Resin film and method for producing same

Abstract

[Problem] To provide a resin film which does not contain fluorine, has not only acoustic performance (sound transmission properties) and air permeability, but also high water repellency and oil repellency, and is suitable for a sound-transmitting waterproof film.　[Solution] This resin film is obtained by curing an ultraviolet curable acrylic resin composition that contains silane-modified inorganic particles having a primary particle diameter of 10-200 nm, wherein, if the average value of heights of recesses and projections obtained on the basis of a cross-sectional shape of the resin film surface obtained from a surface image including height information captured by means of a laser microscope is used as a reference value, the surface has recesses and projections within ±2,500 nm from the reference value, and the air permeability as determined by JIS L1096 B method (Gurley method) is 10-300 seconds / 100 mL.　

Description

Resin film and its manufacturing method

[0001] The present invention relates to a porous resin film made of a cured ultraviolet-curable acrylic resin containing silane-modified inorganic particles, and a method for producing the same. More specifically, the present invention relates to a resin film that does not contain fluorine and can be used as a sound-permeable waterproofing film that has high water and oil repellency as well as acoustic performance (sound permeability) and breathability, and a method for producing the same.

[0002] Electrical and electronic products such as mobile phones, smartphones, smartwatches, cordless phones, portable media players, portable game consoles, digital cameras, digital video cameras, and earphones have sound receiving and sound generating units such as microphones and speakers in their housing structures, and openings are provided in the corresponding positions of these units, through which sound is transmitted.

[0003] Since these electrical appliances are often used in wet environments, it is desirable for them to have a waterproof structure. Conventionally, waterproof sound-transmitting members that prevent water from entering the housing and have low acoustic loss are attached to the openings in the sound-emitting unit and sound-receiving unit. The waterproof sound-transmitting member has a sound-transmitting waterproof membrane.

[0004] Porous membranes made of urethane resin or fluororesin are generally used as sound-permeable waterproofing membranes. The properties required for sound-permeable waterproofing membranes include not only acoustic performance (sound permeability), but also breathability and water and oil repellency. In recent years, the use of porous membranes made of fluorine (PTFE) has become mainstream to enhance water and oil repellency, but as PFAS regulations have led to a trend toward non-fluorinated materials, there is a demand for the development of sound-permeable waterproofing membranes that do not contain fluorine and have high water and oil repellency.

[0005] Patent Document 1 discloses a polymer matrix composite comprising functional particles and a polymer network structure, and has a porosity of less than 90%. The pores are formed by phase separation, and the polymer matrix composite has breathability, but there is no disclosure regarding water repellency or oil repellency.

[0006] Patent Document 2 describes a method for producing a porous body having a pore size of 1 μm or less by inducing phase separation using an ultraviolet curable resin, but does not disclose any water repellency or oil repellency.

[0007] JP 2021-503530 A JP 2007-269912 A

[0008] The present invention has been made in view of the current situation, and aims to provide a resin film that does not contain fluorine and can be suitably used as a sound-permeable waterproofing film that has not only acoustic performance (sound permeability) and breathability but also high water and oil repellency.

[0009] That is, the present invention relates to the following resin film and a method for producing the same: (1) A resin film composed of an ultraviolet-curable acrylic resin cured product containing silane-modified inorganic particles with a primary particle diameter of 10 to 200 nm, wherein the surface of the resin film has irregularities within ±2,500 nm of a reference value, where the reference value is an average value of the height of irregularities determined based on a cross-sectional shape obtained from an image of the surface, including height information, photographed with a laser microscope, and the resin film has an air permeability of 10 to 300 seconds / 100 mL according to JIS L1096 Method B (Gurley method).

[0010] (2) The resin film according to (1), having a film thickness of 1 to 100 μm. (3) The resin film according to (1), having a content of the silane-modified inorganic particles of 1 to 50 mass% relative to the total amount of the ultraviolet-curable acrylic resin cured product.

[0011] (4) A method for producing the resin film according to (1), comprising the following steps A to D: Step A: forming a film made of an ultraviolet-curable acrylic resin composition solution containing at least an ultraviolet-curable acrylic oligomer, an ultraviolet-curable monomer, silane-modified inorganic particles having a primary particle size of 10 to 200 nm, a photopolymerization initiator, and a solvent on a release material; Step B: irradiating the film obtained in Step A with ultraviolet light to temporarily cure it, thereby forming a temporarily cured film having a phase-separated structure; Step C: heat-treating the temporarily cured film obtained in Step B; and Step D: after Step C, irradiating the temporarily cured film with ultraviolet light to permanently cure it.

[0012] According to the present invention, it is possible to obtain a porous resin film that does not contain fluorine, has excellent sound permeability and air permeability, and has high water and oil repellency, and can be used as a sound-permeable waterproof film.

[0013] 1 is a micrograph showing a surface image obtained by photographing the surface of the resin film produced in Example 1 with a laser microscope. 2 is a graph showing a cross-sectional curve obtained from a surface image of the resin film produced in Example 1 with a laser microscope. 3 is a cross-sectional photograph of the resin film produced in Example 1, taken with a field emission scanning electron microscope (FE-SEM; 30,000x magnification). 4 is a cross-sectional photograph of the resin film produced in Comparative Example 1, taken with a field emission scanning electron microscope (FE-SEM; 30,000x magnification). 5 is a cross-sectional photograph of the resin film produced in Comparative Example 3, taken with a field emission scanning electron microscope (FE-SEM; 30,000x magnification).

[0014] 1. Resin Film The resin film of the present invention is composed of an ultraviolet (UV) curable acrylic resin cured product containing at least silane-modified inorganic particles having a primary particle diameter of 10 to 200 nm.

[0015] (1) UV-Curable Acrylic Resin Cured Product The UV-curable acrylic resin cured product constituting the resin film of the present invention is obtained by treating with UV light an UV-curable acrylic resin composition containing at least a UV-curable acrylic oligomer and silane-modified inorganic particles having a primary particle diameter of 10 to 200 nm, and curing the composition.

[0016] The ultraviolet-curable acrylic resin composition may contain, as necessary, an ultraviolet-curable monomer, a photopolymerization initiator, a thiol, etc., in addition to the ultraviolet-curable acrylic oligomer and the silane-modified inorganic particles. The ultraviolet-curable acrylic resin composition may also contain a solvent for the resin film-forming step. Hereinafter, the ultraviolet-curable acrylic resin composition containing a solvent will be referred to as an "ultraviolet-curable acrylic resin composition solution."

[0017] <Ultraviolet-Curable Acrylic Oligomer> Examples of the ultraviolet-curable acrylic oligomer of the present invention include (meth)acrylate oligomers such as urethane-based, acrylic-based, polycarbonate-based, epoxy-based, polyether-based, polyester-based, and silicone-based oligomers. These compounds can be used alone or in combination of two or more.

[0018] Examples of the urethane-based (meth)acrylate oligomer include urethane (meth)acrylate obtained by reacting a polyol (meth)acrylate having at least one hydroxyl group in the molecule with a diisocyanate compound or a triisocyanate compound, and tris(2-hydroxyethyl)isocyanurate (meth)acrylate obtained by reacting tris(2-hydroxyethyl)isocyanuric acid with (meth)acrylic acid or a (meth)acrylic acid ester.

[0019] Examples of the (meth)acrylic oligomer include polymers of alkyl (meth)acrylates such as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate; and copolymers of the above monomers with compounds selected from vinyl carboxylic acid compounds such as maleic acid, itaconic acid, crotonic acid, and fumaric acid; glycidyl group-containing vinyl compounds such as glycidyl (meth)acrylate, allyl glycidyl ether, ethyl glycidyl acrylate, crotonyl glycidyl ether, and glycidyl crotonate; hydroxyethyl (meth)acrylate, vinyl acetate, (meth)acrylonitrile, (meth)acrylic acid chloride, and N-(meth)acryloylmorpholine.

[0020] Examples of polycarbonate-based (meth)acrylate oligomers include oligomers obtained by reacting polycarbonate polyol, polyisocyanate, and hydroxy-functional ethylenically unsaturated monomers.

[0021] Examples of epoxy (meth)acrylate oligomers include epoxy (meth)acrylates obtained by reacting epoxy resins with (meth)acrylic acid.

[0022] Examples of polyether-based (meth)acrylate oligomers include polyol (meth)acrylates in which at least one hydroxyl group of a polyhydric alcohol such as polyethylene glycol, polypropylene glycol, glycerin, trimethylolpropane, pentaerythritol, ditrimethylolpropane, or dipentaerythritol is replaced with a (meth)acryloyloxy group.

[0023] Examples of polyester-based (meth)acrylate oligomers include esters of (meth)acrylic acid and polyester diols composed of adipic acid and 1,6-hexanediol.

[0024] Examples of silicone-based (meth)acrylate oligomers include silicone oligomers in which the reactive functional group is an alkoxysilyl group (Si—OR).

[0025] Among these, it is preferable to use a bifunctional urethane (meth)acrylate oligomer having a urethane bond and a (meth)acrylic group in the molecule as the ultraviolet-curable acrylic oligomer of the present invention, because the coating film obtained after curing has excellent flexibility.

[0026] The urethane (meth)acrylate oligomer is usually obtained by reacting an isocyanate compound, a polyol compound, and a hydroxyl group-containing (meth)acrylic monomer, and there are various types such as polyester-based, polycarbonate-based, and polyether-based, depending on the polyol compound used.

[0027] The average molecular weight of the urethane (meth)acrylate oligomer is not particularly limited, but the weight average molecular weight (Mw) is preferably 1,000 to 20,000, more preferably 3,000 to 10,000.

[0028] The content of the ultraviolet-curable acrylic oligomer is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 12% by mass or more, and particularly preferably 15% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition. The upper limit of the content is not particularly limited, but is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and particularly preferably 20% by mass or less.

[0029] The content of the ultraviolet-curable acrylic oligomer is preferably 3% by mass or more, more preferably 5% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution including the solvent. The upper limit of the content is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less.

[0030] <Ultraviolet-Curable Monomer> The ultraviolet-curable acrylic resin composition of the present invention preferably contains an ultraviolet-curable monomer. Examples of the ultraviolet-curable monomer include acrylate-based compounds, ether-based compounds, ester-based compounds, and urethane-based compounds. These ultraviolet-curable monomers can be used alone or in combination of two or more.

[0031] Examples of the acrylate-based compound include (meth)acrylic acid esters of polyhydric alcohols and hydroxyl acids. Examples of the acrylate-based compound include phenoxy polyethylene glycol (meth)acrylate, epoxy (meth)acrylate, oligoester (meth)acrylate, urethane (meth)acrylate, hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, t-butyl (meth)acrylate, and dipentaerythritol hexa(meth)acrylate. Cyclopolymerizable monomers such as methyl 2-[(allyloxy)methyl]acrylate can also be used. Commercially available cyclopolymerizable monomers such as those under the trade name "AOMA" (manufactured by Nippon Shokubai Co., Ltd.) can also be used.

[0032] Examples of the ether-based compounds include alkylene glycol-based compounds such as alkylene glycol and polyalkylene glycol, and blocked compounds in which one or both ends of these compounds are blocked with an alkyl group, an alkenyl group, an aryl group, an acyl group, or a combination thereof, such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and blocked compounds in which one or both ends of these compounds are blocked with an alkyl group such as a methyl group, an alkenyl group such as an allyl group, an aryl group such as a phenyl group, an acyl group such as an acetyl group or a (meth)acryloyl group, or a combination thereof.

[0033] Examples of the ester-based compound include polyester oligomers such as ε-caprolactone (meth)acrylate and polycaprolactone oligomer, and blocked compounds in which one or both ends of these are blocked with an alkyl group such as a methyl group, an alkenyl group such as an allyl group, an aryl group such as a phenyl group, an acyl group such as an acetyl group or a (meth)acryloyl group, or a combination thereof.

[0034] Examples of the urethane-based compound include reaction products of hydroxy(meth)acrylate-based compounds such as hydroxyethyl(meth)acrylate and glycerin dimethacrylate, compounds having an isocyanate group such as methylene diisocyanate, and polyols (e.g., polyester polyol, polyether polyol, etc.).

[0035] The content of the ultraviolet-curable monomer is preferably 25% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition. The upper limit of the content is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0036] The content of the ultraviolet-curable monomer is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution including the solvent. The upper limit of the content is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0037] More preferred examples of the ultraviolet-curable monomer include a cyclopolymerizable monomer and / or a combination of one or more monomers containing t-butyl acrylate, and particularly preferred examples include a combination of one or more monomers containing t-butyl acrylate.

[0038] When t-butyl acrylate is used in combination with other ultraviolet-curable monomers, the content of the t-butyl acrylate is preferably 3% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, based on the total amount of the ultraviolet-curable monomers. There is no particular upper limit to the content, but it is preferably 50% by mass or less, more preferably 30% by mass or less.

[0039] The content of t-butyl acrylate is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition. The upper limit of the content is not particularly limited, but is preferably 25% by mass or less, and more preferably 20% by mass or less.

[0040] The t-butyl acrylate content is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution. The upper limit of the content is not particularly limited, but is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 7% by mass or less.

[0041] <Thiol Compound> The ultraviolet-curable acrylic resin composition of the present invention may contain a thiol compound as needed. The thiol compound is not particularly limited, and a conventionally known primary thiol or secondary thiol can be used, but a secondary thiol is more preferably used in that the reactivity of the ultraviolet-curable resin composition is not too high.

[0042] More preferably, the secondary thiol is a trifunctional or tetrafunctional secondary thiol selected from the group consisting of pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropane tris(3-mercaptobutyrate), and 1,3,5-tris[2-(3-mercaptobutanoyloxy)ethyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. These may be used alone or in combination of two or more.

[0043] The content of the thiol compound is not particularly limited, but is preferably 3% by mass or more, more preferably 5% by mass or more, and particularly preferably 7% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition. The upper limit of the content is not particularly limited, but is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[0044] The content of the thiol compound is preferably 1% by mass or more, more preferably 2% by mass or more, and particularly preferably 2.5% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution including the solvent. The upper limit of the content is not particularly limited, but is preferably 10% by mass or less, more preferably 7% by mass or less, and particularly preferably 5% by mass or less.

[0045] <Photopolymerization initiator> The ultraviolet-curable acrylic resin composition of the present invention preferably contains a photopolymerization initiator in order to appropriately cure the composition by ultraviolet light. The photopolymerization initiator is not particularly limited, but examples thereof include a photocationic polymerization initiator and a radical polymerization initiator. Furthermore, it is preferable to use a photocationic polymerization initiator and a radical polymerization initiator in combination.

[0046] Examples of the radical polymerization initiator include alkylphenone compounds, benzophenone compounds, benzoin compounds, thioxanthone compounds, halomethylated triazine compounds, halomethylated oxadiazole compounds, biimidazole compounds, oxime ester compounds, titanocene compounds, benzoate ester compounds, acridine compounds, and azo compounds.

[0047] As the photocationic polymerization initiator, any known and commonly used initiator that generates a Bronsted acid upon irradiation with ultraviolet light and can polymerize a polymerizable compound can be used. Examples of such photocationic polymerization initiators include an aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, etc. as the cationic moiety and BF as the anionic moiety. ４ － , P.F. ６ － , SbF ６ － , [BX ４ ] － (wherein X is a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), etc.

[0048] Examples of alkylphenone compounds include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone.

[0049] Examples of the benzophenone compounds include benzophenone, 4,4'-bis(dimethylamino)benzophenone, and 2-carboxybenzophenone.

[0050] Examples of the benzoin compounds include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

[0051] Examples of thioxanthone compounds include thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone.

[0052] Examples of halomethylated triazine compounds include 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-sec-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-sec-triazine, 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-sec-triazine, and 2-(4-ethoxycarboxynylnaphthyl)-4,6-bis(trichloromethyl)-sec-triazine.

[0053] Examples of halomethylated oxadiazole compounds include 2-trichloromethyl-5-[β-(2'-benzofuryl)vinyl]-1,3,4-oxadiazole, 2-trichloromethyl-5-[β-(2'-(6"-benzofuryl)vinyl)]-1,3,4-oxadiazole, and 2-trichloromethyl-5-furyl-1,3,4-oxadiazole.

[0054] Examples of biimidazole compounds include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, and 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0055] Examples of the oxime ester compounds include 1-[4-(phenylthio)-2-(O-benzoyloxime)]-1,2-octanedione and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime)ethanone.

[0056] Examples of titanocene compounds include bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium.

[0057] Examples of the benzoate ester compounds include p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid, etc. Examples of the acridine compounds include 9-phenylacridine, etc.

[0058] Examples of the azo compounds include 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2-methylpropionate) dimethyl.

[0059] A preferred onium salt is an onium salt in which the anion moiety is tetrakis(pentafluorophenyl)borate (TFPB) and the cation moiety is a triarylsulfonium, which is an aromatic sulfonium. Specific examples of commercially available onium salts in which TFPB is the anion include those under the trade names "IRGACURE 270" (manufactured by BASF Japan Ltd.), "IRGACURE 290" (manufactured by BASF Japan Ltd.), and "WPI-124" (manufactured by Wako Pure Chemical Industries, Ltd.).

[0060] These photopolymerization initiators may be used alone or in combination of two or more. The content of the photopolymerization initiator is not particularly limited, but is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, in the ultraviolet-curable acrylic resin composition solution. The upper limit of the content of the photopolymerization initiator is not particularly limited, but is preferably 15% by mass or less, more preferably 12% by mass or less, even more preferably 7% by mass or less, and particularly preferably 3% by mass or less, in the ultraviolet-curable acrylic resin composition solution. If the content of the photopolymerization initiator is within the above range, the ultraviolet-curable acrylic resin composition tends to be appropriately cured by ultraviolet light.

[0061] Furthermore, as the photopolymerization initiator, it is preferable to use a combination of a radical polymerization initiator and a photocationic polymerization initiator. When used in combination, the content ratio of the photocationic polymerization initiator to the total amount of the photopolymerization initiator is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. The upper limit of the content of the photocationic polymerization initiator in the photopolymerization initiator is not particularly limited, but is preferably 100% by mass or less, more preferably 80% by mass or less, even more preferably 50% by mass or less, and particularly preferably 40% by mass or less.

[0062] When the content of the photocationic polymerization initiator is within the above range, appropriate foaming is induced in the provisionally cured film after provisional irradiation with ultraviolet light, and appropriate pores tend to be generated in the resin film of the present invention obtained through the heat treatment step and the main curing step, making it easier to obtain good breathability.

[0063] <Solvent> In the resin film forming step, an appropriate solvent is blended with the ultraviolet-curable acrylic resin composition as needed, and the composition is used as an ultraviolet-curable acrylic resin composition solution. The solvent is not particularly limited, but water or an organic solvent is used. Preferably, an organic solvent is blended as a liquid component capable of dissolving the ultraviolet-curable acrylic oligomer.

[0064] The type of organic solvent is not particularly limited, but examples thereof include aromatic hydrocarbon solvents such as xylene and toluene; alcohol solvents such as methanol, ethanol, isopropyl alcohol, and 1-hexanol; ketone solvents such as methyl ethyl ketone; glycol ether solvents, acetate solvents, ester solvents, hydrocarbon solvents, and fatty acid ester solvents. These organic solvents can also be used in combination as appropriate.

[0065] The content of the solvent is not particularly limited, but is preferably 30% by mass or more, more preferably 40% by mass or more, and particularly preferably 50% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution containing the solvent. The upper limit of the content is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less. If the amount of the solvent used is within the above range, uneven coating and uneven thickness can be prevented.

[0066] <Optional Components> The ultraviolet-curable acrylic resin composition of the present invention may contain, in addition to the ultraviolet-curable acrylic oligomer and the ultraviolet-curable monomer, photopolymerization initiator, thiol, organic solvent, etc., which are blended as needed, an inorganic pigment, an organic pigment, a surfactant other than a fluorine-containing surfactant, etc.

[0067] The viscosity of the ultraviolet-curable acrylic resin composition solution used in the present invention is not particularly limited, but is preferably 1 mPa·s or more, more preferably 3 mPa·s or more, and particularly preferably 5 mPa·s or more at 25° C. The upper limit of the viscosity is not particularly limited, but is preferably 100 mPa·s or less, more preferably 30 mPa·s or less, and particularly preferably 10 mPa·s or less.

[0068] (2) Silane-Modified Inorganic Particles The ultraviolet-curable acrylic resin composition contains silane-modified inorganic particles. <Inorganic Particles> Specific examples of silane-modified inorganic particles include silica, alumina, zeolite, and titanium oxide. Of these, silica is preferred. The particle size of the inorganic particles is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more. The upper limit of the particle size is not particularly limited, but is preferably 200 nm or less, more preferably 150 nm or less. Note that even when these inorganic particles are silane-modified, the particle size hardly changes.

[0069] <Silane Modification> Silane-modified inorganic particles can be obtained by modifying (coating or surface treating) a part or all of the surface of the inorganic particles with silane. For example, when silica is used as the inorganic particles, silane-modified inorganic particles can be obtained by treating and coating a part or all of the silanol groups on the surface of the silica particles with silane. The same applies to other inorganic particles such as alumina and zeolite.

[0070] <Silane> Examples of silanes used for modification include alkylsilanes, arylsilanes, arylalkylsilanes, and olefinylsilanes. Of these, alkylsilanes are preferred. Preferred examples of alkylsilanes include tetramethylsilane, octadecyltrimethoxysilane, methyltrimethoxysilane, and hexyltrimethoxysilane. These may be used alone or in combination of two or more.

[0071] <Preparation Method> The silane-modified inorganic particles used in the present invention can be prepared by blending inorganic particles, silane, and, if necessary, a dispersant, a dispersion medium, etc. to form an inorganic particle mixture, and then stirring the mixture. This results in an inorganic particle dispersion containing silane-modified inorganic particles. For example, when silica is used as the inorganic particles, a silane-modified silica sol is obtained.

[0072] The dispersant is not particularly limited, but examples thereof include a polyfunctional comb-type functional polymer (polyfunctional comb-type surfactant) having an ionic group in the main chain and a polyoxyalkylene chain in the graft chain. By shortening the length of the main chain, excellent dispersibility is exhibited, particularly for fine particles of about 1 μm or less.

[0073] The dispersion medium is not particularly limited, but water or an organic solvent is used, preferably an organic solvent is used. The organic solvent is not particularly limited, but examples thereof include aromatic hydrocarbon solvents such as xylene and toluene; alcohol solvents such as methanol, ethanol, isopropyl alcohol, and 1-hexanol; and ketone solvents such as methyl ethyl ketone, and these can be used in combination as appropriate.

[0074] The amount of inorganic particles in the inorganic particle mixture is not particularly limited, but is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 100 parts by weight of the inorganic particle mixture. The upper limit of the amount of inorganic particles is not particularly limited, but is preferably 50 parts by mass or less, more preferably 30 parts by mass or less.

[0075] The amount of silane to be added per 100 parts by weight of the inorganic particle mixture is not particularly limited, but is preferably 1 part by mass or more, more preferably 3 parts by mass or more. The upper limit of the amount of silane to be added is not particularly limited, but is preferably 20 parts by mass or less, more preferably 8 parts by mass or less.

[0076] The amount of dispersant to be added per 100 parts by weight of the inorganic particle mixture is not particularly limited, but is preferably 1 part by mass or more, more preferably 2 parts by mass or more. The upper limit of the amount of dispersant to be added is not particularly limited, but is preferably 20 parts by mass or less, more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0077] The amount of the dispersion medium to be added per 100 parts by weight of the inorganic particle mixture is not particularly limited, but is preferably 10 parts by mass or more, more preferably 35 parts by mass or more, and particularly preferably 54 parts by mass or more. The upper limit of the amount of the dispersion medium to be added is not particularly limited, but is preferably 90 parts by mass or less, and more preferably 84 parts by mass or less.

[0078] The method of stirring the inorganic particles, silane, and optionally a dispersant, dispersion medium, and the like after blending is not particularly limited, but any commercially available device such as a disperser that can perform homogeneous mixing and dispersion in a short period of time can be used, for example, a product called "Paint Conditioner 1400-0H" (manufactured by Red Devil Co., Ltd.).

[0079] The stirring conditions are not particularly limited, but examples include a stirring temperature of 23 to 28°C (room temperature), a vibration speed of 600 rpm or more, and a stirring time of about 1 to 5 hours. Furthermore, mixing and dispersion can also be carried out by blending beads such as zirconia beads used in bead mills for pulverization and dispersion. Beads with a diameter of about 0.3 to 2.0 mm can be preferably used.

[0080] <Primary Particle Diameter> The silane-modified inorganic particles obtained by the above method have a primary particle diameter of 10 to 200 nm. Specifically, the lower limit of the primary particle diameter is 10 nm, preferably 20 nm, and the upper limit is 200 nm, preferably 150 nm. The primary particle diameter here refers to the size of a unit particle (particle diameter) that is recognized as the smallest particle unit judging from the apparent geometric shape, and can be measured using a laser diffraction scattering method. Note that, since the particle diameter hardly changes even when inorganic particles are modified with silane, in the present invention, the average particle diameter of the inorganic particles before silane modification is defined as the particle diameter of the silane-modified inorganic particles.

[0081] <Content of inorganic particle dispersion> The content of the inorganic particle dispersion containing silane-modified inorganic particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin composition solution containing the solvent. The upper limit of the content is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less.

[0082] (3) Preparation of UV-Curable Acrylic Resin Composition Solution The UV-curable acrylic resin composition solution of the present invention can be obtained by charging predetermined amounts of the inorganic particle dispersion containing the UV-curable acrylic oligomer and silane-modified inorganic particles described above, as well as materials such as a UV-curable monomer, a photopolymerization initiator, a thiol compound, and a solvent, which are blended as needed, into a container and stirring them. The UV-curable acrylic resin composition solution thus obtained can be used in inkjet printing, preferably as an inkjet ink described below, to form a resin film.

[0083] (4) Resin film The resin film of the present invention is composed of an ultraviolet-curable acrylic resin cured product obtained by curing the ultraviolet-curable acrylic resin composition by irradiating it with ultraviolet light. The resin film of the present invention is a porous film having minute pores, and although it does not contain fluorine, it has water repellency and oil repellency equivalent to those of fluorine-based porous films.

[0084] The ultraviolet-curable acrylic resin cured product contains silane-modified inorganic particles. The content of the silane-modified inorganic particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more, based on the total amount of the ultraviolet-curable acrylic resin cured product. The upper limit of the content is not particularly limited, but is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[0085] If the content of the silane-modified inorganic particles is too low, the water repellency and oil repellency of the resin film may decrease, whereas if the content is too high, the resin film may turn white.

[0086] <Surface Unevenness> The resin film of the present invention has unevenness on its surface within ±2,500 nm of a reference value. The surface of the resin film is photographed with a laser microscope to obtain a surface image containing height information, and the average height of the unevenness (reference value) is calculated based on the cross-sectional shape obtained from the surface image. The plane containing this value is used as the reference plane.

[0087] A laser microscope capable of acquiring surface images containing height information, such as the "VK-X3000" (manufactured by Keyence Corporation), can be used. As a method for determining the cross-sectional shape from a surface image and setting a reference value for the height of the irregularities, for example, the analysis app included with the "VK-X3000" (manufactured by Keyence Corporation) can be used to confirm the cross-sectional shape and create a cross-sectional curve based on it. In this case, the analysis app automatically sets the average height (the reference value obtained by averaging the high and low points of the cross-sectional shape) to 0, and areas higher than the reference plane including this can be expressed as a + value, and areas lower than this reference plane can be expressed as a - value. The numerical values ​​of the surface irregularities in the resin film of the present invention are determined as described above.

[0088] The resin film of the present invention has a surface unevenness within ±2,500 nm (= 2.5 μm) of the reference value. Preferably, the surface unevenness is within ±2,000 nm, more preferably within ±1,500 nm, of the reference value. When the surface unevenness is within this range, the specific surface area is increased, and a large number of silane-modified inorganic particles can be scattered on the surface, thereby improving water and oil repellency. There is no particular lower limit for the surface unevenness, but it is preferably at least ±100 nm, more preferably at least ±500 nm, from the reference plane.

[0089] <Through holes> The resin film of the present invention is a porous film having fine pores present therein. Such pores include through holes that communicate from the front surface to the back surface, non-penetrating pores, etc. Examples of through holes that communicate from the front surface to the back surface include a case where a single pore penetrates from the front surface to the back surface of the film, and a case where multiple fine pores are present in a connected state and penetrate from the front surface to the back surface of the film.

[0090] However, in the present invention, it is desirable that there are substantially no through holes of a certain size or larger, which makes it possible to effectively prevent penetration of water, solvents, etc. while maintaining good breathability.

[0091] Here, through-holes of a certain size or larger refer to those that can be observed in a cross-sectional photograph taken at 30,000 magnification using a field emission scanning electron microscope (FE-SEM). In the present invention, it is desirable that through-holes that communicate from the front surface to the back surface are not substantially observed in a cross-sectional photograph taken at 30,000 magnification using an FE-SEM. Alternatively, the resin film of the present invention may have through-holes that communicate from the front surface to the back surface, as long as they are of a size that cannot be confirmed in a cross-sectional photograph taken at 30,000 magnification using an FE-SEM. This makes it possible to achieve a high level of both good breathability and waterproofness (or the effect of suppressing the penetration of liquids such as water and solvents).

[0092] <Breathability> The resin film of the present invention has a breathability of 10 to 300 seconds / 100 mL, preferably 10 to 200 seconds / 100 mL, and particularly preferably 10 to 60 seconds / 100 mL, according to JIS L1096 B method (Gurley method). If the breathability is within the above range, good sound permeability can be maintained.

[0093] Furthermore, the resin film of the present invention preferably has a water pressure resistance of 10 to 400 kPa, more preferably 30 to 400 kPa, according to JIS L 1092 Method B (high water pressure method). When the water pressure resistance is in the range of 10 to 400 kPa, high sound permeability and waterproofness can be obtained.

[0094] The resin film of the present invention preferably has a breaking elongation of 100 to 500%, more preferably 150 to 400%, and particularly preferably 80 to 260%, as measured in accordance with JIS L 1096. If the breaking elongation is 100 to 500%, good sound permeability and sufficient waterproofing can be maintained.

[0095] The resin film of the present invention also has sound permeability such that the acoustic loss at a frequency of 1 kHz is less than 10 dB, the acoustic loss at a frequency of 2 kHz is less than 5 dB, and the acoustic loss at a frequency of 5 kHz is less than 5 dB.

[0096] <Thickness of Resin Film> The thickness of the resin film is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. The upper limit of the film thickness is not particularly limited, but is preferably 100 μm or less, more preferably 70 μm or less, even more preferably 50 μm or less, and particularly preferably 35 μm or less.

[0097] 2. Method for Producing Resin Film The method for producing the resin film of the present invention is not particularly limited, but as an example, it can be produced by a method including the following steps A to D.

[0098] Step A: A step of forming a film made of an ultraviolet-curable acrylic resin composition solution containing at least an ultraviolet-curable acrylic oligomer, an ultraviolet-curable monomer, silane-modified inorganic particles having a primary particle size of 10 to 200 nm, a photopolymerization initiator, and a solvent on a release material. Step B: A step of irradiating the film obtained in Step A with ultraviolet light to temporarily cure it, thereby forming a temporarily cured film having a phase separation structure. Step C: A step of heat-treating the temporarily cured film obtained in Step B. Step D: A step of irradiating the temporarily cured film with ultraviolet light after Step C to permanently cure it.

[0099] (1) Step A In step A of the production method of the present invention, a film (coating film) made of an ultraviolet-curable acrylic resin composition solution containing at least an ultraviolet-curable acrylic oligomer, an ultraviolet-curable monomer, silane-modified inorganic particles having a primary particle size of 10 to 200 nm, and a solvent is formed on a release material.

[0100] Any of the conventionally known release agents can be used, and preferred examples include a substrate such as paper or film on which a polyolefin film such as a polyethylene film, a polypropylene film, or a polymethylpentene film is laminated as a release layer, and a substrate such as paper or film coated with a silicone-based or fluorine-based release agent.

[0101] The method for forming a film made of the ultraviolet-curable acrylic resin composition solution on the release material is not particularly limited, but a printing method using an ink made of the ultraviolet-curable acrylic resin composition solution is preferably used. As the printing method, known methods such as gravure printing, screen printing, photolithography, gravure offset printing, xerography, stamping, flexographic printing, painting, air brushing, and inkjet printing can be applied.

[0102] Among these, screen printing and inkjet printing are more preferred, and inkjet printing is particularly preferred. It is preferable to prepare an ink consisting of a solution of an ultraviolet-curable acrylic resin composition in advance, and then use the ink to apply a coating film onto a release material by inkjet printing. The thickness of the coating film thus formed is not particularly limited, but is preferably 10 to 150 μm, more preferably 20 to 100 μm, and particularly preferably 30 to 80 μm.

[0103] An ink made of an ultraviolet-curable acrylic resin composition solution (hereinafter simply referred to as "ink") can be prepared by pre-mixing an ultraviolet-curable acrylic oligomer, an ultraviolet-curable monomer, a dispersion of silane-modified inorganic particles having a primary particle size of 10 to 200 nm, a solvent, and, as necessary, a photopolymerization initiator, a thiol compound, and the like.

[0104] The amount of the solvent used is preferably 30% by mass or more, more preferably 40% by mass or more, and particularly preferably 50% by mass or more, based on the total amount of the ink. There is no particular upper limit to the amount used, but it is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less. When the amount of the solvent used is within the above range, coating unevenness, thickness unevenness, and the like can be prevented.

[0105] The viscosity of the ink is not particularly limited, but in the case of an inkjet ink, the viscosity at 25° C. is preferably 1 mPa·s or more, and more preferably 5 mPa·s or more. The upper limit of the viscosity of the ink at 25° C. is not particularly limited, but is preferably 30 mPa·s or less, and more preferably 25 mPa·s or less.

[0106] Details of the ultraviolet-curable acrylic oligomer, ultraviolet-curable monomer, silane-modified inorganic particles having a primary particle size of 10 to 200 nm, solvent, and other additives such as a photopolymerization initiator and a thiol compound that are blended as needed, which are contained in the ink, are as described above.

[0107] As the ultraviolet-curable acrylic oligomer contained in the ink, it is preferable to use a bifunctional urethane (meth)acrylate oligomer having a urethane bond and a (meth)acrylic group in the molecule, because this results in excellent flexibility of the coating film after curing.

[0108] The ultraviolet-curable monomer contained in the ink is preferably a cyclopolymerizable monomer and / or a combination of one or more monomers containing t-butyl acrylate, and particularly preferably a combination of one or more monomers containing t-butyl acrylate.

[0109] When t-butyl acrylate is used in combination with other ultraviolet-curable monomers, the content of the t-butyl acrylate is preferably 3% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, based on the total amount of the ultraviolet-curable monomers. There is no particular upper limit to the content, but it is preferably 50% by mass or less, more preferably 30% by mass or less.

[0110] Furthermore, the content of t-butyl acrylate in the ink is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more, relative to the total amount of the ink. There is no upper limit to the content, but it is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 7% by mass or less.

[0111] The content of the ultraviolet-curable monomer in the ink is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more, based on the total amount of the ink. The upper limit of the content is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0112] (2) Step B In step B, the film (coated film) formed in step A is temporarily cured by irradiating it with ultraviolet light to form a temporarily cured film having a phase separation structure.

[0113] The irradiation in step B is provisional irradiation, which does not completely cure the ultraviolet-curable acrylic resin composition but leaves it in a provisionally cured state, and simultaneously induces phase separation.

[0114] When the ultraviolet-curable acrylic resin composition solution is in the stage of a mixed liquid (ink = coating liquid before ultraviolet irradiation) obtained by mixing the respective components, it is a homogeneous solution in which the ultraviolet-curable acrylic oligomer and the ultraviolet-curable monomer are miscible and the inorganic particles are uniformly dispersed, but after preliminary ultraviolet irradiation, a component (polymer) that is insoluble in the solvent is produced by photopolymerization, and the component separates from the solvent to form a phase-separated structure in which the component is dispersed in the solvent, within which inorganic particles are further uniformly dispersed.

[0115] Although the criteria for provisional curing are not particularly limited, it can be determined that phase separation between the solvent and the polymer has been induced in the coating film when, for example, a film that was transparent before UV irradiation becomes opaque (whitens) after irradiation.

[0116] Specifically, in step B, ultraviolet irradiation can be carried out using an ultraviolet light source having a peak at 365 to 410 nm, more preferably a UV lamp having a peak at 365 nm. The cumulative light amount is not particularly limited, but is preferably 800 mJ / cm. ２ or less, more preferably 750 mJ / cm ２ Particularly preferably 500 mJ / cm or less ２ By irradiating with ultraviolet light as follows, a desired temporarily cured film can be obtained.

[0117] The lower limit of the cumulative light amount is not particularly limited, but is preferably 150 mJ / cm ２ More preferably, 200 mJ / cm ２ More preferably, 300 mJ / cm ２ Ultraviolet light can be irradiated so as to achieve the above.

[0118] In addition, in step B, cations can be generated by ultraviolet irradiation, which can induce foaming. Then, foaming can be generated by heat treatment in step C, which will be described later.

[0119] (3) Step C In Step C, the provisionally cured film obtained in Step B is heat-treated. That is, the solvent in the provisionally cured film is removed by heating, and foaming progresses. The heat-treatment method is not particularly limited, and examples thereof include conventionally known methods such as leaving the film in a dryer. The heating temperature is preferably 60 to 150°C, more preferably 80 to 120°C, and the heating time is preferably 10 to 120 minutes, more preferably about 20 to 100 minutes.

[0120] In the present invention, preferably, cations are generated in the above-mentioned step B, and then heat treatment is performed in step C to promote foaming, thereby generating minute pores throughout the film, and breathability can be imparted after removal of the solvent. However, it is desirable that the minute pores formed do not substantially include through-holes that communicate from the front surface to the back surface of the film. Note that if the solvent is removed without heat treatment, breathability may not be confirmed.

[0121] (4) Step D In step D, after step C, the temporarily cured film is irradiated with ultraviolet light to effect full curing. The irradiation conditions for full curing are not particularly limited, but specifically, an integrated light amount of preferably 500 mJ / cm is used, for example, with a UV lamp having a peak at 365 nm. ２ More preferably, 700 mJ / cm ２ By irradiating with ultraviolet light in the above manner, the desired fully cured film can be obtained.

[0122] The upper limit of the cumulative light amount is not particularly limited, but is preferably 2000 mJ / cm ２ or less, more preferably 1500 mJ / cm ２ Particularly preferably 1000 mJ / cm or less ２ The ultraviolet light can be irradiated as follows:

[0123] The resin film of the present invention can be obtained by separating the cured film thus obtained from the release agent. Note that the resin film of the present invention is not limited to these manufacturing methods, and may be manufactured by other methods as long as it has the physical properties specific to the present invention.

[0124] The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is of course possible to carry out the invention by making appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0125] <Preparation of Silane-Modified Inorganic Particle Dispersion> The components shown in Table 1 below were prepared in the blending ratios (parts by mass) shown in Table 1, and dispersed for 3 hours using 0.5 mm zirconia beads in a stirrer (product name "Paint Conditioner 1400-0H"; manufactured by Red Devil Co., Ltd.) (vibration speed: 1725 revolutions per minute at a frequency of 60 Hz, temperature: 25°C), to obtain inorganic particle dispersions A to C.

[0126]

[0127] ・Product name "HSP-6A" (manufactured by Fuso Scientific Industries, Ltd.) ・Product name "QSG-30, QSG-100" (manufactured by Shin-Etsu Chemical Co., Ltd.) ・1-Hexanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ・Product name "Marialim SC-0505K" (manufactured by NOF Corporation) ・Octadecyltrimethoxysilane, tetramethylsilane (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0128] <Preparation of Inks 1 to 5> The components shown in Table 2 were mixed in the blending ratios (parts by mass) shown in Table 2 to prepare inks 1 to 5 made of ultraviolet-curable acrylic resin compositions.

[0129]

[0130] Product name "CN996": urethane acrylate oligomer (manufactured by Sartomer Corporation) Product name "DPHA": dipentaerythritol hexaacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) Product name "AOMA": cyclopolymerizable monomer (manufactured by Nippon Shokubai Co., Ltd.) t-butyl acrylate: manufactured by Tokyo Chemical Industry Co., Ltd.

[0131] Product name "PE-1": pentaerythritol tetrakis(3-mercaptobutyrate) (manufactured by Resonac Co., Ltd.) Product name "BD-1": 1,4-bis(3-mercaptobutyryloxy)butane (manufactured by Resonac Co., Ltd.)

[0132] Product name "Omnirad 184": 1-hydroxycyclohexyl-phenyl ketone; IGM Resins B.V. Product name "Irgacure 290": high molecular weight sulfonium tetrakis[pentafluorophenyl]borate (manufactured by BASF Japan Ltd.)

[0133] <Preparation of Resin Liquid 1 (Polyurethane Resin Liquid)> The following components were mixed to prepare a polyurethane resin liquid. CRISBON MP880PS: 100 parts by mass (DIC Corporation, polycarbonate-based polyurethane resin, solid content 30% by mass); LAZROID LU2850M: 25 parts by mass (Dainichiseika Color & Chemicals Mfg. Co., Ltd., silica fine particle dispersion, solid content 20% by mass); DILAC BLACK L1584: 4 parts by mass (DIC Corporation, black pigment, solid content 25% by mass); N,N-dimethylformamide: 42 parts by mass.

[0134] [Examples 1 to 6, Comparative Example 1] Inks 1 to 5 were applied to a polyolefin release film (trade name "DECOFIT"; Toray Industries, Inc., size = 80 × 300 mm) by an inkjet method so that the wet film thickness was 65 μm, thereby obtaining a coated film. The coated film was then temporarily cured by irradiating it with ultraviolet light using a high-pressure mercury lamp with a peak at 365 nm, thereby obtaining a temporarily cured film.

[0135] Next, the provisionally cured film was subjected to a heat treatment at 100°C for 1 hour using a dryer to remove the solvent. Subsequently, the provisionally cured film after the heat treatment was irradiated with ultraviolet light using a high-pressure mercury lamp having a peak at 365 nm to perform final curing, thereby obtaining a final cured film. The integrated light amount (unit: mJ / cm) of ultraviolet light irradiation during provisional curing and final curing in each example and comparative example was ２ The thickness of the cured film was 20 μm.

[0136] [Comparative Example 2] Resin solution 1 was applied to a polyester silicone release film (manufactured by Fujimori Kogyo Co., Ltd., 75E-0010DG-2AS) using a knife-on-roll coater so that the thickness of the resulting resin film would be 30 μm. It was then immersed in 20°C water for 1.5 minutes to allow complete solidification. It was then washed in 50°C warm water for 5 minutes, and then heat-treated at 130°C for 2 minutes to dry. The release film was then removed from the resulting film to obtain a resin film.

[0137] [Measurement Methods] <Water Repellency> Water contact angle (degrees; °) was measured using the θ / 2 method in accordance with ISO 19403. <Oil Repellency> Measurement was performed using the AATCC 118 method, and the average value of n=3 was used. The results are expressed in terms of reagent grades. Grades range from 1 to 8, with grade 8 being the highest grade (highest oil repellency). <Breathability> Air permeability was measured using JIS L1096 8.26.2 B method (Gurley type method).

[0138] <Surface Unevenness> The surface of the obtained resin film was photographed using a laser microscope (product name "VK-X3000"; manufactured by Keyence Corporation) to obtain a surface image including height information. Figure 1 shows a micrograph (measurement results) of the resin film obtained in Example 1.

[0139] Next, a cross-sectional curve was created from the obtained surface image using the analysis application attached to the product name "VK-X3000" (manufactured by Keyence Corporation). Figure 2 shows a graph of the cross-sectional curve created based on the micrograph of the resin film obtained in Example 1. The surface unevenness value (nm) was determined by setting the average height (the value obtained by averaging the high and low points of the cross-sectional shape = reference value) automatically set by the analysis application to 0. Measurements were taken at 50 randomly selected different points on the surface of the resin film, and the ranges within which the measured values ​​fell are shown in Table 3.

[0140] <Presence or Absence of Through Holes> Cross-sectional photographs of the obtained resin films were taken at 30,000 magnifications using a field emission scanning electron microscope (FE-SEM), and the presence or absence of through holes that communicated from the front surface to the back surface was observed and evaluated. Cross-sectional photographs of the resin films of Example 1, Example 6, and Comparative Example 2 are shown in Figure 3, Figure 4, and Figure 5, respectively.

[0141] The size of the through holes in Comparative Example 2 was measured by taking a vertical cross-sectional photograph at 300 to 5000 magnifications using a scanning electron microscope (product name "S-3000N", manufactured by Hitachi High-Technologies Corporation), measuring the diameters of 100 holes in any range of the obtained image, and calculating the average value, which was used as the average pore diameter.

[0142]

[0143] The resin film of the present invention does not contain fluorine and has not only acoustic performance (sound permeability) and breathability but also high water and oil repellency, so it can be used as a suitable sound-permeable waterproof film.

Claims

1. A resin film composed of a cured ultraviolet-curable acrylic resin containing silane-modified inorganic particles with a primary particle diameter of 10 to 200 nm, wherein the surface of the resin film has irregularities within ±2,500 nm of a reference value, where the reference value is the average height of irregularities determined based on a cross-sectional shape obtained from an image of the surface taken with a laser microscope, which includes height information, and the resin film has an air permeability of 10 to 300 seconds / 100 mL according to JIS L1096 Method B (Gurley method).

2. The resin film according to claim 1, having a film thickness of 1 to 100 μm.

3. The resin film according to claim 1, wherein the content of the silane-modified inorganic particles is 1 to 50 mass % based on the total amount of the ultraviolet-curable acrylic resin cured product.

4. A method for producing the resin film according to claim 1, comprising the following steps A to D: Step A: A step of forming a film made of an ultraviolet-curable acrylic resin composition solution containing at least an ultraviolet-curable acrylic oligomer, an ultraviolet-curable monomer, silane-modified inorganic particles having a primary particle size of 10 to 200 nm, a photopolymerization initiator, and a solvent on a release material. Step B: A step of irradiating the film obtained in Step A with ultraviolet light to temporarily cure it, thereby forming a temporarily cured film having a phase separation structure. Step C: A step of heat-treating the temporarily cured film obtained in Step B. Step D: A step of irradiating the temporarily cured film with ultraviolet light after Step C to permanently cure it.

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