JP2005205305A - Air filter medium - Google Patents

Air filter medium Download PDF

Info

Publication number
JP2005205305A
JP2005205305A JP2004014184A JP2004014184A JP2005205305A JP 2005205305 A JP2005205305 A JP 2005205305A JP 2004014184 A JP2004014184 A JP 2004014184A JP 2004014184 A JP2004014184 A JP 2004014184A JP 2005205305 A JP2005205305 A JP 2005205305A
Authority
JP
Japan
Prior art keywords
air filter
filter medium
layer
porous membrane
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2004014184A
Other languages
Japanese (ja)
Inventor
Koji Kouchi
浩二 古内
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority to JP2004014184A priority Critical patent/JP2005205305A/en
Publication of JP2005205305A publication Critical patent/JP2005205305A/en
Pending legal-status Critical Current

Links

Images

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air filter medium which prevents the clogging of a polytetrafluoroethylene (PTFE) porous membrane without increasing the thickness of the membrane in an air filter medium using the PTFE porous membrane. <P>SOLUTION: In the air filter medium 10 which is a laminate of PTFE porous membrane layers 11 and 12, the PTFE porous membrane layer 11 is disposed on the upstream side of air flow (arrow), and the particle collection efficiency for particles with a diameter of 0.3-0.5 μm per 1 μm thickness of the PTFE porous membrane layer 11 is lower than that of the PTFE porous membrane layer 12. Therefore, as the PTFE porous membrane layer having the lowest particle collection efficiency is disposed on the most upstream side of the air flow, large dust can be collected beforehand to prevent the clogging of the PTFE porous membranes. Thereby an increase in pressure loss can be delayed to make the life of the membranes long. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、エアフィルタ濾材に関する。   The present invention relates to an air filter medium.

従来、クリーンルーム等で使用されるエアフィルタユニットには、ガラス繊維にバインダーを加えて抄紙したガラス製エアフィルタ濾材が汎用されている。しかしながら、前記ガラス製エアフィルタ濾材には、その中に付着小繊維が存在し、加工による折り曲げ時に自己発塵するという問題があった。また、自己発塵を防止するためにバインダー量を増加させると、圧力損失が増大してしまうという問題もあった（特許文献１参照。）。   2. Description of the Related Art Conventionally, glass air filter media obtained by making paper by adding a binder to glass fibers have been widely used for air filter units used in clean rooms and the like. However, the glass air filter medium has a problem in that adhering fibrils are present therein, and self-dusting occurs when it is bent by processing. Further, when the amount of the binder is increased in order to prevent self-dusting, there is a problem that the pressure loss increases (see Patent Document 1).

そのため、近年では、クリーンな材料であるポリテトラフルオロエチレン（ＰＴＦＥ）多孔質膜を含むエアフィルタ濾材が様々な分野で使用されている。ＰＴＦＥ多孔質膜は、圧力損失が非常に低く（高通気量で）、捕集効率が非常に高いため、塵埃捕集性能に優れている。しかしながら、ＰＴＦＥ多孔質膜は、粉塵の非常に少ないところでの使用（例えば、クリーンルーム内エアーの循環用フィルタ）では有効だが、ビル空調用やタービン用吸気フィルタ等で大気塵の濾過用に使用した場合、その高捕集効率故に多くの浮遊粒子を取り込んでしまい、その結果、目詰まりを起こして早期に圧力損失が増大してしまうという問題があった。そこで、ＰＴＦＥ多孔質膜より空気の流れの上流側に、プレフィルタ（不織布等の通気性部材）を設けることで、予め大きな粉塵を捕集し、ＰＴＦＥ多孔質膜の目詰まりを防止してエアフィルタ濾材の長寿命化を図る試みがなされている（特許文献２参照）。しかし、プレフィルタを厚くしないと、 ＰＴＦＥの目詰まり防止効果が得られないため、費用と省資源の点で問題があった。また、プレフィルタを厚くすると、プリーツ加工（連続したＷ字状の折り曲げ）が困難になるという問題もあった。
特開昭６３−１６０１９号公報 特開２０００−３００９２１号公報 Therefore, in recent years, air filter media including a polytetrafluoroethylene (PTFE) porous membrane, which is a clean material, has been used in various fields. Since the PTFE porous membrane has a very low pressure loss (with a high air flow rate) and a very high collection efficiency, it has excellent dust collection performance. However, PTFE porous membranes are effective when used in places where there is very little dust (for example, a filter for circulating air in a clean room), but when used for filtering air dust for building air conditioning or turbine intake filters, etc. Because of its high collection efficiency, a large number of suspended particles are taken in. As a result, there is a problem that clogging occurs and pressure loss increases at an early stage. Therefore, by providing a prefilter (breathable member such as non-woven fabric) upstream of the air flow from the PTFE porous membrane, large dust is collected in advance to prevent clogging of the PTFE porous membrane. Attempts have been made to extend the life of filter media (see Patent Document 2). However, if the prefilter is not thickened, the PTFE clogging prevention effect cannot be obtained, and there is a problem in terms of cost and resource saving. Further, when the prefilter is made thick, there is a problem that pleating (continuous W-shaped bending) becomes difficult.
JP-A 63-16019 Japanese Patent Laid-Open No. 2000-300921

そこで、本発明の目的は、ＰＴＦＥ多孔質膜を使用したエアフィルタ濾材であって、厚みを厚くすることなく前記ＰＴＦＥ多孔質膜の目詰まりが防止されたエアフィルタ濾材を提供することである。   Therefore, an object of the present invention is to provide an air filter medium using a PTFE porous membrane, in which clogging of the PTFE porous membrane is prevented without increasing the thickness.

前記目的を達成するために、本発明のエアフィルタ濾材は、ＰＴＦＥ多孔質膜層を２層以上積層した積層フィルタ層を含むエアフィルタ濾材であって、前記積層フィルタ層において、厚み１μｍ当たりの粒子径０．３〜０．５μｍの粒子捕集効率（以下、厚み当たりの粒子捕集効率という。）が異なるＰＴＦＥ多孔質膜層を２層以上含み、前記厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜層が、空気の流れの最上流側に配置されているエアフィルタ濾材である。なお、前記厚み当たりの粒子捕集効率は、後述の方法により測定できる。   In order to achieve the above object, the air filter medium of the present invention is an air filter medium including a laminated filter layer in which two or more PTFE porous membrane layers are laminated, and particles per 1 μm in thickness in the laminated filter layer. It includes two or more PTFE porous membrane layers having a particle collection efficiency of 0.3 to 0.5 μm in diameter (hereinafter referred to as “particle collection efficiency per thickness”) and has the lowest particle collection efficiency per thickness. The PTFE porous membrane layer is an air filter medium disposed on the most upstream side of the air flow. The particle collection efficiency per thickness can be measured by the method described later.

本発明のエアフィルタ濾材では、厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜層が、空気の流れの最上流側に配置されているので、これによって、予め大きな粉塵を捕集でき、この結果、ＰＴＦＥ多孔質膜の目詰まりを防止できる。したがって、本発明のエアフィルタ濾材は、圧力損失の上昇を遅らせることができて長寿命化する。また、別途プレフィルタを設ける場合には、前記積層フィルタ層自体に目詰まり防止効果があるため、従来ほどプレフィルタを厚くする必要がなく、プリーツ加工にも支障がない。なお、本発明のエアフィルタ濾材において、プレフィルタは、任意の構成部材であり、必須の材料ではない。   In the air filter medium of the present invention, since the PTFE porous membrane layer having the lowest particle collection efficiency per thickness is arranged on the most upstream side of the air flow, it is possible to collect large dust in advance, As a result, clogging of the PTFE porous membrane can be prevented. Therefore, the air filter medium of the present invention can delay the increase in pressure loss and prolong the service life. Further, when a prefilter is separately provided, the laminated filter layer itself has an effect of preventing clogging, so that it is not necessary to thicken the prefilter as in the conventional case, and there is no hindrance to pleating. In the air filter medium of the present invention, the prefilter is an arbitrary constituent member and not an essential material.

本発明の積層フィルタ層において、厚み当たりの粒子捕集効率の最も高いＰＴＦＥ多孔質膜層が、空気の流れの最下流側に配置されていることが好ましく、さらに、空気の流れの上流側から下流側に沿って、前記厚み当たりの粒子捕集効率が低い順にＰＴＦＥ多孔質膜層が配置されていることが、より好ましい。   In the multilayer filter layer of the present invention, the PTFE porous membrane layer having the highest particle collection efficiency per thickness is preferably disposed on the most downstream side of the air flow, and further from the upstream side of the air flow. It is more preferable that the PTFE porous membrane layer is arranged along the downstream side in order of increasing particle collection efficiency per thickness.

本発明のエアフィルタ濾材において、前記厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜層の前記厚み当たりの粒子捕集効率が、０．５〜５０％の範囲であることが好ましく、より好ましくは、１〜４０％の範囲である。また、前記厚み当たりの粒子捕集効率の最も高いＰＴＦＥ多孔質膜層の前記厚み当たりの粒子捕集効率が、５〜８０％の範囲であることが好ましく、より好ましくは、１０〜６０％の範囲である。   In the air filter medium of the present invention, the particle collection efficiency per thickness of the PTFE porous membrane layer having the lowest particle collection efficiency per thickness is preferably in the range of 0.5 to 50%, more Preferably, it is 1 to 40% of range. The particle collection efficiency per thickness of the PTFE porous membrane layer having the highest particle collection efficiency per thickness is preferably in the range of 5 to 80%, more preferably 10 to 60%. It is a range.

本発明のエアフィルタ濾材において、さらに、プレフィルタ層を含み、このプレフィルタ層が、前記積層フィルタ層よりも空気の流れの上流側に配置されていることが好ましい。プレフィルタ層の使用により、さらに、ＰＴＦＥ多孔質膜の目詰まりを防止できるからである。   The air filter medium of the present invention preferably further includes a prefilter layer, and this prefilter layer is preferably arranged on the upstream side of the air flow with respect to the laminated filter layer. This is because the use of the prefilter layer can further prevent clogging of the PTFE porous membrane.

本発明のエアフィルタ濾材において、前記プレフィルタ層の厚み当たりの粒子捕集効率が、前記厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜の前記厚み当たりの捕集効率より、低いことが好ましい。さらに、前記プレフィルタ層の前記厚み当たりの粒子捕集効率が、０．０５〜１０％の範囲であることが好ましく、より好ましくは、０．１〜５％の範囲である。   In the air filter medium of the present invention, the particle collection efficiency per thickness of the prefilter layer may be lower than the collection efficiency per thickness of the PTFE porous membrane having the lowest particle collection efficiency per thickness. preferable. Furthermore, the particle collection efficiency per thickness of the prefilter layer is preferably in the range of 0.05 to 10%, and more preferably in the range of 0.1 to 5%.

本発明のエアフィルタ濾材において、前記プレフィルタ層が、繊維性通気性多孔材により形成されていることが好ましい。   In the air filter medium of the present invention, the prefilter layer is preferably formed of a fibrous breathable porous material.

本発明のエアフィルタ濾材において、さらに、通気性保護層を有し、この通気性保護層が、前記積層フィルタ層よりも空気の流れの下流側に配置されていることが好ましい。前記通気性保護層を配置することにより、加工時や使用中に、前記積層フィルタ層の空気の流れの最下流側のＰＴＦＥ多孔質膜層が傷つけられるのを防ぐことができ、さらに、本発明のエアフィルタ濾材の強度を高めることができるからである。   In the air filter medium of the present invention, it is preferable that the air filter medium further has a breathable protective layer, and the breathable protective layer is disposed downstream of the laminated filter layer in the air flow. By disposing the air-permeable protective layer, it is possible to prevent the PTFE porous membrane layer on the most downstream side of the air flow of the multilayer filter layer from being damaged during processing or use. This is because the strength of the air filter medium can be increased.

本発明のエアフィルタ濾材全体において、粒子径０．３〜０．５μｍの粒子の捕集効率が、９９．９７％以上であり、線速５．３ｃｍ／秒における圧力損失が３０〜３００Ｐａの範囲であることが好ましく、より好ましくは、前記捕集効率が９９．９９％以上、圧力損失が５０〜２５０Ｐａの範囲である。なお、前記捕集効率および圧力損失は、後述の方法により測定できる。   In the entire air filter medium of the present invention, the collection efficiency of particles having a particle diameter of 0.3 to 0.5 μm is 99.97% or more, and the pressure loss is 30 to 300 Pa at a linear velocity of 5.3 cm / sec. More preferably, the collection efficiency is 99.99% or more and the pressure loss is in the range of 50 to 250 Pa. The collection efficiency and pressure loss can be measured by the methods described later.

本発明のエアフィルタ濾材全体の厚みは、０．０５〜２．００ｍｍの範囲であることが好ましく、より好ましくは０．１０〜０．６０ｍｍの範囲である。   The thickness of the entire air filter medium of the present invention is preferably in the range of 0.05 to 2.00 mm, more preferably in the range of 0.10 to 0.60 mm.

本発明のエアフィルタ濾材の用途は、特に制限されないが、好ましくは、ビル空調機用エアフィルタ濾材、タービン吸気用エアフィルタ濾材、工場内に外気を取り入れる際の除塵用エアフィルタ濾材、掃除機用エアフィルタ濾材、空気清浄機用エアフィルタ濾材、電気製品用エアフィルタ濾材等である。本発明のエアフィルタユニットは、枠体内にエアフィルタ濾材を配置したエアフィルタユニットであって、前記エアフィルタ濾材が、前記本発明のエアフィルタ濾材である。   The use of the air filter medium of the present invention is not particularly limited, but preferably, an air filter medium for a building air conditioner, an air filter medium for a turbine intake air, a filter medium for dust removal when taking outside air into a factory, and a vacuum cleaner These include air filter media, air filter media for air purifiers, and air filter media for electrical products. The air filter unit of the present invention is an air filter unit in which an air filter medium is disposed in a frame, and the air filter medium is the air filter medium of the present invention.

つぎに、本発明のエアフィルタ濾材について詳しく説明する。   Next, the air filter medium of the present invention will be described in detail.

前述のとおり、本発明のエアフィルタ濾材では、ＰＴＦＥ多孔質膜層を２層以上積層した積層フィルタ層を含み、前記積層フィルタ層において、厚み当たりの粒子捕集効率が異なるＰＴＦＥ多孔質膜層を２層以上含み、前記厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜層が、空気の流れの最上流側に配置されている。   As described above, the air filter medium of the present invention includes a laminated filter layer in which two or more PTFE porous membrane layers are laminated, and in the laminated filter layer, a PTFE porous membrane layer having different particle collection efficiency per thickness is provided. The PTFE porous membrane layer including two or more layers and having the lowest particle collection efficiency per thickness is disposed on the most upstream side of the air flow.

前記積層フィルタ層において、各層の厚さは、それぞれ、例えば、１〜１００μｍの範囲であり、好ましくは２〜５０μｍの範囲であり、より好ましくは３〜３０μｍの範囲である。また、各層の孔径は、それぞれ、例えば、０．１〜１０．０μｍの範囲であり、好ましくは０．３〜８．０μｍの範囲であり、より好ましくは０．５〜５．０μｍの範囲である。また、前記各層の圧力損失は、それぞれ、例えば、５〜２００Ｐａの範囲であり、好ましくは、１０〜１５０Ｐａの範囲である。なお、前記圧力損失は、後述の方法により測定できる。   In the multilayer filter layer, the thickness of each layer is, for example, in the range of 1 to 100 μm, preferably in the range of 2 to 50 μm, and more preferably in the range of 3 to 30 μm. Further, the pore diameter of each layer is, for example, in the range of 0.1 to 10.0 μm, preferably in the range of 0.3 to 8.0 μm, more preferably in the range of 0.5 to 5.0 μm. is there. The pressure loss of each layer is, for example, in the range of 5 to 200 Pa, and preferably in the range of 10 to 150 Pa. The pressure loss can be measured by the method described later.

前記ＰＴＦＥ多孔質膜層の製造方法の一例を以下に示す。すなわち、まず、ＰＴＦＥファインパウダーに液状潤滑剤を加えて、ペースト状の混和物を形成し、それを予備成形する。前記予備成形は、液体潤滑剤が絞り出されない程度の圧力で行う。前記ＰＴＦＥファインパウダーとしては、特に制限されず、市販のものが使用できる。前記液状潤滑剤としては、前記ＰＴＦＥファインパウダーを濡らすことができ、後に除去できるものであれば特に制限されず、例えば、流動パラフィン、ナフサ、ホワイトオイル等の炭化水素油等が使用できる。また、これらは、単独で使用しても良く、若しくは二種類以上併用してもよい。   An example of a method for producing the PTFE porous membrane layer is shown below. That is, first, a liquid lubricant is added to PTFE fine powder to form a paste-like admixture, which is preformed. The preforming is performed at a pressure that does not squeeze out the liquid lubricant. 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 fine powder and can be removed later. For example, hydrocarbon oils such as liquid paraffin, naphtha, and white oil can be used. These may be used singly or in combination of two or more.

前記ＰＴＦＥファインパウダーに対する液状潤滑剤の添加割合は、前記ＰＴＦＥファインパウダーの種類、液状潤滑油の種類および後述するシート成形の条件等により適宜決定されるが、例えば、ＰＴＦＥファインパウダー１００重量部に対して、液状潤滑剤５〜５０重量部の範囲である。   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 5 to 50 parts by weight.

つぎに、前記混和物を未焼成状態でシート状に成形する。前記成形方法としては、例えば、前記混和物をロッド状に押し出した後、対になったロールにより圧延する圧延法や、板状に押し出してシート状にする押し出し法があげられる。また、両方法を組み合わせてもよい。このシート状成形体の厚みは、後に行なう延伸の条件等により適宜決定されるが、例えば、０．１〜０．５ｍｍの範囲である。   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.

なお、得られたシート状成形体に含まれる前記液状潤滑剤は、続いて行なう延伸工程前に、加熱法または抽出法等により除去しておくことが好ましい。前記抽出法に使用する溶媒は、特に制限されないが、例えば、ノルマルデカン、ドデカン、ナフサ、ケロシン、スモイル等があげられる。   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.

つぎに、前記シート状成形体に対して延伸を行なう。前記シート状成形体を一軸延伸または二軸延伸で延伸し多孔化する。例えば、前記シート状成形体の長手方向において、その長さが２〜３０倍の範囲になるように、温度３０〜３２０℃で延伸し、続いて、前記シート状成形体の幅方向において、その長さが２〜３０倍の範囲になるように、温度３０〜３２０℃で延伸する。前記延伸後、その延伸状態を保持して、ＰＴＦＥの融点（３２７℃）以上の温度に加熱して焼成することにより、機械的強度の向上と寸法安定性の増加を図ってもよい。以上のようにして、ＰＴＦＥ多孔質膜が製造できる。このようにして製造されたＰＴＦＥ多孔質膜は、ＰＴＦＥ粒子が繊維化して多孔構造となっている。   Next, it extends | stretches with respect to the said sheet-like molded object. The sheet-like molded body is stretched by uniaxial stretching or biaxial stretching to make it porous. For example, in the longitudinal direction of the sheet-like molded body, it is stretched at a temperature of 30 to 320 ° C. so that its length is in the range of 2 to 30 times, and subsequently in the width direction of the sheet-like molded body, The film is stretched at a temperature of 30 to 320 ° C. so that the length is in the range of 2 to 30 times. After the stretching, the stretched state may be 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. The PTFE porous membrane thus produced has a porous structure in which PTFE particles are fibrillated.

なお、本発明におけるＰＴＦＥ多孔質膜層は、前述の製造方法に制限されず、他の製造方法で製造されてもよい。   In addition, the PTFE porous membrane layer in this invention is not restrict | limited to the above-mentioned manufacturing method, You may manufacture with another manufacturing method.

前記ＰＴＦＥ多孔質膜層の積層方法は、特に制限されないが、例えば、ＰＴＦＥ多孔質膜層を重ね合わせたまま焼成する、接着剤を用いて貼り合わせる等の方法により行うことができる。なお、前記積層フィルタ層において、厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜層を、空気の流れの最上流側に配置する。それ以外のＰＴＦＥ多孔質膜層の配置順は、特に制限されないが、前述の通り、前記厚み当たりの粒子捕集効率の最も高いＰＴＦＥ多孔質膜層が、空気の流れの最下流側に配置されていることが好ましく、さらに、空気の流れの上流側から下流側に沿って、前記厚み当たりの粒子捕集効率が低い順にＰＴＦＥ多孔質膜層が配置されていることが、より好ましい。   The method for laminating the PTFE porous membrane layer is not particularly limited. For example, the PTFE porous membrane layer can be baked with the PTFE porous membrane layers superposed on each other or bonded using an adhesive. In the multilayer filter layer, the PTFE porous membrane layer having the lowest particle collection efficiency per thickness is disposed on the most upstream side of the air flow. The arrangement order of the other PTFE porous membrane layers is not particularly limited. As described above, the PTFE porous membrane layer having the highest particle collection efficiency per thickness is arranged on the most downstream side of the air flow. Furthermore, it is more preferable that the PTFE porous membrane layer is disposed in order from the lowest particle collection efficiency per thickness from the upstream side to the downstream side of the air flow.

前記積層フィルタ層は、ＰＴＦＥ多孔質膜層が直接積層された構造としてもよいし、ＰＴＦＥ多孔質膜層の間に、他の層、例えば、不織布等の通気性部材を挟み込んだ構造としてもよい。   The laminated filter layer may have a structure in which a PTFE porous membrane layer is directly laminated, or a structure in which another layer, for example, a breathable member such as a nonwoven fabric is sandwiched between PTFE porous membrane layers. .

本発明のエアフィルタ濾材は、前述の理由により、必要に応じて、前記積層フィルタ層よりも空気の流れの上流側に、さらに、プレフィルタ層を積層した構造としてもよい。   The air filter medium of the present invention may have a structure in which a prefilter layer is further laminated on the upstream side of the air flow from the laminated filter layer, if necessary, for the reasons described above.

前記プレフィルタ層は、比較的大きな粒子を捕捉する役目のものである。前記プレフィルタ層の形成材料は、特に制限されず、例えば、フェルト、織布、不織布、メッシュ（網目状シート）、その他の多孔質材料等が使用できる。なお、前記プレフィルタ層には、捕集性、作業性の点から不織布を使用することが好ましい。前記プレフィルタ層が繊維材料である場合には、その繊維として、例えば、ポリエチレン、ポリプロピレン等のポリオレフィン、ポリアミド、ポリエステル、芳香族ポリアミド、アクリル、ポリイミド等の合成繊維あるいはこれらの複合材等を用いることができる。   The prefilter layer serves to capture relatively large particles. The material for forming the prefilter layer is not particularly limited, and for example, felt, woven fabric, nonwoven fabric, mesh (mesh-like sheet), other porous materials, and the like can be used. In addition, it is preferable to use a nonwoven fabric for the said pre filter layer from the point of collection property and workability | operativity. When the prefilter layer is a fiber material, for example, a polyolefin such as polyethylene or polypropylene, a synthetic fiber such as polyamide, polyester, aromatic polyamide, acrylic or polyimide, or a composite material thereof is used as the fiber. Can do.

前記プレフィルタ層の厚さは、好ましくは０．０５〜１．００ｍｍの範囲であり、加工性の点から、より好ましくは０．０５〜０．４０ｍｍの範囲である。また、前記プレフィルタ層において、圧力損失が１〜１５０Ｐａの範囲であることが好ましく、より好ましくは、３〜１００Ｐａの範囲である。さらに、前述の通り、前記プレフィルタ層の厚み当たりの粒子捕集効率が、前記厚み当たりの粒子捕集効率が最も低いＰＴＦＥ多孔質膜の前記厚み当たりの捕集効率より、低いことが好ましい。   The thickness of the prefilter layer is preferably in the range of 0.05 to 1.00 mm, and more preferably in the range of 0.05 to 0.40 mm from the viewpoint of workability. In the prefilter layer, the pressure loss is preferably in the range of 1 to 150 Pa, more preferably in the range of 3 to 100 Pa. Furthermore, as described above, the particle collection efficiency per thickness of the prefilter layer is preferably lower than the collection efficiency per thickness of the PTFE porous membrane having the lowest particle collection efficiency per thickness.

前記積層フィルタ層とプレフィルタ層とは、接着して一体化することが好ましい。その接着方法は、特に制限されず、例えば、予め熱接着性をもった通気性部材製のプレフィルタ層をＰＴＦＥ多孔質膜層に熱ラミネートする方法、熱溶融性のネットないしメッシュを間に挟んで前記両層をラミネートする方法、微細な点状ないし線状に接着剤を塗布し接着する方法等があげられる。接着剤としては、２液混合型や熱による自己架橋型の接着剤等を用いることができる。２液混合型としてはエポキシ樹脂、熱による自己架橋型としては酢酸ビニル−エチレン共重合体やエチレン−塩化ビニル共重合体等が好適である。   The laminated filter layer and the prefilter layer are preferably bonded and integrated. The bonding method is not particularly limited. For example, a method of thermally laminating a prefilter layer made of a gas-permeable member having heat adhesion in advance to a PTFE porous membrane layer, or a heat-meltable net or mesh sandwiched therebetween. And a method of laminating the two layers, a method of applying and bonding an adhesive in fine dots or lines, 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.

本発明のエアフィルタ濾材は、前述の理由により、必要に応じて、前記積層フィルタ層よりも空気の流れの下流側に、さらに、通気性保護層を積層した構造としてもよい。前記通気性保護層は、前記プレフィルタ層と同様の材料を使用することができるが、通気性の高いものが好ましい。前記通気保護層と前記積層フィルタ層との接着方法は、前述のプレフィルタ層と積層フィルタ層との接着方法と同様である。通気性保護層の厚さは、例えば、０．０５〜１．００ｍｍの範囲であり、好ましくは０．０５〜０．５０ｍｍの範囲である。また、前記通気性保護層において、圧力損失が１００Ｐａ以下であることが好ましく、より好ましくは、５０Ｐａ以下である。なお、前記圧力損失は、後述の方法により測定できる。   The air filter medium of the present invention may have a structure in which a breathable protective layer is further laminated on the downstream side of the air flow from the laminated filter layer, if necessary, for the reasons described above. The breathable protective layer can be made of the same material as the prefilter layer, but preferably has a high breathability. The method for adhering the air-permeable protective layer and the multilayer filter layer is the same as the method for adhering the prefilter layer and the multilayer filter layer described above. The thickness of the breathable protective layer is, for example, in the range of 0.05 to 1.00 mm, and preferably in the range of 0.05 to 0.50 mm. In the breathable protective layer, the pressure loss is preferably 100 Pa or less, and more preferably 50 Pa or less. The pressure loss can be measured by the method described later.

図１の断面図に、本発明のエアフィルタ濾材の構成の一例を示す。図示のように、このエアフィルタ濾材１０では、ＰＴＦＥ多孔質膜層１１および１２とが積層されており、空気の流れ（矢印）の上流側にＰＴＦＥ多孔質膜層１１が配置されている。ここで、ＰＴＦＥ多孔質膜層１１の厚み当たりの粒子捕集効率は、ＰＴＦＥ多孔質膜層１２の前記厚み当たりの粒子捕集効率より低い。   An example of the structure of the air filter medium of the present invention is shown in the sectional view of FIG. As shown in the figure, in this air filter medium 10, PTFE porous membrane layers 11 and 12 are laminated, and the PTFE porous membrane layer 11 is disposed on the upstream side of the air flow (arrow). Here, the particle collection efficiency per thickness of the PTFE porous membrane layer 11 is lower than the particle collection efficiency per thickness of the PTFE porous membrane layer 12.

図２の断面図に、本発明のエアフィルタ濾材のその他の構成例を示す。図示のように、このエアフィルタ濾材２０では、ＰＴＦＥ多孔質膜層２１および２２よりも空気の流れ（矢印）の上流側に、さらに、プレフィルタ層２３が配置されている。ここで、ＰＴＦＥ多孔質膜層２１の厚み当たりの粒子捕集効率は、ＰＴＦＥ多孔質膜層２２の前記厚み当たりの粒子捕集効率より低い。なお、前記プレフィルタ層２３の材料、厚さ、捕集効率、圧力損失および厚み当たりの粒子捕集効率については、前述のとおりである。   FIG. 2 is a sectional view showing another configuration example of the air filter medium of the present invention. As shown in the figure, in the air filter medium 20, a prefilter layer 23 is further arranged on the upstream side of the air flow (arrow) from the PTFE porous membrane layers 21 and 22. Here, the particle collection efficiency per thickness of the PTFE porous membrane layer 21 is lower than the particle collection efficiency per thickness of the PTFE porous membrane layer 22. The material, thickness, collection efficiency, pressure loss, and particle collection efficiency per thickness of the prefilter layer 23 are as described above.

図３の断面図に、本発明のエアフィルタ濾材のさらにその他の構成例を示す。図示のように、このエアフィルタ濾材３０では、ＰＴＦＥ多孔質膜層３１および３２よりも空気の流れ（矢印）の上流側に、さらに、プレフィルタ層３３が配置され、ＰＴＦＥ多孔質膜層３１および３２よりも空気の流れ（矢印）の下流側に、さらに、通気性保護層３４が配置されている。ここで、ＰＴＦＥ多孔質膜層３１の厚み当たりの粒子捕集効率は、ＰＴＦＥ多孔質膜層３２の前記厚み当たりの粒子捕集効率より低い。なお、前記プレフィルタ層３３の材料、厚さ、捕集効率、圧力損失および厚み当たりの粒子捕集効率については、前述のとおりであり、前記通気性保護層３４の材料、厚さ、捕集効率および圧力損失についても、前述のとおりである。   The sectional view of FIG. 3 shows still another configuration example of the air filter medium of the present invention. As shown in the figure, in this air filter medium 30, a prefilter layer 33 is further disposed upstream of the PTFE porous membrane layers 31 and 32 on the upstream side of the air flow (arrow), and the PTFE porous membrane layer 31 and An air-permeable protective layer 34 is further arranged on the downstream side of the air flow (arrow) from 32. Here, the particle collection efficiency per thickness of the PTFE porous membrane layer 31 is lower than the particle collection efficiency per thickness of the PTFE porous membrane layer 32. The material, thickness, collection efficiency, pressure loss, and particle collection efficiency per thickness of the prefilter layer 33 are as described above, and the material, thickness, and collection of the breathable protective layer 34 are as described above. The efficiency and pressure loss are also as described above.

つぎに、本発明の実施例について、比較例と併せて説明する。なお、実施例および比較例における各特性の測定方法は、以下に示すとおりである。   Next, examples of the present invention will be described together with comparative examples. In addition, the measuring method of each characteristic in an Example and a comparative example is as showing below.

（１）目付け量
ポリプロピレン不織布またはポリエチレン（ＰＥ）／ポリエチレンテレフタレート（ＰＥＴ）の芯鞘構造繊維製の不織布を１００ｃｍ２にサンプリングし、その重さを電子天秤により測定して１ｍ２当たりの質量を求めた。 (1) Weight per unit area A polypropylene nonwoven fabric or a nonwoven fabric made of polyethylene (PE) / polyethylene terephthalate (PET) core-sheath fiber is sampled at 100 cm 2 , and its weight is measured by an electronic balance to determine the mass per 1 m 2. It was.

（２）圧力損失
サンプル（フィルタ層、プレフィルタ層、通気性保護層またはエアフィルタ濾材）を有効面積１００ｃｍ２の円形ホルダーにセットし、入口側から大気塵を供給しつつ、前記入口側と出口側に圧力差を与え、線速（空気の透過速度）を流量計で５．３ｃｍ／秒に調製して前記大気塵を透過させ、圧力損失（単位：Ｐａ）を圧力計（マノメーター）で測定した。なお、前記大気塵とは、雰囲気中に浮遊している塵埃をいう。 (2) Pressure loss A sample (filter layer, pre-filter layer, air-permeable protective layer or 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, the inlet side and the outlet side. A pressure difference is given to the side, the linear velocity (air permeation rate) is adjusted to 5.3 cm / sec with a flow meter to allow the atmospheric dust to pass through, and the pressure loss (unit: Pa) is measured with a pressure meter (manometer). did. The atmospheric dust refers to dust floating in the atmosphere.

（３）捕集効率
捕集効率は、ＪＩＳ Ｋ ３８０３の除菌用空気ろ過デプスフィルタのエアロゾル捕集性能試験方法により、粒子径０．３〜０．５μｍのジオクチルフタレート（ＤＯＰ）の粒子を用いて測定した。捕集効率は、下記式（１）による。また、厚み当たりの粒子捕集効率は、下記式（２）による。
捕集効率（％）＝（１−下流側の粒子数／上流側の粒子数）×１００ （１）
下流側の粒子数の単位：個／リットル
上流側の粒子数の単位：個／リットル (3) 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 the air filter depth filter for sterilization according to JIS K 3803. Measured. The collection efficiency is according to the following formula (1). Moreover, the particle collection efficiency per thickness is based on the following formula (2).
Collection efficiency (%) = (1−the number of particles on the downstream side / the number of particles on the upstream side) × 100 (1)
Unit of the number of particles on the downstream side: pieces / liter Unit of the number of particles on the upstream side: pieces / liter

Figure 2005205305
ａ：膜厚（μｍ）
ｂ：粒子径０．３〜０．５μｍの粒子の捕集効率（％）
図１の構造のエアフィルタ濾材を作製した。すなわち、まず、ＰＴＦＥファインパウダー１００重量部に対して液状潤滑剤（流動パラフィン）３０重量部を均一に混合し、予備成形した。ついで、予備成形物をペースト押出により丸棒状に成形し、圧延した後、ノルマルデカンを用いた抽出法により前記液状潤滑剤を除去し、厚さ０．２ｍｍのシート状ＰＴＦＥ成形体を得た。前記シート状ＰＴＦＥ成形体を、長さが長手方向の２０倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に３０倍になるように１００℃で延伸し、ＰＴＦＥ多孔質膜層１１を得た。前記ＰＴＦＥ多孔質膜層１１の厚さは、５μｍであり、圧力損失は４０Ｐａであった。また、前記ＰＴＦＥ多孔質膜層１１において、捕集効率は８５％であり、厚み当たりの粒子捕集効率は３１．６％であった。つぎに、前記シート状ＰＴＦＥ成形体を、長さが長手方向の１５倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に１５倍になるように３００℃で延伸し、ＰＴＦＥ多孔質膜層１２を得た。前記ＰＴＦＥ多孔質膜層１２の厚さは、１０μｍであり、圧力損失は１５０Ｐａであった。また、前記ＰＴＦＥ多孔質膜層１２において、捕集効率は９９．９８％であり、厚み当たりの粒子捕集効率は５７．３％であった。その後、ＰＴＦＥ多孔質膜層１１とＰＴＦＥ多孔質膜層１２とを、不織布（繊維径２０μｍ、目付け量３０ｇ／ｍ２のＰＥ／ＰＥＴの芯鞘構造繊維製の不織布）を介して積層し、これを１５０℃に加熱した一対のロールの間に通過させることによりラミネートを行い、積層フィルタ層のみから構成されるエアフィルタ濾材１０を得た。作製したエアフィルタ濾材１０の厚さは１９０μｍ、圧力損失は１９０Ｐａ、捕集効率は９９．９９７％であった。
Figure 2005205305
 a: Film thickness (μm)
b: Collection efficiency (%) of particles having a particle diameter of 0.3 to 0.5 μm
An air filter medium having the structure shown in FIG. 1 was produced. That is, first, 30 parts by weight of a liquid lubricant (liquid paraffin) was uniformly mixed with 100 parts by weight of PTFE fine powder and preformed. Subsequently, the preform was formed into a round bar shape by paste extrusion and rolled, and then the liquid lubricant was removed by an extraction method using normal decane to obtain a sheet-like PTFE molded body having a thickness of 0.2 mm. The sheet-like PTFE molded body was stretched at 300 ° C. so that the length was 20 times the longitudinal direction. Then, it extended | stretched at 100 degreeC so that the length might become 30 times in the width direction using the tenter, and the PTFE porous membrane layer 11 was obtained. The thickness of the PTFE porous membrane layer 11 was 5 μm, and the pressure loss was 40 Pa. In the PTFE porous membrane layer 11, the collection efficiency was 85%, and the particle collection efficiency per thickness was 31.6%. Next, the said sheet-like PTFE molded object was extended | stretched at 300 degreeC so that length might be 15 times of a longitudinal direction. Then, it extended | stretched at 300 degreeC so that the length might become 15 times in the width direction using the tenter, and the PTFE porous membrane layer 12 was obtained. The thickness of the PTFE porous membrane layer 12 was 10 μm, and the pressure loss was 150 Pa. In the PTFE porous membrane layer 12, the collection efficiency was 99.98%, and the particle collection efficiency per thickness was 57.3%. Thereafter, the PTFE porous membrane layer 11 and the PTFE porous membrane layer 12 are laminated via a nonwoven fabric (nonwoven fabric made of PE / PET core-sheath fiber with a fiber diameter of 20 μm and a basis weight of 30 g / m 2 ). Was passed between a pair of rolls heated to 150 ° C. to obtain an air filter medium 10 composed only of a laminated filter layer. The produced air filter medium 10 had a thickness of 190 μm, a pressure loss of 190 Pa, and a collection efficiency of 99.997%.

図２の構造のエアフィルタ濾材を作製した。プレフィルタ層２３には、繊維径約５μｍ、厚さ２５０μｍ、目付け量４０ｇ／ｍ２、圧力損失４０Ｐａである市販のポリプロピレン不織布を用いた。前記プレフィルタ層２３において、捕集効率は５５％であり、厚み当たりの粒子捕集効率は０．３％であった。ＰＴＦＥ多孔質膜層２１（実施例１のＰＴＦＥ多孔質膜層１１と同じ）および２２（実施例１のＰＴＦＥ多孔質膜層１２と同じ）の作製方法およびその積層方法は、実施例１と同様とした。ＰＴＦＥ多孔質膜層２１の空気の流れ（矢印）の上流側にプレフィルタ層２３を配置し、前記ＰＴＦＥ多孔質膜層２１と２２との熱ラミネート積層体（実施例１のエアフィルタ濾材１０と同じ）とプレフィルタ層２３とを、不織布（繊維径２０μｍ、目付け量１５ｇ／ｍ２のＰＥ／ＰＥＴの芯鞘構造繊維製の不織布）を介して積層し、これを１５０℃に加熱した一対のロールの間に通過させることによりラミネートを行い、エアフィルタ濾材２０を得た。作製したエアフィルタ濾材２０の厚さは５３０μｍ、圧力損失は２３０Ｐａ、捕集効率は９９．９９８％であった。 An air filter medium having the structure shown in FIG. 2 was produced. For the prefilter layer 23, a commercially available polypropylene nonwoven fabric having a fiber diameter of about 5 μm, a thickness of 250 μm, a basis weight of 40 g / m 2 , and a pressure loss of 40 Pa was used. In the prefilter layer 23, the collection efficiency was 55%, and the particle collection efficiency per thickness was 0.3%. The production method of PTFE porous membrane layer 21 (same as PTFE porous membrane layer 11 of Example 1) and 22 (same as PTFE porous membrane layer 12 of Example 1) and the lamination method thereof are the same as in Example 1. It was. A pre-filter layer 23 is disposed on the upstream side of the air flow (arrow) of the PTFE porous membrane layer 21, and a thermal laminate laminate of the PTFE porous membrane layers 21 and 22 (the air filter medium 10 of Example 1) The same) and the prefilter layer 23 are laminated via a non-woven fabric (non-woven fabric made of PE / PET core-sheath fiber with a fiber diameter of 20 μm and a basis weight of 15 g / m 2 ), and this is heated to 150 ° C. Lamination was performed by passing between rolls to obtain an air filter medium 20. The produced air filter medium 20 had a thickness of 530 μm, a pressure loss of 230 Pa, and a collection efficiency of 99.998%.

実施例１と同様にして、シート状ＰＴＦＥ成形体を作製した。これを、長さが長手方向の２５倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に３５倍になるように１００℃で延伸し、ＰＴＦＥ多孔質膜層４１を得た。前記ＰＴＦＥ多孔質膜層４１の厚さは、４μｍであり、圧力損失は３０Ｐａであった。また、前記ＰＴＦＥ多孔質膜層４１において、捕集効率は７０％であり、厚み当たりの粒子捕集効率は２６％であった。つぎに、前記シート状ＰＴＦＥ成形体を、長さが長手方向の２０倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に３０倍になるように３００℃で延伸し、ＰＴＦＥ多孔質膜層４２を得た。前記ＰＴＦＥ多孔質膜層４２の厚さは、５μｍであり、圧力損失は４０Ｐａであった。また、前記ＰＴＦＥ多孔質膜層４２において、捕集効率は８５％であり、厚み当たりの粒子捕集効率は３１．６％であった。さらに、前記シート状ＰＴＦＥ成形体を、長さが長手方向の２０倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に２０倍になるように３００℃で延伸し、ＰＴＦＥ多孔質膜層４３を得た。前記ＰＴＦＥ多孔質膜層４３の厚さは、１０μｍであり、圧力損失は９０Ｐａであった。また、前記ＰＴＦＥ多孔質膜層４３において、捕集効率は９９．９％であり、厚み当たりの粒子捕集効率は４９．９％であった。ＰＴＦＥ多孔質膜層４２を中心に、ＰＴＦＥ多孔質膜層４２の空気の流れの上流側にＰＴＦＥ多孔質膜層４１を、空気の流れの下流側にＰＴＦＥ多孔質膜層４３を配置し、前記ＰＴＦＥ多孔質膜層４２とＰＴＦＥ多孔質膜層４１および４３とを、不織布（繊維径２０μｍ、目付け量１５ｇ／ｍ２のＰＥ／ＰＥＴの芯鞘構造繊維製の不織布）を介して積層し、これを１５０℃に加熱した一対のロールの間に通過させることによりラミネートを行い、エアフィルタ濾材（図示せず）を得た。作製したエアフィルタ濾材の厚さは２００μｍ、圧力損失は１６０Ｐａ、捕集効率は９９．９９６％であった。
（比較例１）
実施例１と同様にして、シート状ＰＴＦＥ成形体を作製した。これを、長さが長手方向の１３倍になるように３００℃で延伸を行った。続いて、テンターを用いてその長さが幅方向に１５倍になるように１００℃で延伸し、ＰＴＦＥ多孔質膜層５１を得た。前記ＰＴＦＥ多孔質膜層５１の厚さは、１０μｍであり、圧力損失は２００Ｐａであった。また、前記ＰＴＦＥ多孔質膜層５１において、捕集効率は９９．９９８％であり、厚み当たりの粒子捕集効率は５７．３％であった。ＰＴＦＥ多孔質膜層５１の空気の流れの下流側に通気性保護層５２（繊維径２０μｍ、目付け量３０ｇ／ｍ２のＰＥ／ＰＥＴの芯鞘構造繊維製の不織布）を配置し、これを１５０℃に加熱した一対のロールの間に通過させることによりラミネートを行い、熱ラミネート積層体（図示せず）を得た。作製した熱ラミネート積層体の厚さは１９０μｍ、圧力損失は２００Ｐａ、捕集効率は９９．９９８％であった。この熱ラミネート積層体を、エアフィルタ濾材として用いた。
（比較例２）
ＰＴＦＥ多孔質膜層２１と２２の配列順を逆にしたこと以外は実施例２と同様にしてエアフィルタ濾材（厚み当たりの粒子捕集効率の高いＰＴＦＥ多孔質膜層２２が空気の流れの上流側に配置されたエアフィルタ濾材）を得た。このエアフィルタ濾材の厚さは５３０μｍ、圧力損失は２３０Ｐａ、捕集効率は９９．９９８％であった。 A sheet-like PTFE molded body was produced in the same manner as in Example 1. This was stretched at 300 ° C. so that the length was 25 times the longitudinal direction. Then, it extended | stretched at 100 degreeC so that the length might become 35 times in the width direction using the tenter, and the PTFE porous membrane layer 41 was obtained. The thickness of the PTFE porous membrane layer 41 was 4 μm, and the pressure loss was 30 Pa. In the PTFE porous membrane layer 41, the collection efficiency was 70%, and the particle collection efficiency per thickness was 26%. Next, the sheet-like PTFE molded body was stretched at 300 ° C. so that the length was 20 times the longitudinal direction. Then, it extended | stretched at 300 degreeC so that the length might become 30 times in the width direction using the tenter, and the PTFE porous membrane layer 42 was obtained. The thickness of the PTFE porous membrane layer 42 was 5 μm, and the pressure loss was 40 Pa. In the PTFE porous membrane layer 42, the collection efficiency was 85%, and the particle collection efficiency per thickness was 31.6%. Furthermore, the said sheet-like PTFE molded object was extended | stretched at 300 degreeC so that length might be 20 times the longitudinal direction. Then, it extended | stretched at 300 degreeC so that the length might become 20 times in the width direction using the tenter, and the PTFE porous membrane layer 43 was obtained. The thickness of the PTFE porous membrane layer 43 was 10 μm, and the pressure loss was 90 Pa. In the PTFE porous membrane layer 43, the collection efficiency was 99.9%, and the particle collection efficiency per thickness was 49.9%. Centering on the PTFE porous membrane layer 42, the PTFE porous membrane layer 41 is disposed on the upstream side of the air flow of the PTFE porous membrane layer 42, and the PTFE porous membrane layer 43 is disposed on the downstream side of the air flow. The PTFE porous membrane layer 42 and the PTFE porous membrane layers 41 and 43 are laminated via a nonwoven fabric (nonwoven fabric made of PE / PET core-sheath fiber with a fiber diameter of 20 μm and a basis weight of 15 g / m 2 ). Was passed between a pair of rolls heated to 150 ° C. to obtain an air filter medium (not shown). The produced air filter medium had a thickness of 200 μm, a pressure loss of 160 Pa, and a collection efficiency of 99.996%.
(Comparative Example 1)
A sheet-like PTFE molded body was produced in the same manner as in Example 1. This was stretched at 300 ° C. so that the length was 13 times the longitudinal direction. Then, it extended | stretched at 100 degreeC so that the length might become 15 times in the width direction using the tenter, and the PTFE porous membrane layer 51 was obtained. The thickness of the PTFE porous membrane layer 51 was 10 μm, and the pressure loss was 200 Pa. In the PTFE porous membrane layer 51, the collection efficiency was 99.998%, and the particle collection efficiency per thickness was 57.3%. A breathable protective layer 52 (nonwoven fabric made of PE / PET core-sheath fiber with a fiber diameter of 20 μm and a basis weight of 30 g / m 2 ) is disposed on the downstream side of the air flow of the PTFE porous membrane layer 51. Lamination was performed by passing between a pair of rolls heated to ° C. to obtain a thermal laminate laminate (not shown). The thickness of the produced heat laminate was 190 μm, the pressure loss was 200 Pa, and the collection efficiency was 99.998%. This heat laminate laminate was used as an air filter medium.
(Comparative Example 2)
Except that the arrangement order of the PTFE porous membrane layers 21 and 22 is reversed, the air filter medium (the PTFE porous membrane layer 22 having a high particle collection efficiency per thickness is upstream of the air flow) in the same manner as in Example 2. Air filter medium arranged on the side) was obtained. The thickness of the air filter medium was 530 μm, the pressure loss was 230 Pa, and the collection efficiency was 99.998%.

このようにして得られた実施例１〜３、および比較例１、２のエアフィルタ濾材について、前述の方法により、経時的な圧力損失の変化を調べた。その結果を図４、５に示す。図４に示すように、実施例１のエアフィルタ濾材は１５時間を過ぎても、実施例３のエアフィルタ濾材は２５時間を過ぎても圧力損失がほとんど上昇しなかった。これに対し、比較例１では、１０時間前から急激に圧力損失が上昇した。また、図５に示すように、プレフィルタ層を設けた実施例２のエアフィルタ濾材は、１２０時間を過ぎても圧力損失がほとんど上昇しなかった。これに対し、同じくプレフィルタ層を設けた比較例２では、６０時間を過ぎる前から圧力損失が上昇した。   The air filter media of Examples 1 to 3 and Comparative Examples 1 and 2 thus obtained were examined for changes in pressure loss over time by the method described above. The results are shown in FIGS. As shown in FIG. 4, even when the air filter medium of Example 1 passed 15 hours and the air filter medium of Example 3 passed 25 hours, the pressure loss hardly increased. On the other hand, in Comparative Example 1, the pressure loss increased rapidly from 10 hours ago. Further, as shown in FIG. 5, the pressure loss of the air filter medium of Example 2 provided with the prefilter layer hardly increased even after 120 hours. On the other hand, in Comparative Example 2 in which the prefilter layer was similarly provided, the pressure loss increased before 60 hours passed.

本発明のエアフィルタ濾材は、例えば、ビル空調機用エアフィルタ濾材、タービン吸気用エアフィルタ濾材、工場内に外気を取り入れる際の除塵用エアフィルタ濾材、掃除機用エアフィルタ濾材、空気清浄機用エアフィルタ濾材、電気製品用エアフィルタ濾材等として利用可能である。   The air filter medium of the present invention includes, for example, an air filter medium for a building air conditioner, an air filter medium for a turbine intake air, a dust filter air filter medium for taking outside air into a factory, an air filter medium for a vacuum cleaner, and an air cleaner. It can be used as an air filter medium, an air filter medium for electrical products, and the like.

本発明におけるエアフィルタ濾材の構成の一例の断面図である。It is sectional drawing of an example of a structure of the air filter medium in this invention. 本発明におけるエアフィルタ濾材のその他の構成例の断面図である。It is sectional drawing of the other structural example of the air filter medium in this invention. 本発明におけるエアフィルタ濾材のさらにその他の構成例の断面図である。It is sectional drawing of the further another structural example of the air filter medium in this invention. 本発明の一実施例における圧力損失の経時変化を示すグラフである。It is a graph which shows a time-dependent change of the pressure loss in one Example of this invention. 本発明のその他の実施例における圧力損失の経時変化を示すグラフである。It is a graph which shows the time-dependent change of the pressure loss in the other Example of this invention.

符号の説明Explanation of symbols

１０、２０、３０ エアフィルタ濾材
１１、１２、２１、２２、３１、３２ ＰＴＦＥ多孔質膜層
２３、３３ プレフィルタ層
３４ 通気性保護層 10, 20, 30 Air filter medium 11, 12, 21, 22, 31, 32 PTFE porous membrane layer 23, 33 Prefilter layer 34 Breathable protective layer

Claims (11)

ポリテトラフルオロエチレン（ＰＴＦＥ）多孔質膜層を２層以上積層した積層フィルタ層を含むエアフィルタ濾材であって、前記積層フィルタ層において、厚み１μｍ当たりの粒子径０．３〜０．５μｍの粒子捕集効率が異なるＰＴＦＥ多孔質膜層を２層以上含み、前記粒子捕集効率が最も低いＰＴＦＥ多孔質膜層が、空気の流れの最上流側に配置されていることを特徴とするエアフィルタ濾材。 An air filter medium including a laminated filter layer in which two or more porous layers of polytetrafluoroethylene (PTFE) are laminated, wherein particles having a particle diameter of 0.3 to 0.5 µm per 1 µm thickness in the laminated filter layer An air filter comprising two or more PTFE porous membrane layers having different collection efficiencies, wherein the PTFE porous membrane layer having the lowest particle collection efficiency is disposed on the most upstream side of the air flow Filter media. 前記積層フィルタ層において、前記粒子捕集効率の最も高いＰＴＦＥ多孔質膜層が、空気の流れの最下流側に配置されている請求項１記載のエアフィルタ濾材。 The air filter medium according to claim 1, wherein in the multilayer filter layer, the PTFE porous membrane layer having the highest particle collection efficiency is disposed on the most downstream side of the air flow. 前記積層フィルタ層において、空気の流れの上流側から下流側に沿って、前記粒子捕集効率が低い順にＰＴＦＥ多孔質膜層が配置されている請求項１または２記載のエアフィルタ濾材。 3. The air filter medium according to claim 1, wherein in the laminated filter layer, the PTFE porous membrane layer is disposed in order of decreasing particle collection efficiency from the upstream side to the downstream side of the air flow. さらに、プレフィルタ層を含み、このプレフィルタ層が、前記積層フィルタ層よりも空気の流れの上流側に配置されている請求項１から３のいずれかに記載のエアフィルタ濾材。 The air filter medium according to any one of claims 1 to 3, further comprising a prefilter layer, wherein the prefilter layer is disposed upstream of the laminated filter layer in the air flow. 前記プレフィルタ層の厚み１μｍ当たりの粒子径０．３〜０．５μｍの粒子捕集効率が、前記粒子捕集効率が最も低いＰＴＦＥ多孔質膜層の前記粒子捕集効率より、低い請求項４記載のエアフィルタ濾材。 5. The particle collection efficiency of a particle diameter of 0.3 to 0.5 μm per 1 μm thickness of the prefilter layer is lower than the particle collection efficiency of the PTFE porous membrane layer having the lowest particle collection efficiency. The air filter medium described. 前記プレフィルタ層が、繊維性通気性多孔材により形成されている請求項４または５記載のエアフィルタ濾材。 The air filter medium according to claim 4 or 5, wherein the prefilter layer is formed of a fibrous breathable porous material. さらに、通気性保護層を有し、この通気性保護層が、前記積層フィルタ層よりも空気の流れの下流側に配置されている請求項１から６のいずれかに記載のエアフィルタ濾材。 The air filter medium according to any one of claims 1 to 6, further comprising a breathable protective layer, and the breathable protective layer is disposed downstream of the laminated filter layer in the air flow. エアフィルタ濾材全体において、粒子径０．３〜０．５μｍの粒子捕集効率が９９．９７％以上であり、線速５．３ｃｍ／秒における圧力損失が３０〜３００Ｐａの範囲である請求項１から７のいずれかに記載のエアフィルタ濾材。 2. The air filter medium as a whole has a particle collection efficiency of 99.97% or more with a particle size of 0.3 to 0.5 μm and a pressure loss in the range of 30 to 300 Pa at a linear velocity of 5.3 cm / sec. The air filter medium in any one of 7 to 7. エアフィルタ濾材全体の厚みが、０．０５〜２．００ｍｍの範囲である請求項１から８のいずれかに記載のエアフィルタ濾材。 The air filter medium according to any one of claims 1 to 8, wherein the entire thickness of the air filter medium is in the range of 0.05 to 2.00 mm. その用途が、ビル空調機用エアフィルタ濾材、タービン吸気用エアフィルタ濾材、工場内に外気を取り入れる際の除塵用エアフィルタ濾材、掃除機用エアフィルタ濾材、空気清浄機用エアフィルタおよび電気製品用エアフィルタ濾材からなる群から選択される少なくとも一つの用途である請求項１から９のいずれかに記載のエアフィルタ濾材。 Applications include air filter media for building air conditioners, air filter media for turbine intake, air filter media for dust removal when taking outside air into the factory, air filter media for vacuum cleaners, air filters for air purifiers, and electrical products The air filter medium according to any one of claims 1 to 9, which is at least one application selected from the group consisting of air filter medium. 枠体内にエアフィルタ濾材を配置したエアフィルタユニットであって、前記エアフィルタ濾材が、請求項１から１０のいずれかに記載のエアフィルタ濾材であるエアフィルタユニット。

11. An air filter unit in which an air filter medium is disposed in a frame, wherein the air filter medium is the air filter medium according to claim 1.

JP2004014184A 2004-01-22 2004-01-22 Air filter medium Pending JP2005205305A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2004014184A JP2005205305A (en) 2004-01-22 2004-01-22 Air filter medium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2004014184A JP2005205305A (en) 2004-01-22 2004-01-22 Air filter medium

Publications (1)

Publication Number Publication Date
JP2005205305A true JP2005205305A (en) 2005-08-04

Family

ID=34900047

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2004014184A Pending JP2005205305A (en) 2004-01-22 2004-01-22 Air filter medium

Country Status (1)

Country Link
JP (1) JP2005205305A (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006061830A (en) * 2004-08-26 2006-03-09 Nitto Denko Corp Air filter medium for domestic electric appliance
WO2010052976A1 (en) 2008-11-04 2010-05-14 日東電工株式会社 Polytetrafluoroethylene porous membrane, method for producing same and waterproof air-permeable filter
JP2010528844A (en) * 2007-06-08 2010-08-26 ゴア エンタープライズ ホールディングス，インコーポレイティド Multilayer filter media
JP2012020274A (en) * 2010-06-17 2012-02-02 Daikin Industries Ltd Filtering material having porous film, manufacturing method for the filtering material, filter pack, and filter unit
WO2017154980A1 (en) * 2016-03-11 2017-09-14 ダイキン工業株式会社 Filter medium for air filters, filter pack, air filter unit, and manufacturing method for filter medium for air filters
WO2018062113A1 (en) * 2016-09-30 2018-04-05 日東電工株式会社 Air filter material, air filter pack, and air filter unit
WO2018131573A1 (en) * 2017-01-12 2018-07-19 ダイキン工業株式会社 Air filter medium
WO2020204177A1 (en) * 2019-04-04 2020-10-08 日東電工株式会社 Filtering material and filter unit
CN114132032A (en) * 2021-11-24 2022-03-04 西南林业大学 Air filtering membrane with adsorbability and preparation method thereof
EP3804832A4 (en) * 2018-06-01 2022-03-16 Nitto Denko Corporation Filter medium and filter unit including same

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09206568A (en) * 1996-02-01 1997-08-12 Nitto Denko Corp Material for air filter
JP2000079332A (en) * 1998-07-08 2000-03-21 Nitto Denko Corp Filter medium for air filter
JP2000300921A (en) * 1999-04-21 2000-10-31 Nitto Denko Corp Air filter material and air filter unit using the same
JP2001170461A (en) * 1999-10-07 2001-06-26 Daikin Ind Ltd Air filter medium, air filter pack and air filter unit using the same, and method for manufacturing air filter medium
JP2001170424A (en) * 1999-12-20 2001-06-26 Nitto Denko Corp Filter material for air filter and air filter unit using the same
JP2002346319A (en) * 2001-05-21 2002-12-03 Nitto Denko Corp Suction filter medium for turbine
JP2002370020A (en) * 2001-06-13 2002-12-24 Nitto Denko Corp Suction filter medium for turbine, its using method and manufacturing method therefor

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09206568A (en) * 1996-02-01 1997-08-12 Nitto Denko Corp Material for air filter
JP2000079332A (en) * 1998-07-08 2000-03-21 Nitto Denko Corp Filter medium for air filter
JP2000300921A (en) * 1999-04-21 2000-10-31 Nitto Denko Corp Air filter material and air filter unit using the same
JP2001170461A (en) * 1999-10-07 2001-06-26 Daikin Ind Ltd Air filter medium, air filter pack and air filter unit using the same, and method for manufacturing air filter medium
JP2001170424A (en) * 1999-12-20 2001-06-26 Nitto Denko Corp Filter material for air filter and air filter unit using the same
JP2002346319A (en) * 2001-05-21 2002-12-03 Nitto Denko Corp Suction filter medium for turbine
JP2002370020A (en) * 2001-06-13 2002-12-24 Nitto Denko Corp Suction filter medium for turbine, its using method and manufacturing method therefor

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006061830A (en) * 2004-08-26 2006-03-09 Nitto Denko Corp Air filter medium for domestic electric appliance
JP2010528844A (en) * 2007-06-08 2010-08-26 ゴア エンタープライズ ホールディングス，インコーポレイティド Multilayer filter media
WO2010052976A1 (en) 2008-11-04 2010-05-14 日東電工株式会社 Polytetrafluoroethylene porous membrane, method for producing same and waterproof air-permeable filter
US8449660B2 (en) 2008-11-04 2013-05-28 Nitto Denko Corporation Polytetrafluoroethylene porous membrane, method for producing same, and waterproof air-permeable filter
JP2012020274A (en) * 2010-06-17 2012-02-02 Daikin Industries Ltd Filtering material having porous film, manufacturing method for the filtering material, filter pack, and filter unit
US10537836B2 (en) 2016-03-11 2020-01-21 Daikin Industries, Ltd. Filter medium for air filter, filter pack, air filter unit and method for producing the filter medium for air filter
WO2017154980A1 (en) * 2016-03-11 2017-09-14 ダイキン工業株式会社 Filter medium for air filters, filter pack, air filter unit, and manufacturing method for filter medium for air filters
JP2017159281A (en) * 2016-03-11 2017-09-14 ダイキン工業株式会社 Filter medium for air filter, filter pack, air filter unit, and manufacturing method of the filter medium for air filter
US11213782B2 (en) 2016-09-30 2022-01-04 Nitto Denko Corporation Air filter medium, air filter pack, and air filter unit
WO2018062113A1 (en) * 2016-09-30 2018-04-05 日東電工株式会社 Air filter material, air filter pack, and air filter unit
WO2018131573A1 (en) * 2017-01-12 2018-07-19 ダイキン工業株式会社 Air filter medium
JP2018111077A (en) * 2017-01-12 2018-07-19 ダイキン工業株式会社 Filter medium for air filter
US11426690B2 (en) 2017-01-12 2022-08-30 Daikin Industries, Ltd. Air filter medium
EP3804832A4 (en) * 2018-06-01 2022-03-16 Nitto Denko Corporation Filter medium and filter unit including same
JP7356971B2 (en) 2018-06-01 2023-10-05 日東電工株式会社 Filter medium and filter unit equipped with the same
CN113677424A (en) * 2019-04-04 2021-11-19 日东电工株式会社 Filter medium and filter unit
WO2020204177A1 (en) * 2019-04-04 2020-10-08 日東電工株式会社 Filtering material and filter unit
EP3950105A4 (en) * 2019-04-04 2022-12-14 Nitto Denko Corporation Filtering material and filter unit
JP7405837B2 (en) 2019-04-04 2023-12-26 日東電工株式会社 Filter media and filter unit
CN114132032A (en) * 2021-11-24 2022-03-04 西南林业大学 Air filtering membrane with adsorbability and preparation method thereof
CN114132032B (en) * 2021-11-24 2024-03-08 西南林业大学 Air filtering membrane with adsorptivity and preparation method thereof

Similar Documents

Publication Publication Date Title
CA2999397C (en) Air filter medium, air filter pack, and air filter unit
EP3520874B1 (en) Air filter medium, air filter pack, and air filter unit
JP5784458B2 (en) Air filter media
EP3520873B1 (en) Air filter medium, air filter pack, and air filter unit
JP6292920B2 (en) Air filter medium manufacturing method, air filter medium and air filter pack
KR100985515B1 (en) Multi-layered gas media for air cleaning
JP2000300921A (en) Air filter material and air filter unit using the same
TWI750230B (en) Air filter media, air filter group and air filter unit
JP2005177641A (en) Air filter unit, its manufacturing method and its assembly
JP2008055407A (en) Method for manufacturing polytetrafluoroethylene porous film and air filter filtering medium
JP3761172B2 (en) Filter material for air filter, method of using the same, air filter unit and air-permeable support material
JP2005205305A (en) Air filter medium
JP2002370020A (en) Suction filter medium for turbine, its using method and manufacturing method therefor
JP2001170424A (en) Filter material for air filter and air filter unit using the same
JP2002346319A (en) Suction filter medium for turbine
JP2005169167A (en) Air filter filtering medium
WO2019230983A1 (en) Filter medium and filter unit including same
JP2005095803A (en) Filter medium for air filter, and air filter unit using it
JP2005246233A (en) Air filter medium for cleaner, and air filter unit for cleaner using the same
JPH10211409A (en) Filter media for air filter and air filter
JP2006061808A (en) Ventilation filter medium for masks
JP2008279359A (en) Filter medium and filter unit using this filter medium
JP2002370009A (en) Suction filter medium for turbine and use method therefor
CN113272038B (en) Filter pleat pack and air filter unit
WO2020204177A1 (en) Filtering material and filter unit

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20061106

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20080617

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20091001

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20100302