JP2020116551A - Laminated polytetrafluoroethylene porous membrane and method for manufacture thereof - Google Patents
Laminated polytetrafluoroethylene porous membrane and method for manufacture thereof Download PDFInfo
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- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 195
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 195
- 239000012528 membrane Substances 0.000 title claims abstract description 129
- -1 polytetrafluoroethylene Polymers 0.000 title claims description 38
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- 238000000034 method Methods 0.000 title description 10
- 239000002245 particle Substances 0.000 claims abstract description 50
- 239000011148 porous material Substances 0.000 claims abstract description 17
- 239000003607 modifier Substances 0.000 claims abstract description 8
- 238000001125 extrusion Methods 0.000 claims description 52
- 238000000465 moulding Methods 0.000 claims description 38
- 238000002844 melting Methods 0.000 claims description 13
- 230000008018 melting Effects 0.000 claims description 13
- 238000010304 firing Methods 0.000 claims description 5
- 125000004432 carbon atom Chemical group C* 0.000 claims description 3
- UUAGAQFQZIEFAH-UHFFFAOYSA-N chlorotrifluoroethylene Chemical group FC(F)=C(F)Cl UUAGAQFQZIEFAH-UHFFFAOYSA-N 0.000 claims description 3
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical compound FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 235000012438 extruded product Nutrition 0.000 claims description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims 1
- 239000005977 Ethylene Substances 0.000 claims 1
- 230000035699 permeability Effects 0.000 abstract description 6
- 238000007720 emulsion polymerization reaction Methods 0.000 abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 28
- 239000000843 powder Substances 0.000 description 14
- 239000003921 oil Substances 0.000 description 13
- 235000019198 oils Nutrition 0.000 description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 10
- 238000005259 measurement Methods 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000004006 olive oil Substances 0.000 description 6
- 235000008390 olive oil Nutrition 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 239000004744 fabric Substances 0.000 description 4
- 239000010419 fine particle Substances 0.000 description 4
- 238000010030 laminating Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- CNPVJWYWYZMPDS-UHFFFAOYSA-N 2-methyldecane Chemical compound CCCCCCCCC(C)C CNPVJWYWYZMPDS-UHFFFAOYSA-N 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- 239000012752 auxiliary agent Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 210000002374 sebum Anatomy 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- BSYNRYMUTXBXSQ-UHFFFAOYSA-N Aspirin Chemical compound CC(=O)OC1=CC=CC=C1C(O)=O BSYNRYMUTXBXSQ-UHFFFAOYSA-N 0.000 description 1
- 239000004908 Emulsion polymer Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 239000000443 aerosol Substances 0.000 description 1
- LXQXZNRPTYVCNG-YPZZEJLDSA-N americium-241 Chemical compound [241Am] LXQXZNRPTYVCNG-YPZZEJLDSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000007600 charging Methods 0.000 description 1
- 230000009194 climbing Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000007786 electrostatic charging Methods 0.000 description 1
- 239000010462 extra virgin olive oil Substances 0.000 description 1
- 235000021010 extra-virgin olive oil Nutrition 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009998 heat setting Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/1213—Laminated layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/1216—Three or more layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/36—Polytetrafluoroethene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
- B29C67/20—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 for porous or cellular articles, e.g. of foam plastics, coarse-pored
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
- B32B5/32—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed at least two layers being foamed and next to each other
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/24—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by surface fusion and bonding of particles to form voids, e.g. sintering
Abstract
Description
本発明は、積層されたポリテトラフルオロエチレン（以下、「ポリテトラフルオロエチレン」を単に「ＰＴＦＥ」という。）の多孔膜及びその製法に関する。 The present invention relates to a laminated porous membrane of polytetrafluoroethylene (hereinafter, “polytetrafluoroethylene” is simply referred to as “PTFE”) and a method for producing the same.
なお、本明細書において、３４０℃以上に加熱する工程を経ていないＰＴＦＥを未焼成ＰＴＦＥという。ちなみにＰＴＦＥの融点といえば３４０℃であり、焼成されたＰＴＦＥの融点は３２７℃である。 In this specification, PTFE that has not undergone the step of heating to 340° C. or higher is referred to as unsintered PTFE. Incidentally, the melting point of PTFE is 340° C., and the melting point of fired PTFE is 327° C.
最近の半導体工業、精密工業、バイオテクノロジーなどにおける製造工程においては、高度に清浄化された空間や高度に清浄化された薬液が要求される。特に半導体工業において近来の高集積化に伴い微細な粒子の除去等、装置内部の雰囲気を高度に清浄化することが要請される。これらの課題を解決するために装備される高性能エアフィルタや薬液中の微細粒子除去フィルタにＰＴＦＥの多孔膜が濾材として使用されている。乳化重合によって得られた結晶化度９８％以上のＰＴＦＥファインパウダーにより、高倍率の延伸多孔膜を作成することが重要である。そして押出方向に沿った長手方向（以下、「ＭＤ方向」と称す。）と押出方向に直交する幅方向（以下、「ＴＤ方向」と称す）の延伸倍率を大きくしていけば、フィブリルが増大し、ノードが減少して厚みが薄くなり、孔径を小さくすることができる。この現象は、濾材にあっては、微細粒子の除去、透過流量の増大という好ましい結果をもたらす。 In the recent manufacturing processes in the semiconductor industry, precision industry, biotechnology, etc., a highly cleaned space and a highly cleaned chemical solution are required. Particularly in the semiconductor industry, with recent high integration, it is required to highly clean the atmosphere inside the device such as removal of fine particles. A porous membrane of PTFE is used as a filter medium in a high-performance air filter and a filter for removing fine particles in a chemical solution, which are equipped to solve these problems. It is important to prepare a stretched porous membrane of high magnification by using PTFE fine powder having a crystallinity of 98% or more obtained by emulsion polymerization. Then, if the stretching ratio in the longitudinal direction along the extrusion direction (hereinafter referred to as "MD direction") and the width direction orthogonal to the extrusion direction (hereinafter referred to as "TD direction") is increased, fibrils increase. However, the number of nodes is reduced, the thickness is reduced, and the hole diameter can be reduced. In the case of the filter medium, this phenomenon brings about favorable results such as removal of fine particles and increase in permeation flow rate.
ＰＴＦＥ多孔膜は、一般的に次のように製造される。すなわち、ＰＴＦＥを乳化重合することによって得られるＰＴＦＥファインパウダーに、成形助剤として石油溶剤等の溶剤を添加したペースト状の予備成形体を作製し、この予備成形体を押出成形金型となるシリンダーに装填する。そして、押出成形金型の先端に設置されたノズル部分から、前記ペースト状の予備成形体をロッド状又はシート状に押し出すとペースト状の押出成形体が作製される。ここまでの工程を本明細書においては「ペースト押出成形」または単に「ペースト押出」という。 The PTFE porous membrane is generally manufactured as follows. That is, a paste-like preform prepared by adding a solvent such as a petroleum solvent as a molding aid to a PTFE fine powder obtained by emulsion-polymerizing PTFE is prepared, and this preform is used as an extrusion molding cylinder. To load. Then, when the paste-like preform is extruded into a rod-like or sheet-like form from a nozzle portion provided at the tip of the extrusion-molding die, a paste-like extrusion-forming product is produced. In the present specification, the steps up to this point are referred to as “paste extrusion molding” or simply “paste extrusion”.
次に、前記押出成形体は、一対の金属ロールからなる圧延ロールによって、厚み５０〜１０００μｍの未焼成ＰＴＦＥフィルムに加工される。この段階における未焼成ＰＴＦＥフィルムには成形助剤が混入している。本明細書においては、この成形助剤が混入している未焼成ＰＴＦＥフィルムを「成形助剤混入フィルム」という。 Next, the extrusion-molded body is processed into an unsintered PTFE film having a thickness of 50 to 1000 μm by a rolling roll composed of a pair of metal rolls. A molding aid is mixed in the unsintered PTFE film at this stage. In the present specification, the unsintered PTFE film containing the molding aid is referred to as "molding aid-containing film".
このフィルムを揮発乾燥することにより前記の成形助剤を除去すると、成形助剤が除去された未焼成ＰＴＦＥフィルムが製造される。本明細書においては、成形助剤を除去した未焼成ＰＴＦＥフィルムを「成形助剤除去フィルム」という。 By removing the forming aid by volatilizing and drying this film, an unsintered PTFE film from which the forming aid is removed is produced. In the present specification, the unsintered PTFE film from which the molding aid has been removed is referred to as a "molding aid-removed film".
前記成形助剤除去フィルムは、ガス管等の管類が連結される接合ネジ部分のシールテープ、電気を絶縁するための電線被覆材、フラットケーブルの形成材料などの用途に使われる。 The forming aid removing film is used for applications such as a sealing tape for a joint screw portion to which pipes such as a gas pipe are connected, a wire covering material for insulating electricity, a flat cable forming material, and the like.
上記の成形助剤除去フィルムをＰＴＦＥの融点、すなわち３４０℃未満の温度に加熱して、当該フィルムをＭＤ方向に延伸し、さらにＴＤ方向に延伸し、延伸したのちにＰＴＦＥの融点以上の温度に加熱処理するとＰＴＦＥ多孔膜が製造される。 The above-mentioned molding aid removing film is heated to the melting point of PTFE, that is, a temperature of less than 340° C., the film is stretched in the MD direction, further stretched in the TD direction, and then stretched to a temperature equal to or higher than the melting point of PTFE. The heat treatment produces a porous PTFE membrane.
このＰＴＦＥ多孔膜は、スキーウエアや登山服、キャンプ用テント、自動車のランプ、ハードディスクなどのエアベンド、薬液フィルターやエアフィルターなどに使用される。 This PTFE porous membrane is used for ski wear, mountain climbing clothes, camping tents, automobile lamps, air bends for hard disks, chemical liquid filters, air filters and the like.
ところで、ＰＴＦＥ多孔膜は、その厚みが薄くなると、機械的強度が弱くなるため加工時点での帯電による放電破損が生じ、オイルミストなどが付着することにより通気性と粒子の捕集性能が低下し、液圧などの作用によってＰＴＦＥ多孔膜が厚み方向に圧縮されると隙間が減少するために流量低下が発生し、プリーツ加工時の曲げ加工で破損が生ずるなどの問題点がある。アパレル分野では通気性衣料品について、生地に界面活性剤が接触すると耐水性が低下し、皮脂などの油分が接触すると通気性が低下する問題点がある。 By the way, when the thickness of the PTFE porous membrane is reduced, the mechanical strength is weakened, and therefore discharge damage due to charging occurs at the time of processing, and oil mist or the like adheres to deteriorate the air permeability and the performance of collecting particles. When the PTFE porous film is compressed in the thickness direction by the action of hydraulic pressure, the gap decreases, resulting in a decrease in the flow rate, which causes a problem such as breakage during bending during pleating. In the field of apparel, regarding breathable clothing, there is a problem that when a fabric comes into contact with a surfactant, water resistance is reduced, and when oil such as sebum comes into contact with the fabric, breathability is reduced.
上記のような問題点に対して下記特許文献１に記載の発明が提案されている。すなわち、特許文献１による多孔質ＰＴＦＥ物品は、高強度、低い流れ抵抗、小孔径の組み合わせを提供するものである。 With respect to the above problems, the invention described in Patent Document 1 below has been proposed. That is, the porous PTFE article according to Patent Document 1 provides a combination of high strength, low flow resistance and small pore size.
しかし、上記特許文献１の方法では、まず助剤を除去していない圧延フィルムをＴＤ方向に延伸し、その後フィルムを積層して再度圧延を行い一体化する工程を経た上で、助剤を乾燥除去し、フィルムをＭＤ方向に延伸し、続いてＴＤ方向に延伸した後、焼結して作製する方法であり、前半の一体化工程が簡潔でない。 However, in the method of the above-mentioned Patent Document 1, first, a rolled film in which the auxiliary agent is not removed is stretched in the TD direction, and then the film is laminated, rolled again and integrated, and then the auxiliary agent is dried. This is a method in which the film is removed, the film is stretched in the MD direction, then stretched in the TD direction, and then sintered, and the integration process in the first half is not simple.
下記特許文献２においては、粒子の捕集効率を高めるために、微細孔を有するＰＴＦＥ多孔膜とその孔径より少し大きい５μｍ以下のＰＴＦＥ多孔膜を交互に積み重ねるという提案がなされている。 In Patent Document 2 below, in order to enhance the efficiency of collecting particles, it is proposed to alternately stack a PTFE porous membrane having fine pores and a PTFE porous membrane of 5 μm or less, which is slightly larger than the pore diameter thereof.
しかし、上記特許文献２の方法は、薄くて腰のない複数のＰＴＦＥ多孔膜を交互に積み重ねる作業上の困難性があり、また、容易に多孔膜が剥離する問題がある。 However, the method of Patent Document 2 has a difficulty in alternately stacking a plurality of thin and rigid PTFE porous membranes, and also has a problem that the porous membranes are easily peeled off.
上記のＰＴＦＥ多孔膜の積層方法については、下記特許文献３及び４に示される本願の発明者が提案した多層押出の方法により解決される。 The above-mentioned method for laminating the PTFE porous membrane can be solved by the multilayer extrusion method proposed by the inventor of the present application as shown in Patent Documents 3 and 4 below.
すなわち、下記特許文献３には、ＰＴＦＥ多孔膜の積層体の作製方法について、箱状の金型内に、第１層を得るためのＰＴＦＥペーストを層状に下金型上に乗せ、上金型で押圧する。こうして圧縮された第１層が形成される。次に上金型を取り外して、第２層を形成するためにＰＴＦＥペーストを入れ、上金型を用いて圧縮し、第１層の上に第２層を形成する。その後、さらに第３層のためのＰＴＦＥペーストを入れて上金型によって押圧する。こうして第１層、第２層及び第３層を有し、ペースト押出金型のシリンダーに収納される寸法に成形された複層予備成形体が得られる。この複層予備成形体を使用して、上記したＰＴＦＥ多孔膜の製造手順によりＰＴＦＥ多孔膜複層体が作製される。 That is, in Patent Document 3 below, regarding a method for producing a laminate of a PTFE porous membrane, a PTFE paste for obtaining a first layer is layered on a lower mold in a box-shaped mold, and an upper mold is prepared. Press with. A first layer thus compressed is formed. Next, the upper mold is removed, the PTFE paste is put in to form the second layer, and the upper mold is used for compression to form the second layer on the first layer. Then, the PTFE paste for the third layer is further added and pressed by the upper mold. Thus, a multi-layer preform having the first layer, the second layer and the third layer and having a size to be housed in the cylinder of the paste extrusion die is obtained. Using this multilayer preform, a PTFE porous membrane multilayer is produced by the above-described PTFE porous membrane manufacturing procedure.
なお、当該特許文献４には、ＰＴＦＥ多孔膜複層体を形成する層の組合せとして、平均分子量が相違するＰＴＦＥファインパウダー同士の組み合わせや低分子量重合体等の非繊維化物を含有しているＰＴＦＥファインパウダーの組み合わせが示されている。 In addition, in the said patent document 4, as a combination of layers which form a PTFE porous membrane multilayer, a combination of PTFE fine powders having different average molecular weights, or a PTFE containing a non-fibrous substance such as a low molecular weight polymer. A combination of fine powders is shown.
しかしながら、上記特許文献４においては、平均分子量が相違するＰＴＦＥファインパウダー同士を組み合わせた層や低分子量重合体等の非繊維化物を含有しているＰＴＦＥファインパウダーの層を中間層として介在させているが、未だ、上記の問題点を解決するに至っていない。 However, in the above Patent Document 4, a layer in which PTFE fine powders having different average molecular weights are combined with each other and a layer of PTFE fine powders containing a non-fibrous substance such as a low molecular weight polymer are interposed as an intermediate layer. However, the above problems have not been solved yet.
そこで、本発明者は、少なくとも三層のうちの中間層に、フィブリルの発現が少なく、多角形的に広がったノード層を構成する膜材料を、ペースト押出前の予備成形体の段階から作製し、通常の工程、すなわちペースト押出によるシートの作製、シートの圧延、助剤の乾燥除去、縦延伸、横延伸は従来の方法で行うことで、容易に上記の問題点が解決することを見出した。 Therefore, the present inventor produced, in at least the intermediate layer of the three layers, a film material forming a polygonally expanded node layer with less fibril expression from the stage of the preform before paste extrusion. It has been found that the above-mentioned problems can be easily solved by performing the ordinary steps, ie, the production of a sheet by paste extrusion, the rolling of the sheet, the drying and removal of the auxiliary agent, the longitudinal stretching and the transverse stretching, by a conventional method. ..
該発明の最大の特徴は、多層、すなわち少なくとも三層以上からなる積層構造において、中間層に０．５％以下のコモノマーが含まれた変性ＰＴＦＥファインパウダーの層を配置すること、三層構造の上下層は結晶化度９８％以上のＰＴＦＥファインパウダーであること、さらに圧延及び助剤除去されたフィルムをＭＤ方向に５倍以上、ＴＤ方向に２０倍以上延伸し、その後、焼結したＰＴＦＥ多孔膜の構造にしたこと、にある。 The greatest feature of the invention is that in a multilayer structure, that is, in a laminated structure composed of at least three layers or more, arranging a layer of modified PTFE fine powder containing 0.5% or less of a comonomer in an intermediate layer. The upper and lower layers are made of PTFE fine powder having a crystallinity of 98% or more, and the rolled and auxiliary-removed film is stretched 5 times or more in the MD direction and 20 times or more in the TD direction, and then sintered PTFE porous. It is because of the structure of the membrane.
このように構成したことによって得られる積層ＰＴＦＥ多孔膜は、中間層の変性ＰＴＦＥポリマーがほとんどフィブリルを形成せず、ノードのみとなり、大きな孔径を形成した膜となる。さらに厚みの減少率も上下面に比べはるかに小さいことにより全体の厚みを嵩上げする。 The laminated PTFE porous membrane obtained by having such a constitution is a membrane in which the modified PTFE polymer of the intermediate layer hardly forms fibrils, only the nodes are formed, and the large pore diameter is formed. Furthermore, the reduction rate of the thickness is much smaller than that of the upper and lower surfaces, thereby increasing the overall thickness.
本発明に係る第１の積層ＰＴＦＥ多孔膜は、第１層〜第３層の３つの層を含む３層以上の積層体から構成され、第１層及び第３層は、平均分子量が３００万以上のＰＴＦＥ乳化重合粒子により作製され、フィブリルとノードとにより形成された微細孔を有するＰＴＦＥ多孔膜層であり、第２層は、第１層と第３層との間に位置し、共重合性変性剤を含んだＰＴＦＥ乳化重合粒子により作製された難フィブリル化の変性ＰＴＦＥ多孔膜層であることを特徴とする。 The first laminated PTFE porous membrane according to the present invention is composed of a laminated body of three or more layers including three layers of a first layer to a third layer, and the first layer and the third layer have an average molecular weight of 3,000,000. A PTFE porous membrane layer made of the above PTFE emulsion-polymerized particles and having micropores formed by fibrils and nodes, wherein the second layer is located between the first layer and the third layer and is a copolymer. It is characterized in that it is a modified fibrillated modified PTFE porous membrane layer made of PTFE emulsion-polymerized particles containing a property-modifying agent.
本発明に係る第２の積層ＰＴＦＥ多孔膜は、前記第１の積層ＰＴＦＥ多孔膜の構成に加えて、前記共重合性変性剤は、ヘキサフルオロプロペン、ω−ヒドロパーフルオロオレフィン、トリフルオロクロロエチレン、炭素数３〜１０のパーフルオロアルキルトリフルオロエチレンのうちの少なくとも１種を使用してなることを特徴とする。 In the second laminated PTFE porous membrane according to the present invention, in addition to the constitution of the first laminated PTFE porous membrane, the copolymerizable modifier is hexafluoropropene, ω-hydroperfluoroolefin, trifluorochloroethylene. And at least one kind of perfluoroalkyl trifluoroethylene having 3 to 10 carbon atoms is used.
本発明に係る積層ＰＴＦＥ多孔膜の第１の製法は、前記第１の積層ＰＴＦＥ多孔膜における第１層を形成するための成形助剤添混入ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第２層を形成するための成形助剤混入変性ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第３層を形成するための成形助剤混入ＰＴＦＥ乳化重合粒子とを、第１層、第２層、第３層の順序に積層して予備成形体を作製し、当該予備成形体を押出成形金型に装填し、装填した前記予備成形体を当該押出成形金型から押し出して押出成形体を作製し、前記押出成形体から前記第１の積層ＰＴＦＥ多孔膜を製造することを特徴とする。 A first method for producing a laminated PTFE porous membrane according to the present invention is a step of forming a first layer in the first laminated PTFE porous membrane, wherein the PTFE emulsion-polymerized particles mixed with a molding aid are mixed with the first laminated PTFE porous membrane. Modified PTFE emulsion-polymerized particles mixed with a molding aid for forming the second layer in the membrane, and PTFE emulsion-polymerized particles mixed with a molding aid for forming the third layer in the first laminated PTFE porous membrane, A preform is prepared by laminating the first layer, the second layer, and the third layer in this order, the preform is loaded into an extrusion mold, and the loaded preform is extruded from the extrusion mold. An extrusion molded article is produced by manufacturing the extruded molded article, and the first laminated PTFE porous membrane is manufactured from the extrusion molded article.
本発明に係る積層ＰＴＦＥ多孔膜の第２の製法は、前記積層ＰＴＦＥ多孔膜の第１の製法における押出成形体を圧延及び乾燥して成形助剤除去フィルムを作製し、前記成形助剤除去フィルムを押出方向に延伸し、押出方向に延伸した後、押出方向と直交する方向に延伸して、延伸膜を作製し、当該延伸膜をＰＴＦＥの融点以上の温度で焼成して前記第１の積層ＰＴＦＥ多孔膜を製造することを特徴とする。 The second production method of the laminated PTFE porous membrane according to the present invention is to roll and dry the extruded product in the first production method of the laminated PTFE porous membrane to produce a forming aid removing film, and to form the forming aid removing film. In the extrusion direction, and then in the direction orthogonal to the extrusion direction to produce a stretched film, and the stretched film is fired at a temperature equal to or higher than the melting point of PTFE to obtain the first laminate. It is characterized by producing a PTFE porous membrane.
本発明に係る積層ＰＴＦＥ多孔膜の第３の製法は、前記積層ＰＴＦＥ多孔膜の第２の製法における成形助剤除去フィルムを作製した後、ニップロールにより狭圧して高密度未焼成フィルムを作製し、作製した前記高密度未焼成フィルムを押出方向に延伸し、押出方向に延伸した後、押出方向と直交する方向に延伸して、高密度延伸膜を作製し、当該高密度延伸膜をＰＴＦＥの融点以上の温度で焼成して請求項１に記載の積層ＰＴＦＥ多孔膜を製造することを特徴とする。 A third method for producing a laminated PTFE porous membrane according to the present invention is to prepare a molding aid-removing film in the second method for producing a laminated PTFE porous membrane, and then produce a high-density unbaked film by narrowing the pressure with a nip roll. The produced high-density unsintered film is stretched in the extrusion direction, stretched in the extrusion direction, and then stretched in a direction orthogonal to the extrusion direction to produce a high-density stretched film, and the high-density stretched film is melted at the melting point of PTFE. The laminated PTFE porous membrane according to claim 1 is manufactured by firing at the above temperature.
上記のように構成された積層ＰＴＦＥ多孔膜は、機械的強度が向上し、十分な耐水性、通気性及び粒子の捕集性能を有する。 The laminated PTFE porous membrane configured as described above has improved mechanical strength, sufficient water resistance, air permeability, and particle collection performance.
また、当該積層ＰＴＦＥ多孔膜は、静電気帯電の放電によるピンホールが減少する。 Further, in the laminated PTFE porous film, pinholes due to discharge of electrostatic charging are reduced.
さらに、当該積層ＰＴＦＥ多孔膜は、十分な厚みを確保できるので、外力による圧密を抑制する。完全一体化された膜単体となるので、剥離などが生じることがなく、取り扱い性が向上する。 Furthermore, since the laminated PTFE porous membrane can secure a sufficient thickness, it suppresses consolidation due to external force. Since the film is a completely integrated film, peeling does not occur and the handleability is improved.
さらにまた、当該積層ＰＴＦＥ多孔膜は、接着剤で他の布帛とラミネートするときに接着剤が当該積層ＰＴＦＥ多孔膜に吸収されて布帛の表面へ接着剤が染み出すおそれがない。 Furthermore, when the laminated PTFE porous film is laminated with another cloth by an adhesive, the adhesive is not absorbed by the laminated PTFE porous film and the adhesive does not seep out to the surface of the cloth.
また、当該積層ＰＴＦＥ多孔膜は、界面活性剤や皮脂などの接触による通気性の悪化を抑制する効果がある。 In addition, the laminated PTFE porous film has an effect of suppressing deterioration of air permeability due to contact with a surfactant or sebum.
積層ＰＴＦＥ多孔膜は、その厚み方向の層がＡ層（第１層）、Ｂ層（第２層）、Ｃ層（第３層）以上の多層からなる。 The laminated PTFE porous membrane has a multilayer structure including layers A (first layer), B (second layer), and C (third layer) in the thickness direction.
Ａ層とＣ層とは、フィブリルとノードによる多孔膜を形成し易いＰＴＦＥ乳化重合粒子のファインパウダーからなり、微細孔が形成された層である。Ａ層及びＣ層は、同一のＰＴＦＥ乳化重合粒子のファインパウダーであってもよいし、異なるＰＴＦＥ乳化重合粒子のファインパウダーであってもよい。Ａ層及びＣ層を形成するフィブリルとノードによる微細孔を形成し易いＰＴＦＥは、数平均分子量が３００万以上であるＰＴＦＥ乳化重合粒子から構成される。 The A layer and the C layer are layers in which fine particles of PTFE emulsion-polymerized particles that easily form a porous film composed of fibrils and nodes are formed, and in which fine pores are formed. The A layer and the C layer may be fine powders of the same PTFE emulsion-polymerized particles or may be fine powders of different PTFE emulsion-polymerized particles. PTFE, which easily forms fine pores due to the fibrils and nodes forming the A layer and C layer, is composed of PTFE emulsion-polymerized particles having a number average molecular weight of 3,000,000 or more.
Ｂ層は、Ａ層とＣ層との間に介在する中間層であって微細孔を形成していない層である。Ｂ層は膜の表面から見た構造が数ミリ単位の葉脈的筋状多角形状の構造の層が形成されている。また、Ｂ層は、共重合性変性剤が０．５％以下含まれ、フィブリル化が行われにくいＰＴＦＥ乳化重合粒子のファインパウダーから構成される。なお、共重合性変性剤としては、ヘキサフルオロプロペン、ω−ヒドロパーフルオロオレフィン、トリフルオロクロロエチレン、炭素数３〜１０のパーフルオロアルキルトリフルオロエチレンが好適に使用できる。 The B layer is an intermediate layer interposed between the A layer and the C layer, and is a layer in which no fine holes are formed. The layer B is a layer having a vein-like streak polygonal structure in terms of the structure seen from the surface of the membrane. Further, the layer B is composed of a fine powder of PTFE emulsion-polymerized particles which contains 0.5% or less of a copolymerizable modifier and is difficult to be fibrillated. As the copolymerizable modifier, hexafluoropropene, ω-hydroperfluoroolefin, trifluorochloroethylene, and perfluoroalkyltrifluoroethylene having 3 to 10 carbon atoms can be preferably used.
Ａ層、Ｂ層及びＣ層は、一度に予備成形の段階から層状に形成して、さらに圧延・乾燥されたフィルムから積層ＰＴＦＥ多孔膜が製造される。 The layer A, the layer B, and the layer C are formed into layers from the preforming step at a time, and the laminated PTFE porous membrane is manufactured from the film that is further rolled and dried.
前記積層ＰＴＦＥ多孔膜は、ＭＤ方向に５倍以上、ＴＤ方向に１０倍以上の延伸倍率で作製し、融点以上の温度で熱処理される。 The laminated PTFE porous film is produced at a draw ratio of 5 times or more in the MD direction and 10 times or more in the TD direction, and is heat-treated at a temperature of the melting point or higher.
積層ＰＴＦＥ多孔膜を作製する前に、未焼成フィルムをニップロールで高密度化したのち延伸してもよい。 Before producing the laminated PTFE porous membrane, the unbaked film may be densified with a nip roll and then stretched.
なお、上記のＡ層、Ｂ層及びＣ層の間やＡ層及びＣ層の外側に、他のＰＴＦＥ多孔膜を積層する構造にしてもよい。 It should be noted that another PTFE porous membrane may be laminated between the above A layer, B layer and C layer or outside the A layer and C layer.
［積層ＰＴＦＥ多孔膜の作製］
ＰＴＦＥ乳化重合粒子からなるファインパウダーＦ−１０６（ダイキン工業株式会社製）に成形助剤として溶剤アイソパーＨ（エクソンモービルコーポレーション製）を２２重量部混合した（以後、この混合物を「成形助剤添混入ＰＴＦＥ乳化重合粒子Ａ」と称す）。
[Preparation of laminated PTFE porous membrane]
Fine powder F-106 (manufactured by Daikin Industries, Ltd.) consisting of PTFE emulsion-polymerized particles was mixed with 22 parts by weight of solvent Isopar H (manufactured by ExxonMobil Corporation) as a molding aid (hereinafter, this mixture was mixed with “molding aid mixed”). This is referred to as "PTFE emulsion-polymerized particle A").
変性されたＰＴＦＥ乳化重合粒子からなるファインパウダーＦ−２０５（ダイキン工業株式会社製）に成形助剤として溶剤アイソパーＨ（エクソンモービルコーポレーション製）を２０重量部混合した（以後、この混合物を「成形助剤混入変性ＰＴＦＥ乳化重合粒子Ｂ」と称す。）。 Fine powder F-205 (manufactured by Daikin Industries, Ltd.) consisting of modified PTFE emulsion-polymerized particles was mixed with 20 parts by weight of solvent Isopar H (manufactured by ExxonMobil Corporation) as a molding aid (hereinafter, this mixture was referred to as "molding aid"). Referred to as agent-modified modified PTFE emulsion-polymerized particles B").
７０ｍｍ正方形からなるペースト押出シリンダーに挿入するために、上記特許文献３の製法により、上記成形助剤添混入ＰＴＦＥ乳化重合粒子ＡからなるＡ層及びＣ層と、上記成形助剤混入変性ＰＴＦＥ乳化重合粒子ＢからなるＢ層とを３分の１の比率で、Ａ、Ｂ、Ｃの順に、予備成形金型にＡ層及びＣ層が上下に、Ｂ層が中間に配置されるように充填して、複層予備成形体を作製した。 In order to insert into a paste extrusion cylinder consisting of a 70 mm square, by the manufacturing method of the above-mentioned Patent Document 3, layers A and C composed of the PTFE emulsion-polymerized particles A mixed with the molding aid and the modified PTFE emulsion-polymerized mixture containing the molding aid. The B layer composed of the particles B is packed at a ratio of 1/3 in the order of A, B, and C so that the A and C layers are vertically arranged in the preforming mold, and the B layer is arranged in the middle. Thus, a multilayer preform was produced.
押出成形金型はダイス出口、すなわちノズル部分の開口は２５０ｍｍ×２ｍｍの細幅の矩形状をなしており、前記複層予備成形体は、押出成形金型から押出されるシートが厚み方向に３層になるように押出成形金型に充填してシート状の押出成形体を作製した。 The extrusion die has a die outlet, that is, the opening of the nozzle portion has a rectangular shape with a narrow width of 250 mm×2 mm. In the multilayer preform, the sheet extruded from the extrusion die is 3 in the thickness direction. A sheet-shaped extrusion-molded body was prepared by filling the extrusion-molding die in layers to form a sheet.
押出成形金型によりペースト押出したシート状の押出成形体をカレンダロールにて２００μｍに圧延し、続いて、溶剤を加熱除去して成形助剤除去フィルムを作製した。 A sheet-shaped extrusion-molded body which was paste-extruded by an extrusion-molding die was rolled to 200 μm by a calender roll, and subsequently, the solvent was removed by heating to produce a molding aid removal film.
前記で作製した成形助剤除去フィルムを、３００℃のロール間で長さＭＤ方向に５倍延伸した、続いてテンター装置を用いて２００℃でＴＤ方向に２０倍延伸した。テンターの熱固定ゾーンは３８０℃であった。 The forming aid removal film produced above was stretched 5 times in the MD direction between rolls at 300° C., and subsequently stretched 20 times in the TD direction at 200° C. using a tenter device. The heat setting zone of the tenter was 380°C.
なお、成形助剤除去フィルムを、２本一対のロールから構成され、一方は金属製ロールであり、他方は金属製の軸芯にゴムを被覆したゴムロールからなるニップロールに挟み込んで圧縮することにより作製した厚みだけを縮小させた高密度化未焼成ＰＴＦＥフィルムを延伸して熱固定して積層ＰＴＦＥ多孔膜を作製してもよい。 In addition, the molding aid removing film is composed of two pairs of rolls, one of which is a metal roll and the other of which is sandwiched by a nip roll made of a rubber roll having a metal shaft core covered with rubber and compressed. The densified unsintered PTFE film whose thickness is reduced may be stretched and heat-set to produce a laminated PTFE porous membrane.
［積層ＰＴＦＥ多孔膜の物性］
積層ＰＴＦＥ多孔膜の重量測定については、積層ＰＴＦＥ多孔膜の中央部を５０ｍｍ正方形の型で裁断してサンプル５枚を作製し、その１枚ずつの重量を電子天秤（有効桁１０００分の１ｇ、アズワン株式会社製アズプロ電子天秤ＡＳＰ２１３）で秤量し、その平均値を積層ＰＴＦＥ多孔膜の１枚分の重量とした。
[Physical properties of laminated PTFE porous membrane]
Regarding the weight measurement of the laminated PTFE porous membrane, the central portion of the laminated PTFE porous membrane was cut with a 50 mm square mold to prepare five samples, and the weight of each sample was measured by an electronic balance (effective digit 1000 g, It was weighed with an Aspro electronic balance ASP213) manufactured by Asone Co., Ltd., and the average value was taken as the weight of one laminated PTFE porous membrane.
積層ＰＴＦＥ多孔膜の厚みは、ダイヤルシックネスゲージ（株式会社テクロック製ＳＭ−１１２でサンプル５枚分を重ねて測定し、その測定値を５で割った計算値を１枚分の厚みとした。その結果、積層ＰＴＦＥ多孔膜の１枚分の厚みは約３０μｍであった。 The thickness of the laminated PTFE porous film was measured by stacking five samples with a dial thickness gauge (SM-112 manufactured by Teclock Co., Ltd.), and dividing the measured value by 5 to obtain a thickness for one sheet. As a result, the thickness of one laminated PTFE porous membrane was about 30 μm.
また、ＭＤ・ＴＤ延伸後で焼結前にサンプルを作製し、粘着テープを両面に貼り付けて、図１に示すように、Ａ層とＣ層とを剥がして前記のマイクロメーターで測定した。その結果、元のＡ層〜Ｃ層の全厚みは３０μｍであり、Ａ層及びＣ層の厚みはそれぞれ約５μｍ、Ｂ層の厚みは約２０μｍであった。 Further, a sample was prepared after MD/TD stretching and before sintering, adhesive tapes were attached on both sides, and as shown in FIG. 1, the A layer and the C layer were peeled off and the measurement was carried out with the above-mentioned micrometer. As a result, the total thickness of the original layers A to C was 30 μm, the thicknesses of the layers A and C were about 5 μm, and the thickness of the layer B was about 20 μm.
積層ＰＴＦＥ多孔膜に対する気体の通過性は、実施例１の積層ＰＴＦＥ多孔膜の圧力損失と粒子の粒子除去効率を測定することにより算出した。 The gas permeability to the laminated PTFE porous membrane was calculated by measuring the pressure loss and particle removal efficiency of the laminated PTFE porous membrane of Example 1.
すなわち、圧力損失は、実施例１の積層ＰＴＦＥ多孔膜の測定サンプルを、内径１００ｍｍのフィルタホルダにセットし、コンプレッサで入口側を加圧し、流速計で空気の透過する流量を５．３ｃｍ／秒に調整した。そして、この時の圧力損失をマノメータで測定した。 That is, for the pressure loss, the measurement sample of the laminated PTFE porous membrane of Example 1 was set in a filter holder having an inner diameter of 100 mm, the inlet side was pressurized by a compressor, and the flow rate of air permeated by a velocity meter was 5.3 cm/sec. Adjusted to. Then, the pressure loss at this time was measured with a manometer.
また、捕集効率は、ＪＩＳ Ｂ９９２８ 附属書５（規定）ＮａＣｌエアロゾルの発生方法（加圧噴霧法）記載の方法に準じて、アトマイザーで発生させたＮａＣｌ粒子を、静電分級器（ＴＳＩ社製）で、粒子径０．１μｍに分級し、アメリシウム２４１を用いて粒子帯電を中和した後、透過する流量を５．３ｃｍ／秒に調整し、パーティクルカウンター（ＴＳＩ社製、ＣＮＣ）を用いて、測定試料である実施例１の積層ＰＴＦＥ多孔膜の前後での粒子数を求め、次式により捕集効率を算出した。 In addition, the collection efficiency is based on the method described in JIS B9928 Annex 5 (normative) NaCl aerosol generation method (pressurized spraying method), and the NaCl particles generated by the atomizer are treated with an electrostatic classifier (manufactured by TSI). ), the particle diameter was classified to 0.1 μm, and the particle charge was neutralized with americium 241. Then, the permeation flow rate was adjusted to 5.3 cm/sec, and a particle counter (TSI, CNC) was used. The number of particles before and after the laminated PTFE porous membrane of Example 1, which is a measurement sample, was determined, and the collection efficiency was calculated by the following equation.
ＣＯ＝測定試料が捕集したＮａＣｌ ０．１μｍの粒子数
ＣＩ＝測定試料に供給されたＮａＣｌ ０．１μｍの粒子数
捕集効率（％）＝（ＣＯ／ＣＩ）×１００
ＰＴＦＥ多孔膜の特性としては、圧力損失及び捕集効率が重要であるが、この２つの特性は、一方を上げれば他方が下がる傾向を有しているので、その両立が難しい。圧力損失と捕集効率とのバランスの優劣を評価するための指標としては次式で求められるＰＦ値が用いられる。
CO=number of particles of NaCl 0.1 μm collected by the measurement sample CI=number of particles of NaCl 0.1 μm supplied to the measurement sample Collection efficiency (%)=(CO/CI)×100
Pressure loss and trapping efficiency are important as the characteristics of the PTFE porous membrane, but it is difficult to satisfy both of these characteristics because one of them tends to decrease and the other decreases. The PF value obtained by the following equation is used as an index for evaluating the superiority or inferiority of the balance between the pressure loss and the collection efficiency.
ＰＦ値＝｛−ｌｏｇ（（１００−捕集効率（％））／１００）｝／（圧力損失／１０００）
その試験結果は以下の表１に示すとおりである。
PF value={-log((100-collection efficiency (%))/100)}/(pressure loss/1000)
The test results are shown in Table 1 below.
積層ＰＴＦＥ多孔膜の孔径の測定については、表１に示される０．１μｍのＮａＣｌ粒子がほぼ１００％捕集されていることから、Ａ層及びＣ層の孔径は、概ね０．１μｍ程度であると推定できた。 Regarding the measurement of the pore diameter of the laminated PTFE porous membrane, since the NaCl particles of 0.1 μm shown in Table 1 are almost 100% collected, the pore diameter of the A layer and the C layer is about 0.1 μm. It was possible to estimate.
Ｂ層については、図２に示すように、実体写真から１ｃｍ２を選んでその重さを測定し、比較的小さな孔径になる部分と比較的大きな孔径となる部分とを切り抜いて、その重さを測定し、その重さを面積に換算した。そして、その面積を円の面積として孔径を算出した。その結果は、下記表２に示すとおりであり、Ｂ層の孔径は概ね２２μｍ〜１２０μｍであると推定できた。 As for the layer B, as shown in FIG. 2, 1 cm 2 was selected from the stereoscopic photograph and its weight was measured, and a portion having a relatively small hole diameter and a portion having a relatively large hole diameter were cut out and the weight thereof was measured. Was measured and the weight was converted into an area. Then, the pore size was calculated with the area as the area of the circle. The results are shown in Table 2 below, and it could be estimated that the pore size of the B layer was approximately 22 μm to 120 μm.
積層ＰＴＦＥ多孔膜の流体浸透性については、積層ＰＴＦＥ多孔膜の下に色紙を敷き、エクストラバージンオリーブオイル７０ｇ入り（株式会社Ｊ-オイルミルズ製、味の素販売）を使用してオリーブオイルを積層ＰＴＦＥ多孔膜に一滴（約０．０２５ｇ）滴下して測定した。まず、オリーブオイル滴下前の前記色紙の重量を測定し、オリーブオイル滴下１０分後の色紙の重量を測定して、その差を浸透量とした。 Regarding the fluid permeability of the laminated PTFE porous membrane, a colored paper is laid under the laminated PTFE porous membrane, and extra virgin olive oil (70 g) (J-Oil Mills Co., Ltd., Ajinomoto Co., Inc.) is used to laminate the olive oil with the laminated PTFE porous membrane. The measurement was performed by dropping one drop (about 0.025 g) on the film. First, the weight of the colored paper before dropping of olive oil was measured, and the weight of the colored paper after 10 minutes of dropping of olive oil was measured, and the difference was defined as the permeation amount.
［比較例１］
比較例１として、成形助剤添混入ＰＴＦＥ乳化重合粒子Ａのみからなる多孔膜を、実施例１と同様の製法でペースト押出、圧延、二軸延伸で多孔膜を作製した。
[Comparative Example 1]
As Comparative Example 1, a porous film made of only PTFE emulsion-polymerized particles A mixed with a molding aid was prepared by the same production method as in Example 1 by paste extrusion, rolling, and biaxial stretching to produce a porous film.
［比較例２］
比較例２として、厚み１５μｍの比較例１の多孔膜を２枚重ねて厚み３０μｍした多孔膜を作製した。
[Comparative example 2]
As Comparative Example 2, a porous film having a thickness of 30 μm was produced by stacking two porous films of Comparative Example 1 having a thickness of 15 μm.
［試験結果］
実施例１、比較計１及び比較例２について、上記した測定を行ったところ、下記表３の結果となった。
[Test results]
When the above-described measurement was performed for Example 1, Comparative Example 1 and Comparative Example 2, the results shown in Table 3 below were obtained.
上記表３に示されるように、実施例１は、比較例１と重量において差がほとんどないが、厚みにおいては実施例１の方が２倍になった。 As shown in Table 3 above, Example 1 showed almost no difference in weight from Comparative Example 1, but the thickness of Example 1 was doubled.
また、浸透試験を行った結果、図３に示すように、実施例１の多孔膜と比較例１の多孔膜にオリーブオイルを滴下したところ、図４に示すように、色紙に対して実施例１は浸透量が目に見えて僅かであり、比較例１の浸透量は多かった。数値的には、表３に示すように実施例１の浸透量が非常に少ない結果になった。 Further, as a result of the penetration test, as shown in FIG. 3, when olive oil was dropped on the porous membrane of Example 1 and the porous membrane of Comparative Example 1, as shown in FIG. In Example 1, the permeation amount was visibly small, and in Comparative Example 1, the permeation amount was large. Numerically, as shown in Table 3, the amount of penetration of Example 1 was extremely small.
さらに、図５に示すように、比較例２の多孔膜にオリーブオイルを滴下すると、１０分経過後には図６に示すような状態となり、色紙に対しては、図７及び表３に示すように、に示すように、浸透量は比較例１と大した差がなく、比較例１の多孔膜を２枚重ねた場合も浸透量はかなり大きいことが解った。また、浸透速度は比較例１の１枚の場合と変わらなかった。つまり単純に厚みのよっては浸透量も浸透速度も変わらないことが判った。 Further, as shown in FIG. 5, when olive oil was dropped on the porous membrane of Comparative Example 2, the state shown in FIG. 6 was obtained after 10 minutes, and for colored paper, as shown in FIG. 7 and Table 3. As shown in (1) and (2), the permeation amount was not significantly different from that of Comparative Example 1, and it was found that the permeation amount was considerably large even when two porous membranes of Comparative Example 1 were stacked. The permeation rate was the same as that of the single sheet of Comparative Example 1. In other words, it was found that the permeation amount and permeation rate did not change simply depending on the thickness.
以上のことから、実施例１のＢ層、すなわち成形助剤混入変性ＰＴＦＥ乳化重合粒子Ｂから構成された多孔膜層は、空間層となり液を捕集して浸透を遮断する効果が確認された。 From the above, it was confirmed that the layer B of Example 1, that is, the porous membrane layer composed of the modified PTFE emulsion-polymerized particles B mixed with the molding aid became the space layer and has the effect of collecting the liquid and blocking the permeation. ..
以上、本発明の実施形態を説明したが、この実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。この実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。この実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope of the invention and the scope thereof, as well as in the scope of the invention described in the claims and the scope of equivalents thereof.
本発明に係る第１の積層ＰＴＦＥ多孔膜は、第１層〜第３層の３つの層を含む３層以上の積層体から構成され、第１層及び第３層は、数平均分子量が３００万以上のＰＴＦＥ乳化重合粒子により作製され、フィブリルとノードとにより形成された微細孔を有するＰＴＦＥ多孔膜層であり、第２層は、第１層と第３層との間に位置し、共重合性変性剤を含んだＰＴＦＥ乳化重合粒子により作製された難フィブリル化の変性ＰＴＦＥ多孔膜層であって、ノードにより形成された大きな孔径を有する変性ポリテトラフルオロエチレン多孔膜層であることを特徴とする。 The first laminated PTFE porous membrane according to the present invention is composed of a laminated body of three or more layers including three layers of a first layer to a third layer, and the first layer and the third layer have a number average molecular weight of 300. Is a PTFE porous membrane layer made of 10,000 or more PTFE emulsion-polymerized particles and having micropores formed by fibrils and nodes, the second layer being located between the first layer and the third layer, I modified PTFE porous film layer der poorly fibrillated made by PTFE emulsion polymerization particles containing polymerizable modifier, modified polytetrafluoroethylene porous membrane layer der Rukoto having a large pore size formed by the node Is characterized by.
本発明に係る第２の積層ＰＴＦＥ多孔膜は、前記第１の積層ＰＴＦＥ多孔膜の構成に加えて、第１層と第３層のポリテトラフルオロエチレン多孔膜層の孔径は、第２層の変性ポリテトラフルオロエチレン多孔膜層の孔径よりも小であることを特徴とする。 The second laminated PTFE porous membrane according to the present invention has, in addition to the structure of the first laminated PTFE porous membrane, a pore diameter of the polytetrafluoroethylene porous membrane layers of the first layer and the third layer, that of the second layer. It is characterized by being smaller than the pore diameter of the modified polytetrafluoroethylene porous membrane layer .
本発明に係る第３の積層ＰＴＦＥ多孔膜は、前記第１又は第２の積層ＰＴＦＥ多孔膜の構成に加えて、第１層と第３層のポリテトラフルオロエチレン多孔膜層の厚みは、第２層の変性ポリテトラフルオロエチレン多孔膜層の厚みより小であることを特徴とする。 In addition to the configuration of the first or second laminated PTFE porous membrane, the third laminated PTFE porous membrane according to the present invention has the first and third polytetrafluoroethylene porous membrane layers each having a thickness of It is characterized by being smaller than the thickness of the two modified polytetrafluoroethylene porous membrane layers .
本発明に係る積層ＰＴＦＥ多孔膜の第１の製法は、前記第１の積層ＰＴＦＥ多孔膜における第１層を形成するための成形助剤添混入ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第２層を形成するための成形助剤混入変性ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第３層を形成するための成形助剤混入ＰＴＦＥ乳化重合粒子とを、第１層、第２層、第３層の順序に積層して予備成形体を作製し、当該予備成形体を押出成形金型に装填し、装填した前記予備成形体を当該押出成形金型から押し出して押出成形体を作製し、前記押出成形体を圧延及び乾燥して成形助剤除去フィルムを作製し、前記成形助剤除去フィルムを押出方向に５倍以上延伸し、押出方向に延伸した後、押出方向と直交する方向に２０倍以上延伸して、延伸膜を作製し、当該延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して請求項１〜３のいずれか１項に記載の積層ポリテトラフルオロエチレン多孔膜を製造することを特徴とする。 A first method for producing a laminated PTFE porous membrane according to the present invention is a step of forming a first layer in the first laminated PTFE porous membrane, wherein the PTFE emulsion-polymerized particles mixed with a molding aid are mixed with the first laminated PTFE porous membrane. Modified PTFE emulsion-polymerized particles mixed with a molding aid for forming the second layer in the membrane, and PTFE emulsion-polymerized particles mixed with a molding aid for forming the third layer in the first laminated PTFE porous membrane, A preform is prepared by laminating the first layer, the second layer, and the third layer in this order, the preform is loaded into an extrusion mold, and the loaded preform is extruded from the extrusion mold. To produce an extrusion molded article, roll and dry the extrusion molded article to produce a molding aid removal film, stretch the molding aid removal film 5 times or more in the extrusion direction, and then stretch in the extrusion direction, was stretched 20 times in the direction perpendicular to the extrusion direction, to produce a drawn film, according to any one of claims 1 to 3 by sintering the stretched film at a temperature above the melting point of polytetrafluoroethylene It is characterized by producing a laminated polytetrafluoroethylene porous membrane.
本発明に係る積層ＰＴＦＥ多孔膜の第２の製法は、前記積層ＰＴＦＥ多孔膜の第１の製法における成形助剤除去フィルムを作製した後、当該成形助剤除去フィルムを、２本一対のロールから構成され、一方は金属製ロールであり、他方は金属製の軸芯にゴムを被覆したゴムロールからなるニップロールにより狭圧して高密度未焼成フィルムを作製し、作製した前記高密度未焼成フィルムを押出方向に５倍以上延伸し、押出方向に延伸した後、押出方向と直交する方向に２０倍以上延伸して、高密度延伸膜を作製し、当該高密度延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して請求項１〜３のいずれか１項に記載の積層ポリテトラフルオロエチレン多孔膜を製造することを特徴とする。 The second method for producing the laminated PTFE porous membrane according to the present invention is to prepare the forming aid removing film in the first producing method for the laminated PTFE porous membrane, and then form the forming aid removing film from a pair of two rolls. Configured, one is a metal roll, the other is a high-density unfired film is narrowed by a nip roll consisting of a rubber roll coated with rubber on a metal shaft core to produce a high-density unfired film, and the produced high-density unfired film is extruded After stretching 5 times or more in the direction, stretching in the extrusion direction, and then stretching 20 times or more in the direction orthogonal to the extrusion direction, a high density stretched film is produced, and the high density stretched film has a melting point of polytetrafluoroethylene or higher. The laminated polytetrafluoroethylene porous membrane according to any one of claims 1 to 3 is manufactured by firing at the temperature of.
［積層ＰＴＦＥ多孔膜の作製］
ＰＴＦＥ乳化重合粒子からなるファインパウダーＦ−１０６（ダイキン工業株式会社製）に成形助剤として溶剤アイソパーＨ（エクソンモービルコーポレーション製）を２２重量部混合した（以後、この混合物を「成形助剤混入ＰＴＦＥ乳化重合粒子Ａ」と称す）。
[Preparation of laminated PTFE porous membrane]
Fine powder F-106 (manufactured by Daikin Industries, Ltd.) composed of PTFE emulsion-polymerized particles was mixed with 22 parts by weight of solvent Isopar H (manufactured by ExxonMobil Corporation) as a molding aid (hereinafter, this mixture was referred to as " molding aid mixed PTFE"). Emulsion polymer particles A").
［比較例１］
比較例１として、成形助剤混入ＰＴＦＥ乳化重合粒子Ａのみからなる多孔膜を、実施例１と同様の製法でペースト押出、圧延、二軸延伸で多孔膜を作製した。
[Comparative Example 1]
As Comparative Example 1, a porous film composed only of PTFE emulsion-polymerized particles A mixed with a molding aid was prepared by the same production method as in Example 1 by paste extrusion, rolling and biaxial stretching to prepare a porous film.
［比較例２］
比較例２として、厚み１５μｍの比較例１の多孔膜を２枚重ねて厚み３０μｍの多孔膜を作製した。
[Comparative example 2]
As Comparative Example 2, two porous films of Comparative Example 1 having a thickness of 15 μm were stacked to form a porous film having a thickness of 30 μm .
さらに、図５に示すように、比較例２の多孔膜にオリーブオイルを滴下すると、１０分経過後には図６に示すような状態となり、色紙に対しては、図７及び表３に示すように、浸透量は比較例１と大した差がなく、比較例１の多孔膜を２枚重ねた場合も浸透量はかなり大きいことが解った。また、浸透速度は比較例１の１枚の場合と変わらなかった。つまり単純に厚みによっては浸透量も浸透速度も変わらないことが判った。 Furthermore, as shown in FIG. 5, when dropping a porous membrane olive oil of Comparative Example 2, after lapse of 10 minutes in a state as shown in FIG. 6, for the color paper, as shown in FIG. 7 and Table 3 In addition, the permeation amount was not so different from that of Comparative Example 1, and it was found that the permeation amount was considerably large even when two porous membranes of Comparative Example 1 were stacked. The permeation rate was the same as that of the single sheet of Comparative Example 1. In other words, it was found that the permeation amount and permeation rate simply did not change depending on the thickness .
本発明に係る第１の積層ＰＴＦＥ多孔膜は、第１層〜第３層の３つの層を含む３層以上の積層体から構成され、第１層及び第３層は、数平均分子量が３００万以上のポリテトラフルオロエチレン乳化重合粒子により作製され、フィブリルとノードとにより形成された微細孔を有するポリテトラフルオロエチレン多孔膜層であり、第２層は、第１層と第３層との間に位置し、共重合性変性剤を含んだポリテトラフルオロエチレン乳化重合粒子により作製された難フィブリル化の変性ポリテトラフルオロエチレン多孔膜層であって、ノードにより形成され、第１層及び第３層に形成された微細孔よりも大きな孔径を有する変性ポリテトラフルオロエチレン多孔膜層であることを特徴とする。 The first laminated PTFE porous membrane according to the present invention is composed of a laminated body of three or more layers including three layers of a first layer to a third layer, and the first layer and the third layer have a number average molecular weight of 300. It is a polytetrafluoroethylene porous membrane layer made of 10,000 or more polytetrafluoroethylene emulsion-polymerized particles and having fine pores formed by fibrils and nodes, and the second layer is composed of a first layer and a third layer. A modified polytetrafluoroethylene porous membrane layer which is located between and which is made of polytetrafluoroethylene emulsion-polymerized particles containing a copolymerizable modifier and which is difficult to fibrillate and which is formed by a node and has a first layer and a second layer. It is a modified polytetrafluoroethylene porous membrane layer having a pore size larger than the micropores formed in the three layers .
本発明に係る第２の積層ＰＴＦＥ多孔膜は、前記第１の積層ＰＴＦＥ多孔膜の構成に加えて、第１層と第３層のポリテトラフルオロエチレン多孔膜層の厚みは、第２層の変性ポリテトラフルオロエチレン多孔膜層の厚みより小であることを特徴とする。 The second laminated PTFE porous membrane according to the present invention has, in addition to the constitution of the first laminated PTFE porous membrane, a thickness of the polytetrafluoroethylene porous membrane layer of the first layer and the third layer is equal to that of the second layer. It is characterized by being smaller than the thickness of the modified polytetrafluoroethylene porous membrane layer.
本発明に係る積層ＰＴＦＥ多孔膜の第１の製法は、前記第１の積層ＰＴＦＥ多孔膜における第１層を形成するための成形助剤添混入ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第２層を形成するための成形助剤混入変性ＰＴＦＥ乳化重合粒子と、前記第１の積層ＰＴＦＥ多孔膜における第３層を形成するための成形助剤混入ＰＴＦＥ乳化重合粒子とを、第１層、第２層、第３層の順序に積層して予備成形体を作製し、当該予備成形体を押出成形金型に装填し、装填した前記予備成形体を当該押出成形金型から押し出して押出成形体を作製し、前記押出成形体を圧延及び乾燥して成形助剤除去フィルムを作製し、前記成形助剤除去フィルムを押出方向に５倍以上延伸し、押出方向に延伸した後、押出方向と直交する方向に２０倍以上延伸して、延伸膜を作製し、当該延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して前記第１又は第２の積層ポリテトラフルオロエチレン多孔膜を製造することを特徴とする。 A first method for producing a laminated PTFE porous membrane according to the present invention is a step of forming a first layer in the first laminated PTFE porous membrane, wherein the PTFE emulsion-polymerized particles mixed with a molding aid are mixed with the first laminated PTFE porous membrane. Modified PTFE emulsion-polymerized particles mixed with a molding aid for forming the second layer in the membrane, and PTFE emulsion-polymerized particles mixed with a molding aid for forming the third layer in the first laminated PTFE porous membrane. A preform is prepared by laminating the first layer, the second layer, and the third layer in this order, the preform is loaded into an extrusion mold, and the loaded preform is extruded from the extrusion mold. To produce an extrusion molded article, roll and dry the extrusion molded article to produce a molding aid removal film, stretch the molding aid removal film 5 times or more in the extrusion direction, and then stretch in the extrusion direction, The stretched film is produced by stretching the stretched film 20 times or more in a direction orthogonal to the extrusion direction, and the stretched film is fired at a temperature equal to or higher than the melting point of polytetrafluoroethylene to obtain the first or second laminated polytetrafluoroethylene porous film. It is characterized by producing a membrane.
本発明に係る積層ＰＴＦＥ多孔膜の第２の製法は、前記積層ＰＴＦＥ多孔膜の第１の製法における成形助剤除去フィルムを作製した後、当該成形助剤除去フィルムを、２本一対のロールから構成され、一方は金属製ロールであり、他方は金属製の軸芯にゴムを被覆したゴムロールからなるニップロールにより狭圧して高密度未焼成フィルムを作製し、作製した前記高密度未焼成フィルムを押出方向に５倍以上延伸し、押出方向に延伸した後、押出方向と直交する方向に２０倍以上延伸して、高密度延伸膜を作製し、当該高密度延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して前記第１又は第２の積層ポリテトラフルオロエチレン多孔膜を製造することを特徴とする。 The second method for producing a laminated PTFE porous membrane according to the present invention is to prepare the forming aid removing film in the first producing method for the laminated PTFE porous membrane, and then form the forming aid removing film from a pair of two rolls. Configured, one is a metal roll, the other is a high-density unfired film is narrowed by a nip roll consisting of a rubber roll coated with rubber on a metal shaft core to produce a high-density unfired film, and the produced high-density unfired film is extruded After stretching 5 times or more in the direction, stretching in the extrusion direction, and then stretching 20 times or more in the direction orthogonal to the extrusion direction, a high density stretched film is produced, and the high density stretched film has a melting point of polytetrafluoroethylene or higher. It is characterized in that the first or second laminated polytetrafluoroethylene porous membrane is manufactured by firing at the temperature of.
Claims (5)
第１層及び第３層は、数平均分子量が３００万以上のポリテトラフルオロエチレン乳化重合粒子により作製され、フィブリルとノードとにより形成された微細孔を有するポリテトラフルオロエチレン多孔膜層であり、
第２層は、第１層と第３層との間に位置し、共重合性変性剤を含んだポリテトラフルオロエチレン乳化重合粒子により作製された難フィブリル化の変性ポリテトラフルオロエチレン多孔膜層である
ことを特徴とする積層ポリテトラフルオロエチレン多孔膜。 It is composed of a laminate of three or more layers including three layers of the first layer to the third layer,
The first layer and the third layer are polytetrafluoroethylene porous membrane layers each having a number average molecular weight of 3,000,000 or more and made of polytetrafluoroethylene emulsion-polymerized particles, and having fine pores formed by fibrils and nodes,
The second layer is located between the first layer and the third layer, and is a fibrillated modified polytetrafluoroethylene porous membrane layer made of polytetrafluoroethylene emulsion-polymerized particles containing a copolymerizable modifier. A laminated polytetrafluoroethylene porous membrane characterized by being:
ことを特徴とする請求項１に記載の積層ポリテトラフルオロエチレン多孔膜。 The copolymerizable modifier comprises at least one selected from hexafluoropropene, ω-hydroperfluoroolefin, trifluorochloroethylene, and perfluoroalkyltrifluoroethylene having 3 to 10 carbon atoms. The laminated polytetrafluoroethylene porous membrane according to claim 1.
当該予備成形体を押出成形金型に装填し、
装填した前記予備成形体を当該押出成形金型から押し出して押出成形体を作製し、
前記押出成形体から請求項１に記載の積層ポリテトラフルオロエチレン多孔膜を製造する
ことを特徴とする積層ポリテトラフルオロエチレン多孔膜の製法。 A molding aid-added polytetrafluoroethylene emulsion-polymerized particle for forming the first layer according to claim 1, and a molding aid-containing modified polytetrafluoro for forming the second layer according to claim 1. Ethylene emulsion-polymerized particles and polytetrafluoroethylene emulsion-polymerized particles mixed with a molding aid for forming the third layer according to claim 1 are laminated in the order of a first layer, a second layer and a third layer. To make a preform,
Load the preform into an extrusion mold,
Extruding the loaded preform from the extrusion mold to produce an extrudate,
A method for producing a laminated polytetrafluoroethylene porous membrane, comprising producing the laminated polytetrafluoroethylene porous membrane according to claim 1 from the extruded body.
前記成形助剤除去フィルムを押出方向に延伸し、
押出方向に延伸した後、押出方向と直交する方向に延伸して、延伸膜を作製し、
当該延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して請求項１に記載の積層ポリテトラフルオロエチレン多孔膜を製造する
ことを特徴とする積層ポリテトラフルオロエチレン多孔膜の製法。 The extruded product according to claim 3 is rolled and dried to produce a film forming agent removal film,
Stretching the molding aid removal film in the extrusion direction,
After stretching in the extrusion direction, stretching in a direction orthogonal to the extrusion direction to produce a stretched film,
A method for producing a laminated polytetrafluoroethylene porous membrane, comprising: firing the stretched membrane at a temperature equal to or higher than a melting point of polytetrafluoroethylene to produce the laminated polytetrafluoroethylene porous membrane according to claim 1.
ニップロールにより狭圧して高密度未焼成フィルムを作製し、
作製した前記高密度未焼成フィルムを押出方向に延伸し、
押出方向に延伸した後、押出方向と直交する方向に延伸して、高密度延伸膜を作製し、
当該高密度延伸膜をポリテトラフルオロエチレンの融点以上の温度で焼成して請求項１に記載の積層ポリテトラフルオロエチレン多孔膜を製造する
ことを特徴とする積層ポリテトラフルオロエチレン多孔膜の製法。 After producing the forming aid removal film according to claim 4,
Narrow roll is used to narrow the pressure to produce a high-density unbaked film,
Stretching the produced high-density unbaked film in the extrusion direction,
After stretching in the extrusion direction, stretching in a direction orthogonal to the extrusion direction to produce a high-density stretched film,
A method for producing a laminated polytetrafluoroethylene porous membrane, comprising: firing the high-density stretched membrane at a temperature equal to or higher than a melting point of polytetrafluoroethylene to produce the laminated polytetrafluoroethylene porous membrane according to claim 1.
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| WO2013157647A1 (en) * | 2012-04-20 | 2013-10-24 | ダイキン工業株式会社 | Composition mainly composed of ptfe, mixed powder, molding material, filtering medium for filter, air filter unit, and porous membrane manufacturing method |
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