JP2005253711A - Air filter medium for vacuum cleaner and air filter unit for vacuum cleaner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air filter medium for a vacuum cleaner capable of easily removing stuck dust and being repeatedly utilized while maintaining a ventilation amount. <P>SOLUTION: In the air filter medium 10 for the cleaner including a PTFE porous film 11, the surface of the PTFE porous film is made oil repellent. When the surface of the PTFE porous film is oil repellent, the oil-containing dust is not easily stuck, it is easily removed even when it is stuck, and the decline of air permeability is prevented. Oil repellency is imparted by performing treatment with a fluorine oil repellency treating agent. As the fluorine oil repellency treating agent, an acrylic polymer having a fluorine side chain, an urethane polymer having the fluorine side chain and a silicon polymer having the fluorine side chain can be used. It is preferable that the PTFE porous film 11 is integrated with a support material 12 of nonwoven fabric or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Conventionally, a disposable pack using a material such as paper has been used for a vacuum cleaner air filter unit 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 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 an air filter medium are attracting attention (see Patent Document 2). 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 the electret filter (see Patent Document 3) showing high collection efficiency with low pressure loss (high air flow) is moistened with moisture in the exhaust, the dust collection efficiency decreases. Thus, the PTFE porous membrane does not show a decrease in the 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 air filter medium is used under normal conditions, the air permeability can be restored and reused by periodic cleaning, but in rare cases, the air filter medium is clogged. Thus, there is a problem that the ventilation resistance is remarkably increased and cannot be recovered.
Japanese Utility Model Publication No. 50-116253 Japanese Patent Laid-Open No. 2000-300921 JP 54-53365 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an air filter medium for a vacuum cleaner that is not clogged and in which a reduction in the air flow rate is prevented.

  In order to achieve the above object, the air filter medium for a vacuum cleaner according to the present invention is an air filter medium for a vacuum cleaner including a PTFE porous membrane, and the surface of the PTFE porous membrane is oil-repellent. The air filter medium is characterized.

  The present inventors have made various studies on the cause of clogging of the PTFE porous membrane air 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 air filter medium made of the PTFE porous membrane, the dust forms a cake layer deposited on the surface of the membrane. This cake layer easily falls off due to the non-adhesiveness and low friction property of PTFE when the air 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 conducted further research based on this finding, and if the PTFE porous membrane surface is oil-repellent, it can be easily removed even if it is a mud-like cake layer made of oil-containing dust. We have found that it is possible to achieve the present invention.

  Thus, since the air filter medium for vacuum cleaner of the present invention uses a PTFE porous membrane whose surface is oil repellent, it is difficult for dust containing oil to adhere, Can be easily removed, and can be repeatedly used while maintaining the air flow rate without causing clogging.

  The oil repellency is preferably imparted by an oil repellent treatment with a fluorine-based oil repellent treatment agent. This is because the fluorine-based oil repellent treatment agent can impart higher non-adhesiveness and lower friction than PTFE, prevent adhesion of dust containing oil, and facilitate removal of dust by cleaning.

  The fluorine-based oil repellent treatment agent is preferably at least one of an acrylic polymer having a fluorine-containing side chain, a urethane polymer having a fluorine-containing side chain, and a silicone polymer having a fluorine-containing side chain.

  The fluorine-based oil repellent treatment agent is preferably a treatment agent having a structure represented by the following formula (1).

CH ₃
｜
_{- (C-CH 2) n} -
| (1)
_{CO-C m H 2m -C x} F 2x + 1
‖
O
In the formula (1), n is a positive integer representing the number of repeating units, and m and x are positive integers.

  In the formula (1), n is, for example, in the range of 5 to 5000, m is, for example, in the range of 1 to 10, preferably in the range of 2 to 4, and x is, for example, 2 to 2. It is the range of 18, Preferably it is the range of 5-10.

  The air filter medium for a vacuum cleaner of the present invention preferably includes a support material. This is because the strength is increased if there is a support material.

  Next, the air filter medium for a vacuum cleaner of the present invention will be described with an example.

  An example of the air filter medium for a vacuum cleaner of the present invention is shown in the sectional view of FIG. As shown in the figure, in this air filter medium 10, a PTFE porous membrane 11 is adhered to a support material 12, and oil repellency is imparted to the surface of the PTFE porous membrane 11 opposite to the adhesion surface.

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

  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, and the conditions of sheet molding described later. 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 plate shape to form a sheet. 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, for example, a heating method or an extraction method 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 air filter medium of the present invention, as shown in FIG. 1, a support material may be used for the purpose of reinforcing the porous PTFE membrane. As the support material, a breathable member using fibers is suitable. The shape of the support material is not particularly limited, and for example, woven fabric, non-woven fabric, metal or plastic mesh, metal or plastic net, plastic foam and the like can be used. The support material is most preferably a non-woven fabric from the viewpoint 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 PTFE porous membrane and the support material are 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, a part of the fiber melts and the PTFE porous membrane Adhere with. Since this adhesion is limited to the non-woven fiber, air permeability is ensured in the part without fiber.

  Next, imparting oil repellency to the PTFE porous membrane surface can be performed by, for example, an oil repellent treatment agent. As the oil repellent treatment agent, as described above, a fluorine-based oil repellent treatment agent is preferable. As such an oil repellent treatment agent, a commercially available product may be used. For example, trade name Unidyne manufactured by Daikin Corporation may be used. In addition, examples of the oil repellent agent having the structure of the formula (1) include trade name X-70-029B manufactured by Shin-Etsu Chemical Co., Ltd. and trade name SFC-200 manufactured by Seimi Chemical Co., Ltd. Examples of the silicone-based polymer oil repellent agent include trade name KP-801M manufactured by Shin-Etsu Chemical Co., Ltd. The treatment method with the oil repellent treatment agent is not particularly limited. For example, the PTFE porous membrane is immersed in the oil repellent treatment agent solution and then dried, and the PTFE porous membrane is coated with the oil repellent treatment agent solution, and thereafter There are methods such as drying. The concentration of the oil repellent treatment agent solution is, for example, 0.1 to 20% by weight, preferably 1 to 10% by weight. Examples of the solvent used in the oil repellent treatment solution include a fluorine-based solvent having a high affinity for the fluorine side chain, for example, trade name Fluorinert manufactured by Sumitomo 3M Limited. The conditions for the immersion treatment are not particularly limited, but for example, a temperature of 5 to 30 ° C. and an immersion time of about 2 to 60 seconds are preferable. The coating method is not particularly limited, and examples thereof include a spray method, a spin coating method, a doping method, and a roll coater method. Moreover, although the drying after immersion or application | coating is not restrict | limited, Heat drying at 40-120 degreeC is preferable. In addition, it may be air-dried or may be dried by blowing hot air. In the present invention, the oil repellent treatment may be performed on the entire surface of the PTFE porous membrane or a part thereof. Moreover, when the support material and the PTFE porous membrane are bonded, an oil repellent treatment may be performed on the surface opposite to the bonding surface.

  The air filter medium for a vacuum cleaner of the present invention may be attached to a frame as an air filter unit. Further, this air filter unit is used by being attached to a dust collecting part of a general vacuum cleaner. The air filter medium for a vacuum cleaner of the present invention 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.

An air filter medium having the structure shown in FIG. 1 was produced according to the method described above. That is, a PTFE porous membrane (manufactured by Nitto Denko Corporation, product name NTF1033, thickness 15 μm, pore diameter 3.0 μm) and polyethylene terephthalate (PET) / polyester (PE) core-sheath structure nonwoven fabric (manufactured by Unitika Ltd., trade name Elves TO703WDO) Adhesion by continuous heat lamination from the PTFE porous membrane side with a pair of heat rolls heated to 135 ° C., with a basis weight of 70 g / m ² , a thickness of 160 μm, and a melting point of sheath core PE of 129 ° C. The both were integrated. The pressure loss of the laminate measured by the method described later was 10 mmH ₂ O.

Next, a treatment liquid (oil repellent treatment agent concentration) prepared by dissolving an oil repellent treatment agent (trade name X-70-029B manufactured by Shin-Etsu Chemical Co., Ltd.) in a fluorine-based solvent (trade name Fluorinert FC-726 manufactured by Sumitomo 3M). 1.0 wt%), the laminate was dipped, then pulled up, and dried at 90 ° C. for 15 minutes, whereby the PTFE porous membrane surface was oil-repellent treated. In this way, a target air filter medium was obtained. The molecular structure of the trade name X-70-029B manufactured by Shin-Etsu Chemical Co., Ltd. is n = 2000, m = 2, and x = 8 in the formula (1). When n-dodecane (C ₁₂ H ₂₆ ) was dropped onto the air filter medium subjected to the oil repellent treatment at room temperature, it did not penetrate.

An air filter medium was prepared in the same manner as in Example 1 except that as the oil repellent agent, trade name S-Coat SIF-200 manufactured by Seimi Chemical Co. was used instead of trade name X-70-029B manufactured by Shin-Etsu Chemical Co., Ltd. . The molecular structure of Seimi Chemical Co., Ltd. trade name SF Coat SIF-200 is n = 2000, m = 2, and x = 8 in the formula (1). When n-dodecane (C ₁₂ H ₂₆ ) was dropped onto the air filter medium subjected to the oil repellent treatment at room temperature, it did not penetrate.
(Comparative Example 1)
In the same manner as in Example 1, a core-sheath nonwoven fabric was laminated on the PTFE porous membrane, and this was used as an air filter medium (no oil repellent treatment). When n-dodecane (C ₁₂ H ₂₆ ) was dropped onto the air filter medium not subjected to the oil repellent treatment at room temperature, it quickly penetrated.
(Comparative Example 2)
A commercially available disposable paper pack for a vacuum cleaner made of hemp pulp, wood pulp, and papermaking polyester binder short fiber, trade name “CP-B1” (sales by the Japan Cooperative Association) was used as an air filter medium. When n-dodecane (C ₁₂ H ₂₆ ) was dropped into the disposable paper pack at room temperature, it quickly penetrated.

The pressure loss and thickness of the air filter media of Examples 1 and 2 and Comparative Examples 1 and 2 thus obtained are shown in Table 1 below. The pressure loss was measured by the following method.
(Pressure loss)
A sample of a predetermined shape cut out from the air filter medium is set in a circular holder having an effective area of 100 cm ² , while supplying atmospheric dust from the inlet side, giving a pressure difference between the inlet side and the outlet side, The air dust was adjusted to 5.3 cm / second and allowed to pass through, and the pressure loss (unit: mmH ₂ O) was measured with a pressure gauge (manometer). The atmospheric dust refers to dust floating in the atmosphere.

つぎに、前記各実施例１，２および比較例１，２のエアフィルタ濾材を、一般的な家庭用掃除機の塵埃捕集部に取り付け、モデル塵埃を吸引した。モデル塵埃には、ＪＩＳ Ｚ ８９０１に従い、試験用ダスト１５種に油分として料理用植物油を重量比０．５％混合したものを用いた。前記吸引は、モデル塵埃１００ｇを１０回に分けて吸引することにより行った。吸引後、エアガンを用い、圧力３．０ｋｇ／ｃｍ^２の空気をエアフィルタ濾材に吹き付けて塵埃を払い落とした。払い落とし時のエアガンとサンプルの距離は１０ｃｍ、吹き付け時間は１５秒である。その後、エアフィルタ濾材の圧力損失を前述の方法により測定した。その結果を、下記の表２に示す。

Next, the air filter media of Examples 1 and 2 and Comparative Examples 1 and 2 were attached to a dust collecting part of a general household vacuum cleaner, and model dust was sucked. As the model dust, according to JIS Z 8901, 15 kinds of test dust mixed with cooking vegetable oil 0.5% by weight as oil was used. The suction was performed by sucking 100 g of model dust in 10 steps. After suction, an air gun was used to blow off dust at a pressure of 3.0 kg / cm ² onto the air filter medium. The distance between the air gun and the sample at the time of dropping is 10 cm, and the spraying time is 15 seconds. Thereafter, the pressure loss of the air filter medium was measured by the method described above. The results are shown in Table 2 below.

前記表１および表２から分かるように、実施例１，２のエアフィルタ濾材は、油分を含んだ塵埃を吸引しても、エアガンで払い落とすことによって塵埃が排除され、通気性の低下が抑制された。これに対し、比較例１，２のエアフィルタでは、油分を含んだ塵埃の吸引により、目詰まりを起こし、エアガンで払い落とすことができず、通気性が低下した。

As can be seen from Table 1 and Table 2, the air filter media of Examples 1 and 2 can eliminate dust by removing it with an air gun even if the oil-containing dust is sucked in, and suppress deterioration in air permeability. It was done. 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 wiped off with an air gun, resulting in a decrease in air permeability.

  The air filter medium for a vacuum cleaner according to the present invention does not cause clogging even when dust containing oil is sucked, maintains a high air flow rate, and can be used repeatedly.

FIG. 1 is a cross-sectional view of an example of an air filter medium for a vacuum cleaner according to the present invention.

Explanation of symbols

10 Air Filter Media for Vacuum Cleaner Treated with Oil Repellent Treatment 11 PTFE Porous Membrane 12 Support Material

Claims (7)

An air filter medium for vacuum cleaner comprising a polytetrafluoroethylene (PTFE) porous film, wherein the surface of the PTFE porous film is oil repellent. The air filter medium according to claim 1, wherein the oil repellency is imparted by an oil repellency treatment with a fluorine-based oil repellency treatment agent. The air according to claim 2, wherein the fluorine-based oil repellent treatment agent is at least one of an acrylic polymer having a fluorine-containing side chain, a urethane polymer having a fluorine-containing side chain, and a silicone polymer having a fluorine-containing side chain. Filter media. The air filter medium according to claim 2, wherein the fluorine-based oil repellent treatment agent is a treatment agent having a structure represented by the following formula (1).
CH ₃
｜
_{- (C-CH 2) n} -
| (1)
_{CO-C m H 2m -C x} F 2x + 1
‖
O
In the formula (1), n is a positive integer representing the number of repeating units, and m and x are positive integers. The air filter medium according to any one of claims 1 to 4, further comprising a support material. An air filter unit for a vacuum cleaner comprising the air filter medium according to any one of claims 1 to 5. A vacuum cleaner comprising the air filter unit for a vacuum cleaner according to claim 6.

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