Moisture-permeable waterproof film

Abstract

To provide a moisture-permeable waterproof film excellent in air permeability, water resistance and oil resistance.SOLUTION: As a result of further studies, the present applicant has found that a nonwoven fabric having an apparent density of 0.13 to 0. 57g / cm3 is provided. It has been found that a moisture-permeable waterproof film having excellent air permeability, water resistance, and oil resistance can be provided by including a nonwoven fabric having such an apparent density. In addition, when the constituent fibers of the nonwoven fabric are polyolefin resin fibers, the water resistance and oil resistance of the nonwoven fabric can be improved. Furthermore, when the nonwoven fabric is reinforced by the laminated support layer, the nonwoven fabric is prevented from being unintentionally deformed or damaged even when water or oil adheres thereto. As a result, a moisture-permeable waterproof film having excellent air permeability, water resistance, and oil resistance can be provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a moisture-permeable waterproof membrane comprising a nonwoven fabric. [Background technology]

[0002] For example, automobiles (e.g., powertrains, motors, lights, and other equipment), communication devices (e.g., smartphones, personal computers), home appliances (e.g., shavers, video equipment, and audio equipment), various batteries such as lithium-ion secondary batteries, solar power generation equipment, etc. are equipped with vent filters equipped with breathable waterproof membranes to adjust the pressure difference between the inside and outside of the equipment.

[0003] The vent filter is equipped with a sheet-like moisture-permeable waterproof membrane, which is required to be breathable as well as water-resistant and oil-resistant to prevent moisture and oil from entering the interior of the device.

[0004] As a moisture-permeable waterproof membrane that can be used to form such a vent filter, for example, Japanese Patent Application Laid-Open No. 2018-143993 (Patent Document 1) discloses a laminated nonwoven fabric in which a support layer is laminated to a nonwoven fabric by an adhesive layer. The invention described in Patent Document 1 is characterized by optimizing the melting points of the components that make up the laminated nonwoven fabric and the basis weight of the adhesive layer. This prevents shrinkage and delamination of the laminated nonwoven fabric even in high-temperature environments, and improves its durability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-143993 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the prior art such as Patent Document 1, the physical properties of the nonwoven fabric itself that constitutes the moisture-permeable waterproof membrane have not been fully considered.

[0007] Therefore, there was a need to provide a moisture-permeable waterproof membrane that is excellent in breathability, water resistance, and oil resistance by optimizing the physical properties of the nonwoven fabric itself. [Means for solving the problem]

[0008] The present invention is "(Claim 1) Apparent density is 0.13 to 0.57 g / cm 3 A breathable waterproof membrane comprising a nonwoven fabric. (Claim 2) The moisture-permeable waterproof membrane according to claim 1, wherein the constituent fibers of the nonwoven fabric are polyolefin resin fibers. (Claim 3) The moisture-permeable waterproof membrane according to claim 1 or 2, wherein a support layer is laminated on the nonwoven fabric. [Effects of the Invention]

[0009] The moisture-permeable waterproof membrane according to the first aspect of the present invention has an apparent density of 0.13 to 0.57 g / cm 3 By using a nonwoven fabric having this apparent density, the moisture-permeable waterproof membrane has excellent breathability, water resistance, and oil resistance.

[0010] The moisture-permeable waterproof membrane according to the second aspect of the present invention has a nonwoven fabric made of polyolefin resin fibers, and thus the inclusion of this nonwoven fabric provides the moisture-permeable waterproof membrane with further improved water resistance and oil resistance.

[0011] In the moisture-permeable waterproof membrane according to the third aspect of the present invention, the nonwoven fabric is reinforced by the laminated support layer, which prevents the nonwoven fabric from unintentionally deforming or breaking even when water or oil adheres to the membrane, and the membrane is also excellent in breathability, water resistance, and oil resistance. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present invention, various configurations can be appropriately selected, for example, the following configurations. Note that, unless otherwise specified, the various measurements described in the present invention are performed under atmospheric pressure. Furthermore, measurements are performed under a temperature condition of 25°C. Unless otherwise specified, the various measurement results described in the present invention are measured to a value one digit smaller than the desired value, and the value is calculated by rounding off the value. Specifically, when the desired value is expressed to one decimal place, the value is measured to two decimal places, and the obtained value is rounded to one decimal place to calculate the value to one decimal place, and this value is used as the desired value. The upper and lower limits exemplified in the present invention can be combined in any combination.

[0013] The constituent fibers of the nonwoven fabric of the moisture-permeable waterproof membrane according to the present invention may be, for example, polyolefin resins (e.g., polyethylene, polypropylene, polyolefin resins in which part of the hydrocarbon is substituted with a cyano group or a halogen such as fluorine or chlorine, etc.), polymethylpentene, styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polyester resins, etc.), It can be made using known resins such as polyimide resins, polyamideimide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyethersulfone, etc.), fluorine resins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, and acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic esters or methacrylic esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.).

[0014] In particular, when the constituent fibers of the nonwoven fabric are polyolefin resin fibers, the water resistance and oil resistance of the nonwoven fabric are improved, and the moisture-permeable waterproof film is more excellent in water resistance and oil resistance, which is preferable.

[0015] These resins may be either linear or branched polymers, may be block copolymers or random copolymers, and may have any three-dimensional structure or crystallinity, without any particular limitations.Furthermore, the nonwoven fabric may contain, as its constituent fibers, fibers made of a mixed resin obtained by blending multiple resin components.

[0016] Furthermore, these resins may contain one or more additives as charging aids, such as hindered amine compounds, aliphatic metal salts (e.g., magnesium stearate, aluminum stearate, etc.), and unsaturated carboxylic acid-modified polymers. Among these additives, it is preferable to add a hindered amine compound, and specific examples thereof include poly{(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl){(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}}, polycondensation product of dimethyl succinate and bis(1,2,2,6,6-pentamethyl-4-piperidyl)2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate.

[0017] In particular, the inclusion of a polyolefin resin containing a charging aid provides excellent charging performance, resulting in lower pressure loss and superior collection performance, and is a moisture-permeable waterproof membrane that is easy to maintain its filtration performance for a long period of time, making it preferable.

[0018] The nonwoven fabric may also contain, as constituent fibers, known inorganic fibers such as silicone fibers, glass fibers, metal oxide fibers such as silica fibers, and metal fibers.

[0019] The constituent fibers of the nonwoven fabric can be obtained by known methods, such as melt spinning, dry spinning, wet spinning, direct spinning (melt-blowing, spunbonding, electrostatic spinning, etc.), a method of extracting fibers with a small fiber diameter by removing one or more resin components from composite fibers, or a method of beating fibers to obtain split fibers.

[0020] The constituent fibers may be composed of one type of resin or multiple types of resins. Fibers composed of multiple types of resins may be in the form of what are generally called composite fibers, such as core-sheath composite fibers, sea-island composite fibers, side-by-side composite fibers, and orange composite fibers.

[0021] The constituent fibers may include irregular cross-section fibers other than those having a substantially circular or elliptical cross-sectional shape. The irregular cross-section fibers may have a cross section that is hollow, polygonal such as a triangular shape, alphabetic such as a Y-shape, irregular, multi-lobed, symbolic such as an asterisk, or a shape combining multiple of these shapes.

[0022] When the nonwoven fabric contains heat-fusible fibers as constituent fibers, the constituent fibers of the nonwoven fabric are heat-fused together, which is preferable because it can impart strength and dimensional stability to the nonwoven fabric. Such heat-fusible fibers may be fully fusible heat-fusible fibers or partially fusible heat-fusible fibers in the same manner as the above-mentioned composite fibers (for example, core-sheath composite fibers in which the sheath component is heat-fusible).

[0023] For example, a fiber web can be prepared by a dry method in which the above-mentioned fibers are fed into a carding device or an air-laying device to entangle the fibers, or a wet method in which the fibers are dispersed in a solvent and laid into a sheet to entangle the fibers.

[0024] The constituent fibers of the prepared fiber web can be entangled and / or integrated to prepare a nonwoven fabric. Examples of methods for entangling and / or integrating the constituent fibers include bonding the constituent fibers with a binder, entangling them with needles or a water jet, and heat-fusing the constituent fibers with heat-fusible fibers by subjecting the fiber web to a heat treatment. The resins exemplified as those capable of forming the constituent fibers of the nonwoven fabric may also be used as the resin constituting the binder.

[0025] The heat treatment method can be appropriately selected, and examples thereof include a method of heating or heating and pressurizing using a roll device, a method of heating and pressurizing using a reliant press device, a method of heating using a heater such as an oven dryer, a far-infrared heater, a dry heat dryer, or a hot air dryer, and a method of irradiating infrared rays without pressure to heat the resin contained therein.

[0026] Alternatively, a nonwoven fabric can be prepared by spinning using a direct spinning method (such as a melt-blowing method, a spunbonding method, an electrospinning method, or a method in which a spinning solution and a gas flow are discharged in parallel to each other and then spinning (for example, the method disclosed in JP-A-2009-287138)), and collecting the spinning material.

[0027] In addition to the fiber web, a nonwoven fabric may also be subjected to the above-mentioned method of entangling and / or integrating the constituent fibers.

[0028] The average fiber diameter and fiber length of the fibers constituting the nonwoven fabric are not particularly limited, but can be adjusted as appropriate so that the water resistance and oil resistance of the nonwoven fabric are improved and the moisture-permeable waterproof membrane has superior water resistance and oil resistance.

[0029] The average fiber diameter of the fibers constituting the nonwoven fabric can be 0.1 to 50 μm, 0.5 to 30 μm, 1 to 10 μm, or 1.5 to 5 μm. The term "average fiber diameter" refers to the arithmetic mean value of the fiber diameters of 50 fibers measured using an optical microscope or electron microscope photograph of a measurement target area containing fibers. When the cross-sectional shape of a fiber is noncircular, the fiber diameter is considered to be the diameter of a circle having the same area as the cross-sectional area.

[0030] The fibers constituting the nonwoven fabric may be continuous fibers (fibers with no specific length) such as meltblown fibers, spunbond fibers, or directly spun fibers such as electrospun fibers. Alternatively, the constituent fibers may be staple fibers with a specific fiber length, which may be 5 to 120 mm, 10 to 100 mm, or 30 to 80 mm. The "fiber length" refers to the fiber length measured in accordance with Method C (direct method) specified in 8.4.1c) of JIS L1015:2021 "Test Method for Staple Chemical Fibers."

[0031] In addition, a nonwoven fabric made of fibers having a continuous length, or a nonwoven fabric made of a mixture of fibers having a continuous length and staple fibers having a specific fiber length, is preferable as it has lower pressure loss and excellent collection properties, and is a breathable waterproof membrane that is easier to maintain its filtration performance for a long period of time.

[0032] The various configurations of the nonwoven fabric, such as thickness and basis weight, are not particularly limited, but can be appropriately adjusted so that the improved water resistance and oil resistance result in a breathable waterproof membrane with superior water resistance and oil resistance.

[0033] The thickness may be 0.1 to 10 mm, 0.3 to 5 mm, or 1 to 3 mm. The thickness is defined as 5 cm in the direction perpendicular to the main surface. 2The thickness of a laminated object is measured by removing all parts of the laminate except for the object to be measured, and then measuring the thickness.

[0034] The basis weight is 10 to 500 g / m 2 and can be 30 to 300 g / m 2 and 50 to 200 g / m 2 The basis weight is the weight per square meter of the surface (principal surface) having the widest area of ​​the object to be measured. 2 When measuring the basis weight of a measurement object that constitutes a laminate, the basis weight of the measurement object can be determined by measuring the basis weight after removing everything other than the measurement object from the laminate.

[0035] The nonwoven fabric of the present invention has an apparent density of 0.13 to 0.57 g / cm 3 The apparent density (unit: g / cm 3 ) is a method of measuring the basis weight (unit: g / m) of a nonwoven fabric sample taken in sheet form with a main surface parallel to the main surface of the object to be measured. 2 ) and thickness (unit: mm). Then, the calculated basis weight (unit: g / m 2 ) by the thickness (unit: mm) and convert the obtained value.

[0036] The apparent density of the nonwoven fabric can be adjusted appropriately within the range specified in the present invention, but is preferably 0.15 to 0.50 g / cm. 3 and can be 0.20 to 0.45 g / cm 3 and can be 0.25 to 0.40 g / cm 3 It can be.

[0037] The moisture-permeable waterproof membrane may comprise a laminate in which a support layer is laminated on the nonwoven fabric of the present invention. The nonwoven fabric of the present invention is reinforced by the laminated support layer, which prevents the nonwoven fabric from unintentionally deforming or breaking even when water or oil adheres to the nonwoven fabric, and is therefore preferable as a moisture-permeable waterproof membrane with excellent breathability, water resistance, and oil resistance.

[0038] Such a laminate may be a laminated nonwoven fabric obtained by laminating multiple sheets of nonwoven fabric or multiple types of nonwoven fabric, or a laminate obtained by laminating a nonwoven fabric with a fabric (woven fabric, knitted fabric, breathable film, or breathable foam). Specifically, the method for laminating the nonwoven fabric of the present invention with another nonwoven fabric or fabric may be selected as appropriate, and examples include a method of simply laminating them together, a method of laminating them and then subjecting them to an entanglement process such as needle punching or hydroentanglement, a method of laminating them together by bonding them with a binder or hot melt web, and a method of laminating them together by melting heat-fusible fibers contained in the constituent fibers.

[0039] Furthermore, the laminate may be prepared by forming a new nonwoven fabric or cloth directly on the main surface of the nonwoven fabric of the present invention, or may be prepared by forming the nonwoven fabric of the present invention on the main surface of a new nonwoven fabric or cloth.

[0040] When the support layer is made of fibers, the types of resins constituting the fibers, the cross-sectional shape of the fibers, the fiber length and average fiber diameter of the fibers, the basis weight and thickness (and apparent density) of the support layer, and other configurations can be the same as those listed as possible configurations for the nonwoven fabric described above. In particular, since this results in a moisture-permeable waterproof membrane with superior water resistance and oil resistance, it is preferable that both the nonwoven fabric and the support layer are made of polyolefin-based resins.

[0041] The nonwoven fabric or laminate according to the present invention may contain additives such as flame retardants (halogen-based flame retardants, metal hydroxide-based flame retardants, phosphorus-based flame retardants), fragrances, pigments, antiviral agents, antibacterial agents, antifungal materials, photocatalytic particles, activated carbon, inorganic particles, etc. The additives may be bonded by a binder, bonded by melting the thermoplastic resin that constitutes the nonwoven fabric or laminate according to the present invention, or kneaded into the nonwoven fabric or laminate according to the present invention.

[0042] As a method for bonding the additive with a binder, for example, a method of applying a solution in which the additive is dissolved or a dispersion in which the additive is dispersed, either directly or in a foamed state, to the nonwoven fabric or laminate according to the present invention using a spray or a gravure roll, or a method of immersing the nonwoven fabric or laminate according to the present invention in the solution or dispersion can be used.

[0043] Thereafter, the solvent or dispersion medium is removed by any suitable method. For example, the solvent or dispersion medium can be evaporated and removed by heating in a heater such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer, or by leaving the mixture to stand under a reduced pressure. The heating temperature used to remove the solvent or dispersion medium is a temperature at which the solvent or dispersion medium can volatilize, and the upper and lower limits of the heating temperature are adjusted so as to prevent unintended deterioration of the components constituting the nonwoven fabric or laminate according to the present invention.

[0044] The nonwoven fabric (or a laminate including the nonwoven fabric) obtained as described above can be used alone as a moisture-permeable waterproof membrane. However, the nonwoven fabric (or a laminate including the nonwoven fabric) may also be used as a moisture-permeable waterproof membrane by providing a pre-filter layer or a back-filter layer. In this case, the materials constituting the pre-filter layer or back-filter layer can be selected appropriately, and for example, another nonwoven fabric, woven fabric, knitted fabric, breathable film, breathable foam, etc. can be used. The filter can be used as a vent filter having the moisture-permeable waterproof membrane described above.

[0045] Next, an example of a method for manufacturing a moisture-permeable waterproof membrane according to the present invention will be described. (Step 1) preparing a fiber web or nonwoven fabric; (Step 2) Apply heat or pressure, or heat and pressure, to the prepared fiber web or nonwoven fabric in the thickness direction until the apparent density of the nonwoven fabric becomes 0.13 to 0.57 g / cm 3 a process of adjusting the It can be prepared by a manufacturing method having the following steps.

[0046] The method for adjusting the apparent density of the nonwoven fabric can be selected as appropriate, and examples thereof include a method in which heat or pressure or heat and pressure are applied in the thickness direction by passing the nonwoven fabric through a roll device, a method in which heat or pressure or heat and pressure are applied in the thickness direction by passing the nonwoven fabric through a reliant press device, etc. When heat is applied in the thickness direction of the nonwoven fabric, the nonwoven fabric that has been subjected to the heat is cooled by, for example, allowing it to cool.

[0047] The nonwoven fabric according to the present invention can be used in a flat state, but it may also be used after undergoing secondary processing such as pleating or corrugating, edge banding, electrification, or hydrophilization. In this case, known electrification methods can be used, such as corona discharge treatment or a method of electrifying the nonwoven fabric by applying a force such as ultrasonic waves to the nonwoven fabric via a liquid such as water (water electrification).

[0048] In addition, by placing a nonwoven fabric in a frame, it may be used as a vent filter with a moisture-permeable waterproof membrane. [Example]

[0049] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0050] (Preparation of spunbond nonwoven fabric constituting the support layer) Volume resistivity is 10 16A commercially available hindered amine light stabilizer was mixed with 100 parts by mass of commercially available polypropylene resin with a resistivity of approximately Ω·cm, at a concentration of 4 parts by mass as an antistatic agent. The mixture was then spun using the spunbond method and collected to produce a spunbond nonwoven fabric (basis weight: 60 g / m). 2 ) was prepared.

[0051] Example 1 Volume resistivity is 10 16 A commercially available hindered amine light stabilizer was mixed with 100 parts by mass of commercially available polypropylene resin with a resistivity of approximately Ω·cm, at a concentration of 4 parts by mass as a charging aid. The mixture was then spun using the melt-blowing method and collected to prepare a melt-blown nonwoven fabric (average fiber diameter: 0.77 μm). Then, one main surface of the spunbonded nonwoven fabric and one main surface of the meltblown nonwoven fabric were brought into contact with each other and simply overlapped to prepare a laminate. The laminate was then subjected to a Reliant press (heating temperature: 140°C, pressure: 0.5 MPa) and then allowed to cool to obtain a laminate including a melt-blown nonwoven fabric with an adjusted thickness. The laminate prepared in this manner was used as a moisture-permeable waterproof membrane. The physical properties of the melt-blown nonwoven fabric and spunbond nonwoven fabric, each having an adjusted thickness, that constituted the moisture-permeable waterproof membrane (laminate) were as shown in Table 1.

[0052] Examples 2 to 6 In Examples 3 and 5 to 6, laminates including melt-blown nonwoven fabrics with adjusted thicknesses were obtained in the same manner as in Example 1, except that melt-blown nonwoven fabrics with changed basis weights were used. In addition, in Examples 2 and 4, the spinning conditions were changed to have an average fiber diameter of 1.79 μm, and a melt-blown nonwoven fabric with a changed basis weight was used. In the same manner as in Example 1, a laminate including a melt-blown nonwoven fabric with an adjusted thickness was obtained. Examples 7 to 12 In Examples 7 to 8 and 12, laminates comprising melt-blown nonwoven fabrics with adjusted thicknesses were obtained in the same manner as in Example 1, except that melt-blown nonwoven fabrics with altered basis weights were used and the pressure of the reliant press device was changed to 0.2 MPa. In addition, in Examples 9 to 11, laminates comprising melt-blown nonwoven fabrics with adjusted thicknesses were obtained in the same manner as in Example 1, except that the spinning conditions were changed to change the average fiber diameter to 1.79 μm and the basis weight to a melt-blown nonwoven fabric (except for Example 8), and the pressure of the reliant press device was changed to 0.2 MPa. The laminate prepared in this manner was used as a moisture-permeable waterproof membrane. The physical properties of the melt-blown nonwoven fabric and spunbond nonwoven fabric, each having an adjusted thickness, that constituted the moisture-permeable waterproof membrane (laminate) were as shown in Table 1.

[0053] [Table 1]

[0054] The breathability and water pressure when three drops of water leaked from each of the moisture-permeable waterproof membranes prepared as described above were measured as follows. The evaluation results, along with the basis weight and thickness of each moisture-permeable waterproof membrane, are summarized in Table 2.

[0055] (Method for evaluating breathability) The measurement object, such as a breathable waterproof membrane, is subjected to 6.8.1 (Fragile method) specified in L1913:2010 "General nonwoven fabric test method" and its air permeability (unit: cm 3 / cm 2 / sec) was measured with the spunbond nonwoven fabric side facing the measuring device. The higher the measured air permeability, the more breathable the waterproof membrane is. 3 / cm 2 / sec or more was judged to be highly breathable.

[0056] (Water resistance evaluation method) The moisture-permeable waterproof membrane was subjected to Method B (high water pressure method) of 7.1.2 of JIS L1092:2009 "Testing methods for waterproofness of textile products," and the water pressure (unit: kPa, hereafter referred to as water pressure at the time of leakage) when three water droplets leaked from the moisture-permeable waterproof membrane was measured. At this time, water pressure was applied from the spunbond nonwoven fabric side of the moisture-permeable waterproof membrane. The higher the water pressure, the more water-resistant the breathable waterproof membrane is. Generally, the higher the water resistance, the more water-repellent the membrane tends to be. Therefore, a breathable waterproof membrane with high water resistance is also considered to be highly oil-resistant (chemical-resistant). Therefore, breathable waterproof membranes with a water pressure of 8.00 kPa or higher at the time of leakage were judged to be highly water-resistant (and oil-resistant).

[0057] [Table 2]

[0058] (Examples 13 to 15) Volume resistivity is 10 16 A commercially available hindered amine light stabilizer was mixed as an antistatic agent in an amount of 4 parts by mass with 100 parts by mass of commercially available polypropylene resin having a resistivity of approximately Ω·cm. The mixture was then spun using a melt-blowing method and collected to prepare a melt-blown nonwoven fabric (average fiber diameter: 1.08 μm). In Examples 13 to 15, the basis weight of the melt-blown nonwoven fabric was varied. And the weight in between is 30g / m 2 A hot melt web (which melts at temperatures above 100°C) of ethylene-methacrylic acid copolymer resin was sandwiched between the two layers to prepare a laminate consisting of spunbond nonwoven fabric, hot melt web, and meltblown nonwoven fabric in that order. The laminate was then placed in a reliant press (heating temperature: 100°C, no pressure was applied), and then allowed to cool to obtain a laminate having a melt-blown nonwoven fabric with an adjusted thickness. The laminates prepared in this manner were used as moisture-permeable waterproof membranes. The physical properties of the melt-blown nonwoven fabric and spunbond nonwoven fabric constituting each moisture-permeable waterproof membrane (laminate) are shown in Table 3.

[0059] [Table 3]

[0060] The breathability and water pressure during leakage of each of the moisture-permeable waterproof membranes prepared as described above were measured as described above. The evaluation results, along with the basis weight and thickness of each moisture-permeable waterproof membrane, are summarized in Table 4.

[0061] [Table 4]

[0062] Example 16 Volume resistivity is 10 16 A commercially available hindered amine light stabilizer was mixed as a charging aid at 4 parts by mass with 100 parts by mass of commercially available polypropylene resin with a resistivity of approximately Ω·cm. The mixture was then spun using the melt-blowing method and collected to prepare a melt-blown nonwoven fabric (average fiber diameter: 1.08 μm). And the weight in between is 30g / m 2 A hot melt web (which melts at temperatures above 100°C) of ethylene-methacrylic acid copolymer resin was sandwiched between the two layers, and a laminate was prepared by simply laminating the spunbond nonwoven fabric, hot melt web, meltblown nonwoven fabric, hot melt web, and spunbond nonwoven fabric in that order. The laminate was then subjected to a Reliant press (heating temperature: 100°C, pressure: 0.5 MPa) and then allowed to cool to obtain a laminate including a melt-blown nonwoven fabric with an adjusted thickness. The laminate prepared in this manner was used as a moisture-permeable waterproof membrane. The physical properties of the meltblown nonwoven fabric and spunbonded nonwoven fabric constituting the moisture-permeable waterproof membrane (laminate) are shown in Table 5.

[0063] [Table 5]

[0064] The breathability and water pressure during leakage of the moisture-permeable waterproof membranes prepared as described above were measured as described above. The evaluation results, along with the basis weight and thickness of the moisture-permeable waterproof membranes, are summarized in Table 6.

[0065] [Table 6]

[0066] From the above results, the apparent density is 0.13 to 0.57 g / cm 3 The moisture-permeable waterproof membrane comprising the nonwoven fabric was found to have excellent breathability and water resistance (as well as oil resistance). [Industrial Applicability]

[0067] The moisture-permeable waterproof membrane of the present invention can be suitably used as a moisture-permeable waterproof membrane for adjusting the pressure difference between the inside and outside of devices in automobiles (e.g., powertrains, motors, lights, and other accessories), communication devices (e.g., smartphones, personal computers), home appliances (e.g., shavers, video equipment, and audio equipment), various batteries such as lithium-ion secondary batteries, solar power generation devices, etc. Furthermore, by using this moisture-permeable waterproof membrane, a vent filter that exhibits the above-mentioned effects can be prepared.

Claims

1. Apparent density of 0.13 to 0.57 g / cm ３ A breathable waterproof membrane comprising a nonwoven fabric.

2. 2. The moisture-permeable waterproof membrane according to claim 1, wherein the constituent fibers of the nonwoven fabric are polyolefin resin fibers.

3. The moisture-permeable waterproof membrane according to claim 1 or 2, wherein a support layer is laminated on the nonwoven fabric.

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