JP2009279554A - Laminated filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter capable of simultaneously increasing the gas permeability and collection efficiency of an object. <P>SOLUTION: A laminated filter 10 has a collection layer 11 and a space forming layer 12. The filter 10 is used so as to allow the layer 12 to be positioned downstream a fluid insufflation. A filling factor that is the percentage of a volume of the constitution material in the layer 12 occupied in an apparent volume of the layer 12 is 1 to 7 percent under the load of 0.3 kPa and its thickness is 1 to 12 mm under the same load, and the layer 11 is formed of nonwoven fabric with fiber diameter of 7 to 35 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer filter used by being attached to a filter attachment member such as a grease filter.

  The intake port of the range hood is referred to as a grease filter that collects the smoke exhaust fan and the like so as not to be directly contaminated by oil smoke or dust generated during cooking (hereinafter referred to as oil smoke). A metal filter is attached. However, this grease filter is insufficient in the collection of oil smoke and the like, and stains the inside of the hood and is cumbersome to clean. Therefore, in order to reduce the labor, it is further made of a material such as a nonwoven fabric on the outside. A disposable oil collecting filter is attached and used. As a method for increasing the collection rate of oil smoke and the like by such an oil collection filter, there is a method of narrowing the eyes of the filter by reducing the fiber diameter of the fiber to be used or increasing the amount of fiber to be used. It is done. However, if the filter is made finer in this way to increase the collection rate, the pressure loss when passing through the filter increases and the air permeability decreases. This leads to a reduction in ventilation performance by hindering suction of the ventilation fan by mounting the filter. Thus, the wind speed and the collection rate are in a trade-off relationship. Therefore, there is a need for a technique that does not decrease the wind speed even if the filter is made finer.

Apart from the above technique, Patent Document 1 discloses an ultrafine nonwoven fabric having an average fiber diameter of 0.5 to 6.0 μm and a bulk density of 0.05 to 0.50 g / cm ³ , an average fiber diameter of 10 to 60 μm, and a bulk. A filter is described in which a fiber sheet having a density of 0.05 to 0.50 g / cm ³ is laminated and formed into an uneven shape having a height of 3 to 100 mm. This filter is used in air cleaners, vacuum cleaners, automobiles, masks, and the like, and is intended to maintain the collection of fine particles over a long period of time. However, there is no disclosure regarding a technique that does not reduce the wind speed even if the filter is made finer.

  Similarly to Patent Document 1, a filter obtained by laminating an ultrafine fiber nonwoven fabric and another nonwoven fabric and processing the whole asperity is also described in Patent Document 2. In this filter, an ultrafine fiber nonwoven fabric is used as a filtration layer, and the other nonwoven fabric is used as a support layer. As this nonwoven fabric, a spunbond nonwoven fabric is used. However, this patent document also does not disclose a technique that does not decrease the wind speed even if the filter is narrowed.

  In addition to these documents, as a filter in which two or more layers of nonwoven fabric are laminated, the nonwoven fabric disposed on the suction side (outside) is dense, and the nonwoven fabric disposed on the fan side (inside) is rough Although the thing of patent document 3 and 4 is also known, there is no disclosure regarding the technique which does not reduce a wind speed even if it makes a fine filter eye.

JP-A-4-180808 JP 2000-271416 A JP-A-8-24535 JP 2000-218113 A

  The objective of this invention is providing the filter which can eliminate the fault which the prior art mentioned above has.

The present invention is a multilayer filter having a collection layer and a space forming layer,
The multilayer filter is used so that the space forming layer is located on the downstream side of fluid suction,
The space forming layer has a filling rate of 1 to 7%, which is a ratio (%) of the volume of the constituent material of the space forming layer in the apparent volume of the space forming layer under a load of 0.3 kPa. And the thickness under the same load is 1-12 mm,
The collection layer provides a multilayer filter made of a nonwoven fabric having a fiber diameter of 7 to 35 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the air permeability of the filter and the collection rate of the target object which were conventionally considered to be in a trade-off relationship can be improved simultaneously.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 is an exploded perspective view of an embodiment of the multilayer filter of the present invention. The multilayer filter 10 of the present embodiment includes a collection layer 11 and a space forming layer 12. The collection layer 11 and the space forming layer 12 are joined and integrated or laminated in a non-joined state. When the collection layer 11 and the space forming layer 12 are joined and integrated, as a joining method of the two, depending on the constituent material of these layers, adhesion by an adhesive or fusion by the action of heat, Known joining means such as fusion by sound waves are employed.

  As shown in FIG. 2, the multilayer filter 1 is used by being attached to a filter attachment member 20 having a shielding portion 21 on the attachment member. Examples of the filter attachment member 20 include a grease filter installed in a range hood, a lattice-like or other shape attachment member provided in an air conditioner, an exhaust duct, or the like. The shielding part 21 in the filter attachment member 20 is a part for supporting the filter in the filter attachment member 20. Since this part shields the passage of fluid, it is called a shielding part 21 in the present invention. For example, when the filter mounting member 20 is a grease filter, the grease filter is roughly classified into a baffle type and a mesh type, and the baffle plate of the baffle type grease filter corresponds to the above-described shielding portion. In the case of the mesh type, the metal part of the punching metal or the expanded metal corresponds to the shielding part. The shielding part in the attachment member provided in an air conditioner, an exhaust duct, or the like refers to, for example, a lattice-like part that supports a filter.

  The collection layer 11 in the multilayer filter 10 is a layer mainly having a function of collecting substances contained in the fluid to be sucked. On the other hand, the space formation layer 12 is a layer mainly having a function of forming a space between the collection layer 11 and the filter attachment member 20 in a state where the multilayer filter 10 is attached to the filter attachment member 20 and used. . The multilayer filter 10 is used by being arranged so that the space forming layer 132 is located on the downstream side of fluid suction.

  The multilayer filter 10 of this embodiment has one of the features of the space forming layer 12 that is bulky and has a high space forming ability. Specifically, as shown in FIG. 3A, in the conventional filter 100, when this is attached to the attachment member 20 having the shielding part 21, the part of the filter 100 that does not face the shielding part 21. In FIG. 3, the flow path of the fluid is short, so that the resistance when passing through the mounting member 20 is small (indicated by A in the figure). However, in the part facing the shielding part 21, the fluid passes by the shielding part 21. Is blocked, and fluid cannot pass unless it reaches a part where the shielding part 21 is not present (indicated by B in the figure). As a result, the flow path of the fluid becomes long, resulting in an increase in passage resistance. For this reason, it is not easy for the conventional filter 100 to ensure a sufficient fluid velocity to collect the target object. On the other hand, as shown in FIG. 3B, in the multilayer filter 10 of this embodiment, when this is attached to the attachment member 20 having the shielding portion 21, the trapping layer 11 and the attachment member 20 are shielded. A space S caused by the space forming layer 12 is formed between the portion 21 and the portion 21. Due to the presence of the space S, the fluid can easily pass through the mounting member 20 by shortcutting the space S even in a portion of the multilayer filter 10 facing the shielding portion 21. As a result, the flow path length of the fluid can be made shorter than that shown in FIG. 3A (indicated by B ′ in FIG. 3B), so that an increase in passage resistance can be prevented. For this reason, according to the multilayer filter 10 of the present embodiment, it is possible to ensure a sufficient fluid velocity to collect the target object even if the collection layer 11 is made finer. For this reason, the space forming layer 13 preferably has a sparse structure with a lower filling rate and higher air permeability than the trapping layer 11. That is, the multilayer filter 10 of the present embodiment is a filter having a layer structure in which the upstream side of fluid suction is dense (that is, the fiber density is high) and the downstream side (filter attachment portion side) is sparse (that is, the fiber density is low). Is preferred.

  The space forming ability of the space forming layer 12 in this embodiment is represented by a filling rate. The filling rate is the ratio (%) of the volume of the constituent material of the space forming layer 12 in the apparent volume of the space forming layer 12. It is determined that the smaller the value of the filling rate, the higher the space forming ability of the space forming layer 12.

  Depending on the material of the space forming layer 12, the space forming layer 12 may be compressed in the thickness direction by a suction force when the fluid is filtered, and the filling rate may increase. This has a negative effect from the viewpoint of ensuring a sufficient fluid velocity. Therefore, the space forming layer 12 needs to be able to secure a sufficient space even if a suction force acts on it. From this point of view, in this embodiment, the filling rate of the space forming layer 12 is evaluated under a load of 0.3 kPa. If the filling rate under this load is 1 to 7%, preferably 1 to 3%, it is possible to sufficiently prevent a decrease in fluid speed even in a state where a suction force is applied in actual use of the multilayer filter 10. It becomes.

  As is clear from the description regarding FIGS. 3A and 3B described above, the space forming layer 12 has a low filling rate, and if the space S itself is not sufficiently secured, the fluid speed is reduced. It cannot be prevented sufficiently. As a result of the study by the present inventors, the thickness of the space forming layer 12 under a load of 0.3 kPa is set to 1 to 12 mm, preferably 1.3 to 5 mm, so that the above-described fluid flow path length is sufficiently obtained. It turns out that it can be shortened. When the thickness of the space forming layer 12 under a load of 0.3 kPa is less than 1 mm, the flow path length of the fluid cannot be sufficiently shortened even if the porosity of the space forming layer 12 is set within the above range. The thickness of the space forming layer 12 varies depending on the shape of the shielding portion of the mounting member on which the multilayer filter 10 is mounted, but the fluid velocity reaches the upper limit at about 5 mm. Increasing the thickness further does not negatively affect the speed of the fluid, but it is impractical to give the thickness more than necessary, and the thickness of the multilayer filter 10 becomes unnecessarily large, so the upper limit is 12 mm. It was.

The filling rate and thickness of the space forming layer 12 under a load of 0.3 kPa are measured by the following method [method for measuring thickness].
In a state where a load of 0.3 kPa is applied to the multilayer filter 10, the side surface of the multilayer filter 10 is observed using a microscope. The thickness of the space forming layer 12 is visually measured at 10 points, and a value obtained by averaging them is defined as the thickness of the space forming layer 12.
[Measurement method of filling rate]
Calculate using the following formula.
Filling rate (%) = {basis weight of space forming layer (g / m ² )} × 100 / {density of constituent fibers (g / m ³ ) × space forming layer thickness (m)}
Here, the basis weight is the sheet weight of the space forming layer 12 per unit area. The thickness is measured by the above-described [Method for measuring thickness].

  The space forming layer 12 has a function for forming a space between the collection layer 11 and the filter attachment member 20 as described above. In addition to this function, the space forming layer 12 serves as a support for the collection layer 11. It is preferable that it also has a function from the viewpoint of easy handling of the multilayer filter 10. From this viewpoint, it is preferable that the space forming layer 12 has a property that is difficult to be deformed when an external force is applied. As a result of investigations by the present inventors on such properties, it has been found that it is advantageous that the space forming layer 12 has a high breaking strength. It has also been found that the space forming layer 12 is advantageously low in elongation. Specifically, regarding the breaking strength of the space forming layer 12, this value is preferably 1 to 150 N / 25 mm, and particularly preferably 3 to 100 N / 25 mm. Regarding the elongation, the elongation when a tensile stress of 0.5 N / 25 mm is applied is preferably 1 to 15%, particularly preferably 1 to 8%. The breaking elongation strength and elongation preferably satisfy the above range in either the machine direction (MD) or the width direction (CD) of the space forming layer 12 and satisfy the above range in both directions. Is more preferable. MD is a flow direction at the time of manufacturing the space forming layer 12. CD is a direction orthogonal to MD.

The breaking strength and elongation of the space forming layer 12 are measured by the following method.
[Measurement method of breaking strength]
The space forming layer 12 is peeled from the multilayer filter 10, and a rectangular measurement piece having a size of 100 mm on the MD and 25 mm on the CD which is a direction orthogonal to the MD is cut out. The cut out rectangular measurement piece is used as a measurement sample. The measurement sample is attached to a chuck of a tensile tester so that the MD is in the tensile direction. The distance between chucks is 50 mm. The measurement sample is pulled at 300 mm / min, and the maximum load point until the sample breaks is defined as the breaking strength of MD. Further, the space forming layer 12 is peeled from the multilayer filter 10, and a rectangular measurement piece having a size of 100 mm for CD and 25 mm for MD is cut out, and this is used as a measurement sample. The measurement sample is attached to a chuck of a tensile tester so that the CD direction is the tensile direction. The breaking strength of the CD is obtained by the same procedure as the above-described method for measuring the breaking strength of MD.
[Measurement of elongation]
With respect to MD and CD, a measurement sample is prepared in the same procedure as described above [Measurement method of breaking strength], and the measurement sample is attached to a chuck of a tensile tester and pulled. The conditions at this time are also the same as the above-mentioned [Measurement method of breaking strength]. The length of the stretched measurement sample when the load value is 0.5 N is measured, and the elongation at a load of 0.5 N / 25 mm is obtained from the following formula.
Elongation (%) = {(Length when stretched−50) / 50} × 100

  The space forming layer 12 has a sufficiently high air velocity when the air permeability measured by itself is 400 to 1000 m / (kPa · s), particularly 500 to 1000 m / (kPa · s). It is preferable from the point of obtaining. The air permeability of the space forming layer 12 is measured by KES-F8-AP1 (Breathability Tester) manufactured by Kato Tech. The air permeability of the space forming layer 12 can be controlled by adjusting the basis weight and thickness of the space forming layer 12 or the fiber diameter of the constituent fibers when the space forming layer 12 is made of a fiber material. Specifically, the greater the fiber diameter, the lower the basis weight, and the higher the thickness, the better the air permeability.

  The space forming layer 12 is preferably made of a material capable of forming a bulky space. From this viewpoint, the space forming layer 12 is preferably composed of a fiber sheet and a porous body such as a foam. When the space forming layer 12 is composed of a fiber sheet, a nonwoven fabric, a woven fabric, a knitted fabric, a net material, or a composite material thereof can be used as the fiber sheet. Since the multilayer filter 10 is generally used up, it is preferable to use a non-woven fabric as the fiber sheet in consideration of economy.

  A non-woven fabric can be obtained with a coarse or clogged eye depending on the production method. Moreover, a thing with high intensity | strength and a low thing are obtained. In consideration of the above-described various characteristics required for the space forming layer 12, when using a nonwoven fabric as the fiber sheet, it is preferable to use a spunbond nonwoven fabric which is a nonwoven fabric having a coarse mesh and high strength.

When using a nonwoven fabric as a fiber sheet, it is preferable that the basic weight is 10-50 g / m < ² >, especially 10-30 g / m < ² > from the point which raises the air permeability of the space formation layer 12 fully.

  Moreover, when using a nonwoven fabric as a fiber sheet, it is also preferable to use what gave the three-dimensional secondary process as this nonwoven fabric. This makes it possible to easily achieve the above-described filling rate. An example of the three-dimensional secondary processing is steel match embossing, which is a process of forming irregularities on a nonwoven fabric under heating or non-heating between a pair of embossing rolls that are meshed with each other. Moreover, the three-dimensional shaping method which shapes the unevenness | corrugation of the shape corresponding to this uneven | corrugated shaping | molding member by spraying high-pressure fluids, such as a high-pressure water stream, on the nonwoven fabric mounted on the uneven | corrugated shaping | molding member can also be used. Further, a three-dimensional shaping method using the apparatus shown in FIGS. 2 to 5 of Japanese Patent Application Laid-Open No. 2004-174234 related to the earlier application of the present applicant can be used.

  The fiber sheet that is particularly preferably used as the space forming layer 12 is one in which a spunbond nonwoven fabric is three-dimensionally formed by steel match embossing, or a net material is three-dimensionally formed by steel match embossing. These sheets have the characteristics that the constituent fibers are coarse and the filling rate is low. Further, this sheet is characterized by high breaking strength and low elongation.

  In the case where a porous body such as a foam is used as the space forming layer 12, a polyurethane foam may be used as the porous body. Such a foam also has the characteristics that the constituent fibers are rough and the filling rate is low. Moreover, it has the characteristics that breaking strength is high and elongation is low. Specific examples of such foams include Bridgestone's Everlite (registered trademark) SF · HR-08 and SF · HR-13, which are polyurethane foams having a three-dimensional skeleton structure. .

  As described above, the space forming layer 12 mainly has a function of forming a space between the collection layer 11 and the filter attachment member 20, and is used for oil collection used by attaching the laminated filter 10 to a range hood, for example. When used as a filter, it also has a function of preventing contamination of the grease filter that is the filter mounting member 20. The reason for this is that when oil smoke or the like collected in the collection layer 11 moves in the thickness direction of the laminated filter 10, it is difficult to reach the grease filter by being blocked by the space forming layer 11 that is bulky and has a weak capillary force. It is. From this viewpoint, the multilayer filter 10 of the present embodiment is particularly suitable as an oil collecting filter for a range hood.

  As the collection layer 11, it is preferable to use a collection layer that does not deteriorate the fluid permeability and has a fineness enough to collect the target object. From this viewpoint, the collection layer 11 is composed of a fiber sheet having a fiber diameter of 7 to 35 μm, preferably 10 to 25 μm. As such a fiber sheet, it is preferable to use a nonwoven fabric.

  When a nonwoven fabric is used as the collection layer 11, a spunlace nonwoven fabric, a spunbond nonwoven fabric, an air-through nonwoven fabric, an airlaid nonwoven fabric, a resin bond nonwoven fabric, a needle punched nonwoven fabric, or the like is used as the nonwoven fabric depending on the specific use of the laminated filter. Can do.

The collection layer 11 made of a nonwoven fabric preferably has a basis weight of 20 to 150 g / m ² , particularly 20 to 100 g / m ² . The thickness (under a 0.3 kPa load) is preferably 0.5 to 10 mm, particularly 1 to 5 mm. Further, the trapping layer 11 has an air permeability of 25 to 400 m / (kPa · s), particularly 40 to 400 m / (kPa · s), and sufficiently secures the wind speed of the exhaust fan and the range hood. At the same time, it is preferable for securing the collection property and antifouling property. The air permeability of the collection layer 11 is measured by KES-F8-AP1 (breathability tester) manufactured by Kato Tech. The air permeability of the collection layer 11 can be controlled by adjusting the basis weight and thickness thereof, or when the collection layer 11 is made of a fiber material, the fiber diameter of the constituent fibers. Specifically, the greater the fiber diameter, the lower the basis weight, and the higher the thickness, the better the air permeability. However, these work in reverse from the standpoint of collection. That is, the greater the fiber diameter, the lower the basis weight, and the higher the thickness, the lower the collection rate. For this reason, if the air permeability is too high, the trapping property is conversely lowered, and therefore, the upper limit of the air permeability is set to 400 m / (kPa · s).

  In particular, the collection layer 11 is preferably excellent in shape retention and can be used for a long period of time. From this point of view, as shown in FIGS. 4 and 5, the collection layer 11 has fiber assemblies 11b and 11c on both sides of the support 11a, and the fibers constituting the fiber assemblies 11b and 11c are formed. It is preferable that the fibers are entangled with each other and that an integral entangled state using the support 11a as a skeleton is formed. In the collection layer 11 shown in these drawings, the support 11a exists in the thickness direction of the collection layer 11, and the upper and lower surfaces of the support 11a are covered with the fiber assemblies 11b and 11c. Yes.

  The support 11a is a net made of a net-like material (a material having a mesh) such as a perforated film. In the present embodiment, the support 11a has a biaxial lattice shape. However, the support 11a is not limited to this and may be a triaxial or non-net, for example, a non-woven fabric. In other words, the type of support is not particularly limited as long as it is a carrier that has a constant hole and integrates the fiber web forming the fiber assembly in an entangled state. For example, a woven fabric having a relatively large mesh space such as a gauze-like woven fabric, or a fiber gap that can be integrated in an entangled state by superimposing fiber assemblies 11b and 11c on one or both sides. A nonwoven fabric or the like is also used as the support 11a.

The thickness of the support 11a is preferably 5 to 1000 times, more preferably 10 to 300 times, and still more preferably 15 to 50 times the diameter of the fibers constituting the fiber assemblies 11b and 11c. By setting the thickness within this range, the collection layer 11 is provided with a strength that does not cause sagging or the like. The wire diameter of the support 11a is preferably 20 to 1,000 μm, more preferably 100 to 300 μm. The wire diameter of the support 11a may be partially different. In this case, the wire diameter of the thick portion corresponds to the above value. This wire diameter corresponds to the thickness of the support 11a. The distance between the supports 11a is preferably 5 to 20 mm, and more preferably 8 to 15 mm. The basis weight of the support 11a is, 0.1~100g / m ^2, it is particularly preferably 1 to 30 g / m ^2.

On the other hand, the basis weights of the fiber assemblies 11b and 11c are preferably 20 to 150 g / m ² , respectively, from the viewpoint of ensuring the collection rate and form retention of the collection layer 11. In this case, the basis weights of the fiber assemblies 11b and 11c may be the same or different.

  The collection layer 11 shown in FIG. 4 is made by laminating fiber webs that are the basis of the fiber assemblies 11b and 11c on each surface of the support 11a, and in this state, a high-pressure water stream is jetted toward the fiber webs. The fibers of the fiber web on one side of the support 11a and the fibers of the fiber web on the other side, and the fibers of the fiber web and the support 11a are entangled and integrated, and at the same time, each fiber web is entangled by nonwoven fabric. It is manufactured by fixing to a support 11a as a fiber assembly. That is, the collection layer 11 is a spunlace nonwoven fabric in a broad sense.

  Instead of the collection layer 11 shown in FIG. 4, it is also preferable to use an air-through nonwoven fabric as the collection layer 11. This is because the air-through nonwoven fabric can form a bulky structure and can reduce pressure loss. Although it is bulky, the air-through nonwoven fabric generally has a property of low breaking strength. However, since the space forming layer 12 used together with the collection layer 11 serves as a support for the collection layer 11, the collection layer 11 is special. Even if a simple support is not included, sufficient strength can be maintained as the entire multilayer filter.

  When using a spunbonded nonwoven fabric that has been subjected to unevenness processing as the space forming layer 12, it is desirable that each surface of the collection layer 11 be planar. That is, it is desirable that each surface of the collection layer 11 has no irregularities. This is because each surface of the collection layer 11 is planar, so that the space formed by the uneven spunbond nonwoven fabric can be fully utilized. Further, when the surface of the collection layer 11 is planar, it is easier to process the production of the collection layer 11 and it is easy to handle, so that it can be easily combined with the space forming layer 12. Further, if each surface of the collection layer 11 is planar, the collection layer 11 does not need to be post-processed, so that the air permeability is not reduced due to the thickness reduction caused by the post-process, and the cost is reduced. This is also advantageous.

  For example, when the multilayer filter 10 is used as an oil collecting filter used by being attached to a range hood, the first layer facing outward and the second layer facing the space forming layer 12 are used as the collecting layer 11. It is preferable to use a material having a layer and the surface of the constituent fibers of the second layer having oil repellency, because the oil droplets can be effectively prevented from falling through. In addition, it is preferable to apply oil repellency to the space forming layer 12 or to use a constituent fiber having oil repellency because the oil droplets can be effectively prevented from falling through. The reason for this is as follows.

  FIG. 6 schematically shows a longitudinal section of the collection layer 11 having the above-described configuration. In the trapping layer 11, the surface of the fiber F1 existing in a substantially half surface region on one side in the thickness direction has oil repellency, and the surface of the fiber F2 existing in the remaining substantially half surface region has oil repellency. Not done. When this collection layer 11 is used with the side where the fiber F2 exists positioned on the range side (side facing outward), as shown in the figure, the oil component A is first applied to the fiber F2 positioned on the range side. Adhere to. Since the fiber F2 does not have oil repellency, the oil component A adhering to the fiber F2 spreads on the surface of the fiber F2 and forms an oil film M. The oil component A constituting the oil film M moves in the thickness direction of the collection layer 11 toward the fan side by capillary action. When the oil component M that moves toward the fan reaches the region where the fiber F1 exists, the oil repellency of the fiber F1 prevents the formation of the oil film M, and also prevents the transfer due to capillary action. As a result, it comes to exist in the state of oil droplets on the surface of the fiber F1, and it becomes difficult for the capillary force to act. As a result, the oil component A is difficult to move to the fan side of the collection layer 11. For this reason, the oil component A can be prevented from falling through. If the surface of the constituent fiber of the space forming layer 12 is made oil repellent in addition to the trapping layer 11, the back-through of the oil component A is more effectively prevented by the same mechanism. Further, even if the surface of the constituent fiber of the collection layer 11 is not oil-repellent, if the surface of the constituent fiber of the space forming layer 12 is oil-repellent, it is possible to prevent the oil component A from falling through by the same mechanism. it can.

  In order to make the surface of the fiber have oil repellency, (i) a non-woven fabric is prepared using a fiber that does not have an oil repellant, and then a resin to which an oil repellant or an oil repellant is added is applied. And (b) a method of producing the collection layer 11 using oil-repellent fibers. In the case of (a), for example, the surface of the fiber may be coated with a fluorine-based oil repellent to impart oil repellency.

  In order to coat the fiber surface with a fluorine-based oil repellent, for example, a fluororesin emulsion may be applied to the fiber surface and dried. As a result, the fluororesin can be adhered to the surface of the fiber in a film form. By performing heat treatment after drying, the adhesion of the fluororesin attached to the fiber surface can be enhanced. In order to apply the fluororesin emulsion to the fiber surface, for example, the emulsion may be dipped (impregnated), sprayed and sprayed, or the emulsion is foamed. As other methods, the surface of the fiber can be fluorinated to impart oil repellency by using diluted fluorine gas, low temperature plasma, or sputtering by glow discharge.

  Fluororesin includes tetrafluoroethylene resin, tetrafluoroethylene / perfluoropropyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, chlorotrifluoroethylene resin, ethylene / tetrafluoroethylene copolymer, fluoride Vinylidene resin, vinyl fluoride resin, hexafluoropropylene / vinylidene fluoride copolymer, polyimide-modified fluorine resin, PPS-modified fluorine resin, epoxy-modified fluorine resin, PES-modified fluorine resin, phenol-modified fluorine resin, Examples include acrylate polymers and methacrylate copolymers having a perfluoroalkylethylene group. Also, a fluororesin emulsion can be used. As such an emulsion, Asahi Guard (registered trademark) AG-7000, which is a fluorine resin manufactured by Asahi Glass, for example, can be used.

  The amount of the fluororesin attached is preferably 0.1 to 10% by weight, particularly 0.5 to 2% by weight, based on the weight of the fiber before the fluororesin is attached. By setting the adhesion amount to 0.5% by weight or more, sufficient oil repellency can be imparted to the fiber surface. Moreover, the fall of the air permeability of the filter resulting from excessive adhesion is prevented by making adhesion amount into 10 weight% or less.

  When the fiber itself is made of a material having oil repellency, the above-described various fluororesins can be used as the material.

  As the oil repellent used for the oil repellent treatment, a part of the surfactant can be used in addition to the fluorine-based oil repellent. Such a surfactant can exhibit oil repellency by applying it to a nonwoven fabric and drying it. For example, the oil repellency can be imparted to the fiber by applying a nonionic surfactant, alkyl glucoside, and an amphoteric surfactant, lauramidopropyl betaine, to a nonwoven fabric and drying. In addition, among the fibers in which an oil containing fluorine is applied to the surface, there are fibers in which the fiber surface exhibits oil repellency by heating, and such fibers can also be used in the present invention. Examples of such fibers include Ube Nitto's ultra-oil-repellent nonwoven cotton and UC fiber HR-PLE.

  Examples of the fibers used when producing a nonwoven fabric using oil-repellent fibers include fibers in which fluorine is kneaded and fibers made of a fluororesin. Examples of such fibers include Toyoflon (registered trademark), which is a fluorine fiber manufactured by Toray, and Teflon (registered trademark) manufactured by DuPont.

  The oil-repellent collection layer 11 can be manufactured by the following method. A fiber web that is the basis of the fiber aggregates 11b and 11c is laminated on each surface of the support 11a, and a high-pressure water stream is jetted toward the fiber web in this state. At this time, an oil-repellent fiber is used as one of the fiber aggregates. In addition, when heat-fusible fibers are used as the constituent fibers, the fibers can be fused to form a sheet by blowing hot air onto the laminated web. At this time, as one of the fiber aggregates, a heat-sealable and oil-repellent fiber is used. Examples of such fibers include Ube Nitto's ultra-oil-repellent nonwoven cotton and UC fiber HR-PLE.

  On the other hand, the oil-repellent treated space forming layer 12 can be manufactured by the following method, for example. In other words, the oil-repellent-treated space forming layer 12 is manufactured by subjecting the above-described spunbond nonwoven fabric made of the oil-repellent fibers, or the spunbond nonwoven fabric to the oil-repellent finish, and applying the steel match embossing to make it uneven. it can.

  The multilayer filter 10 of the present embodiment having the above configuration is particularly useful as an oil collecting filter for a range hood as described above, and is also useful as a gas filter such as an air conditioner filter or an exhaust duct filter. It is. It can also be used as a filter for various liquids including an antifouling filter for a drain in a bathroom and a filter for a water purifier. In the multilayer filter 10 of the present embodiment, since the collection layer 11 has a lower air permeability than the space forming layer 12, the air permeability of the multilayer filter 10 is governed by the air permeability of the collection layer 11. Therefore, the air permeability of the multilayer filter 10 is substantially the same as the air permeability of the collection layer 11.

  When the multilayer filter of the present invention is used as an oil collecting filter for a ventilation fan or a range hood, in any case of the above-described embodiments, the constituent fibers are flameproof from the viewpoint of safety. Preferably there is. For example, non-combustible fibers such as glass fiber and carbon fiber, flame retardant fibers such as polyvinyl chloride, polyvinylidene chloride, polyclar, flame retardant polyester, flame retardant acrylic, flame retardant rayon, flame retardant polypropylene, and flame retardant polyethylene are used. It is preferable. Alternatively, it is preferable to blend incombustible fiber and / or flame retardant fiber. A flame-retardant fiber is a fiber having a LOI value of 26 or more.

  If the constituent fiber of the laminated filter is not a non-combustible fiber or a flame-retardant fiber, or if it is a non-combustible fiber or a flame-retardant fiber and its flameproof property is insufficient, it will be halogenated or phosphorous in the post-processing step. A series flame retardant may be applied to the fiber, or a polyboric acid flame retardant may be applied to the fiber. Alternatively, a resin containing a flame retardant may be applied as a binder to the fiber surface to form the coating.

  When the constituent fiber of the filter is not a non-combustible fiber or a flame retardant fiber, a synthetic fiber made of a known fiber-forming synthetic resin, for example, a polyolefin-based material such as polyethylene, polypropylene, polybutylene, polyethylene terephthalate, poly Fibers made of polyester materials such as butylene terephthalate, polyamide materials such as nylon 6 and nylon 66, polyacrylonitrile materials, rayon, and various rubbers can be used. Further, it is also possible to use a vinyl material such as polyvinyl chloride, or a fiber made of vinylidene such as polyvinylidene chloride. Further, fibers made of modified materials, alloys, or mixtures of these materials can also be used.

  Moreover, it is not necessary for all the nonwoven fabric layers which comprise the laminated filter of this invention to be comprised with the above-mentioned flame-retardant nonwoven fabric, and only one layer in a laminated filter, especially a collection layer are comprised with the flame-retardant nonwoven fabric. May be. This is because the trapping layer is located on the stove side when using the filter, and there is a high risk of exposure to flames and heat.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, the collection layer 11 shown in FIG. 4 has the fiber assemblies 11b and 11c on both surfaces of the support 11a, but instead of this, the fiber assembly is laminated only on one surface of the support 11a. Also good. Even if the support is not included, if the space forming layer has sufficient strength, the multilayer filter as a whole can maintain sufficient strength. Therefore, it is not always necessary to include the support 11a.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “% by weight”.

[Example 1]
(1) Production of collection layer An air-through nonwoven fabric having a basis weight of 46 g / m ² was produced. This nonwoven fabric was composed of a core-sheath type composite fiber (fiber diameter: 17 μm) having a core made of polyethylene terephthalate and a sheath made of polyethylene. The nonwoven fabric had an air permeability of 112 m / (kPa · s) and a thickness under a load of 0.3 kPa of 4 mm.

(2) Production of space forming layer A spunbonded nonwoven fabric having a basis weight of 23 g / m ² was produced. This nonwoven fabric was composed of polypropylene fibers (fiber diameter 6.6 dtex). This nonwoven fabric was subjected to steel match embossing to form three-dimensionally. The filling rate of the nonwoven fabric after the three-dimensional shaping was 1.3% under a load of 0.3 kPa, and the thickness was 1.9 mm under the same load. The air permeability was 650 m / (kPa · s).

(3) Manufacture of multilayer filter The obtained collection layer and the space forming layer were overlapped, and were melt-fused and integrated by ultrasonic embossing. As a result, the intended multilayer filter was obtained.

[Examples 2 and 3 and Comparative Examples 1 to 5]
A laminated filter was produced in the same manner as in Example 1 except that the collection layer and the space forming layer shown in Table 1 were used.

Example 4
The collection layer shown in FIG. 4 was manufactured. Polypropylene fibers (fiber diameter 17 μm, fiber length 51 mm) were used as raw materials, and a fiber web having a basis weight of 25 g / m ² was obtained using a conventional card method. A polypropylene lattice net (interfiber distance of 8 to 10 mm, wire diameter of 200 to 300 μm, basis weight of 5 g / m ² ) was used as a support, and after the fiber web was polymerized on the top and bottom, conditions of water pressure of 1 to 5 MPa were used. And entangled with high-pressure jet water jets from a plurality of nozzles to obtain a spunlace nonwoven fabric. Other than that was carried out similarly to Example 1, and manufactured the laminated filter.

Example 5
Everlite (registered trademark) SF · HR-08, which is a polyurethane foam made by Bridgestone, was used as the space forming layer. A multilayer filter was manufactured in the same manner as in Example 1 except for this.

Example 6
Everlite (registered trademark) SF · HR-13, which is a polyurethane foam made by Bridgestone, was used as the space forming layer. A multilayer filter was manufactured in the same manner as in Example 1 except for this.

Example 7
Bonding cloth, which is a polypropylene net made by Nippon Screen, was subjected to steel match embossing and three-dimensionally shaped. A three-dimensionally shaped net was used as a space forming layer. The net before three-dimensional shaping had a wire diameter of 350 μm and an opening of 670 μm. A multilayer filter was manufactured in the same manner as in Example 1 except for this.

Example 8
The collection layer shown in FIG. 4 was manufactured. Polypropylene fibers (fiber diameter 17 μm, fiber length 51 mm) were used as raw materials, and a fiber web having a basis weight of 25 g / m ² was obtained using a conventional card method. A polypropylene lattice net (interfiber distance of 8 to 10 mm, wire diameter of 200 to 300 μm, basis weight of 5 g / m ² ) was used as a support, and after the fiber web was polymerized on the top and bottom, conditions of water pressure of 1 to 5 MPa were used. And entangled with high-pressure jet water jets from a plurality of nozzles to obtain a spunlace nonwoven fabric. However, one of the fiber webs was subjected to fluororesin processing. The fluororesin processing was performed by the following method. Asahi Guard (registered trademark) AG-7000 (solid content 20%), a fluororesin emulsion manufactured by Asahi Glass, was diluted 100 times with water to obtain a liquid having a solid content of 0.05%. About 500% of this liquid was applied to the weight of the nonwoven fabric obtained above. Thereafter, the fluorine treatment was completed by drying with an electric dryer. In this way, 0.25% (vs. fiber weight) was attached as a fluororesin. The obtained collection layer and the space forming layer were overlapped. At this time, the fluorine-treated layer in the collection layer was opposed to the space forming layer. Under this condition, both were melt-fused and integrated by ultrasonic embossing. A multilayer filter was manufactured in the same manner as Example 1 except for these.

[Evaluation 1]
About the laminated filter obtained by the Example and the comparative example, this was attached to the food fan grease filter for Hitachi ranges, VP-60GFS. When the laminated filter is directly attached to the range hood and the wind speed is measured, the measurement error increases due to the pressure difference inside and outside the duct or the gap between the hoods. Therefore, the range hood is simulated as shown in FIG. The wind speed was measured using the apparatus. EC-100T-R313 made by Showa Denki was used for the blower. A cylinder having a diameter of 14 cm (area 154 cm ² ) and a length of 60 cm was attached in front of the cylinder, and a grease filter and a multilayer filter were installed 57 cm above the blower inside the cylinder. For measuring the wind speed, a wind speed measuring machine model 6541 manufactured by Nippon Kanomax Co., Ltd. was used. The measurement was performed 3 cm upwind from the center of the filter (60 cm upwind from the blower). The results are shown in Tables 1 and 2 below. As Reference Example 1, the wind speed in the case of using only a grease filter without a laminated filter was also measured.

[Evaluation 2]
About the multilayer filter obtained by the Example and the comparative example, the antifouling property of the grease filter was evaluated by the following method. The results are shown in Tables 1 and 2 below. In addition, as Reference Example 1, the antifouling property in the case of using only a grease filter without a multilayer filter was also evaluated.
With reference to the oil collection efficiency test of the ventilation unit (kitchen fan) filter (BLT VU-08) in the excellent housing parts performance test method published by Better Living Foundation, the test sequence was performed as follows. FIG. 8 shows this test state.
1. Put 12.5g of cooking oil in a frying pan on a stove and heat for 1 minute.
2. From above, water droplets are dropped at 200 g / 25 minutes to generate oily smoke.
3. Exhaust the generated smoke with a ventilation fan.
4). Oil is collected with a filter when exhausting.
5. The test time for one test is 30 minutes and is performed three times.
6). The filter is removed and the grease filter is visually inspected to evaluate the following three levels.
○ There is no oil on the grease filter.
△ Some oil has adhered to the grease filter.
× A large amount of oil has adhered to the grease filter.

[Evaluation 3]
The multilayer filter needs to secure a certain wind speed at the same time as the antifouling property of the grease filter. If the wind speed is too low, the exhaust capacity decreases and the range hood body is contaminated. A wind speed of 0.4 m / s or more, preferably 0.6 m / s or more is required for the ventilating fan or the range hood to fully perform its function. Even if either the antifouling property or the wind speed that can be secured is lacking, the ability as a filter is not sufficient. Therefore, the overall ability of the multilayer filter was evaluated in the following three stages. The results are shown in Tables 1 and 2 below. In addition, as Reference Example 1, the total ability in the case of using only a grease filter without a multilayer filter was also evaluated.
A: High antifouling property and a wind speed of 0.6 m / s or more can be secured.
○: High antifouling property and a wind speed of 0.4 m / s or more can be secured.
(Triangle | delta): Although antifouling property is high, although a wind speed is less than 0.4 m / s or a wind speed is 0.4 m / s or more, antifouling property is low.
X: Antifouling property is low and the wind speed is less than 0.4 m / s.

  As is clear from the results shown in Tables 1 and 2, the multilayer filters (product of the present invention) obtained in each example are more than single-layer or multilayer filters having the same collection layer obtained in Comparative Examples. It can also be seen that the wind speed and antifouling property are high. Moreover, in order that a ventilation fan and a range hood fully exhibit the function, the wind speed of 0.4 m / s or more is required, and when the air permeability of a collection layer is too low, the comparative examples 4 and 5 As the wind speed is greatly reduced, it is not suitable for practical use. The fan used in the above measurement and evaluation generates wind speed by the same mechanism as that used in a general range hood, and the same phenomenon occurs in an actual range hood. The filter of Example 3 has substantially the same wind speed as the filter of Comparative Example 1. This indicates that there is no effect unless the space forming layer has a thickness equal to or larger than the thickness in the same embodiment. However, since Example 3 has a spunbond layer, the elongation of the entire filter is low, and as a result, it is less likely to sag during use, which is advantageous over Comparative Example 1. In addition, it is advantageous because the collected oil does not easily get through and the antifouling property is high.

  Further, it can be seen that the multilayer filter obtained in each example (product of the present invention) is prevented from being contaminated with the grease filter than the multilayer filter obtained in the comparative example.

FIG. 1 is an exploded perspective view showing an embodiment of the multilayer filter of the present invention. FIG. 2 is an explanatory view showing a state in which the multilayer filter shown in FIG. 1 is attached to a filter attachment member. FIG. 3A is a schematic diagram showing the flow of fluid in the conventional filter, and FIG. 3B is a schematic diagram showing the flow of fluid in the multilayer filter of the present invention. FIG. 4 is a schematic view showing one embodiment of a collection layer used in the multilayer filter of the present invention. FIG. 5 is a schematic view showing a support used in the multilayer filter shown in FIG. FIG. 6 is a schematic diagram showing a state of collecting oil droplets when an oil-repellent fiber is used for a part of the collection layer. FIG. 7 is a schematic diagram showing a method for measuring the wind speed of the range hood. FIG. 8 is a schematic view showing a method for evaluating the antifouling property of a grease filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated filter 11 Collection layer 11a Support body 11b, 11c Fiber assembly 12 Space formation layer 20 Filter attachment member 21 Shielding part A Oil component F1 Fiber with oil repellency F2 Fiber without oil repellency M Oil film

Claims (8)

A multilayer filter having a collection layer and a space forming layer,
The multilayer filter is used so that the space forming layer is located on the downstream side of fluid suction,
The space forming layer has a filling rate of 1 to 7%, which is a ratio (%) of the volume of the constituent material of the space forming layer in the apparent volume of the space forming layer under a load of 0.3 kPa. And the thickness under the same load is 1-12 mm,
The multilayer filter which the said collection layer consists of a nonwoven fabric with a fiber diameter of 7-35 micrometers.   The multilayer filter according to claim 1, wherein the space forming layer is used by being attached to the attachment member so as to face the attachment member having a shielding portion. The air permeability of the space forming layer is less than 400 to 1000 m / (kPa · s),
The laminated filter according to claim 1 or 2, wherein the trapping layer has an air permeability of less than 25 to 400 m / (kPa · s).   The multilayer filter according to claim 3, wherein the space forming layer has a breaking strength of 1 to 150 N / 25 mm or an elongation of 1 to 15% when a tensile stress of 0.5 N / 25 mm is applied.   The multilayer filter according to claim 3 or 4, wherein the space forming layer is formed by subjecting a nonwoven fabric to three-dimensional secondary processing.   The multilayer filter according to claim 5, wherein the space forming layer is made of a spunbond nonwoven fabric subjected to steel match embossing. The collection layer has a first layer facing outward and a second layer facing the space forming layer, and the surface of the constituent fibers of the second layer has oil repellency,
The multilayer filter according to any one of claims 1 to 6, which is used as an oil collecting filter.   The multilayer filter according to any one of claims 1 to 7, wherein a surface of a constituent fiber of the space forming layer has oil repellency and is used as an oil collecting filter.

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