Porous film, air-permeable member, and member supply sheet

Abstract

A porous film contains a thermoplastic resin not containing fluorine as a main component, and has a breaking strain of 15% or less in a tensile test in an environment at a temperature of 25°C. A gas-permeable member has a porous film and an adhesive layer joined to the porous film. A member supply sheet has a gas-permeable member disposed on a surface of an object having an open-faced surface, and a base sheet having the gas-permeable member disposed on a surface thereof, the gas-permeable member having a porous film having a shape that covers the opening when disposed on the surface, and an adhesive layer joined to the porous film.

Description

Technical Field

[0001] This invention relates to porous membranes, breathable components, and sheet for supplying components. Background Technology

[0002] Porous membranes are used in various applications such as filters, sound-permeable membranes, air-permeable membranes, and diaphragms.

[0003] Previously, porous membranes containing fluorinated resins have been proposed as porous membranes (for example, see Patent Document 1). Porous membranes containing fluorinated resins are, for example, polytetrafluoroethylene (PTFE) porous membranes.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-503991 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Porous membranes are sometimes supplied in the form of a wound body rolled into a roll. When a porous membrane, such as a PTFE porous membrane, has a property of easy stretching, it is stretched when unwound from the roll body, and sometimes its properties change. Therefore, for porous membranes with easy stretching properties, it is necessary to design the product to account for the changes in properties during the manufacturing process.

[0009] Therefore, the object of the present invention is to provide a porous membrane, a breathable component, and a component supply sheet suitable for suppressing changes in properties.

[0010] means for solving problems

[0011] The present invention provides a porous membrane, wherein the porous membrane comprises a fluorine-free thermoplastic resin as the main component, and the tensile strain of the porous membrane is less than 15% in a tensile test at a temperature of 25°C.

[0012] In another aspect, the present invention provides a breathable component having a porous membrane as described above and an adhesive layer bonded to the porous membrane.

[0013] In another aspect, the present invention provides a component supply sheet comprising: a breathable member disposed on the surface of an object having an opening; and a substrate sheet having the breathable member disposed on its surface, wherein the breathable member comprises: a porous membrane having a shape that covers the opening when disposed on the surface; and an adhesive layer bonded to the porous membrane, the porous membrane being the porous membrane of the present invention.

[0014] Invention Effects

[0015] According to the present invention, it is possible to provide fluorine-free porous membranes, breathable components, and component supply sheets suitable for suppressing changes in properties. Attached Figure Description

[0016] Figure 1 A cross-sectional view illustrating an example of the porous membrane of the present invention.

[0017] Figure 2 To indicate the use of measurement Figure 1 A schematic diagram of the T-type peel test method for the cohesiveness of porous membranes.

[0018] Figure 3 To explain Figure 1 A diagram showing how to determine the distance between nodes of a porous membrane.

[0019] Figure 4 A cross-sectional view illustrating an example of the membrane component of the present invention.

[0020] Figure 5 To illustrate Figure 4 A cross-sectional view of a deformed membrane component, Example 1.

[0021] Figure 6 To illustrate Figure 4 A cross-sectional view of a modified example 2 (wound body) of a membrane component.

[0022] Figure 7 A cross-sectional view illustrating an example of the breathable component of the present invention.

[0023] Figure 8 To illustrate Figure 7 A cross-sectional view of a modified example 1 of a breathable component.

[0024] Figure 9 To illustrate Figure 7 A cross-sectional view of a modified example 2 of the ventilated component.

[0025] Figure 10 To illustrate Figure 7 A cross-sectional view of a modified example 3 of the ventilated component.

[0026] Figure 11 To illustrate Figure 7 A cross-sectional view of a modified example 4 of the ventilated component.

[0027] Figure 12 To illustrate Figure 7 A cross-sectional view of a modified example 5 of a breathable component.

[0028] Figure 13A cross-sectional view illustrating an example of the component supply sheet of the present invention.

[0029] Figure 14 To illustrate Figure 13 A cross-sectional view of a modified example 1 of the component supply sheet.

[0030] Figure 15 To illustrate Figure 13 A cross-sectional view of a modified example 2 of the component supply sheet.

[0031] Figure 16A A figure (1000x magnification) showing the results of observing the surface of the porous membrane of Example 1 using a scanning electron microscope (SEM).

[0032] Figure 16B for Figure 16A A magnified view of a portion (2000x).

[0033] Figure 16C A graph (1000x magnification) showing the results of SEM observation of the cross-section of the porous membrane of Example 1.

[0034] Figure 17A A figure (2000x magnification) showing the results of SEM observation of the surface of the porous membrane of Comparative Example 1.

[0035] Figure 17B A graph (1000x magnification) showing the results of SEM observation of the cross-section of the porous membrane of Comparative Example 1.

[0036] Figure 18 A graph showing the change (R1-R2) before and after the heat resistance test of the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 7, which are obtained by dividing the air permeability by the water pressure resistance.

[0037] Figure 19 The SS curves are for the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 4. Detailed Implementation

[0038] The porous membrane of the first embodiment of the present invention comprises a fluorine-free thermoplastic resin as the main component, and the tensile strain of the porous membrane is less than 15% in a tensile test at a temperature of 25°C.

[0039] In a second aspect of the invention, for example, in the porous membrane of the first aspect, no yield point is observed in the stress-strain curve obtained by the tensile test.

[0040] In a third aspect of the invention, for example, in the porous membrane of the first or second aspect, the thermoplastic resin is a polyolefin resin.

[0041] In the fourth aspect of the present invention, for example, the cohesive force of the porous membrane in any of the first to third aspects is 0.1 N / 10 mm or more.

[0042] In the fifth aspect of the present invention, for example, the porous membrane of any of the first to fourth aspects has a water pressure resistance greater than 140 kPa and an air permeability expressed as a Gurley number of less than 50 seconds / 100 mL.

[0043] In the sixth aspect of the present invention, for example, the porous membrane of any one of the first to fifth aspects has multiple nodes and multiple fibrils, wherein the equivalent circle diameter of the nodes is 3.5 μm or more.

[0044] In the seventh aspect of the present invention, for example, in the porous membrane of the sixth aspect, the distance between the nodes is 1.5 μm or more.

[0045] In the eighth aspect of the present invention, for example, in the porous membrane of any of the first to seventh aspects, the equivalent circle diameter of the pores is 0.8 μm or more.

[0046] In the ninth aspect of the present invention, for example, in the porous membrane of any of the fifth to eighth aspects, when the value obtained by dividing the air permeability by the water pressure resistance is defined as ratio R1, and the value obtained by dividing the air permeability of the porous membrane after a heat resistance test at 200°C for 5 minutes by the water pressure resistance is defined as ratio R2, the following condition is satisfied: R1-R2≥-0.015.

[0047] In the tenth aspect of the present invention, for example, in the porous membrane of any of the first to ninth aspects, the porosity is 30% or more when the surface of the porous membrane is observed with a scanning electron microscope.

[0048] In the eleventh aspect of the present invention, for example, the porous membrane of any one of the first to tenth aspects is a stretched membrane.

[0049] The breathable member according to the twelfth aspect of the present invention has, for example, a porous membrane according to any one of the first to eleventh aspects; and an adhesive layer bonded to the porous membrane.

[0050] The thirteenth aspect of the present invention relates to a breathable member, which is a member supply sheet having: a breathable member and a substrate sheet, the breathable member being disposed on the surface of an object having an open surface, the substrate sheet having the breathable member disposed on its surface, wherein the breathable member has: a porous membrane having a shape that covers the opening when disposed on the surface; and an adhesive layer that is bonded to the porous membrane, the porous membrane being, for example, a porous membrane of any of the first to eleventh aspects.

[0051] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

[0052] [Porous membrane]

[0053] An example of the porous membrane of the present invention is shown in Figure 1 middle. Figure 1 The porous membrane 1 contains a fluorine-free thermoplastic resin as its main component. "Main component" refers to the component with the highest content by weight in the porous membrane 1. With this configuration, the porous membrane 1 can, for example, be adhered to objects such as smartphone casings using hot-melt adhesive without the need for an adhesive layer.

[0054] In a tensile test at 25°C, the fracture strain of the porous membrane 1 is less than 15%. A porous membrane 1 that meets the above numerical range is less prone to elongation when unwound from a wound body, and its properties are less likely to change.

[0055] The upper limit of the fracture strain of the porous membrane 1 can be 14% or less. The lower limit of the fracture strain of the porous membrane 1 is, for example, 4% or more. The lower limit of the fracture strain of the porous membrane 1 can be 5% or more. The fracture strain of the porous membrane 1 can be 4% or more and 14% or less.

[0056] In a tensile test at 25°C, the maximum stress of porous membrane 1 can reach 12 N / mm². 2 the following.

[0057] The maximum stress of porous membrane 1 can be up to 11 N / mm. 2 The following can also be 10 N / mm 2 Below. The lower limit of the maximum stress of porous membrane 1 is, for example, 3 N / mm. 2 The lower limit of the maximum stress of porous membrane 1 can be 4 N / mm². 2 The maximum stress of porous membrane 1 can be 3 N / mm. 2 Above and 11N / mm 2 The following can also be 3N / mm 2 Above and 10N / mm 2 the following.

[0058] The fracture strain and maximum stress of the porous membrane 1 can be determined according to JIS K7127:1999, by a tensile test at 25°C as described below. First, the porous membrane 1 is punched using a No. 6 dumbbell-shaped tensile test piece cutter, thus producing a test piece. At 25°C and 50%RH, a tensile test is performed using a tensile testing machine (e.g., an Autograph AGS-X benchtop precision universal testing machine manufactured by Shimadzu Corporation), with a chuck distance of 25 mm and a tensile speed of 50 mm / min, using the No. 6 dumbbell-shaped tensile test piece, and the stress-strain curve (SS curve) is obtained. Based on the SS curve, the tensile stress (maximum stress) and strain (fracture strain) at fracture of the test piece can be determined.

[0059] The porous membrane 1 did not show a yield point in the SS curve obtained by the above tensile test. A porous membrane 1 with such a structure is not easily elongated when unwound from a wound body, and its properties are not easily altered.

[0060] For example, Figure 19 The SS curves are for the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 4, which will be described later. Figure 19 As shown, the porous membranes of Examples 1 to 5 did not show a yield point in the SS curve, and the plastic region and elastic region could not be distinguished.

[0061] like Figure 18 As shown, the porous membrane 1 exhibits monotonically increasing stress-strain behavior in the SS curve obtained by the above tensile test.

[0062] The cohesion of the porous membrane 1 is preferably 0.1 N / 10 mm or higher. A porous membrane 1 with this configuration, for example, suppresses cohesion failure when mounted on a smartphone casing or similar device.

[0063] The upper limit of the cohesion of the porous membrane 1 is, for example, 2.0 N / 10 mm or less. The upper limit of the cohesion of the porous membrane 1 can be 1.0 N / 10 mm or less.

[0064] The cohesion of the porous membrane 1 can be implemented according to JIS Z0237:2009 by the method described below.

[0065] Figure 2This is a schematic diagram illustrating the method for a T-type peel test used to determine the cohesiveness of a porous membrane 1. First, the porous membrane 1 is cut to a size of 100 mm in length and 10 mm in width. Next, two double-sided adhesive tapes 51 (manufactured by Nitto Denko Corporation, No. 5610) with the same shape as the cut porous membrane 1 are prepared. Each double-sided adhesive tape 51 is adhered to one and the other side of the porous membrane 1, respectively, with its outer periphery aligned with both sides. Next, two PET films 52 (25 μm thick), each 150 mm in length and 10 mm in width, are prepared. Each PET film 52 is adhered to one and the other side of the porous membrane 1, respectively, using the double-sided adhesive tapes 51. The PET films 52 are adhered in such a manner that the two ends of each PET film 52 in the width direction are aligned with the two ends of the porous membrane 1 in the width direction, and that the two ends of each PET film 52 in the length direction do not overlap with the porous membrane 1 and the double-sided adhesive tapes 51 when viewed from a direction perpendicular to the main surface of the PET film 52. However, the length (in the length direction) of the free end of each PET film 52 is such that the chuck of the tensile testing machine can stably grip the length of the PET film 52 (e.g., 25 mm). Next, a 2 kg load is applied while the rollers move back and forth once, applying a pressing force in the thickness direction of the laminate 50 of PET film 52 / double-sided adhesive tape 51 / porous film 1 / double-sided adhesive tape 51 / PET film 52. Then, the laminate is cured at room temperature for 24 hours. The cured laminate is used as test piece 50.

[0066] Next, a tensile testing machine (e.g., the Autograph AGS-X benchtop precision universal testing machine manufactured by Shimadzu Corporation) is prepared. The free end of one PET film 52 at one end of the test piece 50 along its length is fixed to the upper chuck 61 of the tensile testing machine. The free end of another PET film 52 at the other end of the test piece 50 along its length is mounted to the lower chuck 62. Then, under the conditions of a test temperature of 25°C and a tensile speed of 300 mm / min, a tensile test is performed by stretching the upper end of one PET film 52 upwards, thereby causing the porous membrane 1 to coagulate and break. After the start of the test, the stress measured between the chucks at the initial 25 mm displacement is ignored, and the average value of the measured stress (N) continuously recorded at the subsequent 50 mm displacement is taken as the cohesive force (N / 10 mm) of the porous membrane 1.

[0067] The water pressure resistance of the porous membrane 1 was evaluated by the water resistance test method B (high water pressure method) specified in JIS L1092:2009, preferably greater than 140 kPa. The porous membrane 1 that meets the above numerical range has high water resistance.

[0068] The lower limit of the water pressure resistance of the porous membrane 1 can be above 150 kPa or above 160 kPa. The upper limit of the water pressure resistance of the porous membrane 1 is, for example, below 2000 kPa. The water pressure resistance of the porous membrane 1 can be above 150 kPa and below 2000 kPa, or above 160 kPa and below 2000 kPa.

[0069] The water pressure resistance of the porous membrane 1 can be measured using a testing fixture, according to the water resistance test method described above, as follows. One example of the testing fixture is a 47mm diameter stainless steel (SUS) circular plate with a centrally located through-hole (having a circular cross-section) and a diameter of 1.0mm. This circular plate has a thickness that will not deform under the applied water pressure during the water pressure resistance test. The water pressure resistance test using this fixture can be performed as follows.

[0070] The porous membrane 1, which is the object of evaluation, is fixed to one side of the measuring fixture by covering the opening of the through hole. The fixing is performed in a manner that prevents water leakage from the fixed portion of the membrane during the water pressure resistance test. The porous membrane 1 can be fixed using double-sided adhesive tape with a perforation (1.6 mm in diameter) punched out at the center, matching the shape of the opening. The double-sided adhesive tape is positioned between the measuring fixture and the porous membrane 1, with the perforation surrounding it aligned with the opening. Next, the measuring fixture with the porous membrane 1 fixed is placed in the test apparatus with the side of the porous membrane 1 opposite to the fixed surface as the water pressure application surface during the test. The water pressure resistance is measured according to Method B (high water pressure method) of water resistance test as specified in JIS L1092:2009. The water pressure resistance is measured based on the water pressure at which water exits from point 1 on the membrane surface of the porous membrane 1. The measured water pressure resistance can be taken as the water pressure resistance of the porous membrane 1. The test apparatus can be a device with the same configuration as the water resistance test apparatus illustrated in JIS L1092:2009, and with a test piece mounting structure capable of setting the aforementioned measuring fixture.

[0071] The thickness-direction air permeability of the porous membrane 1, expressed as a Graeme number, is less than 50 seconds / 100 mL. Therefore, the porous membrane 1 exhibits high air permeability. In this specification, "Graeme number" refers to the air permeability resistance (Graeme permeability) measured according to the Wang Yan test machine method specified in JIS P8117:2009.

[0072] The upper limit of the air permeability of the porous membrane 1, expressed in terms of Graeme number, can be less than 40 seconds / 100 mL, less than 35 seconds / 100 mL, less than 30 seconds / 100 mL, and further less than 25 seconds / 100 mL. The lower limit of the air permeability of the porous membrane 1, expressed in terms of Graeme number, is, for example, greater than 0.1 seconds / 100 mL. The lower limit of the air permeability of the porous membrane 1, expressed in terms of Graeme number, can be greater than 1 second / 100 mL or greater than 5 seconds / 100 mL. The air permeability of the porous membrane 1 can be greater than 0.1 seconds / 100 mL and less than 40 seconds / 100 mL, greater than 0.1 seconds / 100 mL and less than 35 seconds / 100 mL, greater than 0.1 seconds / 100 mL and less than 30 seconds / 100 mL, and further greater than 0.1 seconds / 100 mL and less than 25 seconds / 100 mL.

[0073] It should be noted that even if the size of the porous membrane 1 does not meet the recommended size (50mm×50mm) of the test piece for the Wang Yan test machine method, the air permeability resistance (Gerley air permeability) can still be evaluated based on the Wang Yan test machine method by using a measuring fixture.

[0074] The measuring fixture has a shape and size suitable for mounting on the air permeability measuring section of a pressure testing machine, and is designed with a thickness and material that will not deform due to the pressure difference applied to the test piece during air permeability resistance measurement. An example of the measuring fixture is a SUS circular plate with a thickness of 2 mm and a diameter of 47 mm. A through-hole with an opening smaller than the size of the membrane being evaluated is pre-formed at the center of the surface of the measuring fixture. The cross-section of the through-hole is typically circular, and its diameter is set such that the opening of the through-hole is completely covered by the membrane being evaluated. For example, a diameter of 1 mm or 2 mm can be used for the through-hole. Next, the porous membrane 1 being evaluated is fixed to one surface of the measuring fixture in a manner that covers the opening. The fixing is performed in such a way that, during the air permeability resistance measurement, air only passes through the effective test section of the porous membrane 1 (the portion overlapping the opening when viewed from a direction perpendicular to the main surface of the fixed porous membrane 1), and the fixed portion does not obstruct the passage of air in the effective test section of the porous membrane 1. The porous membrane 1 can be fixed using double-sided adhesive tape with a vent cut out at the center, the shape of which matches the opening. The double-sided adhesive tape is positioned between the measuring fixture and the porous membrane 1, with the vent surrounding it aligned with the opening. Next, the measuring fixture with the porous membrane 1 fixed is placed in the air permeability measuring section of the Wang Yan type testing machine, with the fixed surface of the porous membrane 1 facing downstream of the airflow during measurement. The test is performed using the Wang Yan type testing machine method, and the air permeability resistance indication value t shown on the testing machine is recorded. Then, the formula t can be used... K ={t×(area of ​​the effective test section of porous membrane 1 [cm²])} 2 ]) / 6.452[cm2 The recorded air permeability resistance indicator value t is converted into the 6.452 cm value specified in the Wang Yan-style testing machine method. 2 The effective test area value t K and the obtained conversion value t K The air permeability resistance (Gerley air permeability) of the porous membrane 1 was determined according to the Wang Yan-style testing machine method. It should be noted that the air permeability resistance measured without the use of a measuring fixture for the porous membrane 1 with the recommended test piece size (50mm×50mm) that meets the Wang Yan-style testing machine method was confirmed to be highly consistent with the air permeability resistance measured using a measuring fixture after the porous membrane 1 was made into a small piece. That is, the use of the measuring fixture has no substantial effect on the measured value of the air permeability resistance.

[0075] The ratio R1 is defined as the value obtained by dividing the air permeability (seconds / 100mL) of the porous membrane 1 by the water resistance (kPa). The ratio R1 tends to be smaller when the air permeability and water resistance of the porous membrane 1 are both higher. Therefore, the ratio R1 can serve as an indicator for comprehensively evaluating the air permeability and water resistance of the porous membrane 1. The ratio R1 is preferably 0.2 or less, more preferably 0.15 or less. A porous membrane 1 that meets the above numerical range can exhibit excellent air permeability and water resistance. The lower limit of the ratio R1 is, for example, 0.01 or more.

[0076] The air permeability (seconds / 100mL) of the porous membrane 1 after a heat resistance test at 200°C for 5 minutes, divided by the water pressure resistance (kPa), is defined as the ratio R2. The higher the heat resistance of the porous membrane 1, the smaller the difference between ratio R1 and ratio R2. Therefore, the change in the air permeability (seconds / 100mL) divided by the water pressure resistance (kPa) before and after the heat resistance test (R1-R2) can be used as an indicator to evaluate the heat resistance of the porous membrane 1. The porous membrane 1 preferably satisfies the following formula.

[0077] R1-R2≥-0.015

[0078] The porous membrane 1 that meets the above numerical range has high heat resistance.

[0079] The porous membrane 1 can satisfy R1-R2≥-0.014, R1-R2≥-0.012, and R1-R2≥-0.010.

[0080] As described above, the porous membrane 1 contains a fluorine-free thermoplastic resin as its main component. The fluorine-free thermoplastic resin can be a polyolefin resin. By using a polyolefin resin as the thermoplastic resin, it is easy to obtain a porous membrane 1 that is suitable for both water resistance and air permeability.

[0081] Polyolefin resins include polyethylene (PE) resin, polypropylene (PP) resin, and polymethylpentene (PMP) resin.

[0082] Polyolefin resins can be polymethylpentene resins. Polymethylpentene resins refer to homopolymers or copolymers of poly(4-methyl-1-pentene) resins, poly(3-methyl-1-pentene) resins, etc. As copolymers, there are random copolymers and block copolymers, etc. From the viewpoint of heat resistance and processability, homopolymers of poly(4-methyl-1-pentene) resins are preferred.

[0083] Polyolefin resins can be poly(4-methyl-1-pentene) resins. Poly(4-methyl-1-pentene) resins refer to homopolymers of 4-methyl-1-pentene, or copolymers of 4-methyl-1-pentene with at least one α-olefin. The ratio of 4-methyl-1-pentene to α-olefin in the copolymer can be adjusted within a range above 180°C.

[0084] The fluorine-free thermoplastic resin can be a thermoplastic resin with a melting point above 180°C and below 300°C. When the melting point of the thermoplastic resin is above 180°C, sufficient heat resistance can be ensured in the porous membrane 1. When the melting point of the thermoplastic resin is below 300°C, the porous membrane 1 can be produced, for example, by melt molding.

[0085] The melting point of thermoplastic resins can be above 200°C and below 280°C, and more specifically, above 220°C and below 260°C.

[0086] The porous membrane 1 is in the form of a membrane or sheet. The thickness of the porous membrane 1 can be greater than 20 μm and less than 100 μm. When the thickness is within the above-mentioned range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned range.

[0087] The thickness of the porous membrane 1 can be determined, for example, by measuring the thickness at any 5 points on the porous membrane 1 using a dial indicator and averaging these measurements. Alternatively, the thickness of the porous membrane 1 can be measured at any 5 points in a cross-sectional SEM image of the porous membrane 1 and averaged as the result.

[0088] The thickness of the porous membrane 1 can be up to 90 μm or 80 μm.

[0089] The porous membrane 1 may have multiple nodes and multiple fibrils. The porous membrane 1 may have a tortoise-shell structure formed by multiple nodes and multiple fibrils. The aforementioned tortoise-shell structure may exist throughout the porous membrane 1. A porous membrane 1 with such a structure is suitable for suppressing changes in properties. The aforementioned tortoise-shell structure can be confirmed, for example, by observing the main surface of the porous membrane 1 from a vertical direction using a scanning electron microscope (SEM). In this disclosure, "main surface" refers to the surface with the largest area of ​​the membrane or sheet-like component. It should be noted that in this disclosure, the terms "main surface," "surface," and "surface" for the porous membrane 1 are used with the same meaning.

[0090] In this disclosure, "a tortoise-shell-like structure formed by multiple nodes and multiple fibrils" refers to a structure that can be confirmed by observing the surface of the porous membrane 1 using SEM. It is a structure in which island-like regions formed by multiple nodes are irregularly connected, and these island-like regions are interconnected by multiple fibrils. The island-like regions may, for example, have a polygonal shape. It should be noted that the shape of the polygonal region does not necessarily have to be composed only of straight lines; it also includes roughly polygonal regions with some edges that are curved, such as arcs. Furthermore, the polygonal shape is not limited to a hexagonal shape.

[0091] The size of the island regions can vary widely. When the surface of the porous membrane 1 is observed using SEM, island regions of different sizes can exist in random locations. The number of nodes forming relatively large island regions is greater than the number of nodes forming relatively small island regions.

[0092] For example, Figure 16A A figure (1000x magnification) showing the results of SEM observation of the surface of the porous membrane of Example 1 described later. Figure 16B for Figure 16A A magnified view of a portion (2000x). For example... Figure 16A and Figure 16B As shown, the surface of the porous membrane in Example 1 has a tortoise-shell-like structure formed by multiple nodes and multiple fibrils, and island-like regions of different sizes formed by multiple nodes exist at random locations.

[0093] When observing the cross-section of the porous membrane 1 using SEM, multiple nodes can be observed along the thickness direction. These multiple nodes can exist throughout the entire thickness direction of the porous membrane 1. They can also exist uniformly along the thickness direction of the porous membrane 1. Adjacent block nodes can be connected to each other via multiple fibrils, or they can be directly connected without multiple fibrils.

[0094] Regarding the thickness direction of the porous membrane 1, it is preferable to have a large number of connection points between nodes or between block nodes. When there are many connection points between nodes or between block nodes, the gaps (pores) formed between them tend to accumulate. With such a cross-sectional structure, the pore diameter tends to increase, thus making it easier to achieve the air permeability within the aforementioned numerical range.

[0095] For example, Figure 16C A graph (1000x magnification) showing the results of SEM observation of the cross-section of the porous membrane of Example 1 described later. Figure 16C As shown, when observing the cross-section of the porous membrane in Example 1, there are many connection points between the block nodes, resulting in the accumulation of gaps (pores).

[0096] When the surface of the porous membrane 1 is observed using SEM, the equivalent circle diameter of the nodes of the porous membrane 1 is preferably 3.5 μm or more. When the equivalent circle diameter of the nodes is within the above-mentioned range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned range. It should be noted that in this disclosure, the terms "equivalent circle diameter of the node," "maximum diameter of the node," and "distance between nodes" are used with the same meaning for both "node" and "island-like region formed by multiple nodes."

[0097] The lower limit of the equivalent circle diameter of the nodes of the porous membrane 1 can be 4.0 μm or more. The upper limit of the equivalent circle diameter of the nodes of the porous membrane 1 is, for example, 12.0 μm or less. The upper limit of the equivalent circle diameter of the nodes of the porous membrane 1 can be 11.0 μm or less, 10.0 μm or less, 9.0 μm or less, and further, 8.0 μm or less. The equivalent circle diameter of the nodes of the porous membrane 1 can be 4.0 μm or more and 12.0 μm or less.

[0098] When observing the surface of the porous membrane 1 using SEM, the maximum diameter of the nodes in the porous membrane 1 is preferably greater than 4.5 μm. When the maximum diameter of the nodes is within the above-mentioned range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned range.

[0099] The lower limit of the maximum diameter of the nodes of the porous membrane 1 can be 4.6 μm or more, 5.0 μm or more, 5.5 μm or more, and further 6.0 μm or more. The upper limit of the maximum diameter of the nodes of the porous membrane 1 is, for example, 15.0 μm or less. The upper limit of the maximum diameter of the nodes of the porous membrane 1 can be 14.0 μm or less, 13.0 μm or less, and further 12.0 μm or less. The maximum diameter of the nodes of the porous membrane 1 can be 4.6 μm or more and 15.0 μm or less, 5.0 μm or more and 15.0 μm or less, 5.5 μm or more and 15.0 μm or less, and further 6.0 μm or more and 15.0 μm or less.

[0100] The maximum diameter of the nodes and the equivalent circle diameter of the nodes of porous membrane 1 can be determined by the method described below. First, the surface of porous membrane 1 is observed using SEM (e.g., referring to...). Figure 16A Next, the SEM observation image (or a portion thereof) obtained using image analysis software is binarized. Nodes are identified from the obtained binarized image, and the area of ​​each node in the image is calculated. For each node, the equivalent circle diameter is calculated based on the calculated area. The equivalent circle diameter is the diameter of a circle with an area equal to the area of ​​the node being measured. The average value of the calculated equivalent circle diameters can be considered as the equivalent circle diameter of the nodes of porous membrane 1. Next, a histogram is created based on the number of nodes classified by equivalent circle diameter, thereby obtaining the equivalent circle diameter distribution (number basis). The number of nodes used as the calculation basis for the equivalent circle diameter distribution is obtained by counting the number of nodes present in the aforementioned image. In the obtained equivalent circle diameter distribution, the particle size corresponding to the cumulative volume reaching 100% from the side with the smallest particle size is considered as the maximum particle size of the nodes of porous membrane 1. The equivalent circle diameter and the maximum diameter are determined by measuring 30 or more nodes, for example, 50 to 200 nodes. It should be noted that when identifying nodes, nodes located at the image edges are omitted from the analysis. ImageJ can be used as an image analysis software for example.

[0101] When observing the surface of the porous membrane 1 using SEM, the distance between the nodes of the porous membrane 1 is preferably 1.5 μm or more. When the distance between the nodes is within the above-mentioned range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned range.

[0102] The lower limit of the distance between nodes of porous membrane 1 can be 1.6 μm or more, or 1.7 μm or more. The upper limit of the distance between nodes of porous membrane 1 is, for example, 8.0 μm or less. The upper limit of the distance between nodes of porous membrane 1 can be 7.0 μm or less, 6.0 μm or less, or 5.0 μm or less. The distance between nodes of porous membrane 1 can be 1.6 μm or more and 8.0 μm or less, or 1.7 μm or more and 8.0 μm or less.

[0103] The distance between nodes of porous membrane 1 can be determined by the method described below. Figure 3 For illustrative purposes Figure 1 A schematic diagram illustrating the method for determining the distance between nodes of porous membrane 1. First, a binarized image is obtained using the same method as explained for the equivalent circle diameter and maximum diameter of the nodes of porous membrane 1, and the nodes are identified from the binarized image (refer to...). Figure 3 ).like Figure 3 As shown, the distance L between node A and node B is... AB The distance can be calculated by subtracting half the equivalent circle diameter of node A and half the equivalent circle diameter of node B from the distance between the centroid c of node A and the centroid c of node B. In this way, the distance between the nodes (L) can be calculated for the three closest nodes (node ​​B, node C, and node D) to node A. AB L AC and L AD That is, the node distance (L) to the fourth or subsequent node (node ​​E) from node A is not used. AE In this process, nodes (nodes F) that overlap with node A in the image are excluded from the three nodes that are closest to node A (first to third closest). The average distance between node A and the three nodes closest to node A, calculated in this way, is taken as the distance between nodes of node A. The distances between nodes are calculated similarly for all nodes in the image. The average of the calculated distances between nodes can be taken as the distance between nodes of porous membrane 1.

[0104] As described above, the porous membrane 1 has multiple gaps (pores). When the surface of the porous membrane 1 is observed using SEM, the equivalent circle diameter of the pores in the porous membrane 1 is preferably 0.8 μm or more. When the equivalent circle diameter of the pores meets the above-mentioned numerical range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned numerical range.

[0105] The lower limit of the equivalent circle diameter of the pores in the porous membrane 1 can be 1.0 μm or more, or 1.5 μm or more. The upper limit of the equivalent circle diameter of the pores in the porous membrane 1 is, for example, 5.0 μm or less. The upper limit of the equivalent circle diameter of the pores in the porous membrane 1 can be 4.0 μm or less, or 3.0 μm or less. The equivalent circle diameter of the pores in the porous membrane 1 can be 1.0 μm or more and 5.0 μm or less, or 1.5 μm or more and 5.0 μm or less.

[0106] When observing the surface of the porous membrane 1 using SEM, the maximum diameter of the pores in the porous membrane 1 is preferably 1.4 μm or more. When the maximum pore diameter meets the above-mentioned numerical range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned numerical range.

[0107] The lower limit of the maximum pore diameter of the porous membrane 1 can be 1.5 μm or more, or 2.0 μm or more. The upper limit of the maximum pore diameter of the porous membrane 1 is, for example, 7.0 μm or less. The upper limit of the maximum pore diameter of the porous membrane 1 can be 6.0 μm or less, or 5.0 μm or less. The maximum pore diameter of the porous membrane 1 can be 1.5 μm or more and 7.0 μm or less, or 2.0 μm or more and 7.0 μm or less.

[0108] The equivalent circle diameter and maximum diameter of the pores in the porous membrane 1 can be obtained using the same method as described above for determining the equivalent circle diameter and maximum diameter of the nodes in the porous membrane 1. Specifically, the pores are identified from the obtained binary image. It should be noted that pores located at the image edges are omitted from the analysis when identifying pores.

[0109] When the surface of the porous membrane 1 is observed using SEM, the porosity of the porous membrane 1 is preferably 30% or higher. When the porosity meets the above-mentioned value range, it is easy to achieve water pressure resistance and air permeability that meet the above-mentioned value range.

[0110] The lower limit of the porosity of porous membrane 1 can be above 32%, above 35%, or above 40%. The upper limit of the porosity of porous membrane 1 is, for example, below 95%. The upper limit of the porosity of porous membrane 1 can be below 90%. The porosity of porous membrane 1 can be above 32% and below 95%, above 35% and below 95%, or above 40% and below 95%.

[0111] The porosity of the porous membrane 1 can be determined using the same method as described above for determining the maximum diameter of the nodes and the equivalent circle diameter of the nodes in the porous membrane 1. Specifically, pores are identified from the obtained binarized image, and the area of ​​each pore in the image is calculated. By calculating the ratio of the total area of ​​the pores to the area of ​​the image, the porosity of the porous membrane 1 can be determined. The porosity is determined by measuring 30 or more pores, for example, 50 to 200 pores.

[0112] The porous membrane 1 can be a stretched membrane. When the porous membrane 1 is a stretched membrane, it is easy to control water pressure resistance and air permeability. The stretched membrane can be a biaxial stretched membrane or a uniaxial stretched membrane.

[0113] At least one main surface of the porous membrane 1 can be subjected to a surface modification treatment. Examples of surface modification treatments include: oil-repellent treatment, chemical treatment, sputtering etching treatment, plasma treatment, etc. In the area where the surface modification treatment has been performed, the adhesion of the porous membrane 1 is improved.

[0114] Liquid-repellent treatment can be applied to at least one main surface of the porous membrane 1. The liquid-repellent treatment is typically performed by coating the surface of the porous membrane 1 with a liquid-repellent agent or by immersing the porous membrane 1 in a liquid-repellent agent. There are no particular limitations on the liquid-repellent agent; it can be a fluorinated liquid-repellent agent, an organosilicon liquid-repellent agent, or an acrylic liquid-repellent agent. Fluorinated liquid-repellent agents, for example, have a structure with a fluorine-saturated hydrocarbon side chain (perfluoroalkyl) on the main chain of an acrylic resin.

[0115] [Methods for manufacturing porous membranes]

[0116] The porous membrane 1 described above can be manufactured, for example, by the following method.

[0117] The method for manufacturing the porous membrane 1 includes, for example,: mixing a composition comprising a fluorine-free thermoplastic resin and a plasticizer to obtain a compound (step S1); pressing the compound to obtain a pressed body (step S2); cooling the pressed body to obtain a molded body (step S3); annealing the molded body (step S4); stretching the annealed molded body to obtain a sheet (step S5); and extracting the plasticizer from the sheet (step S6).

[0118] Alternatively, as another method, the manufacturing method of the porous membrane 1 includes, for example,: mixing a composition comprising a fluorine-free thermoplastic resin and a plasticizer to obtain a compound (step S1); extruding the compound using a twin-screw extruder (step ST2); cooling the extruded compound to obtain a molded body (step ST3); annealing the molded body (step S4); stretching the annealed molded body to obtain a sheet (step S5); and extracting the plasticizer from the sheet (step S6).

[0119] Steps S1 to S4 correspond to the process of producing the precursor of the porous membrane 1. Steps S5 to S6 correspond to the process of growing the porous structure. It should be noted that the manufacturing method may also include cooling the molded body obtained by pressing the compound on a metal plate to obtain a molded body, or cooling the compound with a metal roller to obtain a molded body (step S3') instead of step S3.

[0120] Step S1 is performed, for example, at a temperature of 230°C to 260°C for 5 to 30 minutes.

[0121] As a fluorine-free thermoplastic resin, polymethylpentene resin can be used, for example.

[0122] In the composition comprising a thermoplastic resin and a plasticizer, resins such as polyethylene, polypropylene, poly-1-butene, and cyclic polyolefins may be mixed within a range that does not affect the properties of the porous membrane 1.

[0123] Plasticizers are non-volatile solvents that, when mixed with thermoplastic resins such as polymethylpentene, form a mixture at a temperature above the resin's melting point and exhibit thermally induced phase separation upon cooling. Plasticizers can be liquid or solid at room temperature. They can be used alone or in combination with other plasticizers.

[0124] The mixing ratio of thermoplastic resin and plasticizer is set in a manner that allows for the formation of a uniform compound in step S1 and the formation of a molded article in step S3 (or steps S2-3). Specifically, the weight ratio of thermoplastic resin in the composition comprising thermoplastic resin and plasticizer is, for example, 20% by weight or more and 80% by weight or less, preferably 30% by weight or more and 70% by weight or less. By having a weight ratio of thermoplastic resin of 20% by weight or more, excessive reduction in the viscosity of the composition can be avoided. By having a weight ratio of thermoplastic resin of 80% by weight or less, a good porous structure is easily obtained.

[0125] In a composition containing a thermoplastic resin and a plasticizer, additives such as antioxidants, nucleating agents, antistatic agents, flame retardants, lubricants, UV absorbers, colorants, and inorganic fillers for improving strength may be further mixed in, depending on the purpose.

[0126] Step S2 is performed, for example, at a temperature of 230°C to 260°C for 2 to 30 minutes. The thickness of the pressed body obtained by step S2 is, for example, 0.1 mm.

[0127] In step S3, for example, the pressed body obtained in step S2 is brought into contact with a heat conductor and cooled to a temperature sufficiently low than the crystallization temperature of the thermoplastic resin to cure it. Examples of heat conductors used for cooling include water, air, metal, and plasticizers.

[0128] The manufacturing method may also include extruding the compound using a twin-screw extruder (step ST2) instead of step S2. In step ST2, the compound can be extruded onto metal rollers with controlled surface temperature. A flat die (coat hanger die) can be used in the extrusion of the compound. By using a flat die, the compound can be extruded in a wide width, thus easily obtaining a sheet-like formed body in step ST2.

[0129] In the case where step ST2 replaces step S2, the manufacturing method may also include cooling the extruded compound to obtain a shaped body (step ST3) instead of step S3. In step ST3, for example, a metal roller with a controlled surface temperature can be used to stretch the compound while cooling it, thereby obtaining a sheet-like shaped body. The surface temperature of the metal roller is controlled, for example, at 120°C. There can be multiple metal rollers. By passing the compound through multiple metal rollers, a sheet-like shaped body can be formed while cooling is being performed.

[0130] Step S4 is performed, for example, at a temperature of 180°C to 200°C for 30 to 60 minutes. In step S4, by performing annealing at a temperature near the crystallization peak temperature of the fluorine-free thermoplastic resin (e.g., polymethylpentene resin), the portions that can become highly crystalline nodes and the portions that can become low-crystallinity fibrils tend to aggregate. Therefore, during the stretching in the subsequent step S5, large island-like regions are easily formed, and the distance between these island-like regions tends to increase.

[0131] In step S5, the annealed molded body is stretched at least once in at least one uniaxial direction. Stretching in at least one uniaxial direction includes longitudinal uniaxial stretching, transverse uniaxial stretching, simultaneous biaxial stretching, and successive biaxial stretching. The molded body can be subjected to successive biaxial stretching or simultaneous biaxial stretching. Through step S5, pores are generated in the molded body, and a structure is formed where island-like regions of different sizes, formed by multiple nodes, exist at random locations.

[0132] The stretching temperature can be 20℃~240℃, 50℃~230℃, or 100℃~220℃ for longitudinal and transverse stretching, respectively.

[0133] The stretch ratio, measured in the longitudinal and / or transverse uniaxial direction, can be 2.0 to 10.0 times, 2.0 to 8.0 times, or 2.0 to 5.0 times.

[0134] The strain rate during tension can be 1% / second to 10% / second, 1% / second to 8% / second, or 1% / second to 5% / second in the longitudinal and / or transverse directions. When the strain rate is within the above range, fracture is less likely to occur during tension, thus improving productivity.

[0135] In step S6, for example, an extraction solvent is used to extract and remove the plasticizer from the sheet. After step S6, the sheet after plasticizer removal can be dried using a dryer or by natural drying. The porous membrane 1 can be obtained through the above operations.

[0136] As the extraction solvent, it is preferable to use a solvent that is a poor solvent for thermoplastic resins such as polymethylpentene resin, but a good solvent for plasticizers, and whose boiling point is lower than the melting point of porous membrane 1. Examples of such extraction solvents include: hydrocarbons such as n-hexane and cyclohexane; halogenated hydrocarbons such as dichloromethane and 1,1,1-trichloroethane; alcohols such as ethanol and isopropanol; ethers such as diethyl ether and tetrahydrofuran; and ketones such as acetone and 2-butanone. When safety is a consideration, alcohols and ketones are preferred. Methyl ethyl ketone (MEK) can be used as an extraction solvent.

[0137] Between steps S5 and S6, heat curing can be performed on the sheet. Heat curing can be performed, for example, using a hot air circulating oven. By performing heat curing, the thermal shrinkage of the stretched sheet can be reduced. The heat curing temperature is, for example, 50°C to 240°C. The heat curing temperature can also be 100°C to 230°C, or even 150°C to 220°C.

[0138] Heat setting can be performed after step S5, between steps S5 and S6, or both after steps S5 and S6. Examples of heat setting methods include: using a tenter frame to fix the width direction and continuously passing the product through the heat treatment furnace; applying appropriate tension and continuously passing the product through the heat treatment furnace without fixing the width direction; and winding the product into a roll and feeding it into the heat treatment furnace in batches.

[0139] [Membrane Components]

[0140] An example of the membrane component of the present invention is shown in Figure 4 middle. Figure 4 The membrane component 2 (2A) has a porous membrane 1. Figure 5 The middle shows Figure 4 Example 1: Deformation of a membrane component. Figure 5 The membrane component 2 (2B) also has a breathable support material 3. The breathable support material 3 is laminated on the porous membrane 1. The breathable support material 3 improves the strength and operability (operability) of the membrane component 2.

[0141] The breathable support material 3 typically has higher air permeability in the thickness direction compared to the porous membrane 1. Examples of the breathable support material 3 are woven fabrics, nonwoven fabrics, meshes, and openwork. Examples of materials constituting the breathable support material 3 are polyesters such as polyethylene terephthalate (PET), polyolefins such as polyethylene (PE) and polypropylene (PP), and aromatic polyamide resins. When viewed from a direction perpendicular to the main surface of the membrane member 2, the shape of the breathable support material 3 may be the same as or different from that of the porous membrane 1. When viewed from a direction perpendicular to the main surface of the membrane member 2, the breathable support material 3 may have a peripheral portion corresponding to the peripheral portion of the porous membrane 1.

[0142] Figure 5 The membrane component 2B has a breathable support material 3 disposed on one side of the porous membrane 1. The membrane component 2 may have two or more breathable support materials 3. In the membrane component 2, breathable support materials 3 may be disposed on two sides of the porous membrane 1. The porous membrane 1 and the breathable support materials 3 may be joined by welding such as thermal fusion and ultrasonic welding, or by adhesives or bonding agents.

[0143] The membrane component 2 may also have optional layers and / or components other than those described above.

[0144] The thickness of membrane component 2 is, for example, 1 μm to 300 μm. The thickness of membrane component 2 can also be 50 μm to 200 μm.

[0145] The basis weight of membrane component 2 is, for example, 1.0 g / m³. 2 ~200.0g / m 2 The basis weight of membrane component 2 can be 10.0 g / m³. 2 ~100.0g / m 2 .

[0146] The membrane component 2 may have the same properties as the porous membrane 1, such as air permeability in the thickness direction and / or water pressure resistance.

[0147] Liquid-repellent treatment and / or coloring treatment can also be applied to membrane component 2.

[0148] Membrane component 2 can be used, for example, as a filter component. However, the uses of membrane component 2 are not limited to the examples described above.

[0149] When viewed from a direction perpendicular to the main surface of membrane member 2, the shape of membrane member 2 can be, for example, a polygon including squares and rectangles, a circle, an ellipse, or a strip. The corners of the polygon can be rounded. However, the shape of membrane member 2 is not limited to the above examples. The strip-shaped membrane member 2 can also be wound to form a wound body. In addition, if necessary, it can be wound in a state of being stacked with a release liner.

[0150] Figure 6The middle shows Figure 4 Example 2 of the deformation of the membrane component (wound body). Figure 6 The coil 10 shown includes Figure 4 The membrane component 2A and the release liner 11 are bonded together by an adhesive layer 12. In the winding body 10, the release surface 13 formed when the release liner 11 is peeled off from the membrane component 2A is located between the membrane component 2A and the adhesive layer 12. That is, in the winding body 10, the adhesive layer 12 is peeled off from the membrane component 2A when the release liner 11 is peeled off, thereby obtaining a membrane component 2A without an adhesive layer 12 formed on its surface.

[0151] The membrane member 2A, supplied by the winding body 10 and without an adhesive layer 12 formed on its surface, can be joined to the opening of the housing by any joining method. That is, the membrane member 2A has a high degree of freedom in the joining method with the opening of the housing. Joining methods include, for example, joining by a newly configured adhesive layer on the surface of the membrane member 2A, joining by thermal fusion, and joining by ultrasonic fusion.

[0152] The membrane component 2A supplied by the winding body 10 can be processed into any shape as needed. That is, the membrane component 2A has a high degree of freedom in shape. Here, "shape" includes "size". The above points mean that, according to the winding body 10, the membrane component 2A, which functions as a waterproof membrane, can be supplied in a state with a high degree of freedom in the method of joining with the opening of the shell and / or in shape.

[0153] Furthermore, according to the winding body 10, the misalignment between the film member 2A and the release liner 11 during winding is suppressed by the adhesive layer 12. In the winding body 10, the occurrence of faults (abnormal shape of the winding body) caused by winding tightness, etc., can be suppressed.

[0154] [Breathable components]

[0155] Figure 7 An example of the breathable component of the present invention is shown in the figure. Figure 7 The breathable member 4 (4A) has the porous membrane 1 or membrane member 2 described above as a member that has air permeability in the thickness direction and prevents foreign objects from passing through in that direction. The breathable member 4 is, for example, disposed on the surface of an object having an opening, ensuring air permeability through the opening while preventing foreign objects from passing through it. In this case, the breathable member 4 is typically disposed such that the porous membrane 1 or membrane member 2 covers the opening of the object. Figure 7 The breathable member 4A has a porous membrane 1. Hereinafter, the case in which the breathable member 4 has a porous membrane 1 as a member that has breathability in the thickness direction and prevents foreign objects from passing through in that direction will be described as an example.

[0156] The breathable member 4 (4A) has an adhesive layer 5 disposed on one side of the porous membrane 1. The porous membrane 1 and the adhesive layer 5 are directly bonded. The breathable member 4A can be disposed on the aforementioned surface of the object via the adhesive layer 5.

[0157] Examples of adhesives constituting adhesive layer 5 include acrylic adhesives, silicone adhesives, urethane adhesives, epoxy adhesives, and rubber adhesives. When considering the use of the breathable component 4 at high temperatures, acrylic or silicone adhesives with excellent heat resistance, especially silicone adhesives, are preferred. Adhesive layer 5 can be a substrate-free double-sided adhesive tape. The adhesive can also be a curable adhesive such as phenolic resin, epoxy resin, urea-formaldehyde resin, polyurethane resin, melamine resin, and polyester resin.

[0158] When viewed from a direction perpendicular to the main surface of the porous membrane 1, the outer periphery of the porous membrane 1 coincides with the outer periphery of the adhesive layer 5. Furthermore, when viewed from a direction perpendicular to the main surface of the porous membrane 1, the shape of the adhesive layer 5 corresponds to the shape of the peripheral portion of the porous membrane 1. The area in the porous membrane 1 that is not bonded to the adhesive layer 5 can be considered as the air-permeable area of ​​the air-permeable member 4A. However, the shape of the adhesive layer 5 is not limited to the example described above.

[0159] The area of ​​the breathable zone is, for example, 40mm. 2 The following describes a breathable component 4 whose breathable area falls within this range, for example, suitable for placement on objects with openings of small diameter. The lower limit of the breathable area is, for example, 0.008 mm². 2 That's all. However, the area of ​​the ventilated region can also be larger depending on the type of object to which the ventilated component 4 is to be installed.

[0160] Figure 8 The middle shows Figure 7 Example 1: Deformation of the breathable component. Figure 8 In addition to having an adhesive layer 5 (5B) disposed on the other side of the porous membrane 1, the breathable component 4 (4B) also has a connection with... Figure 7 The porous membrane 1 has the same structure as the breathable component 4A. The porous membrane 1 is sandwiched between a pair of adhesive layers 5 (5A, 5B).

[0161] like Figure 8 As shown, the adhesive layer 5 may include a first adhesive layer 5A bonded to one side (first main surface 1a) of the porous membrane 1 and a second adhesive layer 5B bonded to the other side (second main surface 1b) of the porous membrane 1.

[0162] Figure 9 The middle shows Figure 7 Example 2: Deformation of the breathable component. Figure 9The breathable member 4 (4C) not only has a substrate layer 6 disposed on one side of the porous membrane 1, and the porous membrane 1 and the adhesive layer 5 are bonded through the substrate layer 6, but also has the following characteristics: Figure 7 The structure is the same as that of the breathable component 4A. The strength and operability of the breathable component 4 can be improved by the substrate layer 6, and the damage of the porous membrane 1 during operation or when placed on an object can be suppressed.

[0163] Examples of materials constituting the substrate layer 6 include polyolefins such as PE and PP, polyesters such as PET, silicone resins, polycarbonate, polyimide, polyamide-imide, polyphenylene sulfide, polyether ether ketone (PEEK), polyvinyl chloride, fluorinated resins, and metals such as aluminum and stainless steel. Examples of fluorinated resins include PTFE, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE). However, the materials constituting the substrate layer 6 are not limited to the examples mentioned above.

[0164] When viewed from a direction perpendicular to the main surface of the porous membrane 1, the outer periphery of the porous membrane 1 coincides with the outer periphery of the substrate layer 6. Furthermore, when viewed from a direction perpendicular to the main surface of the porous membrane 1, the shape of the substrate layer 6 corresponds to the shape of the peripheral portion of the porous membrane 1. The area in the porous membrane 1 that is not bonded to the substrate layer 6 can be considered as the air-permeable area of ​​the air-permeable member 4C. However, the shape of the substrate layer 6 is not limited to the example described above.

[0165] The porous membrane 1 and the substrate layer 6 can be bonded by adhesives or glues, or by welding such as thermal fusion and ultrasonic welding. The porous membrane 1 and the substrate layer 6 can also be bonded by an adhesive layer. This adhesive layer can have the same structure as adhesive layer 5. The substrate layer 6 can be a single-sided or double-sided adhesive tape.

[0166] Figure 10 The middle shows Figure 7 Example 3: Deformation of the breathable component. Figure 10 In addition to having a substrate layer 6 (6B) disposed on the other side of the porous membrane 1, the breathable component 4 (4D) also has a similar structure to... Figure 9 The porous membrane 1 has the same structure as the breathable component 4C. The porous membrane 1 is sandwiched between a pair of substrate layers 6 (6A, 6B). This clamping structure further improves the strength and operability of the breathable component 4.

[0167] like Figure 10 As shown, the substrate layer 6 may include a first substrate layer 6A bonded to one side (first main surface 1a) of the porous membrane 1, and a second substrate layer 6B bonded to the other side (second main surface 1b) of the porous membrane 1.

[0168] Figure 11 The middle shows Figure 7Example 4: Deformation of the breathable component. Figure 11 The breathable component 4 (4E) also has a release liner 7, and the porous membrane 1 is bonded to the release liner 7 by an adhesive layer 5 (5B), in addition having a... Figure 8 The breathable component 4B has the same structure.

[0169] like Figure 11 As shown, the breathable member 4 (4E) may also have a release liner 7, with a second adhesive layer 5B disposed between the release liner 7 and the porous membrane 1, and the second adhesive layer 5B bonded to the release liner 7.

[0170] When viewed from a direction perpendicular to the main surface of the porous membrane 1, the release liner 7 has tabs that protrude further outward than the outer periphery of the porous membrane 1. By grasping the tabs, the air-permeable member 4E can be manipulated or placed onto the surface of an object. The release liner 7 is typically removed when using the air-permeable member 4E. The release liner 7 can, for example, be made of the same material as the material constituting the substrate layer 6.

[0171] Figure 12 The middle shows Figure 7 Example 5: Deformation of the breathable component. Figure 12 The breathable member 4 (4F) not only has a release liner 7, but also has a bonding layer 5 (5B) that bonds the substrate layer 6 (6B) to the release liner 7, in addition to having a release liner 7. Figure 10 The breathable components have the same 4D structure.

[0172] [Component supply sheet]

[0173] The breathable component 4 can be supplied, for example, by means of a component supply sheet. Figure 13 The image shows an example of a component supply sheet used as a method for supplying the ventilating component 4. Figure 13 The component supply sheet 20 (20A) includes: a breathable member 4 (4A) disposed on the surface of an object having an opening, and a substrate sheet 9 on which the breathable member 4 (4A) is disposed. The component supply sheet 20A has the breathable member 4A as the breathable member 4. The breathable member 4A includes: a porous membrane 1 having a shape that covers the opening when disposed on the surface of the object, and an adhesive layer 5 bonded to the porous membrane 1.

[0174] The breathable component 4 (4A) is disposed on the substrate sheet 9 via the adhesive layer 5. According to the component supply sheet 20 (20A), for example, the breathable component 4 can be efficiently supplied to the process of disposing of the breathable component 4 on the surface of the object.

[0175] The breathable member 4 can be disposed on the substrate sheet 9 via an adhesive layer on the disposed surface of the breathable member 4 disposed in the substrate sheet 9. The adhesive layer on the disposed surface is preferably weakly adhesive.

[0176] Although the illustration is omitted, multiple breathable components 4 can also be configured on the surface of the substrate sheet 9.

[0177] Examples of materials constituting the substrate sheet 9 include paper, metal, resin, and composites thereof. Metals include, for example, stainless steel and aluminum. Resins include, for example, polyesters such as PET, and polyolefins such as PE and PP. However, the materials constituting the substrate sheet 9 are not limited to the examples mentioned above. The substrate sheet 9 can be in the form of a single sheet or a strip. When the substrate sheet 9 is in the form of a strip, the component supply sheet 20 can be wound to form a wound body.

[0178] Examples of objects to which the venting member 4 is configured include the housing of electronic devices and the housing of electrical components for vehicles. The venting member 4 can be configured on the outer and / or inner surface of the housing. In this case, the opening can be a vent and / or a sound-transmitting opening provided in the housing. Examples of electronic devices include wearable devices such as smartwatches and wristbands; various cameras including action cameras and security monitoring cameras; information and communication devices such as mobile phones, smartphones, and tablets; virtual reality (VR) devices; augmented reality (AR) devices; and sensor devices. Examples of electrical components for vehicles include lights and ECUs. However, the objects are not limited to the above examples.

[0179] Foreign objects such as dust particles and water droplets are prevented from passing through by the configuration of the breathable component 4.

[0180] Figure 14 The middle shows Figure 13 Example 1: A variation of the component supply sheet. Figure 14 The component supply piece 20 (20B) has, in addition to having Figure 11 In addition to being a breathable component 4, the breathable component 4E has the same characteristics as... Figure 13 The components supplied are of the same composition as sheet 20A.

[0181] Figure 15 The middle shows Figure 13 Example 2: A variation of the component supply sheet. Figure 15 The component supply sheet 20 (20C) has, in addition to having Figure 12 In addition to being a breathable component 4, the breathable component 4F has the same characteristics as... Figure 13 The components supplied are of the same composition as sheet 20A.

[0182] Example

[0183] The present invention will be further described in detail below through embodiments. The present invention is not limited to the embodiments shown below.

[0184] [Example 1]

[0185] Poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, RT18) was used as the thermoplastic resin. A plasticizer with a kinematic viscosity of 110 mmHg at 40°C was prepared. 2 / s of liquid paraffin (manufactured by MORESCO). Pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (manufactured by BASF Japan) was used as an antioxidant. A mixture of 50.0% by weight of thermoplastic resin, 49.8% by weight of plasticizer, and 0.2% by weight of antioxidant was obtained. The mixture was kneaded at 260°C for 30 minutes using a LABO PLASTOMILL (manufactured by Toyo Seiki Co., Ltd.) to obtain a homogeneous compound. 1.6g of the compound particles were sandwiched between two polyimide plates (150μm thick), further sandwiched between two stainless steel plates (3.0mm thick). The particles were then hot-pressed at 1.0kN for 5 minutes using a compression molding machine heated to 260°C to obtain a pressed body. The pressed body was cooled on a metal plate at 120°C to obtain a molded body. The molded body was annealed at 200°C for 60 minutes. Then, using a biaxial stretching machine, the annealed molded body was simultaneously biaxially stretched at a stretching temperature of 100°C and a stretching ratio of 2x (longitudinal) × 2x (transverse). The strain rate during stretching was 1% / s (0.655 mm / s) in both the longitudinal and transverse directions. This yielded a sheet. Stretching was performed 5 minutes after the molded body was placed in a furnace set to the stretching temperature. Finally, extraction was performed by immersing the sheet in methyl ethyl ketone (MEK) at room temperature for 2 minutes using MEK as the extraction solvent. This removed the plasticizer from the sheet. To suppress sheet shrinkage, the extraction was performed while the sheet was fixed in a stainless steel frame. Through the above operations, the porous membrane of Example 1 was obtained.

[0186] Figure 16A A figure (1000x magnification) showing the results of SEM observation of the surface of the porous membrane of Example 1. Figure 16B for Figure 16A A magnified view of a portion (2000x). Figure 16C A graph (1000x magnification) showing the results of SEM observation of the cross-section of the porous membrane of Example 1.

[0187] [Example 2]

[0188] The molded body obtained by cooling the pressed body on a metal plate at 120°C was annealed at 200°C for 30 minutes. In addition, the porous membrane of Example 2 was obtained by the same method as in Example 1.

[0189] [Example 3]

[0190] After obtaining the compound, 1.6 g of the compound particles were placed between two polyimide plates (150 μm thick), and further sandwiched between them by a stainless steel plate (3.0 mm thick). The particles were then hot-pressed using a compression molding machine heated to 260°C at 1.0 kN for 5 minutes to obtain a compressed body. The compressed body, sandwiched between the polyimide plates, was then contacted with water at 18°C ​​to cool it, thus obtaining a molded body. The molded body was annealed at 200°C for 60 minutes. In addition, the porous membrane of Example 3 was obtained using the same method as in Example 1.

[0191] [Example 4]

[0192] Poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, DX 845) was used as the thermoplastic resin. The cooled molded body was annealed at 180°C for 30 minutes. Otherwise, the porous membrane of Example 4 was obtained by the same method as in Example 3.

[0193] [Example 5]

[0194] As the thermoplastic resin, a resin obtained by mixing poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, DX 845) and poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, DX 820) at a mass ratio of 50:50 was used. Otherwise, the porous membrane of Example 5 was obtained by the same method as in Example 4.

[0195] [Comparative Example 1]

[0196] The molded body obtained by cooling the pressed body on a metal plate at 120°C was subjected to coaxial biaxial stretching without annealing. Otherwise, the porous membrane of Comparative Example 1 was obtained by the same method as in Example 1.

[0197] Figure 17A A figure (2000x magnification) showing the results of SEM observation of the surface of the porous membrane of Comparative Example 1. Figure 17B A graph (1000x magnification) showing the results of SEM observation of the cross-section of the porous membrane of Comparative Example 1.

[0198] [Comparative Example 2]

[0199] The cooled molded body was not annealed, but subjected to coaxial biaxial stretching. Otherwise, the porous membrane of Comparative Example 2 was obtained by the same method as in Example 4.

[0200] [Comparative Example 3]

[0201] The molded body obtained by cooling the pressed body on a metal plate at 120°C was annealed at 100°C for 60 minutes. Otherwise, a porous membrane of Comparative Example 3 was obtained using the same method as in Example 1.

[0202] [Comparative Example 4]

[0203] The cooled molded body was not annealed, but subjected to coaxial biaxial stretching. Otherwise, the porous membrane of Comparative Example 4 was obtained by the same method as in Example 3.

[0204] [Comparative Example 5]

[0205] Poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, MX 002) was used as the thermoplastic resin. A plasticizer with a kinematic viscosity of 110 mmHg at 40°C was used. 2 / s of liquid paraffin (manufactured by MORESCO). Pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (manufactured by BASF Japan) was used as an antioxidant. A mixture of 35.0 wt% thermoplastic resin, 64.7 wt% plasticizer, and 0.3 wt% antioxidant was obtained. The mixture was kneaded using LABO PLASTOMILL at 260°C for 30 minutes to obtain a homogeneous compound. 1.6 g of the compound particles were sandwiched between two polyimide sheets (150 μm thick), further sandwiched between two stainless steel sheets (3.0 mm thick), and then hot-pressed using a compression molding machine heated to 260°C at 1.0 kN for 5 minutes to obtain a pressed body. The pressed body, sandwiched between the polyimide sheets, was then contacted with water at 18°C ​​to cool it, thus obtaining a molded body. The molded body was annealed at 150°C for 30 minutes. Then, the annealed molded body was immersed in MEK at room temperature for 5 minutes for extraction to remove the plasticizer. Next, the molded body with the plasticizer removed was subjected to simultaneous biaxial stretching at a stretching temperature of 150°C and a stretching ratio of 3 times (longitudinal) × 3 times (transverse) using a biaxial stretching machine. The strain rate during stretching was 1% / s (0.655 mm / s) in both the longitudinal and transverse directions. A sheet was thus obtained. Through the above operations, a porous membrane of Comparative Example 5 was obtained.

[0206] [Comparative Example 6]

[0207] The porous membrane of Comparative Example 5 was annealed at 165°C for 5 minutes. Otherwise, the porous membrane of Comparative Example 6 was obtained by the same method as Comparative Example 5.

[0208] [Comparative Example 7]

[0209] Poly(4-methyl-1-pentene) resin (manufactured by Mitsui Chemicals, DX 845) was used as the thermoplastic resin. A plasticizer with a kinematic viscosity of 110 mmHg at 40°C was used. 2 / s of liquid paraffin (manufactured by MORESCO). Pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (manufactured by BASF Japan) was used as an antioxidant. A mixture of 55% by weight of thermoplastic resin, 44.5% by weight of plasticizer, and 0.5% by weight of antioxidant was obtained. The mixture was kneaded using LABO PLASTOMILL at 260°C for 30 minutes to obtain a homogeneous compound. 1.6g of the compound particles were sandwiched between two polyimide sheets (150μm thick), further sandwiched between two stainless steel sheets (3.0mm thick). The particles were then hot-pressed using a compression molding machine heated to 260°C at 1.0kN for 5 minutes to obtain a pressed body. The pressed body, sandwiched between the polyimide sheets, was contacted with water at 18°C ​​to cool it, thus obtaining a molded body. Next, the cooled molded body was immersed in MEK at room temperature for 5 minutes to perform an extraction operation, removing the plasticizer from the molded body. Then, using a biaxial stretching machine, the molded body after plasticizer removal was subjected to simultaneous biaxial stretching at a stretching temperature of 180°C and a stretching ratio of 3 times (longitudinal) × 3 times (transverse). The strain rate during stretching was 1% / s (0.655 mm / s) in both the longitudinal and transverse directions. This yielded a sheet. The sheet was annealed at 170°C for 5 minutes. Through the above operations, the porous membrane of Comparative Example 7 was obtained.

[0210] [Comparative Example 8]

[0211] The pressed body, sandwiched between polyimide plates, was air-cooled to obtain a molded body. Alternatively, a porous membrane for Comparative Example 8 was obtained using the same method as Comparative Example 7. It should be noted that in Comparative Example 8, the membrane cracked during stretching.

[0212] [Comparative Example 9]

[0213] Simultaneous biaxial stretching was performed on the molded body after plasticizer removal using a biaxial stretching machine at a stretching temperature of 170°C and a stretching ratio of 3 times (longitudinal) × 3 times (transverse). The strain rate during stretching was 1% / s (0.655 mm / s) in both the longitudinal and transverse directions. A sheet was thus obtained. In Comparative Example 9, the film cracked during stretching, therefore annealing was not performed. Otherwise, a porous membrane of Comparative Example 9 was obtained using the same method as Comparative Example 7.

[0214] [Comparative Example 10]

[0215] The pressed body, sandwiched between polyimide plates, was air-cooled to obtain a molded body. In addition, a porous membrane for Comparative Example 10 was obtained using the same method as Comparative Example 9. It should be noted that in Comparative Example 10, the membrane also cracked during stretching.

[0216] The manufacturing conditions of the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 10 are shown in Table 1.

[0217] Table 1

[0218] ※1: Plasticizer extraction and removal performed before stretching.

[0219] Using the methods described above for porous membranes, the thickness, air permeability, water pressure resistance, and cohesion of the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 10 were evaluated. The evaluation results are shown in Table 2.

[0220] Figure 18 The change (R1-R2) before and after the heat resistance test is represented by the change in the air permeability of the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 7 divided by the water pressure resistance.

[0221] Furthermore, using the method described above for porous membranes, tensile tests were conducted at 25°C to obtain the SS curves for the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 10, and the fracture strain and maximum stress were measured. The results are shown in Table 2.

[0222] Figure 19 The SS curves of the porous membranes of Examples 1 to 5 and Comparative Examples 1 to 4 are shown in the figure.

[0223] Table 2

[0224] ※2: Measurement could not be performed because the membrane cracked during stretching.

[0225] Using the method described above for porous membranes, the equivalent circle diameter of the nodes and the equivalent circle diameter of the pores were determined for the porous membranes of Examples 1 to 5, Comparative Examples 1 to 2, and Comparative Example 7. The results are shown in Table 3.

[0226] Table 3

[0227] As shown in Table 2, the porous membranes of Examples 1 to 5 exhibit a fracture strain of less than 15%, demonstrating a property of low elongation. Figure 19 It can be seen that in the porous membranes of Examples 1 to 5, no yield point was observed in the SS curve.

[0228] In addition, from Table 2 and Figure 18 It can be seen that the porous membranes in Examples 1 to 5 satisfy R1-R2≥-0.015, showing high heat resistance.

[0229] Depend on Figure 16C and Figure 17B The comparison shows that, compared with the porous membrane of Comparative Example 1, the porous membrane of Example 1 has more connection points between nodes or between blocky nodes in the thickness direction, and the pores are more aggregated. Based on this result, it can be inferred that for the porous membrane of Example 1, before stretching (step S5), by subjecting the formed body to an annealing treatment (step S4) at a temperature of 180°C to 200°C for 30 to 60 minutes, the parts that can become highly crystalline nodes and the parts that can become low-crystalline fibrils are easily aggregated. As a result, through stretching, a membrane is formed as shown in the figure. Figure 16C The structure shown has numerous connections between nodes or between block-like nodes, and a high concentration of pores, thus achieving a property of resistance to elongation. Furthermore, it is speculated that this is achieved through... Figure 16C The cross-sectional structures shown in Examples 1 to 5 demonstrate that the porous membranes achieve a cohesion of 0.1 N / 10 mm or higher.

[0230] In addition, by Figures 16A-16B and Figure 17A A comparison reveals that the porous membranes of both Example 1 and Comparative Example 1 have a tortoise-shell-like structure formed by multiple nodes and multiple fibrils on their surfaces. However, in the porous membrane of Example 1, island-like regions of different sizes formed by multiple nodes exist at random locations. Based on this result, it is inferred that for the porous membrane of Example 1, by subjecting the molded body to annealing at a temperature of 180°C to 200°C for 30 to 60 minutes (step S4) before stretching (step S5), the portions that can become highly crystalline nodes and the portions that can become low-crystalline fibrils tend to aggregate. As a result, through stretching, a structure resembling a tortoise-shell-like structure is formed. Figures 16A-16B The structure shown consists of island-like regions of varying sizes formed by multiple nodes located at random positions, thereby achieving high water resistance and high air permeability.

[0231] Based on the above results, it can be understood that the porous membranes of Examples 1 to 5 are suitable for suppressing changes in properties.

[0232] Industrial practicality

[0233] The technology of this invention can be applied, for example, to waterproof and breathable membranes, waterproof and sound-permeable membranes, and separators for energy storage devices.

Claims

1. A porous membrane, wherein, The porous membrane contains a fluorine-free thermoplastic resin as its main component. In a tensile test at 25°C, the fracture strain of the porous membrane was less than 15%.

2. The porous membrane according to claim 1, wherein, No yield point was observed in the stress-strain curves obtained in the tensile test.

3. The porous membrane according to claim 1, wherein, The thermoplastic resin is a polyolefin resin.

4. The porous membrane according to claim 1, wherein, The cohesive strength of the porous membrane is above 0.1 N / 10 mm.

5. The porous membrane according to claim 1, wherein, The porous membrane has a water pressure resistance greater than 140 kPa, and the air permeability of the porous membrane, expressed as a Grylls number, is less than 50 seconds / 100 mL.

6. The porous membrane according to claim 1, wherein, The porous membrane has multiple nodes and multiple fibrils, and the equivalent circle diameter of the nodes is 3.5 μm or more.

7. The porous membrane according to claim 6, wherein, The distance between the nodes is greater than 1.5 μm.

8. The porous membrane according to claim 1, wherein, The equivalent circle diameter of the pores in the porous membrane is 0.8 μm or more.

9. The porous membrane according to claim 5, wherein, When the value obtained by dividing the air permeability by the water pressure resistance is defined as ratio R1, and the value obtained by dividing the air permeability of the porous membrane after a heat resistance test at 200°C for 5 minutes by the water pressure resistance is defined as ratio R2, the following condition is satisfied: R1-R2≥-0.

015.

10. The porous membrane according to claim 1, wherein, When the surface of the porous membrane is observed using a scanning electron microscope, the porosity is greater than 30%.

11. The porous membrane according to claim 1, wherein, The porous membrane is a stretched membrane.

12. A breathable component, wherein, The breathable component has: The porous membrane according to any one of claims 1 to 11, and An adhesive layer that bonds to the porous membrane.

13. A component supply sheet, the component supply sheet comprising: a breathable member disposed on said surface of an object having an open surface; and a substrate sheet on which the breathable member is disposed, wherein, The breathable component has: A porous membrane having a shape that covers the opening when disposed on the surface; and An adhesive layer is bonded to the porous membrane. The porous membrane is the porous membrane according to any one of claims 1 to 11.

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