JP2016052733A5

JP2016052733A5 -

Info

Publication number: JP2016052733A5
Application number: JP2014179103A
Authority: JP
Filing date: 2014-09-03
Publication date: 2017-10-12
Anticipated expiration: 2034-09-03

Description

本発明にかかる多孔質膜の製造方法は、フッ素樹脂を含む多孔質膜からなる第１の層と、多孔質膜からなる第２の層とを有する多孔質膜の製造方法であって、
前記第１の層形成用の多孔質膜と、前記第２の層形成用の多孔質膜とを積層して積層体を形成する工程と、
前記積層体の第１の層形成用の多孔質膜側の表面に、圧接部材の押圧面を加熱下で押し当てて、該積層体の各多孔質膜の積層面を熱圧着する工程と、
を有し、
前記圧接部材の押圧面の算術平均粗さ（Ｒａ）が、該押圧面が圧接される前記第１の層形成用の多孔質膜の表面の算術平均粗さ（Ｒａ）よりも小さく、かつ、
前記圧接部材の圧縮弾性率が前記第１の層形成用の多孔質膜の圧縮弾性率より大きい、
ことを特徴とする。 A method for producing a porous film according to the present invention is a method for producing a porous film having a first layer made of a porous film containing a fluororesin and a second layer made of a porous film,
Laminating the porous film for forming the first layer and the porous film for forming the second layer to form a laminate;
A step of pressing the pressing surface of the pressure contact member to the surface on the porous film side for forming the first layer of the laminated body under heating, and thermocompression bonding the laminated surface of each porous film of the laminated body;
Have
The arithmetic average roughness (Ra) of the pressing surface of the pressing member is smaller than the arithmetic average roughness (Ra) of the surface of the porous film for forming the first layer to which the pressing surface is pressed, and
The compression elastic modulus of the pressure contact member is larger than the compression elastic modulus of the porous film for forming the first layer,
It is characterized by that.

本発明者らは、上述したような熱圧ラミネート工程に用いる第１の圧接部材の押圧面の平滑性や圧接部材の強度に関して検討を重ねた。その結果、以下の式（１）及び（２）を満たす条件での熱圧ラミネートを行うことで、第１の層形成用の多孔質膜の表面の平滑性の劣化を抑制出来ることが分かった。すなわち、本発明においては、押圧面の平滑性が第１の多孔質膜の表面（露出面）よりも高く、かつ剛性が第１の層形成用の多孔質膜よりも高い圧接部材を用いている。その結果、熱圧ラミネート工程を経て得られる多孔質膜の第１の層の表面（露出面）に目的とする平滑性を制御性良く付与することが可能となる。
式（１）について、Ｒａ_{（ＲＳ１）}とＲａ_{（ＰＭ１）}の差は特に限定されることはないが、０．１μｍ以上であることが好ましい。式（２）について、Ｅ_{（ＲＳ１）}とＥ_{（ＰＭ１）}の差は特に限定されることはないが、１００MPa以上であることが好ましい。
（i）Ｒａ_{（ＲＳ１）}＜Ｒａ_{（ＰＭ１）}（式１）
Ｒａ_{（ＲＳ１）}：第１の圧接部材の押圧面の算術平均粗さ
Ｒａ_{（ＰＭ１）}：第１の圧接部材の押圧面が圧接される第１の層形成用の多孔質膜の表面（露出面）の算術平均粗さ
（ii）Ｅ_{（ＲＳ１）}＞Ｅ_{（ＰＭ１）}（式２）
Ｅ_{（ＲＳ１）}：第１の圧接部材の圧縮弾性率
Ｅ_{（ＰＭ１）}：第１の層形成用の多孔質膜の圧縮弾性率
なお、表面の平滑性は、ＪＩＳＢ０６０１：２０１１で規定される算術平均粗さＲａで評価することができ、Ｒａが小さい程、平滑性が高いことを示す。また、圧縮弾性率は、ＪＩＳＫ７１８１：２０１１で規定される値である。 The inventors have repeatedly studied the smoothness of the pressing surface of the first pressure contact member used in the hot-pressure laminating process and the strength of the pressure contact member. As a result, it was found that deterioration of the smoothness of the surface of the porous film for forming the first layer can be suppressed by performing hot-press lamination under conditions satisfying the following expressions (1) and (2). . That is, in the present invention, a pressure contact member having a smoothness of the pressing surface higher than the surface (exposed surface) of the first porous membrane and a rigidity higher than that of the porous membrane for forming the first layer is used. Yes. As a result, the target smoothness can be imparted with good controllability to the surface (exposed surface) of the first layer of the porous film obtained through the hot-press laminating step.
Regarding formula (1), the difference between Ra _(RS1) and Ra _(PM1) is not particularly limited, but is preferably 0.1 μm or more. Regarding Formula (2), the difference between E _(RS1) and E _(PM1) is not particularly limited, but is preferably 100 MPa or more.
(I) Ra _(RS1) <Ra _(PM1) (Formula 1)
Ra _(RS1) : Arithmetic mean roughness of the pressing surface of the first pressure contact member Ra _(PM1) : Surface of the porous film for forming the first layer on which the pressing surface of the first pressure contact member is pressed (exposed surface) ) Arithmetic average roughness (ii) E _(RS1) > E _(PM1) (Formula 2)
E _(RS1) : Compression elastic modulus of the first pressure contact member E _(PM1) : Compression elastic modulus of the porous film for forming the first layer The surface smoothness is defined by JIS B 0601: 2011. The arithmetic average roughness Ra can be evaluated, and the smaller Ra is, the higher the smoothness is. The compression elastic modulus is a value specified by JIS K 7181: 2011.

第２の層の表面（露出面）の算術平均粗さ（Ｒａ）は５０μｍ以下であることが好ましい。なお、この露出面の算術平均粗さ（Ｒａ）の下限値は特に限定されないが、０．５μｍ程度に設定することができる。
第２の層の厚さは、３００μｍ以下であることが好ましい。なお、この厚さの下限値は特に限定されないが、１０μｍ程度に設定することができる。また、第２の層の厚さを、第１の層よりも大きくすることが好ましい。
第２の層の平均繊維径は０．１μｍ以上１５．０μｍ以下であることが好ましい。この平均繊維径は、０．１μｍ以上１０．０μｍ以下であることがより好ましい。また、第２の層の耐水圧は、第１の層よりも低いことが好ましい。 The arithmetic average roughness (Ra) of the surface (exposed surface) of the second layer is preferably 50 μm or less. The lower limit value of the arithmetic average roughness (Ra) of the exposed surface is not particularly limited, but can be set to about 0.5 μm.
The thickness of the second layer is preferably 300 μm or less. The lower limit of the thickness is not particularly limited, but can be set to about 10 μm. In addition, the thickness of the second layer is preferably larger than that of the first layer.
The average fiber diameter of the second layer is preferably 0.1 μm or more and 15.0 μm or less. The average fiber diameter is more preferably 0.1 μm or more and 10.0 μm or less. Further, the water pressure resistance of the second layer is preferably lower than that of the first layer.

本発明においては、熱圧ラミネート後に第１の層の表面となる多孔質膜の表面よりも高い平滑性の押圧面を有し、この多孔質膜よりも小さい圧縮弾性率を有し、かつ剛性の高い第１の圧接部材が用いられる。このことにより、熱圧ラミネート時における多孔質膜の表面における平滑性の低下を防止することができ、また、場合によっては平滑性の向上を図ることができる。その結果、熱圧ラミネートにより得られる多孔質膜を拭き取り部材として用いた場合における被清掃面からの付着物の拭き取ムラを無くすことが可能となる。
更に、第１の圧接部材と対向する位置に第２の圧接部材を配置して、これらの部材間にニップ部を形成し、このニップ部において上記の熱圧着工程を行うことができる。この第２の圧接部材は、熱圧ラミネート前の積層体に含まれる第２の層形成用の多孔質膜側に設けられ、その押圧面は第２の層形成用の多孔質膜の露出面に圧接される。この第２の圧接部材の圧縮弾性率及びその押圧面の算術平均粗さは、第２の層形成用の多孔質膜に対して以下の式（３）及び（４）で規定される関係を満たすように設定されることが好ましい。
式（３）について、Ｒａ_{（ＲＳ２）}とＲａ_{（ＰＭ２）}の差は特に限定されることはないが、０．１μｍ以上であることが好ましい。式（４）について、Ｅ_{（ＲＳ2）}とＥ_{（ＰＭ2）}の差は特に限定されることはないが、１００MPa以上であることが好ましい。
（i）Ｒａ_{（ＲＳ２）}＜Ｒａ_{（ＰＭ２）}（式３）
Ｒａ_{（ＲＳ２）}：第２の圧接部材の押圧面の算術平均粗さ
Ｒａ_{（ＰＭ２）}：第２の圧接部材の押圧面が圧接される第２の層形成用の多孔質膜の表面（露出面）の算術平均粗さ
（ii）Ｅ_{（ＲＳ２）}＞Ｅ_{（ＰＭ２）}（式４）
Ｅ_{（ＲＳ２）}：第２の圧接部材の圧縮弾性率
Ｅ_{（ＰＭ２）}：第２の層形成用の多孔質膜の圧縮弾性率
なお、この第２の圧接部材の有する第２の層形成用の多孔質膜への押圧面の算術平均粗さ（Ｒａ）は１．５μｍより小さいことが好ましい。 In the present invention, it has a pressing surface having a smoothness higher than the surface of the porous film that becomes the surface of the first layer after hot-press lamination, has a smaller compression elastic modulus than this porous film, and is rigid. A high pressure contact member is used. As a result, it is possible to prevent a decrease in smoothness on the surface of the porous film during hot-press lamination, and it is possible to improve the smoothness in some cases. As a result, it is possible to eliminate unevenness in wiping off deposits from the surface to be cleaned when a porous film obtained by hot-press lamination is used as a wiping member.
Further, the second pressure contact member is disposed at a position facing the first pressure contact member, a nip portion is formed between these members, and the above-described thermocompression bonding process can be performed at the nip portion. The second pressure contact member is provided on the second layer-forming porous film side included in the laminate before the hot-pressure lamination, and the pressing surface thereof is the exposed surface of the second layer-forming porous film. Pressure contacted. The compression elastic modulus of the second pressure contact member and the arithmetic average roughness of the pressing surface have a relationship defined by the following equations (3) and (4) with respect to the porous film for forming the second layer. It is preferable to set so as to satisfy.
Regarding formula (3), the difference between Ra _(RS2) and Ra _(PM2) is not particularly limited, but is preferably 0.1 μm or more. Regarding formula (4), the difference between E _(RS2) and E _(PM2) is not particularly limited, but is preferably 100 MPa or more.
(I) Ra _(RS2) <Ra _(PM2) (Formula 3)
Ra _(RS2) : Arithmetic mean roughness of the pressing surface of the second pressure contact member Ra _(PM2) : Surface of the porous film for forming the second layer on which the pressing surface of the second pressure contact member is pressed (exposed surface) ) Arithmetic average roughness (ii) E _(RS2) > E _(PM2) (Formula 4)
E _(RS2) : Compression elastic modulus of the second pressure contact member E _(PM2) : Compression elastic modulus of the porous film for forming the second layer Note that the second pressure forming member of the second pressure contact member has The arithmetic average roughness (Ra) of the pressing surface to the porous membrane is preferably smaller than 1.5 μm.

Claims

A method for producing a porous film having a first layer made of a porous film containing a fluororesin and a second layer made of a porous film,
Laminating the porous film for forming the first layer and the porous film for forming the second layer to form a laminate;
A step of pressing the pressing surface of the pressure contact member to the surface on the porous film side for forming the first layer of the laminated body under heating, and thermocompression bonding the laminated surface of each porous film of the laminated body;
Have
The arithmetic average roughness (Ra) of the pressing surface of the pressing member is smaller than the arithmetic average roughness (Ra) of the surface of the porous film for forming the first layer to which the pressing surface is pressed, and
The method for producing a porous film, wherein the compression elastic modulus of the pressure contact member is larger than the compression elastic modulus of the porous film for forming the first layer.

The pressure contact member arranged on the porous layer side for forming the first layer of the laminate is a first pressure contact member, facing the pressing surface of the first pressure contact member, and the second of the laminate The pressing surface of the second pressure contact member is disposed on the porous membrane side for layer formation, a nip portion is formed by these pressing surfaces, and the thermocompression bonding is performed at the nip portion,
Arithmetic surface roughness of the pressing surface (Ra) is a porous surface arithmetic average roughness of the film for the second layer forming the pressing surface of the second pressing member is pressed against the second pressing member ( Ra) and the compressive elastic modulus of the second pressure contact member is larger than the compressive elastic modulus of the porous film for forming the second layer,
The method for producing a porous membrane according to claim 1.

The method for producing a porous membrane according to claim 1, wherein the first layer is a polytetrafluoroethylene (PTFE) stretched porous membrane.

The method for producing a porous membrane according to any one of claims 1 to 3, wherein the second layer functions as a support for the first layer.

The method for producing a porous film according to any one of claims 1 to 4, wherein the porous film for forming the second layer is made of a nonwoven fabric.

The method for producing a porous membrane according to claim 5, wherein the nonwoven fabric is a nonwoven fabric in which fibers are joined by a needle punch method.

The method for producing a porous membrane according to any one of claims 1 to 6, wherein an arithmetic average roughness (Ra) of the surface of the porous membrane for forming the first layer is 1.5 µm or less.

The method for producing a porous membrane according to any one of claims 1 to 7, wherein a compression elastic modulus of the porous membrane for forming the first layer is 2 MPa or more.

The method for producing a porous membrane according to any one of claims 2 to 8, wherein a compression elastic modulus of the porous membrane for forming the second layer is 2 MPa or more.