WO2004006622A1 - Process for producing heat-resistant electret material and electrostatic acoustic sensor comprising the material - Google Patents

Process for producing heat-resistant electret material and electrostatic acoustic sensor comprising the material Download PDF

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Publication number
WO2004006622A1
WO2004006622A1 PCT/JP2003/008396 JP0308396W WO2004006622A1 WO 2004006622 A1 WO2004006622 A1 WO 2004006622A1 JP 0308396 W JP0308396 W JP 0308396W WO 2004006622 A1 WO2004006622 A1 WO 2004006622A1
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WO
WIPO (PCT)
Prior art keywords
heat
fluororesin
resistant electret
electret
porous sheet
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PCT/JP2003/008396
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French (fr)
Japanese (ja)
Inventor
Susumu Kawato
Original Assignee
Toho Kasei Co., Ltd.
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Publication date
Application filed by Toho Kasei Co., Ltd. filed Critical Toho Kasei Co., Ltd.
Publication of WO2004006622A1 publication Critical patent/WO2004006622A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/04—Microphones
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G7/00—Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture
    • H01G7/02—Electrets, i.e. having a permanently-polarised dielectric
    • H01G7/021—Electrets, i.e. having a permanently-polarised dielectric having an organic dielectric

Definitions

  • the present invention relates to an electret material used for an earphone, a headphone, a microphone, or the like, an electret using the same, a method of manufacturing the same, and an electrostatic acoustic sensor.
  • thermoplastic resin film capable of forming an electret is laminated on a metal sheet and the resin is electretized.
  • a method of forming a thin film by applying an organic solvent in which fine particles of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) are dispersed to a metal plate, and forming the thin film into an electret Also, a method of spraying a metal plate with a spray liquid in which fine particles of FEP are dispersed, followed by firing to form an electret (see Japanese Patent Application Laid-Open No. 2000-15095). See Japanese Patent Application Laid-Open No. 11-89595.
  • the present invention provides a heat-resistant electret material, which is a porous sheet containing a fluororesin, wherein the porous sheet has a porosity of 15 to 80%.
  • the present invention also provides a heat-resistant electret comprising a metal sheet and a porous sheet disposed on a surface thereof, wherein the porous sheet contains a fluororesin, and the porosity of the porous sheet is 15 to 80. % Heat-resistant electret.
  • the present invention is a method for producing a heat-resistant electret in which a porous sheet is attached to a surface of a metal plate, wherein the porous sheet contains a fluororesin, and the porosity of the porous sheet is 15 to 80. %, And a method for producing a heat-resistant electret, characterized in that:
  • the present invention is a heat-resistant electret material obtained by laminating a porous sheet containing a fluororesin and a film containing a fluororesin, wherein the porous sheet has a porosity of 15 to 80%.
  • a heat-resistant material for electrets Disclosed is a heat-resistant material for electrets.
  • the present invention is a heat-resistant electret in which a heat-resistant electret material is disposed on a surface of a metal plate, wherein the heat-resistant electret material is a porous sheet containing a fluororesin, and a film containing a fluororesin.
  • a heat-resistant electret which is laminated and has a porosity of 15 to 80%.
  • the present invention also provides a method for producing a heat-resistant electret, which comprises bonding a heat-resistant electret material to a surface of a metal plate, A heat-resistant material comprising a porous sheet containing a fluororesin and a film containing a fluororesin, wherein the porosity of the porous sheet is 15 to 80%.
  • a heat-resistant material comprising a porous sheet containing a fluororesin and a film containing a fluororesin, wherein the porosity of the porous sheet is 15 to 80%.
  • the present invention provides a method of coating a porous resin layer containing a fluorine resin on the surface of the metal plate by coating the surface of the metal plate with a resin composition containing the fluorine resin and then foaming the resin composition.
  • a method for manufacturing a heat-resistant electret which is characterized by being formed.
  • the present invention provides a method for coating the surface of a metal plate with a resin composition containing a fluororesin and an additional resin that decomposes at a lower temperature than the fluororesin, and then firing the resin composition to form the additional resin.
  • a method for producing a heat-resistant electret which comprises decomposing and removing a porous resin layer containing a fluororesin on the surface of the metal plate.
  • the present invention provides a method for coating a surface of a metal plate with a fluorine-containing resin by coating the surface with a resin composition containing a powdery fluororesin to form voids, and then firing the resin composition.
  • a method for manufacturing a heat-resistant electret which comprises forming a porous resin layer containing a resin.
  • the present invention also provides an electrostatic acoustic sensor including the heat-resistant electret described above.
  • FIG. 1 is a cross-sectional view of the electret manufactured in Example 1.
  • FIG. 2 is a diagram showing the relationship between the residual ratio of the surface potential of the electret and the temperature.
  • the heat-resistant electret material of the present invention is a porous sheet containing a fluororesin.
  • the porous sheet is characterized in that the porosity of the porous sheet is 15 to 80%, more preferably 50 to 80%.
  • fluororesin is a resin with high heat resistance, and by using a porous fluororesin sheet with a porosity of 15 to 80% as the material for electrets, the decrease in the surface potential of the electret at high temperatures is suppressed.
  • the heat resistance of the electret can be improved.
  • the porosity is less than 15%, the surface potential of the electret at a high temperature may decrease significantly, and if the porosity exceeds 80%, it becomes difficult to prepare a sheet as an electret material.
  • the melting point of polytetrafluoroethylene (PTFE), which is a typical fluororesin, is about 327.
  • PTFE polytetrafluoroethylene
  • a microphone or the like can be manufactured by using the MEMS (Micro Electro t MeCh a n Si c Sy s tems) technology at which the heating temperature becomes about 300.
  • a film containing a fluororesin may be further bonded to the porous sheet. This makes it possible to smooth the surface of the electret, and does not hinder the operation of the diaphragm when the electret is used for a microphone or the like.
  • the fluororesin is preferably polytetrafluoroethylene (PTF E), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene, It is preferably at least one selected from the group consisting of ethylene-hexafluoropropylene copolymer (F EP) and tetrafluoroethylene-perfluoromethylvinyl ether (MFA).
  • the dielectric constant and volume resistivity of the porous sheet are 2.1 or less and 1.0 X 10 16 Qcm or more, respectively.
  • the heat-resistant electret of the present invention is characterized in that the heat-resistant electret material is disposed on a surface of a metal plate. As a result, an electret having excellent heat resistance can be provided.
  • the thickness of the porous sheet is not particularly limited, but is usually 5 to 400 m, preferably 10 to 50 m. Within this range, the electret can be made thinner and smaller while maintaining the characteristics of the electret. Further, as the form of the porous sheet, a nonwoven fabric, a woven fabric, a paper, a stretched film, an unsintered tape, or the like can be used.
  • the metal plate may be made of brass, aluminum, stainless steel, copper, titanium, nickel silver, phosphor bronze, an alloy thereof, a metal plated with the metal, and a metal on which the metal is deposited. It is preferably formed from at least one selected from the group consisting of This is because these metals are excellent in corrosion resistance, electrical conductivity, and workability.
  • a metal plate free of oils and fats it is preferable to perform a base treatment to improve the adhesiveness to the sheet.
  • the underlayer treatment includes, for example, formation of a film by anodic oxidation or chemical conversion treatment, use of a coupling agent, and other methods for improving adhesion.
  • the method for producing a heat-resistant electret of the present invention is characterized in that the above-mentioned heat-resistant electret material is bonded to a surface of a metal plate. That is, for example, a porous sheet containing a fluororesin having a porosity of 15 to 80% is prepared, and a metal sheet is provided on the side of the heating roll in a pressing roll composed of a pair of a heating roll and a roll having no heating source. The metal plate and the porous sheet are inserted between the pressure rolls while supplying the plate and supplying the porous sheet to the nozzle side having no heating source. By controlling the contact time with the porous sheet to 1 to 3 seconds and the contact band width to 1 to 20 mm, the metal plate and the porous sheet can be thermocompression-bonded.
  • the electret laminate obtained by this method is cut into a predetermined size, then polarized and charged by corona discharge or the like, and then subjected to an aging treatment, which is used for an earphone, a headphone, a microphone, or the like.
  • Another method for producing a heat-resistant electret of the present invention comprises coating a surface of a metal plate with a resin composition containing a fluororesin, and then foaming the resin composition, so that the surface of the metal plate has a fluorine content. It is characterized in that a porous resin layer containing a resin is formed.
  • a resin composition containing a fluororesin and a solvent is coated on a metal plate by using a spray or the like, and foamed when the resin composition is fired, so that the surface of the metal plate contains the fluororesin.
  • a porous resin layer can be formed.
  • a method of foaming a method using a foaming agent, a method of baking under reduced pressure, or the like can be used.
  • Still another method for producing a heat-resistant electret of the present invention comprises the steps of: coating a surface of a metal plate with a resin composition containing a fluororesin and an additive resin that decomposes at a lower temperature than the fluororesin; By baking, the additional resin is decomposed and removed, and a porous resin layer containing a fluorine resin is formed on the surface of the metal plate.
  • the shape of the porous resin layer can be arbitrarily controlled by changing the size and shape of the additional resin.
  • the above-mentioned additive resin polyethylene, silicone, or the like can be used.
  • the fluororesin is fired at a temperature close to 400, the above-mentioned added resin is decomposed and disappears during the firing to form voids.
  • the method comprises coating a resin composition containing a powdery fluororesin on a surface of a metal plate to form voids, and then firing the resin composition. Thereby, a porous resin layer containing a fluororesin is formed on the surface of the metal plate.
  • the form of the porous resin layer can be arbitrarily controlled by changing the size and shape of the powder and the thickness of the coating layer without using a foaming agent or an additional resin.
  • an electrostatic acoustic sensor includes the heat-resistant electret.
  • Examples of the electrostatic acoustic sensor include a microphone, an earphone, a headphone, a hearing aid, an ultrasonic sensor, and an acceleration sensor.
  • a PTFE nonwoven fabric with a basis weight of 50 gZm 2 manufactured by Daikin Industries, Ltd. was compacted with one roll of a calendar, and this PTFE nonwoven fabric was prepared as an electret material.
  • This PTFE nonwoven fabric and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into a size of 50 cm in length and 2 Ocm in width to obtain an electret of Example 1. Thermocompression bonding was performed at a temperature of 33 ° C. and a pressure of 3 kgf / cm 2 .
  • FIG. 1 is a cross-sectional view of the electret manufactured in this example.
  • the PTF E nonwoven fabric 2 and the stainless steel plate 3 are heated. It is formed by crimping.
  • a nonwoven fabric of PTF E having a basis weight of 150 gZm 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • This PTFE nonwoven fabric and a 0.2 mm thick stainless steel plate were thermocompression bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 2.
  • the thermocompression bonding was performed at a temperature of 36 o and a pressure of 6 kgf Zcm 2 .
  • a nonwoven fabric of PTF E having a basis weight of 150 g / m 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • This PTFE nonwoven fabric and a 0.2-mm-thick stainless steel sheet were thermocompression-bonded using a heating nozzle, and cut into the same size as in Example 1 to obtain an electret of Example 3.
  • the thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Z cm 2 .
  • PTFE nonwoven fabric with a basis weight of 250 g / m 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • This PTFE nonwoven fabric and a 0.2 mm thick stainless steel plate were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 4.
  • Thermocompression bonding temperature 360T, was performed at a pressure 3 kgf Bruno cm 2.
  • PTF E paper “PA-5L” manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • the PTFE paper and a stainless steel sheet having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 5.
  • Thermocompression bonding temperature 3 6 0 " was carried out at a pressure 6 kgf Zc m 2.
  • Example 6 PTFE paper "PA-5L” manufactured by Daikin Industries, Ltd. was prepared as an electret material. This PTFE paper and a 0.2 mm thick stainless steel plate were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 6. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Zcm 2 .
  • a sheet in which a nonwoven fabric and a 25 m thick PFA film “AF-0025” manufactured by Daikin Industries, Ltd. were laminated was prepared as an electret material.
  • the PTF E nonwoven fabric side of this sheet and a 0.2 mm thick stainless steel sheet were thermocompression bonded using a heating jar and cut into the same size as in Example 1 to obtain the electret of Example 7. Obtained.
  • the thermocompression bonding was performed at a temperature of 340 and a pressure of 3 kgf Zcm 2 .
  • Electret material is a sheet in which a PTF E nonwoven fabric with a basis weight of 250 gZm 2 manufactured by Daikin Industries and a PFA film “AF-0025” with a thickness of 25 ⁇ m manufactured by Daikin Industries, Ltd. are laminated.
  • Prepared as The PTF E nonwoven fabric side of this sheet and a 0.2 mm thick stainless steel plate were thermocompression bonded using a heating jar and cut into the same size as in Example 1 to obtain the electret of Example 8. Obtained. Thermocompression bonding was performed at a temperature of 340 and a pressure of 3 kgf Zcm 2 .
  • the thermocompression bonding was performed at a temperature of 360: and a pressure of 3 kg kgZcm 2 .
  • the thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kg fZcm 2 .
  • a film “920-UL” made by stacking six PTF E films each having a thickness of 25 zm manufactured by Nitto Denko Corporation was prepared as an electret material.
  • This film and a stainless steel plate having a thickness of 0.2 mm were heat-sealed using a heating roll and cut into the same size as in Example 1 to obtain an electret of Comparative Example 3.
  • the thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Zcm 2 .
  • a 25 m thick PFA film "AF-0025" manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • This film and a stainless steel sheet having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Comparative Example 4.
  • the thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf / cm 2 .
  • a 25 m thick FEP film "NF-0025" manufactured by Daikin Industries, Ltd. was prepared as an electret material.
  • This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Comparative Example 5.
  • the thermocompression bonding was performed at a temperature of 33 Ot: and a pressure of 3 kgf Zcm 2 .
  • Comparative Example 6 A 25 mm thick PTF E film "920-UL" manufactured by Nitto Denko Corporation was prepared as a material for electrets. This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll and cut into the same size as in Example 1 to obtain an electret of Comparative Example 6. Thermocompression bonding is performed at a temperature 340, was performed at a pressure 3 kg f Zc m 2.
  • the thickness, surface roughness, porosity, and residual potential of the electret surface of the thermocompression-bonded electret material were determined. It was measured.
  • the thickness of the electret material was determined by measuring the thickness of the electret layer other than the stainless steel plate using a micrometer.
  • the surface roughness of the material for electret was measured using a surface roughness meter "Sufet e-st -201" manufactured by Mityo Corporation.
  • the porosity of the electret material was measured from electron micrographs using an electron microscope "S-2380 NZEMAX-7000" manufactured by Hitachi.
  • the residual ratio of the surface potential of the electret was measured as follows. First, the sample was polarized with a negative corona discharge at a temperature of 25, and the surface potential immediately after that was measured with a surface electrometer "model344" manufactured by Trek. Subsequently, after holding at 270 or 300 for 10 minutes, the surface potential was measured in the same manner. Then, the surface potential immediately after the electret was subjected to the polarization treatment was determined as a reference (100%), and the surface potential after holding at 270: or 300 for 10 minutes was determined as its relative value (%).
  • Table 1 shows the results of the above measurements.
  • FIG. 2 shows the relationship between the surface potential remaining ratio and the temperature in Example 3 and Comparative Examples 4 to 6. (table 1 )
  • Example 16 As is clear from Table 1, the surface potential residual ratio of Example 16 is smaller than that of Comparative Example 1. It turns out that it is superior to all of 6. In addition, it can be seen that the residual ratio of surface potential at 300 ° C. in Examples 7 and 8 is superior to all Comparative Examples 16 and 17.
  • the porosity of the electret material the higher the residual ratio of the surface potential.
  • the porosity is preferably 50% or more.
  • the thickness of the electret material did not significantly affect the surface potential residual ratio.
  • the present invention provides a porous sheet containing fluorine resin on the surface of a metal plate, wherein the porous sheet has a porosity of 580%.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Laminated Bodies (AREA)

Abstract

A heat-resistant electret material which is a porous sheet (2) comprising a fluororesin and having a porosity of 15 to 80% is bonded to a surface of a metal sheet (3). A film comprising a fluororesin may be laminated to the porous sheet (2), whereby a smooth surface can be obtained. The metal sheet (3) is coated with a resin composition containing a fluororesin, and the resin composition applied is foamed to form a porous resin layer comprising a fluororesin on the surface of the metal sheet (3). Thus, an electret material having high heat resistance, a heat-resistant electret comprising the material, a process for producing the heat-resistant electret, and an electrostatic acoustic sensor can be provided.

Description

明 細 書  Specification
耐熱性エレクトレツ 卜材料の製法と、 該材料による静電型音饗センサ一 Method for producing heat-resistant electret material, and electrostatic sound sensor using the material
技術分野 Technical field
本発明は、 イヤホン、 ヘッドホンまたはマイクロホン等に使用される エレクトレツト用材料、 それを用いたエレクトレツトおよびその製造方 法、 並びに静電型音響センサ一に関する。 背景技術  The present invention relates to an electret material used for an earphone, a headphone, a microphone, or the like, an electret using the same, a method of manufacturing the same, and an electrostatic acoustic sensor. Background art
従来よりイヤホン、 へッドホンまたはマイクロホン等に使用されるェ レクトレツトとしては、 金属シートにエレクトレツ卜を構成しうる熱可 塑性樹脂フィルムをラミネートし、 この樹脂をエレクトレツト化する方 法が提案されている （特開昭 6 4 - 4 4 0 1 0号公報参照。 ） 。  Conventionally, as an electret used for an earphone, a headphone, a microphone, or the like, a method has been proposed in which a thermoplastic resin film capable of forming an electret is laminated on a metal sheet and the resin is electretized. (See JP-A-64-44010).
また、 テトラフルォロエチレン—へキサフルォロプロピレン共重合体 ( F E P ) の微粒子が分散された有機溶媒を金属板に塗布して薄膜を形 成し、 その薄膜をエレクトレツト化する方法 （特開平 1 1— 1 5 0 7 9 5号公報参照。 ） 、 また金属板に F E Pの微粒子が分散されたスプレー 液を噴霧した後、 焼成してエレクトレット化する方法 （特開 2 0 0 0— 1 1 5 8 9 5号公報参照。 ） 等も提案されている。  In addition, a method of forming a thin film by applying an organic solvent in which fine particles of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) are dispersed to a metal plate, and forming the thin film into an electret ( Also, a method of spraying a metal plate with a spray liquid in which fine particles of FEP are dispersed, followed by firing to form an electret (see Japanese Patent Application Laid-Open No. 2000-15095). See Japanese Patent Application Laid-Open No. 11-89595.
しかし、 従来のエレクトレットを用いてマイクロホン等を製造する際 にフロー装置ゃリフロー装置による半田付けを行うと、 半田付けの際の 高温によりエレクトレッ卜の機能が低下するという問題があった。 特に 最近では鉛フリー半田が多用されるにともない、 半田付け時の温度がさ らに高温の 2 6 0 程度となり、 エレクトレツ 卜の機能自体が喪失する という大きな問題が生じるおそれがある。 発明の開示 However, when a conventional electret is used to manufacture a microphone or the like and soldering is performed by a flow device / reflow device, there is a problem in that the function of the electret deteriorates due to a high temperature at the time of soldering. In particular, as lead-free solder has been used frequently recently, the temperature during soldering has increased. In addition, the high temperature of about 260 may cause a serious problem that the function of the electret is lost. Disclosure of the invention
本発明は、 フッ素樹脂を含む多孔性シートであって、 前記多孔性シー トの多孔度が 1 5〜 8 0 %であることを特徴とする耐熱性エレクトレッ ト用材料を提供する。  The present invention provides a heat-resistant electret material, which is a porous sheet containing a fluororesin, wherein the porous sheet has a porosity of 15 to 80%.
また、 本発明は、 金属板の表面に多孔性シートを配置した耐熱性エレ クトレッ トであって、 前記多孔性シートがフッ素樹脂を含み、 前記多孔 性シー卜の多孔度が 1 5〜8 0 %であることを特徴とする耐熱性エレク トレットを提供する。  The present invention also provides a heat-resistant electret comprising a metal sheet and a porous sheet disposed on a surface thereof, wherein the porous sheet contains a fluororesin, and the porosity of the porous sheet is 15 to 80. % Heat-resistant electret.
また、 本発明は、 金属板の表面に多孔性シートを貼り合わせる耐熱性 エレクトレットの製造方法であって、 前記多孔性シートがフッ素樹脂を 含み、 前記多孔性シートの多孔度が 1 5〜8 0 %であることを特徴とす る耐熱性エレクトレッ卜の製造方法を提供する。  Further, the present invention is a method for producing a heat-resistant electret in which a porous sheet is attached to a surface of a metal plate, wherein the porous sheet contains a fluororesin, and the porosity of the porous sheet is 15 to 80. %, And a method for producing a heat-resistant electret, characterized in that:
また、 本発明は、 フッ素樹脂を含む多孔性シートと、 フッ素樹脂を含 むフィルムとを貼り合わせた耐熱性エレクトレット用材料であって、 前 記多孔性シートの多孔度が 1 5〜8 0 %であることを特徴とする耐熱性 エレクトレツト用材料を提供する。  Further, the present invention is a heat-resistant electret material obtained by laminating a porous sheet containing a fluororesin and a film containing a fluororesin, wherein the porous sheet has a porosity of 15 to 80%. Disclosed is a heat-resistant material for electrets.
また、 本発明は、 金属板の表面に耐熱性エレクトレット用材料を配置 した耐熱性エレクトレットであって、 前記耐熱性エレクトレット用材料 が、 フッ素樹脂を含む多孔性シートと、 フッ素樹脂を含むフィルムとを 貼り合わせてなり、 前記多孔性シー卜の多孔度が 1 5〜 8 0 %であるこ とを特徴とする耐熱性エレクトレットを提供する。  Further, the present invention is a heat-resistant electret in which a heat-resistant electret material is disposed on a surface of a metal plate, wherein the heat-resistant electret material is a porous sheet containing a fluororesin, and a film containing a fluororesin. Provided is a heat-resistant electret, which is laminated and has a porosity of 15 to 80%.
また、 本発明は、 金属板の表面に耐熱性エレクトレット用材料を貼り 合わせる耐熱性エレクトレッ卜の製造方法であって、 前記耐熱性エレク トレット用材料が、 フッ素樹脂を含む多孔性シートと、 フッ素樹脂を含 むフィルムとを貼り合わせてなり、 前記多孔性シートの多孔度が 1 5〜 8 0 %であることを特徴とする耐熱性エレクトレツトの製造方法を提供 する。 The present invention also provides a method for producing a heat-resistant electret, which comprises bonding a heat-resistant electret material to a surface of a metal plate, A heat-resistant material comprising a porous sheet containing a fluororesin and a film containing a fluororesin, wherein the porosity of the porous sheet is 15 to 80%. Provide a manufacturing method of electret.
また、 本発明は、 金属板の表面にフッ素榭脂を含む樹脂組成物をコー ティングした後、 前記樹脂組成物を発泡させることにより、 前記金属板 の表面にフッ素樹脂を含む多孔性樹脂層を形成することを特徵とする耐 熱性エレクトレツトの製造方法を提供する。  Further, the present invention provides a method of coating a porous resin layer containing a fluorine resin on the surface of the metal plate by coating the surface of the metal plate with a resin composition containing the fluorine resin and then foaming the resin composition. Provided is a method for manufacturing a heat-resistant electret, which is characterized by being formed.
また、 本発明は、 金属板の表面にフッ素樹脂と、 フッ素樹脂より低い 温度で分解する添加樹脂とを含む樹脂組成物をコーティングした後、 前 記樹脂組成物を焼成することにより前記添加樹脂を分解 ·除去し、 前記 金属板の表面にフッ素樹脂を含む多孔性樹脂層を形成することを特徴と する耐熱性エレクトレツトの製造方法を提供する。  Further, the present invention provides a method for coating the surface of a metal plate with a resin composition containing a fluororesin and an additional resin that decomposes at a lower temperature than the fluororesin, and then firing the resin composition to form the additional resin. A method for producing a heat-resistant electret, which comprises decomposing and removing a porous resin layer containing a fluororesin on the surface of the metal plate.
また、 本発明は、 金属板の表面に粉体状のフッ素樹脂を含む樹脂組成 物をコーティングして空隙を形成した後、 前記樹脂組成物を焼成するこ とにより、 前記金属板の表面にフッ素樹脂を含む多孔性榭脂層を形成す ることを特徴とする耐熱性エレクトレットの製造方法を提供する。  In addition, the present invention provides a method for coating a surface of a metal plate with a fluorine-containing resin by coating the surface with a resin composition containing a powdery fluororesin to form voids, and then firing the resin composition. Provided is a method for manufacturing a heat-resistant electret, which comprises forming a porous resin layer containing a resin.
また、 本発明は、 上記耐熱性エレクトレットを備えたことを特徴とす る静電型音響センサ一を提供する。 図面の簡単な説明  The present invention also provides an electrostatic acoustic sensor including the heat-resistant electret described above. BRIEF DESCRIPTION OF THE FIGURES
図 1は、 実施例 1で作製したエレクトレットの断面図である。  FIG. 1 is a cross-sectional view of the electret manufactured in Example 1.
図 2は、 エレクトレツトの表面電位残存率と温度との関係を示す図で ある。 発明の実施の形態 本発明の耐熱性エレクトレツト用材料は、 フッ素樹脂を含む多孔性シFIG. 2 is a diagram showing the relationship between the residual ratio of the surface potential of the electret and the temperature. Embodiment of the Invention The heat-resistant electret material of the present invention is a porous sheet containing a fluororesin.
—トからなり、 その多孔性シートの多孔度が 1 5〜 8 0 %、 より好まし くは 50〜80 %であることを特徴とする。 The porous sheet is characterized in that the porosity of the porous sheet is 15 to 80%, more preferably 50 to 80%.
一般にフッ素樹脂は耐熱性が高い樹脂であり、 さらに多孔度が 1 5〜 8 0 %の多孔性フッ素樹脂シートをエレクトレツト用材料に用いること により、 高温時におけるエレクトレッ卜の表面電位の低下を抑制して、 エレクトレットの耐熱特性を向上できる。 ここで、 多孔度が 1 5 %を下 回ると高温でのエレクトレツ卜の表面電位の低下が大きくなるおそれが あり、 多孔度が 80 %を超えるとエレクトレット用材料としてのシート の作製が困難になる。 なお、 代表的なフッ素樹脂であるポリテトラフル ォロエチレン （PTF E) の融点は約 3 2 7でである。 これにより、 加 ェ温度が 300 程度になる ME MS (M i c r o E l e c t r o Me c h a n i c a l S y s t ems ) 技術を用いてマイクロホン等 を製造できる。  In general, fluororesin is a resin with high heat resistance, and by using a porous fluororesin sheet with a porosity of 15 to 80% as the material for electrets, the decrease in the surface potential of the electret at high temperatures is suppressed. Thus, the heat resistance of the electret can be improved. Here, if the porosity is less than 15%, the surface potential of the electret at a high temperature may decrease significantly, and if the porosity exceeds 80%, it becomes difficult to prepare a sheet as an electret material. . The melting point of polytetrafluoroethylene (PTFE), which is a typical fluororesin, is about 327. As a result, a microphone or the like can be manufactured by using the MEMS (Micro Electro t MeCh a n Si c Sy s tems) technology at which the heating temperature becomes about 300.
また、 本発明の耐熱性エレクトレット用材料は、 上記多孔性シートに 、 フッ素樹脂を含むフィルムをさらに貼り合わせることもできる。 これ により、 エレクトレットの表面を平滑にすることができ、 エレクトレツ トをマイクロホン等に使用した場合に振動板の動作を妨げない。  In the heat-resistant electret material of the present invention, a film containing a fluororesin may be further bonded to the porous sheet. This makes it possible to smooth the surface of the electret, and does not hinder the operation of the diaphragm when the electret is used for a microphone or the like.
また、 本発明の耐熱性エレクトレット用材料は、 上記フッ素樹脂が、 ポリテトラフルォロエチレン （PTF E) 、 テトラフルォロエチレン一 パ一フルォロアルキルビニルエーテル共重合体 （P FA) 、 テトラフル ォロエチレン—へキサフルォロプロピレン共重合体 （F EP) およびテ トラフルォロエチレン—パーフルォロメチルビ二ルエーテル （MF A) からなる群から選択された少なくとも 1つであることが好ましい。  Further, in the heat-resistant electret material of the present invention, the fluororesin is preferably polytetrafluoroethylene (PTF E), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene, It is preferably at least one selected from the group consisting of ethylene-hexafluoropropylene copolymer (F EP) and tetrafluoroethylene-perfluoromethylvinyl ether (MFA).
これらを用いることにより、 製品表面に防汚性、 耐薬品性、 撥水性、 耐候性等の優れた機能を付与できる。 また、 エレクトレットのフレキシ ピリティが損なわれない。 さらに、 エレクトレットのエンボス加工など も比較的容易に出来る。 By using these, excellent functions such as antifouling property, chemical resistance, water repellency, and weather resistance can be imparted to the product surface. Also, electret flexi Pity is not spoiled. Electret embossing is also relatively easy.
また、 上記多孔性シートの誘電率および体積抵抗率は、 それぞれ 2 . 1以下、 1 . 0 X 1 0 1 6 Q c m以上である。 なお、 誘電率の下限値は 、 空気の誘電率 = 1に近いほど好ましい。 また、 多孔性シートとするこ とにより、 フッ素榭脂そのものの誘電率より、 見かけ上の誘電率は低く なる。 The dielectric constant and volume resistivity of the porous sheet are 2.1 or less and 1.0 X 10 16 Qcm or more, respectively. The lower limit of the permittivity is preferably as close to the permittivity of air = 1 as possible. Further, by using a porous sheet, the apparent dielectric constant is lower than the dielectric constant of the fluororesin itself.
また、 本発明の耐熱性エレクトレツ卜は、 金属板の表面に、 上記耐熱 性エレクトレット用材料を配置したことを特徵とする。 これにより、 耐 熱性に優れたエレクトレツトを提供できる。  Further, the heat-resistant electret of the present invention is characterized in that the heat-resistant electret material is disposed on a surface of a metal plate. As a result, an electret having excellent heat resistance can be provided.
上記多孔性シートの厚さは特に限定されないが、 通常 5〜 4 0 0 m 、 好ましくは 1 0〜 5 0 mである。 この範囲内であれば、 エレクトレ ットの特性を維持しつつ、 エレクトレットの薄型化、 小型化が図れるか らである。 また、 上記多孔性シートの形態としては、 不織布、 織布、 ぺ 一パー、 延伸膜、 未焼成テープ等を使用できる。  The thickness of the porous sheet is not particularly limited, but is usually 5 to 400 m, preferably 10 to 50 m. Within this range, the electret can be made thinner and smaller while maintaining the characteristics of the electret. Further, as the form of the porous sheet, a nonwoven fabric, a woven fabric, a paper, a stretched film, an unsintered tape, or the like can be used.
また、 本発明の耐熱性エレクトレットは、 上記金属板が、 黄銅、 アル ミニゥム、 ステンレス鋼、 銅、 チタン、 洋白、 リン青銅、 それらの合金 、 それらがメツキされた金属およびそれらが蒸着された金属からなる群 から選択された少なくとも 1つから形成されていることが好ましい。 こ れらの金属は耐蝕性、 電気伝導性、 加工性の点で優れているからである なお、 上記金属板の使用にあたっては、 先ず油脂等の付着のないもの を用い、 さらには上記多孔性シートとの接着性を良くするために下地処 理を行うことが好ましい。 下地処理は、 例えば、 陽極酸化、 化成処理に よる皮膜の形成或いはカップリング剤の利用、 その他接着性を改善する 方法等が挙げられる。 また、 本発明の耐熱性エレクトレットの製造方法は、 金属板の表面に 、 上記耐熱性エレク卜レツト用材料を貼り合わせることを特徴とする。 即ち、 例えば、 多孔度が 1 5〜8 0 %のフッ素樹脂を含む多孔性シート を準備し、 加熱ロールおよび加熱源を有さないロールの一対からなる圧 着ロールのうち、 加熱ロール側に金属板を供給し、 加熱源を有さない口 —ル側に上記多孔性シートを供給しつつ、 上記圧着ロールの間に上記金 属板および上記多孔性シートを挿入し、 上記金属板と上記多孔性シート との接触時間を 1〜 3秒、 接触帯幅を 1〜2 0 mmに制御し、 上記金属 板と上記多孔性シー卜とを熱圧着することができる。 Further, in the heat-resistant electret of the present invention, the metal plate may be made of brass, aluminum, stainless steel, copper, titanium, nickel silver, phosphor bronze, an alloy thereof, a metal plated with the metal, and a metal on which the metal is deposited. It is preferably formed from at least one selected from the group consisting of This is because these metals are excellent in corrosion resistance, electrical conductivity, and workability. When using the above metal plate, first, use a metal plate free of oils and fats. It is preferable to perform a base treatment to improve the adhesiveness to the sheet. The underlayer treatment includes, for example, formation of a film by anodic oxidation or chemical conversion treatment, use of a coupling agent, and other methods for improving adhesion. Further, the method for producing a heat-resistant electret of the present invention is characterized in that the above-mentioned heat-resistant electret material is bonded to a surface of a metal plate. That is, for example, a porous sheet containing a fluororesin having a porosity of 15 to 80% is prepared, and a metal sheet is provided on the side of the heating roll in a pressing roll composed of a pair of a heating roll and a roll having no heating source. The metal plate and the porous sheet are inserted between the pressure rolls while supplying the plate and supplying the porous sheet to the nozzle side having no heating source. By controlling the contact time with the porous sheet to 1 to 3 seconds and the contact band width to 1 to 20 mm, the metal plate and the porous sheet can be thermocompression-bonded.
この方法により得られたエレクトレット用積層板は、 所定の大きさに 切断され、 次にコロナ放電等により分極帯電された後、 エージング処理 が行われ、 イヤホン、 ヘッドホンまたはマイクロホン等に利用される。 また、 本発明の耐熱性エレクトレットの他の製造方法は、 金属板の表 面にフッ素樹脂を含む樹脂組成物をコーティングした後、 この樹脂組成 物を発泡させることにより、 この金属板の表面にフッ素樹脂を含む多孔 性樹脂層を形成することを特徴とする。 即ち、 例えば、 フッ素樹脂と溶 剤とを含む樹脂組成物をスプレー等を用いて金属板にコーティングし、 その樹脂組成物を焼成する際に発泡させることにより、 金属板の表面に フッ素樹脂を含む多孔性樹脂層を形成することができる。 発泡させる手 段としては、 発泡剤を用いる方法、 または減圧下で焼成する方法などを 用いることができる。  The electret laminate obtained by this method is cut into a predetermined size, then polarized and charged by corona discharge or the like, and then subjected to an aging treatment, which is used for an earphone, a headphone, a microphone, or the like. Another method for producing a heat-resistant electret of the present invention comprises coating a surface of a metal plate with a resin composition containing a fluororesin, and then foaming the resin composition, so that the surface of the metal plate has a fluorine content. It is characterized in that a porous resin layer containing a resin is formed. That is, for example, a resin composition containing a fluororesin and a solvent is coated on a metal plate by using a spray or the like, and foamed when the resin composition is fired, so that the surface of the metal plate contains the fluororesin. A porous resin layer can be formed. As a method of foaming, a method using a foaming agent, a method of baking under reduced pressure, or the like can be used.
また、 本発明の耐熱性エレクトレットのさらに他の製造方法は、 金属 板の表面にフッ素樹脂と、 フッ素樹脂より低い温度で分解する添加樹脂 とを含む樹脂組成物をコーティングした後、 上記樹脂組成物を焼成する ことにより上記添加樹脂を分解 ·除去し、 上記金属板の表面にフッ素樹 脂を含む多孔性樹脂層を形成することを特徴とする。 上記添加樹脂の大きさ、 形を変えることにより、 多孔性樹脂層の形態 を任意に制御できる。 上記添加樹脂としては、 ポリエチレン、 シリコ一 ンなどを用いることができる。 通常、 フッ素樹脂は 40 0 近い温度で 焼成するため、 焼成時に上記添加樹脂が分解 ·消失して空隙が形成され る。 Further, still another method for producing a heat-resistant electret of the present invention comprises the steps of: coating a surface of a metal plate with a resin composition containing a fluororesin and an additive resin that decomposes at a lower temperature than the fluororesin; By baking, the additional resin is decomposed and removed, and a porous resin layer containing a fluorine resin is formed on the surface of the metal plate. The shape of the porous resin layer can be arbitrarily controlled by changing the size and shape of the additional resin. As the above-mentioned additive resin, polyethylene, silicone, or the like can be used. Usually, since the fluororesin is fired at a temperature close to 400, the above-mentioned added resin is decomposed and disappears during the firing to form voids.
また、 本発明の耐熱性エレクトレットのさらに他の製造方法は、 金属 板の表面に粉体状のフッ素樹脂を含む樹脂組成物をコーティングして空 隙を形成した後、 この樹脂組成物を焼成することにより、 この金属板の 表面にフッ素樹脂を含む多孔性樹脂層を形成することを特徴とする。 こ の方法では、 発泡剤や添加樹脂を用いなくても、 粉体の大きさ、 形、 コ 一ティング層の厚さなどを変えることにより、 多孔性樹脂層の形態を任 意に制御できる。  In still another method for producing a heat-resistant electret of the present invention, the method comprises coating a resin composition containing a powdery fluororesin on a surface of a metal plate to form voids, and then firing the resin composition. Thereby, a porous resin layer containing a fluororesin is formed on the surface of the metal plate. In this method, the form of the porous resin layer can be arbitrarily controlled by changing the size and shape of the powder and the thickness of the coating layer without using a foaming agent or an additional resin.
また、 本発明の静電型音響センサーは、 上記耐熱性エレク トレットを 備えたことを特徴とする。 静電型音響センサーとしては、 例えば、 マイ クロホン、 イヤホン、 ヘッドホン、 補聴器、 超音波センサー、 加速度セ ンサ一などが含まれる。  Further, an electrostatic acoustic sensor according to the present invention includes the heat-resistant electret. Examples of the electrostatic acoustic sensor include a microphone, an earphone, a headphone, a hearing aid, an ultrasonic sensor, and an acceleration sensor.
以下、 実施例と比較例を用いて本発明をさらに詳細に説明する。  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
(実施例 1)  (Example 1)
ダイキン工業社製の目付量 5 0 gZm2の P T F E不織布をカレンダ 一ロールで押し固め、 この P T F E不織布をエレクトレット用材料とし て準備した。 この PTFE不織布と、 厚さ 0. 2mmのステンレス鋼板 とを加熱ロールを用いて熱圧着し、 縦 5 0 cm、 横 2 O cmの大きさに 切断して実施例 1のエレクトレツトを得た。 熱圧着は、 温度 33 o , 圧力 3 k g f /cm2で行った。 A PTFE nonwoven fabric with a basis weight of 50 gZm 2 manufactured by Daikin Industries, Ltd. was compacted with one roll of a calendar, and this PTFE nonwoven fabric was prepared as an electret material. This PTFE nonwoven fabric and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into a size of 50 cm in length and 2 Ocm in width to obtain an electret of Example 1. Thermocompression bonding was performed at a temperature of 33 ° C. and a pressure of 3 kgf / cm 2 .
図 1は、 本実施例で作製したエレクトレットの断面図である。 本実施 例のエレクトレット 1は、 PTF E不織布 2とステンレス鋼板 3とが熱 圧着されて形成されている。 FIG. 1 is a cross-sectional view of the electret manufactured in this example. In the electret 1 of this embodiment, the PTF E nonwoven fabric 2 and the stainless steel plate 3 are heated. It is formed by crimping.
(実施例 2)  (Example 2)
ダイキン工業社製の目付量 1 50 gZm2の PTF E不織布をエレク トレット用材料として準備した。 この PTF E不織布と、 厚さ 0. 2m mのステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と同様 の大きさに切断して実施例 2のエレクトレットを得た。 熱圧着は、 温度 36 o , 圧力 6 k g f Zcm2で行った。 A nonwoven fabric of PTF E having a basis weight of 150 gZm 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material. This PTFE nonwoven fabric and a 0.2 mm thick stainless steel plate were thermocompression bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 2. The thermocompression bonding was performed at a temperature of 36 o and a pressure of 6 kgf Zcm 2 .
(実施例 3)  (Example 3)
ダイキン工業社製の目付量 1 5 0 g/m2の PTF E不織布をエレク トレット用材料として準備した。 この P TF E不織布と、 厚さ 0. 2m mのステンレス鋼板とを加熱口一ルを用いて熱圧着し、 実施例 1と同様 の大きさに切断して実施例 3のエレク卜レットを得た。 熱圧着は、 温度 360で、 圧力 3 k g f Z c m2で行った。 A nonwoven fabric of PTF E having a basis weight of 150 g / m 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material. This PTFE nonwoven fabric and a 0.2-mm-thick stainless steel sheet were thermocompression-bonded using a heating nozzle, and cut into the same size as in Example 1 to obtain an electret of Example 3. Was. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Z cm 2 .
(実施例 4)  (Example 4)
ダイキン工業社製の目付量 2 50 g/m2の PT F E不織布をエレク トレット用材料として準備した。 この PTF E不織布と、 厚さ 0. 2m mのステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と同様 の大きさに切断して実施例 4のエレクトレットを得た。 熱圧着は、 温度 360T、 圧力 3 k g f ノ cm2で行った。 PTFE nonwoven fabric with a basis weight of 250 g / m 2 manufactured by Daikin Industries, Ltd. was prepared as an electret material. This PTFE nonwoven fabric and a 0.2 mm thick stainless steel plate were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 4. Thermocompression bonding temperature 360T, was performed at a pressure 3 kgf Bruno cm 2.
(実施例 5)  (Example 5)
ダイキン工業社製の P TF Eペーパー "P A— 5 L" をエレクトレツ ト用材料として準備した。 この P T F Eペーパーと、 厚さ 0. 2mmの ステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と同様の大 きさに切断して実施例 5のエレクトレットを得た。 熱圧着は、 温度 3 6 0 " 、 圧力 6 k g f Zc m2で行った。 PTF E paper “PA-5L” manufactured by Daikin Industries, Ltd. was prepared as an electret material. The PTFE paper and a stainless steel sheet having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 5. Thermocompression bonding temperature 3 6 0 ", was carried out at a pressure 6 kgf Zc m 2.
(実施例 6) ダイキン工業社製の PT F Eペーパー "PA— 5 L" をエレクトレツ ト用材料として準備した。 この PTF Eペーパーと、 厚さ 0. 2mmの ステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と同様の大 きさに切断して実施例 6のエレクトレットを得た。 熱圧着は、 温度 3 6 0で、 圧力 3 k g f Zcm2で行った。 (Example 6) PTFE paper "PA-5L" manufactured by Daikin Industries, Ltd. was prepared as an electret material. This PTFE paper and a 0.2 mm thick stainless steel plate were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Example 6. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Zcm 2 .
(実施例 7)  (Example 7)
ダイキン工業社製の目付量 1 508 1112の？丁 £不織布と、 ダイ キン工業社製の厚さ 2 5 mの P FAフィルム "AF— 00 2 5 " とを 貼り合わせたシートをエレク卜レツト用材料として準備した。 このシー トの PTF E不織布側と、 厚さ 0. 2mmのステンレス鋼板とを加熱口 ールを用いて熱圧着し、 実施例 1と同様の大きさに切断して実施例 7の エレクトレツトを得た。 熱圧着は、 温度 340 、 圧力 3 k g f Zcm 2で行った。 Weight per unit manufactured by Daikin Industries 1 508 111 2 ? A sheet in which a nonwoven fabric and a 25 m thick PFA film “AF-0025” manufactured by Daikin Industries, Ltd. were laminated was prepared as an electret material. The PTF E nonwoven fabric side of this sheet and a 0.2 mm thick stainless steel sheet were thermocompression bonded using a heating jar and cut into the same size as in Example 1 to obtain the electret of Example 7. Obtained. The thermocompression bonding was performed at a temperature of 340 and a pressure of 3 kgf Zcm 2 .
(実施例 8)  (Example 8)
ダイキン工業社製の目付量 2 50 gZm2の PTF E不織布と、 ダイ キン工業社製の厚さ 2 5 ^mの P FAフィルム "AF— 00 2 5 " とを 貼り合わせたシートをエレクトレット用材料として準備した。 このシー 卜の PTF E不織布側と、 厚さ 0. 2mmのステンレス鋼板とを加熱口 ールを用いて熱圧着し、 実施例 1と同様の大きさに切断して実施例 8の エレクトレツトを得た。 熱圧着は、 温度 340 ：、 圧力 3 k g f Zcm 2で行った。 Electret material is a sheet in which a PTF E nonwoven fabric with a basis weight of 250 gZm 2 manufactured by Daikin Industries and a PFA film “AF-0025” with a thickness of 25 ^ m manufactured by Daikin Industries, Ltd. are laminated. Prepared as The PTF E nonwoven fabric side of this sheet and a 0.2 mm thick stainless steel plate were thermocompression bonded using a heating jar and cut into the same size as in Example 1 to obtain the electret of Example 8. Obtained. Thermocompression bonding was performed at a temperature of 340 and a pressure of 3 kgf Zcm 2 .
(比較例 1)  (Comparative Example 1)
ダイキン工業社製の厚さ 50 mの P F Aフィルムを 3枚重ねたフィ ルム "AF— 00 50 " をエレクトレツト用材料として準備した。 この フィルムと、 厚さ 0. 2 mmのステンレス鋼板とを加熱ロールを用いて 熱圧着し、 実施例 1と同様の大きさに切断して比較例 1のエレクトレツ トを得た。 熱圧着は、 温度 360 ：、 圧力 3 k g ί Zcm2で行った。 (比較例 2) A film “AF-0050” made by stacking three PFA films each having a thickness of 50 m, manufactured by Daikin Industries, Ltd., was prepared as an electret material. This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, cut into the same size as in Example 1, and electreted in Comparative Example 1. I got it. The thermocompression bonding was performed at a temperature of 360: and a pressure of 3 kg kgZcm 2 . (Comparative Example 2)
ダイキン工業社製の厚さ 50 mの FE Pフィルムを 3枚重ねたフィ ルム "N F— 00 50 " をエレクトレツト用材料として準備した。 この フィルムと、 厚さ 0. 2mmのステンレス鋼板とを加熱ロールを用いて 熱圧着し、 実施例 1と同様の大ぎさに切断して比較例 2のエレクトレッ トを得た。 熱圧着は、 温度 360で、 圧力 3 kg fZcm2で行った。 A film "NF-0050" made by stacking three 50 m thick FEP films manufactured by Daikin Industries, Ltd. was prepared as an electret material. This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same large pieces as in Example 1 to obtain an electret of Comparative Example 2. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kg fZcm 2 .
(比較例 3)  (Comparative Example 3)
日東電工社製の厚さ 2 5 zmの PTF Eフィルムを 6枚重ねたフィル ム " 9 20—UL" をエレクトレット用材料として準備した。 このフィ ルムと、 厚さ 0. 2 mmのステンレス鋼板とを加熱ロールを用いて熱圧 着し、 実施例 1と同様の大きさに切断して比較例 3のエレクトレットを 得た。 熱圧着は、 温度 360 、 圧力 3 k g f Zcm2で行った。 A film “920-UL” made by stacking six PTF E films each having a thickness of 25 zm manufactured by Nitto Denko Corporation was prepared as an electret material. This film and a stainless steel plate having a thickness of 0.2 mm were heat-sealed using a heating roll and cut into the same size as in Example 1 to obtain an electret of Comparative Example 3. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf Zcm 2 .
(比較例 4)  (Comparative Example 4)
ダイキン工業社製の厚さ 2 5 mの P FAフィルム "AF— 00 2 5 " をエレクトレット用材料として準備した。 このフィルムと、 厚さ 0. 2 mmのステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と 同様の大きさに切断して比較例 4のエレクトレットを得た。 熱圧着は、 温度 3 60で、 圧力 3 k g f /cm2で行った。 A 25 m thick PFA film "AF-0025" manufactured by Daikin Industries, Ltd. was prepared as an electret material. This film and a stainless steel sheet having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Comparative Example 4. The thermocompression bonding was performed at a temperature of 360 and a pressure of 3 kgf / cm 2 .
(比較例 5 )  (Comparative Example 5)
ダイキン工業社製の厚さ 2 5 mの FE Pフィルム "NF— 00 2 5 " をエレクトレット用材料として準備した。 このフィルムと、 厚さ 0. 2 mmのステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と 同様の大きさに切断して比較例 5のエレクトレツトを得た。 熱圧着は、 温度 3 3 Ot:、 圧力 3 k g f Zcm 2で行った。 A 25 m thick FEP film "NF-0025" manufactured by Daikin Industries, Ltd. was prepared as an electret material. This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll, and cut into the same size as in Example 1 to obtain an electret of Comparative Example 5. The thermocompression bonding was performed at a temperature of 33 Ot: and a pressure of 3 kgf Zcm 2 .
(比較例 6) 日東電工社製の厚さ 25 ΠΙの PTF Eフィルム " 920— UL" を エレクトレット用材料として準備した。 このフィルムと、 厚さ 0. 2m mのステンレス鋼板とを加熱ロールを用いて熱圧着し、 実施例 1と同様 の大きさに切断して比較例 6のエレクトレットを得た。 熱圧着は、 温度 340で、 圧力 3 kg f Zc m2で行った。 (Comparative Example 6) A 25 mm thick PTF E film "920-UL" manufactured by Nitto Denko Corporation was prepared as a material for electrets. This film and a stainless steel plate having a thickness of 0.2 mm were thermocompression-bonded using a heating roll and cut into the same size as in Example 1 to obtain an electret of Comparative Example 6. Thermocompression bonding is performed at a temperature 340, was performed at a pressure 3 kg f Zc m 2.
次に、 これらの実施例 1〜8、 比較例 1〜6のエレクトレットを用い て、 熱圧着したエレクトレツ卜用材料の厚さ、 その表面粗さ、 その多孔 度、 およびエレクトレットの表面電位残存率を測定した。  Next, using the electrets of Examples 1 to 8 and Comparative Examples 1 to 6, the thickness, surface roughness, porosity, and residual potential of the electret surface of the thermocompression-bonded electret material were determined. It was measured.
エレクトレット用材料の厚さは、 マイクロメータ一を用いてエレクト レツトのステンレス鋼板以外の層厚さを測定して求めた。 エレクトレツ ト用材料の表面粗さは、 ミットヨ社製の表面粗さ計 "S u f e t e s t — 20 1 " を用いて測定した。 エレクトレット用材料の多孔度は、 日立 製の電子顕微鏡 "S— 2380 NZEMAX— 7000 " を用いた電子 顕微鏡写真から測定した。  The thickness of the electret material was determined by measuring the thickness of the electret layer other than the stainless steel plate using a micrometer. The surface roughness of the material for electret was measured using a surface roughness meter "Sufet e-st -201" manufactured by Mityo Corporation. The porosity of the electret material was measured from electron micrographs using an electron microscope "S-2380 NZEMAX-7000" manufactured by Hitachi.
また、 エレクトレットの表面電位残存率は、 次のようにして測定した 。 まず、 マイナスのコロナ放電にて温度 25 で試料を分極処理し、 そ の直後の表面電位を T r e k社製の表面電位計 "mod e l 344" にて測定した。 続いて、 270 または 300 にて 10分間保持した 後、 その表面電位を同様にして測定した。 そして、 エレクトレットを分 極処理した直後の表面電位を基準 （ 100 %) として、 270 :または 300でで 10分間保持した後の表面電位をその相対値 （％) として求 めた。  Further, the residual ratio of the surface potential of the electret was measured as follows. First, the sample was polarized with a negative corona discharge at a temperature of 25, and the surface potential immediately after that was measured with a surface electrometer "model344" manufactured by Trek. Subsequently, after holding at 270 or 300 for 10 minutes, the surface potential was measured in the same manner. Then, the surface potential immediately after the electret was subjected to the polarization treatment was determined as a reference (100%), and the surface potential after holding at 270: or 300 for 10 minutes was determined as its relative value (%).
以上の測定の結果を表 1に示す。 また、 図 2には、 実施例 3および比 較例 4〜 6の表面電位残存率と温度との関係を示した。 (表 1 ) Table 1 shows the results of the above measurements. FIG. 2 shows the relationship between the surface potential remaining ratio and the temperature in Example 3 and Comparative Examples 4 to 6. (table 1 )
表 面 粗 さ 7 f η τ Π T 厚 さ 多孔度  Surface roughness 7 f η τ Π T Thickness Porosity
R a R a R a R a の残存率 u m )  R a R a R a Ra Remaining rate u m)
(横） (max) (縦） (max) 、  (Horizontal) (max) (vertical) (max),
V 1 . 6 7 1 5 . 8 1 . 1 7 7 . 4 リ ο 夫 E 'J 1 1 n 8 . 9 5 4 6 - 9 4 6 8 o 4 蓥旆例 3 1 3 0 7 . 0 1 4 9 . 6 4 . 6 6 2 7 4 5 4 9 o 8 1 実施例 4 1 7 0 5 . 6 1 2 9 . 9 6 . 8 2 4 4 6 5 3 8 7 7 3 実施例 5 3 7 0 2 . 2 1 1 7 . 2 2 . 3 8 1 7 9 3 2 8 7 5 4 実施例 6 4 0 0 7 . 0 7 4 0 . 6 8 . 3 9 4 0 5 0 9 0 7 5 実施例 7 1 4 0 0 . 5 9 2 . 7 0 . 6 6 6 - 1 5 4 5 0 4 7 実施例 8 2 2 0 0 . 6 7 3 . 5 1 . 1 4 6 . 7 5 3 6 1 5 5 比較例 1 1 3 0 0 . 1 9 0 . 9 0 - 1 0 . 5 0 0 0 比較例 2 1 3 0 0 . 1 0 - 6 0 . 1 0 . 5 0 0 0 比較例 3 1 3 0 0 - 8 6 . 3 0 . 8 5 . 3 0 3 0 比較例 4 2 3 0 . 5 5 3 . 4 0 . 5 6 3 . 4 0 0 0 比較例 5 2 3 0 . 5 1 4 . 1 0 . 4 5 4 . 9 0 1 0 比較例 6 2 3 0 . 2 6 1 . 8 0 . 3 1 2 0 5 4 2 2 表 1から明らかなように、 実施例 1 6の表面電位残存率は、 比較例 1 6の全てに比べて優れていることが分かる。 また、 実施例 7および 実施例 8の 3 0 0 °Cにおける表面電位残存率は、 比較例 1 6の全てに 比べて優れていることが分かる。  V 1 .6 7 1 5 .8 1 .1 77.4 4 ο Huo E 'J 1 1 n 8 .9 5 4 6-9 4 6 8 o 4 Example 3 1 3 0 7 .0 1 4 9.6 4 .6 6 2 7 4 5 4 9 o 8 1 Example 4 1 7 0 5 .6 1 2 9 .9 6 .8 2 4 4 6 5 3 8 7 7 3 Example 5 3 7 0 2 2 1 1 7 .2 2 .3 8 1 7 9 3 2 8 7 5 4 Example 6 4 0 0 7 .0 7 4 0 .6 8 .3 9 4 0 5 0 9 0 7 5 Example 7 1 4 0 .5 9 2 .7 0 .6 6 6-1 5 4 5 0 4 7 Example 8 2 2 0 .0 6 .7 3 .5 1 .1 4 6 .7 5 3 6 1 5 5 Comparative example 1 1 3 0 0 .1 9 0 .9 0-1 0 .5 0 0 0 Comparative example 2 1 3 0 0 .1 0-6 0 .1 0 .5 0 0 0 Comparative example 3 1 3 0 0-8 6.30.85.30.30 Comparative Example 42.30.55.3.4.05 63.400.000 Comparative Example 52.30.54.10.45 4.9 0 10 Comparative Example 6 2 3 0. 2 6 1 .8 0 .3 1 2 0 5 4 2 2 As is clear from Table 1, the surface potential residual ratio of Example 16 is smaller than that of Comparative Example 1. It turns out that it is superior to all of 6. In addition, it can be seen that the residual ratio of surface potential at 300 ° C. in Examples 7 and 8 is superior to all Comparative Examples 16 and 17.
また、 実施例 1 6からエレクトレツト用材料の多孔度が高くなるほ ど表面電位の残存率は向上することが分かる。 特に、 多孔度が 5 0 %以 上が好ましい。  In addition, it can be seen from Example 16 that the higher the porosity of the electret material, the higher the residual ratio of the surface potential. In particular, the porosity is preferably 50% or more.
10 また、 実施例 7および実施例 8は、 比較例 1 6と同程度の表面粗さ であるが、 その内部に多孔部を備えているので、 表面電位の低下が抑え られている。  10 Further, in Examples 7 and 8, the surface roughness is almost the same as that of Comparative Example 16, but since a porous portion is provided inside, the decrease in surface potential is suppressed.
また、 エレクトレット用材料の厚さは、 表面電位残存率にはあまり影 響しなかった。  Also, the thickness of the electret material did not significantly affect the surface potential residual ratio.
15  15
産業上の利用の可能性  Industrial potential
以上のように本発明は、 金属板の表面に、 フッ素榭脂を含む多孔性シ ートであって、 上記多孔性シートの多孔度が 1 5 8 0 %である耐熱性 エレクトレツト用材料を貼り合わせることにより、 耐熱性に優れたエレ クトレツトおよびそれを用いた各種の静電型音響センサーを提供でき、 その工業的価値は大である。 As described above, the present invention provides a porous sheet containing fluorine resin on the surface of a metal plate, wherein the porous sheet has a porosity of 580%. By bonding the material for electret, it is possible to provide an electret excellent in heat resistance and various electrostatic acoustic sensors using it, and its industrial value is great.

Claims

請 求 の 範 囲 The scope of the claims
1. フッ素樹脂を含む多孔性シートであって、 前記多孔性シートの多 孔度が 1 5〜8 0 %であることを特徴とする耐熱性エレクトレット用材 料。 1. A heat-resistant electret material, which is a porous sheet containing a fluororesin, wherein the porous sheet has a porosity of 15 to 80%.
2. 前記フッ素樹脂が、 ポリテトラフルォロエチレン （PTFE) 、 テトラフルォロエチレン一パーフルォロアルキルビニルエーテル共重合 体 （P FA) 、 テトラフルォロエチレン—へキサフルォロプロピレン共 重合体 （F E P) およびテトラフルォロエチレン一パーフルォロメチル ビニルエーテル （MFA) からなる群から選択された少なくとも 1つで ある請求項 1に記載の耐熱性エレク卜レツト用材料。  2. The fluororesin is made of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene. 2. The heat-resistant electret material according to claim 1, which is at least one selected from the group consisting of a polymer (FEP) and tetrafluoroethylene-perfluoromethyl vinyl ether (MFA).
3. 前記多孔性シートの誘電率および体積抵抗率が、 それぞれ 2. 1 以下、 1. 0 X 1 016Ω c m以上である請求項 1に記載の耐熱性エレ クトレツト用材料。 3. The heat-resistant electret material according to claim 1, wherein the dielectric constant and the volume resistivity of the porous sheet are 2.1 or less and 1.0 × 10 16 Ωcm or more, respectively.
4. 金属板の表面に多孔性シートを配置した耐熱性エレクトレッ卜で あって、 4. A heat-resistant electret in which a porous sheet is arranged on the surface of a metal plate,
前記多孔性シートがフッ素樹脂を含み、  The porous sheet contains a fluororesin,
前記多孔性シートの多孔度が 1 5〜80 %であることを特徴とする耐 熱性エレクトレット。  A heat-resistant electret, wherein the porosity of the porous sheet is 15 to 80%.
5. 前記金属板が、 黄銅、 アルミニウム、 ステンレス鋼、 銅、 チタン 、 洋白、 リン青銅、 それらの合金、 それらがメツキされた金属およびそ れらが蒸着された金属からなる群から選択された少なくとも 1つから形 成されている請求項 4に記載の耐熱性エレクトレツト。  5. The metal plate is selected from the group consisting of brass, aluminum, stainless steel, copper, titanium, nickel silver, phosphor bronze, alloys thereof, metal coated with them, and metal on which they are deposited. The heat-resistant electret according to claim 4, wherein the heat-resistant electret is formed from at least one.
6. 金属板の表面に多孔性シートを貼り合わせる耐熱性エレクトレツ 卜の製造方法であって、  6. A method for producing a heat-resistant electret in which a porous sheet is attached to a surface of a metal plate,
前記多孔性シートがフッ素樹脂を含み、 前記多孔性シートの多孔度が 1 5〜80 %であることを特徴とする耐 熱性エレクトレッ卜の製造方法。 The porous sheet contains a fluororesin, A method for producing a heat-resistant electret, wherein the porosity of the porous sheet is 15 to 80%.
7. フッ素樹脂を含む多孔性シートと、 フッ素樹脂を含むフィルムと を貼り合わせた耐熱性エレクトレット用材料であって、  7. A heat-resistant electret material obtained by laminating a porous sheet containing a fluororesin and a film containing a fluororesin,
前記多孔性シートの多孔度が 1 5〜 8 0 %であることを特徴とする耐 熱性エレクトレット用材料。  A heat-resistant electret material, wherein the porosity of the porous sheet is 15 to 80%.
8. 前記フッ素樹脂が、 ポリテトラフルォロエチレン （PTF E) 、 テトラフルォロエチレンーパ一フルォロアルキルビニルエーテル共重合 体 （P FA) 、 テトラフルォロエチレン—へキサフルォロプロピレン共 重合体 （F EP) およびテトラフルォロエチレン一パーフルォロメチル ビニルエーテル （MFA) からなる群から選択された少なくとも 1つで ある請求項 7に記載の耐熱性エレクトレツト用材料。  8. The fluororesin is polytetrafluoroethylene (PTF E), tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoro 8. The heat-resistant electret material according to claim 7, which is at least one selected from the group consisting of propylene copolymer (F EP) and tetrafluoroethylene-perfluoromethyl vinyl ether (MFA).
9. 前記多孔性シートの誘電率および体積抵抗率が、 それぞれ 2. 1 以下、 1. 0 X 1 016Ω c m以上である請求項 7に記載の耐熱性エレ クトレット用材料。 ， 9. The heat-resistant electret material according to claim 7, wherein the dielectric constant and the volume resistivity of the porous sheet are 2.1 or less and 1.0 × 10 16 Ωcm or more, respectively. ,
1 0. 金属板の表面に耐熱性エレクトレツト用材料を配置した耐熱性 エレク卜レットであって、  10. A heat-resistant electret having a heat-resistant electret material disposed on a surface of a metal plate,
前記耐熱性エレクトレット用材料が、 フッ素樹脂を含む多孔性シート と、 フッ素樹脂を含むフィルムとを貼り合わせてなり、  The heat-resistant electret material is obtained by laminating a porous sheet containing a fluororesin and a film containing a fluororesin,
前記多孔性シートの多孔度が 1 5〜 8 0 %であることを特徴とする耐 熱性エレクトレツト。  A heat-resistant electret, wherein the porosity of the porous sheet is 15 to 80%.
1 1. 前記金属板が、 黄銅、 アルミニウム、 ステンレス鋼、 銅、 チタ ン、 洋白、 リン青銅、 それらの合金、 それらがメツキされた金属および それらが蒸着された金属からなる群から選択された少なくとも 1つから 形成されている請求項 1 0に記載の耐熱性エレクトレット。  1 1. The metal plate is selected from the group consisting of brass, aluminum, stainless steel, copper, titanium, nickel silver, phosphor bronze, alloys thereof, metal coated with them, and metal on which they are deposited 10. The heat-resistant electret according to claim 10, formed from at least one.
1 2. 金属板の表面に耐熱性エレクトレツト用材料を貼り合わせる耐 熱性エレク卜レツ卜の製造方法であって、 1 2. A heat resistant electret material is stuck to the surface of a metal plate. A method for producing a thermoelectric electret, comprising:
前記耐熱性エレク トレツト用材料が、 フッ素樹脂を含む多孔性シート と、 フッ素樹脂を含むフィルムとを貼り合わせてなり、  The heat-resistant electret material is obtained by laminating a porous sheet containing a fluororesin and a film containing a fluororesin,
前記多孔性シートの多孔度が 1 5〜8 0 %であることを特徴とする耐 熱性エレクトレットの製造方法。  A method for producing a heat-resistant electret, wherein the porosity of the porous sheet is 15 to 80%.
1 3. 金属板の表面にフッ素樹脂を含む樹脂組成物をコーティングし た後、 前記樹脂組成物を発泡させることにより、 前記金属板の表面にフ ッ素樹脂を含む多孔性樹脂層を形成することを特徴とする耐熱性エレク トレツ卜の製造方法。  1 3. After coating the surface of a metal plate with a resin composition containing a fluororesin, the resin composition is foamed to form a porous resin layer containing a fluororesin on the surface of the metal plate. A method for producing a heat-resistant electret, comprising:
14. 前記多孔性樹脂層の多孔度が、 1 5〜8 0 %である請求項 1 3 に記載の耐熱性エレクトレツ卜の製造方法。  14. The method for producing a heat-resistant electret according to claim 13, wherein the porosity of the porous resin layer is 15 to 80%.
1 5. 金属板の表面にフッ素樹脂と、 フッ素樹脂より低い温度で分解 する添加樹脂とを含む樹脂組成物をコーティングした後、 前記樹脂組成 物を焼成することにより前記添加樹脂を分解 ·除去し、 前記金属板の表 面にフッ素樹脂を含む多孔性樹脂層を形成することを特徴とする耐熱性 エレクトレツ卜の製造方法。  1 5. After coating the surface of the metal plate with a resin composition containing a fluororesin and an additional resin that decomposes at a lower temperature than the fluororesin, the resin composition is fired to decompose and remove the additional resin. A method for producing a heat-resistant electret, comprising forming a porous resin layer containing a fluororesin on a surface of the metal plate.
1 6. 前記多孔性樹脂層の多孔度が、 1 5〜80 %である請求項 1 5 に記載の耐熱性エレクトレツ卜の製造方法。  16. The method for producing a heat-resistant electret according to claim 15, wherein the porosity of the porous resin layer is 15 to 80%.
1 7. 金属板の表面に粉体状のフッ素樹脂を含む樹脂組成物をコーテ イングして空隙を形成した後、 前記樹脂組成物を焼成することにより、 前記金属板の表面にフッ素樹脂を含む多孔性樹脂層を形成することを特 徵とする耐熱性エレクトレツトの製造方法。  1 7. After coating a resin composition containing a powdery fluororesin on the surface of the metal plate to form voids, baking the resin composition to include the fluororesin on the surface of the metal plate A method for producing a heat-resistant electret, comprising forming a porous resin layer.
1 8. 前記多孔性樹脂層の多孔度が、 1 5〜8 0 %である請求項 1 7 に記載の耐熱性エレクトレツ卜の製造方法。  18. The method for producing a heat-resistant electret according to claim 17, wherein the porosity of the porous resin layer is 15 to 80%.
1 9. 請求項 4、 5、 1 0、 または 1 1のいずれかに記載の耐熱性ェ レク卜レツトを備えたことを特徴とする静電型音響センサー。  1 9. An electrostatic acoustic sensor comprising the heat-resistant electret according to any one of claims 4, 5, 10, and 11.
PCT/JP2003/008396 2002-07-04 2003-07-02 Process for producing heat-resistant electret material and electrostatic acoustic sensor comprising the material WO2004006622A1 (en)

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JP2002-196397 2002-07-04
JP2002196397 2002-07-04

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06332305A (en) * 1993-05-19 1994-12-02 Mita Ind Co Ltd Polymer electret and sleeve for transporting developer by using the same
JPH1147521A (en) * 1997-08-04 1999-02-23 Toyobo Co Ltd Filter medium for air cleaning
JP2000032596A (en) * 1998-07-09 2000-01-28 Matsushita Electric Ind Co Ltd Manufacture of heat resistance electret condenser microphone
GB2352658A (en) * 1999-04-12 2001-02-07 Darwin Technology Ltd Electrostatic particle separation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06332305A (en) * 1993-05-19 1994-12-02 Mita Ind Co Ltd Polymer electret and sleeve for transporting developer by using the same
JPH1147521A (en) * 1997-08-04 1999-02-23 Toyobo Co Ltd Filter medium for air cleaning
JP2000032596A (en) * 1998-07-09 2000-01-28 Matsushita Electric Ind Co Ltd Manufacture of heat resistance electret condenser microphone
GB2352658A (en) * 1999-04-12 2001-02-07 Darwin Technology Ltd Electrostatic particle separation

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