JP6396736B2 - Waterproof ventilation membrane, waterproof ventilation member and waterproof ventilation structure including the same - Google Patents

Description

  The present invention relates to a waterproof breathable membrane having both waterproof properties and breathability, and a waterproof breathable member and a waterproof vent structure including the waterproof breathable membrane.

  A housing that houses an electronic circuit board such as a vehicle ECU (Electrical Control Unit) and a solar battery control board; a housing that houses electronic equipment or components such as motors, light sources and sensors; electric toothbrushes and shavers An opening for ensuring air permeability between the outside and the inside of the casing is often provided in a casing of such a home appliance; and a casing of an information terminal such as a mobile phone. Thereby, for example, the pressure difference generated between the inside and the outside of the housing can be eliminated or reduced. In the opening, especially when an article contained in the case dislikes water, gas (usually air) is transmitted between the inside and outside of the case to ensure air permeability and the outside of the case. In many cases, a waterproof breathable membrane having both breathability and waterproofness is disposed to prevent water from entering the inside through the opening.

  An example of the waterproof breathable membrane is a stretched porous membrane having a dispersed structure of innumerable pores generated by stretching. Patent Document 1 discloses a waterproof gas permeable membrane made of a stretched porous membrane of polytetrafluoroethylene (PTFE). Another example of the waterproof breathable membrane is a non-porous polymer film in which a plurality of through holes penetrating in the thickness direction are formed (see Patent Document 2). The waterproof breathable membrane of Patent Document 2 can be formed by chemical etching after irradiating a non-porous polymer film with an ion beam.

JP 2003-318557 A JP 2012-20279 A

  In recent years, there has been a demand for a waterproof breathable membrane having a high degree of freedom in controlling breathability and waterproofness. For example, it is possible to provide a waterproof breathable membrane that achieves a high level of compatibility between air permeability and waterproof properties at a high level. The required air permeability can be ensured while reducing the area, that is, the size of the waterproof ventilation structure can be reduced. Thereby, the freedom degree of design of an electronic device, especially a portable information terminal improves, for example.

  The waterproof breathable membrane of Patent Document 1 has a membrane structure composed of innumerable fine PTFE fibrils generated by stretching and innumerable pores generated between the fibrils by stretching. Are distributed in a three-dimensional manner and are continuous with each other. For this reason, the waterproof breathable membrane of Patent Document 1 has a large variation in the size and shape of the pores in the membrane, increasing the degree of freedom of control of breathability and waterproofness, for example, high breathability and waterproofness. Difficult to balance at level.

  On the other hand, the waterproof breathable membrane of Patent Document 2 has high uniformity in the size and shape of the through holes, and the size (diameter) of the through holes can be changed depending on the conditions of chemical etching. Compared to the membrane, the degree of freedom in controlling breathability and waterproofness is high. However, it is still inadequate for the recent demand for the degree of freedom.

  One of the objects of the present invention is to provide a waterproof breathable membrane having a higher degree of freedom in controlling breathability and waterproofness than before, and to provide a waterproof vent member and a waterproof vent structure provided with the waterproof breathable membrane. .

  The waterproof breathable membrane of the present invention is composed of a polymer film having a through hole extending from one main surface to the other main surface, and the through hole is a straight hole in which the central axis of the through hole extends linearly. And the through hole has a shape in which an area of a cross section perpendicular to a direction in which the central axis extends increases from one main surface to the other main surface of the polymer film, The ratio a / b between the opening diameter a of the through hole and the opening diameter b of the through hole in the other main surface is 80% or less.

  The waterproof breathable member of the present invention comprises the above waterproof breathable membrane of the present invention and a support joined to the waterproof breathable membrane.

  The waterproof ventilation structure of the present invention is disposed so as to close the housing having an opening and the opening, and allows water to pass through the opening from the outside while allowing gas to pass between the inside and the outside of the housing. A waterproof breathable membrane that prevents the intrusion of water, and the waterproof breathable membrane is the waterproof breathable membrane of the present invention.

  According to the present invention, it is possible to obtain a waterproof gas permeable membrane having a higher degree of freedom in air permeability and waterproof control than conventional waterproof gas permeable membranes.

It is sectional drawing which shows typically an example of the waterproof breathable film of this invention. It is sectional drawing which shows typically another example of the waterproof breathable film of this invention. It is sectional drawing which shows typically another example of the waterproof breathable film of this invention. In the waterproof breathable membrane of the present invention, it is a top view showing typically an example of the relation between the through-holes in the direction in which the through-holes extend. In the waterproof breathable membrane of the present invention, it is a top view showing typically another example of the relation between the through holes in the direction in which the through holes extend. It is sectional drawing which shows typically another example of the waterproof breathable film of this invention. It is sectional drawing which shows typically an example different from the above of the waterproof breathable film of this invention. It is a method for forming a polymer film constituting the waterproof gas-permeable membrane of the present invention, and is a schematic diagram for explaining an outline of ion beam irradiation in a method using ion beam irradiation and subsequent chemical etching. It is a schematic diagram for demonstrating an example of ion beam irradiation in the method of forming the polymer film which comprises the waterproof breathable film of this invention, Comprising: The method using ion beam irradiation and subsequent chemical etching. (A)-(c) is a method of forming the polymer film which comprises the waterproof breathable film of this invention, Comprising: An example of progress of chemical etching in the method using ion beam irradiation and subsequent chemical etching is a model FIG. It is a perspective view which shows typically an example of the waterproof ventilation member of this invention. It is a top view which shows typically another example of the waterproof ventilation member of this invention. It is sectional drawing which shows typically an example of the waterproof ventilation structure of this invention. It is a figure which shows the observation image by the scanning electron microscope (SEM) of one main surface (masking surface) of the polymer film produced in Example 1. FIG. It is a figure which shows the observation image by SEM of the other main surface (etching surface) of the polymer film produced in Example 1. FIG.

[Waterproof breathable membrane]
FIG. 1 shows an example of the waterproof breathable membrane of the present invention. A waterproof breathable membrane 1 shown in FIG. 1 includes a polymer film 2 and a liquid repellent layer 3 formed on the main surface of the polymer film 2. The polymer film 2 has a through-hole 5 extending from one main surface 4a of the film 2 to the other main surface 4b. The through-hole 5 is a straight hole in which the central axis (axis) 6 of the through-hole 5 extends linearly, and the area of the cross section 7 perpendicular to the direction in which the central axis 6 extends has one main surface of the polymer film 2. It has a shape that increases from 4a toward the other main surface 4b. The ratio a / b between the diameter (opening diameter) a of the opening 8a of the through hole 5 in one main surface 4a and the diameter b of the opening 8b of the through hole 5 in the other main surface 4b is 80% or less. The liquid repellent layer 3 is also formed on the surface of the through hole 5 (the surface of the film 2 in the through hole 5). The liquid repellent layer 3 formed on the main surface of the polymer film 2 has openings at positions corresponding to the through holes 5 of the film 2 (positions corresponding to the openings 8a and 8b). The polymer film 2 is, for example, a non-porous film that does not have a path other than the through-hole 5 that can be vented in the thickness direction, and is typically non-porous except for the through-hole 5. (Solid) film. In FIG. 1, the diameter of the through hole 5 is exaggerated for easy understanding. The same applies to the subsequent drawings.

  The waterproof gas-permeable membrane 1 shown in FIG. 1 differs from the waterproof gas-permeable membrane disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2012-20279) at least in the shape of the through holes. More specifically, the through hole of the waterproof breathable membrane of Patent Document 2 is a “straight hole that penetrates the resin film linearly with a constant cross-sectional shape” (paragraph 0015), whereas the waterproof hole of FIG. The through-hole 5 of the gas permeable membrane 1 is also a straight hole having a central axis extending linearly, but the area of the cross section 7 perpendicular to the direction in which the central axis 6 extends has an area from one main surface 4a of the film 2 to the other main surface. It has a shape that increases toward the surface 4b. In the waterproof breathable membrane 1, the opening diameter a of the through hole 5 on one main surface 4a of the film 2 is not equal to the opening diameter b of the through hole 5 on the other main surface 4b based on the shape of the through hole 5. The opening diameter a is 80% or less with respect to the opening diameter b.

  Based on at least the shape of the through-hole 5, the waterproof gas-permeable membrane 1 has a higher degree of freedom of air permeability and waterproof control than the conventional waterproof gas-permeable membrane. For example, in contrast to the stretched porous membrane of Patent Document 1 in which pores that are three-dimensionally distributed throughout the membrane and are continuous with each other are used as ventilation paths, the polymer film 2 constituting the waterproof ventilation membrane 1 is: It is a non-porous film that does not have a ventilation path in the thickness direction other than through holes that are straight holes, and the uniformity of the size and shape of the through holes that become the ventilation paths is higher. The shape, opening diameter, and ratio a / b of the through hole 5 can be changed depending on the manufacturing conditions in the method. For this reason, compared to the stretched porous membrane of Patent Document 1, the breathability and waterproofness control of the waterproof breathable membrane 1 are high, and for example, the breathability and waterproofness can be compatible at a high level.

  On the other hand, compared with the waterproof breathable membrane of Patent Document 2 having a through-hole penetrating the resin film with a constant cross-sectional shape, the waterproof breathable membrane 1 has a change in the shape of the cross-section 7 of the through-hole 5 and the polymer film 2. The difference in the diameters of the openings 8a and 8b in the main surfaces 4a and 4b improves the degree of freedom in controlling the breathability and waterproofness of the waterproof breathable membrane 1, for example, achieving both high breathability and waterproofness at a high level. be able to. As a more specific and typical example, the main surface having an opening 8b having a relatively large opening diameter is more waterproof to prevent water from entering from the main surface 4a having the opening 8a having a relatively small opening diameter. It is larger than the waterproof property that prevents water from entering from 4b. That is, the waterproof gas-permeable membrane 1 is a membrane having anisotropy between main surfaces (between front and back) with respect to its waterproof property. Further, the waterproof breathable membrane 1 with the same opening diameter has higher air permeability than the waterproof breathable membrane having a through-hole penetrating the resin film with a constant cross-sectional shape. Such high anisotropy and air permeability contribute to a high degree of freedom in controlling air permeability and waterproofness as a waterproof air-permeable membrane. Further, the ability to change the shape, opening diameter, and ratio a / b of the through hole 5 according to the manufacturing conditions in the manufacturing method described later also works in the direction of increasing the degree of freedom.

  As shown in FIG. 1, the through hole 5 has an asymmetric shape in the film thickness direction of the waterproof breathable membrane 1, in which the shape of the cross section 7 changes in the direction in which the central axis 6 extends (the direction in which the through hole 5 extends). It is a hole.

  The shape of the through-hole 5 is a straight hole in which the central axis 6 extends linearly, and the area of the cross section 7 perpendicular to the direction in which the central axis 6 extends varies from one main surface 4a to the other main surface 4b. As long as it increases towards, it is not limited. The area of the cross section 7 may increase continuously from the main surface 4a to the main surface 4b or may increase stepwise (that is, there may be a region where the area of the cross section 7 is constant). The area of the cross section 7 preferably increases continuously from the main surface 4a to the main surface 4b as in the example shown in FIG. 1 (the through hole 5 has an area of the cross section 7 from one main surface 4a. It is preferable to have a shape that continuously increases to the other main surface 4b), and it is more preferable that the increase rate is substantially constant or constant. According to the manufacturing method described later, the waterproof breathable membrane 1 including the polymer film 2 having the through holes 5 in which the area of the cross section 7 continuously increases from the main surface 4a toward the main surface 4b, and the area It is possible to form the waterproof gas-permeable membrane 1 having a substantially constant or constant increase rate.

  The shape of the cross section 7 of the through hole 5 is not particularly limited, and is, for example, a circle or an ellipse. At this time, the shape of the cross section 7 does not need to be a strict circle or ellipse, and for example, some shape disturbance due to unevenness of chemical etching performed by the manufacturing method described later can be allowed. The through-hole 5 has an area of the cross section 7 that continuously increases from the main surface 4a to the main surface 4b at a substantially constant or constant increase rate, and has a shape of the cross section 7 that is a circle or an ellipse. In this case, the shape of the through hole 5 is a cone or an elliptical cone having the central axis 6 as a center line, or a part thereof. According to the manufacturing method described later, it is possible to form the waterproof breathable membrane 1 including the polymer film 2 having the through hole 5 whose cross section 7 has a circular or elliptical shape.

  The ratio a / b between the diameter of the opening 8a (opening diameter a) and the diameter of the opening 8b (opening diameter b) in the through hole 5 is 80% or less, and the degree of freedom in controlling air permeability and waterproofness can be increased. Therefore, 75% or less is preferable, and 70% or less is more preferable. The lower limit of the ratio a / b is not particularly limited and is, for example, 10%.

  The degree of freedom of control of air permeability and waterproofness can be increased, more specifically, since waterproofness and air permeability can be compatible at a higher level, the diameter (opening diameter a) of the relatively small opening 8a. ) Is preferably 12 μm or less, more preferably 6 μm or less, and even more preferably 2 μm or less. On the other hand, the diameter (opening diameter b) of the opening 8b which is a relatively large opening is preferably 1 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. The lower limit of the opening diameters a and b is not particularly limited, but is 0.01 μm, for example. When the opening diameter a and / or the opening diameter b is excessively small, the air permeability as the waterproof gas-permeable membrane 1 is excessively lowered, and it is difficult to achieve both the air permeability and the water resistance.

  For the through-hole 5, the diameter of the circle when the shape of the openings 8a and 8b is regarded as a circle, in other words, the diameter of a circle having the same area as the cross-sectional area (opening area) of the openings 8a and 8b It is set as the opening diameter of opening 8a, 8b. Although the opening diameter of the through-hole 5 in each main surface of the polymer film 2 does not have to coincide with all the openings existing in the main surface, the effective portion of the polymer film 2 (used as the waterproof breathable membrane 1) It is preferable that it corresponds to a level that can be regarded as substantially the same value (for example, the standard deviation is 10% or less of the average value). According to the manufacturing method described later, it is possible to form the waterproof breathable membrane 1 having the same opening diameter on each main surface.

  In addition, the opening shape of the through-hole 5 extended in the direction inclined from the direction perpendicular | vertical to the main surfaces 4a and 4b of the polymer film 2 can be an ellipse. However, even in such a case, the shape of the cross section 7 of the through-hole 5 in the film 2 can be regarded as a circle, and the diameter of this circle is equal to the minimum diameter of the ellipse that is the opening shape. For this reason, in the case of the through hole 5 extending in the inclined direction and having an elliptical opening shape, the minimum diameter can be set as the opening diameter of the through hole.

The density (hole density) of the through holes 5 in the polymer film 2 is not particularly limited, and is, for example, 1 × 10 ³ pieces / cm ² or more and 1 × 10 ⁹ pieces / cm ² or less. When the pore density is within this range, it becomes easy to control the air permeability and the waterproof property within a preferable range for the waterproof gas-permeable membrane 1. Pore density, 1 × 10 ⁵ / cm ² or more 1 × 10 ⁸ / cm ² or less being more preferred. The pore density need not be constant throughout the polymer film 2, but in the effective portion of the polymer film 2, it is constant so that the maximum pore density is not more than 1.5 times the minimum pore density. It is preferable.

  The opening ratio of the opening 8a in the main surface 4a of the polymer film 2 (ratio of the opening area to the area of the main surface) is preferably 50% or less, preferably 10% or more and 45% or less, more preferably 20% or more and 40% or less. preferable. When the aperture ratio is within these ranges, it becomes easy to control the breathability and waterproofness within a range preferable as the waterproof breathable membrane 1. Note that a stretched porous membrane having a dispersed structure of innumerable pores generated by stretching cannot be a waterproof gas-permeable membrane having such a low porosity.

  In the waterproof breathable membrane 1 shown in FIG. 1, the central axis 6 of the through hole 5 extends in a direction perpendicular to the main surfaces 4 a and 4 b of the polymer film 2, but the extending direction of the central axis 6 of the through hole 5 is mainly You may incline from the direction perpendicular | vertical to the surface 4a, 4b. That is, the waterproof breathable membrane 1 may be composed of a polymer film 2 having a through hole 5 extending in a direction inclined from a direction perpendicular to the main surfaces 4a and 4b. An example of such a waterproof breathable membrane 1 is shown in FIG. In FIG. 2, the liquid repellent layer 3 is not shown (the same applies to FIGS. 3 and 6).

  In the waterproof gas-permeable membrane 1, through holes 5 having different extending directions of the central axis 6 may be mixed. More specifically, for example, in the polymer film 2, a through hole 5 in which the central axis 6 extends in a direction perpendicular to the main surfaces 4 a and 4 b, and a through hole 5 in which the central axis 6 extends in a direction inclined from the direction. May be mixed. Further, for example, the polymer film 2 has a through hole 5 in which the central axis 6 extends in a direction inclined from a direction perpendicular to the main surfaces 4 a and 4 b of the film 2, and the through holes 5 having different directions extending in the inclined direction are provided. It may be mixed in the polymer film 2. An example of the latter is shown in FIG.

  In the waterproof gas permeable membrane 1 shown in FIG. 3, the polymer film 2 includes through holes 5 a to 5 g having different directions extending with the central axis 6 inclined from a direction perpendicular to the main surfaces 4 a and 4 b. In other words, the through hole 5 in the waterproof breathable membrane 1 of FIG. 3 extends in a direction inclined with respect to the direction perpendicular to the main surfaces 4a and 4b of the polymer film 2 (through the polymer film 2). There are combinations of through holes 5 that extend in different directions. The polymer film 2 may have a combination of through holes 5 that extend in the same direction. In the example shown in FIG. 3, for example, the extending directions of the through holes 5a, 5b, and 5c are different from each other, and the extending directions of the through holes 5a and 5e are the same. Hereinafter, “combination” is also simply referred to as “set” in the present specification. The “set” is not limited to the relationship (pair) between one through hole and one through hole, and means a relationship between one or two or more through holes. Having a set of through holes having the same characteristics means that there are a plurality of through holes having the characteristics.

  As shown in FIG. 3, in the waterproof breathable membrane 1 composed of the polymer film 2 in which the through holes 5 having different directions extending at an inclination are mixed, the inclination degree and the ratio of the through holes 5 extending in a certain direction are changed. Therefore, the air permeability as the waterproof breathable membrane 1 and the degree of freedom in controlling the waterproof property are further increased.

  2 and 3, the angle θ1 formed by the direction D1 inclined and extending with respect to the direction D2 perpendicular to the main surface of the polymer film 2 is preferably 45 ° or less, and more preferably 30 ° or less. When the angle θ1 is within these ranges, the level at which both the air permeability and the waterproof property as the waterproof gas-permeable membrane 1 can be achieved becomes higher. Although the minimum of angle (theta) 1 is not specifically limited, For example, it is 10 degrees or more, and 20 degrees or more are preferable. If the angle θ1 is excessively large, the mechanical strength of the waterproof gas-permeable membrane 1 tends to be weakened. In the through hole 5 shown in FIG. 3, there are pairs having different angles θ1.

  As shown in FIG. 3, when the waterproof gas-permeable membrane 1 is composed of the polymer film 2 including the through-holes 5 having different directions extending at an angle, when viewed from a direction perpendicular to the main surface of the polymer film 2 ( When the direction in which the through hole 5 extends is projected onto the main surface), the direction in which the through hole 5 extends may be parallel to each other, but the polymer film 2 has a set having different extending directions (the extending). It is preferable that through holes 5 having different directions exist in the polymer film 2). In the case of the latter, the level which can make air permeability and waterproof property as the waterproof breathable film 1 compatible becomes higher.

  FIG. 4 shows an example in which the directions in which the through holes 5 extend are parallel to each other when viewed from a direction perpendicular to the main surface of the polymer film 2. In the example shown in FIG. 4, three through-holes 5 (5h, 5i, 5j) are visible, but the direction in which each through-hole 5 extends when viewed from a direction perpendicular to the main surface of the polymer film 2 (paper surface) D3, D4, and D5 are parallel to each other (the direction from the opening 8a of the through hole 5 on the front main surface to the opening 8b of the through hole 5 on the opposite main surface) (θ2 described later is 0 °). . However, the angle θ1 of each through hole 5h, 5i, 5j is different from each other, the angle θ1 of the through hole 5j is the smallest, and the angle θ1 of the through hole 5h is the largest. For this reason, the direction in which each through-hole 5h, 5i, 5j extends is three-dimensionally different.

  FIG. 5 shows an example in which the through-holes 5 extend in different directions when viewed from a direction perpendicular to the main surface of the polymer film 2. In the example shown in FIG. 5, three through holes 5 (5k, 5l, 5m) are visible, but the direction D6 in which each through hole 5 extends when viewed from a direction perpendicular to the main surface of the polymer film 2. D7 and D8 are different from each other. Here, the through holes 5k and 5l form an angle θ2 of less than 90 ° when viewed from a direction perpendicular to the main surface of the polymer film 2, and extend from the main surface in different directions. On the other hand, the through holes 5k and 5m form an angle θ2 of 90 ° or more when viewed from a direction perpendicular to the main surface of the polymer film 2, and extend from the main surface in different directions. Like the latter, the polymer film 2 has a set of through-holes 5 extending in different directions from the main surface at an angle θ2 of 90 ° or more when viewed from a direction perpendicular to the main surface of the film. It is preferable to have. In other words, when the polymer film 2 is viewed from a direction perpendicular to the main surface of the film, the polymer film 2 has a through hole 5k extending in a certain direction D6 from the main surface and 90 ° with respect to the certain direction D6. It is preferable to have a pair with the through hole 5m extending from the main surface in the direction D8 forming the angle θ2. At this time, the level at which the breathability and waterproofness as the waterproof breathable membrane 1 can be achieved is further increased. The angle θ2 is preferably 90 ° or more and 180 ° or less, that is, may be 180 °.

  As shown in FIG. 3, in the waterproof gas-permeable membrane 1 composed of the polymer film 2 in which the through-holes 5 having different tilting and extending directions are mixed, two or more through-holes 5 intersect each other in the polymer film 2. May be. That is, the polymer film 2 may have a set of through holes 5 that intersect with each other in the film 2. At this time, the level at which the breathability and waterproofness as the waterproof breathable membrane 1 can be achieved is further increased. Such an example is shown in FIG. In the example shown in FIG. 6, the through holes 5 p and 5 q intersect with each other in the polymer film 2.

  The extending direction of the through hole 5 (in the waterproof air-permeable membrane 1) in the polymer film 2 (the direction in which the central axis 6 of the through hole 5 extends) is, for example, a scanning electron microscope (SEM) with respect to the main surface and cross section of the film. ) To confirm.

  The polymer film 2 may have through-holes that are straight holes whose cross-sectional shape perpendicular to the direction in which the central axis extends is constant in the thickness direction of the film 2.

  The waterproof breathable membrane 1 may be subjected to a liquid repellent treatment. In the waterproof breathable membrane 1 subjected to the liquid repellent treatment, the liquid repellent layer 3 is formed on at least a part of the surface of the polymer film 2. In the example shown in FIG. 1, the liquid repellent layer 3 is formed on both main surfaces 4 a and 4 b of the polymer film 2 and the surface of the through hole 3. The liquid repellent layer 3 may be formed only on one main surface of the polymer film 2 or may be formed only on one main surface and the surface of the through hole 3. It is preferable that the liquid repellent layer 3 is formed on the main surface 4a having the opening 8a having a relatively small diameter.

  The liquid repellent layer 3 is a layer having water repellency, and preferably also has oil repellency. The liquid repellent layer 3 has an opening at a position corresponding to the through hole 5 of the polymer film 2.

  The liquid repellent layer 3 can be formed, for example, by thinly applying a treatment liquid prepared by diluting a water repellent or a hydrophobic oil repellent with a diluent and drying it on the polymer film 2. The water repellent and the hydrophobic oil repellent are, for example, fluorine compounds such as perfluoroalkyl acrylate and perfluoroalkyl methacrylate. The thickness of the liquid repellent layer 3 is preferably less than ½ of the diameter of the through hole 5.

  When the liquid repellent layer 3 is formed by thinly applying the treatment liquid on the polymer film 2, the surface (inner peripheral surface) of the through hole is also the main surface of the film 2 depending on the diameter of the through hole 5. It is possible to cover the surface continuously with the liquid repellent layer 3 (this is the case in the example shown in FIG. 1).

  The thickness of the polymer film 2 is, for example, 10 μm or more and 100 μm or less, and preferably 15 μm or more and 50 μm or less.

  The material which comprises the polymer film 2 is a material which can form the through-hole 5 in the original film which is a non-porous polymer film, for example in the below-mentioned manufacturing method. The polymer film 2 is made of, for example, an alkaline solution, an acidic solution, or a resin that is decomposed by an alkaline solution or an acidic solution to which at least one selected from an oxidizing agent, an organic solvent, and a surfactant is added. In this case, it becomes easier to form the through holes 5 in the original film by ion beam irradiation and chemical etching in the manufacturing method described later. These solutions are typical etching processing solutions. Viewed from another aspect, the polymer film 2 is made of a resin that can be etched by hydrolysis or oxidative decomposition, for example. A commercially available film can be used for the original film.

  The polymer film 2 is made of, for example, at least one resin selected from polyethylene terephthalate (PET), polycarbonate, polyimide, polyethylene naphthalate, and polyvinylidene fluoride.

  The waterproof gas-permeable membrane 1 may include a polymer film 2 having two or more layers. Such a waterproof gas-permeable membrane 1 can be formed by, for example, ion beam irradiation and chemical etching on a laminate having two or more original films.

  The waterproof gas-permeable membrane 1 preferably has an air permeability of 0.5 seconds or more in the thickness direction as indicated by a Gurley number (hereinafter simply referred to as “Gurley number”) measured in accordance with JIS L1096. Considering that the liquid repellent layer 3 does not substantially affect the air permeability, the polymer film 2 can have an air permeability of 0.5 seconds or more in the thickness direction as indicated by the Gurley number.

  The waterproof breathable membrane 1 preferably has a water pressure of 5 kPa or more, more preferably 10 kPa or more, more preferably 20 kPa or more, measured in accordance with the provisions of the water resistance test method B (high water pressure method) of JIS L1092. More preferably it is. The water pressure resistance of 10 kPa means that the water pressure can withstand a water depth of 1 m. In this case, waterproofness corresponding to “water protection class 7 (IPX7)” defined in JIS C0920 is ensured. Even when the electronic device equivalent to IPX7 is accidentally dropped into the water, it can avoid inundation into the device within a predetermined depth and time. Further, it is empirically known that when the water pressure resistance is about 5 kPa, waterproofing equivalent to “water protection class 4 (IPX4)” defined in JIS C0920 is secured. IPX4 is also one of the waterproof properties required for electronic devices in recent years.

  Since the waterproof breathable membrane 1 has different diameters of the openings 8a and 8b of the through holes 5 in both the main surfaces 4a and 4b of the polymer film 2 constituting the membrane 1, the one side of the main surface 4a of the polymer film 2 From the other main surface 4b side to the one main surface 4a side is different from that of the other main surface 4b side. More specifically, the waterproofness from the one main surface 4a side where the opening diameter of the through-hole 5 is relatively small is compared with the waterproofness from the one main surface 4b side where the opening diameter is relatively large. large. It is preferable that the waterproofness from the one main surface 4a side where the opening diameter of the through-hole 5 is relatively small is 5 kPa or more in terms of the water pressure resistance. The difference between the water pressure resistance of the waterproof gas-permeable membrane 1 from the main surface 4a side and the water pressure resistance of the waterproof gas-permeable membrane 1 from the main surface 4b side is preferably 5 kPa or more, and more preferably 10 kPa or more. The degree of the difference in waterproofness of the waterproof breathable membrane 1 due to the main surfaces 4a and 4b is determined by the shape of the through-hole 5 of the polymer film 2, more specifically, the opening diameter of the through-hole 5 and the above ratio. It can be controlled by a / b. Further, when the waterproof gas-permeable membrane 1 has two or more polymer films 2, the configuration of each polymer film 2 and the laminated state of the two or more polymer films 2 (for each polymer film 2 in the laminated state) The main surface 4a, 4b can be controlled by the main surface side of the waterproof gas-permeable membrane 1). The fact that such control is possible also contributes to a high degree of freedom in controlling waterproofness of the waterproof breathable membrane 1.

  The waterproof gas-permeable membrane 1 can achieve these preferable air permeability and water pressure resistance at the same time.

  The waterproof gas-permeable membrane 1 may include an arbitrary member and / or layer other than the polymer film 2 and the liquid repellent layer 3 as necessary. The member is, for example, a breathable support layer 9 shown in FIG. In the waterproof gas-permeable membrane 1 shown in FIG. 7, the air-permeable support layer 9 is disposed on the other main surface 4b of the polymer film 2 of the waterproof gas-permeable membrane 1 shown in FIG. By the arrangement of the air-permeable support layer 9, the strength as the waterproof gas-permeable membrane 1 is improved, and the handleability is also improved. The breathable support layer 9 may be disposed on one main surface 4a of the polymer film 2 or may be disposed on both main surfaces 4a and 4b.

  The breathable support layer 9 is a layer having a higher air permeability in the thickness direction than the polymer film 2. For the breathable support layer 9, for example, a woven fabric, a nonwoven fabric, a net, or a mesh can be used. The material constituting the air-permeable support layer 9 is, for example, polyester, polyethylene, or aramid resin. The liquid repellent layer 3 may or may not be formed on the main surface of the polymer film 2 on which the air-permeable support layer 9 is disposed. The shape of the air-permeable support layer 9 may be the same as or different from the shape of the polymer film 2. For example, the air-permeable support layer 9 has a shape that is arranged only at the peripheral edge of the polymer film 2 (specifically, when the polymer film is circular, it has a ring shape that is arranged only at the peripheral edge). It can be. The air-permeable support layer 9 is disposed by a technique such as thermal welding with the polymer film 2 or adhesion with an adhesive.

The surface density of the waterproof gas-permeable membrane 1 is preferably 5 to 100 g / m ^{2 and} more preferably 10 to 50 g / m ² from the viewpoint of the strength and handleability of the membrane.

  The thickness of the waterproof gas-permeable membrane 1 is, for example, 10 to 100 μm, and preferably 15 to 50 μm.

  The waterproof breathable membrane 1 may be subjected to a coloring treatment. Depending on the type of material constituting the polymer film 2, the color of the waterproof breathable membrane 1 that has not been colored is, for example, transparent or white. When such a waterproof gas-permeable membrane 1 is arranged so as to close the opening of the housing, the membrane 1 may stand out. The conspicuous membrane stimulates the user's curiosity, and the function as a waterproof breathable membrane may be impaired by piercing with a needle or the like. When the waterproof gas-permeable membrane 1 is colored, for example, by using the membrane 1 having the same color or a color similar to the color of the housing, the user's attention can be relatively suppressed. In addition, a colored waterproof breathable membrane may be required due to the design of the housing, and such a design requirement can be met by the coloring process.

  The coloring process can be performed by, for example, dyeing the polymer film 2 or adding a colorant to the polymer film 2. For example, the coloring treatment may be performed so that light included in a wavelength range of 380 nm to 500 nm is absorbed. That is, the waterproof gas-permeable membrane 1 may be subjected to a coloring treatment that absorbs light included in a wavelength range of 380 nm to 500 nm. For this purpose, for example, the polymer film 2 contains a colorant having the ability to absorb light included in the wavelength range of 380 nm to 500 nm, or absorbs light included in the wavelength range of 380 nm to 500 nm. Dyed with a dye having the ability to In this case, the waterproof gas-permeable membrane 1 can be colored blue, gray, brown, pink, green, yellow, or the like. The waterproof air-permeable membrane 1 may be colored in black, gray, brown or pink.

  The waterproof gas-permeable membrane 1 can be used in various applications, for example, a waterproof ventilation member and a waterproof ventilation structure.

  The manufacturing method of the waterproof breathable film 1 comprised from the polymer film 2 which has the through-hole 5 is not specifically limited, For example, it can manufacture with the manufacturing method demonstrated below.

[Method for producing waterproof breathable membrane]
In the following manufacturing method, the polymer film 2 is formed by ion beam irradiation on the original film and subsequent chemical etching. The polymer film 2 formed by ion beam irradiation and chemical etching may be used as the waterproof gas-permeable membrane 1 as it is, or through a further process such as a liquid repellent treatment, a coloring treatment, or a step of laminating the air-permeable support layer 9. It may be 1.

  In the method using ion beam irradiation and subsequent chemical etching, the opening diameters of the through holes 5 of the polymer film 2 can be made uniform to the above-described preferable degree on the respective main surfaces 4a or 4b.

  The original film is a non-porous polymer film that does not have a path that allows ventilation in the thickness direction in the region used as the waterproof gas-permeable membrane 1 after ion beam irradiation and chemical etching. The original film may be a non-porous film.

  When the original film is irradiated with an ion beam, the polymer chain constituting the polymer film is damaged by collision with the ions in the portion where the ions pass in the film. Damaged polymer chains are more susceptible to chemical etching than other portions of the polymer chain that are not colliding with ions. For this reason, by chemically etching the original film irradiated with the ion beam, a polymer film having pores (through-holes) extending along the trajectory of ion collision can be obtained. That is, the direction in which the central axis 6 of the through hole 5 extends is the direction in which ions have passed through the original film during ion beam irradiation. In addition, a pore is not normally formed in the part which the ion in the original film has not passed.

  As described above, in the manufacturing method of the present disclosure, the method of forming the polymer film 2 from the original film includes the step (I) of irradiating the original film with the ion beam and the portion where the ions collide with the original film after the ion beam irradiation. (II), in which at least a part of the film is chemically etched to form a through hole 5 extending along a trajectory (ion track) of ion collision in the film. And in process (II), by arrangement | positioning of the masking layer to one main surface in the original film after ion irradiation, compared with the etching of the said part from the said one main surface, the other in the original film after ion irradiation Chemical etching is performed with a large degree of etching of the portion from the main surface. In this chemical etching, the degree of etching of the ion track from the other main surface is larger than that of the ion track from the one main surface on which the masking layer is disposed. By performing such asymmetric etching, more specifically, etching with different traveling speeds from one main surface and the other main surface in the original film after ion irradiation, the central axis 6 The area of the cross section 7 perpendicular to the extending direction of the polymer film 2 has a shape that increases from one main surface to the other main surface of the polymer film 2, and has an opening diameter a on one main surface and an opening on the other main surface. A through hole 5 having a ratio a / b with the diameter b of 80% or less can be formed. In Patent Document 2, since uniform etching proceeds as a result from both main surfaces of the original film after ion beam irradiation, the cross-sectional shape of the through hole is constant in the film thickness direction. A film is formed.

  Hereinafter, steps (I) and (II) will be described more specifically.

[Step (I)]
In step (I), the original film is irradiated with an ion beam. The ion beam is composed of accelerated ions. By irradiating the ion beam, an original film in which ions in the beam collide is formed.

  When the original film is irradiated with the ion beam, as shown in FIG. 8, the ions 21 in the beam collide with the original film 22, and the collided ions 21 leave a locus 23 (ion track) inside the film 22. When viewed on the size scale of the original film 22 that is the object to be irradiated, the ions 21 usually collide with the original film 22 in a substantially straight line, so that a linearly extending locus 23 is formed in the film 22. The ions 21 usually penetrate the original film 22.

  The method of irradiating the original film 22 with an ion beam is not limited. For example, after the original film 22 is accommodated in the chamber and the pressure in the chamber is reduced (for example, after a high vacuum atmosphere is set to suppress the attenuation of energy of the irradiated ions 21), the ions 21 are generated from the beam line. Irradiate the film 22. A specific gas may be added to the chamber, or the original film 22 may be accommodated in the chamber, but the pressure in the chamber may not be reduced, and for example, ion beam irradiation may be performed at atmospheric pressure.

  A roll around which the strip-shaped original film 22 is wound may be prepared, and the original film 22 may be continuously irradiated with an ion beam while the original film 22 is sent out from the roll. Thereby, the polymer film 2 can be formed efficiently. The roll (delivery roll) and the take-up roll that winds up the original film 22 after irradiation with the ion beam are arranged in the chamber described above, and the belt is stripped from the delivery roll in an arbitrary atmosphere such as reduced pressure or high vacuum. While the original film 22 is being fed out, the film may be continuously irradiated with an ion beam, and the original film 22 after the beam irradiation may be wound on a take-up roll.

  The resin constituting the original film 22 is the same as the resin constituting the polymer film 2 and is, for example, at least one selected from PET, polycarbonate, polyimide, polyethylene naphthalate, and polyvinylidene fluoride. The original film 22 composed of these resins has a feature that the chemical etching of the portion where the ions 21 collide proceeds smoothly but the chemical etching of the other portion is difficult to proceed. Control of the chemical etching of the portion corresponding to the locus 23 becomes easy. For this reason, use of such an original film 22 makes it easier to control the shape of the through-hole 5 of the polymer film 2, for example.

  The original film 22 may be composed of two or more kinds of resins, and may contain materials other than the resin as long as the polymer film 2 is formed through the steps (I) and (II). Examples of the material include additives such as a light stabilizer and an antioxidant, an oligomer component derived from a resin raw material, and a metal oxide (for example, white pigment: alumina, titanium oxide, and the like).

  The thickness of the original film 22 is, for example, 10 to 100 μm. Usually, the thickness of the original film 22 does not change depending on before and after the ion beam irradiation in the step (I).

  The original film 1 that is irradiated with an ion beam is, for example, a non-porous film. In this case, a portion other than the through holes 5 formed by the steps (I) and (II) is non-porous unless a further step of forming holes in the film other than the steps (I) and (II) is performed. A molecular film 2 can be formed. When the said further process is implemented, the polymer film 2 which has the through-hole 5 formed by process (I) and (II) and the hole formed by the said further process is formed.

  The type of ions 21 that are irradiated and collide with the original film 22 is not limited. However, since the chemical reaction with the resin constituting the original film 22 is suppressed, ions having a mass number greater than that of neon, specifically, argon. At least one ion selected from ions, krypton ions and xenon ions is preferred.

  The energy (acceleration energy) of the ions 21 is typically 100 to 1000 MeV. When a polyester film having a thickness of about 10 to 100 μm is used as the original film 22, the energy of the ions 21 when the ion species is argon ions is preferably 100 to 600 MeV. The energy of the ions 21 irradiated to the original film 22 can be adjusted according to the ion species and the type of resin constituting the original film 22.

  The ion source of the ions 21 irradiated to the original film 22 is not limited. The ions 21 emitted from the ion source are, for example, accelerated by an ion accelerator and then irradiated to the original film 22 through a beam line. The ion accelerator is, for example, a cyclotron, and a more specific example is an AVF cyclotron.

The pressure of the beam line serving as the path of the ions 21 is preferably a high vacuum of about 10 ⁻⁵ to 10 ⁻³ Pa from the viewpoint of suppressing energy attenuation of the ions 21 in the beam line. When the pressure of the chamber in which the original film 22 that irradiates the ions 21 is not high vacuum, the pressure difference between the beam line and the chamber may be maintained by a partition wall that transmits the ions 21. The partition is made of, for example, a titanium film or an aluminum film.

  The ions 21 are irradiated to the film from a direction perpendicular to the main surface of the original film 22, for example. In the example shown in FIG. 8, such irradiation is performed. In this case, since the trajectory 23 extends perpendicularly to the main surface of the original film 22, a through hole 5 extending the central axis 6 in a direction perpendicular to the main surface is formed by subsequent chemical etching, as shown in FIG. A polymer film 2 is obtained. The ions 21 may be applied to the film from a direction oblique to the main surface of the original film 22. In this case, the polymer film 2 as shown in FIG. 2 in which the through hole 5 is formed by extending the central axis 6 in the direction inclined from the direction perpendicular to the main surface is obtained by subsequent chemical etching. The direction in which the original film 22 is irradiated with the ions 21 can be controlled by a known means. 2 can be controlled by, for example, the incident angle of the ion beam with respect to the original film 22.

  For example, the ions 21 are irradiated on the original film 22 so that tracks of the plurality of ions 21 are parallel to each other. In the example shown in FIG. 8, such irradiation is performed. In this case, a polymer film 2 as shown in FIGS. 1 and 2 in which a plurality of through holes 5 extending in parallel with each other is formed by subsequent chemical etching.

  The ions 21 may be irradiated to the original film 22 so that the tracks of the plurality of ions 21 are not parallel to each other (for example, random to each other). Thereby, for example, a polymer film 2 as shown in FIGS. 3 to 6 is formed. More specifically, in order to form the polymer film 2 as shown in FIGS. 3 to 6, for example, the ion beam is irradiated while being tilted from a direction perpendicular to the main surface of the original film 22, and continuously or in stages. Alternatively, the direction of tilting may be changed. Since the ion beam is a beam in which a plurality of ions fly in parallel with each other, a set of through holes 5 extending in the same direction usually exists in the polymer film 2 (a plurality of through holes 5 extending in the same direction are present). Usually present in the polymer film 2).

  FIG. 9 shows an example of a method for changing the tilt direction continuously or stepwise. In the example shown in FIG. 9, the strip-shaped original film 22 is sent out from the delivery roll 31, passed through an irradiation roll 32 having a predetermined curvature, irradiated with an ion beam 33 while passing through the roll 32, and the original after irradiation. The film 22 is taken up on a take-up roll 34. At this time, since the ions 21 in the ion beam 33 fly one after another in parallel, the angle at which the ion film collides with the main surface of the original film 22 while the original film 22 moves on the irradiation roll 32 ( The incident angle θ1) will change. When the ion beam 33 is continuously irradiated, the tilt direction changes continuously, and when the ion beam 33 is intermittently irradiated, the tilt direction changes stepwise. This can be said to be control by the irradiation timing of the ion beam. The state of the locus 23 formed on the original film 22 (for example, the angle θ1) can also be controlled by the sectional shape of the ion beam 33 and the sectional area of the beam line of the ion beam 33 with respect to the irradiation surface of the original film 22.

  The pore density of the polymer film 2 can be controlled by ion beam irradiation conditions (ion species, ion energy, ion collision density (irradiation density), etc.) on the original film 22.

  The ions 21 may be irradiated to the original film 22 from two or more beam lines.

  Step (I) may be performed in a state where the masking layer is disposed on the main surface of the original film 22, for example, the one main surface.

[Step (II)]
In the step (II), at least a part of the portion of the original film 22 that has collided with the ions 21 in the step (I) is chemically etched to penetrate along the trajectory 23 of the collision of the ions 21. Holes 5 are formed in the film. The portions other than the through-holes 5 in the polymer film 2 thus obtained are basically the same as the original film 22 before the ion beam irradiation unless a step of changing the state of the film is further performed.

  Further, in the step (II), the chemical etching is performed in a state where the masking layer is disposed on one main surface of the original film 22 after the ion beam irradiation. In this chemical etching, the etching of the portion of the original film 22 where the ions 21 collide is greater in the degree of etching from the other main surface than in the etching from the one main surface where the masking layer is disposed. That is, in the step (II), chemical etching (asymmetric etching) in which etching from both main surfaces of the film proceeds asymmetrically with respect to the etching of the portion of the original film 22 where the ions 21 collide is performed. More specifically, “the degree of etching is large” means, for example, that the etching amount per unit time is large for the part, that is, the etching rate is high for the part.

  In the step (II), the above-mentioned portion from the one main surface is arranged on the one main surface of the original film 22 by disposing a masking layer that is hard to be chemically etched compared to the portion where the ions 21 collide with the original film 22. You may implement the chemical etching which advances the etching of the said part from the other main surface of the original film 22, suppressing etching. Such etching can be performed, for example, by selecting the type and thickness of the masking layer, disposing the masking layer, selecting etching conditions, and the like.

  Although the kind of masking layer is not specifically limited, It is preferable that it is a layer comprised from the material which is hard to be chemically etched compared with the part which the ion 21 collided in the original film 22. FIG. More specifically, “not easily etched” means, for example, that the amount etched per unit time is small, that is, the etching rate is small. Whether or not chemical etching is difficult can be determined based on the conditions of the asymmetric etching actually performed in the step (II) (the type of etching solution, etching temperature, etching time, etc.). As will be described later, when the asymmetric etching is performed a plurality of times in the step (II) while changing the type and / or arrangement surface of the masking layer, each etching may be determined based on the etching conditions.

  The masking layer may be either more or less likely to be chemically etched than the portion of the original film 22 where the ions 21 do not collide, but it is preferable that the masking layer is less likely to be. If it is difficult to do so, for example, the thickness of the masking layer required to perform asymmetric etching can be reduced.

  In the step (I), when the ion film is irradiated to the original film 22 on which the masking layer is arranged, ion tracks are also formed on the masking layer. Considering this, it is preferable that the material constituting the masking layer is a material in which the polymer chain is hardly damaged even by irradiation with an ion beam.

  The masking layer is composed of at least one selected from, for example, polyolefin, polystyrene, polyvinyl chloride, polyvinyl alcohol, and metal foil. These materials are difficult to be chemically etched and are not easily damaged by ion beam irradiation.

  What is necessary is just to arrange | position a masking layer in at least one part of one main surface of the original film 22 corresponded to the area | region which implements asymmetrical etching. Of course, it can arrange | position to the whole one main surface of the original film 22 as needed.

  The method of disposing the masking layer on the main surface of the original film 22 is not limited as long as the masking layer does not peel off from the main surface during the asymmetric etching. The masking layer is disposed on the main surface of the original film 22 with an adhesive, for example. That is, in the step (II), the chemical etching (asymmetric etching) may be performed in a state where the masking layer is bonded to the one main surface with an adhesive. The arrangement of the masking layer with the pressure-sensitive adhesive can be performed relatively easily. Further, by selecting the type of the pressure-sensitive adhesive, the masking layer can be easily peeled off from the original film 22 after the asymmetric etching.

  In step (II), asymmetric etching may be performed a plurality of times. Further, as long as at least one asymmetric etching is performed, symmetric etching may be performed in which the etching of the trajectory 23 progresses equally from both main surfaces of the original film 22. For example, the masking layer may be peeled off from the polymer film 1 in the course of etching to switch from asymmetric etching to symmetric etching. Alternatively, the asymmetric etching may be performed by arranging the masking layer after performing the symmetric etching.

  When asymmetric etching is performed a plurality of times, the etching conditions may be changed in each etching.

  FIG. 10 shows an example of the step (II).

  In the example shown in FIG. 10, a masking layer 41 is disposed on one main surface of the original film 22 after the ion beam irradiation (FIG. 10A), and chemical etching is performed in this state. As a result, etching proceeds along the locus 23 formed by ion beam irradiation from the other surface where the masking layer is not disposed, and the through-hole 5 extending along the locus 23 is formed (FIG. 10). (B)). As shown in FIG. 10B, the etching does not proceed from the main surface on which the masking layer 41 is disposed, and no pores are formed. The cross-section of the formed through-hole 5 has a conical shape, and the tip of the through-hole 5 opens on the one main surface of the original film 22. And the opening diameter in the said one main surface of the through-hole 5 and the opening diameter in the other main surface are mutually different, and the opening diameter in the said other main surface used as the etching origin is larger. That is, in the example shown in FIG. 10, a polymer film 2 having a through hole having a conical cross-sectional shape and having an opening diameter different between both main surfaces of the film is obtained. (FIG. 10 (c)). The ratio a / b between the opening diameter a of the through hole 5 on the one main surface and the opening diameter b of the through hole 5 on the other main surface is 80% or less, and the etching performed in the step (II) is performed. Depending on the conditions, this ratio can be even smaller.

  Thus, in the step (II), the ratio of the opening diameter a on one main surface of the film to the opening diameter b on the other main surface is a through hole 5 whose hole diameter is changing in the film thickness direction. A through hole 5 having a / b of 80% or less can be formed. The direction in which the central axis 6 of the through hole 5 extends is the direction in which the locus 23 extends.

  In the example shown in FIG. 10, since asymmetric etching has already been performed once, chemical etching may be further advanced from the state where the masking layer 41 shown in FIG. Thereby, for example, the ratio a / b of the opening diameter of the through hole 5 or the opening diameter a of the through hole 5 on one main surface of the polymer film 2 and the opening diameter b of the through hole 5 on the other main surface. Can be controlled.

  The opening diameter of the through-hole 5 can also be controlled by the etching conditions such as the etching temperature, the etching time, and the composition of the etching treatment liquid.

  The polymer film 2 having the through holes 5 cannot be formed by a conventional method.

  The etching process liquid used for chemical etching is not specifically limited. The etching solution is, for example, an alkaline solution, an acidic solution, or an alkaline solution or an acidic solution to which at least one selected from an oxidizing agent, an organic solvent, and a surfactant is added. The alkaline solution is, for example, a solution (typically an aqueous solution) containing a base such as sodium hydroxide or potassium hydroxide. The acidic solution is, for example, a solution (typically an aqueous solution) containing an acid such as nitric acid or sulfuric acid. Examples of the oxidizing agent include potassium dichromate, potassium permanganate, and sodium hypochlorite. The organic solvent is, for example, methanol, ethanol, 2-propanol, ethylene glycol, amino alcohol, N-methylpyrrolidone, N, N-dimethylformamide. The surfactant is, for example, an alkyl benzene sulfonate or an alkyl sulfate.

  Except for the asymmetric etching using the masking layer 41, a specific etching method may follow a known method. For example, the beam-irradiated original film 22 in which the masking layer 41 is disposed may be immersed in an etching treatment solution at a predetermined temperature for a predetermined time.

  The etching temperature is, for example, 40 to 150 ° C., and the etching time is, for example, 10 seconds to 60 minutes.

  After step (II), part or all of the masking layer 41 can be left on the polymer film 2 as necessary. The remaining masking layer 41 can be used, for example, as a mark for distinguishing the one main surface (the main surface on which the masking layer is disposed) and the other main surface of the polymer film 2.

  The manufacturing method of the polymer film 2 may include any step other than the steps (I) and (II).

[Waterproof ventilation member]
An example of the waterproof ventilation member of the present invention is shown in FIG. A waterproof ventilation member 11 shown in FIG. 11 has a waterproof ventilation membrane 1 having a circular shape when viewed from a direction perpendicular to the main surface of the membrane, and a support body that is a ring-shaped sheet joined to the peripheral edge of the membrane 1. 51. The form in which the support body 51 is joined to the waterproof gas-permeable membrane 1 reinforces the waterproof gas-permeable membrane 1 and improves its handleability. Moreover, since the support body 51 becomes an allowance to the part to arrange | position the waterproof ventilation member 11, such as opening of a housing | casing, the attachment operation | work of the waterproof ventilation film 1 becomes easy.

  The shape of the support body 51 is not limited. For example, as shown in FIG. 12, even if it is the support body 51 which is a frame-shaped sheet | seat joined to the peripheral part of the waterproof breathable film 1 whose shape seen from the direction perpendicular | vertical to the main surface of a film | membrane is a rectangle. Good. As shown in FIGS. 11 and 12, by making the shape of the support 51 the shape of the peripheral portion of the waterproof gas-permeable membrane 1, a decrease in the air permeability of the waterproof gas-permeable membrane 1 due to the arrangement of the support 51 is suppressed. Moreover, the sheet-like support body 51 is preferable from the viewpoint of improving the handleability of the waterproof ventilation member 11 and the disposition property to the housing, particularly the disposition property within the housing.

  The material which comprises the support body 51 is resin, a metal, and these composite materials, for example. The resin is, for example, a polyolefin such as polyethylene or polypropylene; a polyester such as PET or polycarbonate; a polyimide or a composite material thereof. The metal is a metal having excellent corrosion resistance, such as stainless steel or aluminum.

  The thickness of the support 51 is, for example, 5 to 500 μm, and preferably 25 to 200 μm. When attention is paid to the function as an attachment margin, the ring width (frame width: difference between the outer shape and the inner diameter) is suitably about 0.5 to 2 mm. For the support 51, a foam made of the above resin may be used.

  The joining method of the waterproof gas-permeable membrane 1 and the support 51 is not particularly limited, and for example, methods such as heat welding, ultrasonic welding, adhesion using an adhesive, and adhesion using a double-sided tape can be employed.

  The direction of the waterproof gas-permeable membrane 1 in the waterproof gas-permeable member 11 (the direction of the main surface of the polymer film 2 included in the waterproof gas-permeable membrane 1) is not limited. For example, when the waterproof ventilation member 11 is fixed to the opening of the housing, the main surface 4a of the polymer film 2 (the opening diameter of the through hole 5 is relatively relative to the outside of the housing where water may enter). The waterproof breathable membrane 1 and the support body 51 may be joined so that the small main surface 4a) faces toward the bottom. In this case, higher waterproofness of the housing and higher air permeability can be ensured.

  The waterproof ventilation member 11 may include two or more waterproof ventilation membranes 1 and / or two or more supports 51.

  The waterproof ventilation member 11 can be used for the same application as the conventional waterproof ventilation member.

[Waterproof ventilation structure]
An example of the waterproof ventilation structure of the present invention is shown in FIG. The waterproof ventilation structure 12 shown in FIG. 13 includes a casing 81 provided with an opening 82 for allowing gas to pass between the inside 83 and the outside, and a waterproof ventilation film 1 disposed so as to close the opening (opening) 82. With. The waterproof breathable membrane 1 can prevent water from entering the casing 81 from the outside through the opening 82 while allowing gas to pass between the outside and the inside 83 of the casing 81. In the example shown in FIG. 13, the waterproof gas-permeable membrane 1 is bonded to the housing 81 via the support body 51. In other words, the waterproof ventilation member 11 including the waterproof ventilation membrane 1 and the support body 51 is joined to the housing 81. In the example shown in FIG. 13, the waterproof gas-permeable membrane 1 is joined to the housing 81 from the inside 83 of the housing 81, but may be joined from the outside of the housing 81.

  The casing 81 is made of resin, metal, glass, and a composite material thereof.

  For the arrangement of the waterproof gas-permeable membrane 1, techniques such as sticking using double-sided tape, thermal welding, high-frequency welding, and ultrasonic welding can be employed. The support 51 may be a double-sided tape.

  The direction of the waterproof gas-permeable membrane 1 in the waterproof gas-permeable structure 12 (the direction of the main surface of the polymer film 2 provided in the waterproof gas-permeable membrane 1) is not limited. For example, the main surface 4a of the polymer film 2 (the main surface 4a having a relatively small opening diameter of the through hole 5) faces the outside of the housing 81 having the waterproof ventilation structure 12, and the polymer film faces the inside of the housing 81. The waterproof air-permeable membrane 1 may be arranged so that the main surface 4b of 2 (the main surface 4b having a relatively large opening diameter of the through hole 5) faces. In this case, the waterproof property of the higher waterproof ventilation structure 12 and the higher air permeability from the inside of the housing 81 can be ensured.

  Parts, devices, devices, products, etc. having the waterproof ventilation structure 12 are not limited.

  The waterproof ventilation structure 12 can be applied to various uses like the conventional waterproof ventilation structure.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

  Initially, the evaluation method of the polymer film and waterproof breathable film which were produced in the Example and the comparative example is demonstrated.

[Opening diameter of through hole]
Both main surfaces of the polymer film were observed with a scanning electron microscope (SEM), and the opening diameters of 10 through holes arbitrarily selected from the obtained SEM images were obtained from the images for each main surface, and the average The value was the opening diameter of the through hole in the polymer film.

[Air permeability]
The air permeability in the thickness direction of the waterproof air-permeable membrane was determined in accordance with the provisions of JIS L1096 (Breathability measurement method A: Gurley method).

[Water pressure resistance]
The water pressure resistance of the waterproof breathable membrane was determined in accordance with the provisions of the water resistance test method B (high water pressure method) of JIS L1092. However, since the membrane is significantly deformed in the area of the test piece indicated in this regulation, a stainless steel mesh (opening diameter 2 mm) is placed on the opposite side of the pressure surface of the membrane, and measurement is performed with the membrane deformed to some extent. did.

[Pore density]
The pore density of the polymer film is obtained by observing both main surfaces of the film with an SEM, visually counting the number of through holes in the obtained SEM image, and converting this to a value per unit area. It was.

[Oil repellency]
The oil repellency of the waterproof breathable membrane was evaluated as follows. Place the waterproof breathable membrane and copy paper (plain paper) on top of each other so that the waterproof breathable membrane is on top and the copy paper is on the bottom, drop a drop of castor oil on the waterproof breathable membrane with a dropper, and leave for 1 minute did. Thereafter, the waterproof breathable film was removed, and the state of the copy paper was confirmed. When the copy paper was wet with castor oil, the waterproof breathable film was not oil-repellent, and when it was not wet, the oil-repellent was given.

Example 1
A non-porous commercially available PET film (it4ip, Track etched membrane, thickness 50 μm) in which a plurality of through holes penetrating in the thickness direction was formed was prepared. This film is a film produced by irradiating a non-porous PET film with an ion beam and chemically etching the irradiated film. When the surface and cross section of this film were observed by SEM, (1) the through hole had a diameter of 0.25 μm and the area of the cross section perpendicular to the direction in which the central axis extends did not change in the film thickness direction. It is a straight hole (constant), (2) the through hole extends in a direction perpendicular to the main surface of the film, and (3) the hole density is 2.0 × 10 ⁶ holes / cm ^2. It was confirmed that

  Next, a polyethylene film (thickness: 55 μm) was attached to one main surface of the prepared PET film with an acrylic adhesive as a masking layer. This was immersed in an etching treatment liquid maintained at 80 ° C. (an aqueous solution having an ethanol concentration of 30 mass% and a potassium hydroxide concentration of 10 mass%) for 25 minutes. After completion of the etching, the film was taken out from the treatment liquid, immersed in RO water (reverse osmosis membrane filtered water), washed, and then dried in a drying oven at 50 ° C. Thereafter, the masking layer was peeled off to obtain the polymer film 2 in which the through holes 5 were formed.

  FIGS. 14 and 15 show the state of the surface of the obtained polymer film 2 (observed image by a scanning electron microscope (SEM)). FIG. 14 shows a main surface (masking surface) on which a masking layer is arranged, and FIG. 15 shows a main surface (etching surface) on which no masking layer is arranged. The magnifications in FIGS. 14 and 15 are the same. As shown in FIGS. 14 and 15, the polymer film obtained in Example 1 has a cross-sectional area perpendicular to the direction in which the central axis extends from one main surface (masking surface) to the other main surface (etching surface). It was confirmed that the film has a through hole having a shape that increases toward the surface. Moreover, the opening diameter of the through-hole in each main surface calculated | required from the said SEM image was 1.6 micrometers about the masking surface, and 3.2 micrometers about the etching surface, ie, ratio a / b was 50%.

  Next, after the liquid repellent treatment liquid is applied to the entire surface including both main surfaces of the produced polymer film 2, it is left to dry at room temperature for 30 minutes, and the surface of the film 2 and the inner peripheral surface of the through-hole 5 The liquid-repellent layer 3 was formed on the waterproof breathable membrane 1. The liquid repellent treatment liquid was prepared by diluting a liquid repellent (X-70-029C, manufactured by Shin-Etsu Chemical Co., Ltd.) with a diluent (manufactured by Shin-Etsu Chemical Co., Ltd., FS thinner) so as to have a concentration of 0.7% by weight.

  The waterproof breathable membrane 1 thus obtained had an air permeability (Gurley number) of 14 seconds, a water pressure resistance of 25 kPa on the masking surface side, 15 kPa on the etching surface side, and oil repellency “Yes”.

(Example 2)
Chemical etching was carried out in the same manner as in Example 1 except that the etching solution was changed to an aqueous solution having an ethanol concentration of 20% by mass and a potassium hydroxide concentration of 15% by mass to obtain a polymer film. The opening diameter of the through hole in each main surface of the polymer film thus obtained was 4.0 μm for the masking surface and 5.0 μm for the etching surface, that is, the ratio a / b was 80%.

  Next, the produced polymer film was subjected to a liquid repellent treatment in the same manner as in Example 1. The waterproof breathable membrane thus obtained had an air permeability (Gurley number) of 1.5 seconds, the water pressure resistance was 13 kPa on the masking surface side, 8 kPa on the etching surface side, and the oil repellency was “Yes”.

(Comparative Example 1)
Chemical etching was carried out in the same manner as in Example 1 except that the masking layer was not disposed and that the chemical etching was performed for 10 minutes to obtain a polymer film. Thus, the opening diameter of the through-hole in each main surface of the polymer film obtained was 1.6 micrometers about any main surface.

  Next, the produced polymer film was subjected to a liquid repellent treatment in the same manner as in Example 1. The waterproof breathable membrane thus obtained had an air permeability (Gurley number) of 66 seconds, a water pressure resistance of 25 kPa on all main surfaces, and an oil repellency of “Yes”.

(Comparative Example 2)
A chemical film was obtained in the same manner as in Example 1 except that the masking layer was not disposed and that the chemical etching was performed for 20 minutes. Thus, the opening diameter of the through-hole in each main surface of the polymer film obtained was 3.2 micrometers in any main surface.

  Next, the produced polymer film was subjected to a liquid repellent treatment in the same manner as in Example 1. The waterproof breathable membrane thus obtained had an air permeability (Gurley number) of 6 seconds, a water pressure resistance of 9 kPa on all main surfaces, and an oil repellency of “Yes”.

(Comparative Example 3)
Chemical etching was carried out in the same manner as in Example 2 except that the masking layer was not disposed and that the chemical etching was performed for 15 minutes to obtain a polymer film. Thus, the opening diameter of the through-hole in each main surface of the polymer film obtained was 4.0 micrometers in any main surface.

  Next, the produced polymer film was subjected to a liquid repellent treatment in the same manner as in Example 1. The waterproof breathable membrane thus obtained had an air permeability (Gurley number) of 4.5 seconds, a water pressure resistance of 13 kPa on all main surfaces, and an oil repellency of “Yes”.

(Comparative Example 4)
A chemical film was obtained in the same manner as in Example 2 except that the masking layer was not disposed and that the chemical etching time was 23 minutes to obtain a polymer film. Thus, the opening diameter of the through-hole in each main surface of the polymer film obtained was 5.0 micrometers about any main surface.

  Next, the produced polymer film was subjected to a liquid repellent treatment in the same manner as in Example 1. The waterproof breathable membrane thus obtained had an air permeability (Gurley number) of 0.5 seconds, a water pressure resistance of 9 kPa on all main surfaces, and an oil repellency of “Yes”.

  The waterproof breathable membrane of the present invention can be used in various applications for preventing water permeation while ensuring air permeability. There are no particular limitations on devices, equipment, components, structures, etc. to which the waterproof breathable membrane of the present invention can be applied.

DESCRIPTION OF SYMBOLS 1 Waterproofing air-permeable membrane 2 Polymer film 3 Liquid repellent layer 4a, 4b (Main surface of polymer film 2) 5 Through-hole 6 Center axis 7 (through-hole 5 center axis 7) N) Section 8a Opening (through hole 5 in main surface 4a) 8b Opening (through hole 5 in main surface 4b) 9 Breathable support layer 11 Waterproof ventilation member 12 Waterproof ventilation structure 21 Ion 22 Original film 23 (Polymer film) Trajectory of ion 2 collision in 1 31 Sending roll 32 Irradiation roll 33 Ion beam 34 Winding roll 41 Masking layer 51 Support body 81 Housing 82 Opening 83 (in housing 81) Inside 83 (In housing 81)

Claims (18)

It is composed of a polymer film having a through hole extending from one main surface to the other main surface,
The through hole is a straight hole in which the central axis of the through hole extends linearly,
The through hole has a shape in which an area of a cross section perpendicular to a direction in which the central axis extends increases from one main surface to the other main surface of the polymer film,
A waterproof air-permeable membrane, wherein a ratio a / b between an opening diameter a of the through hole in the one main surface and an opening diameter b of the through hole in the other main surface is 80% or less.   2. The waterproof breathable membrane according to claim 1, wherein the through hole has a shape in which an area of the cross section continuously increases from the one main surface to the other main surface.   The waterproof breathable membrane according to claim 1 or 2, wherein the opening diameter a is 12 µm or less. The waterproof breathable membrane according to any one of claims 1 to 3, wherein the density of the through holes in the polymer film is 1 x 10 ³ pieces / cm ² or more and 1 x 10 ⁹ pieces / cm ² or less.   The waterproof breathable membrane according to any one of claims 1 to 4, wherein an opening ratio of the through hole in the one main surface is 50% or less.   The polymer film has the through-hole extending in a direction in which a central axis is inclined with respect to a direction perpendicular to a main surface of the film, and the through-hole having different directions extending in an inclined manner is mixed in the polymer film. The waterproof breathable membrane according to any one of claims 1 to 5.   The waterproof breathable membrane according to any one of claims 1 to 6, which has been subjected to a liquid repellent treatment.   The waterproof breathable membrane according to any one of claims 1 to 7, which has an air permeability of 0.5 seconds or more in the thickness direction, indicated by a Gurley number measured in accordance with JIS L1096.   The waterproof breathable membrane according to any one of claims 1 to 8, wherein the waterproof pressure measured in accordance with JIS L1092 water resistance test B method (high water pressure method) is 5 kPa or more. The water pressure measured in accordance with the provisions of the water resistance test method B (high water pressure method) of JIS L1092, from the water pressure measured from the one main surface side, from the other main surface side The waterproof breathable membrane according to any one of claims 1 to 9, wherein the measured water pressure difference minus the water pressure difference is 5 kPa or more. The polymer film is an alkaline solution, an acidic solution or an oxidizing agent, an alkaline solution or acidic solution by decomposing the resin by adding at least one selected from organic solvents and surfactants of claims 1-10 configured The waterproof breathable membrane according to any one of the above. The waterproof breathable membrane according to any one of claims 1 to 10 , wherein the polymer film is composed of at least one selected from polyethylene terephthalate, polycarbonate, polyimide, polyethylene naphthalate, and polyvinylidene fluoride. The waterproof breathable membrane according to any one of claims 1 to 12 , wherein a coloring treatment for absorbing light contained in a wavelength range of 380 nm to 500 nm is applied. The waterproof breathable membrane according to any one of claims 1 to 12 , which is colored black, gray, brown or pink. The polymer film further comprises a laminated air-permeable support layer, a waterproof breathable film according to any one of claims 1 to 1 4. The waterproof breathable membrane according to any one of claims 1 to 15 ,
A waterproof ventilation member comprising: a support joined to the waterproof ventilation membrane. A housing having an opening;
A waterproof breathable membrane disposed so as to close the opening and preventing water from entering the inside through the opening while allowing gas to pass between the inside and outside of the housing;
A waterproof ventilation structure, wherein the waterproof ventilation film is the waterproof ventilation film according to any one of claims 1 to 15 . The waterproof breathable film, said one main surface of the film is the outer casing, the other principal surface is located in said housing so as to face the inside of the housing, according to claim 1 7 Waterproof ventilation structure as described in.