JP2005288368A - Dust collecting filter material for cleaner and dust collecting filter unit for cleaner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust collecting filter material for a cleaner which is capable of easily removing attached dust and can be utilized repeatedly while maintaining the quantity of air flow. <P>SOLUTION: The filter material 1 comprises a PTFE porous film 2, an air permeable substrate 4 and a net-like body 3. Therein, the net-like body 3 is arranged on at least one side surface of laminate containing the PTFE porous film 2 and the air permeable substrate 4 and at least one side surface of the filter material 1 is let to be rugged. When at least one side surface of the filter material 1 is rugged, dust including oil is hardly attached, even if the dust is attached, it can be easily eliminated and the degradation of air permeability can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dust collection filter medium for a vacuum cleaner and a dust collection filter unit for a vacuum cleaner using the same.

  Conventionally, a disposable pack using a material such as paper has been used for a dust collecting filter unit for a vacuum cleaner for convenience (see Patent Document 1). However, the disposable pack has problems in terms of cost and resource saving. Further, in recent years, due to increasing interest in health and the environment, it has been strongly required to clean the exhaust, and leakage of fine dust that cannot be collected by the disposable pack has become a problem.

  Therefore, in recent years, it has become common to employ a reusable dust pack (see Patent Document 2) and a secondary filter for collecting fine dust passing through the pack. Among them, the dust pack and the secondary filter using a porous film of polytetrafluoroethylene (PTFE) as a filter medium are attracting attention (see Patent Document 3). The PTFE porous membrane has a low pressure loss (high air flow rate) and high dust collection efficiency, and efficiently collects fine particles that adversely affect the body, such as viruses and allergens. Similarly, when an electret filter (see Patent Document 4) showing a high collection efficiency with a low pressure loss (high air flow rate) is moistened with moisture in the exhaust, the dust collection efficiency is reduced. The PTFE porous membrane does not show a decrease in collection efficiency even when it is moistened with moisture in the exhaust gas. This is because the dust collection mechanism of the PTFE porous membrane mainly has a blocking effect by fine fibers, which is different from the electrostatic collection of the electret filter.

  However, when the PTFE porous membrane filter medium is used under normal conditions, the air permeability can be recovered by regular cleaning and can be used repeatedly, but rarely due to clogging of the filter medium, There was a problem that the ventilation resistance was remarkably increased and it was impossible to recover.

Japanese Utility Model Publication No. 50-116253 JP 2000-166829 A Japanese Patent Laid-Open No. 2000-300921 JP 54-53365 A

  Accordingly, an object of the present invention is to provide a filter material for a vacuum cleaner that is used for a vacuum cleaner dust collection filter unit that is not clogged and that prevents a reduction in air flow. It is.

  In order to achieve the above object, the filter medium of the present invention includes a polytetrafluoroethylene (PTFE) porous membrane, a breathable support, and a net-like body, and the net-like body comprises the PTFE porous body. The filter medium is arranged on at least one surface of a laminate including a membrane and the air-permeable support.

  The present inventor has made various studies on the cause of clogging of the PTFE porous membrane filter medium. As a result, it was found that the cause of the clogging was due to fine dust containing oil. That is, when normal dust is collected by the PTFE porous membrane filter medium, the dust forms a cake layer deposited on the surface of the membrane. The cake layer easily falls off due to the non-adhesiveness and low friction property of PTFE when the filter medium is cleaned, and air permeability is restored. However, when oil is contained in the dust sucked by the vacuum cleaner, the oil wets the dust and forms a highly sticky mud-like cake layer. This cake layer adheres to the surface of the PTFE porous membrane and increases the ventilation resistance. And it is difficult to remove the mud-like cake layer containing this oil component by normal cleaning. Therefore, the present inventors have further researched based on this finding, the filter medium includes a net-like body disposed on at least one surface of the laminate, and at least one surface of the filter medium It has been found that if the is made uneven, it can be easily removed even if it is a mud-like cake layer made of oil-containing dust.

  Thus, since the filter medium of the present invention includes a net-like body and at least one surface of the filter medium is uneven, the contact area between the surface of the filter medium and the cake layer can be reduced. As a result, it is difficult for dust containing oil to adhere to the surface of the filter medium, and even if it adheres, it can be easily removed, and repeatedly while maintaining the air flow rate without causing clogging. Available.

  The average height of irregularities on at least one surface of the filter medium formed by the net-like body is preferably 100 μm to 500 μm. In addition, in this invention, the average height of unevenness means the average value of the height from the concave bottom part of a concave part to the convex top part of a convex part. In addition, the average height of the unevenness is measured by a method described later.

In addition, the average distance between adjacent convex portions on the surface of the filter medium is preferably 300 μm to 700 μm. In addition, in this invention, the average distance of the convex part which adjoins means the average value of the distance between each convex top part of the convex part which adjoins. In addition, the average distance of the said adjacent convex part is measured by the below-mentioned method.
The shape of the unevenness on the surface of the filter medium is not particularly limited.

In the present invention, the net-shaped body has a basis weight and 50μm~1000μm less of the thickness of ^{10g / m 2 ~200g / m 2} , preferably a thermoplastic plastic. This is because the surface of the net-like body is uneven, so that at least one surface of the filter medium can be easily made uneven.

  The filter medium of the present invention includes one or more breathable supports. This is to maintain the strength of the filter medium by this support. The laminate including the PTFE porous membrane and the air-permeable support includes one or more PTFE porous membranes and one or more air-permeable supports. The form of the lamination is not particularly limited. For example, a laminate including 1 PTFE porous membrane, 1 air-permeable support, 2 PTFE porous membrane, 1 laminate including 1 air-permeable support, and 2 PTFE porous A laminate including a membrane and the two air-permeable supports is exemplified. Further, the order of stacking is not particularly limited.

A filter medium whose pressure loss exceeds 0 Pa (0 mmH ₂ O) and is 300 Pa (30.6 mmH ₂ O) or less is preferable. The pressure loss is greater than 0Pa (0mmH ₂ O), and 200Pa (20.4mmH ₂ O) or less is more preferable. Further, the collection efficiency of the filter medium is preferably 90% or more and 100% or less, more preferably 99% or more and 100% or less.

The dust collecting filter unit for a vacuum cleaner of the present invention includes the filter medium of the present invention.
The vacuum cleaner of this invention contains the dust collection filter unit for vacuum cleaners of this invention.

  Next, the filter medium of the present invention will be described with examples.

The filter medium includes one or more PTFE porous membranes. In the PTFE porous membrane, the thickness is appropriately determined depending on the size of the filter medium to be produced, etc., and is, for example, in the range of 2 to 50 μm, and the pore diameter is, for example, in the range of 0.5 to 50 μm. It is. The pressure loss of the PTFE porous membrane is preferably as low as possible. For example, the pressure loss is in a range of 300 Pa (30.6 mmH ₂ O) or less and over 0 Pa (0 mmH ₂ O), preferably 200 Pa (20.4 mmH ₂ O). ) And below 0 Pa (0 mmH ₂ O). Moreover, the higher the collection efficiency of the PTFE porous membrane, the better. For example, it is in the range of 90% to 100%, preferably 95% to 100%, more preferably 99% to 100%. It is. The pressure loss and the collection efficiency are measured by the method described later.

  In the PTFE porous membrane, the thickness is appropriately determined depending on the size of the filter medium to be produced, etc., and is, for example, in the range of 2-100 μm, and the pore diameter is, for example, in the range of 0.5-50 μm It is.

  The PTFE porous membrane can be manufactured, for example, as follows. That is, first, a liquid lubricant is added to the unfired PTFE fine powder and mixed uniformly. The PTFE fine powder is not particularly limited, and a commercially available product can be used. The liquid lubricant is not particularly limited as long as it can wet the PTFE powder and can be removed later. Hydrocarbon oils such as naphtha, white oil, liquid paraffin, toluene, xylene, alcohols, ketones And solvents of esters and the like can be used. These may be used alone or in combination of two or more.

  The addition ratio of the liquid lubricant to the PTFE fine powder is appropriately determined depending on the type of the PTFE fine powder, the type of the liquid lubricant, the sheet molding conditions described later, and the like. For example, for 100 parts by weight of the PTFE fine powder The liquid lubricant is in the range of 15 to 35 parts by weight.

  Next, the mixture is formed into a sheet in an unfired state. Examples of the forming method include a rolling method in which the mixture is extruded into a rod shape and then rolled with a pair of rolls, and an extrusion method in which the mixture is extruded into a sheet shape. Moreover, you may combine both methods. Although the thickness of this sheet-like molded object is suitably determined by the conditions of the extending | stretching performed later, etc., it is the range of 0.1-0.5 mm, for example.

  The liquid lubricant contained in the obtained sheet-like molded body is preferably removed by a heating method, an extraction method, or the like before the subsequent stretching step. The solvent used in the extraction method is not particularly limited, and examples thereof include normal decane, dodecane, naphtha, kerosene, and sumoyl.

  Next, it extends | stretches with respect to the said sheet-like molded object. The sheet-like molded body is made porous by uniaxial stretching or biaxial stretching at a temperature not higher than the melting point (327 ° C.) of PTFE. For example, in the longitudinal direction of the sheet-shaped molded body, the sheet is stretched at a temperature of 150 to 327 ° C. so that the length thereof is in the range of 2 to 60 times the length before stretching, and then the sheet In the width direction of a molded object, it extends | stretches at the temperature of 40-150 degreeC so that the length may become the range of 10-60 times the length before extending | stretching. After the stretching, the stretched state is maintained and heated to a temperature equal to or higher than the melting point (327 ° C.) of PTFE and fired to improve mechanical strength and increase dimensional stability. Thus, a PTFE porous membrane can be produced. In addition, in this invention, the manufacturing method of a PTFE porous membrane is not limited to the above-mentioned method, You may create with another method and may use a commercial item.

In the filter medium of the present invention, the uneven surface is a thermoplastic plastic net having a thickness of 10g / m ² ~200g / m ² or less of the basis weight and 50Myuemu～1000myuemu, the breathable support and the porous PTFE membrane The laminate is preferably formed by being laminated on at least one surface of a laminate including the body. It is more preferable that the thermoplastic net is formed by laminating on the PTFE porous film of the laminate. Examples of the thermoplastic plastic include polyolefin (polyethylene, polypropylene, etc.), polyvinyl chloride, polystyrene, etc. Among them, polyolefin is preferable.

  In the present invention, a metal mesh (metal net) can also be used as the net-like body. The metal mesh is made of a material such as iron, stainless steel, or copper, and the thickness is preferably 50 to 1000 μm. The distance between the meshes of the metal mesh is preferably 300 to 700 μm. This is because, when such a metal mesh is used, the average distance between adjacent convex portions on the surface of the filter medium of the present invention is 300 to 700 μm.

  In the filter medium of the present invention, examples of the method for adhering the net-like material on the laminate include a method of adhering with an adhesive, a method of fusing and adhering by heating, and the like. In the present invention, “adhesion” is not limited to adhesion using an adhesive, but is a broad concept including heat welding and the like. As the adhesive, a two-component mixed type or a self-crosslinking type adhesive by heat can be used. As the two-component mixed type, an epoxy resin is suitable, and as the self-crosslinking type by heat, a vinyl acetate-ethylene copolymer or an ethylene-vinyl chloride copolymer is suitable. In the method using thermal welding, when a polyolefin net is used as the net-like body, the polyolefin net has a melting point as low as a few tens of degrees Celsius, so that it can be thermally welded to the laminate at a relatively low temperature. Therefore, when a polyolefin net is used as the net-like body, the net-like body can be preferably adhered on the laminate, more preferably on the PTFE porous membrane surface of the laminate by a method using heat welding.

  Next, an example of the filter medium of the present invention is shown in the sectional view of FIG. 1 and the perspective view of FIG. As shown in the figure, in this filter medium 1, a thermoplastic net 3 as a net-like body is bonded to a PTFE porous membrane 2, and the surface of the filter medium 1 is uneven. A breathable support 4 is bonded to the surface of the porous PTFE membrane 2 opposite to the bonding surface. As the PTFE porous membrane and the thermoplastic net, the same ones as described above can be used. The filter medium of the present invention is preferably used so that the net-like body is on the upstream side. Thereby, the adhesion of dust to the filter medium surface is reduced, and the adhered dust can be easily removed.

Examples of the breathable support include woven fabric, non-woven fabric, metal or plastic mesh, metal or plastic net, and plastic foam. In addition, a nonwoven fabric is most preferably used for the said air permeable support body from the point of cost. As the fibers, for example, semi-synthetic fibers such as cellulose and viscose, and synthetic fibers such as polyester, polyolefin, polyamide, acrylic, polysulfone, polyamideimide, polyimide, polyphenylene sulfide, and polyvinylidene fluoride may be used. The air-permeable support has a basis weight of, for example, 10 g / m ² or more and 100 g / m ² or less, preferably 10 g / m ² or more and 80 g / m ² or less.

  The PTFE porous membrane and the air-permeable support are preferably bonded and integrated. The bonding method is not particularly limited, but it is preferable to reduce the bonding area in order to maintain the air permeability of both. Examples of the bonding method include a method of laminating with a heat-meltable net or mesh sandwiched therebetween, a method of applying and bonding an adhesive in fine dots or lines. As the adhesive, a two-component mixed type or a self-crosslinking type adhesive by heat can be used. As the two-component mixed type, an epoxy resin is suitable, and as the self-crosslinking type by heat, a vinyl acetate-ethylene copolymer or an ethylene-vinyl chloride copolymer is suitable.

  From the viewpoint of cost, the bonding method is preferably a method of laminating a non-woven fabric having a thermal adhesive property on a PTFE porous membrane in advance. For example, when a non-woven fabric made of a thermoplastic resin such as polyethylene is partially or entirely laminated with a PTFE porous membrane with appropriate heat and pressure, some of the fibers melt and the PTFE porous membrane It is possible that only the fiber in the part in contact with the heat welds. Therefore, in the portion where the non-woven fabric fibers and the PTFE porous membrane are not in contact with each other, the pores are not blocked by heat welding, so that the air permeability of the PTFE porous membrane can be maintained.

  3 and 4 each show another example of the filter medium of the present invention. FIG. 3 is a diagram showing a structure in which a plurality of (two in FIG. 3) PTFE porous membranes 2 and a breathable support 4 are bonded in this order to form a laminate, and the surface of the PTFE porous membrane 2 of this laminate A thermoplastic net 3 as a net-like body is bonded on top. The filter medium 10 shown in FIG. 3 has an uneven surface on one surface by the thermoplastic net 3.

  FIG. 4 shows that a PTFE porous membrane 2, a breathable support 4, a PTFE porous membrane 2 and a breathable support 4 are bonded in this order to form a laminate, and the PTFE porous material on the upper side of the laminate is further formed. This is a filter medium 20 having a structure in which a thermoplastic net 3 is bonded to a membrane 2. The filter medium 20 of FIG. 4 is also uneven on one surface due to the thermoplastic net 3.

  The filter medium of the present invention is used with the net-like body on the upstream side. Thereby, the adhesion of dust to the filter medium surface is reduced, and the adhered dust can be easily removed.

  The filter medium of the present invention may be attached to a frame as a dust collecting filter unit for a vacuum cleaner. Further, this filter unit is used by being attached to a dust collecting part of a general vacuum cleaner. The filter medium can be used repeatedly by periodically cleaning it. This cleaning method is not particularly limited, and examples thereof include a method of blowing air, washing with water, and washing with a detergent solution.

  Next, examples of the present invention will be described together with comparative examples. In addition, the measuring method of each characteristic of the PTFE porous membrane in an Example and a comparative example, a filter material, the filter material of paper filter bags, and a nonwoven fabric is as showing below.

(1) Pressure loss The pressure loss was measured according to the test method of the filter material for collecting dust samples in the gas of JIS K 0901. The pressure loss (unit: Pa and mmH ₂ O) is adjusted to a pressure gauge (manometer) by adjusting the wind speed to 5.3 cm / sec for the sample (PTFE porous membrane, filter medium, or filter medium for paper filter bag, the same applies hereinafter). Measured with Note that the wind speed for the sample was set to 5.3 cm / second because, in general, the airflow resistance of a high-performance air filter is measured based on the MIL-TRY STANDARD MF-F-51079D. It is a thing.

(2) Collection efficiency The collection efficiency was measured using particles of dioctyl phthalate (DOP) having a particle size of 0.3 to 0.5 μm according to the aerosol collection performance test method of an air filtration depth filter for sterilization according to JIS K 3803. Measured. The collection efficiency is according to the following formula.

Collection efficiency (%) = [1− (downstream particle concentration / upstream particle concentration)] × 100
Unit of the number of particles on the downstream side: pieces / liter Unit of the number of particles on the upstream side: pieces / liter

(3) Weight per unit area The net amount was obtained by sampling the net at 100 cm ² and measuring the weight with an electronic balance to determine the mass per m ² .

(4) Average height of irregularities Using a laser microscope (HA-100 (trade name), manufactured by Lasertec Co., Ltd.), the surface of the net-like body of the filter medium is photographed, from the concave bottom of the concave part to the top of the convex part. The height was measured. Twelve or more points are measured, and the average value is defined as the average height of the irregularities.

(5) Average distance between adjacent convex portions Using a laser microscope (HA-100 (trade name), manufactured by Lasertec Corporation), the surface of the net-like body of the filter medium is photographed, and the adjacent convex portions are obtained from the planar image. The distance between each convex part was measured. 12 points or more are measured, and the average value is defined as the average distance of the convex portions.

PTFE porous membrane (manufactured by Nitto Denko Corporation, Microtex NTF1033 (trade name), thickness 15 μm, nominal pore diameter 3.0 μm, pressure loss 80 Pa (8.2 mmH ₂ O), collection efficiency 90%), polyethylene terephthalate ( PET / polyester (PE) core-sheath nonwoven fabric (manufactured by Unitika Ltd., Elves TO703WDO (trade name), thickness 160 μm, weight per unit area 70 g / m ² , melting point 129 ° C. of sheath PE) (support), A heat-sealing is performed by continuously laminating from a PTFE porous membrane side with a pair of heat rolls heated to 135 ° C., and the two are integrated to obtain a laminate for a filter medium (thickness 160 μm, pressure loss 98 Pa (10 mmH ₂ O) and a collection efficiency of 90%). In addition, the PTFE porous membrane surface of this laminated body for filter media is smooth.

Next, the laminate for the filter medium and polyethylene net (Applied Extrusion Technologies, Inc., DELNET X550 (trade name), thickness: 110 μm, basis weight: 16 g / m ² ) In such a way that the polyethylene net faces the PTFE porous membrane of the laminate for filter media. A filter medium having the same structure as in FIG. 1 (thickness: 270 μm, pressure loss: 156.8 Pa (16 mmH ₂ O), collection efficiency: 90%, uneven height: 110 μm) The average distance between adjacent convex portions was 590 μm).

The filter filter laminate obtained in Example 1 and a polyethylene net (USA, Cowed Plastics, Inc., XN6065 (trade name), thickness 360 μm, basis weight 108 g / m ² ) Was laminated so that the polyethylene net faced the PTFE porous membrane of the laminate for filter media. Heated at 160 ° C. from the polyethylene net side and thermally welded (same structure as in FIG. 1), filter media (thickness 510 μm, pressure loss 156.8 Pa (16 mmH ₂ O), collection efficiency 90%, average height of irregularities 360 μm, and the average distance between adjacent convex portions was 750 μm).

(Comparative Example 1)
As the filter medium, the laminate for filter medium of Example 1 (thickness 160 μm, pressure loss 98 Pa (10 mmH ₂ O), collection efficiency 90%) was used. In addition, the PTFE porous membrane surface of this laminated body for filter media is smooth.

(Comparative Example 2)
As a filter medium, commercially available disposable paper packs for general vacuum cleaners (paper pack filter GP-55F (trade name), manufactured by Hitachi Home & Life Solutions Co., Ltd., thickness 140 μm, pressure loss 63.7 Pa (6.5 mmH ₂ O ), Collection efficiency 70%). This vacuum cleaner paper pack was composed of hemp pulp, wood pulp and polyester binder staple fibers for papermaking.

Dust Suction Test Each of the filter media of Examples 1 and 2 and Comparative Examples 1 and 2 was manufactured by using a general household vacuum cleaner (Z5210 Silence (trade name), manufactured by Electrolux Co., Ltd. (Sweden)). The model dust (100 g) was sucked into 10 times. As the model dust, a mixture of 15 kinds of test dust described in JIS Z8901 and cooking vegetable oil (oil content) (0.5% by weight with respect to the dust) was used. After suction of the model dust, the dust adhered to the filter medium was removed using an air gun (distance to the filter medium of 10 cm, air pressure 3.0 kg / cm ² , time 15 seconds). The pressure loss was measured for each of the filter media after removing the dust. The results are shown in Table 1 below.

  As can be seen from Table 1, even though the filter media of Examples 1 and 2 sucked dust containing oil, they were removed by wiping with an air gun, and a decrease in air permeability was suppressed. On the other hand, the air filters of Comparative Examples 1 and 2 were clogged due to the suction of dust containing oil, and could not be removed with an air gun, resulting in a decrease in air permeability.

  The filter medium of the present invention can be used for household or industrial vacuum cleaners, for example.

It is sectional drawing of an example of the filter material of this invention. It is a perspective view of an example of the filter media. It is sectional drawing of the other example of the filter material of this invention. It is sectional drawing of the further another example of the filter material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filter filter medium 2 PTFE porous membrane 3 Thermoplastic net 4 Breathable support 10 Filter filter medium 20 Filter filter medium

Claims (4)

A dust collection filter medium for a vacuum cleaner, comprising: a polytetrafluoroethylene (PTFE) porous membrane, a breathable support, and a net-like body, wherein the net-like body comprises the PTFE porous membrane and the vent A filter medium, which is disposed on at least one surface of a laminate including a conductive support. ^2. The filter medium according to claim 1, wherein the net-like body has a basis weight of 10 g / m ^{2 to} 200 g / m ² and a thickness of 50 μm to 1000 μm, and is made of a thermoplastic. A dust collecting filter unit for a vacuum cleaner comprising the filter medium according to claim 1. The vacuum cleaner containing the dust collection filter unit for vacuum cleaners of Claim 3.

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