JP5080041B2 - Air filter medium, streamer filter using the same, and method for producing air filter medium - Google Patents

Description

  The present invention relates to an air filter medium suitable for medium to high performance filters used for air conditioning in general buildings, factory air conditioning equipment, computer rooms and hospitals, and in particular, a plurality of bag-like filter media are fixed to a mounting frame. It is related with the filter medium for air filters used suitably for the pocket type filter or the blow-off type filter of this form, the blow-off type filter using the same, and the manufacturing method of the filter medium for air filters.

  As a medium- to high-performance filter used for air conditioning in general buildings, factory air conditioning equipment, computer rooms and hospitals, etc., a blow-off filter with a plurality of bag-like filter media fixed to a mounting frame is known. Yes. As such a filter, for example, in Patent Document 1, the opposing filter media walls of a bag-like filter are sewn with a plurality of rows of sewing threads leaving a swell margin in the bag inner space, and both ends of the swell margin of each sewing thread are secured. A windsock filter bonded to the filter media wall is described. And as a filter medium used for this filter, a glass fiber, a synthetic fiber, or a combination felt thereof is a main material, and a glass fiber, a synthetic fiber, or a combination nonwoven fabric thereof is integrally polymerized on the outer surface as a covering material. It is described that can be used. Further, practically, as such a filter medium, an adhesive or a particulate hot melt is formed by combining a mat made of ultrafine glass fibers and a nonwoven fabric formed by binding staple fibers having an average fiber diameter of 10 to 100 μm with an adhesive. A filter medium bonded with a resin is known.

  In this way, by using a thick filter medium containing ultrafine glass fibers as the filter medium for the air filter, the initial pressure loss is low, fine dust and coarse dust are collected, and the dust holding capacity is increased. Is possible.

  However, since the above-described practical filter medium has a laminated structure, a special bonding process for that purpose is required, which increases the manufacturing process and increases the cost. In addition, since inorganic fibers are used, there are problems such as being unable to recycle as a heat source and placing a burden on the environment, and since processing methods other than sewing cannot be adopted when processing into bags, further labor is required. There were a lot of cost-up factors, such as hanging.

  Accordingly, the present inventor considered using environmentally important filter media made of a 100% organic material described in Patent Document 2. Patent Document 2 discloses that an ultrafine fiber having an average fiber diameter of 0.1 to 10 μm manufactured by a melt blow method is 5 mass% or more and less than 50 mass%, and a heat fusible fiber having an average fiber diameter of 10 to 100 μm is 50 mass% or more and 95 mass%. % Or less, and the heat-fusible fiber is a non-woven fabric fused. However, in this filter medium, the filter medium is easily damaged when the bag-shaped filter medium is swelled by the inflow air, and the filter medium is rubbed and worn away during use, or the filter medium is flexible. There was a problem that the bag shape could not be maintained. In addition, when trying to make a laminated structure with another nonwoven fabric for reinforcement, there is a problem that a risk such as an increase in cost due to the above-described laminated structure occurs again.

JP 2001-9224 A Japanese Patent Laid-Open No. 11-226328

  The present invention solves the above-mentioned problems, and is a filter medium for an air filter suitable for a medium-to-high performance filter that has low initial pressure loss, can collect fine dust and coarse dust, and can increase dust holding capacity. The manufacturing process is small, the cost can be reduced, the burden on the environment is small, the recyclability is excellent, and when processing into a bag shape, fusion processing is possible in addition to sewing, and the labor involved in processing There is little problem of cost increase, and there is no problem that the filter medium is damaged when the bag-shaped filter medium swells due to inflowing air, or the bag-shaped filter medium rubs and wears out during use. It is an object of the present invention to provide a filter medium for air filter excellent in shape retention, a blow-off filter using the same, and a method for producing a filter medium for air filter.

In order to solve the above-mentioned problems, the invention according to claim 1 or 2 is an air filter medium comprising an ultrafine fiber layer and a long fiber layer, and the ultrafine fiber layer has an average fiber diameter produced by a melt blow method. The fiber length is 5 to 160 mm, and the average fiber diameter is 10 to 10 mm. The fiber length is composed of ultrafine fibers composed of 0.1 to 10 μm polyolefin resin , high melting point resin component composed of polypropylene resin , and low melting point resin component composed of polyethylene resin. Resin having a high melting point made of a polyester resin produced by a spunbond method, in which 100 μm heat-fusible short fibers are mixed and the heat-fusible short fibers are fused. A heat-fusible long fiber comprising a component and a low-melting resin component made of polyethylene resin is formed by fusing, and the heat-fusible long fiber forms the ultrafine fiber layer. The heat-fusible short fibers are heat-fused to the fibers constituting the long-fiber layer while the heat-fusible short fibers are heat-fused by fusing the polyethylene resin constituting the heat-fusible long fibers to the constituting fibers. The filter material for an air filter is characterized in that the ultrafine fiber layer and the long fiber layer are laminated and integrated by heat-sealing by fusing polyethylene resin that constitutes the material.

The invention according to claim 3-4, a windsock-shaped filter characterized by using a filter medium for an air filter according to claim 1 or 2.

In the invention which concerns on Claim 5 , it is a manufacturing method of the filter material for air filters which consists of an ultrafine fiber layer and a long fiber layer, Comprising: The ultrafine fiber which consists of polyolefin resin with an average fiber diameter of 0.1-10 micrometers is formed by the melt blow method Then, the heat-fusible short having a fiber length of 5 to 160 mm and an average fiber diameter of 10 to 100 μm comprising a high melting point resin component made of this ultrafine fiber and a polypropylene resin and a low melting point resin component made of a polyethylene resin. The fiber is mixed to form an ultrafine fiber web, and then the heat composed of the ultrafine fiber web and a high melting point resin component made of a polyester resin and a low melting point resin component made of a polyethylene resin manufactured by a spunbond method. Laminating a long-fiber nonwoven fabric formed by fusing long fusible fibers, and then fusing the heat- fusible short fibers of the ultrafine fiber web Forming the ultrafine fiber layer and thermally fusing the heat-fusible long fibers to the constituent fibers of the ultrafine fiber web by fusing the polyethylene resin constituting the heat-fusible long fibers, and at the same time, Laminating the ultrafine fiber layer and the long fiber nonwoven fabric by thermally fusing the heat fusible short fibers to the constituent fibers of the long fiber layer by fusing the polyethylene resin constituting the heat fusible short fibers. It is the manufacturing method of the filter medium for air filters characterized by integrating.

  According to the present invention, it is a filter medium for an air filter suitable for a medium / high performance filter that has low initial pressure loss, collects fine dust and coarse dust, and can increase dust holding capacity, and has a small manufacturing process. Cost can be reduced, environmental impact is low, recyclability is excellent, and fusion processing is possible in addition to sewing when processing into a bag shape. In addition, there is no problem that the filter medium is damaged when the bag-shaped filter medium swells due to inflowing air, or the bag-shaped filter medium rubs and wears out during use, and the shape of the filter medium is excellent. In addition, it is possible to provide a filter medium for air filter, a blow-off filter using the same, and a method for producing a filter medium for air filter.

  Hereinafter, preferred embodiments of a filter medium for an air filter according to the present invention, a streamer filter using the filter medium, and a method for producing a filter medium for an air filter will be described in detail. In addition, the manufacturing method of the filter medium for air filters of this invention is demonstrated in description of the filter medium for air filters.

  The filter medium for an air filter of the present invention comprises an ultrafine fiber layer and a long fiber layer, and the ultrafine fiber layer has an average fiber diameter of 0.1 produced by a melt blow method so that fine dust can be collected. It contains 10 μm ultrafine fibers.

  Although the conditions for producing ultrafine fibers by this melt blowing method are not particularly limited, for example, they can be produced under the following conditions. That is, a nozzle piece arranged with 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., and 0.02 to 1.5 g / min per orifice. The fiber is discharged at a rate of. An ultrafine fiber can be produced by applying air at a temperature of 220 to 400 ° C. and an amount of air that is 5 to 2,000 times the fiber discharge amount at a mass ratio.

  The ultrafine fibers thus produced have an average fiber diameter of 0.1 to 10 μm. If the average fiber diameter of the ultrafine fibers is less than 0.1, the pressure loss tends to increase, making it difficult to produce a filter medium for an air filter that can be used for a long time, while the average fiber diameter is 10 μm. Since it tends to be difficult to collect fine dust, the fine fiber having an average fiber diameter of 0.25 to 5 μm is preferable.

  In addition, the average fiber diameter in this invention means the average value of the fiber diameter in 200 fibers (for example, ultrafine fiber). This fiber diameter can be easily measured from, for example, an electron micrograph of a cut surface obtained by cutting an air filter medium in the thickness direction. When the cross-sectional shape of the fiber is non-circular, the diameter of a circle having the same area as the cross-sectional area of the fiber is regarded as the fiber diameter.

  Examples of the resin component constituting the ultrafine fiber produced by the melt-blowing method include one or more types such as polyolefin resins such as polypropylene and polyethylene, polyester resins, polyamide resins, polycarbonate resins, and urethane resins. Can be. Among these, it is preferable to include a polyolefin-based resin on the surface of the ultrafine fiber, and more preferable to include a polypropylene-based resin on the surface of the ultrafine fiber, which makes it easy to produce ultrafine fibers and easily electretize.

  The proportion of such ultrafine fibers in the ultrafine fiber layer is preferably 5% by mass or more and less than 50% by mass. If the amount of the ultrafine fiber is less than 5% by mass, the amount of the ultrafine fiber may be too small to collect the fine dust. Since it may clog, it is more preferable that it is 7-40 mass%, and it is further more preferable that it is 10-35 mass%.

  In addition to the ultrafine fibers as described above, the ultrafine fiber layer includes heat-fusible fibers having an average fiber diameter of 10 to 100 μm, and the heat-fusible fibers are fused. Therefore, a relatively rough space can be formed, coarse dust can be collected, and pressure loss can be reduced, so that it can be used for a long time.

  The average fiber diameter of this heat-fusible fiber needs to be 10 to 100 μm. If the average fiber diameter is less than 10 μm, a relatively rough space cannot be formed, resulting in a high pressure loss and a tendency that the fiber cannot be used for a long time. On the other hand, if the average fiber diameter exceeds 100 μm, the space formed by the heat-fusible fiber is too large, and even if ultrafine fibers are mixed, there is a tendency that fine dust cannot be collected. It is more preferable that it is 20-70 micrometers, and it is still more preferable that it is 20-55 micrometers.

  This heat-fusible fiber is made of, for example, a one-type all-melt type, such as a polyolefin resin such as polypropylene or polyethylene, a polyester resin, a polyamide resin, a polycarbonate resin, or a urethane resin, or two of these resins. It can be a composite type containing more than one type. Among these, the latter composite type can be preferably used because the fiber shape can be maintained by the resin component that is not fused and the space formed by the heat-fusible fiber is excellent.

  As this suitable composite-type heat-fusible fiber, for example, (1) a resin component having a high melting point is used as a core component, and a resin component having a lower melting point than this resin component having a high melting point is a sheath component (fusion component). (2) Side-by-side type in which a high melting point resin component and a resin component having a lower melting point than this high melting point resin component (fusion component) are bonded together ( 3) A sea-island type resin in which many low-melting point resin components are scattered in the low-melting point resin component (sea component and fusion component). Among these, a core-sheath type, an eccentric type, or a sea-island type heat-fusible fiber that can reduce the space by heat at the time of heat-sealing or hardly reduce the form stability can be suitably used.

  The melting point difference between the high melting point component and the low melting point component (fusing component) of the composite heat-fusible fiber is preferably 10 ° C. or higher and 20 ° C. or higher so that neither resin component is melted. Is more preferable. In addition, if the ultrafine fiber is also fused when the heat fusible fiber is fused, it becomes impossible to collect fine dust. Therefore, the low melting point component (fusion component) of the heat fusible fiber is It is preferably 10 ° C. or more lower than the melting point of the ultrafine fiber (when the ultrafine fiber is composed of a plurality of resin components, the resin component having the lowest melting point is used as a reference), more preferably 20 ° C. or more. For example, as described above, when the ultrafine fiber is made of a suitable polypropylene resin, the melting point of the fusion component of the heat-fusible fiber is preferably 150 ° C. or less, and more preferably 140 ° C. or less. In this case, the fusion component of the heat-fusible fiber is preferably made of a polyethylene resin.

  The heat-fusible fiber may be a long fiber or a short fiber, but is preferably a short fiber so that it can be present in a state of being uniformly mixed with the ultrafine fiber. 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 ultrafine fiber.

  Further, if the heat-fusible fiber is drawn, it is excellent in strength and rigidity, and can be suitably used because it can maintain a relatively rough space formed by the heat-fusible fiber. .

  The heat-fusible fiber occupies 50% by mass or more of the air filter medium and preferably contains ultrafine fibers, and preferably 95% by mass or less so that a relatively rough space can be formed. More preferably, it occupies 60-93 mass% of the filter medium for air filters, More preferably, it occupies 65-90 mass%.

  Further, the heat-fusible fiber does not need to be made of one type, and two or more types of heat-fusible fibers that are different in terms of fiber diameter, composition, fiber length, etc. can be mixed. . In addition, it is possible to form a more appropriate space by mixing two or more types of heat-fusible fibers having different fiber diameters, and there is a difference of about 10 to 50 μm in terms of average fiber diameter. It is preferable to mix two or more types of adhesive fibers.

  The ultrafine fiber layer is mainly composed of ultrafine fibers and heat-fusible fibers. Besides these fibers, nylon fibers, vinylon fibers, polyester fibers, acrylic fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers, etc. Synthetic fibers and functional fibers can be mixed to impart various properties.

  As this functional fiber, for example, vinylidene fiber, polyvinyl chloride fiber, polyclar fiber, or modified acrylic fiber is mixed to impart flame retardancy, or silver or copper is included to impart antibacterial properties. Fibers can be mixed. In addition, functional fibers having functions such as antistatic properties, deodorizing properties, deodorizing properties, and hygroscopic properties can be mixed. In addition, it is also possible to mix the functional substance which has these functions in the said ultrafine fiber and / or a heat-fusible fiber. In addition, if polyolefin fiber and acrylic fiber and / or modified acrylic fiber are mixed, it can be charged by friction.

  These ultrafine fibers and fibers other than the heat-fusible fibers (hereinafter referred to as “other fibers”) do not interfere with the collection of fine dust by the ultrafine fibers and the formation of a relatively coarse space by the heat-fusible fibers. Thus, it is preferable that it is 45 mass% or less of a microfiber layer. The other fibers may be long fibers or short fibers, but are preferably short fibers so that they can exist in a state of being uniformly mixed with ultrafine fibers or heat-fusible fibers. In the case of short fibers, the fiber length is preferably 5 to 160 mm, and more preferably 25 to 110 mm.

  Furthermore, it is preferable that the other fibers have a melting point higher by 10 ° C. or more than the melting point of the fusion component of the heat-fusible fiber so as not to be melted by heat when fusing the heat-fusible fiber. It is more preferable to have a melting point higher by at least ° C.

  The ultrafine fiber layer is mixed with the above-described fibers, preferably uniformly mixed, and the heat-fusible fibers are fused. Note that the ultrafine fiber layer can be composed only of the organic fibers as described above, and can be incinerated when the service life of the filter medium for the air filter comes to be suitable for disposal.

The thickness of the ultrafine fiber layer is preferably 1 to 30 mm. When the thickness of the ultrafine fiber layer is less than 1 mm, a relatively rough space cannot be formed by the heat-fusible fiber, so that there is a tendency that the pressure loss is high and it cannot be used for a long period of time. Even if the filter medium is dense or rough, there is a tendency that a portion not involved in filtration tends to increase, and when processing into a bag shape or the like, the processing tends to be difficult, so the thickness of 2 to 2 It is more preferably 20 mm, and further preferably 3 to 15 mm. In addition, this thickness means the value at the time of 1-g load per 1 cm < ² > unit area.

The surface density of the ultrafine fiber layer is preferably 50 to 450 g / m ² . If the areal density is less than 50 g / m ² , the density of the fibers tends to be too low and it becomes difficult to collect fine dust. On the other hand, if the area density exceeds 450 g / m ² , the density of the fibers tends to be low. too high, immediately clogged by coarse dust, because there is a tendency that can not be used for a long period of time, more preferably from 75~400g / m ^2, and even a 100~300g / m ² Further preferred.

Furthermore, the apparent density of the ultrafine fiber layer is preferably 0.001 to 0.1 g / cm ³ . If the apparent density is less than 0.001 g / cm ³ , it tends to be difficult to collect fine dust. On the other hand, if the apparent density exceeds 0.1 g / cm ³ , it is easily observed due to coarse dust. It is more preferably 0.01 to 0.05 g / cm ³ because clogging tends to occur and the product cannot be used for a long time.

  The filter medium for an air filter of the present invention is composed of the ultrafine fiber layer and the long fiber layer described above, and the long fiber layer is formed from a heat-fusible long fiber manufactured by a spunbond method, The ultrafine fiber layer and the long fiber layer are laminated and integrated by thermally fusing the heat-fusible long fibers to the fibers constituting the ultrafine fiber layer.

  When the long fiber layer is laminated and integrated, the strength of the entire filter medium for air filter is improved and the surface resistance is excellent. For example, when used as a bag-shaped filter medium, when the bag-shaped filter medium swells due to inflow air In addition, there is no risk that the filter medium is damaged or the bag-shaped filter medium rubs and wears out during use, and the shape of the filter medium is excellent. In addition, since it is laminated and integrated with heat-bonding fibers, there is no need to provide a new step for preparing an adhesive or hot-melt resin for lamination and a subsequent bonding step, and it can be simply heated. Since it can be manufactured by a process, there is an advantage that the manufacturing process is small and the cost can be reduced.

  Moreover, since it can consist only of organic substance, there is an advantage that it does not place a burden on the environment due to the disposal process like glass fiber, and is excellent in recyclability as a heat source. In addition, in the case of a material in which a glass fiber mat and a nonwoven fabric are bonded together, sewing is required when processing into a bag shape, but in the present invention, fusion processing is possible in addition to sewing, and a nonwoven fabric such as a separator is used. In the case of joining to the filter medium, joining is possible only by heat fusion, and there is an advantage that the labor required for processing is small and the cost can be reduced.

  Examples of the heat-fusible long fibers produced by the spunbond method for forming the long fiber layer include polyolefin resins such as polypropylene and polyethylene, polyester resins, polyamide resins, polycarbonate resins, and urethanes. It is preferably a composite type containing two or more types of resins such as a resin. By being a composite type, the fiber shape can be maintained by a resin component that is not fused, and the fibers constituting the long fiber layer are thermally fused to form a strong structure by heat-fusible long fibers. In addition, the fibers constituting the ultrafine fiber layer can be heat-sealed to form a structure in which the ultrafine fiber layer and the long fiber layer are laminated and integrated.

  As this suitable composite-type heat-fusible long fiber, for example, (1) a resin component having a high melting point is used as a core component, and a resin component having a lower melting point than the resin component having a high melting point is used as a sheath component (fusion component). ) Core-sheath type or eccentric type, and (2) side-by-side type in which a high melting point resin component and a low melting point resin component (fusion component) are bonded together, (3) A sea-island type resin in which many low melting point resin components are scattered in the low melting point resin component (sea component and fusion component). Among these, a core-sheath type, an eccentric type, or a side-by-side type heat-fusible long fiber having an excellent heat-sealing effect can be suitably used.

  The melting point difference between the high melting point component and the low melting point component (fusion component) of the composite heat-fusible long fiber is preferably 10 ° C. or more, and preferably 20 ° C. or more so as not to melt any resin component. Is more preferable. In addition, when the heat-fusible long fibers are fused to the constituent fibers of the ultra-fine fiber layer, if the ultra-fine fibers are also fused, fine dust cannot be collected. The low melting point component (fusion component) is preferably 10 ° C. or more lower than the melting point of the ultrafine fiber (when the ultrafine fiber is composed of a plurality of resin components, the resin component having the lowest melting point is used as a reference). Low is more preferable. For example, as described above, when the ultrafine fiber is made of a suitable polypropylene resin, the melting point of the fusion component of the heat-fusible long fiber is preferably 150 ° C. or less, and more preferably 140 ° C. or less. . In this case, the fusion component of the heat-fusible long fiber is preferably made of a polyethylene resin.

  The average fiber diameter of the heat-fusible long fibers is preferably 10 to 100 μm, and more preferably 20 to 50 μm. When the average fiber diameter is less than 10 μm, the pressure loss of the filter medium for the air filter increases, and there is a tendency that it cannot be used for a long period of time. On the other hand, when the average fiber diameter exceeds 100 μm, the rigidity becomes too high, May be inferior in workability or may be difficult to integrate with the ultrafine fiber layer. Moreover, this heat-fusible long fiber does not need to consist of one type, and it is also possible to mix two or more types of heat-fusible long fibers that differ in terms of fiber diameter, composition, fiber length, etc. It is.

The long fiber layer preferably has a thickness of 0.1 to 2 mm. If the thickness of the long fiber layer is less than 0.1 mm, the filter medium strength improvement effect, surface resistance improvement effect, and shape retention improvement effect may be insufficient. If the thickness exceeds 2 mm, Since the rigidity becomes too high and it may be difficult to process into a bag shape or the like, the thickness is more preferably 0.2 to 1.5 mm, and still more preferably 0.3 to 1 mm. In addition, this thickness means the value at the time of 1-g load per 1 cm < ² > unit area.

Moreover, it is preferable that the surface density of the said long fiber layer is 5-100 g / m < ² >. If the surface density is less than 50 g / m ^2, the strength improving effect of the filter medium, the surface resistance improving effect, and the like shape retention improving effect may become insufficient, while if it exceeds 100 g / m ^2, the stiffness too high, because there is a possibility that it becomes difficult to processed into a bag shape, more preferably from 7.5~80g / m ^2, and even more preferably 10 to 60 g / m ^2.

Moreover, it is preferable that the thickness of the filter medium for air filters of this invention is 1-30 mm. If the thickness is less than 1 mm, there is a risk that the space for holding the dust will not be sufficiently secured, so that it may not be used for a long time. If the thickness exceeds 30 mm, the air filter medium may be dense or rough. The portion that does not participate in the filtration tends to increase, and when processing into a bag shape or the like, the processing tends to be difficult. Therefore, the thickness is more preferably 2 to 20 mm, more preferably 3 to 15 mm. More preferably. In addition, this thickness means the value at the time of 1-g load per 1 cm < ² > unit area.

Moreover, it is preferable that the surface density of the filter medium for air filters is 50-500 g / m < ² >. If the surface density is less than 50 g / m ^2, since the space density of the fiber is too low to hold the dust is not sufficiently secured, there is a long period of time may not be used, on the other hand, if it exceeds 500 g / m ^2, the density of the fibers becomes too high, immediately clogged with coarse dust, because there is a long period of time tends to become unavailable, more preferably from ^{75~400g / m 2, 100~350g / m} 2 More preferably.

The apparent density of the air filter medium is preferably 0.001 to 0.1 g / cm ³ . If the apparent density is less than 0.001 g / cm ³ , it tends to be difficult to collect fine dust. On the other hand, if the apparent density exceeds 0.1 g / cm ³ , it is easily observed due to coarse dust. It is more preferably 0.01 to 0.05 g / cm ³ because clogging tends to occur and the product cannot be used for a long time.

  The filtration performance of the air filter medium of the present invention preferably functions as a medium / high performance filter. Specifically, in the test method defined in JIS B-9908 Type 1, the wind speed is 0.1 m / When atmospheric dust is supplied in seconds and evaluated by the counting method, the particle collection efficiency for particles of 0.3 to 0.5 μm is preferably 20 to 99%, and the particle collection efficiency is 30 to 99%. It is preferable that the particle collection efficiency is 35 to 99%. When the particle collection efficiency is less than 20%, the particle collection is insufficient, and when the particle collection efficiency exceeds 99%, the pore diameter of the filter medium for the air filter becomes too fine. There is a risk that the pressure loss before and after the filter medium will reach its limit and the service life will be shortened so that it cannot be used as a medium or high performance filter.

  The initial pressure loss of the air filter medium of the present invention is preferably 100 Pa or less, more preferably 75 Pa or less, and even more preferably 50 Pa or less when the test condition is a wind speed of 0.10 m / sec.

  In addition, the flame retardancy of the filter medium for air filter of the present invention is No. It is preferable to comply with Class 3 of 11A-2003 “Guidelines for test methods for filter media combustion for air purifiers”.

  The filter medium for an air filter of the present invention can be manufactured, for example, as follows. First, as shown in FIG. 1, the heat-fusible fiber 4 opened by the fiber spreader 3 with respect to the flow of the ultrafine fiber 2 discharged from the melt blow apparatus 1 under the above-described conditions (in some cases, other fibers) And the both are mixed, and the mixed fibers are collected by a collecting body 5 such as a conveyor to form an ultrafine fiber web 6. Next, the ultrafine fiber web 6 is laminated on the long fiber nonwoven fabric 7 formed from heat-bondable long fibers. Next, by heat-treating the laminate, the heat-fusible fibers 4 are fused to form an ultrafine fiber layer, and the heat-fusible long fibers are thermally fused to the fibers constituting the ultrafine fiber web 6. . Thus, the filter material 8 for air filters can be manufactured by laminating and integrating the ultrafine fiber layer and the long fiber nonwoven fabric 7.

  Examples of the spreader 3 that supplies the heat-fusible fiber 4 include a card machine and a garnet machine, but a spreader 3 that houses a plurality of spreader cylinders 31 as shown in FIG. The heat-fusible fibers 4 can collide with the flow of the ultrafine fibers 2 vigorously and can be mixed with the ultrafine fibers 2 evenly in the thickness direction of the ultrafiber webs 6. Can be used. In addition, the spreader 3 can evenly spread even a fiber having a fiber length of about 25 to 110 mm which is suitable in the present invention.

  Moreover, when supplying the heat-fusible fiber 4 with the fiber spreader 3, it is preferable to supply from the direction as perpendicular as possible with respect to the flow of the ultrafine fiber 2 so that it can mix with the ultrafine fiber 2 more uniformly. For example, when the flow of the ultrafine fiber 2 discharged from the melt blow apparatus 1 is formed in the horizontal direction, the heat-fusible fiber 4 may be naturally dropped and supplied from above the flow of the ultrafine fiber 2. Although the flow of the ultrafine fiber 2 discharged from the melt blow apparatus 1 is generally the same as the direction in which the gravity works, the heat-fusible fiber 4 supplied from the fiber opening machine 3 is generally in the direction in which the gravity works. It is preferable to supply from a perpendicular direction. In the fiber opening machine 3 of FIG. 2, the air nozzle 33 which can supply air is provided so that the heat-fusible fiber 4 can be supplied at such an angle.

  In addition, by adjusting the angle at which the heat-fusible fiber 4 is supplied to the ultrafine fiber 2, the abundance ratio of the heat-fusible fiber 4 in the thickness direction of the ultrafine fiber web 6 is changed to change the thickness direction. A dense structure can also be formed.

  The collector 5 for collecting the ultrafine fiber web 6 in which the ultrafine fiber 2 and the heat-fusible fiber 4 are mixed may be a roll or a net. The collection body 5 is preferably air-permeable so that the fiber web 6 is not disturbed or scattered by collision with the airflow to be conveyed, and is provided with a device capable of sucking and removing the airflow on the side opposite to the collection surface. Is preferred.

  In this production example, a long-fiber nonwoven fabric 7 formed from heat-fusible long fibers is used. The long fiber nonwoven fabric is preferably a nonwoven fabric formed by heat fusing long fibers with heat-fusible long fibers. That is, the long fibers do not necessarily need to be heat-sealed, and can be a non-heat-bonded long fiber web conveyed from a spunbond manufacturing apparatus. This is because long fibers can be heat-bonded by a subsequent heat treatment to form a long-fiber layer even if they are not heat-sealed. However, in consideration of ease of handling in the process, it is preferable that the nonwoven fabric is formed by heat-sealing long fibers.

  The heat treatment in the present invention is carried out at a temperature not lower than the melting point of the fusion component of the heat-fusible fiber 4 and lower than the melting point of the ultrafine fiber 2 (including other fibers in some cases) in a substantially non-pressurized state. It is preferable to process. By doing so, the ultrafine fiber 2 is not formed into a film, can exhibit its original collection performance, and the relatively coarse space formed by the heat-fusible fiber is not impaired, and pressure loss is reduced. Since it does not become high, the filter medium 8 for air filters which can be used for a long time can be manufactured. In addition, the bulky air filter medium 8 can be manufactured in which the fusion is not biased to the vicinity of the surface of the air filter medium 8 and the air filter medium 8 is firmly fused.

  Further, by this heat treatment, the heat-fusible long fibers contained in the long-fiber nonwoven fabric 7 are heat-fused to the fibers constituting the ultra-fine fiber web 6, and as a result, the ultra-fine fiber layer and the long-fiber nonwoven fabric 7 are laminated and integrated. Can be made. That is, a heat treatment step was originally required to form the ultrafine fiber layer. For this essential step, the ultrafine fiber layer 6 and the long fiber layer 6 can be formed by simply placing the ultrafine fiber web 6 on the long fiber nonwoven fabric 7. The fiber nonwoven fabric 7 can be laminated and integrated. Thus, according to this manufacturing method, there is an advantage that it is possible to omit the composite process of the ultrafine fiber layer and other materials, which has been necessary conventionally, and to greatly reduce the process cost.

  Examples of the heat treatment apparatus 10 capable of performing such heat treatment include a hot air circulation type dryer and a suction type air through dryer. For example, when the ultrafine fiber is made of a polypropylene resin and the fusion component of the heat-fusible fiber is made of a polyethylene resin, the fusion is preferably performed by setting the atmospheric temperature of the heat treatment apparatus 10 to 140 to 150 ° C.

  In order to adjust the thickness of the air filter medium after this heat treatment, it is passed between rolls or between flat plate presses at a temperature lower than the melting point of any fiber constituting the air filter medium 8. Is also possible. Moreover, in order to raise collection efficiency more, it is also possible to implement an electret process after a fusion process. In addition, when electret-ized, in order to further increase the efficiency, it is preferable to reduce the fiber oil agent of the heat-fusible fiber as much as possible by washing with water or hot water.

  Next, a preferred method of using the air filter medium of the present invention will be described. As illustrated in FIG. 3, a plurality of the air filter medium 8 formed in a bag shape are juxtaposed and fixed to the holding frame 9. As shown in FIG. 4, the airflow filter and a pocket filter in which the air filter medium 8 is folded in a zigzag shape and fixed to a holding frame 9.

  As the holding frame 9, for example, aluminum, aluminum alloy, stainless steel, or various resins can be used. In the filter shown in FIG. 3 or FIG. 4, the air filter media can be joined by heat sealing or sewing. Further, the air filter medium 8 can be fixed to the holding frame 9 by, for example, inserting a thermoplastic hot melt resin such as polyvinyl acetate between the holding frame 9 and the filter medium 8. .

  The filtration performance of the above-mentioned windsock type filter or pocket type filter preferably functions as a medium-high performance filter. Specifically, in the test method defined in JIS B-9908 Type 2, evaluation is performed by a colorimetric method. Then, when the test condition is a wind speed of 2.5 m / sec, the particle collection average efficiency is preferably 40 to 99%, the particle collection average efficiency is preferably 50 to 99%, and the particle collection average is More preferably, the efficiency is 60 to 99%. When the particle collection average efficiency is less than 40%, the particle collection is insufficient, and when the particle collection average efficiency exceeds 99%, the pore diameter of the filter medium for the air filter becomes too fine. There is a risk that the pressure loss before and after the filter will reach its limit and the service life will be shortened so that it cannot be used as a medium or high performance filter.

  The streamer filter 11 illustrated in FIG. 3 is provided with a separator 12, and, as shown in FIG. 5, between the filter medium piece 8a and the filter medium piece 8b constituting the bag-shaped filter medium 8 for air filter. The separator 12 is joined in a U-shaped cross section by sewing 13, heat sealing or ultrasonic fusion. As a result, the distance between the air filter media 8 is maintained, and the air filter media 8 does not swell too much when in use, so that no dead space is generated by contact with the adjacent air filter media 8. The bag shape of the filter medium 8 is maintained at a predetermined size.

  Moreover, as a form of the separator 12, as illustrated in FIG. 6, the separator 12 made of a concavo-convex sheet having a concavo-convex portion is disposed between the two filter medium pieces 8a and the filter medium piece 8b. It is also preferable that each concave portion or convex portion is joined to the inside of the two filter medium pieces.

  Further, the structure and material of the separator 12 are not particularly limited, and a woven fabric, a knitted fabric, a non-woven fabric, or the like can be applied. Specific examples of the material of the separator 12 include polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, polyamide fibers such as nylon 6 and nylon 66, polyolefin fibers such as polypropylene and polyethylene, and acrylic fibers such as polyacrylonitrile. Not only synthetic fibers such as fibers, polyvinyl alcohol fibers and synthetic pulp, but also semi-synthetic fibers such as rayon, natural fibers such as cotton and pulp fibers, etc., or a combination of a plurality of types of fibers may be applied. it can.

Also, the thickness of the separator 12 is not particularly limited, but the thickness is preferably 0.1 to 2 mm. If the thickness is less than 0.1 mm, it may be difficult to join the separator 12 to the filter medium 8 for air filter. If the thickness exceeds 2 mm, the rigidity becomes too high and it is processed into a bag shape or the like. Since it may become difficult, it is more preferable that it is 0.2-1.5 mm in thickness, and it is still more preferable that it is 0.3-1 mm. In addition, this thickness says the value at the time of 0.5g load per 1 cm < ² > unit area.

The surface density of the separator 12 is not particularly limited, but the surface density is preferably 5 to 100 g / m ² . If the areal density is less than 5 g / m ² , the function of maintaining the distance between the filter media 8 for the air filter may not sufficiently function. On the other hand, if it exceeds 100 g / m ² , the rigidity becomes too high, and the bag because there may become difficult to process, such as the Jo, more preferably from 7.5~80g / m ^2, and even more preferably 10 to 60 g / m ^2.

  The separator 12 preferably includes fibers made of the same synthetic resin as the fibers of the air filter medium 8. For example, when the fibers of the air filter medium 8 are made of polyolefin fibers, It is preferable that the separator 12 also contains polyolefin fiber. By including the same type of fiber, the separator is firmly bonded to the air filter medium by heat sealing or ultrasonic fusing, so that the shape of the bag-shaped air filter medium can be maintained firmly. There is. In this respect, the material of the separator 12 is more preferably the same material as the long fiber layer described above. That is, it is preferably a heat-fusible long fiber manufactured by a spunbond method.

  As described above, in order to join the air filter medium 8 and to arrange the separator, if the processing is performed by heat sealing or ultrasonic fusion, it is possible to reduce the labor of processing compared to the processing by sewing. In this respect, the air filter medium 8 of the present invention can be processed by heat sealing or ultrasonic fusion, and is a particularly preferable material for a blow-off filter or pocket filter.

  Examples of the present invention will be described below, but these are only suitable examples for facilitating the understanding of the present invention, and the present invention is not limited to the contents of these examples.

(Filtering performance test method for air filter media-Counting method)
In the test method specified in JIS B9908 format 1, atmospheric dust is supplied at a wind speed of 0.1 m / sec to determine the particle collection efficiency (%) for particles of 0.3 to 0.5 μm.
(Filtering performance test method for streamers or pocket filters-Colorimetric method)
In the test method stipulated in JIS B-9908 Type 2, the average efficiency of particle collection (%) is measured by a colorimetric method at a wind speed of 2.5 m / sec at the air inlet of a blow-off filter or pocket filter. Ask.

Example 1
A melt-blowing nozzle piece arranged with an orifice diameter of 0.2 mm and a pitch of 0.8 mm was heated to a temperature of 320 ° C., and polypropylene fibers were discharged at a rate of 0.04 g / min per orifice. An ultrafine fiber 2 having a fiber diameter of 1 to 2 [mu] m (average fiber diameter of 1.5 [mu] m) in the same direction as the direction in which gravity acts by applying air at a temperature of 340 [deg.] C. and a mass ratio of 75 times to the discharged polypropylene fiber. Formed a flow of.

  Next, two opening cylinders 31 as shown in FIG. 2 are accommodated in a housing 32 at a substantially right angle to the flow of the ultrafine fibers 2, and the core component is polypropylene from the opening machine 3 provided with an air nozzle 33. Supplying 100% by mass of stretched core-sheath fiber with 30 μm fiber diameter and 64 mm fiber length made of resin (melting point 160 ° C.) and sheath component made of polyethylene resin (melting point 135 ° C.) Mixed with Fiber 2. The mixed fibers were collected by a mesh conveyor to form an ultrafine fiber web 6. In addition, air was sucked and removed from the side opposite to the collecting surface of the conveyor to prevent the ultrafine fiber web 6 from being disturbed.

Next, a long-fiber nonwoven fabric 7 (surface density 50 g / m ² , thickness) manufactured by a spunbond method and heat-bonded long fibers (average fiber diameter 10 μm) whose core is made of polyester resin and whose sheath is made of polyethylene fibers. 0.15 mm) is prepared and laminated so that the ultrafine fiber web 6 is placed on the long fiber nonwoven fabric 7. Next, by passing this laminate through a dryer at a temperature of 140 ° C. for 3 minutes, only the sheath component (polyethylene component) of the core-sheath type heat-fusible fiber is fused, and the surface density is 175 g / m ² , the thickness. A filter medium 8 for air filter having a length of 5.5 mm and an apparent density of 0.032 g / cm ³ was produced. The air filter medium 8 contained 10 g / m ² (7% by mass) of the polypropylene extra fine fiber 2 and 135 g / m ² (93% by mass) of the core-sheath type heat-fusible fiber.

  It was 30 Pa when the pressure loss in the wind speed of 0.10 m / sec of the obtained filter material 8 for air filters was measured with the pressure loss measuring machine (type 1) prescribed | regulated to JISB9908. Moreover, it was confirmed by the filtration performance test that the collection efficiency of the counting method is 40%. Moreover, the flame retardancy of the air filter medium 8 is No. 1 from Japan Air Cleaners Association. It conformed to Class 3 of 11A-2003 “Guidelines for test methods for filter media combustion for air purifiers”.

(Example 2)
In the same manner as in Example 1, a flow of ultrafine fibers 2 was formed. Next, two opening cylinders 31 as shown in FIG. 2 are accommodated in a housing 32 at a substantially right angle to the flow of the ultrafine fibers 2, and the core component is polypropylene from the opening machine 3 provided with an air nozzle 33. Resin (melting point 160 ° C.), sheath component is polyethylene resin (melting point 135 ° C.), fiber diameter 30 μm, fiber length 64 mm stretched core-sheath type heat-fusible fiber 70% by mass, core component is polypropylene Polypropylene is supplied with 30% by mass of a core-sheath type heat-fusible fiber having a fiber diameter of 47 μm and a fiber length of 76 mm made of a resin (melting point 160 ° C.) and a sheath component made of polyethylene resin (melting point 135 ° C.) Mixed with extra fine fiber 2. The mixed fibers were collected by a mesh conveyor to form an ultrafine fiber web 6. In addition, air was sucked and removed from the side opposite to the collecting surface of the conveyor to prevent the ultrafine fiber web 6 from being disturbed.

Next, a long-fiber nonwoven fabric 7 (surface density 50 g / m ² , thickness) manufactured by a spunbond method and heat-bonded long fibers (average fiber diameter 10 μm) whose core is made of polyester resin and whose sheath is made of polyethylene fibers. 0.20 mm) is prepared and laminated so that the ultrafine fiber web 6 is placed on the long fiber nonwoven fabric 7. Next, by passing this laminate through a dryer at a temperature of 140 ° C. for 3 minutes, only the sheath component (polyethylene component) of the core-sheath type fusible fiber is fused, and the surface density is 280 g / m ² , the thickness. An air filter medium 8 having a thickness of 11.5 mm and an apparent density of 0.024 g / cm ³ was produced. The air filter medium 8 contained 50 g / m ² (22% by mass) of the polypropylene ultrafine fiber 2 and 180 g / m ² (78% by mass) of the core-sheath type heat-fusible fiber.

  It was 40 Pa when the pressure loss in the wind speed of 0.10 m / sec of the obtained filter material 8 for air filters was measured with the pressure loss measuring machine (type 1) prescribed | regulated to JISB9908. Moreover, it was confirmed by the filtration performance test that the collection efficiency of the counting method is 35%.

(Example 3)
Using the air filter medium 8 obtained in Example 1, a blown filter shown in FIG. 3 is manufactured so that a long fiber layer (long fiber nonwoven fabric) is disposed downstream of the air filter medium 8. did. This blown filter is a blower in which six air filter media 8 formed into a bag shape having a depth of 860 mm are juxtaposed and fixed to a synthetic resin holding frame 9 having an air inlet dimension of 595 mm × 595 mm. It is a shape filter. Further, when forming into a bag shape, as shown in FIG. 5, a separator 12 is sewn into a U-shaped cross section by sewing 13 between a filter medium piece 8a and a filter medium piece 8b constituting a bag-shaped air filter medium 8. Joined. As a result, the distance between the air filter media 8 is maintained, and the air filter media 8 does not swell too much when in use, so that no dead space is generated by contact with the adjacent air filter media 8. The bag shape of the filter medium 8 was kept at a predetermined size. In addition, the long fiber nonwoven fabric 7 used in Example 2 was used for the separator 12. The obtained stream-flow filter was confirmed by a filtration performance test to have a color collection average particle collection efficiency of 90%.

Example 4
Using the air filter medium 8 obtained in Example 1, a blown filter shown in FIG. 3 is manufactured so that a long fiber layer (long fiber nonwoven fabric) is disposed downstream of the air filter medium 8. did. This blown filter is a blower in which six air filter media 8 formed into a bag shape having a depth of 860 mm are juxtaposed and fixed to a synthetic resin holding frame 9 having an air inlet dimension of 595 mm × 595 mm. It is a shape filter. Further, in forming into a bag shape, as shown in FIG. 6, each concave portion or convex portion of the separator 12 is provided between the filter medium piece 8 a and the filter medium piece 8 b constituting the bag-shaped air filter medium 8. The separator 12 was provided in a zigzag shape so as to be joined to the inside of the two filter media pieces. This joining was performed by ultrasonic fusion. As a result, the distance between the air filter media 8 is maintained, and the air filter media 8 does not swell too much when in use, so that no dead space is generated by contact with the adjacent air filter media 8. The bag shape of the filter medium 8 was kept at a predetermined size. In addition, the long fiber nonwoven fabric 7 used in Example 2 was used for the separator 12. The obtained stream-flow filter was confirmed by a filtration performance test to have a color collection average particle collection efficiency of 90%.

It is process drawing which shows an example of the manufacturing process of the filter medium for air filters of this invention. It is a cross-sectional schematic diagram of an example of a fiber spreader. It is a figure which shows an example of the filter using the filter medium for air filters of this invention. It is a figure which shows another example of the filter using the filter medium for air filters of this invention. It is a schematic diagram explaining the attachment method of the separator of the filter of FIG. It is a schematic diagram explaining another attachment method of the separator of the filter of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melt blow apparatus 2 Extra-fine fiber 3 Opening machine 31 Opening cylinder 32 Housing 33 Air nozzle 4 Heat-fusible fiber 5 Collecting body 51 Suction device 6 Extra-fine fiber web 7 Long fiber nonwoven fabric 8 Filter material 9 for air filter 9 Holding frame 11 Blow-off filter 12 Separator 13 Sewing 14 Heat seal or ultrasonic fusion

Claims (5)

An air filter medium comprising an ultrafine fiber layer and a long fiber layer, wherein the ultrafine fiber layer comprises an ultrafine fiber made of a polyolefin resin having an average fiber diameter of 0.1 to 10 μm produced by a melt blow method, and a polypropylene resin. comprising an average fiber diameter fiber length of from a low melting point of the resin component and made of a high melting point of the resin component and the polyethylene resin are 5~160mm are mixed and the heat-fusible short fibers of 10 to 100 [mu] m, the thermal fusion The short fiber layer is formed by fusing, and the long fiber layer is formed by heat fusion comprising a high melting point resin component made of a polyester resin and a low melting point resin component made of a polyethylene resin, which are produced by a spunbond method. Polyethylene which is formed by fusing long fibers having a heat-bonding property, and the heat-fusible long fibers constituting the heat- fusible long fibers to the fibers constituting the ultrafine fiber layer. The heat-fusible short fibers are fused to the fibers constituting the long fiber layer by fusing the polyethylene resin constituting the heat-fusible short fibers. The air filter medium, wherein the ultrafine fiber layer and the long fiber layer are laminated and integrated. The flame retardant property of the filter material for air filter is Japan Air Cleaning Association No. The filter medium for an air filter according to claim 1, which conforms to Class 3 of 11A-2003 "Guidelines for test method for filter medium combustion for air purifier". An air-flow filter using the air filter medium according to claim 1 or 2 . The blown-off filter according to claim 3 , wherein a separator made of the same constituent fiber as the long fiber layer is joined to the filter material for air filter by fusion bonding. A method for producing a filter medium for an air filter comprising an ultrafine fiber layer and a long fiber layer, wherein ultrafine fibers comprising a polyolefin resin having an average fiber diameter of 0.1 to 10 μm are formed by a melt blow method, and then the ultrafine fibers and polypropylene the average fiber diameter fiber length of from a low melting point of the resin component consisting of high-melting resin component and a polyethylene resin composed of a resin is 5~160mm is a mix of a heat-fusible short fibers 10~100μm ultrafine fibers A web is formed, and then the ultra-fine fiber web and a heat- fusible long fiber composed of a high melting point resin component made of a polyester resin and a low melting point resin component made of a polyethylene resin produced by a spunbond method are fused. When the ultra-fine fiber layer is formed by laminating the long-fiber non-woven fabric formed by wearing , and then fusing the heat- fusible short fibers of the ultra-fine fiber web Both the heat-fusible long fibers are heat-fused to the constituent fibers of the ultrafine fiber web by fusing the polyethylene resin constituting the heat-fusible long fibers, and at the same time, the heat-fusible short fibers are The superfine fiber layer and the long fiber nonwoven fabric are laminated and integrated by thermally fusing the constituent fibers of the long fiber layer by fusing the polyethylene resin constituting the heat-fusible short fibers. The manufacturing method of the filter material for an air filter to perform.

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