Release film and adhesive tape with release film

Abstract

Provided is a non-fluorine-based release film having satisfactory releasability from an adhesive tape. A release film having a release layer on a substrate, wherein the release layer comprises a cured layer of an active energy ray-curable composition that contains a compound having an alkyl group having 8 or more carbon atoms (hereinafter referred to as a "long-chain alkyl compound"), and the average length (RSm) of roughness curve elements of the surface of the release layer, which are measured by an atomic force microscope (AFM), is 300 nm or longer.

Description

Release Film and Adhesive Tape with Release Film

[0001] The present invention relates to a release film and an adhesive tape with a release film.

[0002] The release film is used, for example, for the purpose of protecting the surface of the adhesive tape. The adhesive tape is generally supplied with the release film attached, and the release film is peeled off from the adhesive tape when the adhesive tape is used.

[0003] As the adhesive of the adhesive tape, a silicone adhesive is generally used. As the release film used for the silicone adhesive tape, a release film made of a fluorine-based release agent has been well known (see, for example, Patent Documents 1 to 3).

[0004] Japanese Patent No. 3025262 International Publication No. 2019 / 208141 Japanese Unexamined Patent Application Publication No. 2024-6000

[0005] However, fluorine-based release agents have a high material cost and environmental problems have also been pointed out. Therefore, an object of the present invention is to provide a non-fluorine-based release film having good peelability from an adhesive tape.

[0006] The above object of the present invention has been achieved by the following invention.

[0007] [1] A release film having a release layer on a substrate, wherein the release layer is composed of a cured layer of an active energy ray-curable composition containing a compound having an alkyl group with 8 or more carbon atoms (hereinafter referred to as "long-chain alkyl compound"), and the average length (RSm) of the roughness curve elements measured by an atomic force microscope (AFM) on the surface of the release layer is 300 nm or more.

[0008] [2] The release film according to [1], wherein the active energy ray-curable composition further contains a compound having no alkyl group with 8 or more carbon atoms in the molecule and having an ethylenically unsaturated group (hereinafter referred to as "polymerizable compound (c)").

[0009] [3] The release film according to [1] or [2], wherein the long-chain alkyl compound comprises a compound having an alkyl group having 8 or more carbon atoms and an ethylenically unsaturated group (hereinafter referred to as "polymerizable long-chain alkyl compound (a)").

[0010] [4] The release film according to [2] or [3], wherein the polymerizable compound (c) is a compound that does not have an alkyl group having 8 or more carbon atoms in its molecule and has 2 to 10 ethylenically unsaturated groups.

[0011] [5] The release film according to any one of [2] to [4], wherein the mass ratio of the long-chain alkyl compound to the polymerizable compound (c) (mass of polymerizable compound (c) / mass of the long-chain alkyl compound) is 1.7 or more and 15.0 or less.

[0012] [6] The release film according to any one of [2] to [5], wherein the total mass of the long-chain alkyl compound and the polymerizable compound (c) is 70% by mass or more with respect to 100% by mass of the total solid content of the active energy ray curable composition.

[0013] [7] The release film according to any one of [1] to [6], wherein the thickness of the release layer is 50 nm or more and less than 600 nm.

[0014] [8] The release film according to any one of [1] to [7], wherein the base material is a polyester film.

[0015] [9] The release film according to any one of [1] to [8], wherein the surface free energy of the surface of the substrate on the release layer side is 40 mN / m or more and 60 mN / m or less.

[0016]

[10] The release film according to any one of [1] to [9], wherein the arithmetic mean height Ra of the roughness curve of the surface of the substrate on the release layer side is 0.03 μm or more and 0.70 μm or less.

[0017]

[11] A release film adhesive tape comprising a silicone adhesive layer of a silicone adhesive tape to which a release film described in any of [1] to

[10] is bonded.

[0018] According to the present invention, a non-fluorine-based release film with good peelability from adhesive tape can be provided.

[0019] This is a schematic side view showing an example of a manufacturing apparatus for the release film of the present invention.

[0020] The release film of the present invention has a release layer on a substrate. The release layer consists of a cured layer of an active energy ray curable composition containing a long-chain alkyl group compound, and is characterized in that the average length (RSm) of the roughness curve elements measured by an atomic force microscope (AFM) on the surface of the release layer is 300 nm or more. Hereinafter, the average length (RSm) of the roughness curve elements measured by an atomic force microscope (AFM) may be abbreviated as "RSm".

[0021] We found that the release layer being a cured layer of an active energy ray curable composition containing a long-chain alkyl compound, and having an RSm of 300 nm or more on the surface of the release layer, improves the peelability from adhesive tapes. In particular, the peelability from silicone-based adhesive tapes is improved. Hereinafter, the peelability between adhesive tape and release film will simply be referred to as "peelability".

[0022] Hereinafter, alkyl groups containing eight or more carbon atoms in long-chain alkyl compounds are sometimes referred to as "long-chain alkyl groups."

[0023] The mechanism by which the release properties of the release film of the present invention are improved is not clear, but it is presumed to be as follows. In a release layer consisting of a cured layer of an active energy ray curable composition containing a long-chain alkyl compound, an RSm of 300 nm or more on the surface of the release layer is presumed to indicate that the orientation of the long-chain alkyl group to the surface of the release layer is progressing. That is, it is presumed that the more the orientation of the long-chain alkyl group progresses, the larger the RSm on the surface of the release layer becomes, and the better the release properties. This effect is particularly effective in improving the release properties with silicone adhesive tapes. Hereinafter, the orientation of the long-chain alkyl group to the surface of the release layer may be abbreviated as "orientation".

[0024] From the above viewpoint, the RSm of the release layer surface is preferably 400 nm or more, more preferably 500 nm or more, even more preferably 700 nm or more, and particularly preferably 800 nm or more. The upper limit is preferably 4,000 nm or less, preferably 3,000 nm or less, even more preferably 2,500 nm, and particularly preferably 2,000 nm or less.

[0025] [Release Layer] The release layer is a cured layer of an active energy ray-curable composition containing a long-chain alkyl compound. Here, the cured layer of an active energy ray-curable composition refers to a layer that has been cured by irradiation with active energy rays.

[0026] Specifically, it is a layer obtained by curing an active energy ray-curable composition coated on a substrate by irradiating it with active energy rays. Examples of active energy rays include ultraviolet light, visible light, infrared light, electron beams, alpha rays, beta rays, and gamma rays. Among these, ultraviolet light and electron beams are preferred, and ultraviolet light is particularly preferred.

[0027] From the viewpoint of enhancing orientation, the number of carbon atoms in the long-chain alkyl group in the long-chain alkyl compound is 8 or more, preferably 10 or more, more preferably 12 or more, and particularly preferably 14 or more. The number of carbon atoms in the long-chain alkyl group is preferably 30 or less, more preferably 28 or less, even more preferably 25 or less, and particularly preferably 23 or less. The long-chain alkyl group may be linear or branched, but a linear chain is preferred from the viewpoint of orientation.

[0028] Long-chain alkyl compounds may or may not be polymerizable. Hereinafter, compounds having an alkyl group with 8 or more carbon atoms and an ethylenically unsaturated group may be referred to as "polymerizable long-chain alkyl compounds (a)," and long-chain alkyl compounds that are not polymerizable may be referred to as "non-polymerizable long-chain alkyl compounds (b)." It is preferable that the long-chain alkyl compound includes at least polymerizable long-chain alkyl compounds (a).

[0029] Here, preferred ethylenically unsaturated groups include acryloyl groups, methacryloyl groups, acryloyloxy groups, methacryloyloxy groups, allyl groups, vinyl groups, and the like.

[0030] As the non-polymerizable long-chain alkyl compound (b), for example, long-chain alkyl group-containing polyvinyl resin, long-chain alkyl group-containing acrylic resin, long-chain alkyl group-containing polyester resin, long-chain alkyl group-containing alkyd resin, long-chain alkyl group-containing ether compound, long-chain alkyl group-containing amine compound, and the like can be preferably used.

[0031] Examples of the polymerizable long-chain alkyl compounds (a) described above are given below, but the present invention is not limited to these. In the following description, "...(meth)acrylate" is a general term for "...acrylate" and "...methacrylate".

[0032] Examples of polymerizable long-chain alkyl compounds (a) include octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0033] From the viewpoint of enhancing orientation, it is preferable that the polymerizable long-chain alkyl compound (a) has a urethane bond in its molecule. Examples of such compounds include compounds obtained by reacting a (meth)acrylate compound (d) having one or more (meth)acryloyl groups and one or more hydroxyl groups in its molecule, a polyisocyanate compound (e) having two or more isocyanate groups in its molecule, and a higher alcohol (f) having 8 to 30 carbon atoms.

[0034] Examples of the above (meth)acrylate compound (d) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, glycerin di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl-acid phosphate, and epoxy Examples include di(meth)acrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol mono(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and (meth)acrylates having 2 to 30 alkylene oxy groups (e.g., ethylene oxy group, propylene oxy group, butylene oxy group, etc.) in the molecule.

[0035] Among the above (meth)acrylate compounds (d), 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and (meth)acrylates having 2 to 30 alkylene oxy groups in the molecule are preferably used.

[0036] Examples of the polyisocyanate compound (e) mentioned above include diisocyanate compounds such as hexamethylene diisocyanate, lysine diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, tollidine diisocyanate, tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate; biuret-type polyisocyanate compounds obtained by reacting these various diisocyanate compounds with water; adduct-type polyisocyanate compounds obtained by reacting various diisocyanate compounds with polyhydric alcohols such as trimethylolpropane; and known polymers obtained by isocyanurating various compounds.

[0037] Among the polyisocyanate compounds (e) listed above, diisocyanate compounds are preferred. Furthermore, from the viewpoint of orientation, diisocyanate compounds having an arylene group, such as naphthalene diisocyanate and diphenylmethane diisocyanate, are preferred.

[0038] Examples of the above-mentioned higher alcohol (f) include linear higher alcohols such as octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetanol, cetostearyl alcohol, stearyl alcohol, and behenyl alcohol; linear unsaturated higher alcohols such as oleyl alcohol; and branched higher alcohols such as 2-hexyldecanol, 2-octyldodecanol, and 2-decyltetradodecanol. Linear higher alcohols are preferred from the viewpoint of orientation.

[0039] Commercially available products can be used as the above-mentioned higher alcohol (f). For example, as linear saturated higher alcohols, "Conol (registered trademark)" 10WS, Conol 1098, Conol 1275, Conol 20F, Conol 20P, Conol 1495, Conol 1670, Conol 1695, Conol 30CK, Conol 30OC, Conol 30RC, Conol 30F, Conol 30S, Conol 30SS, Conol 30T, Conol 2265, Conol 2280 (New Japan (Product name of Honri-ka Co., Ltd.) "Calcol (registered trademark)" 0898, Calcol 0880, Calcol 1098, Calcol 2098, Calcol 4098, Calcol 6098, Calcol 8098, Calcol 200GD, Calcol 2475, Calcol 2474, Calcol 2473, Calcol 2463, Calcol 2455, Calcol 2450, Calcol 4250, Calcol 6870 , Calcol 6850, Calcol 8688, Calcol 8665, Calcol 220-80 (product name of Kao Corporation), as linear unsaturated higher alcohols, "Licacol (registered trademark)" 60B, Licacol 70B, Licacol 75BJ, Licacol 85BJ, Licacol 90B, Licacol 90BR, Licacol 90BHR, Licacol 110BJ, "Angecol (registered trademark)" 50A, A Examples of such alcohols include Njecol 60AN, Njecol 70AN, Njecol 80AN, Njecol 85AN, Njecol 90AN, Njecol 90NR, Njecol 90NHR (product names of Shin-Nippon Rika Co., Ltd.), and branched higher alcohols such as "Njecol (registered trademark)" 160BR, Njecol 200A, and Njecol 240A (product names of Shin-Nippon Rika Co., Ltd.).

[0040] The long-chain alkyl group contained in the above higher alcohol (f) preferably has 10 or more carbon atoms, more preferably 12 or more, and particularly preferably 14 or more. The above number of carbon atoms is preferably 30 or less, more preferably 28 or less, even more preferably 25 or less, and particularly preferably 23 or less. The above long-chain alkyl group may be a linear alkyl group or a branched alkyl group, but a linear alkyl group is preferred from the viewpoint of orientation.

[0041] The active energy ray-curable composition preferably further contains a compound having no long-chain alkyl group in the molecule and having an ethylenically unsaturated group (hereinafter sometimes referred to as "polymerizable compound (c)"). Here, examples of the ethylenically unsaturated group preferably include an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, an allyl group, a vinyl group, and the like.

[0042] Examples of the polymerizable compound (c) above include methyl (meth)acrylate, ethyl diethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxytri (meth)acrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol mono(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, Examples include dipentaerythritol hexa(meth)acrylate, tripentaerythritol tri(meth)acrylate, tripentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate hexamethylene diisocyanate urethane pre-oligomer, pentaerythritol tri(meth)acrylate-toluene diisocyanate urethane oligomer, and pentaerythritol tri(meth)acrylate-isophorone diisocyanate urethane oligomer.

[0043] Among the above-mentioned polymerization compounds (c), from the viewpoint of orientation, compounds having 2 to 10 ethylenically unsaturated groups in the molecule are preferred, compounds having 3 to 9 ethylenically unsaturated groups in the molecule are more preferred, and compounds having 4 to 8 ethylenically unsaturated groups in the molecule are even more preferred. Among these, compounds having a theoretical number average molecular weight of 400 or more and less than 1,000 and having 5 to 7 ethylenically unsaturated groups are particularly preferred. Representative examples of the above compounds include, but are not limited to, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. Here, the theoretical number average molecular weight is calculated from its molecular formula structure. In the case of commercially available products, etc., the theoretical number average molecular weight is the number average molecular weight described in the catalog, etc., or is calculated from the described molecular formula structure.

[0044] The content of the long-chain alkyl compound (the total amount of the polymerizable long-chain alkyl compound (a) and the non-polymerizable long-chain alkyl compound (b)) in the active energy ray curable composition is preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 7% by mass or more, and particularly preferably 10% by mass or more, based on 100% by mass of the total solid content of the active energy ray curable composition, from the viewpoint of enhancing the orientation. On the other hand, if the content of the long-chain alkyl compound becomes too large, the strength (hardness) of the release layer may decrease and the solvent resistance and heat resistance may decrease. Therefore, the content of the long-chain alkyl compound is preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0045] The content of the polymerizable compound (c) in the active energy ray curable composition is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 65% by mass or more, and particularly preferably 70% by mass or more, based on 100% by mass of the total solid content of the active energy ray curable composition, from the viewpoint of enhancing the strength (hardness) of the release layer. On the other hand, from the viewpoint of enhancing the orientation, the content of the polymerizable compound (c) is preferably 95% by mass or less, more preferably 90% by mass or less, more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0046] The mass ratio of polymerizable compound (c) to the mass of long-chain alkyl compound contained in the active energy ray curable composition (mass of polymerizable compound (c) / mass of long-chain alkyl compound) is preferably 1.7 or higher, more preferably 2.0 or higher, even more preferably 2.5 or higher, and particularly preferably 3.5 or higher. The above mass ratio is preferably 15.0 or lower, more preferably 12.0 or lower, even more preferably 10.0 or lower, and particularly preferably 9.0 or lower.

[0047] The total content of the long-chain alkyl compound and polymerizable compound (c) in the active energy ray curable composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the total solid content of the composition. The above total content is preferably 100% by mass or less, more preferably 98% by mass or less, and particularly preferably 95% by mass or less.

[0048] The active energy ray curable composition preferably further contains a photopolymerization initiator. Specific examples of such photopolymerization initiators include carbonyl compounds such as acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, methylbenzoyl formate, p-isopropyl-α-hydroxyisobutylphenone, α-hydroxyisobutylphenone, 2,2-dimethoxy-2-phenylacetophenone, and 1-hydroxycyclohexylphenyl ketone, as well as sulfur compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone. These photopolymerization initiators may be used individually or in combination of two or more.

[0049] The above-mentioned photopolymerization initiators are generally commercially available and can be used. For example, Ciba Specialty Chemicals Co., Ltd.'s "Irgacure (registered trademark)" 184, Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, Irgacure 1870, Irgacure OXE01, "DAROCUR (registered trademark)" TPO, DAROCUR 1173, etc., and Nippon Siber Hegner Co., Ltd.'s "Speedcure (registered trademark)" MBB, Speedcure PBZ, Speedcure ITX, Speedcure CTX, Speedcure EDB, "Esacure (registered trademark)" ONE, Esacure Examples include KIP150, Esacure KTO46, and Nippon Kayaku Co., Ltd.'s "KAYACURE®" DETX-S, KAYACURE CTX, KAYACURE BMS, KAYACURE DMBI, etc.

[0050] The content of the above-mentioned photopolymerization initiator is preferably in the range of 0.1 to 15% by mass, and more preferably in the range of 0.5 to 10% by mass, based on 100% by mass of the total solid content of the active energy ray curable composition.

[0051] The release layer preferably does not contain fluorine-based compounds. In other words, the active energy ray curable composition preferably does not contain fluorine-based compounds. Even if a fluorine-based compound is included, its content is preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, and most preferably 0% by mass, based on 100% by mass of the total solid content of the active energy ray curable composition.

[0052] From the viewpoint of release properties with silicone adhesive tapes, it is preferable that the release layer substantially does not contain conventionally known silicone-based release agents. Here, substantially free means that the amount is 3% by mass or less based on 100% by mass of the total solid content of the active energy ray curable composition. The above content is preferably 2% by mass or less, more preferably 1% by mass or less, and most preferably 0% by mass.

[0053] The release layer is preferably free of particles. If the release layer contains particles, the orientation may decrease. It is most preferable that the release layer contains no particles at all, but even if particles are included, the amount is preferably less than 1.0% by mass, more preferably less than 0.5% by mass, and even more preferably less than 0.1% by mass, based on 100% by mass of the total solid content of the active energy ray curable composition.

[0054] From the viewpoint of release properties, the thickness of the release layer is preferably 50 nm or more, more preferably 80 nm or more, even more preferably 120 nm or more, and particularly preferably 150 nm or more. On the other hand, from the viewpoint of orientation, it is preferably less than 600 nm, more preferably less than 500 nm, even more preferably less than 400 nm, and particularly preferably less than 350 nm.

[0055] [Substrate] The substrate is not particularly limited, and known substrates can be used. Examples include plastic film, paper, resin-laminated paper, and resin-impregnated paper. Among these, plastic film and resin-laminated paper are preferred, and plastic film is particularly preferred, from the viewpoint of preventing the penetration of the active energy ray-curable composition into the substrate during the manufacturing process of the release film.

[0056] Examples of the resin-laminated paper mentioned above include paper such as kraft paper laminated with polyethylene resin.

[0057] Examples of the above-mentioned plastic films include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film; polyolefin films such as polypropylene film and polyethylene film; cellulose films such as diacetylcellulose film and triacetylcellulose film; polysulfone film, polyetheretherketone film, polyethersulfone film, polyphenylene sulfide film, polyetherimide film, polyimide film, polyamide film, acrylic film, cyclic olefin film, and polycarbonate film. Among these, polyester film is preferred, and polyethylene terephthalate film is even more preferred.

[0058] From the viewpoint of processability and handling of the release film and the adhesive tape with release film described later, the thickness of the base material is preferably 20 μm or more, more preferably 25 μm or more, and particularly preferably 35 μm or more. On the other hand, if the thickness of the base material increases, the rigidity increases and the release feel may deteriorate, so the thickness of the base material is preferably less than 100 μm, more preferably less than 80 μm, and particularly preferably less than 60 μm.

[0059] The surface free energy of the substrate on the side facing the release layer is preferably 40 mN / m or more, more preferably 43 mN / m or more, and particularly preferably 45 mN / m or more, from the viewpoint of adhesion to the release layer and the applicability of the release layer. The upper limit is preferably 60 mN / m or less. Here, the surface free energy can be measured using a contact angle meter, for example, Kyowa Interface Science Co., Ltd.'s "Drop Master DM501". Details will be described later.

[0060] From the viewpoint of adhesion between the substrate and the release layer, and the applicability of the release layer, the arithmetic mean height Ra of the roughness curve of the surface of the substrate on the release layer side is preferably 0.03 μm or more, more preferably 0.05 μm or more, and particularly preferably 0.10 μm or more. The above Ra is preferably 0.70 μm or less, more preferably 0.50 μm or less, and particularly preferably 0.40 μm or less. The method for measuring the above Ra will be described later.

[0061] [Method for manufacturing release film] The release film of the present invention is preferably obtained, for example, by applying an active energy ray-curable composition onto a substrate, drying it, irradiating it with active energy rays, curing it, and forming a release layer.

[0062] When applying an active energy ray-curable composition onto a substrate, it is preferable that the active energy ray-curable composition is adjusted with an organic solvent so that the solid content concentration is 1 to 10% by mass. The above solid content concentration is more preferably 2 to 8% by mass, and particularly preferably 3 to 6% by mass.

[0063] Examples of the above-mentioned organic solvents include toluene, xylene, methanol, ethanol, isopropyl alcohol, isobutanol, n-butanol, methyl ethyl ketone, hexane, heptane, and cyclohexanone, which can be used individually or in combination of two or more.

[0064] In the above manufacturing process, controlling the drying rate is effective in improving orientation. For example, orientation is preferably promoted by drying at a relatively low temperature in the initial drying stage and at a relatively high temperature in the later drying stage. For example, the drying temperature in the initial drying stage is preferably 30°C to 50°C, and the drying temperature in the later drying stage is preferably 70°C to 95°C. An intermediate drying stage of 50°C to 70°C may be provided between the initial and later drying stages.

[0065] Preferred coating methods include, for example, reverse coating, spray coating, bar coating, gravure coating, rod coating, die coating, spin coating, extrusion coating, and curtain coating.

[0066] As for the active energy rays, as described in the explanation of the release layer, ultraviolet light is the most preferred.

[0067] The light source for irradiating ultraviolet light is not particularly limited, but for example, ultraviolet fluorescent lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, etc. can be used. ArF excimer lasers, KrF excimer lasers, excimer lamps, or synchrotron radiation can also be used. Of these, ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arcs, xenon arcs, and metal halide lamps are preferred.

[0068] The amount of ultraviolet light irradiated is 50 mJ / cm². ２ The above is preferable, and 100 mJ / cm ２ The above is more preferable, and especially 150 mJ / cm². ２ The above is preferable. The irradiation intensity of ultraviolet light is 2000 mJ / cm². ２ The following is preferable: 1000 mJ / cm ２ The following are preferable.

[0069] It is preferable to perform ultraviolet irradiation in an atmosphere with a low oxygen concentration. This increases the curing efficiency. For example, the oxygen concentration during ultraviolet irradiation is preferably 1,000 ppm or less, more preferably 500 ppm or less, even more preferably 300 ppm or less, and particularly preferably 200 ppm or less.

[0070] A low-oxygen atmosphere can be created, for example, by supplying an inert gas such as nitrogen or argon to the area irradiated with ultraviolet light, or by continuously introducing and filling the ultraviolet irradiation device with an inert gas.

[0071] It is preferable to suppress the temperature rise of the composition when irradiated with ultraviolet light. As a method to suppress this temperature rise, for example, a method can be employed in which the conveying roller of the substrate on which the composition is laminated is equipped with a cooling function or a temperature control function.

[0072] As described above, performing ultraviolet irradiation in a low-oxygen atmosphere and suppressing the temperature rise of the composition during ultraviolet irradiation can be expected to enhance orientation.

[0073] Figure 1 shows an example of a manufacturing apparatus for the release film of the present invention. However, the present invention is not limited thereto.

[0074] In Figure 1, the substrate 10 is unwound from the unwinding device 20 and transported, and an active energy ray curable composition (not shown) is applied by the coating device 30. The solvent in the composition evaporates and dries in the drying device 40, forming a release layer precursor (not shown) on the substrate 10. This release layer precursor is irradiated with ultraviolet light in the ultraviolet irradiation device 50 and hardened to form a release layer, becoming a release film 11, which is then wound into a roll by the winding device 60.

[0075] In the ultraviolet irradiation device 50, the substrate 10 on which the release layer precursor is formed is wound around the transport roller 51 and transported while being irradiated with ultraviolet light from the ultraviolet generator 52. The transport roller 51 is either water-cooled or temperature-controlled to 20-50°C.

[0076] [Adhesive Tape with Release Film] The release film of the present invention is preferably applied to adhesive tape. The above-mentioned adhesive tape refers to a tape in which an adhesive layer is laminated on a support. Examples of support materials include synthetic resin film, paper, cloth, nonwoven fabric, resin foam, and aluminum foil. Examples of adhesives that form the adhesive layer include silicone-based adhesives, acrylic-based adhesives, rubber-based adhesives, silicone-based adhesives, urethane-based adhesives, and polyester-based adhesives. Among these adhesives, silicone-based adhesives are preferably used because they have relatively good weather resistance and chemical resistance, are not sticky, and have the advantage that the adhesive strength does not change much even when reapplied. In other words, the release film of the present invention is preferably applied to silicone adhesive tape.

[0077] Here, an adhesive tape to which a release film is attached is called an adhesive tape with a release film. A preferred embodiment to which the release film of the present invention is applied is a silicone adhesive tape with a release film to which the silicone adhesive layer of a silicone adhesive tape and the release layer of the release film of the present invention are attached opposite each other.

[0078] Furthermore, the release film of the present invention can also be suitably applied to adhesive tapes without a support (supportless adhesive tapes). For example, the release film of the present invention can be applied to one or both sides of a supportless adhesive tape. Specifically, one configuration is to apply the release film of the present invention as a light release film to one side of the supportless adhesive tape, and to apply another release film with a greater peeling force than the release film of the present invention to the other side as a heavy release film. The other release film is not particularly limited, and any known release film can be used. Supportless silicone adhesive tapes are preferred as the supportless adhesive tapes to which the release film of the present invention is applied.

[0079] The release film of the present invention exhibits good release properties with respect to silicone adhesive tape. For example, the release force between the silicone adhesive tape and the release film is preferably 1.5 N / 50 mm or less, more preferably 1.0 N / 50 mm or less, and particularly preferably 0.7 N / 50 mm or less. The lower limit of the release force is preferably 0.1 N / 50 mm or more. The above release forces are those obtained when using "Kapton®" tape No. 650S#25 manufactured by Teraoka Seisakusho Co., Ltd. as the silicone adhesive tape. Details of the measurement method are shown in the examples described later.

[0080] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0081] [Measurement Method and Evaluation Method] (1) Measurement of the average length (RSm) of roughness curve elements The RSm of the release layer was measured in accordance with JIS B0601 (2001) "ISO 4278 (1997)" using an atomic force microscope "AFM5100N" manufactured by Hitachi High-Tech Science under the following conditions. Ten points were measured and averaged. - Scanning mode: DFM - Scanning range: 5 μm × 5 μm - Number of data points: 512 × 512 - Measurement environment: 25°C, in air.

[0082] (2) Measurement of the thickness of the release layer Samples for cross-sectional observation of the release film were prepared using the FIB method with a microsampling system (Hitachi FB-2000A) (specifically, based on the method described on pp. 118-119 of "Polymer Surface Processing" (by Akira Iwamori, published June 2005). The cross-section of the sample for cross-sectional observation was observed using a transmission electron microscope (Hitachi H-9000UHRII) with an acceleration voltage of 300kV, and the thickness of the release layer was measured. Three measurements were taken and averaged.

[0083] (3) Measurement of Surface Free Energy of Substrates Three liquids with known surface free energy and their respective components (dispersion force, polar force, hydrogen bonding force) were used: water, diiodomethane, and 1-bromonaphthalene. At 23°C and 65% RH, the contact angle of each liquid on the substrate was measured using a DropMasterDM501 contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.). Five measurements were taken for each measurement surface, and the average value was taken as the contact angle (θ). From this contact angle (θ) value and the known values ​​for each liquid (Panzer's Method IV (described in the Journal of the Japan Adhesion Society, Vol. 15, No. 3, p. 96)), the values ​​of each component were calculated using the following formula, which is derived from the Kitazaki-Hata formula: (γSd・γLd)¹ / ² + (γSp・γLp)¹ / ² + (γSh・γLh)¹ / ² = γL(¹ + cosθ) / ².

[0084] Here, γLd, γLp, and γLh represent the dispersion force, polar force, and hydrogen bonding force components of the measurement liquid, respectively; θ represents the contact angle of the measurement liquid on the measurement surface; γSd, γSp, and γSh represent the values ​​of the dispersion force, polar force, and hydrogen bonding force components of the layer surface, respectively; and γL represents the surface energy of each liquid. By substituting the known values ​​and θ into the above equation and solving the resulting system of equations, the values ​​of the three components of the measurement surface (release layer surface) were determined.

[0085] The surface free energy (E) was calculated as the sum of the values ​​of the dispersion force component, the polar force component, and the hydrogen bonding force component, as shown in the following formula: E = γSd + γSp + γSh.

[0086] (4) Measurement of the thickness of the substrate The substrate was cut to A4 size, and the thickness was measured at five arbitrary points within the cut sample using a micrometer according to the micrometer method specified in JIS C2151 (2019). The average value of the obtained values ​​was taken as the thickness of the polyester film.

[0087] (5) Measurement of haze value of substrate In accordance with JIS K 7136 (2000), the haze value was measured using a turbidimeter "NDH-4000" manufactured by Nippon Denshoku Industries Co., Ltd. Three measurements were taken and averaged.

[0088] (6) Measurement of the arithmetic mean height Ra of the substrate roughness curve. Measurement was performed using a Surfcom SE500A manufactured by Kosaka Laboratory in accordance with JIS B0601 (2001) "ISO 4278 (1997)" under the following conditions. Ten measurements were taken and averaged. <Measurement conditions> - Needle tip radius: 2 μm - Cutoff: 0.8 mm - Measurement speed: 0.5 mm / sec - Measurement length: 4 mm.

[0089] (7) Measurement of peeling force The release film was cut to a width of 50 mm x length of 70 mm to be used as a measurement sample. Silicone adhesive tape ("Kapton®" tape No. 650S#25 manufactured by Teraoka Seisakusho Co., Ltd.) was attached to the surface of the release layer of this measurement sample by pressing it down with a rubber roller weighing 5 kg and moving it back and forth once. After being left at room temperature (23 ± 2 °C) for 24 hours, the peeling force was measured using a tensile testing machine at a speed of 300 mm / min when the adhesive tape side was pulled off at 180°. Five measurement samples were prepared, and the peeling force of each measurement sample was measured and averaged. Lower peeling force (N / 50 mm) indicates better peelability.

[0090] [Substrate] A polyethylene terephthalate film with a thickness of 50 μm (Toray Industries, Inc.'s "Lumirror®" S28) was used as the substrate. The surface free energy of this film was 50 mN / m, and the arithmetic mean height Ra was 0.1 μm.

[0091] [Composition for forming a release layer] <Active energy ray curable composition p1> 25 parts by mass of polymerizable long-chain alkyl compound (a1) synthesized as described below, 75 parts by mass of dipentaerythritol hexaacrylate (product name "DPHA" by Daicel Cytec Co., Ltd.) as polymerizable compound (c), and 10 parts by mass of photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.) were added, the mixture was heated to 100°C and mixed for 1 hour, and then the mixture was prepared with a mixed solvent (toluene:IPA:cyclohexanone = 6:3:1 (mass ratio)) to a solid content concentration of 4% by mass.

[0092] (Synthesis of polymerizable long-chain alkyl compound (a1)) In a flask equipped with a stirrer and thermometer, 100 parts by mass of 2-hydroxyethyl acrylate (BHEA, manufactured by Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound (d) having a hydroxyl group, 240 parts by mass of diphenylmethane diisocyanate (Millionate MT, manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound (e), and 25 parts by mass of hexadecanol (1-Hexadecanol, manufactured by Tokyo Chemical Industry Co., Ltd.) as a higher alcohol (f) were charged. The mixture was heated to 100°C and maintained at a constant temperature for 7 hours to allow the reaction to proceed. The reaction was terminated after confirming that the isocyanate group had disappeared based on IR measurement.

[0093] <Activated Energy Ray Curable Composition p2> 25 parts by mass of polymerizable long-chain alkyl compound (a2) synthesized as described below, 75 parts by mass of dipentaerythritol hexaacrylate (Daicel Cytec Co., Ltd. trade name "DPHA") as polymerizable compound (c), and 10 parts by mass of photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.) were added, the mixture was heated to 100°C and mixed for 1 hour, and then the mixture was prepared with a mixed solvent (toluene:IPA:cyclohexanone = 6:3:1 (mass ratio)) to a solid content concentration of 4% by mass.

[0094] (Synthesis of polymerizable long-chain alkyl compound (a2)) In a flask equipped with a stirrer and thermometer, 100 parts by mass of 2-hydroxyethyl acrylate (BHEA, manufactured by Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound (d) having a hydroxyl group, 240 parts by mass of diphenylmethane diisocyanate (Millionate MT, manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound (e), and 26 parts by mass of stearyl alcohol (Conol 30SS, manufactured by Shin Nippon Rika Co., Ltd.) as a higher alcohol (f) were charged. The mixture was heated to 100°C and maintained at a constant temperature for 7 hours to allow the reaction to proceed. The reaction was terminated after confirming that the isocyanate group had disappeared based on IR measurement.

[0095] <Activated Energy Ray Curable Composition p3> 15 parts by mass of a polymerizable long-chain alkyl compound (a3) ​​synthesized as described below, 85 parts by mass of dipentaerythritol hexaacrylate (product name "DPHA" from Daicel Cytec Co., Ltd.) as a polymerizable compound (c), and 10 parts by mass of a photopolymerization initiator (Irgacure 184 from Ciba Specialty Chemicals Co., Ltd.) were added, and the mixture was heated to 100°C and mixed for 1 hour to obtain an activated energy ray curable composition. This composition was prepared with a mixed solvent (toluene:IPA:cyclohexanone = 6:3:1 (mass ratio)) to a solid content concentration of 4% by mass.

[0096] (Synthesis of polymerizable long-chain alkyl compound (a3)) In a flask equipped with a stirrer and thermometer, 100 parts by mass of 2-hydroxyethyl acrylate ("BHEA" from Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound (d) having a hydroxyl group, 86 parts by mass of hexamethylene diisocyanate ("HDI" from Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound (e), and 46 parts by mass of stearyl alcohol ("Conol 30SS" from Shin Nippon Rika Co., Ltd.) as a higher alcohol (f) were charged. The mixture was heated to 100°C and maintained at a constant temperature for 7 hours to allow the reaction to proceed. The reaction was terminated after confirming that the isocyanate group had disappeared based on IR measurement.

[0097] <Activated Energy Ray Curable Composition p4> This composition was prepared in the same manner as activated energy ray curable composition p3, except that the polymerizable long-chain alkyl compound (a3) ​​was changed to 5 parts by mass and the polymerizable compound (c) to 95 parts by mass.

[0098] <Activated Energy Ray Curable Composition p5> 10 parts by mass of a non-polymerizable long-chain alkyl compound (b) synthesized as described below, 66 parts by mass of urethane acrylate (UA-306T from Kyoeisha Chemical Co., Ltd.) and 33 parts by mass of tricyclodecanedimethanol acrylate as polymerizable compounds (c), and 3 parts by mass of a photopolymerization initiator (Irgacure 184 from Ciba Specialty Chemicals Co., Ltd.) were mixed in a solvent (toluene:IPA:cyclohexanone = 6:3:1 (mass ratio)) to a solid content concentration of 4% by mass.

[0099] (Synthesis of non-polymerizable long-chain alkyl compound (b)) In a four-necked flask equipped with a stirrer, nitrogen inlet tube, condenser, and rubber septum, 50 parts by mass of octadecyl acrylate were added, followed by 1.2 parts by mass of 2,2'-bipyridine, and the system was purged with nitrogen. Under a nitrogen stream, 0.5 parts by mass of copper bromide was added, and the reaction system was heated to 90°C. 0.6 parts by mass of polymerization initiator (ethyl 2-bromoisobutyrate) was added to start polymerization, and polymerization was carried out at 90°C for 10 hours under a nitrogen stream without adding any solvent. After confirming that the polymerization rate was 85% by weight or more, 33 parts by mass of 2-ethylhexyl acrylate were added via the rubber septum, and the mixture was heated at 110°C for 20 hours.

[0100] In this way, an A-B type diblock polymer was obtained, consisting of an octadecyl acrylate polymer block and a 2-ethylhexyl acrylate polymer block. This was heated to 60°C and centrifuged with an 8,000 g centrifugal force for 30 minutes to obtain the supernatant polymer. 50 parts by mass of this polymer were added to 10 parts by mass of sulfonic acid type ion exchange resin, and the mixture was stirred at 100°C for 1 hour. The ion exchange resin was filtered off to obtain a long-chain alkyl compound (polymer) with a number average molecular weight of 25,000.

[0101] <Activated Energy Ray Curable Composition p6> This composition was prepared in the same manner as composition p3, except that KAYARAD DPCA-120 (trade name of Nippon Kayaku Co., Ltd.) was used as the polymerizable compound (c).

[0102] <Activated Energy Ray Curable Composition p7> This composition was prepared by uniformly mixing 48 parts by mass of octadecyl acrylate as a polymerizable long-chain alkyl compound (a), 72 parts by mass of 2-ethylhexyl acrylate as a polymerizable compound (c), and 10 parts by mass of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals, Inc.) with 28 parts by mass of ethyl acetate.

[0103] <Thermosetting composition q1> - Long-chain alkyl compound: 10 parts by mass in terms of solid content of a mixture of a long-chain alkyl group-containing alkyd resin and a melamine-based crosslinking agent ("Tesfine 303" manufactured by Resona Co., Ltd.) - Acid catalyst c: 0.3 parts by mass of p-toluenesulfonic acid ("TAYCACURE" AC-707 manufactured by Teika Co., Ltd.) in terms of solid content - Solvent: Mixed solvent (toluene:methyl ethyl ketone:cyclohexanone = 45:45:10 (mass ratio)) adjusted to a solid content concentration of 2.0% by mass.

[0104] <Thermosetting composition q2> - Long-chain alkyl compound: 3 parts by mass of long-chain alkyl group-containing polyvinyl resin (Lion Specialty Chemicals Co., Ltd.'s "P-Royl" 1050) on a solid content basis - Crosslinking agent: 70 parts by mass of melamine compound (Mitsui Chemicals, Inc.'s "Uban" 28-60) on a solid content basis - Acid catalyst: 5 parts by mass of p-toluenesulfonic acid (Teika Co., Ltd.'s "TAYCACURE" AC-707) on a solid content basis - Solvent: Mixed solvent (toluene:methyl ethyl ketone:cyclohexanone = 45:45:10 (mass ratio)) adjusted to a solid content concentration of 2.0% by mass.

[0105] <Thermosetting composition q3> - 10 parts by mass of melamine compound (Sanba Research Institute Co., Ltd. "ATOM BOND" RP-50) on a solid content basis - Acid catalyst; 2.0 parts by mass of isocyanate compound (Washin Chemical Industry Co., Ltd. "Plus Coat ST" DEP Clear) on a solid content basis - Solvent; Mixed solvent (toluene:cyclohexanone:methanol = 50:40:10 (mass ratio)) adjusted to a solid content concentration of 5.0% by mass.

[0106] <Thermosetting composition q4> - Silicone compound: 40 parts by mass in terms of solid content of addition reaction-curable silicone resin (KS847H from Shin-Etsu Chemical Co., Ltd.) - Curing agent: 0.4 parts by mass of PL-50T from Shin-Etsu Chemical Co., Ltd. - Solvent: Mixed solvent (toluene:heptane = 1:1 (mass ratio)) adjusted to a solid content concentration of 0.4% by mass.

[0107] [Example 1] A release film was manufactured using the manufacturing apparatus shown in Figure 1. Specifically, an active energy ray curable composition p1 was applied to one side of the substrate using a gravure coater, initial drying was performed at 40°C for about 30 seconds, followed by final drying at 80°C for about 30 seconds, and then ultraviolet light at 300 mJ / cm² in an atmosphere with an oxygen concentration of 100 ppm. ２ Irradiation was performed to form a release layer (film thickness 200 nm) on the substrate.

[0108] [Examples 2-5] Release films were prepared in the same manner as in Example 1, except that the active energy ray curable composition was changed as shown in Table 1.

[0109] [Example 6] A release film was manufactured in the same manner as in Example 1, except that the drying conditions were changed as follows: <Drying conditions> Initial drying was performed at 45°C for about 30 seconds, followed by late drying at 75°C for about 30 seconds.

[0110] [Example 7] A release film was manufactured in the same manner as in Example 1, except that the drying conditions were changed as follows: <Drying conditions> Initial drying was performed at 40°C for about 30 seconds, followed by intermediate drying at 60°C for about 20 seconds, and then final drying at 85°C for about 20 seconds.

[0111] [Comparative Example 1] A release film was manufactured using the manufacturing apparatus shown in Figure 1. Specifically, an active energy ray curable composition p3 was applied to one side of the substrate using a gravure coater, dried at 100°C for about 40 seconds, and then exposed to ultraviolet light at 300 mJ / cm². ２ Irradiation was performed to form a release layer (film thickness 200 nm) on the substrate.

[0112] [Comparative Example 2] A release film was manufactured in the same manner as in Comparative Example 1, except that the drying conditions were changed as follows: <Drying conditions> The film was dried at 70°C for approximately 60 seconds.

[0113] [Comparative Example 3] A release film was manufactured in the same manner as in Comparative Example 2, except that the active energy ray curable composition p6 was used.

[0114] [Comparative Example 4] A release film was manufactured in the same manner as in Comparative Example 1, except that the active energy ray curable composition p7 was used.

[0115] [Comparative Examples 5-6] Using the manufacturing apparatus shown in Figure 1 (without using an ultraviolet irradiation device), thermosetting compositions q1 and q2 were applied to one side of the substrate using a gravure coater, pre-dried at 100°C, and then heated and dried at 160°C for 30 seconds to form a release layer (film thickness 200 nm) on the substrate, thereby producing a release film.

[0116] [Reference Examples 1-2] As conventional release films that do not use long-chain alkyl compounds, the above thermosetting compositions q3 (melamine release) and q4 (silicone-based release) were used to produce a release film by forming a release layer (film thickness 100 nm) on a substrate in the same manner as in Comparative Examples 5-6.

[0117] [Evaluation] The RSm and peel force of the release layer surface were measured for the release film prepared as described above. The results are shown in Table 1.

[0118]

[0119] 10 Substrate 11 Release film 20 Unwinding device 30 Coating device 40 Drying device 50 UV irradiation device 51 Conveyor roller 52 UV generator 60 Winding device

Claims

1. A release film having a release layer on a substrate, wherein the release layer is made of a cured layer of an active energy ray curable composition containing a compound having an alkyl group having 8 or more carbon atoms (hereinafter referred to as a "long-chain alkyl compound"), and the average length (RSm) of the roughness curve elements measured by an atomic force microscope (AFM) on the surface of the release layer is 300 nm or more.

2. The release film according to claim 1, wherein the active energy ray curable composition further contains a compound that does not have an alkyl group having 8 or more carbon atoms in its molecule and has an ethylenically unsaturated group (hereinafter referred to as "polymerizable compound (c)").

3. The release film according to claim 1, wherein the long-chain alkyl compound comprises a compound having an alkyl group with 8 or more carbon atoms and an ethylenically unsaturated group (hereinafter referred to as "polymerizable long-chain alkyl compound (a)").

4. The release film according to claim 2, wherein the polymerizable compound (c) comprises a compound that does not have an alkyl group having 8 or more carbon atoms in its molecule and has 2 to 10 ethylenically unsaturated groups.

5. The release film according to claim 2, wherein the mass ratio of the long-chain alkyl compound to the polymerizable compound (c) (mass of polymerizable compound (c) / mass of long-chain alkyl compound) is 1.7 or more and 15.0 or less.

6. The release film according to claim 2, wherein the total mass of the long-chain alkyl compound and the polymerizable compound (c) is 70% by mass or more with respect to 100% by mass of the total solid content of the active energy ray curable composition.

7. The release film according to claim 1, wherein the thickness of the release layer is 50 nm or more and less than 600 nm.

8. The release film according to claim 1, wherein the base material is a polyester film.

9. The release film according to claim 1, wherein the surface free energy of the surface of the substrate on the release layer side is 40 mN / m or more and 60 mN / m or less.

10. The release film according to claim 1, wherein the arithmetic mean height Ra of the roughness curve of the surface of the substrate on the release layer side is 0.03 μm or more and 0.70 μm or less.

11. A release film adhesive tape comprising a silicone adhesive layer of a silicone adhesive tape to which a release film according to any one of claims 1 to 10 is bonded.

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