Release sheet

Abstract

The present invention provides a release sheet using a printed base material, wherein the release sheet has improved peelability of an adhesive layer. Provided is a release sheet having a printing ink layer on a base material, and having a release layer (A) on the printing ink layer, wherein the printing ink layer has a printing part and a non-printing part, and the release layer (A) contains a compound having an alkyl group having 8 or more carbon atoms.

Description

Peel-off sheet

[0001] The present invention relates to a release sheet.

[0002] Release sheets are used, for example, to protect the surface of adhesive products. Adhesive products are generally supplied with a release sheet attached, and the release sheet is peeled off from the adhesive product and discarded when the adhesive product is used.

[0003] On the other hand, adhesive products may be printed with, for example, pictures, letters, numbers, patterns, pictures, symbols, figures, etc. in order to display the manufacturer's name, trademark, etc., or to impart design features. For example, wallpaper has been proposed that has a picture-printed layer and a release layer in this order on one side of a substrate, and an adhesive layer on the other side of the substrate (see, for example, Patent Document 1).

[0004] Japanese Patent Application Publication No. 7-216759

[0005] However, if a printed ink layer is present between the substrate and the release layer, the peelability (peeling force) between the release layer and the adhesive layer may become unstable. For example, the peeling force of the printed portion of the printed ink layer tends to be greater than that of the non-printed portion.

[0006] It was discovered that the thickness of the release layer is involved in the above problem. That is, the thickness of the release layer on the printed area tends to be thinner than the thickness of the release layer on the non-printed area, and generally, a thinner release layer tends to increase the peel force.

[0007] Therefore, an object of the present invention is to provide a release sheet using a printed substrate, which has improved releasability of the adhesive layer.

[0008] As a result of extensive research, the inventors discovered that a release layer containing a compound having an alkyl group with 8 or more carbon atoms is less susceptible to the influence of printed and non-printed areas, which led to the creation of the present invention.

[0009] That is, the above-mentioned objects of the present invention have been achieved by the following inventions. [1] A release sheet having a printed ink layer on a substrate and a release layer (A) on the printed ink layer, wherein the printed ink layer has printed areas and non-printed areas, and the release layer (A) contains a compound having an alkyl group having 8 or more carbon atoms. [2] The release sheet according to [1], wherein the release layer (A) is a cured layer of an active energy ray-curable composition containing a compound having an alkyl group having 8 or more carbon atoms, or a cured layer of a thermosetting composition containing a compound having an alkyl group having 8 or more carbon atoms. [3] The release sheet according to [2], wherein the release layer (A) is a cured layer of an active energy ray-curable composition. [4] The release sheet according to [3], wherein the active energy ray-curable composition contains a polymerizable long-chain alkyl compound (a), which is a compound having an ethylenically unsaturated group and an alkyl group having 8 or more carbon atoms in the molecule. [5] The release sheet according to [3] or [4], wherein the active energy ray-curable composition further contains a polymerizable compound (c) having an ethylenically unsaturated group in the molecule and not having an alkyl group having 8 or more carbon atoms. [6] The release sheet according to any one of [1] to [5], wherein a resin layer is provided between the printing ink layer and the release layer (A). [7] The release sheet according to [6], wherein the surface free energy of the resin layer is greater than the surface free energy of the release layer (A). [8] The release sheet according to [6], wherein the surface free energy of the resin layer is 30 mN / m or more and 70 mN / m or less. [9] The release sheet according to any one of [1] to [8], wherein the surface free energy of the release layer (A) is 17 mN / m or more and less than 43 mN / m.

[10] The release sheet according to any one of [1] to [9], wherein the peel strength between the release layer (A) and an adhesive tape is 0.2 N / 50 mm or more and less than 8 N / 50 mm.

[11] The release sheet according to any one of [1] to

[10] , wherein the product of Young's modulus (MPa) and thickness (μm) of the release sheet is 30,000 MPa μm or more and less than 300,000 MPa μm.

[12] The release sheet according to any one of [1] to

[11] , wherein the substrate is made of a plastic film.

[13] The release sheet according to any one of [1] to

[12] , wherein the substrate is made of a white plastic film.

[14] The release sheet according to

[12] or

[13] , wherein the plastic film is a polyester film.

[15] The release sheet according to any one of [1] to

[14] , wherein the base material has a release layer (B) on the side opposite to the release layer (A).

[0010] According to the present invention, it is possible to provide a release sheet using a printed substrate, which has improved releasability from an adhesive layer.

[0011] Fig. 1 is a schematic cross-sectional view showing an example of a release sheet according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a release sheet according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view of an example of an adhesive member with a release sheet. Fig. 4 is a schematic cross-sectional view of an example of an adhesive member with a release sheet. Fig. 5 is a schematic cross-sectional view of an example of a double-sided adhesive sheet with a release sheet. Fig. 6 is a schematic cross-sectional view of an example of a double-sided adhesive sheet with a release sheet.

[0012] The release sheet of the present invention has a printed ink layer having a printed area and a non-printed area on a substrate, and a release layer (A) on the printed ink layer, which contains a compound having an alkyl group having 8 or more carbon atoms.

[0013] 1 is a schematic cross-sectional view showing an example of a release sheet of the present invention. The release sheet 1 has a printed ink layer 12 and a release layer (A) 13 on a substrate 11. The printed ink layer 12 is composed of a printed area 12a and a non-printed area 12b.

[0014] A release layer (A) containing a compound having an alkyl group with 8 or more carbon atoms has the advantage that the releasability from the adhesive layer is relatively small in dependence on the thickness of the release layer. In other words, a release layer (A) containing a compound having an alkyl group with 8 or more carbon atoms has the advantage of being less affected by the thickness difference between the printed and non-printed areas on the printed surface of the substrate. To explain this in detail, in FIG. 1, the thickness of the release layer (A) 13 on the printed area 12a tends to be small, and the thickness of the release layer (A) 13 on the non-printed area 12b tends to be large. In conventional release layers, changes in the thickness of the release layer were a factor that made the releasability from the adhesive layer unstable. Against this technical background, the release layer (A) has relatively small thickness dependence, so by applying it to the printed surface of a printed substrate, the releasability from the adhesive layer is improved.

[0015] In the following description, the terms "peeling property" and "peeling force" refer to the properties of a release layer relative to an adhesive layer (adhesive tape).

[0016] [Release Layer (A)] The release layer (A) constituting the release sheet of the present invention contains a compound having an alkyl group having 8 or more carbon atoms. The compound having an alkyl group having 8 or more carbon atoms is preferably a compound having a linear or branched alkyl group having 8 or more carbon atoms. Hereinafter, an alkyl group having 8 or more carbon atoms may be referred to as a "long-chain alkyl group," and a compound having an alkyl group having 8 or more carbon atoms may be referred to as a "long-chain alkyl compound."

[0017] The carbon number of the long-chain alkyl group in the long-chain alkyl compound is preferably 10 or more, more preferably 12 or more, and preferably 30 or less, more preferably 28 or less, and particularly preferably 25 or less.

[0018] The release layer (A) is preferably a cured layer of an active energy ray-curable composition or a cured layer of a thermosetting composition. Among these, a cured layer of an active energy ray-curable composition is suitable for laminating on a printed ink layer because it can be formed at a relatively low temperature. That is, by laminating a cured layer of an active energy ray-curable composition on a printed ink layer, changes in appearance due to discoloration or shrinkage of the printed ink layer, and detachment of the printed ink layer due to reduced adhesion between the printed ink layer and the substrate are suppressed. Furthermore, a cured layer of an active energy ray-curable composition is advantageous in terms of releasability.

[0019] Hereinafter, an embodiment in which the release layer (A) is a cured layer of an active energy ray-curable composition containing a long-chain alkyl compound will be described in detail.

[0020] The active energy ray-curable composition contains a compound that polymerizes and cures when exposed to active energy rays (hereinafter, sometimes referred to as a polymerizable compound). Examples of such polymerizable compounds include compounds (monomers and oligomers) having at least one ethylenically unsaturated group in the molecule. Preferred examples of the ethylenically unsaturated group include an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, an allyl group, and a vinyl group.

[0021] The long-chain alkyl compound contained in the active energy ray-curable composition is preferably a polymerizable compound. That is, the long-chain alkyl compound contained in the active energy ray-curable composition is preferably a compound containing an ethylenically unsaturated group and a long-chain alkyl group in the molecule (hereinafter, sometimes referred to as "polymerizable long-chain alkyl compound (a)"). When the long-chain alkyl compound is the polymerizable long-chain alkyl compound (a), an increase in the peel strength of the release layer on the printed area is further suppressed.

[0022] The long-chain alkyl compound contained in the active energy ray-curable composition may not be polymerizable. Hereinafter, a long-chain alkyl compound that is not polymerizable may be referred to as a "non-polymerizable long-chain alkyl compound (b)." Preferred examples of such non-polymerizable long-chain alkyl compounds (b) include long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing acrylic resins, long-chain alkyl group-containing polyester resins, long-chain alkyl group-containing alkyd resins, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing amine compounds.

[0023] When the active energy ray-curable composition contains only a non-polymerizable long-chain alkyl compound (b) as the long-chain alkyl compound, it preferably contains a compound having an ethylenically unsaturated group in the molecule and not having an alkyl group having 8 or more carbon atoms (hereinafter sometimes referred to as a "polymerizable compound (c)"). The polymerizable compound (c) will be described in detail below.

[0024] The active energy ray-curable composition preferably uses a combination of a polymerizable long-chain alkyl compound (a) and a non-polymerizable long-chain alkyl compound (b), or a combination of a polymerizable long-chain alkyl compound (a) and a polymerizable compound (c), and particularly preferably uses a combination of a polymerizable long-chain alkyl compound (a) and a polymerizable compound (c). That is, it is particularly preferable for the active energy ray-curable composition to contain a compound having an ethylenically unsaturated group and an alkyl group having 8 or more carbon atoms in the molecule (polymerizable long-chain alkyl compound (a)), and a compound having an ethylenically unsaturated group in the molecule but not having an alkyl group having 8 or more carbon atoms (polymerizable compound (c)).

[0025] In the following description, "(meth)acrylate" is a general term for "acrylate" and "methacrylate."

[0026] The polymerizable long-chain alkyl compound (a) is preferably a compound containing an ethylenically unsaturated group and a long-chain alkyl group in the molecule. The carbon number of the long-chain alkyl group is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more. The carbon number of the long-chain alkyl group is preferably 30 or less, more preferably 28 or less, and particularly preferably 25 or less.

[0027] Examples of the polymerizable long-chain alkyl compound (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.

[0028] In particular, the following polymerizable long-chain alkyl compound (a) is preferably used. Examples of such compounds include a compound obtained by reacting a (meth)acrylate compound (d) having one or more (meth)acryloyl groups and one or more hydroxyl groups in the molecule, a polyisocyanate compound (e) having two or more isocyanate groups in the molecule, and a higher alcohol (f) having 8 to 30 carbon atoms.

[0029] Examples of the (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 compounds. Examples of the alkyleneoxy group 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 alkyleneoxy groups (e.g., ethyleneoxy groups, propyleneoxy groups, butyleneoxy groups, etc.) in the molecule.

[0030] Among the above compounds, from the viewpoint of making the peeling force relatively small and improving the heat resistance, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and (meth)acrylates having 2 to 30 alkyleneoxy groups in the molecule are preferably used.

[0031] Examples of the polyisocyanate compound (e) include known compounds such as diisocyanate compounds such as hexamethylene diisocyanate, lysine diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, tolidine diisocyanate, tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate, as well as biuret polyisocyanate compounds obtained by reacting these various diisocyanate compounds with water, adduct polyisocyanate compounds obtained by reacting various diisocyanate compounds with polyhydric alcohols such as trimethylolpropane, and polymers obtained by isocyanurating various compounds.

[0032] Among the above polyisocyanate compounds, compounds having a molecular weight of 50 to 500 are preferred, compounds having a molecular weight of 100 to 400 are more preferred, and compounds having a molecular weight of 130 to 300 are particularly preferred. For example, hexamethylene diisocyanate (molecular weight 168) and diphenylmethane diisocyanate (molecular weight 250) are exemplified as preferred compounds. Furthermore, polyisocyanate compounds having an aromatic group such as a phenyl group (phenylene group) or a naphthyl group (naphthalene group) in the molecule are preferred.

[0033] Examples of the 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.

[0034] Commercially available products can be used as the higher alcohol (f). For example, examples of linear saturated higher alcohols include "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, and Conol 2280 (Shin-Nihon (trade name of Honrika Co., Ltd.), "Kalcol (registered trademark)" 0898, Kalcol 0880, Kalcol 1098, Kalcol 2098, Kalcol 4098, Kalcol 6098, Kalcol 8098, Kalcol 200GD, Kalcol 2475, Kalcol 2474, Kalcol 2473, Kalcol 2463, Kalcol 2455, Kalcol 2450, Kalcol 4250, Kalcol 6870 , Kalcol 6850, Kalcol 8688, Kalcol 8665, Kalcol 220-80 (trade names of Kao Corporation), and linear unsaturated higher alcohols such as "Rikacol (registered trademark)" 60B, Rikacol 70B, Rikacol 75BJ, Rikacol 85BJ, Rikacol 90B, Rikacol 90BR, Rikacol 90BHR, Rikacol 110BJ, "Angecol (registered trademark)" 50A, Examples of branched higher alcohols include Njecol 60AN, Njecol 70AN, Njecol 80AN, Njecol 85AN, Njecol 90AN, Njecol 90NR, and Njecol 90NHR (trade names of New Japan Chemical Co., Ltd.), and Njecol (registered trademark) 160BR, Njecol 200A, and Njecol 240A (trade names of New Japan Chemical Co., Ltd.) are given as examples.

[0035] Examples of the polymerizable compound (c) that can be contained in the active energy ray-curable composition include methyl (meth)acrylate, ethyl diethylene glycol (meth)acrylate, ethoxy diethylene glycol (meth)acrylate, methoxy triethylene 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 propoxy tri(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 acrylate, 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, pentaerythritol tri(meth)acrylate-isophorone diisocyanate urethane oligomer, and the like.

[0036] Among the above polymerizable compounds (c), compounds having 2 to 10 ethylenically unsaturated groups in the molecule are preferred, compounds having 2 to 7 ethylenically unsaturated groups in the molecule are more preferred, and compounds having 3 to 6 ethylenically unsaturated groups in the molecule are particularly preferred. By incorporating such a polymerizable compound (c), the hardness of the release layer is likely to be improved, and the solvent resistance and heat resistance are likely to be improved.

[0037] Among the polymerizable compounds (c), compounds having a theoretical number average molecular weight of 400 or more but less than 1,000 and 5 to 7 ethylenically unsaturated groups are particularly preferred. Representative examples of such compounds include, but are not limited to, dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate. Here, the theoretical number average molecular weight is calculated from the molecular formula structure. For commercially available products, the theoretical number average molecular weight is the number average molecular weight listed in a catalog or the like, or is calculated from the listed molecular formula structure.

[0038] 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 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 7% by mass or more, relative to 100% by mass of the total solids content of the active energy ray-curable composition, from the viewpoint of reducing the peel strength of the release layer. On the other hand, if the content of the long-chain alkyl compound is too high, the strength (hardness) of the release layer may decrease, and the solvent resistance and heat resistance may also decrease. Therefore, the content of the long-chain alkyl compound is preferably 70% by mass or less, more preferably 50% by mass or less, and particularly preferably 30% by mass or less.

[0039] From the viewpoint of increasing the strength (hardness) of the release layer and improving the solvent resistance and heat resistance (suppressing an increase in peel strength after heating), the content of the polymerizable compound (c) in the active energy ray-curable composition is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more, relative to 100% by mass of the total solid content of the active energy ray-curable composition. On the other hand, if the content of the polymerizable compound (c) is too high, the peel strength of the surface of the release layer may increase, so the content of the polymerizable compound (c) is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0040] 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's ketone, benzil, 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-hydroxycyclohexyl phenyl ketone; and sulfur compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone. These photopolymerization initiators may be used alone or in combination of two or more.

[0041] Furthermore, photopolymerization initiators are generally commercially available and can be used. For example, "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, and DAROCUR 1173, all manufactured by Ciba Specialty Chemicals Co., Ltd.; "Speedcure (registered trademark)" MBB, Speedcure PBZ, Speedcure ITX, Speedcure CTX, Speedcure EDB, "Esacure (registered trademark)" ONE, and Esacure KIP150, Esacure KTO46, etc., and "KAYACURE (registered trademark)" DETX-S, KAYACURE CTX, KAYACURE BMS, KAYACURE DMBI, etc., manufactured by Nippon Kayaku Co., Ltd.

[0042] The content of the photopolymerization initiator is suitably in the range of 0.1 to 10% by mass, preferably 0.5 to 8% by mass, relative to 100% by mass of the total solid content of the active energy ray-curable composition.

[0043] Examples of active energy rays for curing the active energy ray-curable composition include ultraviolet rays, visible light, infrared rays, electron beams, α rays, β rays, γ rays, etc. Among these active energy rays, ultraviolet rays and electron beams are preferred, and ultraviolet rays are particularly preferred.

[0044] The light source for irradiating ultraviolet light is not particularly limited, and examples thereof include 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, and xenon lamps. ArF excimer lasers, KrF excimer lasers, excimer lamps, and synchrotron radiation can also be used. Among these, ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arc lamps, xenon arc lamps, and metal halide lamps are preferably used. Furthermore, when irradiating ultraviolet light, it is preferable to irradiate in an atmosphere with a low oxygen concentration, for example, an atmosphere with an oxygen concentration of 500 ppm or less, since this allows for efficient curing.

[0045] The ultraviolet light intensity was 50 mJ / cm ２ More than 100 mJ / cm is preferable. ２ More preferably, 150 mJ / cm or more is particularly preferable. ２ The irradiation dose of ultraviolet light is preferably 2000 mJ / cm or more. ２ Preferably, 1000 mJ / cm or less ２ The following is more preferred:

[0046] Next, an embodiment in which the release layer is a cured layer of a thermosetting composition containing a long-chain alkyl compound will be described in detail.

[0047] Examples of long-chain alkyl compounds contained in the thermosetting composition include long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing acrylic resins, long-chain alkyl group-containing polyester resins, long-chain alkyl group-containing ether compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing alkyd resins, etc. These long-chain alkyl compounds may be the same as the non-polymerizable long-chain alkyl compound (b) described above.

[0048] The long-chain alkyl group-containing polyvinyl resin can be preferably synthesized by reacting a polyvinyl alcohol polymer (including a partially saponified product of polyvinyl acetate), an ethylene-vinyl alcohol polymer (including a partially saponified product of ethylene-vinyl acetate copolymer), or a vinyl alcohol-acrylic acid copolymer (including a partially saponified product of vinyl acetate-acrylic acid copolymer) with a long-chain alkyl group-containing isocyanate compound. In this case, hydroxyl groups can be incorporated into the polymer by adjusting the amount of the long-chain alkyl group-containing isocyanate compound added.

[0049] Preferred examples of the long-chain alkyl group-containing isocyanate compound include monoisocyanate compounds having an alkyl group with 8 or more carbon atoms, and specific examples include octyl isocyanate, nonyl isocyanate, decyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, and octadecyl isocyanate.

[0050] Examples of the long-chain alkyl group-containing acrylic resin include homopolymers or copolymers of acrylic or methacrylic monomers having a long-chain alkyl group, such as octyl acrylate, octyl methacrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, and octadecyl methacrylate.

[0051] Examples of other monomers that can be used in the copolymer include acrylic acid, methacrylic acid, acrylamide, methacrylamide, and styrene.

[0052] The long-chain alkyl group-containing alkyd resin is preferably a condensate of a polybasic acid having a long-chain alkyl group and a polyhydric alcohol modified with a fatty oil or a fatty acid. Preferred polybasic acids include saturated polybasic acids such as phthalic anhydride, terephthalic acid, succinic acid, adipic acid, and sebacic acid; unsaturated polybasic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic anhydride; and other polybasic acids such as cyclopentadiene-maleic anhydride adduct, terpene-maleic anhydride adduct, and rosin-maleic anhydride adduct. Preferred polyhydric alcohols include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, and tetramethylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; and tetrahydric or higher alcohols such as diglycerin, triglycerin, pentaerythritol, dipentaerythritol, mannitol, and sorbitol. Preferred examples of the modifier include soybean oil, linseed oil, tung oil, castor oil, dehydrated castor oil, coconut oil, and their fatty acids, as well as oils and fatty acids such as stearic acid, oleic acid, linoleic acid, linoleic acid, eleostearic acid, ricinoleic acid, and dehydrated ricinoleic acid, natural resins such as rosin, kovar, amber, and shellac, and synthetic resins such as ester gum, phenolic resin, urea resin, and melamine resin. Furthermore, cured resins of stearic acid-modified alkyd resins and / or stearic acid-modified acrylic resins with amino resins are also preferred from the viewpoint of a balance between application and release properties.

[0053] The long-chain alkyl compounds described above are commercially available and can be used. Preferred examples of commercially available products include the Resem series "K-256," "N-137," "P-677," and "Q-472" manufactured by Chukyo Yushi Co., Ltd., the Ashiosin series "RA-80," "RA-95H," and "RA-585S" manufactured by Asio Sangyo Co., Ltd., the ZF-15 and ZF-15H manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., the Epomin "RP-20" manufactured by Nippon Shokubai Co., Ltd., the Tesfine 303 manufactured by Resonac Co., Ltd., and the Piroil series "1010," "1050," "1070," "HT," and "406" manufactured by Lion Specialty Chemicals Co., Ltd.

[0054] The thermosetting composition preferably contains a crosslinking agent. Examples of the crosslinking agent include epoxy-based crosslinking agents, isocyanate-based crosslinking agents, oxazoline-based crosslinking agents, carbodiimide-based crosslinking agents, and melamine-based crosslinking agents. Among these, melamine-based crosslinking agents are particularly preferred.

[0055] Examples of epoxy crosslinking agents include ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, and polybutadiene diglycidyl ether.

[0056] Examples of the isocyanate crosslinking agent include hexamethylene diisocyanate, isophorone diisocyanate tolylene diisocyanate, and methylene diphenyl diisocyanate.

[0057] Examples of the oxazoline crosslinking agent include compounds having an oxazoline group, such as 2,2'-bis(2-oxazoline), 2,2'-ethylene-bis(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis(2-oxazoline), and bis(2-oxazolinylcyclohexane) sulfide, and oxazoline group-containing polymers.

[0058] Preferred examples of the carbodiimide crosslinking agent include compounds having a carbodiimide group, such as p-phenylene-bis(2,6-xylylcarbodiimide), tetramethylene-bis(t-butylcarbodiimide), and cyclohexane-1,4-bis(methylene-t-butylcarbodiimide), and polycarbodiimide, which is a polymer having a carbodiimide group.

[0059] The melamine compound used as a melamine-based crosslinking agent is a general term for compounds in which the amino groups of so-called melamine [1,3,5-triazine-2,4,6-triamine], in which an amino group is bonded to each of the three carbon atoms of a triazine ring, have been modified in various ways, including compounds in which multiple triazine rings are condensed. The type of modification is preferably a methylolated melamine compound in which at least one of the hydrogen atoms of the three amino groups has been methylolated, and more preferably an alkyl-etherified melamine compound in which the methylol groups of a methylolated melamine compound have been partially or completely etherified with a lower alcohol having 1 to 4 carbon atoms.

[0060] Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol.

[0061] Commercially available melamine crosslinking agents can be used. Examples of commercially available products include "Super Beckamine (registered trademark)" J-820-60, J-821-60, J-1090-65, J-110-60, J-117-60, J-127-60, J-166-60B, J-105-60, G840, and G821 manufactured by DIC Corporation, and "U-Ban (registered trademark)" 20SB, 20SE60, 21R, 22R, 122, 125, 128, 220, 225, 228, 28-60, 2020, 60R, 62, 62E, 360, 165, 166-60, and 169 manufactured by Mitsui Chemicals, Inc. , 2061, Sumitomo Chemical Co., Ltd. "Sumimar (registered trademark)" M-100, M-40S, M-55, M-66B, Japan Cytec Industries Co., Ltd. "Cymel (registered trademark)" 303, 325, 327, 350, 370, 235, 202, 238, 254, 272, 1130, Sanwa Chemical Co., Ltd. "Nikalac (registered trademark)" MS17, MX15, MX430, MX600, Harima Chemical Co., Ltd. Bansemin SM-975, SM-960, Hitachi Chemical Co., Ltd. "Melan (registered trademark)" 265, 2650L, and the like.

[0062] The thermosetting composition preferably contains an acid catalyst to accelerate curing. Examples of the acid catalyst include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and p-toluenesulfonic acid. Among these, p-toluenesulfonic acid is preferably used.

[0063] From the viewpoint of improving releasability after hot pressing, the content of the long-chain alkyl group-containing compound in the thermosetting composition is preferably 3% by mass or more, more preferably 5% by mass or more, and particularly preferably 7% by mass or more, relative to 100% by mass of the total solid content of the thermosetting composition. On the other hand, if the content of the long-chain alkyl group-containing compound is too high, 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 group-containing compound is preferably 95% by mass or less, more preferably 90% by mass or less, and particularly preferably 85% by mass or less.

[0064] From the viewpoint of improving the solvent resistance of the release layer (A), the content of the crosslinking agent in the thermosetting composition is preferably 3% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more, relative to 100% by mass of the total solid content of the thermosetting composition. On the other hand, if the content of the crosslinking agent is too high, the peeling force of the release layer may become high or unstable, so the content of the crosslinking agent is preferably 97% by mass or less, more preferably 95% by mass or less.

[0065] From the viewpoint of further improving the solvent resistance of the release layer (A), the content of the crosslinking agent is preferably 1.0 times by mass or more, more preferably 2.0 times by mass or more, even more preferably 2.5 times by mass or more, particularly preferably 3.0 times by mass or more, and most preferably 5.0 times by mass or more, the upper limit of which is about 20.0 times by mass, of the long-chain alkyl group-containing compound.

[0066] From the viewpoint of improving releasability and solvent resistance, the content of the acid catalyst in the thermosetting composition is preferably in the range of 0.1 to 10 mass%, more preferably in the range of 0.3 to 5 mass%, and particularly preferably in the range of 0.5 to 3 mass%, relative to 100 mass% of the total solid content of the thermosetting composition.

[0067] The release layer (A) consisting of a cured layer of a thermosetting composition is formed by heat-curing the thermosetting composition applied to the substrate. The conditions for heat-curing (heating temperature, time) are not particularly limited, but the heating temperature is preferably 70°C or higher, more preferably 100°C or higher, and particularly preferably 150°C or higher. The upper limit is about 300°C. The heating time is preferably 3 to 300 seconds, more preferably 5 to 200 seconds.

[0068] The release layer (A) is formed by applying the above-mentioned active energy ray-curable composition or thermosetting composition to a printed substrate, drying it, and curing it. Preferred coating methods include reverse coating, spray coating, bar coating, gravure coating, rod coating, die coating, spin coating, extrusion coating, and curtain coating.

[0069] The release layer (A) has the advantage that the releasability from the adhesive layer is relatively small depending on the thickness of the release layer, and moreover, the thickness dependency is relatively small in the region where the thickness of the release layer is relatively small. Furthermore, if the thickness of the release layer is relatively thin, it can be expected that the display quality (appearance such as clarity) of the printing ink layer when viewed from the release layer side will be maintained.

[0070] In order to ensure smooth peeling of the adhesive tape attached to the release layer, the peel force between the release layer and the adhesive tape is preferably less than 8 N / 50 mm, more preferably less than 5 N / 50 mm, even more preferably less than 3 N / 50 mm, and particularly preferably less than 2 N / 50 mm. The lower limit is preferably 0.2 N / 50 mm or more. The adhesive tape used is an acrylic adhesive tape or a silicone adhesive tape. Details of the method for measuring the peel force will be described later.

[0071] Even if the release layer (A) is relatively thin, it can achieve a low peel force (less than 8 N / 50 mm). From the viewpoint of maintaining the display quality (appearance such as clarity) of the printed ink layer when viewed from the release layer (A) side, the thickness of the release layer (A) is preferably 2,000 nm or less, more preferably 1,000 nm or less, even more preferably 800 nm or less, and particularly preferably 500 nm or less. On the other hand, from the viewpoint of reducing the thickness dependency of the release force, the thickness of the release layer (A) is preferably 50 nm or more, more preferably 80 nm or more, even more preferably 100 nm or more, and particularly preferably 150 nm or more. Here, the thickness of the release layer (A) means the thickness from the substrate. When a resin layer (described later) is present between the substrate and the release layer (A), the thickness of the release layer (A) means the thickness from the resin layer.

[0072] The peeling force of the release layer is correlated with the surface free energy of the release layer, and the smaller the surface free energy, the smaller the peeling force. In other words, it is preferable that the surface free energy of the release layer (A) is relatively small.

[0073] Specifically, the surface free energy of the release layer (A) is preferably less than 43 mN / m, more preferably less than 35 mN / m, even more preferably less than 30 mN / m, and particularly preferably less than 27 mN / m.The surface free energy of the release layer (A) is preferably 15 mN / m or more, preferably 17 mN / m or more, and particularly preferably 19 mN / m or more.Here, the surface roughness free energy E can be measured using a contact angle meter, for example, Kyowa Interface Science Co., Ltd.'s "Drop Master DM501".Details will be described later.

[0074] It is preferable that the release layer (A) does not substantially contain silicone compounds or fluorine compounds, which have been conventionally known as release agents. Here, "substantially not containing" means that the content of each of the silicone compounds and fluorine compounds is 3% by mass or less, relative to 100% by mass of the total solid content of the release layer (A). The above-mentioned contents are each preferably 2% by mass or less, more preferably 1% by mass or less, and most preferably 0% by mass.

[0075] When a silicone compound is contained in the release layer (A), it may be difficult to adjust the release force. In addition, it is preferable not to use a fluorine-based compound, since in recent years, there has been a growing movement to abolish or restrict the use of an organic fluorine compound "PFAS" due to its accumulation in nature and its toxicity to humans.

[0076] [Substrate] The substrate constituting the release sheet of the present invention is not particularly limited, and known substrates can be used. Examples include plastic films, paper, resin-laminated paper, and resin-impregnated paper. Among these, from the viewpoint of preventing the penetration of printing ink or a coating liquid for a release layer into the substrate, plastic films and resin-laminated paper are preferred, and plastic films are particularly preferred.

[0077] Examples of 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 diacetyl cellulose film and triacetyl cellulose film, polysulfone film, polyether ether ketone film, polyether sulfone 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 more preferred.

[0078] An example of resin-laminated paper is paper such as kraft paper laminated with polyethylene resin.

[0079] The thickness of the substrate is preferably 20 μm or more, more preferably 25 μm or more, and particularly preferably 38 μm or more, from the viewpoint of processability in the printing process and the release layer lamination process, and from the viewpoint of the handleability of the adhesive member with a release sheet described later. On the other hand, if the thickness of the substrate is large, the rigidity increases, and the peel angle when peeling the release sheet becomes small, which may result in a poor peeling feel. For this reason, the thickness of the substrate is preferably 188 μm or less, more preferably 100 μm or less, and particularly preferably 75 μm or less.

[0080] The release sheet of the present invention is preferably applied to a pressure-sensitive adhesive member. Examples of pressure-sensitive adhesive members include a pressure-sensitive adhesive layer, a single-sided pressure-sensitive adhesive sheet, and a double-sided pressure-sensitive adhesive sheet. In such pressure-sensitive adhesive members to which the release sheet is applied, from the viewpoint of obtaining a good release feel when the release sheet is peeled off from the pressure-sensitive adhesive member, the product of the Young's modulus (MPa) and the thickness (μm) of the release sheet of the present invention is preferably 30,000 MPa μm or more and less than 300,000 MPa μm, and more preferably 50,000 MPa μm or more and less than 120,000 MPa μm. Methods for measuring the Young's modulus and thickness will be described later.

[0081] The above technical features can be preferably realized by selecting the type and thickness of the substrate, for example, by using a polyethylene terephthalate film having a thickness in the range of 20 to 188 μm as the substrate.

[0082] From the viewpoint of improving adhesion to the printed ink layer, the surface roughness Ra of the substrate on which the printed ink layer is to be formed is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 15 nm or more, while from the viewpoint of the display quality of the printed ink layer, it is preferably 500 nm or less, more preferably 400 nm or less, and particularly preferably 300 nm or less.

[0083] From the viewpoint of improving the appearance of the print, the substrate is preferably a white substrate. As the white substrate, a white plastic film is preferable, and among them, a white polyester film is preferable, and a white polyethylene terephthalate film is particularly preferable.

[0084] As the white polyester film, for example, a polyester film in which a white pigment such as titanium oxide or calcium carbonate is kneaded is preferable.

[0085] The whiteness of the white substrate (white polyester film) is preferably 75 or more, more preferably 80 or more, and particularly preferably 85 or more. The whiteness is preferably 110 or less, more preferably 105 or less, and particularly preferably 100 or less.

[0086] [Printed Ink Layer] The release sheet of the present invention has a printed ink layer having printed and non-printed areas on a substrate. The printed pattern having printed and non-printed areas preferably includes at least one selected from letters, numbers, patterns, pictures, symbols, and figures. Examples of such printed patterns include manufacturer names, trademarks, logos, symbol marks, front / back identification marks, and design marks.

[0087] The printing rate of the printed pattern in the printing ink layer is preferably in the range of 3 to 80%, more preferably in the range of 5 to 70%, and particularly preferably in the range of 7 to 60%. The release sheet of the present invention is preferably effective at such a printing rate. Here, the printing rate is the ratio of the total area of ​​the printed portion to the total area of ​​the printing ink layer covered with the release layer (A).

[0088] The printed ink layer can be formed by printing directly on the substrate. Alternatively, the substrate may be subjected to a corona treatment or plasma treatment in advance, or an easy-adhesion layer may be provided thereon. In the present invention, it is preferred to form the printed ink layer by printing directly on the substrate.

[0089] Printing can be performed using conventional printing methods such as gravure, gravure offset, silkscreen printing, and flexography. The ink used for printing preferably contains, for example, a pigment and a binder resin. Specifically, general gravure ink or flexography ink can be used. When the ink is an oil-based gravure ink, the binder resin can be a mixture of a urethane resin and a vinyl chloride-vinyl acetate copolymer resin. The ink may contain various additives other than the pigment and binder resin, as well as a solvent (e.g., a volatile organic solvent). Examples of inks that can be used include vegetable oil ink and biomass ink. Among these inks, low-halogen urethane ink is preferred because it tends to reduce the increase in peel strength of the release layer on the printed area.

[0090] [Resin Layer] It is preferable to provide a resin layer between the printed ink layer and the release layer (A). Figure 2 is a schematic cross-sectional view showing an example of an embodiment in which a resin layer is provided between the printed ink layer and the release layer (A). The release sheet 1 has a printed ink layer 12 on a substrate 11, a resin layer 14 laminated on the printed ink layer 12, and a release layer (A) 13 laminated on the resin layer 14.

[0091] The resin layer serves to preferably reduce the difference in thickness between the printed and non-printed areas of the printing ink layer. That is, by providing the resin layer, the difference in thickness between the release layer (A) on the printed area and the release layer (A) on the non-printed area may be reduced, and the peel force of the release layer (A) may be further stabilized.

[0092] Furthermore, by providing a resin layer between the printing ink layer and the release layer (A), direct contact between the printing ink layer and the release layer (A) is preferably suppressed, which may suppress the migration of ink components from the printing ink layer to the release layer (A) and reduce the effect on the peel strength of the release layer (A).

[0093] It is preferable that the resin layer does not affect the adhesion to the release layer (A), the coating property of the release layer (A), and the peelability of the release layer (A).For example, from the viewpoint of the adhesion to the release layer (A) and the coating property of the release layer (A), the surface free energy of the resin layer is preferably 30 mN / m or more, more preferably 35 mN / m or more, even more preferably 38 mN / m or more, and particularly preferably 40 mN / m or more.Furthermore, the surface free energy of the resin layer is preferably 70 mN / m or less, more preferably 60 mN / m or less, even more preferably 55 mN / m or less, and particularly preferably 50 mN / m or less.

[0094] When viewed from the perspective of the overall configuration of the release sheet, the surface free energy of the resin layer is preferably greater than the surface free energy of the release layer (A). Specifically, the difference (E0-E1) between the surface free energy (E0) of the resin layer and the surface free energy (E1) of the release layer (A) is preferably 5 mN / m or more, more preferably 10 mN / m or more, and particularly preferably 15 mN / m or more. The upper limit is preferably 30 mN / m or less. This allows for both good adhesion between the resin layer and the release layer (A) and good releasability of the release layer (A).

[0095] From the above viewpoints, the resin layer is preferably composed of a thermosetting resin or an active energy ray-curable resin. That is, the resin layer is preferably a thermosetting resin layer or an active energy ray-curable resin layer. From the viewpoints of the coatability and adhesion of the release layer (A) laminated on the resin layer, the resin layer is more preferably a thermosetting resin layer.

[0096] The thermosetting resin constituting the thermosetting resin layer may be a polymer and / or polymeric compound having a functional group capable of self-crosslinking or reacting with a crosslinking agent to form a covalent bond, and may be formed using any crosslinking accelerator and catalyst. Preferred examples of the polymer and polymeric compound include polyvinyl alkyl carbamate, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, ethyl cellulose, cellulose acetate, nitrocellulose, polyurea, polyurethane, urethane prepolymer, carboxy-modified polyurethane, amino-modified polyurethane, polyurethane acrylate, polyester acrylate, epoxy acrylate, unsaturated polyester, polyether acrylate, N-methylolacrylamide, melamine, methylolated melamine, alkyd resin, phenolic resin, furan resin, resorcinol resin, epoxy resin, or modified versions thereof. The crosslinking accelerator and catalyst may be selected appropriately depending on the combination of the crosslinking agent and the polymer and / or polymeric compound having a functional group capable of self-crosslinking or reacting with a crosslinking agent to form a covalent bond.

[0097] When the resin layer is a thermosetting resin layer, it is preferable that the thermosetting resin contains at least one selected from the group consisting of phenolic resin, alkyd resin, melamine resin, epoxy resin, urea resin, furan resin, resorcinol resin, unsaturated polyester resin, urethane resin, acrylic resin, acrylic urethane resin, and thermosetting polyimide. Furthermore, from the viewpoint of adhesion between the resin layer and the release layer (A), it is more preferable that the thermosetting resin contains at least one selected from the group consisting of alkyd resin, melamine resin, epoxy resin, unsaturated polyester resin, urethane resin, acrylic resin, and acrylic urethane resin, and it is particularly preferable that the thermosetting resin contains at least one selected from the group consisting of urethane resin, acrylic resin, and acrylic urethane resin.

[0098] When the resin layer is an active energy ray-curable resin layer, the active energy ray-curable resin is preferably formed from a photopolymerizable monomer (reactive diluent), a photopolymerizable oligomer, an unsaturated prepolymer or an unsaturated oligomer, and an optional photoinitiator.

[0099] Preferred examples of the photopolymerizable monomer include monofunctional monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acryloyl phosphate; bifunctional monomers such as 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, and hydroxypivalic acid ester neopentyl glycol diacrylate; and trifunctional or higher functional monomers such as dipentaerythritol, pentaerythritol triacrylate, and trimethylolpropane triacrylate.

[0100] Examples of the photopolymerizable oligomer include polyester acrylate, epoxy acrylate, polyurethane acrylate, polyether acrylate, polyether acrylate, silicon acrylate, alkyd acrylate, and melamine acrylate.

[0101] Preferred examples of the unsaturated prepolymer and oligomer include unsaturated polyester, polyester acrylate, epoxy acrylate, polyurethane acrylate, polyether acrylate, unsaturated acrylic resin, unsaturated silicone, and unsaturated fluororesin.

[0102] Preferred examples of the photoinitiator include benzophenone, methyl benzoylbenzoate, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-(4-(methylthio)phenyl-2-)morpholinopropane-1, benzoin isobutyl ether, benzoin propyl ether, benzoin ethyl ether, benzil, benzil dimethyl ketal, 2-chlorothioxanthone, and 2,4-diethylthioxanthone.

[0103] The resin layer can be laminated on the printing ink layer by coating, drying and curing in the same manner as the release layer (A) described above.

[0104] [Adhesive member with release sheet] The release sheet of the present invention is preferably applied to an adhesive member. An adhesive member to which a release sheet is attached may be hereinafter referred to as a "adhesive member with release sheet". Hereinafter, examples of the adhesive member include an adhesive layer, an adhesive tape, and a double-sided adhesive sheet.

[0105] When the pressure-sensitive adhesive member is a pressure-sensitive adhesive layer, the pressure-sensitive adhesive member with a release sheet preferably has a configuration (I) in which a pressure-sensitive adhesive layer is laminated on the surface of the release sheet of the present invention opposite to the release layer (A), and a configuration (II) in which a pressure-sensitive adhesive layer is laminated on the release layer (A) of the release sheet of the present invention. Among these, the configuration (I) is preferred.

[0106] When the release sheet of the present invention is applied to the above-mentioned form (I), the release sheet of the present invention preferably has a release layer (B) on the side of the substrate opposite to the release layer (A). A schematic cross-sectional view of one example of the above-mentioned form (I) is shown in Figure 3.

[0107] In Figure 3, a pressure-sensitive adhesive member 20 with a release sheet has a pressure-sensitive adhesive layer 21 laminated on the release sheet 1 of the present invention. The release sheet 1 of the present invention has a printed ink layer 12 and a release layer (A) 13 on one side of a substrate 11, and a release layer (B) on the other side of the substrate 11. The pressure-sensitive adhesive layer 21 is laminated on the release layer (B) 15 of the release sheet 1 of the present invention. Here, the release layer (B) is not particularly limited, and a known release agent can be used.

[0108] As shown in Fig. 2, the release sheet of the present invention applied to the above-mentioned form (I) preferably has a resin layer 14 between a printing ink layer 12 and a release layer (A) 13. A schematic cross-sectional view of an example of this PSA member with a release sheet is shown in Fig. 4.

[0109] In Figure 4, a release sheet-attached adhesive member 30 has an adhesive layer 31 laminated on the release sheet 1 of the present invention. The release sheet 1 of the present invention has a printed ink layer 12, a resin layer 14, and a release layer (A) 13, in this order, on one surface of a substrate 11, and has a release layer (B) 15 on the other surface of the substrate 11. The adhesive layer 31 is laminated on the release layer (B) 15 of the release sheet 1 of the present invention.

[0110]

[0003] A pressure-sensitive adhesive member with a release sheet is generally manufactured by a roll-to-roll method. Specifically, a supply roll of a release sheet is continuously unwound and transported while an adhesive layer is laminated and wound into a roll. The adhesive layer may be coated on the release sheet, or may be laminated by transferring an adhesive layer that has already been laminated on another release sheet.

[0111] For example, in the roll-shaped adhesive member 20 with a release sheet produced by the roll-to-roll method as described above, the adhesive layer 21 and the release layer (A) 13 are in surface contact with each other. This roll-shaped material is unwound and processed into a predetermined shape and size. At this time, it is preferable that the adhesive layer 21 and the release layer (A) 13 are smoothly peeled off from each other.

[0112] The release layer (A) in the present invention can be smoothly and stably peeled from the adhesive layer, but to further improve the peelability from the adhesive layer, it is preferable to provide the resin layer 14, as described above. In addition, to further improve the peelability between the release layer (A) and the adhesive layer, it is preferable that the peel strength of the release layer (B) is greater than that of the release layer (A).

[0113] Specifically, the peel strength of the release layer (B) is preferably at least 0.05 N / 50 mm, more preferably at least 0.1 N / 50 mm, greater than the peel strength of the release layer (A). The upper limit of the difference in peel strength is not particularly limited, but is preferably 10 N / 50 mm or less.

[0114] The adhesive member in the adhesive member with a release sheet may be a double-sided adhesive sheet. The double-sided adhesive sheet has an adhesive layer on each side of a support. Hereinafter, a double-sided adhesive sheet with a release sheet attached thereto may be referred to as a "double-sided adhesive sheet with a release sheet."

[0115] The release sheet of the present invention that is applied to the above-mentioned double-sided pressure-sensitive adhesive sheet with a release sheet preferably has a release layer (B) on the side of the substrate opposite to the release layer (A).

[0116] The double-sided pressure-sensitive adhesive sheet with a release sheet may, for example, be in a form in which the release sheet of the present invention is attached to at least one adhesive layer of a double-sided pressure-sensitive adhesive sheet having adhesive layers on both sides of a support, via the release layer (B) of the release sheet. The release sheet of the present invention may be applied to only one adhesive layer side of the double-sided pressure-sensitive adhesive sheet, or may be applied to both adhesive layers. It is preferred that the release sheet of the present invention be applied to both sides of the double-sided pressure-sensitive adhesive sheet.

[0117] 5 is a schematic cross-sectional view of an example of a double-sided pressure-sensitive adhesive sheet with a release sheet. In double-sided pressure-sensitive adhesive sheet 100 with a release sheet, release sheets 1 and 2 of the present invention are laminated on both sides of double-sided pressure-sensitive adhesive sheet 40. Double-sided pressure-sensitive adhesive sheet 40 has adhesive layers 42 and 43 provided on both sides of support 41. Release sheets 1 and 2 of the present invention each have a printed ink layer 12 and a release layer (A) 13 on one side of substrate 11, and a release layer (B) 15 on the other side of substrate 11.

[0118] Release sheet 1 and / or release sheet 2 preferably have a resin layer 14 between the printed ink layer 12 and the release layer (A) 13. A schematic cross-sectional view of an example of this type of double-sided PSA sheet with a release sheet is shown in Figure 6. Release sheets 1 and 2 each have a resin layer 14 between the printed ink layer 12 and the release layer (A) 13. The rest of the configuration is the same as in Figure 5.

[0119] When the release sheet of the present invention is applied to both sides of a double-sided PSA sheet, release sheets 1 and 2 of the present invention may be the same or different as long as the requirements of the present invention are met. For example, the ink composition or color or printed pattern of the printed ink layer may be different, or the composition or thickness of the release layer (A), the material or thickness of the substrate, etc. may be different.

[0120] A double-sided adhesive sheet with a release sheet can be produced, for example, by preparing an adhesive member 20 or 30 with a release sheet as shown in Figure 3 or Figure 4, and attaching the adhesive layer 21 or 31 of the adhesive member 20 or 30 with a release sheet to both sides of a support 41, respectively.

[0121] Examples of the support for the double-sided pressure-sensitive adhesive sheet include plastic film, paper, cloth, nonwoven fabric, and resin foam. The support is preferably a resin foam. By using a resin foam, peelability after application becomes relatively easy. Preferred examples of such resin foam include polyurethane foam, acrylic foam, polyester foam, and polyolefin foam (e.g., polyethylene foam, polypropylene foam, etc.). Among these, polyolefin foam is preferred, and polyethylene foam is more preferred.

[0122] The double-sided pressure-sensitive adhesive sheet is suitable for use, for example, in attaching hooks or notices, or in fixing electronic components or other members.

[0123] The adhesive for forming the adhesive layer is not particularly limited, and can be appropriately selected from known adhesives such as acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, styrene-diene block copolymer adhesives, vinyl alkyl ether adhesives, polyamide adhesives, fluorine-based adhesives, creep property-improved adhesives, and radiation-curable adhesives. Among these, silicone adhesives are preferred because they have good removability, such as no change in adhesive strength even when repositioned and no stickiness, excellent viscosity resistance, cold resistance, high weather resistance, and high chemical resistance. The adhesives may be used alone, or two or more types may be used in combination as needed.

[0124] The thickness of the adhesive layer is not particularly limited, and is generally, for example, from 5 μm to 100 μm, and preferably from 10 μm to 50 μm.

[0125] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0126] [Measurement and Evaluation Methods] (1) Measurement of Surface Free Energy of Release Layer and Resin Layer Using water, diiodomethane, and 1-bromonaphthalene as three liquids whose surface free energy and the values ​​of its components (dispersion force, polar force, and hydrogen bonding force) are known, the contact angle of each liquid on the release layer was measured at 23°C and 65% RH using a contact angle meter DropMaster DM501 (manufactured by Kyowa Interface Science Co., Ltd.). Five measurements were taken for one 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 Association, Vol. 15, No. 3, p. 96)), the values ​​for each component were calculated using the following formula, derived from the Kitazaki-Hata formula: (γSd γLd)1 / 2 + (γSp γLp)1 / 2 + (γSh γLh)1 / 2 = γL(1 + cos θ) / 2.

[0127] Here, γLd, γLp, and γLh respectively represent the dispersion force, polar force, and hydrogen bonding force components of the test liquid, θ represents the contact angle of the test liquid on the test surface, γSd, γSp, and γSh respectively represent the dispersion force, polar force, and hydrogen bonding force components of the layer surface, and γL represents the surface energy of each liquid. The values ​​of the three components of the test surface (release layer surface) were determined by solving the simultaneous equations obtained by substituting the known values ​​and θ into the above formula.

[0128] The surface free energy (E) was calculated by adding the calculated dispersion force component, polar force component, and hydrogen bonding force component values ​​according to the following formula: E = γSd + γSp + γSh.

[0129] (2) Measurement of Peel Force (2-1) Peel Force (1): Peel Force of Acrylic Pressure-Sensitive Adhesive Tape The adhesive surface of a 50 mm wide acrylic pressure-sensitive adhesive tape (Nitto Denko Corporation's "No. 31B") was laminated to the release layer surface of a release sheet by pressing it with a rubber roller having a weight of 5 kg and moving it back and forth once, and after leaving it at room temperature (23±2°C) for 24 hours, the peel force was measured when the adhesive tape side was peeled off at an angle of 180° at a speed of 300 mm / min using a tensile tester (A&D Corporation's "Tensilon RTC-1210A" product number).

[0130] (2-2) Peeling force (2): Peeling force of silicone-based pressure-sensitive adhesive tape The peeling force was measured in the same manner as in (2-1) above, except that the acrylic pressure-sensitive adhesive tape was changed to a silicone-based pressure-sensitive adhesive tape ("Kapton (registered trademark)" tape No. 650S#25 manufactured by Teraoka Seisakusho Co., Ltd.).

[0131] (3) Measurement of Young's modulus: A test piece was prepared by cutting the release sheet into a strip of 150 mm x 10 mm. This test piece was set in a tensile tester with a chuck distance of 100 mm, and a tensile test was started at a tensile speed of 50 mm / min. Five points in the small deformation region (within 5% strain) were selected from the obtained stress (vertical axis) - strain (horizontal axis) curve, and the Young's modulus was calculated from the slope obtained from a linear approximation equation.

[0132] (4) Measurement of the thickness of the substrate and the release sheet The substrate and the release sheet were cut into A4 size samples, and the thickness was measured at any five 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 substrate thickness.

[0133] (5) Peeling Feel (5-1) Peeling Feel (1): Peeling Feel of Acrylic Pressure-Sensitive Adhesive Tape The adhesive surface of an acrylic pressure-sensitive adhesive tape (Nitto Denko Corporation's "No. 31B") was applied to the release layer surface of a release sheet by pressing it back and forth with a rubber roller weighing 5 kg, and then left for 24 hours at room temperature (23±2°C). After that, while still holding the adhesive tape, the release sheet was pinched with the fingers and peeled off. The peeling feel at this time was evaluated according to the following criteria. A: Low resistance B: Slightly high resistance C: High resistance

[0134] (5-2) Peeling Feel (2): Peeling Feel of Silicone-Based Pressure-Sensitive Adhesive Tape The same evaluation was conducted as in (5-1) above, except that the acrylic pressure-sensitive adhesive tape was replaced with a silicone-based pressure-sensitive adhesive tape ("Kapton (registered trademark)" Tape No. 650S#25 manufactured by Teraoka Seisakusho Co., Ltd.).

[0135] (6) Measurement of Whiteness of White Substrates Using a colorimetric color difference meter (ZE2000, manufactured by Nippon Denshoku Industries Co., Ltd.) and standard illuminant C, the whiteness is measured by the Hunter method described in JIS Z 8722 (2000) and JIS L 1015 (2010). Using values ​​expressed in the Lab color system, the whiteness is calculated using the following formula. Three measurements were taken and the average was calculated: 100 - [(100 - L)] ２ +a ２ +b ２ ] １／２ = Whiteness (%).

[0136] [Substrate] The following polyester film (polyethylene terephthalate film) was prepared as the substrate.

[0137] <Polyester film 1> A 50 μm thick white polyester film (Lumirror (registered trademark) E20) manufactured by Toray Industries, Inc. was used. The whiteness of this white polyester film was 93.

[0138] <Polyester Film 2> A polyester film ("Lumirror (registered trademark)" S28) manufactured by Toray Industries, Inc. having a thickness of 50 μm was used.

[0139] <Polyester Film 3> A polyester film ("Lumirror (registered trademark)" S28) manufactured by Toray Industries, Inc. having a thickness of 23 μm was used.

[0140] <Polyester Film 4> A polyester film (Lumirror (registered trademark) S28) manufactured by Toray Industries, Inc. having a thickness of 188 μm was used.

[0141] <Polyester Film 5> A polyester film (Lumirror (registered trademark) S28) manufactured by Toray Industries, Inc. having a thickness of 18 μm was used.

[0142] <Polyester Film 6> A polyester film ("Lumirror (registered trademark)" S28) manufactured by Toray Industries, Inc. having a thickness of 250 μm was used.

[0143] [Release Layer Forming Composition] The following composition was prepared.

[0144] <Active energy ray-curable composition p1> 25 parts by mass of the polymerizable long-chain alkyl compound (A1) synthesized as described below, 75 parts by mass of dipentaerythritol hexaacrylate (trade name "DPHA" manufactured by Daicel Cytec Co., Ltd.) as the polymerizable compound (C), and 10 parts by mass of a photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.) were charged, heated to 100°C, and mixed for 1 hour. Further, a mixed solvent of toluene and isopropyl alcohol (IPA) (toluene:IPA=3:1 (mass ratio)) was added so that the solids concentration became 4% by mass.

[0145] <Synthesis of Polymerizable Long-Chain Alkyl Compound (A1)> A flask equipped with a stirrer and a thermometer was charged with 100 parts by mass of 2-hydroxyethyl acrylate ("BHEA" manufactured by Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound having a hydroxyl group, 240 parts by mass of diphenylmethane diisocyanate ("Millionate MT" manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound, and 25 parts by mass of hexadecanol ("1-Hexadecanol" manufactured by Tokyo Chemical Industry Co., Ltd.) as a higher alcohol, and the mixture was heated to 100°C and kept at that temperature for 7 hours to react. The reaction was terminated when it was confirmed by IR measurement that the isocyanate groups had disappeared.

[0146] <Active energy ray-curable composition p2> 25 parts by mass of the polymerizable long-chain alkyl compound (A2) synthesized as described below, 75 parts by mass of dipentaerythritol hexaacrylate (trade name "DPHA" manufactured by Daicel Cytec Co., Ltd.) as the polymerizable compound (C), and 10 parts by mass of a photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.) were charged, heated to 100°C, and mixed for 1 hour. Further, a mixed solvent of toluene and isopropyl alcohol (IPA) (toluene:IPA=3:1 (mass ratio)) was added so that the solids concentration became 4% by mass.

[0147] <Synthesis of Polymerizable Long-Chain Alkyl Compound (A2)> A flask equipped with a stirrer and a thermometer was charged with 100 parts by mass of 2-hydroxyethyl acrylate ("BHEA" manufactured by Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound having a hydroxyl group, 240 parts by mass of diphenylmethane diisocyanate ("Millionate MT" manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound, and 26 parts by mass of stearyl alcohol ("Conol 30SS" manufactured by New Japan Chemical Co., Ltd.) as a higher alcohol, and the mixture was heated to 100°C and kept at that temperature for 7 hours to react. The reaction was terminated when it was confirmed by IR measurement that the isocyanate groups had disappeared.

[0148] <Active energy ray-curable composition p3> 15 parts by mass of the polymerizable long-chain alkyl compound (A3) synthesized below, 85 parts by mass of dipentaerythritol hexaacrylate (trade name "DPHA" from Daicel Cytec Co., Ltd.) as the polymerizable compound (c), and 10 parts by mass of a photopolymerization initiator ("Irgacure" (registered trademark) 184 from Ciba Specialty Chemicals Co., Ltd.) were charged, heated to 100°C, and mixed for 1 hour to obtain an active energy ray-curable composition. This composition was then adjusted to a solids concentration of 4% by mass with a mixed solvent of toluene and isopropyl alcohol (toluene:IPA = 3:1 (mass ratio)).

[0149] (Synthesis of Polymerizable Long-Chain Alkyl Compound (A3)) A flask equipped with a stirrer and a thermometer was charged with 100 parts by mass of 2-hydroxyethyl acrylate ("BHEA" available from Nippon Shokubai Co., Ltd.) as a (meth)acrylate compound (d) having a hydroxyl group, 86 parts by mass of hexamethylene diisocyanate (trade name "HDI" available from Nippon Polyurethane Co., Ltd.) as a polyisocyanate compound (e), and 46 parts by mass of stearyl alcohol ("Conol" (registered trademark) 30SS available from New Japan Chemical Co., Ltd.) as a higher alcohol (f), and the mixture was heated to 100°C and kept at that temperature for 7 hours to react. The reaction was terminated when it was confirmed by IR measurement that the isocyanate groups had disappeared.

[0150] <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 crosslinker ("Tesfine 303" manufactured by Hitachi Chemical Co., Ltd.) Acid catalyst c: 0.3 parts by mass, in terms of solid content, of p-toluenesulfonic acid ("Dryer 900" manufactured by Hitachi Chemical Co., Ltd.) Solvent: A mixed solvent (toluene:methyl ethyl ketone:cyclohexanone = 45:45:10 (mass ratio)) adjusted to a solid content concentration of 2.0% by mass.

[0151] <Thermosetting composition q2> Long-chain alkyl compound: 5 parts by mass of long-chain alkyl group-containing polyvinyl resin ("Peiroil" (registered trademark)) 1050, manufactured by Lion Specialty Chemicals Co., Ltd.) converted to solids Crosslinking agent: 68 parts by mass of melamine compound ("Yuban" (registered trademark) 28-60, manufactured by Mitsui Chemicals, Inc.) converted to solids Acid catalyst: 5 parts by mass of p-toluenesulfonic acid ("TAYCACURE" AC-707, manufactured by Teika Corporation) converted to solids Solvent: mixed solvent (toluene:methyl ethyl ketone:cyclohexanone = 45:45:10 (mass ratio)) adjusted to a solids concentration of 2.0 mass% <Thermosetting composition q3> Melamine compound ("ATOM BOND" RP-50, manufactured by Mitsuba Research Institute Co., Ltd.) converted to solids 10 parts by mass Acid catalyst: 2.0 parts by mass of an isocyanate compound (Washin Chemical Industry Co., Ltd. "Plus Coat ST" DEP Clear) converted to solid content. Solvent: A mixed solvent (toluene:cyclohexanone:methanol = 50:40:10 (mass ratio)) adjusted to a solid content concentration of 5.0 mass%.

[0152] <Thermosetting composition q4> Melamine compound (Mitsui Chemicals, Inc., "Yuvan" 28-60), 70 parts by mass in terms of solid content Acid catalyst: p-toluenesulfonic acid (Tayca Corporation, "TAYCACURE" AC-707), 5 parts by mass 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 mass%.

[0153] [Formation of printed ink layer] A 2.0 mm grid pattern was gravure printed on one side of Polyester Film 1 using black ink (V515UR black ink, manufactured by Toyo Ink Mfg. Co., Ltd.). The area ratio of the printed area was 15%. In the same manner as above, printed ink layers were provided on one side of Polyester Films 2 to 6.

[0154] [Example 1] A polyester film 1 provided with a printed ink layer was used as a substrate. An active energy ray-curable composition p1 was applied onto the printed ink layer of this polyester film 1 using a gravure coater, and after drying at a temperature of 80°C, ultraviolet rays were applied at 300 mJ / cm ２ The coating was irradiated and cured to form a release layer having a thickness of 200 nm, thereby producing a release sheet.

[0155] A release layer was formed in the same manner as above on one surface of the polyester film 1 on which no printing had been performed, to prepare a release sheet (reference example).

[0156] Example 2 A release sheet was prepared in the same manner as in Example 1, except that the active energy ray-curable composition was changed to p2.

[0157] Example 3 A release sheet was prepared in the same manner as in Example 1, except that the active energy ray-curable composition was changed to p3.

[0158] [Example 4] Thermosetting composition q1 was applied onto the printing ink layer of polyester film 1 using a gravure coater, and then heated and dried at 160°C for 30 seconds to form a release layer, thereby producing a release sheet. The thickness of the release layer was 200 nm.

[0159] Example 5 and Comparative Examples 1 and 2 Release sheets were prepared in the same manner as in Example 1, except that the release layer-forming composition was changed as shown in Table 1.

[0160] [Example 6] In Example 1, a resin layer (acrylic polyol / isocyanate-based ink "V425 Anchor" manufactured by Toyo Ink Co., Ltd.) was applied onto the printed ink layer using a gravure coater to a dry film thickness of 1 μm, and then dried at 80° C. for 1 minute to form a resin layer. The surface free energy of this resin layer was 43 mN / m. Furthermore, a release layer was laminated onto the resin layer in the same manner as in Example 1 to produce a release sheet.

[0161] [Evaluation] The surface free energy and peel strength of the release layer of each of the release sheets prepared above were measured. The results are shown in Table 1.

[0162]

[0163] Examples 11 to 16 A resin layer and a release layer were formed on the printed ink layer of each of the printed polyester films 1 to 6 in the same manner as in Example 5 to prepare a release sheet.

[0164] [Evaluation] The release force and release feel of the release sheets prepared above were measured. The results are shown in Table 2.

[0165]

[0166] REFERENCE SIGNS LIST 1, 2 Release sheet 11 Substrate 12 Printed ink layer 12a Printed portion 12b Non-printed portion 13 Release layer (A) 14 Resin layer 15 Release layer (B) 20, 30 Pressure-sensitive adhesive member with release sheet 21, 31 Adhesive layer 40 Double-sided pressure-sensitive adhesive sheet 41 Support 42, 43 Adhesive layer 100 Double-sided pressure-sensitive adhesive sheet with release sheet

Claims

1. A release sheet having a printed ink layer on a substrate and a release layer (A) on the printed ink layer, wherein the printed ink layer has printed areas and non-printed areas, and the release layer (A) contains a compound having an alkyl group with 8 or more carbon atoms.

2. The release sheet according to claim 1, wherein the release layer (A) is a cured layer of an active energy ray-curable composition containing a compound having an alkyl group with 8 or more carbon atoms, or a cured layer of a thermosetting composition containing a compound having an alkyl group with 8 or more carbon atoms.

3. The release sheet according to claim 2, wherein the release layer (A) is a cured layer of an active energy ray-curable composition.

4. The release sheet according to claim 3, wherein the active energy ray-curable composition contains a polymerizable long-chain alkyl compound (a), which is a compound having an ethylenically unsaturated group and an alkyl group having 8 or more carbon atoms in the molecule.

5. A release sheet according to claim 3 or 4, wherein the active energy ray-curable composition further contains a polymerizable compound (c) which is a compound having an ethylenically unsaturated group in the molecule and not having an alkyl group having 8 or more carbon atoms.

6. The release sheet according to claim 1, which has a resin layer between the printing ink layer and the release layer (A).

7. The release sheet according to claim 6, wherein the surface free energy of said resin layer is greater than the surface free energy of said release layer (A).

8. The release sheet according to claim 6, wherein the surface free energy of the resin layer is 30 mN / m or more and 70 mN / m or less.

9. The release sheet according to claim 1, wherein the surface free energy of the release layer (A) is 17 mN / m or more and less than 43 mN / m.

10. The release sheet according to claim 1, wherein the peel strength between the release layer (A) and the adhesive tape is 0.2 N / 50 mm or more and less than 8 N / 50 mm.

11. The release sheet according to claim 1, wherein the product of Young's modulus (MPa) and thickness (μm) of the release sheet is 30,000 MPa·μm or more and less than 300,000 MPa·μm.

12. The release sheet according to claim 1, wherein the substrate is a plastic film.

13. The release sheet according to claim 1, wherein the substrate is a white plastic film.

14. The release sheet of claim 12, wherein the plastic film is a polyester film.

15. The release sheet according to claim 1, which has a release layer (B) on the side of the substrate opposite to the release layer (A).

Images