Transfer film

Abstract

Provided is a transfer film that suppresses the occurrence of optical unevenness and film deformation. The present invention pertains to a transfer film comprising an active energy ray-curable resin layer peelably layered on a base material, wherein the active energy ray-curable resin layer has, in the infrared spectrum, an IR peak absorbance ratio (T810 / T830) between the absorbance (T810) of an IR peak at 810 cm-1 and the absorbance (T830) of an IR peak at 830 cm-1 of 0.60 to 1.20.

Description

Transfer film

[0001] The present invention relates to a transfer film having an active energy ray-curable resin layer.

[0002] To protect the surface of optically functional films such as polarizing films, phase difference films, and optically anisotropic films, curable resin layers such as hard coat layers and protective layers are laminated. As a method for laminating curable resin layers, a method is known in which optically functional layers such as orientation layers, polarizing layers, anisotropic layers, and phase difference layers are laminated on a curable resin layer formed on a release film (for example, Patent Documents 1 to 3).

[0003] Japanese Patent Publication No. 2018-10086, Japanese Patent Publication No. 2022-117202, Japanese Patent Publication No. 2023-130873

[0004] When an optical functional layer is laminated onto a curable resin layer formed on a release film, components of the optical functional layer may penetrate the curable resin layer, causing optical unevenness. This phenomenon was particularly pronounced when the optical functional layer contained light-absorbing components. Furthermore, when the curing degree of the curable resin layer increased, the transfer film could deform.

[0005] Therefore, in view of the problems of the prior art described above, the object of the present invention is to provide a transfer film in which the occurrence of optical unevenness and deformation of the film are suppressed.

[0006] To solve the above problems, the present invention has the following configuration: [1] A transfer film having an active energy ray curable resin layer peelably laminated on a substrate, wherein the active energy ray curable resin layer has an infrared spectral spectrum of 810 cm⁻¹ －１ Absorbance of the IR peak (T810) and 830 cm －１ A transfer film in which the IR peak absorbance ratio (T810 / T830) of the IR peak absorbance (T830) is 0.60 to 1.20.

[0007] [2] The transfer film according to [1], wherein the thickness of the active energy ray curable resin layer is 0.5 μm or more and 7.0 μm or less.

[0008] [3] The transfer film according to [1] or [2], wherein the substrate has a release layer.

[0009] [4] The transfer film according to any one of [1] to [3], wherein the peeling force between the substrate and the active energy ray curable resin layer is 0.12 N / 25 mm or less.

[0010] [5] The transfer film according to any one of [1] to [4], wherein the active energy ray curable resin layer is a curable resin layer comprising a curable composition, the curable composition comprising a polyfunctional (meth)acrylic polymer and / or a urethane (meth)acrylate oligomer.

[0011] [6] The transfer film according to [5], wherein the curable composition is a curable composition of the following embodiments I or II. <Embodiment I> A curable composition containing 60% by mass or more of a polyfunctional (meth)acrylic polymer based on 100% by mass of the total solid content of the curable composition. <Embodiment II> A curable composition containing 60% by mass or more of a urethane (meth)acrylate oligomer (A) having four or more functional groups based on 100% by mass of the total solid content of the curable composition.

[0012] [7] The transfer film according to [6], wherein the curable composition of embodiment I further contains a urethane (meth)acrylate oligomer (B) having 1 to 3 functional groups.

[0013] [8] The transfer film according to [6], wherein the curable composition of embodiment II further contains a urethane (meth)acrylate oligomer (B) having 1 to 3 functional groups.

[0014] According to the present invention, even when an optical functional layer or the like is laminated, it is possible to provide a transfer film in which the occurrence of optical unevenness and deformation of the film are suppressed.

[0015] This is a schematic side view showing an example of a manufacturing apparatus for the transfer film of the present invention.

[0016] The transfer film of the present invention has an active energy ray curable resin layer that is peelably laminated on a substrate, and the active energy ray curable resin layer exhibits an infrared spectral spectrum of 810 cm⁻¹. －１ Absorbance of the IR peak (T810) and 830 cm －１The IR peak absorbance ratio (T810 / T830) is characterized by being 0.60 to 1.20. Here, wavenumber 810 cm⁻¹ －１ The IR peak is an absorption peak originating from the vinyl group (C=C), at 830 cm⁻¹. －１ The IR peak is a peak derived from (C-H). As the active energy ray curable resin layer hardens, vinyl groups are consumed and T810 decreases, but T830 remains unchanged. That is, T830 is the absorbance of the reference peak, and the ratio of the IR peak absorbance of T810 to T830 (T810 / T830) is one indicator of the degree of hardening. Hereafter, the IR peak absorbance ratio (T810 / T830) may be referred to as the "IR peak absorbance ratio".

[0017] [Active Energy Ray Curable Resin Layer] As the degree of curing of the above active energy ray curable resin layer increases, the IR peak absorbance ratio decreases, and as the degree of curing decreases, the IR peak absorbance ratio increases.

[0018] We found that an IR peak absorbance ratio of 0.60 to 1.20 in the active energy ray-curable resin layer suppresses the occurrence of optical unevenness in the transfer film and the deformation of the film. Furthermore, an IR peak absorbance ratio of 0.60 or higher is advantageous in terms of the flexibility of the active energy ray-curable resin layer. Details of flexibility will be described later.

[0019] From the viewpoint of suppressing the occurrence of optical unevenness, the IR peak absorbance ratio is preferably 1.10 or less, more preferably 1.05 or less, even more preferably 1.00 or less, and particularly preferably 0.95 or less. On the other hand, from the viewpoint of suppressing deformation of the transfer film, the IR peak absorbance ratio is preferably 0.65 or more, more preferably 0.70 or more, even more preferably 0.75 or more, and particularly preferably 0.80 or more.

[0020] The above-mentioned active energy ray-curable resin layer refers to a resin layer cured by irradiation with active energy rays. Specifically, it is a resin layer cured by irradiating an active energy ray-curable resin composition applied to a substrate with active energy rays. Examples of active energy rays include ultraviolet rays, visible light, infrared rays, electron beams, alpha rays, beta rays, and gamma rays. Among these, ultraviolet rays and electron beams are preferred, and ultraviolet rays are particularly preferred. Hereinafter, the active energy ray-curable resin layer may be referred to as the "curable resin layer," and the active energy ray-curable resin composition as the "curable composition."

[0021] Polymerizable Compounds The curable composition for forming the curable resin layer in the present invention contains a compound that polymerizes and hardens when exposed to active energy rays (hereinafter sometimes referred to as a polymerizable compound).

[0022] Examples of polymerizable compounds include compounds (monomers, oligomers, polymers) having at least one ethylenically unsaturated group in the molecule. Here, preferred examples of ethylenically unsaturated groups include acryloyl groups, methacryloyl groups, acryloyloxy groups, methacryloyloxy groups, allyl groups, vinyl groups, etc. In the following description, "...(meth)acrylate" is a general term for "...acrylate" and "...methacrylate," and "(meth)acrylic..." is a general term for "acrylic..." and "methacrylic...."

[0023] Examples of polymerizable compounds include (meth)acrylate monomers, (meth)acrylate oligomers, polyfunctional (meth)acrylic oligomers, or polymers. Hereinafter, polyfunctional (meth)acrylic oligomers or polymers will be collectively referred to as "polyfunctional (meth)acrylic polymers."

[0024] (Meth)acrylate monomers Preferably, the (meth)acrylate monomers are polyfunctional acrylates having two or more ethylenically unsaturated groups in one molecule. Specific examples include 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, and polypropylene glycol di(meth)acrylate. Monomers such as trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be used. These monomers can be used individually or in combination of two or more.

[0025] (Meth)acrylate oligomers Examples of the above (meth)acrylate oligomers include polyol (meth)acrylate oligomers, polyester (meth)acrylate oligomers, urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, etc. Among these, urethane (meth)acrylate oligomers are preferably used.

[0026] The urethane (meth)acrylate oligomer is preferably one that has 1 to 20 ethylenically unsaturated groups per molecule, more preferably one that has 2 to 15 groups, and particularly preferably one that has 2 to 10 groups. The weight-average molecular weight (Mw) of the urethane (meth)acrylate oligomer is preferably 500 to 30,000, and more preferably 1,000 to 20,000.

[0027] The above-mentioned urethane (meth)acrylate oligomers are generally commercially available, and these commercially available products can be used. Examples of commercially available products include Shin Nakamura Chemical Industry Co., Ltd.'s "NK Oligo (registered trademark)" U-4HA, U-6HA, U-6LPA, U-324A, U-200PA, UA-10HA, UA-32P, UA-33H, UA-4200, UA-7100, UA-1100H, Nippon Kayaku Co., Ltd.'s UX-0937, UX-3204, UX-4101, UXF-4200, UXF-4001-M35, and Kyoeisha Chemical Co., Ltd.'s AH- 600, UA-306H, UA-306T, UA-306I, UA-510H, UF-A01P, UF-B01P, UF-B01X, UF-B01T, UF-07DF, Daiichi Kogyo Seiyaku Co., Ltd.'s "New Frontier (registered trademark)" RST-402, RST-201, R-1235, R-1220, R-1214, R-1304, Nippon Synthetic Chemical Co., Ltd.'s "Shiko (registered trademark)" UV1700B, UV- 2000B, UV2750B, UB3000B, UV3200B, UV-3210EA, UV-3300B, UV-3310B, UV-3500BA, UV-3520EA, UV-3700B, UV-6640B, UV-7650B, Negami Kogyo Co., Ltd.'s "Art Resin (registered trademark)" UN-6200, UN-6202, UN-6300, UN-6301, UN-7600, UN-7700, Daicel Saite Examples include EBECRYL® 204, 205, 230, 264, 265, 270, 1259, 4820, 8311, 8402, 8465, 8701, and 9260 from EC Corporation, KRM® 8296, 8667, 8528, 9465, and 9556 from KRM Corporation, and Miramer® PU240, PU340, and PU610 from Toyo Chemicals Co., Ltd.

[0028] The above-mentioned urethane (meth)acrylate oligomer is preferably a compound having multiple ethylenically unsaturated groups, obtained by reacting (a) a polyol, (b) a polyisocyanate, and (c) a (meth)acrylic acid ester having a hydroxyl group.

[0029] (a) Polyols Examples of the above (a) polyols include polyester polyols, polyether polyols, polycarbonate polyols, aliphatic hydrocarbon polyols, and alicyclic hydrocarbon polyols. These polyols may be used alone or in combination of two or more. The polyols preferably have a number average molecular weight of 200 to 3000 and 2 to 4 hydroxyl groups.

[0030] (a-1) Polyester polyols Examples of the above polyester polyols include condensation polymers of polyhydric alcohols and polyhydric carboxylic acids, ring-opening polymers of cyclic esters (lactones), or reaction products of three components: polyhydric alcohols, polyhydric carboxylic acids, and cyclic esters.

[0031] Examples of the polyhydric alcohols mentioned above include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, tetramethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, methanetriol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, pentaerythritol, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), and sugar alcohols (such as xylitol and sorbitol).

[0032] Examples of the polycarboxylic acids mentioned above include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid.

[0033] Examples of cyclic esters (lactones) include γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

[0034] (a-2) Polyether polyols Examples of the above polyether polyols include polyether polyols obtained by dehydration condensation of a polyhydric alcohol used as a raw material, which contain three or more hydroxyl groups at the molecular ends (side chains).

[0035] Examples of the polyether polyols mentioned above include low molecular weight polyols such as methanetriol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, and pentaerythritol, as well as polyols with three or more functions (three or more hydroxyl groups), such as polyoxyalkylene polyols which are alkylene oxide adducts of these low molecular weight polyols.

[0036] (a-3) Polycarbonate polyols Examples of the above polycarbonate polyols include a reaction product of a polyol and phosgene, in which the polyol is selected to contain three or more hydroxyl groups; and a ring-opening polymer of a cyclic carbonate (such as alkylene carbonate) that contains three or more hydroxyl groups.

[0037] Examples of the polycarbonate polyol include polyols having a low molecular weight (preferably a molecular weight of 64 to 250) such as methanetriol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6 - hexanetriol, pentaerythritol, etc., and polyols having three or more functional groups such as polyoxyalkylene polyols which are alkylene oxide adducts of these polyhydric alcohols.

[0038] (a - 4) Aliphatic hydrocarbon - based polyol Examples of the aliphatic hydrocarbon - based polyol include polyolefin polyols, hydrogenated polybutadiene polyols, etc. The polyolefin polyol may be any one having a total of three or more hydroxy groups at the molecular terminals (side chains) of a hydrocarbon skeleton having at least one branched structure. The hydrogenated polybutadiene polyol may be any one having a structure in which all of the ethylenically unsaturated groups contained in the structure of the polybutadiene polyol are hydrogenated and having a total of three or more hydroxy groups at its molecular terminals (side chains).

[0039] (b) Polyisocyanate Examples of the polyisocyanate include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates. The polyisocyanate preferably has 2 to 4 isocyanate groups.

[0040] Examples of the aliphatic polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4 - trimethylhexamethylene diisocyanate, 2,4,4 - trimethylhexamethylene diisocyanate, lysine diisocyanate, 2 - methylpentane - 1,5 - diisocyanate, 3 - methylpentane - 1,5 - diisocyanate, etc.

[0041] Examples of the alicyclic polyisocyanate include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and the like.

[0042] Examples of the aromatic polyisocyanate include tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and the like.

[0043] Examples of the aromatic aliphatic polyisocyanate include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α,α,α,α-tetramethylxylylene diisocyanate, and the like. Further, examples of the polyisocyanate also include modified products such as dimers, trimers of the polyisocyanates mentioned above, and buretted isocyanate.

[0044] (c) Hydroxy group-containing (meth)acrylic acid esters Examples of the above hydroxy group-containing (meth)acrylic acid esters include (meth)acrylic acid esters of C1 to C8 alcohols having a hydroxy group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and caprolactone-modified 2-hydroxyethyl (meth)acrylate; polyethylene glycol mono(meth)acrylic acid ester, polypropylene glycol mono(meth)acrylic acid ester, polybutylene glycol mono(meth)acrylic acid ester, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, phenylglycidyl ether (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and caprolactone-modified dipentaerythritol penta(meth)acrylate. These (meth)acrylic acid esters having hydroxyl groups may be used individually or in combination of two or more.

[0045] Polyfunctional (meth)acrylic polymer The above polyfunctional (meth)acrylic polymer is a polymer that contains (meth)acrylate monomers as constituent units, but may also contain monomers other than (meth)acrylate monomers as constituent units. The polyfunctional (meth)acrylic polymer has two or more ethylenically unsaturated groups in one molecule. The number of ethylenically unsaturated groups in one molecule of the polymer is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, and particularly preferably 30 or more. Furthermore, the number of ethylenically unsaturated groups is preferably 300 or less, more preferably 200 or less, even more preferably 150 or less, and particularly preferably 100 or less.

[0046] The above-mentioned polyfunctional (meth)acrylic polymer preferably has a weight-average molecular weight (Mw) of 1,000 or more, more preferably 3,000 or more, even more preferably 5,000 or more, and particularly preferably 10,000 or more. Furthermore, the above-mentioned weight-average molecular weight is preferably 300,000 or less, more preferably 200,000 or less, even more preferably 100,000 or less, and particularly preferably 50,000 or less.

[0047] The above-mentioned polyfunctional (meth)acrylic polymers are generally commercially available, and these commercially available products can be used. Examples of commercially available products include SMP-220A, SMP-250AP, SMP-360AP, ​​SMP-550AP from Kyoeisha Chemical Co., Ltd., "Unidic®" V-6840, V-6841, V-6850, RC29-120, EKC-1054, WHV-649, EKS-675 from DIC Corporation, STAR-501, Viscoat #1000 from Osaka Organic Synthesis Chemical Co., Ltd., "Hitaloid®" 7975, 7975D, 7977, 7988 from Hitachi Chemical Co., Ltd., and "Acrit®" 8KX-01, 8KX-012C from Taisei Fine Chemical Co., Ltd. Examples include 8KX-014C, 8KX-018C, 8KX-052C, 8KX-056C, 8KX-058, 8KX-077, 8KX-078, 8KX-089, 8KX-212, Negami Kogyo Co., Ltd.'s "Art Cure (registered trademark)" RA-331P, RA-341, RA-3969MP, RA-3960PG, RA-3602MI, OAP-5000, OAP-2511, AHC-9202MI80, RA-3704MB, RA-3953MP, RA-4101, MAP-702, MAP2801, MAP-4000, MAP-4050, MAP-7000, and others.

[0048] Curable Composition The above curable composition preferably contains a photopolymerization initiator. From the viewpoint of curability, alkylphenone compounds are preferred as the photopolymerization initiator. Specific examples of alkylphenone compounds include 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl-1-(4-methylthiophenyl)2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-phenyl)-1-butane, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-phenyl)-1-butane, and 2-benzyl-2-dimethylamino-1-(4-methylphenyl)methyl Examples include 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butane, 1-cyclohexylphenyl ketone, 2-methyl-1-phenylpropan-1-one, 1-[4-(2-ethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis(2-phenyl-2-oxoacetic acid)oxybisethylene, and high molecular weight versions of these materials.

[0049] The content of the above-mentioned photopolymerization initiator is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass, and particularly preferably 1 to 5% by mass, based on 100% by mass of the total solid content of the curable composition.

[0050] The above curable composition preferably contains a leveling agent. Examples of leveling agents include acrylic, silicone, and fluorine-based leveling agents. By using a leveling agent, improved release properties between the resin layer and the substrate film can be expected. The leveling agent content is preferably 0.1 to 5% by mass, more preferably 0.3 to 5% by mass, and particularly preferably 0.5 to 3% by mass, based on 100% by mass of the total solid content of the curable composition.

[0051] The above-mentioned curable composition may contain non-polymerizable polymers and various additives, such as particles, antioxidants, UV absorbers, and antistatic agents, to the extent that they do not impair the effects of the present invention.

[0052] The above curable composition preferably contains a polyfunctional (meth)acrylic polymer and / or a urethane (meth)acrylate oligomer as a polymerizable compound.

[0053] The following are examples of preferred embodiments, but the present invention is not limited to these. Hereinafter, the number of ethylenically unsaturated groups contained in one molecule of the compound will be referred to as the number of functional groups.

[0054] (Aspect I) Aspect I is an embodiment in which a polyfunctional (meth)acrylic polymer is contained in an amount of 60% by mass or more relative to 100% by mass of the total solid content of the curable composition. The content of the polyfunctional (meth)acrylic polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, relative to 100% by mass of the total solid content of the curable composition. The upper limit is 100% by mass. Among the polyfunctional (meth)acrylic polymers described above, those with 7 or more functional groups are preferred, and those with 10 or more functional groups are more preferred.

[0055] In embodiment I, it is preferable to further contain a urethane (meth)acrylate oligomer having 1 to 3 functional groups. Hereinafter, a urethane (meth)acrylate oligomer having 1 to 3 functional groups will be referred to as "urethane (meth)acrylate oligomer (B)".

[0056] The number of functional groups in the above-mentioned urethane (meth)acrylate oligomer (B) is more preferably 2 to 3. The weight-average molecular weight of the urethane (meth)acrylate oligomer (B) is preferably 4,000 or more, more preferably 6,000 or more, and particularly preferably 8,000 or more. Furthermore, the weight-average molecular weight is preferably 30,000 or less, more preferably 25,000 or less, and particularly preferably 20,000 or less. When using the urethane (meth)acrylate oligomer (B), the amount used is preferably 1 to 40 parts by mass, more preferably 2 to 30 parts by mass, even more preferably 3 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, per 100 parts by mass of the polyfunctional (meth)acrylic polymer.

[0057] (Aspect II) Aspect II includes a feature in which the curable composition contains 60% by mass or more of a urethane (meth)acrylate oligomer having four or more functional groups, based on 100% by mass of the total solid content. Hereinafter, a urethane (meth)acrylate oligomer having four or more functional groups will be referred to as "urethane (meth)acrylate oligomer (A)".

[0058] The number of functional groups of the above urethane (meth)acrylate oligomer (A) is preferably 4 to 20, more preferably 4 to 15, and particularly preferably 5 to 10. The weight-average molecular weight of the urethane (meth)acrylate oligomer (A) is preferably 500 or more, more preferably 700 or more, and particularly preferably 1,000 or more. Furthermore, the weight-average molecular weight is preferably 7,000 or less, more preferably 5,000 or less, and particularly preferably 3,000 or less. The content of the urethane (meth)acrylate oligomer (A) is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the total solid content of the curable composition. The upper limit is 100% by mass.

[0059] In embodiment II, it is preferable to further contain the above-mentioned urethane (meth)acrylate oligomer (B).

[0060] In embodiment II, when urethane (meth)acrylate oligomer (B) is used, its content is preferably 1 to 40 parts by mass, more preferably 2 to 30 parts by mass, even more preferably 3 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, per 100 parts by mass of urethane (meth)acrylate oligomer (A).

[0061] Embodiments I and II described above may or may not contain (meth)acrylate monomer as a polymerizable compound. When (meth)acrylate monomer is included, the content is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass, and particularly preferably 1% by mass or less, based on 100% by mass of the total solid content of the curable composition.

[0062] The curable resin layers made from the curable compositions of Embodiments I and II exhibit good flexibility. Here, flexibility is a characteristic that represents the degree to which cracks occur when the curable resin layer is bent. Good flexibility means that cracks are less likely to occur when the curable resin layer is bent. Flexibility can be measured by a flexibility test using the cylindrical mandrel method. Details of the measurement method are described in the Examples section. The curable resin layer made from the curable composition of Embodiment II exhibits superior flexibility.

[0063] Curable resin layer The curable resin layer is formed by irradiating a curable composition applied to a substrate with active energy rays. The curable resin layer has a degree of curing in a specific range where the IR peak absorbance ratio is 0.60 to 1.20.

[0064] The above-mentioned curable resin layer can be obtained, for example, by controlling the irradiation conditions of the active energy ray. An example in which ultraviolet light is used as the active energy ray will be described below, but the present invention is not limited thereto.

[0065] The cumulative amount of ultraviolet light is 250–450 mJ / cm². ２ It is preferable to adjust the oxygen concentration within this range. Since curing by ultraviolet irradiation can be inhibited by oxygen, it is preferable to adjust the oxygen concentration during ultraviolet irradiation. The oxygen concentration 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. An inert gas purging method such as nitrogen or argon can be used to adjust the oxygen concentration.

[0066] 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.

[0067] The thickness of the curable resin layer is preferably 0.5 to 7.0 μm, more preferably 1 to 5.0 μm, and particularly preferably 1.5 to 4.0 μm.

[0068] [Substrate] The substrate in the present invention is not particularly limited, and paper, synthetic paper, or synthetic resin film can be used. Among these, synthetic resin film is preferred, and a film made of thermoplastic resin is even more preferred.

[0069] Examples of the thermoplastic resins mentioned above include polyolefin resins such as polyethylene, polypropylene, polystyrene, and polymethylpentene; alicyclic polyolefin resins; polyamide resins such as nylon 6 and nylon 66; aramid resins; polyimide resins; polyester resins; polycarbonate resins; polyarylate resins; polyacetal resins; polyphenylene sulfide resins; fluororesins such as tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloride resin, tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride resin; acrylic resins; methacrylic resins; polyacetal resins; polyglycolic acid resins; and polylactic acid resins. Among these, polyester resins, polycarbonate resins, acrylic resins, and methacrylic resins are preferred from the viewpoint of stretchability, conformability, strength, and heat resistance, with polyester resins being more preferred.

[0070] Polyester resins are a general term for polymers whose main chain is an ester bond, and are obtained by polycondensation of an acid component and its ester with a diol component. Specific examples include polyethylene terephthalate, polypropylene terephthalate, polyethylene-2,6-naphthalate, and polybutylene terephthalate. These may also be copolymerized with other dicarboxylic acids and their esters or diol components as the acid or diol components. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalate are more preferred in terms of transparency, dimensional stability, and heat resistance, with polyethylene terephthalate being particularly preferred.

[0071] The above-mentioned substrate may be a single layer or a multi-layered structure. In the case of a multi-layered structure, the resins of each layer may be the same or different.

[0072] The above-mentioned substrate may contain various additives, such as antioxidants, antistatic agents, nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and doping agents for refractive index adjustment. The substrate film may have either a single-layer or laminated structure.

[0073] In this invention, the substrate is ultimately peeled off from the curable resin layer. In other words, the substrate and the curable resin layer are laminated in a peelable manner. Here, one indicator of peelability is the peeling force between the substrate and the curable resin layer.

[0074] The transfer film of the present invention preferably has a peel force of 0.12 N / 25 mm or less between the substrate and the curable resin layer, more preferably 0.10 N / 25 mm or less, and particularly preferably 0.07 N / 25 mm or less. On the other hand, if the above peel force is too low, the substrate and the curable resin layer may peel off during the manufacturing or processing of the transfer film, so the above peel force is preferably 0.01 N / 25 mm or more, more preferably 0.02 N / 25 mm or more, and particularly preferably 0.03 N / 25 mm or more.

[0075] If the peelability between the substrate and the curable resin layer is good, the curable resin layer may be directly laminated onto the substrate. To improve the peelability, it is preferable that the substrate has a release layer. The release layer is part of the substrate and is ultimately peeled off together with the substrate from the curable resin layer.

[0076] In the present invention, it is preferable that the transfer film has a release layer on a substrate having a release layer, and a curable resin layer is laminated on the release layer.

[0077] The release agent constituting the above-mentioned release layer is not particularly limited, and known release agents can be used. Examples include alkyd resins, polyolefin resins, long-chain alkyl group-containing resins, fluororesins, silicone resins, melamine resins, and mixtures or copolymers of organic and silicone resins. Among these, a mixture of melamine resin and silicone resin is more preferred.

[0078] The thickness of the release layer is preferably 0.1 to 3.0 μm, more preferably 0.2 to 2.0 μm, and particularly preferably 0.3 to 1.0 μm.

[0079] The thickness of the above-mentioned substrate is preferably 10 to 100 μm, more preferably 20 to 70 μm, even more preferably 25 to 50 μm, and particularly preferably 35 to 45 μm. Here, if the substrate has a release layer, the thickness of the substrate refers to the total thickness of the substrate and the release layer.

[0080] [Method for manufacturing transfer film] The transfer film of the present invention is preferably obtained by applying a curable composition onto a substrate, drying it, irradiating it with active energy rays, curing it, and forming a curable resin layer.

[0081] In the present invention, when applying the curable composition onto a substrate, it is preferable that the curable composition is adjusted with an organic solvent so that the solid content concentration is 5 to 40% by mass. The above solid content concentration is more preferably 7 to 35% by mass, and particularly preferably 10 to 30% by mass.

[0082] As the above-mentioned organic solvents, for example, alcohol-based solvents such as ethanol, isopropanol, butanol, and isobutanol; aromatic hydrocarbon-based solvents such as toluene and xylene; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and ester-based solvents such as ethyl acetate, propyl acetate, isobutyl acetate, and butyl acetate can be preferably used individually or in combination.

[0083] 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.

[0084] The drying temperature is preferably in the range of 60 to 150°C, more preferably in the range of 70 to 120°C, and particularly preferably in the range of 80 to 110°C. Furthermore, it is preferable to change the drying temperature in stages. For example, it is preferable to dry at a relatively low temperature in the initial drying stage and at a relatively high temperature in the later drying stage.

[0085] It is preferable that the precursor of the curable resin layer, which is applied to a substrate and dried, is cured by irradiation with active energy rays (ultraviolet light) to form a curable resin. The irradiation conditions for ultraviolet light are preferably as described above. The low oxygen concentration atmosphere during ultraviolet irradiation is preferably created, for example, by supplying an inert gas such as nitrogen gas or argon gas to the area irradiated with ultraviolet light, or by constantly introducing and filling the ultraviolet irradiation device with an inert gas.

[0086] Furthermore, it is preferable to suppress the temperature rise of the curable resin layer precursor during ultraviolet irradiation. As a method for suppressing the temperature rise, for example, a method of providing a cooling function or a temperature control function to the conveying roller of the substrate on which the curable resin layer precursor is formed can be preferably employed.

[0087] Figure 1 shows an example of a transfer film manufacturing apparatus according to the present invention. However, the present invention is not limited thereto.

[0088] The substrate 10 is unwound from the unwinding device 20 and transported, a curable composition (not shown) is applied by the coating device 30, and the solvent in the composition evaporates and dries in the drying device 40 to form a curable resin layer precursor (not shown) on the substrate 10. This curable resin layer precursor is irradiated with ultraviolet light in the ultraviolet irradiation device 50 to cure and form a curable resin layer, becoming a transfer film 11, which is then wound into a roll by the winding device 60.

[0089] In the ultraviolet irradiation device 50, the substrate 10 on which the precursor of the curable resin layer has been formed is wound around a conveyor roller 51 and conveyed while being irradiated with ultraviolet light from an ultraviolet generator 52. The conveyor roller is either water-cooled or temperature-controlled to 20-50°C.

[0090] [Use] The transfer film of the present invention can be used, for example, for surface protection of molded bodies made of plastics or metals.

[0091] The transfer film of the present invention has a curable resin layer laminated on a substrate in a peelable manner, and this curable resin layer is transferred to the object to be transferred. The curable resin layer transferred to the object to be transferred functions as a surface protection layer of the object to be transferred. After the curable resin layer of the transfer film is transferred to the object to be transferred, the substrate of the transfer film is peeled off.

[0092] The transfer film of the present invention is suitable for surface protection of optical functional films such as polarizing films, retardation films, and optically anisotropic films. Specifically, the curable resin layer of the transfer film of the present invention is suitable as a protective layer for optical functional layers such as alignment layers, polarizing layers, anisotropic layers, and retardation layers. In this form, a method of peeling the substrate after laminating the above optical functional layer on the curable resin layer of the transfer film of the present invention may be adopted.

[0093] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited only to these examples.

[0094] [Measurement method and evaluation method] (1) Measurement of the IR peak absorbance ratio of the curable resin layer For the transfer film, using an ALPHA device ATR-FT-IR manufactured by BRUKER, the absorbance was measured by the ATR-FTIR method. The measurement was carried out at a position 1 to 2 μm from the surface of the curable resin layer toward the substrate direction, with a wave number range of 400 to 4000 cm －１ , a resolution of 4 cm －１ , and 16 scan times. From the obtained infrared absorption spectrum, the absorbances at the IR peaks of wave number 810 cm －１ and wave number 830 cm －１ were respectively obtained, and the IR peak absorbance ratio (T810 / T830) was calculated.

[0095] (2) Measurement of peeling force between substrate and curable resin layer For the transfer film, one side of an adhesive film (Panaclean PD-S1 25 μm product from Panac Co., Ltd.), with one separator removed, was bonded to the surface of the curable resin layer of the transfer film without introducing air bubbles. Then, the separator of the adhesive film was peeled off and attached to a PET film (188 μm Toray Industries, Inc. "Lumirror®" T60) to prepare a sample for measurement.

[0096] After cutting the above-mentioned sample for measurement into a width of 25 mm, a 180-degree peel was performed between the substrate and the curable resin layer using a universal tensile tester (Intesco, model: 200X) at a test speed of 300 mm / min, and the peel force (N / 25 mm) was measured.

[0097] (3) Evaluation of optical unevenness in the curable resin layer The entire surface of the curable resin layer of a test piece cut from a transfer film into a 100 mm square was painted with an oil-based black pen (model number: MC-EB-450, manufactured by Zebra), heated at 150°C for 3 minutes, and then immersed in room temperature ethanol solution for 10 seconds to remove the black ink adhering to the surface. After removing from the ethanol solution, the ethanol on the surface was lightly wiped off. The surface of the test piece obtained in this way was observed, and optical unevenness due to the penetration of black ink was visually observed and evaluated according to the following criteria. A: No optical unevenness can be observed. B: Slight optical unevenness can be observed in some areas. C: Dark optical unevenness can be observed over the entire surface.

[0098] (4) Evaluation of deformation of the transfer film A test piece cut from the transfer film into a 200 mm square was placed on a horizontal surface with the curable resin layer facing upwards, and the number of wavy irregularities was visually observed and evaluated according to the following criteria: A: No wavy irregularities were observed. B: One or two wavy irregularities were observed. C: Three or more wavy irregularities were observed.

[0099] (5) Flexibility test using the cylindrical mandrel method In accordance with the cylindrical mandrel method (JIS K5600-5-1:1999), the transfer film was wrapped around a cylindrical mandrel with a diameter of 2 mm to 5 mm with the curable resin layer facing outwards. The curable resin layer was visually inspected to see if cracks occurred, and the minimum diameter of the mandrel in which no cracks occurred was confirmed. The following criteria were used for evaluation: A: Minimum diameter 2 mm (no cracks occur at a diameter of 2 mm) B: Minimum diameter 3 mm (cracks occur at a diameter of 2 mm, but not at a diameter of 3 mm) C: Minimum diameter 4 mm (cracks occur at a diameter of 3 mm, but not at a diameter of 4 mm) D: Minimum diameter 5 mm (cracks occur at a diameter of 4 mm, but not at a diameter of 5 mm) E: Minimum diameter greater than 5 mm (cracks occur at a diameter of 5 mm).

[0100] [Example 1] As a base material, a polyester film with a thickness of 38 μm (product name "Lumirror®" R75X, manufactured by Toray Industries, Inc.) was prepared, having the following release layer (thickness 0.4 μm).

[0101] <Release Layer> The release layer coating liquid described below was applied to the polyester film and dried and cured at 120°C to form a release layer.

[0102] <Release Layer Coating Solution> The following materials were mixed and diluted with a methyl ethyl ketone / isopropyl alcohol mixed solvent (mass mixing ratio 50 / 50) to obtain a release layer coating solution with a solid content concentration of 5% by mass. ・One-ended carbinol-modified reactive silicone oil (X-22-170DX Shin-Etsu Chemical Co., Ltd., solid content concentration 100% by mass): 1 part by mass ・Both-ended polyether-modified reactive silicone oil (X-22-4952 Shin-Etsu Chemical Co., Ltd., solid content concentration 100% by mass): 5 parts by mass ・Acrylic-modified alkyd resin (Halifthal KV-905 Harima Chemicals Co., Ltd., solid content concentration 53% by mass): 100 parts by mass ・Isobutyl alcohol-modified melamine resin (Melan 2650L Hitachi Chemical Co., Ltd., solid content concentration 60% by mass): 20 parts by mass ・Paratoluenesulfonic acid: 5 parts by mass.

[0103] <Formation of Curable Resin Layer> On the release layer of the substrate with the release layer prepared above, the following curable composition 1 is applied using a slot die coater, dried at 80°C for 30 seconds, and then subjected to an integrated light intensity of 250 mJ / cm² under an atmosphere of oxygen concentration of 100 ppm by nitrogen purging. ２ A curable resin layer (2.5 μm thick) was formed by irradiating it with ultraviolet light.

[0104] <Curable Composition 1> The following components were dissolved in methyl ethyl ketone to obtain curable composition 1 with a solid content concentration of 20% by mass. • Polyfunctional acrylic polymer: DIC Corporation's "UNIDIC®" V-6850: 90 parts by mass • Urethane acrylate oligomer (B): Daicel Cytec Corporation's "EBECRYL®" 230 (number of functional groups: 2-functional, Mw: 5,000): 10 parts by mass • Leveling agent: LINC-3A (Kyoeisha Chemical Co., Ltd.): 1 part by mass • Photopolymerization initiator: α-hydroxyacetophenone type photopolymerization initiator ("Omnirad®" 184 (manufactured by IGM)): 3 parts by mass.

[0105] [Examples 2-6 and Comparative Examples 1-4] In Example 1, a curable resin layer was formed in the same manner as in Example 1, except that the integrated amount of ultraviolet light and the oxygen concentration were changed as shown in Table 1. In Comparative Examples 3 and 4, ultraviolet irradiation was carried out in the atmosphere (without nitrogen purging).

[0106] [Evaluation] The transfer films prepared in the above examples and comparative examples were measured and evaluated for IR peak absorbance ratio, peel strength, optical uniformity, transfer film deformation, and mandrel flexibility. The results are shown in Table 1.

[0107]

[0108] [Examples 11-16 and Comparative Examples 11-14] Transfer films were prepared in the same manner as in Examples 1-6 and Comparative Examples 1-4, except that the curable composition was changed to curable composition 2 described below.

[0109] <Curable Composition 2> The following components were dissolved in methyl ethyl ketone to obtain curable composition 2 with a solid content concentration of 20% by mass. • Polyfunctional acrylic polymer: "Acrit®" 8KX-078 from Taisei Fine Chemical Co., Ltd. (number of functional groups: 166, Mw: 40,000): 95 parts by mass • Urethane acrylate oligomer (B): "KRM®" 9465 from Daicel Cytec Co., Ltd. (number of functional groups: 2-functional, Mw: 10,000): 5 parts by mass • Leveling agent: LINC-3A (Kyoeisha Chemical Co., Ltd.): 1 part by mass • Photopolymerization initiator: α-hydroxyacetophenone type photopolymerization initiator ("Omnirad®" 184 (manufactured by IGM)): 3 parts by mass.

[0110] [Evaluation] The transfer films prepared in the above examples and comparative examples were measured and evaluated for IR peak absorbance ratio, peel strength, optical uniformity, transfer film deformation, and mandrel flexibility. The results are shown in Table 2.

[0111]

[0112] [Examples 21-26 and Comparative Examples 21-24] Transfer films were prepared in the same manner as in Examples 1-6 and Comparative Examples 1-4, except that the curable composition was changed to curable composition 3 described below.

[0113] <Curable Composition 3> The following components were mixed and dissolved in methyl ethyl ketone to obtain curable composition 3 with a solid content concentration of 20% by mass. • Urethane acrylate oligomer (A): "Miramer®" PU610 (6 functional groups, Mw 1,800) from Toyo Chemicals Co., Ltd.: 90 parts by mass • Urethane acrylate oligomer (B): "KRM®" 9556 (2 functional groups, Mw 8,000) from Daicel Cytec Co., Ltd.: 10 parts by mass • Leveling agent: LINC-3A (Kyoeisha Chemical Co., Ltd.): 1 part by mass • Photopolymerization initiator: α-hydroxyacetophenone type photopolymerization initiator ("Omnirad®" 184 (manufactured by IGM)): 3 parts by mass.

[0114] [Evaluation] The transfer films prepared in the above examples and comparative examples were measured and evaluated for IR peak absorbance ratio, peel strength, optical uniformity, transfer film deformation, and mandrel flexibility. The results are shown in Table 3.

[0115]

[0116] [Examples 31-36 and Comparative Examples 31-34] Transfer films were prepared in the same manner as in Examples 1-6 and Comparative Examples 1-4, except that the curable composition was changed to curable composition 4 described below.

[0117] <Curable Composition 4> Using urethane acrylate oligomers A1 and B1 synthesized as described below, the following components were dissolved in methyl ethyl ketone to obtain curable composition 4 with a solid content concentration of 20% by mass. • Urethane acrylate oligomer A1 (5 functional groups, Mw 1,200): 95 parts by mass • Urethane acrylate oligomer B1 (2 functional groups, Mw 14,000): 5 parts by mass • Leveling agent: LINC-3A (Kyoeisha Chemical Co., Ltd.): 1 part by mass • Photopolymerization initiator: α-hydroxyacetophenone type photopolymerization initiator ("Omnirad®" 184 (manufactured by IGM)): 3 parts by mass.

[0118] <Synthesis of Urethane Acrylate Oligomer A1> 108 parts by mass of bisphenol A type diepoxy resin (YD-8125, manufactured by Nippon Steel Chemical Co., Ltd.), 45 parts by mass of acrylic acid as a (meth)acrylic acid derivative, 0.2 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor, and 0.8 parts by mass of dimethylaminoethyl methacrylate as a catalyst were added. The mixture was heated to 95°C while stirring, and the reaction was continued at 95°C for 14 hours. The first stage of the reaction was terminated when the acid value became 1 mg KOH / g or less, yielding an epoxy acrylate having two hydroxyl groups.

[0119] Next, after lowering the temperature to 60°C, ethyl acetate was added as a diluent, and 0.03 parts by mass of di-n-butyltin dilaurate was added as a catalyst. While stirring, 83 parts by mass of dicyclohexylmethane diisocyanate was added dropwise over 2 hours, followed by 94 parts by mass of pentaerythritol triacrylate being added dropwise over 1 hour. The reaction was continued for 5 hours after the addition of the drops to obtain pentafunctional urethane acrylate oligomer A1 with a weight-average molecular weight of 1200.

[0120] <Synthesis of Urethane Acrylate Oligomer B1> Ethyl acetate was added to 70 parts by mass of polytetramethylene glycol (PTMG1000, manufactured by Mitsubishi Chemical Corporation) and 33 parts by mass of polyoxyethylene bisphenol A ether (Newpol BPE-40, manufactured by Sanyo Chemical Industries, Ltd.), and the mixture was heated to an internal temperature of 60°C. 0.03 parts by mass of di-n-butyltin dilaurate was added as a synthesis catalyst, and 31 parts by mass of isophorone diisocyanate was added dropwise over 1 hour while stirring. The reaction was continued for 2 hours after the completion of the dropwise addition. Subsequently, 2.4 parts by mass of 2-hydroxyethyl acrylate was added dropwise over 1 hour. The reaction was continued for 5 hours after the dropwise addition to obtain a bifunctional urethane acrylate oligomer B1 with a weight-average molecular weight of 14,000.

[0121] [Evaluation] The transfer films prepared in the above examples and comparative examples were measured and evaluated for IR peak absorbance ratio, peel strength, optical uniformity, transfer film deformation, and mandrel flexibility. The results are shown in Table 4.

[0122]

[0123] 10 Substrate 11 Transfer 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 transfer film having an active energy ray curable resin layer peelably laminated on a substrate, wherein the active energy ray curable resin layer has an infrared spectral spectrum of 810 cm⁻¹. －１ Absorbance of the IR peak (T810) and 830 cm －１ A transfer film in which the IR peak absorbance ratio (T810 / T830) of the IR peak absorbance (T830) is 0.60 to 1.

20.

2. The transfer film according to claim 1, wherein the thickness of the active energy ray curable resin layer is 0.5 μm or more and 7.0 μm or less.

3. The transfer film according to claim 1 or 2, wherein the substrate has a release layer.

4. The transfer film according to claim 1 or 2, wherein the peel force between the substrate and the active energy ray curable resin layer is 0.12 N / 25 mm or less.

5. The transfer film according to claim 1 or 2, wherein the active energy ray curable resin layer is a curable resin layer made of a curable composition, and the curable composition contains a polyfunctional (meth)acrylic polymer and / or a urethane (meth)acrylate oligomer.

6. The transfer film according to claim 5, wherein the curable composition is a curable composition of the following embodiments I or II: <Embodiment I> A curable composition containing 60% by mass or more of a polyfunctional (meth)acrylic polymer based on 100% by mass of the total solid content of the curable composition; <Embodiment II> A curable composition containing 60% by mass or more of a urethane (meth)acrylate oligomer (A) having four or more functional groups based on 100% by mass of the total solid content of the curable composition.

7. The transfer film according to claim 6, wherein the curable composition of embodiment I further contains a urethane (meth)acrylate oligomer (B) having 1 to 3 functional groups.

8. The transfer film according to claim 6, wherein the curable composition of embodiment II further contains a urethane (meth)acrylate oligomer (B) having 1 to 3 functional groups.

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