Air-permeable film, method for producing same, fabric, and protective clothing

Abstract

Provided is an air-permeable film which contains a thermoplastic resin and an inorganic filler, wherein, with respect to the particle size distribution of the inorganic filler, the particle size of the inorganic filler at the cumulative volume of 10% is more than 0.5 μm if the volume-based cumulative distribution is drawn from the smallest particle size side, and the particle size of the inorganic filler at the cumulative volume of 100% is 8 μm or less if the volume-based cumulative distribution is drawn from the smallest particle size side.

Description

Breathable film and its manufacturing method, fabric, and protective clothing

[0001] The present disclosure relates to a breathable film and a method for manufacturing the same, a fabric, and a protective garment.

[0002] Breathable films containing polyolefin resins and inorganic fillers have the ability to transmit substances such as gases and liquids, and are therefore gas-permeable when the substance is gas or vapor, and liquid-permeable when the substance is liquid. For this reason, breathable films are used in a wide variety of applications, such as hygiene materials, medical materials, clothing materials, building materials, separation membranes, agricultural breathable sheets, synthetic paper, and separators for various batteries.

[0003] However, further improvements are required in both applications. In particular, protective clothing for preventing infection used in medical settings and the like is known to use sheets made of flash-spun nonwoven fabrics in which polyethylene ultrafine mesh long fibers are randomly laminated. Disposable protective clothing made of such nonwoven fabrics is useful because it is light, flexible, and strong. However, protective clothing made of sheets made of flash-spun nonwoven fabrics has sometimes exhibited poor virus barrier properties.

[0004] Patent Document 1 describes a porous film or sheet made by stretching a resin containing calcium carbonate, in which the calcium carbonate particles have a particle size in the range of 0.5 μm to 3 μm and account for 50 mass % or more of the total particle amount, the maximum particle size is 8 μm or less, and the calcium carbonate particles have a shape in which the average L / D value is 1.6 or less, where L is the major axis and D is the minor axis, and the particle specific surface area is 15 m ２ The film or sheet is characterized in that the precipitated calcium carbonate has a water solubility of 1 / g or less.

[0005] Patent Document 2 discloses a microporous film comprising a polyolefin resin layer containing 40% by mass or more and 60% by mass or less of fine particles, a thickness of 40 μm or less, and voids between the surfaces of the fine particles and the polyolefin resin, wherein the fine particles have a particle size of 0.2 μm or more and 0.5 μm or less at 10% of the cumulative volume when subtracting the cumulative volume distribution from the small particle side in the particle size distribution, and a particle size of 6 μm or less at 100% of the cumulative volume when subtracting the cumulative volume distribution from the small particle side in the particle size distribution. Patent Document 2 also discloses protective clothing using a microporous film containing fine particles with small particle sizes and a narrow particle size distribution, thereby forming stable, small-sized micropores. It is disclosed that when protective clothing is made using this microporous film, it can be made to have excellent moisture permeability and water resistance, be comfortable to wear, and also have excellent blood barrier properties and virus barrier properties.

[0006] Patent Document 1: JP-A-8-225680 Patent Document 2: JP-A-2021-172726

[0007] However, in the porous film or sheet described in Patent Document 1, when the major axis of the calcium carbonate particles is L and the minor axis is D, the calcium carbonate particles have a shape with an average L / D value of 1.6 or less, so that when the calcium carbonate is aggregated during the formation of the porous film, if the thickness of the porous film is reduced, the porous film is prone to cracks and large holes are formed. ２ Although it is possible to reduce the weight of the porous film to a certain extent, it has been difficult to further reduce the basis weight of the porous film. Furthermore, since the porous film cannot be made even thinner, it has been difficult to improve productivity. Furthermore, the microporous film described in Patent Document 2 has limitations in its manufacturing method, such as the need to mold it by biaxial stretching because the particle size of the microparticles used is small and the particle size distribution is narrow. Furthermore, when laminating a fabric, the roll of the microporous film has a low ratio of mechanical properties in the machine direction to mechanical properties in the width direction, and the sheet unwound from the roll is prone to tearing, making continuous production difficult. For this reason, it has been difficult to maintain virus barrier properties in fabrics laminated with the microporous film.

[0008] The present disclosure has been made in view of the above circumstances, and an object of one aspect of the present disclosure is to provide a breathable film that has an excellent balance between virus barrier property and moisture permeability, and a method for producing the same. Another object of the present disclosure is to provide a fabric and protective clothing that use the breathable film.

[0009] (A) The breathable film according to the present disclosure includes the following embodiments <a1> to <a12>.

[0010] <a1> A breathable film containing a thermoplastic resin and an inorganic filler, wherein the particle size distribution of the inorganic filler has a particle size of more than 0.5 μm, which represents 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side, and a particle size of 8.0 μm or less, which represents 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side. <a2> The breathable film according to <a1>, wherein the particle size distribution of the inorganic filler has a particle size of more than 1.0 μm, which represents 50% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side. <a3> The breathable film according to <a1> or <a2>, wherein the particle size distribution of the inorganic filler includes a first peak having a maximum value A in the range of 1 μm or more. <a4> The breathable film according to <a3>, wherein the frequency of the particle size distribution at the position of the first peak is 10% or less. <a5> The breathable film according to <a3> or <a4>, wherein the inorganic filler further includes a second peak having a maximum value B in a range of less than 1 μm. <a6> The breathable film according to <a5>, wherein the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.0 or greater and less than 5.0. <a7> The breathable film according to any one of <a1> to <a6>, wherein the inorganic filler content is 40% by mass to 70% by mass. <a8> The breathable film according to any one of <a1> to <a7>, wherein the inorganic filler is at least one selected from the group consisting of calcium sulfate, calcium carbonate, and barium sulfate. <a9> The breathable film according to any one of <a1> to <a8>, wherein the breathable film has a virus barrier property of Class 5 or 6. <a10> A fabric comprising the breathable film according to any one of <a1> to <a9> and a nonwoven fabric selected from a spunbond nonwoven fabric, a meltblown nonwoven fabric, a wetlaid nonwoven fabric, a spunlace nonwoven fabric, a drylaid nonwoven fabric, a dry pulp nonwoven fabric, an airlaid nonwoven fabric, a flash-spun nonwoven fabric, an open-fiber nonwoven fabric, and a needle-punched nonwoven fabric. <a11> A protective garment comprising the fabric according to <a10>.<a12> A method for producing a breathable film, comprising: forming a resin composition containing a thermoplastic resin and an inorganic filler into a film to obtain the film; and stretching the film in at least one axial direction, wherein the inorganic filler has a particle size distribution in which the particle size at which a cumulative 10% of the volume of the inorganic filler is obtained by subtracting the cumulative volume distribution from the small particle size side is greater than 0.5 μm, and the particle size at which a cumulative 100% of the volume of the inorganic filler is obtained by subtracting the cumulative volume distribution from the small particle size side is 8.0 μm or less.

[0011] (B) The breathable film according to the present disclosure includes the following embodiments <b1> to <b11>.

[0012] <b1> A breathable film containing a thermoplastic resin and an inorganic filler, wherein the inorganic filler has, in a particle size distribution thereof, a first peak having a maximum value A in a range of 1 μm or more and a second peak having a maximum value B in a range of less than 1 μm, and wherein the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.5 or more and less than 5.0. <b2> The breathable film according to <b1>, wherein, in the particle size distribution of the inorganic filler, a particle size at which 10% of the cumulative volume distribution is obtained by subtracting the small particle size side from the small particle size side exceeds 0.5 μm. <b3> The breathable film according to <b1> or <b2>, wherein, in the particle size distribution of the inorganic filler, a particle size at which 50% of the cumulative volume distribution is obtained by subtracting the small particle size side from the small particle size side exceeds 1.0 μm. <b4> The breathable film according to any one of <b1> to <b3>, wherein, in the particle size distribution of the inorganic filler, the particle size at which cumulative volume distribution is 100% when subtracting the cumulative volume distribution from the small particle size side is 10 μm or less. <b5> The breathable film according to any one of <b1> to <b4>, wherein the frequency of the particle size distribution at the position of the second peak is 2% to 7%. <b6> The breathable film according to any one of <b1> to <b5>, wherein the content of the inorganic filler is 40% by mass to 70% by mass. <b7> The breathable film according to any one of <b1> to <b6>, wherein the inorganic filler is at least one selected from the group consisting of calcium sulfate, calcium carbonate, and barium sulfate. <b8> The breathable film according to any one of <b1> to <b7>, wherein the breathable film has a virus barrier property of protection level Class 5 or 6. <b9> A fabric comprising the breathable film according to any one of <1b> to <b8> and a nonwoven fabric selected from a spunbond nonwoven fabric, a meltblown nonwoven fabric, a wetlaid nonwoven fabric, a spunlace nonwoven fabric, a drylaid nonwoven fabric, a dry pulp nonwoven fabric, an airlaid nonwoven fabric, a flash-spun nonwoven fabric, an open-fiber nonwoven fabric, and a needle-punched nonwoven fabric. <b10> A protective garment comprising the fabric according to <b9>.<b11> A method for producing a breathable film, comprising: forming a resin composition containing a thermoplastic resin and an inorganic filler into a film to obtain the film; and stretching the film in at least one axial direction, wherein the inorganic filler has, in a particle size distribution of the inorganic filler, a first peak having a maximum value A in a range of 1 μm or more and a second peak having a maximum value B in a range of less than 1 μm, and the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.5 or more and less than 5.0.

[0013] (C) The breathable film according to the present disclosure includes the following embodiments <c1> to <c13>.

[0014] <c1> A breathable film containing a thermoplastic resin and an inorganic filler, wherein the total pore size distribution frequency of pores having pore sizes of 3 μm to 5 μm on the surface of the breathable film is 3.0% or less, and the breathable film has a virus barrier property of Class 5 or 6. <c2> The breathable film according to <c1>, wherein the particle size of the inorganic filler, which represents 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side, exceeds 0.5 μm. <c3> The breathable film according to <c1> or <c2>, wherein the particle size of the inorganic filler, which represents 50% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side, exceeds 1.0 μm. <c4> The breathable film according to any one of <c1> to <c3>, wherein the particle size of the inorganic filler, which represents 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side, is 10 μm or less. <c5> The breathable film according to any one of <c1> to <c4>, wherein the particle size distribution of the inorganic filler includes a first peak having a maximum value A in the range of 1 μm or more. <c6> The breathable film according to <c5>, wherein the frequency of the particle size distribution at the position of the first peak is 10% or less. <c7> The breathable film according to <c5> or <c6>, wherein the inorganic filler further includes a second peak having a maximum value B in the range of less than 1 μm. <c8> The breathable film according to any one of <c5> to <c7>, wherein the maximum value A of the first peak is greater than the maximum value B of the second peak. <c9> The breathable film according to any one of <c1> to <c8>, wherein the content of the inorganic filler is 40% by mass to 70% by mass. <c10> The breathable film according to any one of <1c> to <c9>, wherein the inorganic filler is at least one selected from the group consisting of calcium sulfate, calcium carbonate, and barium sulfate. <c11> A fabric comprising the breathable film according to any one of <c1> to <c10> and a nonwoven fabric selected from a spunbond nonwoven fabric, a meltblown nonwoven fabric, a wetlaid nonwoven fabric, a spunlace nonwoven fabric, a drylaid nonwoven fabric, a dry pulp nonwoven fabric, an airlaid nonwoven fabric, a flash-spun nonwoven fabric, an open-fiber nonwoven fabric, and a needle-punched nonwoven fabric. <c12> A protective garment comprising the fabric according to <c11>.<c13> A method for producing a breathable film, comprising: forming a resin composition containing a thermoplastic resin and an inorganic filler into a film to obtain a film; and stretching the film in at least one axial direction, wherein the film is a breathable film, and the total value of the pore size distribution frequency of pores having pore sizes of 3 μm to 5 μm on the surface of the breathable film is 3.0% or less, and the breathable film has a virus barrier property of a protection level of Class 5 or 6.

[0015] According to one aspect of the present disclosure, there are provided a breathable film having an excellent balance between virus barrier properties and moisture permeability, and a method for producing the same. Also, according to another aspect of the present disclosure, there are provided fabrics and protective clothing using the breathable film.

[0016] The present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0017] In the present disclosure, when a numerical range is indicated using "to", the numerical values ​​before and after "to" are included as the minimum and maximum values, respectively. In the present disclosure, when a numerical range is indicated in a stepped manner, the upper or lower limit value of one numerical range may be replaced with the upper or lower limit value of another stepped numerical range. Furthermore, in the present disclosure, when a numerical range is indicated, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, the particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, the term "laminated" refers to stacking layers, and two or more layers may be bonded or detachable. In the present disclosure, "(meth)acrylate" means at least one of acrylate and methacrylate. In the present disclosure, the stretching direction of the breathable film is referred to as the MD direction, and the direction perpendicular to the stretching direction is referred to as the CD direction.

[0018] [Breathable Film] The breathable film of the present disclosure is a breathable film containing a thermoplastic resin and an inorganic filler.

[0019] In one embodiment, the breathable film of the present disclosure is such that, in the particle size distribution of the inorganic filler, the particle size at which the cumulative 10% of the volume cumulative distribution is subtracted from the small particle size side is greater than 0.5 μm, and the particle size at which the cumulative 100% of the volume cumulative distribution is subtracted from the small particle size side is 8.0 μm or less (hereinafter, the breathable film of this embodiment may be referred to as the "breathable film of embodiment A").

[0020] In another embodiment, the breathable film of the present disclosure may be one in which the inorganic filler includes, in the particle size distribution of the inorganic filler, a first peak having a maximum value A in the range of 1 μm or more and a second peak having a maximum value B in the range of less than 1 μm, and the maximum value A of the first peak may be greater than the maximum value B of the second peak. In the above embodiment, the breathable film may be one in which the inorganic filler includes, in the particle size distribution of the inorganic filler, a first peak having a maximum value A in the range of 1 μm or more and a second peak having a maximum value B in the range of less than 1 μm, and the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) may be 1.5 or more and less than 5.0 (hereinafter, the breathable film of this embodiment may be referred to as the "breathable film of embodiment B").

[0021] Here, the peak having a maximum value means a point around which the frequency of the particle size distribution changes from increasing to decreasing.

[0022] In another embodiment, the breathable film of the present disclosure may have a surface in which the total pore size distribution frequency of pores having a pore size of 3 μm to 5 μm is 3.0% or less, and the breathable film may have a virus barrier property of Class 5 or 6 protection level (hereinafter, the breathable film of this embodiment may be referred to as the "breathable film of embodiment C").

[0023] In the following description, when referring to the "breathable film of the present disclosure," the breathable film of the present disclosure includes the breathable films including the above-mentioned embodiments A, B, and C, unless otherwise specified.

[0024] The breathable film of the present disclosure is useful for a wide variety of applications, such as hygiene materials, medical materials, clothing materials, building materials, separation membranes, agricultural breathable sheets, synthetic paper, separators for various batteries, etc. Furthermore, by laminating the breathable film of the present disclosure with a nonwoven fabric or the like to form a fabric, it can be usefully used as protective clothing.

[0025] The components constituting the breathable film of the present disclosure, the physical properties of the breathable film, etc. will be described in detail below.

[0026] <Thermoplastic Resin> The breathable film of the present disclosure contains a thermoplastic resin. The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin that can be used in breathable films. Examples of thermoplastic resins include polyolefin resins, polystyrene resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polyester resins, polycarbonate resins, polyamide resins, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, polymethylpentene resins, polyvinyl alcohol resins, cyclic olefin resins, polylactic acid resins, polybutylene succinate resins, polyacrylonitrile resins, polyethylene oxide resins, cellulose resins, polyimide resins, polyurethane resins, polyphenylene sulfide resins, polyphenylene ether resins, polyvinyl acetal resins, polybutadiene resins, polybutene resins, polyamideimide resins, polyamide bismaleimide resins, polyarylate resins, polyetherimide resins, polyetheretherketone resins, polyetherketone resins, polyethersulfone resins, polyketone resins, polysulfone resins, aramid resins, fluororesins, and polyacetal resins. Among these, polyolefin resins, ethylene-vinyl alcohol resins, polymethylpentene resins, polylactic acid resins, polyketone resins, fluororesins, polyacetal resins, etc. are preferred from the viewpoint of heat resistance.

[0027] Among thermoplastic resins, the breathable film of the present disclosure preferably contains a polyolefin resin from the viewpoints of flexibility, heat resistance, formation of continuous pores, environmental hygiene, odor, and the like.

[0028] Particularly preferred polyolefin resins for use in the breathable film of the present disclosure include (1) linear low-density polyethylene (hereinafter sometimes referred to as LLDPE), (2) low-density polyethylene (hereinafter sometimes referred to as LDPE), and (3) polypropylene (hereinafter sometimes referred to as PP). The polyolefin resin may be a mixture of LLDPE, LDPE, and PP.

[0029] (1) Linear low-density polyethylene, which constitutes the polyolefin resin, is a copolymer of ethylene and a small amount of α-olefin, and has a linear polyethylene main chain and short-chain branches having about 2 to 6 carbon atoms. The density of LLDPE is preferably 0.91 g / cm ３ ~0.94 g / cm ３ and 0.91 g / cm ３ ~0.93 g / cm ３ The melt index (MI) of the LLDPE is preferably 0.1 g / 10 min to 10 g / 10 min, more preferably 1.0 g / 10 min to 7.0 g / 10 min. When the density, or more preferably the density and MI, are within the above ranges, the breathable film will have excellent flexibility and breathability.

[0030] Here, the density is a density measured in accordance with JIS K 7112:1999 (Method for measuring density and specific gravity of plastics - non-foamed plastics), and the density of other resins is measured in the same manner. The MI is a value measured at 190°C under a load of 2.16 kg in accordance with ASTM D-1238, and the MI of other resins is measured in the same manner.

[0031] Specific examples of linear low-density polyethylene include copolymers of ethylene-propylene, ethylene-(1-butene), ethylene-(1-hexene), ethylene-(4-methyl-1-pentene), and ethylene-(1-octene).

[0032] The blending amount of (1) LLDPE contained in the polyolefin resin significantly affects the strength and bending resistance of the resulting breathable film, and is therefore preferably 20% to 50% by mass, and more preferably 25% to 45% by mass, when the total amount of the breathable film is taken as 100% by mass. If the blending amount of LLDPE is 50% by mass or less, the mechanical strength, such as the strength and bending resistance, of the stretched breathable film tends to be less likely to decrease. If the blending amount of LLDPE is 20% by mass or more, the bending resistance of the breathable film tends to be reduced.

[0033] Specific examples of LLDPE products include Evolue (SP1520, SP1540, SP2020, SP2040, SP2120, SP2540, SP3530) manufactured by Prime Polymer, Novatec LL (UF230, UF240, UF934) manufactured by Nippon Polyethylene, Dowlex (2035G, 2036P, 2047G) manufactured by Dow, and LLDPE (LSLH118, SLH218) manufactured by Braskem.

[0034] The density of (2) LDPE contained in the polyolefin resin is preferably 0.905 g / cm ３ ~0.960g / cm ３ LDPE can usually be synthesized by polymerizing ethylene under high pressure in the presence of a radical polymerization catalyst. ３ ~0.940g / cm ３ It is more preferable that the MI is 0.1 g / 10 min to 10 g / 10 min, and more preferably 0.2 g / 10 min to 2.0 g / 10 min. By having the density and, more preferably, the MI within the above ranges, the extrusion characteristics and moldability of the film, as well as the mechanical strength required for a breathable film, can be achieved.

[0035] The blending amount of (2) LDPE contained in the polyolefin resin is preferably 0.5% to 20% by mass of the total amount of the breathable film. More preferably, it is 1% to 10% by mass of the total amount of the breathable film. This blending amount affects the uniformity of the thickness of the resulting breathable film. When the amount of LDPE used is 20% by mass or less, the occurrence of pinholes tends to be suppressed. On the other hand, when the amount of LDPE used is 0.5% by mass or more, the uniformity of the thickness of the breathable film improves, and draw resonance tends to be less likely to occur in the breathable film.

[0036] Specific examples of LDPE products include Mirason (50P, F9673P) manufactured by Mitsui Dow Polychemicals, Suntec-LD (L11640, L2340A, L2340E) manufactured by Asahi Kasei, Novatec LD (LF128, LF441) manufactured by Nippon Polyethylene, Dowlex (2042G) manufactured by Dow, and LDPE (SEB853) manufactured by Braskem.

[0037] The polypropylene (3) contained in the polyolefin resin is not particularly limited, and may have a density of 0.890 g / cm ３ ~0.940g / cm ３ , preferably, the MI is 0.1 g / 10 min to 30 g / 10 min, and more preferably, the density is 0.890 g / cm ３ ~0.920g / cm ３ and MI is 1.0 g / 10 min to 10.0 g / 10 min. When the density and MI are within the above ranges, the resin composition can obtain film extrusion properties and molding processability, as well as the mechanical strength required for a breathable film.

[0038] (3) Polypropylene, which constitutes the polyolefin resin, is a propylene homopolymer or a copolymer of propylene and a small amount of other α-olefin. Specific examples include propylene homopolymer and propylene-ethylene copolymer.

[0039] The amount of (3) polypropylene contained in the polyolefin resin is preferably 0.5% to 25% by mass of the total amount of the breathable film, and more preferably 1% to 20% by mass of the total amount of the breathable film. Polypropylene is an important component for increasing the 5% elongation strength in the MD direction of the resulting breathable film. When the amount of polypropylene is 25% by mass or less of the total amount of the breathable film, the moisture permeability and texture of the breathable film tend to be improved. Furthermore, when the amount of polypropylene is 0.5% by mass or more of the total amount of the breathable film, the decrease in 5% elongation strength tends to be suppressed.

[0040] Specific examples of PP products include Prime Polypro (F103, F113G, F-704NP, etc.) manufactured by Prime Polymer, Suntec-LD (L1850K, etc.) manufactured by Asahi Kasei, Wintec (WFX4M, etc.) manufactured by Nippon Polypropylene, and Novatec PP (SA03, etc.) manufactured by Nippon Polypropylene. The polypropylene may be a commercially available product.

[0041] The polypropylene may be biomass-derived polypropylene. "Biomass-derived polypropylene" refers to polypropylene produced from raw material monomers including biomass-derived propylene. Biomass-derived polypropylene is a carbon-neutral material, and therefore can reduce the environmental impact of producing breathable films. Biomass-derived polypropylene can be obtained by known methods.

[0042] The biomass content of the polypropylene used as a raw material for the breathable film of the present disclosure is preferably 10% or more from the viewpoint of reducing the environmental load.

[0043] The polypropylene used as a raw material for the breathable film of the present disclosure may include polypropylene obtained by recycling, i.e., a so-called recycled polymer. The "recycled polymer" includes a polymer obtained by recycling waste polymer products, and can be produced, for example, by the method described in DE 10 2019 127 827 (A1). The recycled polymer may include a marker that identifies it as having been obtained by recycling.

[0044] The three polyolefins may be resins produced using a multi-site catalyst such as a Ziegler catalyst, or may be resins produced using a single-site catalyst such as a metallocene catalyst. In the present invention, the MI of the polyolefin resin blend consisting of (1) LLDPE, (2) LDPE, and (3) PP is preferably 1 g / 10 min to 10 g / 10 min.

[0045] <Inorganic Filler> The breathable film of the present disclosure contains an inorganic filler.

[0046] In the breathable film of the present disclosure, it is preferable to use an inorganic filler whose particle size, which represents 10% of the cumulative volume distribution when subtracting the small particle size side from the small particle size side in the particle size distribution, exceeds 0.5 μm in terms of improving virus barrier properties. For example, if small particles of 0.5 μm or less are present in a cumulative 10%, interparticle aggregation is likely to occur, and as a result, the pore size formed on the surface of the breathable film tends to be large. The particle size representing 10% of the cumulative volume distribution is more preferably 0.55 μm or more. From the viewpoint of improving virus barrier properties, it is preferable that the particle size representing 10% of the cumulative volume distribution be 1.15 μm or less.

[0047] In the breathable film of the present disclosure, it is preferable to use an inorganic filler having a particle size of more than 1 μm, which represents 50% of the cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, from the viewpoint of improving the moisture permeability of the breathable film when used as protective clothing. The particle size of 50% of the cumulative volume may be 2.5 μm or less, and may be 2.0 μm or less, from the viewpoint of improving virus barrier properties. For example, an inorganic filler having a particle size of more than 0.5 μm, which represents 10% of the cumulative volume, and a particle size of more than 1 μm but not more than 2.0 μm, which represents 50% of the cumulative volume, is one preferred embodiment from the viewpoint of achieving both virus barrier properties and moisture permeability.

[0048] In the breathable film of the present disclosure, the inorganic filler used has a particle size of 6.5 μm or less, more preferably 5.5 μm or less, and even more preferably 4.5 μm or less, at which the cumulative 98% particle size, when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, is cumulative. If the particle size at which the cumulative 98% particle size is within the above range, the virus barrier property tends to be higher. The particle size at which the cumulative 98% particle size is 2.5 μm or more. For example, from the viewpoint of improving virus barrier property, a preferred embodiment of the inorganic filler has a particle size at which the cumulative 10% particle size is greater than 0.5 μm and a particle size at which the cumulative 98% particle size is 2.5 μm or more and 4.5 μm or less.

[0049] In the breathable film of the present disclosure, the inorganic filler used preferably has a particle size of 10 μm or less, more preferably 9.0 μm or less, even more preferably 8.0 μm or less, and particularly preferably 7 μm or less, at which the cumulative volume distribution is 100% when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution. If the particle size at which the cumulative volume distribution is 100% is within the above range, the virus barrier property tends to be higher. Note that the particle size at which the cumulative volume distribution is 100% may be 5.0 μm or more.

[0050] When an inorganic filler is used, the particle size distribution has a particle size distribution in which the particle size at which the cumulative 10% of the volumetric cumulative distribution is obtained by subtracting the cumulative volumetric cumulative distribution from the small particle size side is greater than 0.5 μm, and the particle size at which the cumulative 100% of the volumetric cumulative distribution is obtained by subtracting the cumulative volumetric cumulative distribution from the small particle size side is 10 μm or less, resulting in superior virus barrier properties. The reason for this is presumed to be as follows: When a considerable amount of relatively small particles of 0.5 μm or less are present as an inorganic filler, the relatively small particles tend to gather around particles with a particle size of 1 μm or more, forming aggregates. Although the original particle size distribution can be observed by applying ultrasonic vibrations or a laser beam, aggregates are also formed during film formation, and it is thought that pore sizes are configured on the film surface according to the particle size distribution including the aggregates, resulting in the expression of virus barrier properties.

[0051] In the present disclosure, the particle size distribution of the inorganic filler is measured using a laser diffraction particle size distribution analyzer. To measure the particle size distribution of the inorganic filler, for example, a laser diffraction / scattering particle size analyzer (Microtrac-Bell MT3300II, LOW-WET, measurement range: 0.02 μm to 2000 μm, number of channels: 138) can be used. From the obtained particle size distribution, the positions of the first and second peaks; the particle size distribution frequencies at the positions of the first and second peaks (i.e., maximum values ​​A and B); and the particle sizes at cumulative 100%, cumulative 50%, cumulative 98%, and cumulative 10% can be determined.

[0052] The inorganic filler used in the breathable film of the present disclosure has, in its particle size distribution, a first peak having a maximum value A in the range of 1 μm or more and / or a second peak having a maximum value B in the range of less than 1 μm, and in the case where the second peak is included, it is preferable that the maximum value A of the first peak is larger than the maximum value B of the second peak, from the viewpoint of achieving both virus barrier properties and moisture permeability of the breathable film when used as protective clothing. In the present disclosure, "the maximum value of the first peak is larger than the maximum value of the second peak" means that, in the particle size distribution of the inorganic filler, the frequency of the particle size distribution at the peak position of the first peak is higher than the frequency of the particle size distribution at the peak position of the second peak.

[0053] In one embodiment of the present disclosure, it is preferable to use an inorganic filler whose particle size distribution includes a first peak having a maximum value in the range of 1 μm or more and a second peak having a maximum value in the range of less than 1 μm.

[0054] The maximum value A of the first peak is preferably in the range of 1 μm to 5 μm, and more preferably in the range of 1 μm to 4 μm. By setting the position of the maximum value A of the first peak within the above range, the moisture permeability and virus barrier properties tend to be excellent (for example, the virus barrier properties may have a Class 4 protection level). If the maximum value B of the second peak is in the range of 0.2 μm to 1.5 μm, the virus barrier properties tend to be excellent (for example, the virus barrier properties may have a Class 4 protection level). From the viewpoint of virus barrier properties and moisture permeability, it is more preferably in the range of 0.3 μm to less than 1.0 μm, and even more preferably in the range of 0.5 μm to less than 1.0 μm. The ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is preferably in the range of 1.0 to less than 5.0, more preferably in the range of 1.5 to less than 5.0, and even more preferably in the range of 1.5 to 3.0. When the maximum value A / maximum value B is in the above range, the virus barrier property tends to be improved.

[0055] In particular, when the maximum value A of the first peak is 1 μm or more, the maximum value B of the second peak is less than 1 μm, and the ratio of maximum value A / maximum value B is within the range of 1.5 to less than 5.0, the virus barrier property can achieve a protection level of Class 5 or 6. The estimated mechanism is that using medium to large particles with a maximum value of 1 μm or more (excluding large particles that may contribute to pore sizes unsuitable for virus barrier property) in an amount 1.5 to less than 5.0 times the amount of small to medium particles with a maximum value of less than 1 μm means a relatively broad particle size distribution. The breathable film of the present disclosure includes embodiments A, B, and C. However, based on the technical concept of the present disclosure, it is not limited to embodiments A, B, and C, and an appropriate combination of various factors generally known to suppress aggregate formation is one preferred embodiment. In combining these factors, for example, the shape of the inorganic filler, the type and amount of dispersant and surface treatment agent added to the inorganic filler, or the viscosity of the thermoplastic resin composition can be appropriately adjusted.

[0056] In the present disclosure, the inorganic filler used may have a particle size distribution frequency at the first peak position (i.e., maximum value A) of 10% or less. Of these, 7% or less is preferable. If the particle size distribution frequency at the first peak position is 10% or less (preferably 7% or less), the filler tends to have excellent virus barrier properties (for example, if an inorganic filler is used that has a particle size distribution in which the particle size at which the cumulative volume distribution is 100% when subtracting the small particle size side from the cumulative volume distribution is 10 μm or less, the filler may have a virus barrier Class 4 protection level).

[0057] In the present disclosure, by using an inorganic filler having a particle size distribution frequency at the second peak position (i.e., maximum value B) of 2.0% to 7.0%, excellent virus barrier properties tend to be achieved. In particular, it is preferable to use one having a frequency of 3.0% to 5.0%, and more preferably 3.0% to 4.5%. If the frequency of the particle size distribution at the second peak position is within the above range, the virus barrier properties tend to be even better.

[0058] In the breathable film of the present disclosure, the particle size distribution of the inorganic filler in the breathable film of embodiment A has a particle size at which the cumulative 10% of the volume of the inorganic filler is greater than 0.5 μm when subtracting the cumulative volume distribution from the small particle size side, and a particle size at which the cumulative 100% of the volume of the inorganic filler is greater than 8.0 μm when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment A, the particle size distribution of the inorganic filler has a particle size at which the cumulative 50% of the volume of the inorganic filler is greater than 1.0 μm when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment A, the particle size distribution of the inorganic filler preferably includes a first peak having a maximum value A in the range of 1 μm or more. In one embodiment of the breathable film of embodiment A, the frequency of the particle size distribution at the position of the first peak is preferably 10% or less. In one embodiment of the breathable film of embodiment A, the inorganic filler preferably further includes a second peak having a maximum value B in the range of less than 1 μm. In one aspect of the breathable film of embodiment A, the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is preferably 1.0 or more and less than 5.0.

[0059] In the present disclosure, the breathable film of embodiment B described above has a particle size distribution of the inorganic filler, which includes a first peak having a maximum value A in the range of 1 μm or more and a second peak having a maximum value B in the range of less than 1 μm, and the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.5 or more and less than 5.0. In one aspect of the breathable film of embodiment B, in the particle size distribution of the inorganic filler, the particle size at which the cumulative volume distribution is 10% when subtracted from the small particle size side is preferably greater than 0.5 μm. In one aspect of the breathable film of embodiment B, the particle size distribution of the inorganic filler, the particle size at which the cumulative volume distribution is 50% when subtracted from the small particle size side is preferably greater than 1.0 μm. In one aspect of the breathable film of embodiment B, the particle size at which the cumulative volume distribution is 100% when subtracted from the small particle size side is preferably 10 μm or less. In one aspect of the breathable film of embodiment B, the frequency of the particle size distribution at the position of the second peak is preferably 2% to 7%.

[0060] In the breathable film of the present disclosure, the inorganic filler preferably has a particle size of greater than 0.5 μm, which represents a cumulative 10% of the particle size distribution of the inorganic filler when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment C, the inorganic filler preferably has a particle size of greater than 1.0 μm, which represents a cumulative 50% of the particle size distribution of the inorganic filler when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment C, the inorganic filler preferably has a particle size of 100% of the particle size distribution when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment C, the inorganic filler preferably has a particle size distribution of 100% of the particle size distribution when subtracting the cumulative volume distribution from the small particle size side. In one embodiment of the breathable film of embodiment C, the inorganic filler preferably has a particle size distribution having a first peak with a maximum value in the range of 1 μm or more. In one embodiment of the breathable film of embodiment C, the frequency of the particle size distribution at the position of the first peak is preferably 10% or less. In one embodiment of the breathable film of embodiment C, the inorganic filler preferably further has a second peak with a maximum value in the range of less than 1 μm. In one aspect of the breathable film of embodiment C, the maximum value A of the first peak is preferably greater than the maximum value B of the second peak.

[0061] In the breathable film of the present disclosure, the specific surface area of ​​the inorganic filler is 1 m2 or less from the viewpoint of sufficient dispersibility and ease of handling when made into a resin composition. ２ / g to 30m ２ / g is preferred, and 1m ２ / g to 10m ２ When the specific surface area of ​​the inorganic filler is within the above range, it tends to have an excellent virus barrier property. The reason for this is not clear, but when the specific surface area of ​​the inorganic filler is 1 m ２ This is presumably because, compared with when the average particle size of the inorganic filler is less than 1 / g, the average particle size of the inorganic filler is smaller, and the minor axis of the pores formed in the film by the inorganic filler is smaller, which makes the minimum width of the flow path that penetrates the film formed by the interconnected pores relatively smaller, making it more difficult for viruses to pass from one side of the film to the other.

[0062] In this disclosure, the specific surface area of ​​an inorganic filler refers to the BET specific surface area measured by the nitrogen adsorption method. The specific surface area of ​​an inorganic filler can be measured, for example, using a specific surface area meter, BELSOROP-max II, manufactured by Microtrac-Bell. When the inorganic filler is a mixture of two or more types, the specific surface area of ​​the inorganic filler is the value for the mixture.

[0063] Known inorganic fillers can be used in the breathable film of the present disclosure. Examples include calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, magnesium hydroxide, aluminum hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica, and talc. Of these, calcium sulfate, calcium carbonate, and barium sulfate are preferred from the standpoint of cost performance, and calcium carbonate, which has a higher specific gravity than barium sulfate, is more preferred from the standpoint of reducing the weight per unit area. These inorganic fillers may be used alone or in combination of two or more. It is preferable that the inorganic fillers that mainly constitute the first peak and the second peak are the same type of inorganic filler. For example, it is not a preferred embodiment of the breathable film of the present disclosure that the inorganic filler that mainly constitutes the first peak is calcium carbonate and the inorganic filler that mainly constitutes the second peak is titanium oxide. Here, "mainly" refers to an inorganic filler that constitutes 80% or more of the inorganic fillers that constitute each peak.

[0064] The content of the inorganic filler in the breathable film can be 40% by mass to 70% by mass, preferably 56% by mass to 60% by mass, and more preferably 56% by mass or more but less than 60% by mass. If the content of the inorganic filler in the breathable film is 40% by mass or more, the film tends to have excellent moisture permeability. If the content of the inorganic filler in the breathable film is 70% by mass or less, the film tends to have excellent virus barrier properties.

[0065] When calcium carbonate and other inorganic fillers are used in combination as the inorganic filler, the proportion of calcium carbonate in the inorganic filler is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 99% by mass or more. The proportion of calcium carbonate in the inorganic filler may be 100% by mass.

[0066] Calcium carbonate used in breathable films can be produced by either wet or dry grinding, with wet grinding being preferred from the viewpoint of controlling the particle size distribution of calcium carbonate. Known production methods can be used for wet grinding calcium carbonate. Examples of dry grinding include jet mills, vibration mills, and ball mills. Examples of wet grinding include beads mills and ball mills, with beads mills being preferred. The solvent used in wet grinding is not particularly limited. For example, water or an organic solvent can be used. Examples of organic solvents include aliphatic alcohols having 1 to 3 carbon atoms, such as methanol, ethanol, and propanol; ketones, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters, such as ethyl acetate. Inorganic fillers other than calcium carbonate can also be produced in the same manner as calcium carbonate.

[0067] It is preferable to use an inorganic filler having an organic dispersant attached to its surface from the viewpoint of increasing the water dispersibility of the inorganic filler produced by a wet process, and also from the viewpoint of improving the dispersibility of the inorganic filler in the polyolefin resin.

[0068] Examples of organic dispersants that can be used include cationic organic dispersants (CD), anionic organic dispersants (AD), nonionic organic dispersants (ND), and mixtures of at least two of these. Examples of cationic organic dispersants (CD) used as organic dispersants include primary to tertiary amine salt-type cationic low-molecular-weight or polymeric surfactants and quaternary ammonium salt-type cationic low-molecular-weight or polymeric surfactants. Examples of primary to tertiary amine salt-type low-molecular-weight surfactants include higher alkylamine salts, higher alkylamine ethylene oxide adducts, higher alkylamine ethylene oxide / propylene oxide adducts, Solomin A-type amine salts, Sapamine A-type amine salts, Arcobel A-type amine salts, and imidazoline-type amine salts. Examples of quaternary ammonium salt-type low-molecular-weight surfactants include higher alkyltrimethylammonium salts, alkyldimethylbenzylammonium salts, Sapamine-type quaternary ammonium salts, imidazoline-type quaternary ammonium salts, and alkylpyridium salts.

[0069] Examples of primary to tertiary amine salt type polymeric surfactants include polyethyleneimine, polyalkylene polyamine salts, polyamine-dicyandiamide condensation salts, and polydiallylamine salts. Examples of quaternary ammonium salt type polymeric surfactants include polystyrene methylaminotrimethylammonium salts, polydiallyldimethylammonium salts, trimethylaminoethyl (meth)acrylate ammonium salts, and poly N-alkylpyridine salts.

[0070] Of these cationic surfactants, primary to tertiary amine salt-type polymeric surfactants or quaternary ammonium salt-type polymeric surfactants are preferred in order to obtain a high-concentration slurry during wet grinding. Particularly preferred are salts of diallylamine alone or copolymers with vinyl compounds, and polydiallyldimethylammonium salts incorporating alkyl groups such as octyl, lauryl, and stearyl. Preferred polymeric surfactants include cationic copolymer dispersants of diallyldimethylammonium chloride-acrylamide copolymers. The molecular weight of these polymeric surfactants is not particularly limited, but is preferably 1,000 to 150,000.

[0071] Examples of anionic organic dispersants (AD) used as organic dispersants include low-molecular-weight or polymeric surfactants having carboxylate, sulfate, sulfonate, and phosphate functional groups. Examples of low-molecular-weight carboxylates include higher fatty acid salts such as sodium laurate, sodium stearate, and sodium oleate, higher alcohol polyethylene oxide ether acetates, and perfluoroalkyl carboxylates. Examples of polymeric carboxylates include polyacrylates, salts of polyacrylic acid-maleic acid copolymers, and other carboxylic acid monomers alone or as copolymers of at least two or more carboxylic acid monomers, or their salts; copolymers of vinyl compounds and carboxylic acid monomers, or their salts; and carboxymethyl cellulose. Examples of low-molecular-weight sulfates include higher alcohol polyethylene oxide sulfates, sulfated oils, sulfated fatty acid esters, sulfated fatty acids, sulfated olefins, and alkylphenol polyethylene oxide sulfates.

[0072] Examples of low molecular weight sulfonates include alkylbenzene sulfonates, α-olefin sulfonates, alkane polysulfonates, perfluoroalkyl sulfonates, Igehon T type and aerosol type, and examples of high molecular weight sulfonates include formalin condensates of naphthalene sulfonates, polystyrene sulfonates, polyvinyl sulfonates, polyaryl sulfonates, and salts of copolymers of acrylamide and acrylamidopropane sulfonic acid.

[0073] Examples of copolymer-type polymer surfactants include copolymers composed of carboxylic acid monomers and sulfonic acid monomers, and salts thereof. Examples of low-molecular-weight phosphate ester salts include higher alcohol monophosphate ester salts, higher alcohol polyethylene oxide phosphate ester salts, and alkylphenol polyethylene oxide phosphate ester salts.

[0074] Among these anionic surfactants, polymeric surfactants are preferred in order to obtain a high-concentration slurry during wet grinding, and particularly preferred are carboxylic acid monomers alone or copolymers of at least two of them or their salts, such as polyacrylic acid or its salts, and polyacrylic acid-maleic acid copolymers or their salts. There are no particular restrictions on the molecular weight of these surfactants, but it is preferably 1,000 to 150,000.

[0075] Nonionic organic dispersants (ND) used as organic dispersants include polyethylene glycol-type and polyhydric alcohol-type nonionic surfactants. Examples of polyethylene glycol-type surfactants include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, fatty acid amide ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, and polyether-modified silicones.

[0076] Examples of polyhydric alcohol-type dispersants include fatty acid esters of glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, polyglycerin fatty acid esters or their ethylene oxide adducts, and fatty acid amides of alkanolamines, as well as methyl cellulose (MC), hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyalkylene oxide vinyl ether compounds, and polyhydroxylalkyl (meth)acrylates. These dispersants coat the inorganic filler and can therefore function as surface treatment agents.

[0077] The inorganic filler used in the breathable film of the present disclosure may be surface-treated to improve dispersibility in the thermoplastic resin (preferably a polyolefin resin), promote interfacial peeling with the thermoplastic resin, and prevent absorption of moisture from the outside. The surface treatment agent is preferably one that can hydrophobize the surface of the inorganic filler by coating it. Examples of surface treatment agents include higher fatty acids such as stearic acid, lauric acid, and 12-hydroxyoctadecanoic acid.

[0078] <Functional Additives> To the breathable film of the present disclosure, functional additives such as antioxidants, stretching aids such as mineral-based, plant-based, animal-based, synthetic, and petroleum-based waxes, stabilizers, colorants, light stabilizers, flame retardants, antistatic agents, deodorizers, antibacterial agents, etc. may be added, as long as the addition does not interfere with the object of the present disclosure. Of these functional additives, it is particularly desirable to incorporate an antioxidant from the viewpoint of quality stability.

[0079] The amount of functional additives containing antioxidants added is not particularly limited. In order to exhibit the function of the functional additives, the amount of functional additives added is preferably 0.1% by mass or more relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. On the other hand, from the viewpoint of productivity, the amount of functional additives added is preferably 5% by mass or less relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. The amount of functional additives added is preferably 0.1% by mass to 5% by mass relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler.

[0080] The antioxidant used in the breathable film of the present disclosure is not particularly limited, and a general antioxidant can be used.

[0081] Examples of antioxidants include phenolic antioxidants and hindered phenolic antioxidants, phosphite antioxidants, amine antioxidants and hindered amine antioxidants, thioether antioxidants, metal deactivators, etc. These may be used alone, but are more preferably used in combination to exert a synergistic effect.

[0082] Examples of phenol-based antioxidants and hindered phenol-based antioxidants include Adekastab (AO-20, AO-30, AO-40, AO-50, AO-60, AO-80, AO-330) manufactured by ADEKA, Irganox (1010, 1076, 1098) manufactured by BASF Japan, and Hostanox (O3, O310) manufactured by Clariant Chemicals. Examples of phosphite-based antioxidants include Adekastab PEP series (phosphite-based) manufactured by ADEKA, Irgafos (12, 38, 168, PEP-8, PEP-36, HP-10, 2112, 1178, 1500, C, 135A, 3010, P-EPQ) manufactured by BASF Japan, and Hostanox (P-EPQ) manufactured by Clariant Chemicals. Examples of amine-based antioxidants and hindered amine-based antioxidants include the Adekastab LA series (hindered amine-based) manufactured by ADEKA, Nylostab (S-EED) manufactured by Clariant Chemicals, and Hostavin (NOW, 3050, N30) manufactured by Clariant Chemicals. Examples of thioether-based antioxidants include the Adekastab AO series (thioether-based) manufactured by ADEKA. Examples of metal deactivators include the Adekastab ZS series manufactured by ADEKA and Hostanox (OSP1) manufactured by Clariant Chemicals. These antioxidants may be commercially available products, or effective chemicals may be used.

[0083] Since the incorporation of these antioxidants into the breathable film of the present disclosure can prevent oxidative degradation, the incorporation of an antioxidant is preferred from the viewpoint of the stability of the physical properties and quality of the breathable film. The amount of antioxidant to be incorporated is not particularly limited. In order to exert the function of the antioxidant, the amount of antioxidant to be incorporated is preferably 0.1% by mass or more relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. On the other hand, from the viewpoint of improving the productivity of the breathable film, the amount of antioxidant to be incorporated is preferably 3% by mass or less relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. The amount of antioxidant to be incorporated is preferably 0.1% by mass to 3% by mass relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler.

[0084] Examples of stretching aids include hydrogenated castor oil and its main component, 12-hydroxystearic acid triglyceride; dehydrated castor oil; esters of glycerin with a fatty acid mixture containing at least 30% by weight of 9,11-octadecadienoic acid and at least 30% by weight of 9,12-octadecadienoic acid, with a total of at least 70% by weight of both acids; liquid ethylene-α-olefin oligomers; ethylene bisstearamide; methylene bisstearamide; mixtures thereof; higher fatty acids such as stearic acid and lauric acid; and higher fatty acid metal salts such as calcium stearate. These components are used particularly to improve the stretchability and thickness uniformity of the breathable film. These stretching aids may be used alone or in combination of two or more.

[0085] The blending amount of the stretching aid is not particularly limited. In order to exhibit the function of the stretching aid, the blending amount of the stretching aid is preferably 0.1% by mass or more relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. On the other hand, from the viewpoint of improving the productivity of the breathable film, the blending amount of the stretching aid is preferably 3% by mass or less relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler. The blending amount of the stretching aid is preferably 0.1% by mass to 3% by mass relative to 100% by mass of the resin composition containing the polyolefin resin and the inorganic filler.

[0086] <Physical Properties and Performance of Breathable Film> In the present disclosure, the virus barrier property is evaluated by taking three 100 mm x 100 mm square evaluation samples from the breathable film, conducting a virus barrier property test in accordance with Procedure B of JIS T8061:2015, 8.8 (Exposure of materials to bacteriophage load test suspension), and evaluating the virus barrier property in accordance with JIS T8122:2015, 6.3.3 (Bacteriophage penetration resistance). In the above evaluation, the virus barrier protection levels are classified into Classes 1 to 6. The breathable film of the present disclosure has a virus barrier protection level of Class 5 or 6, and preferably has a virus barrier protection level of Class 6.

[0087] The breathable film of the present disclosure has a moisture permeability of 200 g / (m ２・h)~600g / (m ２ .h), and 280 g / (m ２ ・h)~500g / (m ２ h), and more preferably 350 g / (m ２ ・h)~450g / (m ２ h), and more preferably 370 g / (m ２ ・h)~450g / (m ２ It is even more preferable that the moisture permeability is 200 g / (m ２ On the other hand, if the moisture permeability is 350 g / (m ２ ・h)~600g / (m ２ In the present disclosure, the moisture permeability refers to a value measured by the method specified in JIS L1099:2012 A-1 (calcium chloride method).

[0088] The thickness of the breathable film of the present disclosure is preferably 15.0 μm to 35.0 μm, more preferably 20.0 μm to 30.0 μm, and even more preferably 24.0 μm to 28.0 μm. If the breathable film has a thickness of 15.0 μm or more, it tends to have excellent virus barrier properties. If the breathable film has a thickness of 35.0 μm or less, it tends to have excellent moisture permeability. The thickness of the nonwoven fabric can be determined as follows. Five 5 mm x 5 mm square samples are randomly obtained from the measurement subject, the thicknesses are measured, and the average value is calculated, and the obtained value is the thickness of the breathable film. The thickness is measured using a load of 7 gf / cm ２ A thickness gauge (measuring probe diameter 25 mm) is used.

[0089] The basis weight of the breathable film of the present disclosure is 10 g / m ２ ~40g / m ２ It is preferable that the thickness is 12 g / m ２ ~30g / m ２ More preferably, it is 15 g / m ２ ~25g / m ２ It is more preferable that the weight of the breathable film is 10 g / m ２If the basis weight of the breathable film is 40 g / m or more, the film tends to have excellent virus barrier properties. ２ If the moisture permeability is less than 100 mm, the moisture permeability tends to be excellent. The basis weight of the breathable film can be determined as follows. Three 100 mm x 100 mm square samples are taken from the measurement object, weighed, and the average weight is calculated. ２ This is converted into the weight per unit area and used as the basis weight of the breathable film.

[0090] In the breathable film of the present disclosure, the pore size distribution frequency (%) of pores having a specific pore size on the surface of the breathable film preferably satisfies the following (x1) or (x2), and more preferably satisfies (x1) and (x2). (x1): The total value of the pore size distribution frequency of pores having pore sizes of 3 μm to 5 μm is 3.0% or less, more preferably 2.7% or less. (x2): The total value of the pore size distribution frequency of pores having pore sizes of 1 μm to 3 μm is 7.5% or less, more preferably 7.1% or less, and even more preferably 6.8% or less.

[0091] In the present disclosure, the pore size distribution frequency (%) of pores on the surface of a breathable film can be measured by the following method. The obtained breathable film is cut into test pieces measuring approximately 25 mm square, and mercury intrusion porosimetry is performed using an Autopore V9620 pore size distribution analyzer manufactured by Micromeritics. Under conditions of an initial pressure of 7 kPa (approximately 1 psi, equivalent to a pore diameter of approximately 170 μm), the mercury parameters are set to the instrument's default mercury contact angle of 130 degrees and mercury surface tension of 485 dynes / cm. Using the output differential pore volume, the frequency for each pore size is calculated using the following formula: (differential pore volume) ÷ (integrated volume per 1 g of all pores) × 100. Rounding to one decimal place, the sum of the frequencies calculated above is calculated for the pore size ranges of 1.0 μm to 3.0 μm and 3.0 μm to 5.0 μm.

[0092] In the present disclosure, the breathable film of embodiment C has a pore size distribution frequency of pores having a pore size of 3 μm to 5 μm on the surface of the breathable film of 3.0% or less. A breathable film having a pore size distribution frequency in the above range has a virus barrier property of Class 5 or 6 protection level.

[0093] [Method for producing breathable film] The method for producing a breathable film of the present disclosure includes forming a resin composition containing a thermoplastic resin (preferably a polyolefin resin) and an inorganic filler into a film shape to obtain a film, and stretching the film in at least one axial direction.

[0094] In one embodiment, the method for producing a breathable film of the present disclosure uses an inorganic filler in which, in the particle size distribution of the inorganic filler, the particle size at which the cumulative 10% of the volume cumulative distribution is subtracted from the small particle size side is greater than 0.5 μm, and the particle size at which the cumulative 100% of the volume cumulative distribution is subtracted from the small particle size side is 8.0 μm or less.

[0095] In another aspect, in the method for producing a breathable film of the present disclosure, the inorganic filler used has a particle size distribution including a first peak having a maximum value A in the range of 1 μm or more and a second peak having a maximum value B in the range of less than 1 μm, and the maximum value A of the first peak is greater than the maximum value B of the second peak. In this case, the inorganic filler used has a particle size distribution including a first peak having a maximum value A in the range of 1 μm or more and a second peak having a maximum value B in the range of less than 1 μm, and the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.5 or more and less than 5.0.

[0096] In another aspect, the method for producing a breathable film of the present disclosure can produce a breathable film in which the total value of the pore size distribution frequency of pores having pore sizes of 3 μm to 5 μm on the surface of the breathable film is 3.0% or less, and the breathable film has a virus barrier property of a protection level of Class 5 or 6.

[0097] Details of the thermoplastic resin, inorganic filler, and other additives used in the method for producing a breathable film of the present disclosure, as well as details of the physical properties and performance of the breathable film produced by the method, are the same as those described for the breathable film of the present disclosure, and will not be described here.

[0098] The resin composition can be obtained by mixing a thermoplastic resin (preferably a polyolefin resin), an inorganic filler, and various additives, such as an antioxidant and a stretching aid, as needed. Examples of the mixing method include a dry blending method using a Henschel mixer, a tumbler mixer, or other mixer; a melt blending method using a single-screw extruder or a twin-screw extruder; and the like, and these methods may be used in combination. Examples of the method for molding the resin composition into a film include a film-forming method using a known molding machine, such as an extrusion molding machine equipped with a T-die or an inflation molding machine equipped with a circular die.

[0099] The breathable film of the present disclosure can be produced by uniaxially or biaxially stretching the obtained film to a predetermined thickness. The uniaxial stretching may be longitudinal uniaxial stretching or transverse uniaxial stretching. Note that, when simply referred to as uniaxial stretching, this means longitudinal uniaxial stretching. Furthermore, biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. Note that, when the film is laminated with a woven fabric, nonwoven fabric, or the like to form a fabric, longitudinal uniaxial stretching is preferred from the viewpoint of improving the mechanical strength of the breathable film. From the viewpoint of maintaining sufficient moisture permeability and mechanical strength, the stretching ratio is preferably about 1.2 to 10 times, and more preferably 2 to 5 times. Furthermore, after stretching, a heat setting treatment may be performed to stabilize the shape of the resulting pores.

[0100] [Fabric] The fabric of the present disclosure comprises the breathable film of the present disclosure. The fabric may be formed by laminating other materials, such as knitted fabrics, woven fabrics, nonwoven fabrics, films (including sheets), etc., to one or both sides of the breathable film. Examples of nonwoven fabrics include spunbond nonwoven fabrics, meltblown nonwoven fabrics, wet-laid nonwoven fabrics, spunlace nonwoven fabrics, dry-laid nonwoven fabrics, dry-laid pulp nonwoven fabrics, airlaid nonwoven fabrics, flash-spun nonwoven fabrics, open-fiber nonwoven fabrics, needle-punched nonwoven fabrics, and various known short-fiber nonwoven fabrics and long-fiber nonwoven fabrics (e.g., long-fiber cellulose nonwoven fabrics). One or more types may be combined. The method for laminating the breathable film of the present disclosure to other materials is not particularly limited. For example, various known methods can be used, including heat embossing, thermal fusion methods such as ultrasonic fusion, mechanical entanglement methods such as needle punching, methods using adhesives such as hot melt adhesives and urethane adhesives, and extrusion lamination.

[0101] [Protective Clothing] The protective clothing of the present disclosure includes the fabric of the present disclosure equipped with the breathable film of the present disclosure. Therefore, the protective clothing of the present disclosure has excellent virus barrier properties and moisture permeability. Furthermore, the breathable film of the present disclosure also has excellent mechanical strength and breathability.

[0102] [Other Applications] The breathable film of the present disclosure has excellent virus barrier properties and moisture permeability, and therefore can also be suitably used for medical sheets, medical supplies (gloves, hats, clothing, etc.), and non-medical protective sheets, protective articles, and the like.

[0103] EXAMPLES In order to more specifically explain the present invention, examples are given below, although the present invention is not limited to these examples.

[0104] The particle size distribution and specific surface area of ​​the inorganic fillers used in the examples and comparative examples were measured by the following methods.

[0105] (I) Particle size distribution of inorganic filler A laser diffraction / scattering particle size analyzer (MT3300II, LOW-WET, manufactured by Microtrac-Bell, measurement range: 0.02 μm to 2000 μm, number of channels: 138) was used as the measuring device to measure the particle size distribution of the inorganic filler. From the obtained particle size distribution, the positions of the first peak and the second peak; the frequency of the particle size distribution at the positions of the first peak and the second peak (i.e., maximum value A and maximum value B); and the particle sizes at cumulative 100%, cumulative 50%, cumulative 98%, and cumulative 10% were determined.

[0106] (II) Specific Surface Area of ​​Inorganic Filler The specific surface area of ​​the inorganic filler was measured using a specific surface area meter BELSOROP-max II manufactured by Microtrac-Bell Co., Ltd. In the example where the inorganic filler is a mixture of two types of calcium carbonate, the specific surface area of ​​the inorganic filler is the value for the mixture.

[0107] The basis weight, thickness, moisture permeability, virus barrier property, and pore size distribution frequency of the breathable films obtained in the examples and comparative examples were measured or evaluated by the following methods.

[0108] (1) Basis Weight Three 100 mm x 100 mm square samples were randomly taken from the breathable film, the weights were measured, and the average weight was calculated. ２ The weight was converted to a weight per unit, and was rounded to the nearest tenth.

[0109] (2) Thickness Five 5 mm x 5 mm square samples were randomly taken from the breathable film, and the thicknesses were measured and the average value was calculated. The values ​​were rounded to the nearest tenth. The thickness was measured under a load of 7 gf / cm. ２ A thickness gauge (measuring probe diameter 25 mm) was used.

[0110] (3) Moisture Permeability (Calcium Chloride Method) The moisture permeability (calcium chloride method) was determined by the method specified in JIS L1099:2012 A-1 (Calcium Chloride Method). Three evaluation samples with a diameter of approximately 70 mm were taken from the breathable film, and the moisture permeability per hour was measured at a temperature of 40°C and a relative humidity of 90%, and the average value was calculated. At this time, the value was rounded to the nearest whole number. Hereinafter, this may be referred to as moisture permeability method A.

[0111] (4) Virus Barrier Property Three evaluation samples measuring 100 mm x 100 mm were taken from the breathable film, and a virus barrier property test was carried out in accordance with Procedure B of JIS T8061:2015, 8.8 (Exposure of materials to bacteriophage load test suspension), and evaluation was carried out in accordance with JIS T8122:2015, 6.3.3 (Bacteriophage penetration resistance). Excellent virus barrier protection levels are Class 5 or 6, with Class 6 being the most excellent protection level.

[0112] (5) Pore Size Distribution Frequency of Breathable Film The obtained breathable film was cut into test pieces of approximately 25 mm square and measured by mercury intrusion porosimetry using a Micromeritics Autopore V9620 pore size distribution analyzer. Under conditions of an initial pressure of 7 kPa (approximately 1 psia, equivalent to a pore diameter of approximately 170 μm), the mercury parameters were set to the instrument's default mercury contact angle of 130 degrees and mercury surface tension of 485 dynes / cm. Using the output differential pore volume, the frequency for each pore size was calculated using the following formula: (Differential pore volume) ÷ (Volume per 1 g of all pores) × 100. Rounded to one decimal place, the sum of the frequencies calculated above was calculated for the pore size ranges of 1.0 μm to 3.0 μm and 3.0 μm to 5.0 μm.

[0113] The following raw materials were used in the examples and comparative examples. The inorganic filler (calcium carbonate) used in the examples and comparative examples was prepared as follows.

[0114] LLDPE-1: Evolue SP2040 (density: 0.913 g / cm ３ , MI: 3.8 g / 10 min. (According to ASTM D-1238, temperature 190 ° C, load 2.16 kg)) LDPE-1: Novatec LD LF128 (density: 0.922 g / cm ３ , MI: 0.25 g / 10 min. (According to ASTM D-1238, temperature 190 ° C, load 2.16 kg) PP-1: Prime Polypro F-704NP (density: 0.900 g / cm ３, MI: 7.0 g / 10 min. (According to ASTM D-1238, temperature 190°C, load 2.16 kg) Functional additive-1: 12-hydroxystearic acid triglyceride Functional additive-2: calcium stearate Antioxidant-1: hindered phenol-based antioxidant (Irganox)

[0115] Production Example 1: Heavy calcium carbonate JIS Class 17 (average particle size 2.1 μm) (hereinafter referred to as CC-A0) was mixed with purified water to a concentration of 60% by mass (hereinafter referred to as CC-B0), and a cationic dispersant (polyethyleneimine, molecular weight 10 kDa) was added in an amount of 1% by mass relative to CC-B0. The mixture was wet-pulverized using a bead mill (filling ratio of 170% of 1.2 mm diameter glass beads) and then passed through a 350-mesh screen to prepare an aqueous heavy calcium carbonate slurry. This aqueous slurry was centrifuged to remove coarse particles that had settled on the inner wall of the centrifuge, and then coarse particles were removed. The water content was adjusted to obtain an aqueous slurry (CC-B1) with a concentration of 50% by mass. Furthermore, 1% by mass of 12-hydroxyoctadecanoic acid was blended as a surface treatment agent in the form of an ethanol dispersion relative to the solid content of this aqueous slurry, and the mixture was thoroughly stirred and mixed. Furthermore, the slurry was allowed to stand and the supernatant was removed, and then the solvent was removed while stirring at 60°C under reduced pressure to prepare a calcium carbonate filler (CC-C1). The basic particle size properties of CC-C1 were a mode particle size of 1.9 μm, a mode particle size frequency of 9%, and a single peak.

[0116] <Production Example 2> An aqueous slurry (CC-B2) with a concentration of 50% was obtained in the same manner as in Production Example 1, except that the wet-grinding time was changed. Further, a surface treatment and the like were carried out in the same manner as in Production Example 1 to produce a calcium carbonate filler (CC-C2). The basic particle size properties of CC-C2 were a mode particle size of 0.6 μm, a mode particle size frequency of 9%, and a single peak.

[0117] <Production Example 3> CC-C1 from Production Example 1 and CC-C2 from Production Example 2 were mixed at a mass ratio of 2:1 to obtain CC-1. CC-1 had a particle size of 0.59 μm, a particle size of 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 1.48 μm, a particle size of 98% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 4.20 μm, and a particle size of 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, respectively. The basic particle size properties of CC-1 were a mode particle size (first peak) of 1.9 μm, a frequency of the mode particle size (maximum value A) of 6.4%, a maximum particle size (second peak) of 0.8 μm, a frequency of the maximum particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 3.7%, and a double peak. The maximum value A of CC-1 was larger than the maximum value B, and the ratio of maximum value A / maximum value B was 1.7. The specific surface area was 5.9 m ２ / g.

[0118] <Production Example 4> CC-B1 from Production Example 1 and CC-B2 from Production Example 2 were mixed at a mass ratio of 2:1, and further subjected to surface treatment and the like in the same manner as in Production Example 1, to produce a calcium carbonate filler (CC-2). CC-2 had a particle size of 0.59 μm, corresponding to 10% of the cumulative volume when the cumulative volume distribution was subtracted from the small particle size side in the particle size distribution, a particle size of 1.48 μm, corresponding to 50% of the cumulative volume when the cumulative volume distribution was subtracted from the small particle size side in the particle size distribution, a particle size of 4.20 μm, and a particle size of 100% of the cumulative volume when the cumulative volume distribution was subtracted from the small particle size side in the particle size distribution, respectively. The basic particle size properties of CC-2 were a mode particle size (first peak) of 1.9 μm, a frequency of the mode particle size (maximum value A) of 6.4%, a maximum particle size (second peak) of 0.8 μm, a frequency of the maximum particle size (frequency of particle size distribution at the position of the second peak: maximum value B) of 3.7%, and a double peak. The maximum value A of CC-2 was larger than the maximum value B, and the ratio of maximum value A / maximum value B was 1.7. The specific surface area was 5.9 m ２ / g.

[0119] <Production Example 5> Purified water was added to heavy calcium carbonate CC-A0 to a concentration of 60% by mass, followed by wet-pulverization using a bead mill (filling ratio of 170% glass beads with a diameter of 1.2 mm). The mixture was then passed through a 350-mesh screen to prepare an aqueous heavy calcium carbonate slurry. This aqueous slurry was centrifuged to remove coarse particles that had settled on the inner wall of the centrifuge, and then coarse particles were removed. The moisture content was then adjusted to obtain an aqueous slurry with a concentration of 50% by mass. Furthermore, 1% by mass of stearic acid was blended as a surface treatment agent in the form of an ethanol dispersion relative to the solid content of this aqueous slurry, and the mixture was thoroughly stirred and mixed. The slurry was then allowed to stand, the supernatant was removed, and the solvent was then removed while stirring at 60°C under reduced pressure to produce a calcium carbonate filler (CC-3). In the particle size distribution of CC-3, the particle size at 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side was 1.16 μm, the particle size at 50% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side was 2.12 μm, the particle size at 98% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side was 4.63 μm, and the particle size at 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side was 6.54 μm. The basic particle size properties of CC-3 were a mode particle size of 2.1 μm, a frequency of the mode particle size of 9.0%, and a single peak. The specific surface area was 1.8 m ２ / g.

[0120] <Production Example 6> Heavy calcium carbonate BF100 (manufactured by Bihoku Funka Kogyo Co., Ltd.) was pulverized using an impact pulverizer and classified by dry classification. 2% by mass of stearic acid was added relative to the mass of calcium carbonate to form an ethanol dispersion, which was thoroughly stirred and mixed. Furthermore, the solvent was removed from the slurry under reduced pressure at 60°C to produce CC-4. CC-4 had a particle size of 0.75 μm, which corresponds to 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution; a particle size of 2.12 μm, which corresponds to 50% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution; a particle size of 7.13 μm, which corresponds to 98% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution; and a particle size of 11.00 μm, which corresponds to 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution. The basic particle size properties of CC-4 were a mode particle size of 2.3 μm, a mode particle frequency of 6.0%, and a single peak. The specific surface area was 5.9 m ２ / g.

[0121] Production Example 7 A calcium carbonate filler (CC-C3) was produced in the same manner as in Production Example 1, except that the wet-grinding time was changed. The basic particle size properties of CC-C3 were a mode particle size of 0.6 μm, a mode particle size frequency of 9%, and a single peak.

[0122] <Production Example 8> A calcium carbonate filler (CC-C4) was produced in the same manner as in Production Example 1, except that the wet-grinding time was changed. The basic particle size properties of CC-C4 were a mode particle size of 1.6 μm, a mode particle size frequency of 9%, and a single peak.

[0123] <Production Example 9> CC-C3 from Production Example 7 and CC-C4 from Production Example 8 were mixed at a mass ratio of 3:2 to obtain CC-5. CC-5 had a particle size of 0.49 μm, a particle size of 50% of the cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 2.75 μm, and a particle size of 100% of the cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 0.89 μm, a particle size of 98% of the cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, and a particle size of 3.89 μm. The basic particle size properties of CC-5 were a mode particle size (second peak) of 0.63 μm, a frequency of the mode particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 6.5%, a maximum particle size (first peak) of 1.50 μm, a frequency of the maximum particle size (maximum value A) of 4.6%, and a double peak. The maximum value A of CC-5 was smaller than the maximum value B, and the ratio of maximum value A / maximum value B was 0.7. The specific surface area was 8.1 m ２ / g.

[0124] <Production Example 10> A calcium carbonate filler (CC-6) was produced in the same manner as in Production Example 1, except that the wet-milling time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. CC-6 had a particle size of 1.10 μm, a particle size of 10% cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 1.97 μm, a particle size of 98% cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 4.40 μm, and a particle size of 100% cumulative volume when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 6.27 μm. The basic particle size properties of CC-6 were a mode particle size of 2.0 μm, a mode particle size frequency of 8.8%, and a single peak.

[0125] Production Example 11 A calcium carbonate filler (CC-C5) was produced in the same manner as Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. The basic particle size properties of CC-C5 were a mode particle size of 0.7 μm, a mode particle size frequency of 9%, and a single peak.

[0126] Production Example 12 A calcium carbonate filler (CC-C6) was produced in the same manner as Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to stearic acid. The basic particle size properties of CC-C6 were a mode particle size of 1.8 μm, a mode particle size frequency of 9%, and a single peak.

[0127] Production Example 13 CC-7 was produced in the same manner as in Production Example 3, except that CC-C5 from Production Example 11 and CC-C6 from Production Example 12 were mixed at a mass ratio of 1:5. CC-7 had a particle size of 0.62 μm, a particle size of 10% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 1.70 μm, a particle size of 98% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, and a particle size of 8.25 μm, a particle size of 100% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution. The basic particle size properties of CC-7 were a mode particle size (first peak) of 1.8 μm, a frequency of the mode particle size (maximum value A) of 8.2%, a maximum particle size (second peak) of 0.8 μm, a frequency of the maximum particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 1.6%, and a double peak. The maximum value A of CC-7 was larger than the maximum value B, and the ratio of maximum value A / maximum value B was 5.1. The specific surface area was 5.2 m ２ / g.

[0128] Production Example 14 CC-8 was produced in the same manner as in Production Example 3, except that CC-C5 from Production Example 11 and CC-C6 from Production Example 12 were mixed at a mass ratio of 5:4. CC-8 had a particle size of 0.55 μm, a particle size of 10% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 1.54 μm, a particle size of 98% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 6.80 μm, and a particle size of 100% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 8.25 μm. The basic particle size properties of CC-8 were a mode particle size (first peak) of 1.7 μm, a frequency of the mode particle size (maximum value A) of 4.9%, a maximum particle size (second peak) of 0.70 μm, a frequency of the maximum particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 5.8%, and a double peak. The maximum value A of CC-8 was smaller than the maximum value B, and the ratio of maximum value A / maximum value B was 0.8. The specific surface area was 7.6 m ２ / g.

[0129] Production Example 15 A calcium carbonate filler (CC-C7) was produced in the same manner as Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. The basic particle size properties of CC-C7 were a mode particle size of 1.2 μm, a mode particle size frequency of 9%, and a single peak.

[0130] Production Example 16 A calcium carbonate filler (CC-C8) was produced in the same manner as Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. The basic particle size properties of CC-C8 were a mode particle size of 1.7 μm, a mode particle size frequency of 9%, and a single peak.

[0131] Production Example 17 CC-9 was produced in the same manner as in Production Example 3, except that CC-C5 from Production Example 15 and CC-C6 from Production Example 16 were mixed at a mass ratio of 2:3. CC-9 had a particle size of 0.60 μm, a particle size of 10% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 1.40 μm, a particle size of 98% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution, a particle size of 7.52 μm, and a particle size of 100% cumulative when subtracting the volume cumulative distribution from the small particle size side in the particle size distribution. The basic particle size properties of CC-9 were a mode particle size (first peak) of 1.6 μm, a frequency of the mode particle size (maximum value A) of 7.0%, a maximum particle size (second peak) of 1.2 μm, a frequency of the maximum particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 4.9%, and a double peak. The maximum value A of CC-9 was larger than the maximum value B, and the ratio of maximum value A / maximum value B was 1.4. The specific surface area was 6.0 m ２ / g.

[0132] Production Example 18 A calcium carbonate filler (CC-C9) was produced in the same manner as in Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. The basic particle size properties of CC-C9 were a mode particle size of 0.5 μm, a mode particle size frequency of 9%, and a single peak.

[0133] Production Example 19 A calcium carbonate filler (CC-C10) was produced in the same manner as Production Example 1, except that the wet-grinding time was changed and the surface treatment agent was changed to 1% by mass of stearic acid. The basic particle size properties of CC-C10 were a mode particle size of 1.0 μm, a mode particle size frequency of 9%, and a single peak.

[0134] Production Example 20 CC-10 was produced in the same manner as in Production Example 3, except that CC-C9 of Production Example 19 and CC-C10 of Production Example 19 were mixed at a mass ratio of 3:4. CC-10 had a particle size of 0.25 μm, a particle size of 0.82 μm, a particle size of 0.82 μm, a particle size of 0.82 μm, a particle size of 4.10 μm, and a particle size of 5.10 μm, a particle size of 50% when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 4.10 μm, and a particle size of 5.10 μm, a particle size of 50% when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution, a particle size of 4.10 μm, and a particle size of 5.10 μm, a particle size of 50% when subtracting the cumulative volume distribution from the small particle size side in the particle size distribution. The basic particle size properties of CC-10 were a mode particle size (first peak) of 1.0 μm, a frequency of the mode particle size (maximum value A) of 7.10%, a maximum particle size (second peak) of 0.5 μm, a frequency of the maximum particle size (frequency of the particle size distribution at the position of the second peak: maximum value B) of 5.5%, and a double peak. The maximum value A of CC-10 was larger than the maximum value B, and the ratio of maximum value A / maximum value B was 1.3. The specific surface area was 8.5 m ２ / g.

[0135] Example 1 36.3% by mass of LLDPE-1, 2.0% by mass of LDPE-1, 2.9% by mass of PP-1, 56.8% by mass of CC-1, 1.4% by mass of functional additive-1, 0.5% by mass of functional additive-2, and 0.2% by mass of antioxidant-1 were mixed in a tumbler mixer, and then uniformly kneaded at 230°C using a tandem kneading extruder to form pellets of a resin composition. The composition of Example 1 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to the nearest tenth. The pellets were molded into a film using a uniaxially stretching T-die film molding machine equipped with a roll stretching machine. At this time, the die temperature was set to 230°C, the preheat roll temperature was set to 70°C, and the film was uniaxially stretched in the MD direction at a stretch ratio of 3.5 times between the preheat roll and the stretch roll, and then heat-set at 90°C to obtain a breathable film A. The breathable film A had a basis weight of 20.2 g / m ２ , thickness 24.6 μm, moisture permeability A method 410 g / (m ２The results of the virus barrier evaluation were excellent, with a grade of Class 6. The pore size distribution frequency was 6.44% (total of 1 μm to 3 μm) and 2.42% (total of 3 μm to 5 μm). The physical properties of breathable film A are summarized in Table 3.

[0136] [Example 2] Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-2, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 34.3% by mass, 2.0% by mass, 2.9% by mass, 58.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Example 2 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures have been rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. As a result, a breathable film B was obtained. The physical properties of Breathable Film B are summarized in Table 3.

[0137] [Example 3] Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-6, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Example 3 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures have been rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. As a result, a breathable film C was obtained. The physical properties of the breathable film C are summarized in Table 3.

[0138] Example 4 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-3, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Example 1 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures have been rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. As a result, a breathable film D was obtained. The physical properties of Breathable Film D are summarized in Table 3.

[0139] Comparative Example 1 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the contents of LLDPE-1 were 36.3% by mass, LDPE-1 were 2.0% by mass, PP-1 were 2.9% by mass, CC-4 was 56.8% by mass, functional additive-1 was 1.4% by mass, functional additive-2 was 0.5% by mass, and antioxidant-1 was 0.2% by mass, and the stretching ratio was 3.0 times. The composition of Comparative Example 1 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to one decimal place. Furthermore, film molding was performed in the same manner as in Example 1, except that the stretching ratio was 3.0 times. As a result, breathable film a was obtained. The physical properties of breathable film a are summarized in Table 3. Breathable film b had excellent moisture permeability but virus barrier property of Class 3.

[0140] Comparative Example 2 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-5, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Comparative Example 2 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures have been rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. Breathable film b was thus obtained. The physical properties of breathable film b are summarized in Table 3. Breathable film b had excellent moisture permeability but a virus barrier property of Class 4.

[0141] Comparative Example 3 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-7, functional additive-1, and antioxidant-2 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Comparative Example 3 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to the nearest tenth. Film molding was then performed in the same manner as in Example 1. Breathable film c was thus obtained. The physical properties of breathable film c are summarized in Table 3. Breathable film c had excellent moisture permeability but a virus barrier property of Class 4.

[0142] Comparative Example 4 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-8, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Comparative Example 4 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. Breathable film d was thus obtained. The physical properties of breathable film d are summarized in Table 3. Breathable film d had excellent moisture permeability but a virus barrier property of Class 4.

[0143] Comparative Example 5 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-9, Functional Additive-1, Functional Additive-2, and Antioxidant-1 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Comparative Example 5 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. Breathable Film e was thus obtained. The physical properties of Breathable Film e are summarized in Table 3. Breathable Film e had excellent moisture permeability, but its virus barrier property was Class 4.

[0144] Comparative Example 6 Pellets of a resin composition were prepared in the same manner as in Example 1, except that the amounts of LLDPE-1, LDPE-1, PP-1, CC-10, functional additive-1, and antioxidant-2 were changed to 36.3% by mass, 2.0% by mass, 2.9% by mass, 56.8% by mass, 1.4% by mass, 0.5% by mass, and 0.2% by mass, respectively. The composition of Comparative Example 6 is shown in Table 1. Note that the total amount of each component does not equal 100% by mass because the figures are rounded to the nearest tenth. Further, film molding was performed in the same manner as in Example 1. Breathable film f was thus obtained. The physical properties of breathable film f are summarized in Table 3. Breathable film f had excellent moisture permeability but a virus barrier property of Class 4.

[0145]

[0146]

[0147]

[0148] The disclosure of Japanese Patent Application No. 2023-214295, filed on December 19, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A breathable film containing a thermoplastic resin and an inorganic filler, wherein the particle size distribution of the inorganic filler has a particle size that is greater than 0.5 μm and represents 10% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side, and a particle size that is 8.0 μm or less and represents 100% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side.

2. The breathable film according to claim 1, wherein in the particle size distribution of the inorganic filler, the particle size at 50% of the cumulative volume distribution when subtracting the cumulative volume distribution from the small particle size side is greater than 1.0 μm.

3. The breathable film according to claim 1, wherein the particle size distribution of the inorganic filler includes a first peak having a maximum value A in the range of 1 μm or more.

4. The breathable film according to claim 3, wherein the frequency of the particle size distribution at the position of the first peak is 10% or less.

5. The breathable film according to claim 3, wherein the inorganic filler further comprises a second peak having a maximum value B in the range of less than 1 μm.

6. The breathable film according to claim 5, wherein the ratio of the maximum value A of the first peak to the maximum value B of the second peak (maximum value A / maximum value B) is 1.0 or more and less than 5.

0.

7. The breathable film according to claim 1, wherein the content of the inorganic filler is 40% by mass to 70% by mass.

8. The breathable film according to claim 1, wherein the inorganic filler is at least one selected from the group consisting of calcium sulfate, calcium carbonate, and barium sulfate.

9. The breathable film of claim 1, wherein the breathable film has a virus barrier property of Class 5 or 6 protection level.

10. A fabric comprising the breathable film according to any one of claims 1 to 9 and a nonwoven fabric selected from the group consisting of a spunbond nonwoven fabric, a meltblown nonwoven fabric, a wet-laid nonwoven fabric, a spunlace nonwoven fabric, a dry-laid nonwoven fabric, a dry pulp nonwoven fabric, an airlaid nonwoven fabric, a flash-spun nonwoven fabric, an open-fiber nonwoven fabric, and a needle-punched nonwoven fabric.

11. Protective clothing comprising the fabric of claim 10.

12. A method for producing a breathable film, comprising: forming a resin composition containing a thermoplastic resin and an inorganic filler into a film to obtain a film; and stretching the film in at least one axial direction, wherein the inorganic filler has a particle size distribution in which the particle size at which the cumulative 10% of the volumetric distribution is obtained when subtracting the cumulative volume distribution from the small particle size side is greater than 0.5 μm, and the particle size at which the cumulative 100% of the volumetric distribution is obtained when subtracting the cumulative volume distribution from the small particle size side is 8.0 μm or less.

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