore size of 13.7 μm was produced. Next, in a state where the main filtration nonwoven fabric was sandwiched between the two first auxiliary filtration nonwoven fabrics, folding filtration was performed with a folding width of 14 mm by a folding machine to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Example 2)
As a sea-island fiber, a fiber produced by a composite spinning method in which 25 island components made of polypropylene are present in a sea component made of poly-L-lactic acid (hereinafter referred to as “PLLA”) (fineness: 1. 65 dtex, fiber length: 3 mm) was prepared. Next, this sea-island type fiber was immersed in an aqueous solution of sodium hydroxide at a temperature of 80 ° C. and 10 mass% for 30 minutes to extract and remove PLLA which is a sea component of the sea-island type fiber. .8 μm, standard deviation of fiber diameter distribution: 0.15, melting point: 172 ° C., cut to 3 mm fiber length, unfibrillated, stretched, having substantially the same diameter in the fiber axis direction ) On the other hand, as an adhesive fiber, a core-sheath type composite adhesive fiber (fiber diameter: 11) whose core component is made of polypropylene (melting point: 158 ° C.) and whose sheath component (adhesion component) is made of high-density polyethylene (melting point: 131 ° C.). .8 μm, fiber length cut to 10 mm, non-fibrillated, stretched). Next, the polypropylene microfiber and the core-sheath type composite adhesive fiber are dispersed in a dispersion bath made of water at a mass ratio of 50:50, made by a paper machine, dried at a temperature of 140 ° C., and simultaneously the core-sheath. Only the adhesive component of the type composite adhesive fiber is adhered, and a wet nonwoven fabric (second auxiliary filtration having a surface density of 38 g / m ² , a thickness of 0.34 mm, an apparent density of 0.11 g / cm ³ , and an average flow pore size of 12.1 μm) Nonwoven fabric) was produced. The fibers constituting this wet nonwoven fabric (second auxiliary filtration nonwoven fabric) were two-dimensionally arranged, and the maximum pore diameter was 1.7 times the average flow pore diameter. On the other hand, a main filtration nonwoven fabric produced in exactly the same manner as in Example 1 was prepared. Next, in a state where the main filtration nonwoven fabric was sandwiched between the two second auxiliary filtration nonwoven fabrics, folding filtration was performed with a folding width of 14 mm using a folding machine to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Comparative Example 1)
The same main filtration nonwoven fabric as Example 1 was prepared. On the other hand, a polypropylene net having an area density of 34 g / m ² , a thickness of 0.25 mm, an apparent density of 0.14 g / cm ³ , and a mesh size of 1 mm × 2 mm was prepared. Next, in a state where the main filtration nonwoven fabric was sandwiched between the two polypropylene nets, a folding filter was performed with a folding machine with a folding width of 14 mm to produce a laminated filter material. Next, the laminated filter material was arranged around the polypropylene porous cylinder so that the number of peaks was 100, and then both ends of the laminated filter material were fused by an ultrasonic welder. And the gasket was adhere | attached on the both end surfaces in the length direction of a porous cylinder, and the pleated type | mold cylindrical filter of inner diameter 30mm, outer diameter 69mm, and length 250mm was manufactured.

(Example 3)
A main filtration nonwoven fabric (60 cm length) produced in the same manner as in Example 1 and a mixed nonwoven fabric produced in the same manner as in Example 1 (first auxiliary filtration nonwoven fabric, 320 cm length) were prepared. Also, meltblown nonwoven fabric A (40 cm length) of the mean flow pore size 3μm surface density of 80 g / m ^2, melt-blown nonwoven fabric B (40 cm length) of the mean flow pore size of 5μm surface density of 80 g / m ^2, and a surface density of 80 g / Melt blown nonwoven fabrics C (40 cm long) each having an average flow pore size of 10 μm at m ² were prepared. Next, the main filtration nonwoven fabric is laminated on the mixed nonwoven fabric so that a position 120 cm from the left end of the mixed nonwoven fabric (first auxiliary filtration nonwoven fabric) and a left end of the main filtration nonwoven fabric coincide with each other. The melt blown nonwoven fabric A is laminated on the mixed nonwoven fabric so that the right end of the filtration nonwoven fabric and the left end of the melt blown nonwoven fabric A match, and then the right end of the melt blown nonwoven fabric A and the left end of the melt blown nonwoven fabric B match. The melt blown nonwoven fabric B is laminated on the mixed nonwoven fabric, and the melt blown nonwoven fabric C is laminated on the mixed nonwoven fabric so that the right end of the melt blown nonwoven fabric B and the left end of the melt blown nonwoven fabric C coincide with each other. Thus, a filter material laminate was manufactured. Next, the filter material laminate is wound in a flat shape from the left end so that the surface on which the main filtration nonwoven fabric of the filter material laminate is laminated is surrounded by a polypropylene perforated cylinder. A depth cylindrical filter having a diameter of 6.5 cm and a length of 25 cm was manufactured.

(Comparative Example 2)
In place of the first auxiliary filtration nonwoven fabric used in Example 3, the same polypropylene net as in Comparative Example 1 was used, except that the inner diameter was 3 cm, the outer diameter was 6.5 cm, and the length was the same as in Example 3. A 25 cm depth cylindrical filter was produced.

The performance of the cylindrical filters of Examples 1 to 3 and Comparative Examples 1 to 2 was examined as follows.
1. Water flow resistance The pressure loss when water was passed through each cylindrical filter at a flow rate of 25 L / min was determined as water flow resistance. The results are shown in Table 1.
2. Filtration efficiency JIS11 class dust dispersed in water with a 10ppm concentration test solution is uniformly stirred and water is passed through each cylindrical filter at a predetermined flow rate (25L / min for pleated type, depth type) 10 L / min), and the filtrate after 1 minute of water flow was collected. The number of particles for each particle size contained in this filtrate and the test solution before filtration was measured with a particle size distribution analyzer (Coulter Multisizer II, manufactured by Coulter, Inc.). Next, the filtration efficiency at each particle size was calculated from the following formula, and the particle size at which 100% filtration efficiency was obtained was defined as the filtration accuracy of the cylindrical filter. The results are shown in Table 1.
Filtration efficiency [%] = {(A−B) / A} × 100
A: Number of particles before filtration, B: Number of particles after filtration Filtration life JIS11 class dust dispersed in water with a predetermined concentration of test solution (20 ppm for pleated type, 10 ppm for depth type) is stirred uniformly and at a predetermined flow rate in each cylindrical filter. Water was passed through (25 L / min for the pleated type, 10 L / min for the depth type). The pressure loss is measured sequentially for each water flow rate, and the total water flow rate processed until the differential pressure from the initial pressure reaches a predetermined value (200 kPa for pleated type, 100 kPa for depth type) The filtration life was assumed. The results are shown in Table 1.

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

From Table 1, it was found that each of the pleated cylindrical filter and the depth cylindrical filter of the present invention has low water flow resistance and excellent filtration accuracy and filtration life. Moreover, the laminated filter material comprising the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric used in the cylindrical filter of the present invention can be processed (folded and wound) without damaging the main filtration nonwoven fabric. It was. From this result, it was found that the main filtration nonwoven fabric was not damaged during processing, from the result that the filtration life was long and the filtration performance was excellent without impairing the filtration accuracy in Table 1. Moreover, the laminated filter medium of the present invention was excellent in handling workability at the time of folding and winding.

Process drawing showing an example of a manufacturing process of the 1st auxiliary filtration nonwoven fabric Cross-sectional schematic diagram of an example of a spreader

Explanation of symbols

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

Claims (5)

A main filtration nonwoven fabric composed of a melt blown nonwoven fabric, and a wet nonwoven fabric having a mean flow pore size larger than that of the main filtration nonwoven fabric and not substantially fibrillated, and produced from fibers having a fiber diameter of less than 20 μm. Including an ultrafine fiber of 4 μm or less, and an auxiliary filtration nonwoven fabric made of a wet nonwoven fabric having a maximum pore size of 2 times or less of the average flow pore size, including a bonded fiber having a fiber diameter of 8 μm or more and less than 20 μm, A cylindrical filter, characterized in that a main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric are arranged adjacent to each other and are arranged around a porous cylinder. In the auxiliary filtration nonwoven, characterized in that the standard deviation of fiber diameter distribution of the ultrafine fibers, the value obtained by dividing the average value of the fiber diameter of the ultrafine fibers is 0.2 or less, according to claim 1 Cylindrical filter. The cylindrical shape according to claim 1 or 2 , wherein the main filtration nonwoven fabric and the auxiliary filtration nonwoven fabric have a region arranged in a wound state around a porous cylinder. filter. It has the area | region arrange | positioned in the state by which the said main filtration nonwoven fabric and the said auxiliary filtration nonwoven fabric were folded in the circumference | surroundings of a perforated pipe | tube, The one in any one of Claims 1-3 characterized by the above-mentioned. The cylindrical filter as described. The cylindrical filter according to any one of claims 1 to 4 , further comprising a region in which a coarse filtration fiber sheet having a larger average flow pore size than the auxiliary filtration nonwoven fabric is disposed.

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