JP5329350B2 - Polytetrafluoroethylene black porous membrane, and ventilation membrane, ventilation member and waterproof sound-permeable membrane using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black PTFE porous film (PTFE black porous film) whose color fading by heat and/or light is suppressed more than that of a conventional colored PTFE porous film and which has excellent color fading resistance in the polytetrafluoroethylene (PTFE) porous film which is colored in black. <P>SOLUTION: The PTFE black porous film colored in black has achromatic luminance of a principal surface measured according to JIS Z8721 of N2 or below. The PTFE black porous film is suitable for an aeration film permeating gas while shielding water and/or dust, for example, a waterproof sound-propagating film, a waterproof aeration film and a dust-proof aeration film. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a black polytetrafluoroethylene porous membrane (polytetrafluoroethylene black porous membrane) in which fading due to heat and / or light is suppressed as compared with the conventional one. The present invention also relates to a gas permeable membrane and a gas permeable member using the porous membrane.

  In recent years, electronic devices such as mobile phones, notebook computers, electronic notebooks, digital cameras, and game machines are generally equipped with voice functions. Although these devices are desired to have a waterproof structure, the housing of an electronic device equipped with an audio function is usually provided with openings at positions corresponding to the sound generation unit and the sound reception unit such as a speaker, a microphone, and a buzzer. Since it is necessary to transmit sound through this opening, it is difficult to make a waterproof structure while ensuring sound function. Until now, by closing the opening provided in the housing with a waterproof sound-permeable membrane, both sound permeability and waterproofness in the opening have been achieved. The waterproof sound-permeable membrane is a thin film made of a material that does not easily block sound transmission, and the arrangement of the membrane in the opening can suppress water from entering the housing while obtaining good sound permeability. For the waterproof sound-permeable membrane, a gas permeable membrane that allows gas to permeate while blocking water is preferable, and more specifically, a gas permeable membrane having a polytetrafluoroethylene (PTFE) porous film is preferable (Japanese Patent Application Laid-Open No. 2004-124). -83811).

  By the way, the original color of the PTFE porous membrane is white. The waterproof sound-permeable membrane is usually disposed inside the housing so as to close the opening, but the white membrane is easily noticeable. When the film is conspicuous, it becomes an obstacle to the design of the electronic device and stimulates the curiosity of the user, so that the film is likely to be damaged by the piercing of a writing instrument or the like. For this reason, there is a need for a black PTFE porous membrane (PTFE black porous membrane) that is inconspicuous when placed in a housing.

  A PTFE black porous membrane is disclosed in JP-A-8-27304. Further, a PTFE porous membrane which is not black but is colored gray or pink is described in JP-A-7-289865.

  In addition to the waterproof sound-permeable membrane, the gas-permeable membrane having a PTFE porous membrane can be used as a waterproof gas-permeable membrane or a dust-proof gas-permeable membrane that allows gas to pass through while blocking water and / or dust.

JP 2004-83811 A JP-A-8-27304 Japanese Unexamined Patent Publication No. 7-289865

  In conventional colored PTFE porous membranes, color fading is likely to occur due to exposure to a high temperature atmosphere or light irradiation (typically sunlight irradiation). An object of the present invention is to provide a PTFE black porous membrane excellent in fading resistance in which fading due to heat and / or light is suppressed as compared with a conventional colored PTFE porous membrane.

PTFE black porous membrane of the present invention is dyed in black, achromatic lightness of the main surface were measured according to JIS Z8721 is Ri der N2 or less, the surface density of Ru 1 to 10 g / m ² der.

  The gas permeable membrane of the present invention is a gas permeable membrane that allows gas to permeate while blocking water and / or dust, and has the PTFE black porous membrane of the present invention.

The ventilation member of the present invention includes the gas permeable membrane of the present invention and a support member that supports the gas permeable membrane.
The waterproof sound-permeable membrane of the present invention is a waterproof sound-permeable membrane in which sound permeability in the opening is ensured while suppressing the intrusion of water into the housing by being disposed in the opening of the housing. It consists of a breathable membrane.

  Fading resistance in which fading due to heat and / or light is suppressed as compared with conventional colored PTFE porous membranes by using a stained PTFE porous membrane having a lightness (achromatic lightness) of a main surface of a predetermined value or less. It becomes a PTFE black porous membrane excellent in.

It is sectional drawing which shows an example of the air permeable membrane of this invention typically. It is sectional drawing which shows typically another example of the air permeable membrane of this invention. It is sectional drawing which shows typically another example of the air permeable membrane of this invention. It is sectional drawing which shows typically another example of the air permeable membrane of this invention. It is a perspective view which shows typically an example of the ventilation member of this invention. It is a figure for demonstrating the presumed reason that the ventilation film of this invention is excellent in fade resistance.

(PTFE black porous membrane)
The PTFE black porous film of the present invention is a dyed PTFE porous film dyed black, and the lightness of the main surface is N2 or less in terms of achromatic lightness measured according to JIS Z8721. This lightness is based on the Munsell color system, and N0 is an ideal black color, N10 is an ideal white color, and is a numerical value divided so that the difference in lightness perception is approximately equal. Indicated. The lightness of N2 or less means that the color is black indicated by N2 or darker than that. Hereinafter, the achromatic lightness measured according to JIS Z8721 is simply referred to as “lightness”.

  Such a PTFE black porous membrane is prepared by, for example, immersing the PTFE porous membrane in a dye-containing dyeing solution or applying a dye-containing dyeing solution to the PTFE porous film, and then the dye contained in the dyeing solution. The solvent can be removed by drying or the like. The method of immersion and application is not particularly limited. The dye is a dye capable of dyeing a white PTFE porous membrane not colored at all to N2 or less in terms of the lightness of the main surface, and azo dyes, oil-soluble dyes and the like can be used. The dyeing solution usually contains a dye and a solvent that dilutes the dye and improves the workability of dyeing. Since the PTFE porous membrane is chemically stable, the type of solvent is not particularly limited, and can be appropriately selected according to the type of dye and the workability of dyeing. The concentration of the dye in the dyeing solution needs to be a concentration that allows a white PTFE porous membrane not colored at all to be dyed to N2 or less in terms of the brightness of the main surface, and is usually 5% by weight or more.

  A PTFE porous membrane dyed black is obtained by a known method. For example, a kneaded product of PTFE fine powder and a molding aid is formed into a sheet by extrusion molding and rolling, from which the molding aid is removed to form a molded body sheet, and then the resulting sheet is further stretched to form it can. The PTFE black porous membrane of the present invention obtained from the PTFE porous membrane thus produced has a porous structure having pores between voids of infinitely formed PTFE fine fibers (fibrils). The average pore diameter and porosity in this porous structure can be adjusted by changing the stretching conditions of the sheet, and the specific values may be selected according to the use of the PTFE black porous membrane of the present invention.

  The PTFE black porous film of the present invention may be subjected to a liquid repellent treatment. In this case, the porous film is excellent in water repellency and oil repellency. Such a porous membrane is suitable for use as a gas permeable membrane including a waterproof sound-permeable membrane. The liquid repellent treatment can be performed by a known method after the PTFE porous membrane is dyed black. The liquid repellent used for the liquid repellent treatment is not particularly limited, and is typically a material containing a polymer having a perfluoroalkyl group.

(Ventilation membrane)
The configuration of the gas permeable membrane of the present invention is not particularly limited as long as it has the PTFE black porous membrane of the present invention.

  FIG. 1 is an example of a gas permeable membrane of the present invention. The gas permeable membrane 1 in FIG. 1 is composed of the PTFE black porous membrane 11 of the present invention. The gas permeable membrane 1 has a characteristic of allowing gas to pass through while blocking water and / or dust based on the porous structure of the PTFE black porous membrane 11. The gas permeable membrane 1 is black, and is not conspicuous as compared with the white PTFE porous membrane, for example, when it is disposed in the opening of the housing of the electronic device. Further, since the gas permeable membrane 1 has a single-layer structure of the PTFE black porous membrane 11, the surface density can be kept low. The lower the surface density of the gas permeable membrane, the smaller the sound transmission loss in the membrane, thereby improving the sound permeability. For this reason, the air permeable membrane 1 is disposed in an opening of a housing in an electronic device having a sounding part and / or a sound receiving part, and is used as a waterproof sound permeable film for ensuring sound permeability and waterproofness in the opening. Is particularly suitable.

  Of course, the gas permeable membrane 1 is also suitable for uses other than the waterproof sound permeable membrane, for example, as a waterproof gas permeable membrane or a dust proof gas permeable membrane that utilizes gas permeation while blocking water and / or dust. The waterproof breathable membrane (dust-proof breathable membrane) is disposed in the housing of vehicle electrical components such as lamps, motors, sensors, and ECUs, for example, to ensure ventilation inside and outside the housing and to change the pressure inside the housing due to temperature changes Used to relax.

  The average pore diameter of the PTFE black porous membrane 11 in the gas permeable membrane 1 is generally 0.01 to 20 μm, preferably 0.05 to 5 μm. When the gas permeable membrane 1 is used as a waterproof sound-permeable membrane, the average pore diameter of the PTFE black porous membrane 11 is preferably 1 μm or less, more preferably 0.7 μm or less, from the viewpoint of achieving both waterproofness and sound permeability. More preferably, it is 0.5 μm or less. Although the minimum of an average hole diameter is not specifically limited, For example, it is 0.1 micrometer. The average pore diameter of the PTFE porous membrane can be measured in accordance with the provisions of ASTM F316-86. For example, a commercially available measuring device capable of automatic measurement in accordance with the provisions (such as Perm-Porometer available from Porous Material Inc., USA) ) Can be used to measure the average pore size of the PTFE porous membrane.

When the gas permeable membrane 1 is used as a waterproof sound permeable membrane, the surface density of the gas permeable membrane 1 is preferably 1 to 10 g / m ² from the viewpoint of achieving both physical strength and sound permeability as a membrane. more preferably 10 g / m ^2, more preferably 2~7g / m ^2. When the air-permeable membrane is used as a waterproof air-permeable membrane or a dust-proof air-permeable membrane that does not require good sound permeability, the surface density of the air-permeable membrane 1 is not particularly limited.

  The PTFE black porous film 11 may be subjected to a liquid repellent treatment. In this case, the water repellency and oil repellency of the gas permeable film 1 are improved. The effect of using the PTFE black porous film 11 subjected to the liquid repellent treatment is the same for the air-permeable films 2, 3, and 4 shown in FIGS.

  FIG. 2 is another example of the gas permeable membrane of the present invention. The gas permeable membrane 2 in FIG. 2 has a laminated structure of the PTFE black porous membrane 11 of the present invention and a gas permeable support material 12 that supports the porous membrane 11. The gas permeable membrane 2 has a characteristic of allowing gas to pass through while blocking water and / or dust based on the porous structure of the PTFE black porous membrane 11. In the gas permeable membrane 2, the black porous membrane 11 is exposed. For example, when the gas permeable membrane 2 is disposed in the opening of the casing of the electronic device, the PTFE black porous membrane 11 faces the outside of the casing. If so, it is less noticeable than the white PTFE porous membrane. The use of the gas permeable membrane 2 is not particularly limited, and can be suitably used for a waterproof sound permeable membrane, a waterproof gas permeable membrane, a dustproof gas permeable membrane, and the like.

  Although the material and structure of the air-permeable support material 12 are not particularly limited, it is preferable that the air-permeable support material 12 has better air permeability than the PTFE black porous membrane 11. The breathable support material 12 is, for example, a woven fabric, a nonwoven fabric, a mesh, a net, a sponge, a foam, or a porous body made of metal or resin or a composite material thereof. The resin is, for example, polyolefin, polyester, polyamide, polyimide, aramid, fluororesin, or ultrahigh molecular weight polyethylene. When laminating the PTFE black porous membrane 11 and the air-permeable support material 12, they may be joined using various joining methods such as thermal lamination, heat welding, and ultrasonic welding.

  The gas permeable membrane 2 may have two or more layers of the PTFE black porous membrane 11 and / or two or more layers of the permeable support material 12, and in this case, the stacking order is not particularly limited. However, in order to make it less noticeable than the white PTFE porous membrane when arranged in the opening of the casing of the electronic device, as shown in FIG. 2, the PTFE black porous membrane is formed on at least one main surface. 11 is preferably exposed. In other words, the gas permeable membrane of the present invention may have a laminated structure of the PTFE black porous membrane of the present invention and a gas permeable support material. In that case, the PTFE black porous membrane is at least on one main surface. It is preferable that it is exposed.

  The average pore diameter of the PTFE black porous membrane 11 in the gas permeable membrane 2 is as illustrated in the description of the gas permeable membrane 1 shown in FIG. The average pore diameter of the PTFE black porous membrane 11 when the gas permeable membrane 2 is used as a waterproof sound permeable membrane is also as exemplified in the description of the gas permeable membrane 1 shown in FIG. When the gas permeable membrane 2 has two or more layers of the PTFE black porous membrane 11, it is sufficient that at least one layer of the PTFE black porous membrane 11 has the average pore diameter exemplified.

When the gas permeable membrane 2 is used as a waterproof sound permeable membrane, the surface density of the gas permeable membrane 2 is (PTFE black porous membrane 11 and air permeable support) from the viewpoint of achieving both physical strength and sound permeable properties as the membrane. 1 to 10 g / m ² is preferable, and ² to 10 g / m ² is more preferable, and ² to 7 g / m ² is more preferable.

  FIG. 3 is another example of the gas permeable membrane of the present invention. 3 has a laminated structure of the PTFE black porous membrane 11 of the present invention and another PTFE porous membrane 13 different from this. The PTFE porous membrane 13 may be uncolored (that is, white) or may be colored in an arbitrary color (for example, black), or may be stained in black so that the lightness of the main surface is N2 or less. The brightness of the main surface may be N3 or higher (that is, even the PTFE black porous membrane of the present invention). Similar to the PTFE black porous membrane 11, the PTFE porous membrane 13 has a porous structure in which voids between innumerably formed PTFE fine fibers (fibrils) are pores. The gas permeable membrane 3 is based on the porous structure of at least one PTFE porous membrane selected from the PTFE black porous membrane 11 and the PTFE porous membrane 13 and has a characteristic of allowing gas to pass through while blocking water and / or dust. Have

  In the gas permeable membrane 3, the black porous membrane 11 is exposed. For example, when the gas permeable membrane 3 is disposed in the opening of the casing of the electronic device, the PTFE black porous membrane 11 faces the outside of the casing. If so, it is less noticeable than the white PTFE porous membrane. That is, the gas permeable membrane of the present invention may have a laminated structure of the PTFE black porous membrane 11 of the present invention and another PTFE porous membrane 13 different from this, and in that case, at least one of the main membranes It is preferable that the PTFE black porous membrane is exposed on the surface.

  The gas permeable membrane 3 may have two or more layers of the PTFE black porous membrane 11 and / or two or more layers of the PTFE porous membrane 13, and in this case, the stacking order is not particularly limited.

  The use of the gas permeable membrane 3 is not particularly limited, and can be suitably used for a waterproof sound permeable membrane, a waterproof gas permeable membrane, and a dust proof gas permeable membrane.

  In the gas permeable membrane 3, the average pore diameter of at least one PTFE porous membrane selected from the PTFE black porous membrane 11 and the PTFE porous membrane 13 is as illustrated in the description of the gas permeable membrane 1 shown in FIG. Similarly, when the gas permeable membrane 3 is used as a waterproof sound permeable membrane, the average pore diameter of at least one PTFE porous membrane selected from the PTFE black porous membrane 11 and the PTFE porous membrane 13 is the gas permeable membrane shown in FIG. This is as exemplified in the description of 1. When the gas permeable membrane 3 has two or more layers of the PTFE black porous membrane 11 and / or the PTFE porous membrane 13, at least one layer of the PTFE black porous membrane 11 or the PTFE porous membrane 13 has the average pore diameter exemplified. That's fine. The average pore diameter of the PTFE black porous membrane 11 and the average pore diameter of the PTFE porous membrane 13 may be the same or different.

When the gas permeable membrane 3 is used as a waterproof sound permeable membrane, the surface density of the gas permeable membrane 3 is (PTFE black porous membrane 11 and PTFE porous) from the viewpoint of achieving both physical strength and sound permeability as a membrane. total) 1 to 10 g / m ² is preferably a plurality of layers comprising a membrane 13, more preferably 2 to 10 g / m ^2, more preferably 2~7g / m ^2.

  FIG. 4 is another example of the gas permeable membrane of the present invention. The gas permeable membrane 4 in FIG. 4 further includes a gas permeable support material 12 in addition to the gas permeable membrane 3 shown in FIG. In the gas permeable membrane 4, the black porous membrane 11 is exposed. The breathable support member 12 is as described in the description of the breathable membrane 2 shown in FIG.

  The gas permeable membrane of the present invention may have any member other than the PTFE black porous membrane 11, the gas permeable support material 12, and the PTFE porous membrane 13. At this time, it is preferable that the PTFE black porous membrane 11 is exposed on at least one main surface of the gas permeable membrane of the present invention.

(Ventilation member)
An example of the ventilation member of the present invention is shown in FIG. The ventilation member 5 shown in FIG. 5 includes the gas permeable membrane 1 of the present invention. The gas permeable membrane 1 has a disk shape, and a ring-shaped support member 14 is attached to the peripheral portion of the gas permeable membrane 1. According to the embodiment in which the ring-shaped support member 14 is provided, the gas permeable membrane 1 can be reinforced and the handling thereof is facilitated. Moreover, since the support member 14 becomes an allowance to attach to the housing | casing of an electrical product, the attachment workability | operativity to the housing | casing of the ventilation film 1 improves.

  The shape of the support member is not particularly limited as long as it can support the gas permeable membrane of the present invention.

  The material of the support member is not particularly limited, and is typically made of resin, metal, or a composite material thereof.

  The bonding method between the gas permeable membrane 1 and the support member 14 is not particularly limited, and for example, methods such as heat welding, ultrasonic welding, bonding with an adhesive, and bonding with a double-sided tape can be applied.

  Initially, the evaluation method of the PTFE black porous membrane produced by the present Example and the non-colored PTFE porous membrane is shown.

[brightness]
The brightness of the PTFE porous membrane was evaluated using a standard color table (glossy plate) according to JIS Z8721.

[Air permeability]
The air permeability of the PTFE porous membrane was evaluated according to JIS P8117 (Gurley method).

[Water pressure resistance]
The water pressure resistance of the PTFE porous membrane was determined using a water resistance tester (high water pressure method) described in JIS L1092. However, since the membrane deformed remarkably in the area specified in JIS L1092, a stainless mesh (opening diameter: 2 mm) was placed on the opposite side of the pressure surface of the membrane, and the measurement was performed with the deformation suppressed.

[Liquid repellency]
The copy paper and the PTFE porous membrane were laminated so that the copy paper was on the bottom, and a drop of kerosene was dropped on the PTFE porous membrane using a dropper, and then left for 1 minute. Thereafter, the porous film was removed to confirm the state of the copy paper. When the copy paper was wet with kerosene, the PTFE porous film was not liquid-repellent, and when it was not wet, the liquid-repellent was determined.

(Example)
After mixing 100 parts by weight of PTFE fine powder (Daikin Industries, F104) and 20 parts by weight of n-dodecane (Japan Energy) as a molding aid, the resulting mixture is compressed using a cylinder and then ram. Extruded into a sheet-like mixture. Next, the obtained sheet-like mixture was rolled to a thickness of 0.2 mm through a pair of metal rolls, and the molding aid was dried and removed by heating at 150 ° C. to obtain a PTFE sheet molded body. Next, the obtained sheet molded body was stretched in the longitudinal direction (rolling direction) at a stretching temperature of 260 ° C. and a stretching ratio of 5 times, and then stretched in the width direction at a stretching temperature of 150 ° C. and a stretching ratio of 20 times. The whole was fired at 380 ° C., which is a temperature exceeding the melting point of PTFE, to obtain a porous PTFE membrane. The obtained PTFE porous membrane had an average pore size of 0.2 μm and an areal density of 4 g / m ² . This value was hardly changed by subsequent dyeing treatment and liquid repellent treatment.

  Next, 5 parts by weight of a black dye (manufactured by Orient Chemical Industries, VALIFAST BLACK 3810) and 95 parts by weight of methyl ethyl ketone (produced by Taihei Kasei) as a solvent for the dye are mixed with the PTFE porous membrane produced as described above. After immersing in the dyeing solution obtained for several seconds, the whole was heated to 100 ° C. to remove the solvent by drying to obtain a porous PTFE membrane dyed black.

  Next, 20 parts by weight of the liquid repellent (X-70-029C, manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts by weight of the solvent of the liquid repellent (manufactured by Shin-Etsu Chemical Co., Ltd., FS thinner) were prepared as described above. After being immersed in a liquid repellent treatment agent obtained for a few seconds, the whole was heated to 100 ° C. and the solvent was removed by drying to obtain a liquid repellent PTFE black porous membrane.

  The resulting PTFE black porous membrane had a lightness of N2, an air permeability of 16 seconds / 100 mL, a water pressure resistance of 210 kPa, and a liquid repellency of “Yes”.

(Comparative Examples 1-3)
A liquid repellent PTFE black porous membrane (Comparative Examples 1 and 2) and a liquid repellent were treated in the same manner as in the Examples except that the concentration of the black dye in the dye liquid was lowered or the dyeing itself with the black dye was not performed. A treated uncolored PTFE porous membrane (Comparative Example 3) was obtained. The evaluation results of the PTFE porous membranes produced in Comparative Examples 1 to 3 are shown in Table 1 below together with the evaluation results of the PTFE porous membranes produced in Examples.

  The properties of the PTFE porous membranes produced in Examples and Comparative Examples 1 to 3 were almost the same as those other than brightness. The lightness N2 felt black, the lightness N3 and N4 felt gray, and the lightness N9 felt white.

  Next, each PTFE black porous membrane produced in Examples and Comparative Examples 1 and 2 was exposed to sunny sunlight for 3 days. Exposure to solar radiation was carried out with each porous membrane kept horizontal in the field and allowed to stand. The brightness of the main surface of each PTFE black porous membrane 1 day and 3 days after the start of exposure is shown in Table 2 below.

  As shown in Table 2, the PTFE black porous membranes produced in Comparative Examples 1 and 2 faded by exposure to sunlight, but the PTFE black porous membrane produced in Examples did not fade.

  Next, the high temperature exposure test was done with respect to each PTFE black porous membrane produced by the Example and Comparative Examples 1-2. The high temperature exposure test was carried out by accommodating the porous membrane in a constant temperature room maintained at a predetermined temperature shown in Tables 3 to 5 below for a maximum of 70 days. Table 3 shows the lightness evaluation results for the PTFE black porous membrane prepared in the examples, Table 4 shows the lightness evaluation results for the PTFE black porous membrane prepared in Comparative Example 1, and the PTFE black porous material prepared in Comparative Example 2 Table 5 shows the evaluation results of the lightness with respect to the membrane.

  As shown in Tables 3 to 5, although the PTFE black porous membranes prepared in Comparative Examples 1 and 2 faded by exposure to a high temperature of 90 ° C. or higher, the PTFE black porous membranes prepared in the examples were 120. It was not discolored by exposure to ℃.

  In the example in which the lightness is N2, the present inventors presume the following reason why the fading due to light or heat did not proceed. First, the absolute amount of the dye adhering to the PTFE porous membrane is different between the case where the lightness is N2 and the case where the lightness is N3 or more. As the amount of adhesion increases, even if the dye near the surface of the porous film is faded by light or heat, the absolute amount of the dye that remains without fading increases. The increase in the absolute amount of the remaining dye acts in the direction of preventing fading. Second, the amount of dye attached to the PTFE porous membrane may not be linearly proportional to the brightness based on human vision. Specifically, as shown in FIG. 6, it is considered that there is a region where the lightness (blackness in FIG. 6) changes greatly with respect to the change in the amount of dye. When the lightness is N3 or more, light or heat is applied. Thus, it is considered that the amount of the dye adhering to the porous film can reach this change region relatively easily. In other words, the lightness of N2 is considered to be a threshold that does not easily reach the region where the amount of dye changes greatly.

  The PTFE black porous membrane of the present invention can be used for the same applications as conventional PTFE porous membranes, for example, waterproof sound-permeable membranes, waterproof breathable membranes, and dust-proof breathable membranes.

1, 2, 3, 4 Breathing membrane 5 Breathing member 11 PTFE black porous membrane 12 Breathable support material 13 PTFE porous membrane 14 Support member

Claims (6)

Stained black,
Achromatic color brightness of the main surface was measured in accordance with JIS Z8721 is Ri der N2 below,
Areal density Ru 1 to 10 g / m ² der polytetrafluoroethylene black porous membrane. An air-permeable membrane that allows gas to pass through while blocking water and / or dust,
A gas permeable membrane having the polytetrafluoroethylene black porous membrane according to claim 1. Having a laminated structure of the polytetrafluoroethylene black porous membrane and a breathable support material;
The gas permeable membrane according to claim 2, wherein the polytetrafluoroethylene black porous membrane is exposed on at least one main surface. A laminated structure of the polytetrafluoroethylene black porous membrane and a polytetrafluoroethylene porous membrane having an achromatic color brightness of N3 or more measured according to JIS Z8721;
The gas permeable membrane according to claim 2, wherein the polytetrafluoroethylene black porous membrane is exposed on at least one main surface. The gas permeable membrane according to any one of claims 2 to 4,
A ventilation member comprising a support member for supporting the ventilation membrane. A waterproof sound-permeable membrane in which sound permeability in the opening is secured while suppressing the intrusion of water into the inside of the housing by the arrangement in the opening of the housing,
The waterproof sound-permeable membrane comprised from the air permeable membrane in any one of Claims 2-4.

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