Adhesive sheet and method for manufacturing an adhesive sheet

Abstract

Provided is an adhesive sheet 1 comprising: a base material 11 formed from a paper material; and an adhesive layer 12 laminated on at least one surface of the base material 11, wherein an adhesive constituting the adhesive layer 12 contains a cyclodextrin derivative. The total light transmittance of the adhesive sheet 1 is preferably 50% or less. Moreover, the gel fraction of the adhesive is preferably 10% or less. Furthermore, a total light transmittance change amount (points) obtained by subtracting the total light transmittance (%) of only the base material from the total light transmittance (%) of a laminate comprising the base material 11 and the adhesive layer 12 is preferably from 0 points to 20 points, inclusive. Through the adhesive sheet 1, good fixability to an adherend can be exhibited, and the adhesive layer can be recycled.

Description

[Technical Field]

[0001] The present invention relates to adhesive sheets and methods for manufacturing adhesive sheets, and more particularly to recyclable adhesive sheets and methods for manufacturing adhesive sheets. [Background technology]

[0002] In recent years, there has been a growing demand for the creation of a circular economy, and recyclability is being required for various products and materials.

[0003] Incidentally, novel materials utilizing cyclodextrin monomers have recently been proposed. Specifically, Patent Document 1 proposes a polymer material comprising a crosslinked polymer formed by the interaction of a host group and a guest group, wherein the host group is a monovalent group obtained by removing one hydrogen atom or one hydroxyl group from cyclodextrin, and the crosslinked polymer comprises a predetermined repeating structural unit.

[0004] Furthermore, Patent Document 2 proposes an inclusion complex formed from a host group of a host group-containing monomer and a guest group of a guest group-containing monomer, wherein the host group-containing monomer is a cyclodextrin monomer derivative having a (meth)acryloyl group, and the guest group-containing monomer is a predetermined monomer having a vinyl group. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6636610 [Patent Document 2] Patent No. 6239043 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Given the background described above, it is desirable that the adhesive layer of the adhesive sheet also be recyclable. However, Patent Documents 1 and 2 do not contain any description of the adhesive of the adhesive sheet, nor do they mention anything about recyclability.

[0007] By the way, adhesive sheets are used to fix various objects, but the surface shape of the object varies depending on the object, such as being flat or curved. Adhesive sheets are required to be able to fix objects well regardless of whether they are flat or curved.

[0008] This invention has been made in view of the above circumstances, and aims to provide an adhesive sheet and a method for manufacturing the same that can exhibit good fixation to an adherend and whose adhesive layer can be recycled. [Means for solving the problem]

[0009] To achieve the above objective, firstly, the present invention provides an adhesive sheet comprising a base material made of a paper-based material and an adhesive layer laminated on at least one side of the base material, wherein the adhesive constituting the adhesive layer contains a cyclodextrin derivative (Invention 1).

[0010] In the above invention (Invention 1), the adhesive constituting the adhesive layer contains a cyclodextrin derivative, thereby enabling good fixation to the adherend and allowing for the recycling of the adhesive (layer).

[0011] In the above invention (Invention 1), it is preferable that the total light transmittance is 50% or less (Invention 2).

[0012] In the above inventions (Inventions 1 and 2), it is preferable that the gel fraction of the adhesive is 10% or less (Invention 3).

[0013] In the above inventions (Inventions 1 to 3), it is preferable that the change in total light transmittance (points) obtained by subtracting the total light transmittance (%) of the substrate alone from the total light transmittance (%) of the laminate consisting of the substrate and the adhesive layer is 0 points or more and 20 points or less (Invention 4).

[0014] In the above inventions (Inventions 1 to 4), it is preferable that the following relational expression (I) is satisfied when the mass per unit area of ​​the substrate is N1 (mg), the mass of the substrate obtained by immersing a unit area of ​​the substrate in a solvent that dissolves the adhesive layer during recycling for 72 hours and then drying it is N2 (mg). 0≦(N1-N2) / N1≦0.1 (I)

[0015] In the above inventions (Inventions 1 to 5), it is preferable that the holding force in accordance with JIS Z0237:2009 is 20 mm or less, measured as a displacement of 20 mm or less when the bonding area to the soda-lime glass is 25 mm x 25 mm, the test temperature is 23°C, the standing time is 24 hours, and a load of 40 g is applied (Invention 6).

[0016] In the above inventions (Inventions 1 to 6), it is preferable that the adhesive force to soda-lime glass is 1 N / 25 mm or more (Invention 7).

[0017] In the above inventions (Inventions 1 to 7), when the mass per unit area of ​​the adhesive sheet is M1 (mg), and the mass of the adhesive sheet obtained by immersing the adhesive sheet per unit area in a solvent that dissolves the adhesive layer during recycling for 72 hours and then drying is M2 (mg), and the mass per unit area of ​​the substrate is N1 (mg), and the mass of the substrate obtained by immersing the substrate per unit area in a solvent that dissolves the adhesive layer during recycling for 72 hours and then drying is N2 (mg), it is preferable that the adhesive mass reduction rate (%) calculated by the following formula (II) is 80% or more (Invention 8). Adhesive mass reduction rate (%)={1-(N1-N2) / (M1-M2)}×100...(II)

[0018] In the above inventions (Inventions 1 to 8), it is preferable that the adhesive contains a polymer having a main chain obtained by copolymerizing an acrylic monomer and a cyclodextrin derivative having a polymerizable group (Invention 9).

[0019] In the above invention (Invention 9), it is preferable that the polymerizable group of the cyclodextrin derivative is a group containing a polymerizable unsaturated double bond (Invention 10).

[0020] In the above inventions (Inventions 1 to 10), it is preferable that the weight average molecular weight of the sol fraction of the adhesive by gel permeation chromatography is 50,000 or more and 1,400,000 or less (Invention 11).

[0021] Second, the present invention provides a method for producing an adhesive sheet, characterized in that an adhesive composition containing an acrylic monomer and a cyclodextrin derivative having a polymerizable group is applied to at least one side of a base material made of a paper-based material to form a coating film, and the coating film is irradiated with active energy rays to copolymerize the acrylic monomer and the cyclodextrin derivative to form an adhesive layer (Invention 12).

Advantages of the Invention

[0022] The adhesive sheet according to the present invention can exhibit good fixing property to an adherend, and the adhesive layer of the adhesive sheet can be recycled. Further, according to the method for producing an adhesive sheet of the present invention, an adhesive sheet that can exhibit good fixing property to an adherend and whose adhesive layer can be recycled can be produced.

Brief Description of the Drawings

[0023] [Figure 1] It is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described. An adhesive sheet according to one embodiment of the present invention comprises a base material made of a paper-based material and an adhesive layer laminated on at least one side of the base material, wherein the adhesive constituting the adhesive layer contains a cyclodextrin derivative.

[0025] In the adhesive sheet according to this embodiment, the adhesive constituting the adhesive layer contains a cyclodextrin derivative, making the adhesive recyclable. That is, by immersing the adhesive sheet according to this embodiment in a predetermined solvent, the adhesive dissolves in the solvent and detaches from the substrate. The adhesive dissolved in the solvent can be reused by volatilizing the solvent. Furthermore, if the substrate is made of a material with low solubility in the solvent, the substrate can also be reused.

[0026] The solvent used to dissolve the adhesive (layer) during recycling is not particularly limited, but examples include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0027] Furthermore, in the adhesive sheet according to this embodiment, the adhesive constituting the adhesive layer contains a cyclodextrin derivative, which enables good fixation to the adherend. In other words, the adhesive sheet according to this embodiment exhibits good adhesive strength and holding power, enabling good adhesion not only to flat surfaces but also to adherends having curved surfaces, for example.

[0028] Thus, the adhesive sheet according to this embodiment, by containing a cyclodextrin derivative in the adhesive layer, can exhibit good fixation to the adherend and the adhesive can be recycled.

[0029] Figure 1 shows a specific configuration of an example of an adhesive sheet according to this embodiment. As shown in Figure 1, the adhesive sheet 1 according to this embodiment consists of a base material 11, an adhesive layer 12 laminated on one side of the base material 11, and a release sheet 13 laminated on the side of the adhesive layer 12 opposite to the base material 11. The release sheet 13 is laminated on the adhesive layer 12 such that its release surface is in contact with the adhesive layer 12. In this specification, the release surface of the release sheet refers to the surface of the release sheet that has release properties, and includes both surfaces that have undergone a release treatment and surfaces that exhibit release properties even without a release treatment.

[0030] 1. Components 1-1. Base material In this embodiment, the base material 11 is made of a paper-based material. Specifically, examples of paper-based materials include fine paper, glassine paper, kraft paper, art paper, coated paper, laminated paper, etc. Among these, from the viewpoint of the recyclability of the base material 11 itself, paper that does not use synthetic resins, such as fine paper and kraft paper, is preferred, and fine paper with strength suitable for recycling is particularly preferred.

[0031] When recycling the adhesive sheet 1 according to this embodiment, it is preferable to immerse the adhesive sheet 1 in a solvent that dissolves the adhesive layer. At this time, it is preferable that the base material 11 does not dissolve as much as possible in the solvent, thereby improving the recyclability of both the adhesive and the base material 11. Specifically, when the mass per unit area of ​​the base material 11 is N1 (mg), and the mass of the base material after immersing the above unit area in a solvent that dissolves the adhesive layer during recycling (methyl ethyl ketone is used in the test example) for 72 hours and then drying is N2 (mg), it is preferable that the following relational expression (I) is satisfied. 0≦(N1-N2) / N1≦0.1 (I)

[0032] The value of the right-hand side in the above relation (I) is preferably ≤0.05, more preferably ≤0.03, particularly preferably ≤0.02, and even more preferably ≤0.01.

[0033] The thickness of the substrate 11 is preferably 0.1 to 500 μm, more preferably 1 to 300 μm, particularly preferably 10 to 200 μm, even more preferably 30 to 100 μm, and most preferably 50 to 80 μm. Having the substrate 11 thickness within this range results in good recyclability and excellent handling properties.

[0034] The total light transmittance of the substrate 11 (substrate 11 before lamination of the adhesive layer 12) is preferably 90% or less, more preferably 80% or less, particularly preferably 60% or less, even more preferably 40% or less, and most preferably 30% or less. This allows for opacity, making it suitable for use in labels and the like where opacity is required. The lower limit of the total light transmittance may be 0%, but is usually preferably 5% or more, more preferably 10% or more, particularly preferably 15% or more, and even more preferably 20% or more.

[0035] In the adhesive sheet according to this embodiment, it is preferable that the change in total light transmittance (points) obtained by subtracting the total light transmittance (%) of the substrate (substrate before lamination of the adhesive layer) from the total light transmittance (%) of the laminate consisting of the substrate and the adhesive layer is between 0 points and 20 points. This allows the opacity of the substrate 11 to be fully exhibited, making it suitable for use in labels and the like where opacity is required. The total light transmittance in this specification is a value measured in accordance with JIS K7361-1:1997.

[0036] From the viewpoint of opacity, the change in total light transmittance is more preferably 15 points or less, particularly preferably 7 points or less, and even more preferably 3 points or less.

[0037] 1-2. Adhesive layer As described above, the adhesive constituting the adhesive layer 12 contains a cyclodextrin derivative, and preferably a polymer in which the cyclodextrin derivative is a constituent monomer.

[0038] The gel fraction of the adhesive is preferably 10% or less, more preferably 8% or less, particularly preferably 5% or less, and even more preferably 3% or less. A lower gel fraction of the adhesive allows the adhesive to dissolve more easily into the solvent when the adhesive sheet 1 is immersed in the solvent, thereby making the adhesive layer 12 more easily dissolved and detached, resulting in superior recyclability. On the other hand, the lower limit of the gel fraction is most preferably 0%, but in practice it is preferably 0.01% or more, more preferably 0.05% or more, particularly preferably 0.1% or more, and even more preferably 0.2% or more. The method for measuring the gel fraction in this specification is as shown in the test examples described later.

[0039] The above adhesive preferably contains a polymer having a main chain obtained by copolymerizing an acrylic monomer with a cyclodextrin derivative having polymerizable groups. This allows the adhesive to exhibit the desired adhesive strength and holding power, and also makes it easier to reuse the adhesive that has leached into the solvent during recycling, resulting in improved recyclability of the adhesive.

[0040] Preferably, the above adhesive does not contain guest molecules that can be encapsulated in the cyclodextrin derivative. In this specification, encapsulation refers to the phenomenon in which a guest molecule is incorporated into the cavity of a host molecule (cyclodextrin derivative). In this specification, a guest molecule refers to a molecule that can be encapsulated in a cyclodextrin derivative, and includes molecules that have not yet been encapsulated. Examples of such guest molecules for α-cyclodextrin derivatives include n-butyl acrylate, styrene, octyl acrylate, and dodecyl acrylate; for β-cyclodextrin derivatives, examples include n-butyl acrylate, t-butyl acrylate, styrene, adamantyl acrylate, and isobornyl acrylate; and for γ-cyclodextrin derivatives, examples include octyl acrylate and dodecyl acrylate.

[0041] In this specification, when an adhesive is described as "not containing guest molecules that can be encapsulated in a cyclodextrin derivative," it means that it substantially does not contain such molecules. Specifically, the adhesive may contain guest molecules in an amount of 1 mol or less, preferably 0.1 mol or less, particularly preferably 0.01 mol or less, and even more preferably 0.001 mol or less, per 100 mol of the total amount of acrylic monomer. For example, the monomers listed above may be used as the acrylic monomer, and these monomers basically become polymers through polymerization and do not become guest molecules that can be encapsulated, but since small amounts may remain after polymerization, the above definition is used.

[0042] The polymer having a main chain obtained by copolymerizing the above-mentioned acrylic monomer with a cyclodextrin derivative having polymerizable groups preferably does not have a branched structure. This prevents the resulting adhesive from becoming too dense, making it easier to satisfy the aforementioned gel fraction.

[0043] The above adhesive layer is preferably formed from an adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing an acrylic monomer (A), a cyclodextrin derivative (B) having polymerizable groups, and preferably a photopolymerization initiator (C). A polymer having a main chain copolymerized from an acrylic monomer (A) and a cyclodextrin derivative (B) may be referred to as "polymer Q" below.

[0044] (1) Each component (1-1) Acrylic monomer (A) In this embodiment, the acrylic monomer (A) is preferably a monofunctional acrylic monomer. This makes it possible to make the polymer Q of the acrylic monomer (A) and the cyclodextrin derivative (B) without a branched structure, and the aforementioned gel fraction is more easily satisfied.

[0045] Examples of acrylic monomers (A) in this embodiment include (meth)acrylic acid esters, (meth)acrylic acid, (meth)acrylamide, vinyl acetate, styrene, etc., with (meth)acrylic acid esters being preferred. Acrylic monomers (A) may be used individually or in combination of two or more. In this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0046] Examples of (meth)acrylic acid esters include alkyl (meth)acrylates in which the alkyl group is linear or branched, cyclic (meth)acrylic acid esters having a cyclic structure such as an alicyclic structure, and (meth)acrylic acid esters having a functional group such as a hydroxyl group. Among these, alkyl (meth)acrylates in which the alkyl group is linear or branched are preferred.

[0047] Of the alkyl (meth)acrylate esters mentioned above, alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group are preferred from the viewpoint of adhesiveness. Examples of alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among these, from the viewpoint of good adhesiveness, alkyl (meth)acrylate esters with 1 to 8 carbon atoms in the alkyl group are preferred, and methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are more preferred. From the viewpoint of recyclability, methyl methacrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are particularly preferred, and ethyl acrylate and n-butyl acrylate are even more preferred.

[0048] Ethyl acrylate and n-butyl acrylate can also be used in combination, in which case they are preferably used in a mass ratio of 0.01:0.99 to 0.99:0.01, more preferably in a mass ratio of 1:99 to 99:1, particularly preferably in a mass ratio of 5:95 to 95:5, even more preferably in a mass ratio of 10:90 to 90:10, and most preferably in a mass ratio of 20:80 to 80:20.

[0049] (1-2) Cyclodextrin derivatives (B) In this embodiment, the cyclodextrin portion of the polymerizable cyclodextrin derivative (B) is preferably α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin, and in particular, from the viewpoint of solvent solubility, it is preferably β-cyclodextrin or γ-cyclodextrin.

[0050] The polymerizable group of the cyclodextrin derivative (B) is not particularly limited as long as it can polymerize with the acryloyl group of the acrylic monomer (A), but it is preferably a group containing a polymerizable unsaturated double bond, more preferably an ethylenically unsaturated group, and specifically preferably a (meth)acryloyl group, vinyl group, allyl group, etc., and is particularly preferably a (meth)acryloyl group.

[0051] Furthermore, it is preferable that the polymerizable group of the cyclodextrin derivative (B) be one per cyclodextrin molecule. This makes it possible to form polymer Q of the acrylic monomer (A) and cyclodextrin derivative (B) without a branched structure, and thus makes it easier to satisfy the gel fraction described above.

[0052] From the above viewpoint, it is preferable that the content of cyclodextrin derivatives having two or more polymerizable groups per molecule in the adhesive composition P be small. Specifically, it is preferable that it be 0.1% by mass or less, particularly 0.01% by mass or less, and even more preferably 0.001% by mass or less.

[0053] In this embodiment, the cyclodextrin derivative (B) is preferably a compound represented by the following formula (1). [ka] (R in equation (1) above) 1 R represents a hydrogen atom or a methyl group. 2 '' represents a hydrocarbon containing O, NH, or O, a hydrocarbon containing NH, or a hydrocarbon containing both O and NH. 'CD' represents α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin.

[0054] Examples of the above-mentioned "hydrocarbons containing NH" include -CH2-NH-CH2-, -O-CH2-NH-CH2-, -CH2-NH-CH2-O-, -O-CH2-NH-CH2-O-, -CH2-O-CO-NH-CH2-O-, and -CH2-O-CO-NH-C2H4-O-.

[0055] The content of cyclodextrin derivative (B) in the adhesive composition P is preferably 0.01 to 10, more preferably 0.1 to 7, particularly preferably 0.5 to 4, and even more preferably 0.8 to 2, when the total amount of acrylic monomer (A) is 100 mol. By having the content of cyclodextrin derivative (B) within the above range, the recyclability is improved and good adhesiveness is obtained.

[0056] (1-3) Photopolymerization initiator (C) When ultraviolet light is used as the active energy ray for copolymerizing an acrylic monomer (A) and a cyclodextrin derivative (B) having a polymerizable group, it is preferable that the adhesive composition P further contains a photopolymerization initiator (C). By including the photopolymerization initiator (C) in this way, the acrylic monomer (A) can be copolymerized efficiently without remaining in the adhesive, and the polymerization curing time and the amount of active energy ray irradiation can be reduced.

[0057] Examples of such photopolymerization initiators (C) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, Examples include 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. These may be used individually or in combination of two or more.

[0058] The content of the photopolymerization initiator (C) in the adhesive composition P is preferably such that the molar ratio of the acrylic monomer (A) and cyclodextrin derivative (B) is 0.001 to 10, more preferably 0.01 to 1, most preferably 0.02 to 0.5, particularly preferably 0.05 to 0.3, and even more preferably 0.1 to 0.2, when the total amount of acrylic monomer (A) and cyclodextrin derivative (B) is 100 mol. As a result, the resulting adhesive layer is more likely to satisfy the aforementioned physical properties and exhibit good recyclability.

[0059] (1-4) Various additives The adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as silane coupling agents, rust inhibitors, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, refractive index adjusters, and fillers.

[0060] (2) Physical properties (2-1) Weight-average molecular weight of the sol The weight-average molecular weight of the sol portion of the above adhesive, as determined by gel permeation chromatography, is preferably 1.4 million or less, more preferably 1.2 million or less, particularly preferably 1 million or less, even more preferably 800,000 or less, and most preferably 600,000 or less. This makes it easier for the adhesive to dissolve into the solvent when the adhesive sheet is immersed in the solvent, resulting in improved recyclability of the adhesive. Furthermore, the weight-average molecular weight is preferably 50,000 or more, more preferably 100,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. This makes it easier to reuse the adhesive that has dissolved into the solvent. The specific method for measuring the weight-average molecular weight of the sol portion is shown in the test examples described later.

[0061] (2-2) Haze value of the adhesive layer The haze value of the adhesive layer 12 in the adhesive sheet 1 according to this embodiment is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, and even more preferably 0.5% or less. This results in an adhesive layer 12 with excellent transparency, making it easier to satisfy the preferred total light transmittance of the adhesive layer 12 and the adhesive sheet 1, and also tends to easily satisfy the aforementioned change in total light transmittance. The lower limit of the haze value may be 0%, but from the viewpoint of easily satisfying the aforementioned change in total light transmittance, it is preferably 0.01% or more, more preferably 0.1% or more, particularly preferably 0.2% or more, and even more preferably greater than 0.2%. The specific method for measuring the haze value is as shown in the test examples described later.

[0062] (2-3) Total light transmittance of the adhesive layer The total light transmittance of the adhesive layer 12 in the adhesive sheet 1 according to this embodiment is preferably 40 to 100%, more preferably 60 to 99%, particularly preferably 80 to 96%, and even more preferably 90 to 94%, from the viewpoint of easily satisfying the value of the change in total light transmittance described above.

[0063] (2-4) Thickness of the adhesive layer The thickness of the adhesive layer 12 in the adhesive sheet 1 according to this embodiment (a value measured in accordance with JIS K7130) is preferably 1 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more, even more preferably 10 μm or more, and most preferably 15 μm or more. This allows the desired adhesive strength and holding power to be achieved. Furthermore, the thickness of the adhesive layer 12 is preferably 100 μm or less, more preferably 75 μm or less, particularly preferably 50 μm or less, even more preferably 40 μm or less, and most preferably 30 μm or less. This makes it easier for the adhesive layer 12 to detach from the substrate 11 when the adhesive sheet 1 is immersed in a solvent, resulting in improved recyclability of the adhesive and the substrate 11. In addition, the adhesive sheet 1 is more likely to satisfy the aforementioned change in total light transmittance. The adhesive layer 12 may be formed as a single layer or as multiple layers laminated together.

[0064] 1-3. Release Sheet The release sheet 13 protects the adhesive layer 12 until the adhesive sheet 1 is used, and is peeled off when the adhesive sheet 1 (adhesive layer 12) is used. In the adhesive sheet 1 according to this embodiment, the release sheet 13 is not necessarily required.

[0065] Preferably used as the release sheet 13 are plastic films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin film. Crosslinked films of these can also be used. Furthermore, laminated films of these may also be used.

[0066] It is preferable that the release surface of the release sheet 13 (particularly the surface in contact with the adhesive layer 12) is subjected to a release treatment. Examples of release agents used in the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax-based release agents.

[0067] There are no particular restrictions on the thickness of the release sheet 13, but it is usually around 20 to 200 μm.

[0068] 2. Method for manufacturing adhesive sheets To manufacture the adhesive sheet 1 according to this embodiment, first, preferably an adhesive composition P is prepared. Specifically, an acrylic monomer (A), a cyclodextrin derivative (B), a photopolymerization initiator (C) if desired, and additives are mixed. It is preferable that the adhesive composition P does not contain a solvent (water, organic solvent, etc.).

[0069] Next, the adhesive composition P is applied to one side of the substrate 11 to form a coating layer. Methods for applying the adhesive composition P include, for example, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0070] Once the adhesive composition P coating layer is formed, a release sheet 13 is laminated onto the coating layer so that its release surface is in contact with the coating layer. Then, the coating layer is irradiated with active energy rays to copolymerize the acrylic monomer (A) and the cyclodextrin derivative (B) to form an adhesive layer.

[0071] Active energy rays refer to electromagnetic waves or charged particle beams that possess energy quanta, specifically including ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0072] Ultraviolet irradiation can be performed using high-pressure mercury lamps, Heraeus H lamps, xenon lamps, etc., with an illuminance of 50-1000 mW / cm². 2 Preferably, the intensity is 100-500 mW / cm². 2 It is preferable that the light intensity be 50 to 10,000 mJ / cm². 2 Preferably, the concentration is 200-7000 mJ / cm². 2 It is more preferable that the concentration be 500-3000 mJ / cm². 2 It is particularly preferable that this is the case. On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose is preferably about 10 to 1000 krad.

[0073] When the active energy ray is ultraviolet light, the paper-based substrate 11 does not easily transmit ultraviolet light, so it is preferable to irradiate it with ultraviolet light through the release sheet 13, which is a transparent plastic film.

[0074] The adhesive composition P may be applied to the release surface of the release sheet 13, and then the substrate 11 may be laminated onto the coated layer.

[0075] 3. Physical properties (1) Percentage of adhesive mass reduction In the adhesive sheet 1 (excluding the release sheet 13) according to this embodiment, when the mass per unit area of ​​the adhesive sheet 1 is M1 (mg), and the mass of the adhesive sheet 1 obtained by immersing a unit area of ​​the adhesive sheet 1 in a solvent for dissolving the adhesive layer 12 during recycling (methyl ethyl ketone is used in the test example) for 72 hours and then drying is M2 (mg), and when the mass per unit area of ​​the base material 11 is N1 (mg), and the mass of the base material 11 obtained by immersing the above unit area of ​​the base material 11 in a solvent for dissolving the adhesive layer 12 during recycling for 72 hours and then drying is N2 (mg), it is preferable that the adhesive mass reduction rate (%) calculated by the following formula (II) is 80% or more. The specific measurement method is as shown in the test example described later. Adhesive mass reduction rate (%)={1-(N1-N2) / (M1-M2)}×100...(II)

[0076] The above-mentioned adhesive mass reduction rate means that a large amount of adhesive is dissolved in the solvent, resulting in excellent recyclability of the adhesive. From this viewpoint, the above-mentioned adhesive mass reduction rate is more preferably 85% or more, particularly preferably 90% or more, even more preferably 95% or more, and most preferably 99% or more. The upper limit of the adhesive mass reduction rate is 100%.

[0077] (2) Total light transmittance The total light transmittance of the adhesive sheet 1 (excluding the release sheet 13) according to this embodiment is preferably 50% or less, more preferably 45% or less, particularly preferably 41% or less, and even more preferably 37% or less. This results in excellent opacity, making it suitable for use in labels and the like where opacity is required. The lower limit of the total light transmittance may be 0%, but is usually preferably 1% or more, more preferably 5% or more, particularly preferably 10% or more, even more preferably 20% or more, and most preferably 28% or more.

[0078] (3) Holding power The adhesive sheet 1 according to this embodiment has a holding force in accordance with JIS Z0237:2009, and when the adhesion area to the soda-lime glass is 25 mm x 25 mm, the test temperature is 23°C, the standing time is 24 hours, and the displacement amount measured with a load of 40 g is 20 mm or less, more preferably 18 mm or less, particularly preferably 15 mm or less, even more preferably 10 mm or less, among which preferably 5 mm or less, and most preferably 1 mm or less. This allows the adhesive sheet 1 to exhibit better fixing properties to the adherend, and better adhesion properties can be exhibited even when the adherend has a shape that is not flat, such as a curved surface. The lower limit of the displacement amount is 0 mm. Furthermore, the specific method for measuring the above holding force is as shown in the test example described later.

[0079] (4) Adhesive strength The adhesive strength of the adhesive sheet 1 to soda-lime glass according to this embodiment is preferably 1 N / 25 mm or more, more preferably 3 N / 25 mm or more, particularly preferably 5 N / 25 mm or more, even more preferably 7 N / 25 mm or more, and most preferably 10 N / 25 mm or more. This allows the adhesive sheet 1 to exhibit better fixation to the adherend, and better adhesion even when the adherend has a non-flat shape, such as a curved surface. Furthermore, the adhesive strength is preferably 100 N / 25 mm or less, more preferably 75 N / 25 mm or less, particularly preferably 50 N / 25 mm or less, and even more preferably 40 N / 25 mm or less. This provides reworkability, allowing for peeling from the adherend and re-attachment to the adherend.

[0080] Herein, the adhesive strength referred to herein basically means the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2009. The measurement sample shall be 25 mm wide and 100 mm long, and the measurement sample shall be attached to the substrate, pressurized at 0.5 MPa and 50°C for 20 minutes, left for 24 hours under normal pressure, 23°C, and 50% RH conditions, and then measured at a peeling speed of 300 mm / min.

[0081] (5) Curved surface lamination properties The adhesive sheet 1 according to this embodiment has a size of 15 mm width and 50 mm length. The adhesive layer is applied by wrapping it around a curved object to be adhered to (for example, a glass screw bottle with a diameter of 35 mm), and after standing for 24 hours in an environment of 23°C and 50% RH, the lifting of the adhesive sheet 1 from the object is visually checked. Preferably, the lifting at the longitudinal end is less than 5 mm, particularly preferably 3 mm or less, and even more preferably 1 mm or less.

[0082] The adhesive sheet 1 according to this embodiment has a size of 15 mm width and 50 mm length. When the adhesive layer is wrapped around a curved substrate (for example, a glass screw bottle with a diameter of 35 mm) and left to stand for 24 hours in an environment of 23°C and 50% RH, it is preferable that there is virtually no peeling at either the longitudinal or transverse end, and it is particularly preferable that there is no peeling at either the longitudinal or transverse end. This ensures that the adhesive sheet 1 exhibits good fixing properties even to a curved substrate.

[0083] (6) Immersion solubility In this embodiment, the adhesive sheet 1 preferably detaches from the soda-lime glass plate (thickness: 1.1 mm) after the adhesive layer is attached and the plate is immersed in a solvent (such as methyl ethyl ketone) for 72 hours. Preferably, the detachment time is within 72 hours, and particularly within 24 hours. This allows the adhesive sheet 1 to be separated from the adherend in a short time, enabling efficient recycling. Furthermore, from the viewpoint of recyclability, it is preferable that substantially no adhesive layer 12 (adhesive) remains on the substrate of the adhesive sheet 1 after detachment.

[0084] 4.Applications The adhesive sheet according to this embodiment can be preferably used in recyclable applications. Such applications are not particularly limited, but include, for example, labels (paper labels), fixing tapes (such as gummed tape), process tapes (such as masking tape for temporary fixing), etc. Furthermore, the objects to which the labels are applied are not particularly limited, but include, for example, various containers such as glass bottles, PET bottles, and cans, and packaging materials such as wrapping paper and cardboard.

[0085] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0086] For example, the release sheet 13 in the adhesive sheet 1 may be omitted.

[0087] In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y." [Examples]

[0088] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0089] [Example 1] 1. Preparation of the adhesive composition coating solution n-butyl acrylate as an acrylic monomer (A), 6-acrylamido-γ-cyclodextrin (B1) as a cyclodextrin derivative (B), and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (C) were mixed in the molar ratios shown in Table 1 and thoroughly stirred to obtain an adhesive composition.

[0090] Note that the molar ratios shown in Table 1 are the molar ratios for each acrylic monomer (A) when the total amount of acrylic monomer (A) is set to 100 mol, while the molar ratios for cyclodextrin derivatives (B), photopolymerization initiators (C), other components, and crosslinking agents are the molar ratios relative to the total amount of acrylic monomer (A) (100 mol).

[0091] 2. Manufacturing of adhesive sheets The adhesive composition obtained in the above step 1 was applied onto one side of a high-quality paper (manufactured by Nippon Paper Industries Co., Ltd., product name "WM Seal 64 Print Side Outer Roll", thickness 70 μm) as a base material using a knife coater to form a coating layer. Subsequently, a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") obtained by subjecting one side of a polyethylene terephthalate film to a release treatment with a silicone-based release agent was laminated such that the release-treated surface of the release sheet contacted the coating layer.

[0092] Thereafter, through the release sheet, active energy rays (ultraviolet rays; UV) were irradiated under the following conditions to cure the coating layer and form an adhesive layer with a thickness of 20 μm. In this manner, an adhesive sheet having a structure of base material / adhesive layer (thickness: 20 μm) / release sheet was produced.

[0093] <Active energy ray irradiation conditions> ·Using a high-pressure mercury lamp ·Illuminance 200 mW / cm 2 , light quantity 2000 mJ / cm 2 ·The UV illuminance and light quantity meter used was "UVPF-A1" manufactured by Eye Graphics Co., Ltd.

[0094] Note that the thickness of the above adhesive layer is a value measured in accordance with JIS K7130 using a constant-pressure thickness measuring instrument (manufactured by Teclock Corporation, product name "PG-02") (the same applies hereinafter).

[0095] [Examples 2 to 3, Comparative Examples 1 to 3] An adhesive sheet was produced in the same manner as in Example 1, except that the type and blending amount of the acrylic monomer (A), the type and blending amount of the cyclodextrin derivative (B), the blending amount of the photopolymerization initiator (C), and the thickness of the adhesive layer were changed as shown in Table 1. In Comparative Example 1, 0.1 mol of "TETRAD C" manufactured by Mitsubishi Gas Chemical Company was blended as an epoxy-based crosslinking agent. In Comparative Example 2, 1 mol of "EtAdA" (EtAD) manufactured by Osaka Organic Chemical Industry Co., Ltd. was blended. <00,00368> Details of the abbreviations and the like described in Table 1 are as follows. [Acrylic monomer (A)] BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate EA: Ethyl acrylate AA: Acrylic acid MMA: Methyl methacrylate 4HBA: 4-hydroxybutyl acrylate A-TMPT: Trimethylolpropane triacrylate [Cyclodextrin derivative (B)] B1: 6-acrylamide-γ-cyclodextrin B2: 6-acrylamide-β-cyclodextrin

[0097] [Test Example 1] (Measurement of gel fraction) The adhesive sheets obtained in the examples and comparative examples were cut to a size of 80 mm x 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200). The mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass was denoted as M1.

[0098] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Afterward, the adhesive was removed and air-dried for 24 hours at 23°C and 50% relative humidity, followed by 12 hours of drying in an oven at 80°C. After drying, its mass was measured using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass was denoted as M2. The gel fraction (%) is expressed as (M2 / M1) × 100. The gel fraction of the adhesive was then derived. The results are shown in Table 2.

[0099] [Test Example 2] (Molecular weight measurement of sol) The ethyl acetate used in the measurement of the gel fraction in Test Example 1 was concentrated using an evaporator to obtain the sol. The sol was then diluted with tetrahydrofuran to a 0.5% by mass solution, and the weight-average molecular weight (Mw) was measured. The results are shown in Table 2.

[0100] The weight-average molecular weight (Mw) mentioned above is the weight-average molecular weight in polystyrene terms, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> • GPC measuring device: Tosoh Corporation, HLC-8020 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Guard Column HXL-H TSK gel GMHXL (x2) TSK gel G2000HXL • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0101] [Test Example 3] (Measurement of haze value) The adhesive compositions prepared in the examples and comparative examples were applied using a knife coater to the peeled surface of a heavy-peel release sheet (Lintec Corporation, product name "SP-PET752150"), which was obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent, to form a coating layer of the same thickness as in the examples and comparative examples.

[0102] Next, the coating layer on the heavy-peel release sheet obtained above and a light-peel release sheet (Lintec Corporation, product name "SP-PET381031"), which had one side of a polyethylene terephthalate film peeled off with a silicone-based release agent, were laminated together so that the peeled surface of the light-peel release sheet was in contact with the coating layer.

[0103] Subsequently, the coated layer was cured by irradiating it with active energy rays (ultraviolet light; UV) through a light-peel release sheet under the same conditions as in the examples and comparative examples, thereby forming an adhesive layer of the same thickness as in the examples and comparative examples.

[0104] A light-peel release sheet was peeled from the adhesive layer, the adhesive layer was bonded to the glass, and then a heavy-peel release sheet was peeled off to create a sample for measurement. After background measurements were performed on the glass, the haze value (%) of the adhesive layer of the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") in accordance with JIS K7136:2000. The results are shown in Table 2.

[0105] [Test Example 4] (Measurement of total light transmittance) For the measurement samples prepared in Test Example 3, background measurements were performed on glass, and then the total light transmittance (%) of the adhesive layer was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0106] On the other hand, for the substrates used in the examples and comparative examples (before lamination of the adhesive layer), the total light transmittance (%) of the substrate was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0107] Furthermore, the release sheets were peeled off from the adhesive sheets obtained in the examples and comparative examples, and the adhesive layer was bonded to glass to be used as a measurement sample. After background measurements were performed on the glass, the total light transmittance (%) of the adhesive sheet (substrate + adhesive layer) of the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0108] The change in total light transmittance (points) was calculated by subtracting the total light transmittance (%) of the substrate alone from the total light transmittance (%) of the adhesive sheet (substrate + adhesive layer) obtained above. The results are shown in Table 2.

[0109] [Test Example 5] (Measurement of Adhesion) The adhesive sheets obtained in the examples and comparative examples were cut to a width of 25 mm and a length of 100 mm. Under conditions of 23°C and 50% RH, the release sheet was peeled off the adhesive sheet, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The sheet was then pressurized at 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. After that, it was left for 24 hours under conditions of 23°C and 50% RH to be used as a sample. The adhesive strength (N / 25 mm) was then measured using a tensile testing machine (manufactured by Orientec Co., Ltd., product name "Tensilon") under conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Measurements other than those described herein were performed in accordance with JIS Z0237:2009. The results are shown in Table 2.

[0110] [Test Example 6] (Measurement of Holding Force) The holding force of the adhesive sheet was measured in accordance with JIS Z0237:2009, except for the procedure described below. The adhesive sheets obtained in the examples and comparative examples were cut to a width of 25 mm and a length of 125 mm. The release sheet was peeled off, and only the 25 mm x 25 mm portion of the adhesive layer exposed on the adhesive sheet was attached to the soda-lime glass, so that the rest of the sheet did not come into contact with the soda-lime glass (the non-attached portion of the adhesive sheet was attached so that it extended beyond the soda-lime glass). The soda-lime glass was then positioned vertically on the ground with the adhesive sheet hanging from it, and left at 23°C and 50% RH for 15 minutes. After that, a load of 40 g was applied and left at 23°C and 50% RH for 24 hours, and the amount of displacement (mm) of the adhesive sheet before and after the 24-hour period was measured. The results are shown in Table 2.

[0111] [Test Example 7] (Evaluation of Recyclability of Substrate) The base material (high-quality paper) used in the examples and comparative examples had a unit area of ​​25 cm². 2 The mass N1 (mg) was measured. Also, the unit area was 25 cm². 2The substrate was immersed in methyl ethyl ketone (23°C) for 72 hours, then dried in an oven, and the mass N2 (mg) of the dried substrate was measured. Based on the obtained N1 and N2, the value of (N1-N2) / N1 was calculated. From the results, the recyclability of the substrate was evaluated based on the following criteria. The results are shown in Table 2. 〇…The value of (N1-N2) / N1 was greater than or equal to 0 and less than or equal to 0.1. ×…The value of (N1-N2) / N1 was less than 0 or greater than 0.1.

[0112] [Test Example 8] (Measurement of adhesive mass reduction rate) The adhesive sheets (substrate + adhesive layer; release sheet removed) obtained in the examples and comparative examples have a unit area of ​​25 cm². 2 The mass M1 (mg) was measured. Also, the unit area was 25 cm². 2 The adhesive sheet (substrate + adhesive layer) was immersed in methyl ethyl ketone (23°C) for 72 hours, then dried in an oven, and the mass M2 (mg) of the dried adhesive sheet (substrate + adhesive layer) was measured. Based on the obtained M1 and M2, as well as N1 and N2 obtained in Test Example 7, the percentage of adhesive mass loss (%) was calculated using the following formula (II). The results are shown in Table 2. Adhesive mass reduction rate (%)={1-(N1-N2) / (M1-M2)}×100...(II)

[0113] [Test Example 9] (Evaluation of concealment) A soda-lime glass plate (thickness: 1.1 mm) was placed on paper printed with red, blue, and green stripes. The release sheet was peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was attached to the soda-lime glass plate. The visibility of the paper printed with red, blue, and green was then checked. In addition, the substrate (high-quality paper) used in the examples and comparative examples was placed on the soda-lime glass plate, and the visibility of the paper printed with red, blue, and green was visually checked. By comparing these, the opacity of the adhesive sheet was evaluated based on the following criteria. The results are shown in Table 2. ◎...There was no difference compared to using high-quality paper alone. ○...Compared to plain high-quality paper, the opacity was reduced, but the color boundaries remained ambiguous. ×...Compared to plain high-quality paper alone, the opacity was clearly reduced, and the color boundaries were clearly visible.

[0114] [Test Example 10] (Evaluation of adhesion to curved surfaces) The adhesive sheets obtained in the examples and comparative examples were cut to a width of 15 mm and a length of 50 mm. The release liner was peeled off the adhesive sheet, and the exposed adhesive layer was attached to a glass screw-top bottle (35 mm in diameter) by wrapping it around the bottle. The bottle was left standing for 24 hours at 23°C and 50% RH. After that, the lifting and peeling of the adhesive sheet from the substrate was visually checked, and the adhesion properties of the adhesive sheet to curved surfaces were evaluated based on the following criteria. The results are shown in Table 2. ◎...No lifting or peeling was observed at all. ○...The longitudinal end lifted by less than 5mm, but there was no peeling. ×...There was peeling.

[0115] [Test Example 11] (Evaluation of immersion solubility) The release sheets were peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was attached to a soda-lime glass plate (thickness: 1.1 mm) to be used as a sample. The obtained samples were immersed in methyl ethyl ketone for 72 hours, and the time it took for the adhesive layer to dissolve and the adhesive sheet to detach from the soda-lime glass plate was confirmed. The immersion solubility of the adhesive layer was then evaluated based on the following criteria. The results are shown in Table 2. In Examples 1-3 and Comparative Example 2, no adhesive layer (adhesive) remained on the substrate of the adhesive sheet after detachment. ◎...Dropped out within 24 hours. 〇...They dropped out within 24 hours, but within 72 hours. ×...They did not drop out.

[0116] [Table 1]

[0117] [Table 2]

[0118] As can be seen from Table 2, the adhesive sheets of the examples exhibited excellent recyclability in both the base material and the adhesive layer. Furthermore, the adhesive sheets of the examples also exhibited excellent adhesion to curved surfaces and opacity. [Industrial applicability]

[0119] The adhesive sheet according to the present invention can be suitably used as a paper label that is intended for recycling. [Explanation of Symbols]

[0120] 1…Adhesive sheet 11...Base material 12…Adhesive layer 13…Release sheet

Claims

1. An adhesive sheet comprising a base material made of paper-based material and an adhesive layer laminated on at least one side of the base material, The adhesive constituting the adhesive layer contains a cyclodextrin derivative, The adhesive contains a polymer having a main chain obtained by copolymerizing an acrylic monomer with the cyclodextrin derivative having polymerizable groups. An adhesive sheet characterized by the following features.

2. The adhesive sheet according to claim 1, characterized in that the total light transmittance is 50% or less.

3. The adhesive sheet according to claim 1, characterized in that the gel fraction of the adhesive is 10% or less.

4. The adhesive sheet according to claim 1, characterized in that the change in total light transmittance (points) obtained by subtracting the total light transmittance (%) of the substrate alone from the total light transmittance (%) of the laminate comprising the substrate and the adhesive layer is 0 points or more and 20 points or less.

5. The mass of the substrate per unit area of ​​25 cm² when the thickness is 70 μm is N1 (mg), When the mass of the substrate obtained by immersing a substrate with a unit area of ​​25 cm² in methyl ethyl ketone for 72 hours and then drying it is N2 (mg), The adhesive sheet according to claim 1, characterized in that it satisfies the following relation (I). 0≦(N1-N2) / N1≦0.1...(I)

6. The adhesive sheet according to claim 1, characterized in that the holding force in accordance with JIS Z0237:2009 is 20 mm or less when the adhesion area to soda-lime glass is 25 mm x 25 mm, the test temperature is 23°C, the standing time is 24 hours, and the displacement amount measured by applying a load of 40 g is 20 mm or less.

7. The adhesive sheet according to claim 1, characterized in that its adhesive strength to soda-lime glass is 1 N / 25 mm or more.

8. The adhesive sheet according to claim 1, characterized in that the polymerizable group of the cyclodextrin derivative is a group containing a polymerizable unsaturated double bond.

9. The adhesive sheet according to any one of claims 1 to 8, characterized in that the weight-average molecular weight of the sol portion of the adhesive, determined by gel permeation chromatography, is 50,000 or more and 1,400,000 or less.

10. A coating film is formed by applying an adhesive composition containing an acrylic monomer and a cyclodextrin derivative having a polymerizable group to at least one side of a substrate made of paper-based material. The coating film is irradiated with active energy rays to copolymerize the acrylic monomer and the cyclodextrin derivative, thereby forming an adhesive layer. A method for manufacturing an adhesive sheet, characterized by the following:

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