Adhesive sheet and method for manufacturing the same

Abstract

Provided is an adhesive sheet 1 comprising at least an adhesive agent layer 11, wherein the gel fraction of an adhesive agent that makes up the adhesive agent layer 11 is less than 10%, and the 500% modulus of the adhesive agent layer 11 when subjected to a tensile test at 23°C is 0.02N / mm2 to 5N / mm2. Also provided is an adhesive sheet 1 wherein an adhesive agent that makes up an adhesive agent layer 11 includes a polymer having a main chain in which an acrylic monomer and a cyclodextrin derivative having a polymerizable group have been copolymerized. In the adhesive sheet 1, the adhesive agent layer 11 is recyclable.

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet and a method for manufacturing a pressure-sensitive adhesive sheet, and more particularly to a recyclable pressure-sensitive adhesive sheet and a method for manufacturing a pressure-sensitive adhesive sheet. [Background technology]

[0002] In recent years, there has been an increasing demand for the creation of a recycling-based society, and there is a growing demand for recyclability of various products and materials.

[0003] Recently, novel materials using cyclodextrin monomers have been proposed. Specifically, Patent Document 1 proposes a polymer material containing a crosslinked polymer crosslinked by the interaction between a host group and a guest group, in which the host group is a monovalent group obtained by removing one hydrogen atom or one hydroxyl group from cyclodextrin, and the crosslinked polymer contains 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, in which 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 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above-mentioned background, it is desirable that the adhesive layer of the adhesive sheet can also be recycled. However, Patent Documents 1 and 2 do not describe the adhesive of the adhesive sheet, nor do they mention recyclability at all.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive sheet that allows the pressure-sensitive adhesive layer to be recycled, and a method for producing the same. [Means for solving the problem]

[0008] In order to achieve the above object, firstly, the present invention provides a pressure-sensitive adhesive sheet including at least a pressure-sensitive adhesive layer, wherein the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is less than 10%, and the 500% modulus of the pressure-sensitive adhesive layer when subjected to a tensile test at 23°C is 0.02 N / mm 2 More than 5N / mm 2 The present invention provides a pressure-sensitive adhesive sheet characterized by the following (Invention 1).

[0009] In the above invention (Invention 1), the pressure-sensitive adhesive layer having the above physical properties has excellent recyclability. Specifically, it has excellent recoverability after dissolving in a solvent or the like, and the pressure-sensitive adhesive layer can be reformed from the pressure-sensitive adhesive solution obtained by dissolving in a solvent or the like. The reformed pressure-sensitive adhesive layer can exhibit adhesive strength close to that of the original pressure-sensitive adhesive layer.

[0010] In the above invention (Invention 1), when the adhesive strength of the adhesive layer to soda-lime glass is P1 (N / 25 mm) and the adhesive strength of the reformed adhesive layer formed from the adhesive solution obtained by dissolving the adhesive layer to soda-lime glass is P2 (N / 25 mm), it is preferable that the adhesive strength ratio of P2 to P1 (P2 / P1) is 0.5 or more and less than 1.47 (Invention 2).

[0011] In the above inventions (Inventions 1 and 2), when the mass per unit volume of the adhesive layer is defined as M1 (mg), and the adhesive solution obtained by dissolving the unit volume of the adhesive layer is filtered through a Tetron mesh #200 and the mass of the adhesive after drying is defined as M2 (mg), it is preferable that the mass ratio of M2 to M1 (M2 / M1) is 0.7 or more (Invention 3).

[0012] Secondly, the present invention provides an adhesive sheet having at least an adhesive layer, characterized in that the adhesive constituting the adhesive layer contains a polymer having a main chain obtained by copolymerizing an acrylic monomer and a cyclodextrin derivative having a polymerizable group (Invention 4).

[0013] The adhesive and adhesive layer of the adhesive sheet in the above invention (Invention 4) are likely to satisfy the aforementioned physical properties of gel fraction and 500% modulus, and therefore have excellent recyclability as described above. However, as long as the desired recyclability is obtained, it is not necessarily necessary to satisfy the aforementioned physical properties of gel fraction and 500% modulus.

[0014] In the above invention (Invention 4), the polymerizable group possessed by the cyclodextrin derivative is preferably a group containing a polymerizable unsaturated double bond (Invention 5).

[0015] In the above inventions (Inventions 4 and 5), it is preferable that the pressure-sensitive adhesive does not contain a guest molecule that can be included in the cyclodextrin derivative (Invention 6).

[0016] In the above inventions (Inventions 4 to 6), the weight average molecular weight of the sol portion of the pressure-sensitive adhesive, as determined by gel permeation chromatography, is preferably 100,000 or more and 3,000,000 or less (Invention 7).

[0017] In the above inventions (Inventions 4 to 7), the glass transition temperature (Tg) (measured value) of the polymer is preferably higher than −55° C. and 20° C. or lower (Invention 8).

[0018] In the above inventions (Inventions 1 to 8), it is preferable that the pressure-sensitive adhesive sheet has two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 9).

[0019] Thirdly, the present invention provides a method for producing an adhesive sheet having at least an adhesive layer, which comprises applying an adhesive composition containing an acrylic monomer and a cyclodextrin derivative having a polymerizable group to form a coating film, and irradiating the coating film with active energy rays to copolymerize the acrylic monomer and the cyclodextrin derivative to form an adhesive layer (Invention 10). [Effects of the Invention]

[0020] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention is recyclable. Furthermore, according to the method for producing a pressure-sensitive adhesive sheet according to the present invention, a pressure-sensitive adhesive sheet whose pressure-sensitive adhesive layer is recyclable can be produced. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described. The pressure-sensitive adhesive sheet according to one embodiment of the present invention includes at least a pressure-sensitive adhesive layer. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably has a gel fraction of less than 10%, and the pressure-sensitive adhesive layer has a 500% modulus of 0.02 N / mm when subjected to a tensile test at 23°C. 2 More than 5N / mm 2 It is preferable that the gel fraction and 500% modulus are as follows: In this specification, the methods for measuring the gel fraction and 500% modulus are as shown in the test examples described later.

[0023] A pressure-sensitive adhesive layer having the above physical properties has excellent recyclability. For example, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment is dissolved in a solvent or the like, filtered through a predetermined filtration membrane (e.g., Tetron mesh #200), and dried, the mass of the pressure-sensitive adhesive does not decrease significantly from the initial mass of the pressure-sensitive adhesive, resulting in excellent recoverability. This effect is particularly easily achieved by the low gel fraction described above. Note that filtration through a filtration membrane is performed to remove large molecular weight agglomerates that are unsuitable for recycling. Furthermore, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment can be dissolved in a solvent or the like, and the pressure-sensitive adhesive layer can be reformed from the resulting pressure-sensitive adhesive solution. The reformed pressure-sensitive adhesive layer can then exhibit adhesive strength close to that of the initial pressure-sensitive adhesive layer. This effect is easily achieved by the relatively high 500% modulus within a predetermined range, despite the low gel fraction described above.

[0024] From the viewpoint of recyclability, the gel fraction of the pressure-sensitive adhesive is preferably less than 10%, more preferably 9% or less, particularly preferably 8% or less, and even more preferably 7% or less. On the other hand, the lower limit of the gel fraction is most preferably 0%, but in practice it is preferably 1% or more, more preferably 2% or more, particularly preferably 3% or more, and even more preferably 3.7% or more.

[0025] From the viewpoint of recyclability, the 500% modulus of the pressure-sensitive adhesive layer is 0.02 N / mm 2 It is preferable that the resistance is 0.03N / mm or more. 2 More preferably, it is 0.06 N / mm or more, and particularly 0.06 N / mm 2 It is preferable that the resistance is 0.08 N / mm or more, and more preferably 0.08 N / mm 2 The 500% modulus of the pressure-sensitive adhesive layer is preferably 5 N / mm or more. 2 It is preferable that the resistance is less than 2N / mm 2 More preferably, it is equal to or less than 1 N / mm 2 It is preferable that the resistance is 0.5 N / mm or less, and more preferably 0.5 N / mm 2 Preferably, it is 0.2N / mm or less.2 This makes it easier for the adhesive layer to stretch up to 500% or more, and also improves the initial adhesive strength and re-formed adhesive strength, which will be described later.

[0026] The recyclability related to the recoverability can be expressed in terms of physical properties. The mass per unit volume of the adhesive layer of the adhesive sheet according to this embodiment is defined as M1 (mg), and the mass of the adhesive after dissolving the adhesive layer in a solvent or the like to obtain an adhesive solution and filtering the solution through a Tetron mesh #200 and drying is defined as M2 (mg). The mass ratio of M2 to M1 (M2 / M1) is preferably 0.7 or greater, more preferably 0.8 or greater, and even more preferably 0.9 or greater. The upper limit of the mass ratio (M2 / M1) is most preferably 1, but in practice it is preferably 0.99 or less, more preferably 0.98 or less, and even more preferably 0.97 or less. Specific methods for measuring each mass are as described in the test examples below.

[0027] Furthermore, when the recyclability of the adhesive strength is expressed in terms of physical properties, the adhesive strength of the adhesive layer of the adhesive sheet according to this embodiment to soda-lime glass is defined as P1 (N / 25 mm), and the adhesive strength of a reformed adhesive layer formed from an adhesive solution obtained by dissolving the adhesive layer in a solvent or the like is defined as P2 (N / 25 mm), the adhesive strength ratio of P2 to P1 (P2 / P1) is preferably 0.5 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, even more preferably 0.9 or more, and most preferably 0.95 or more. Furthermore, from the viewpoint of reworkability, the adhesive strength ratio (P2 / P1) is preferably less than 1.47, more preferably 1.4 or less, particularly preferably 1.2 or less, even more preferably 1.1 or less, and most preferably 1.0 or less.

[0028] Here, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2009, and the measurement sample is 25 mm wide and 100 mm long, and the measurement sample is attached to the adherend and pressurized at 0.5 MPa and 50°C for 20 minutes, and then left to stand for 24 hours under conditions of normal pressure, 23°C, and 50% RH, and then measured at a peel speed of 300 mm / min.

[0029] Another embodiment of the pressure-sensitive adhesive sheet of the present invention includes at least a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably contains a polymer having a main chain formed by copolymerizing an acrylic monomer and a cyclodextrin derivative having a polymerizable group. The pressure-sensitive adhesive and pressure-sensitive adhesive layer of such a pressure-sensitive adhesive sheet are likely to satisfy the aforementioned physical properties of gel fraction and 500% modulus, and therefore have excellent recyclability as described above. The pressure-sensitive adhesive preferably satisfies the aforementioned gel fraction.

[0030] The pressure-sensitive adhesive preferably does not contain a guest molecule that can be included in the cyclodextrin derivative. In this specification, "inclusion" refers to the phenomenon in which a guest molecule is incorporated into the cavity of a host molecule (cyclodextrin derivative). In this specification, "guest molecule" refers to a molecule that can be included in a cyclodextrin derivative, including those that have not yet been included. Examples of such guest molecules include n-butyl acrylate, styrene, octyl acrylate, and dodecyl acrylate for α-cyclodextrin derivatives, n-butyl acrylate, t-butyl acrylate, styrene, adamantyl acrylate, and isobornyl acrylate for β-cyclodextrin derivatives, and octyl acrylate and dodecyl acrylate for γ-cyclodextrin derivatives.

[0031] In this specification, the phrase "the PSA does not contain guest molecules that can be included in a cyclodextrin derivative" means that the PSA does not substantially contain any guest molecules. Specifically, the PSA is allowed to 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 monomers. For example, the monomers listed above may be used as acrylic monomers. These monomers basically become polymers by polymerization and do not become guest molecules that can be included in a cyclodextrin derivative. However, they may remain in small amounts after polymerization, and are therefore defined as above.

[0032] The polymer having a main chain obtained by copolymerizing the above-mentioned acrylic monomer with a cyclodextrin derivative having a polymerizable group preferably does not have a branched structure, which makes it possible to prevent the resulting PSA from becoming too dense and to easily satisfy the above-mentioned physical properties.

[0033] The pressure-sensitive adhesive layer is preferably formed from a pressure-sensitive adhesive composition (hereinafter sometimes referred to as "pressure-sensitive adhesive composition P") containing an acrylic monomer (A), a cyclodextrin derivative (B) having a polymerizable group, and preferably further a photopolymerization initiator (C). Note that a polymer having a main chain obtained by copolymerizing the acrylic monomer (A) and the cyclodextrin derivative (B) is hereinafter sometimes referred to as "polymer Q."

[0034] 1. Each ingredient (1) Acrylic Monomer (A) The acrylic monomer (A) in this embodiment is preferably a monofunctional acrylic monomer, which allows the polymer Q of the acrylic monomer (A) and the cyclodextrin derivative (B) to have no branched structure, making it easier to satisfy the above-mentioned physical properties.

[0035] Preferred examples of the acrylic monomer (A) in this embodiment include (meth)acrylic acid esters, (meth)acrylic acid, (meth)acrylamide, vinyl acetate, and styrene. The acrylic monomer (A) may be used alone 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.

[0036] Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters in which the alkyl group is linear or branched, (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.

[0037] From the viewpoint of adhesiveness, the (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group with a carbon number of 1 to 20. Examples of (meth)acrylic acid alkyl esters having an alkyl group with a carbon number of 1 to 20 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 achieving good adhesiveness, (meth)acrylic acid esters having an alkyl group carbon number of 1 to 8 are preferred, with methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. being more preferred, and from the viewpoint of recyclability, methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. are particularly preferred. Furthermore, from the viewpoint of making it easier for the resulting adhesive layer to satisfy the physical properties such as the 500% modulus and adhesive strength ratio described above, ethyl acrylate, n-butyl acrylate, etc. are preferred.

[0038] Because (meth)acrylic acid esters having a cyclic structure are bulky, it is presumed that their presence in the polymer appropriately widens the spacing between polymer molecules. As a result, the resulting adhesive has excellent flexibility while maintaining cohesiveness, making it easier to achieve the physical properties such as the 500% modulus and adhesive strength ratio described above. From this perspective, among (meth)acrylic acid esters having a cyclic structure, (meth)acrylic acid esters having an alicyclic structure are particularly preferred, and examples thereof include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among these, isobornyl (meth)acrylate is preferred, and isobornyl acrylate is particularly preferred, from the viewpoint that the resulting adhesive layer easily achieves the above-mentioned physical properties.

[0039] Examples of (meth)acrylic acid esters having a functional group such as a hydroxyl group include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, from the viewpoint that the resulting pressure-sensitive adhesive layer easily satisfies the above-mentioned physical properties, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like are preferred, and 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and the like are particularly preferred.

[0040] Among the above, from the viewpoint of adhesiveness, it is preferable to use a (meth)acrylic acid ester having at least 1 to 8 carbon atoms in the alkyl group. When the total amount of acrylic monomer (A) is taken as 100 mol, the blending amount of the (meth)acrylic acid ester having 1 to 8 carbon atoms in the alkyl group is preferably 30 to 100 mol, and when a (meth)acrylic acid ester having a functional group such as a hydroxyl group is used in combination as the acrylic monomer (A), it is more preferably 50 to 99 mol, particularly preferably 60 to 97 mol, even more preferably 80 to 95 mol, and most preferably 90 to 94 mol. This makes it easier for the resulting adhesive layer to satisfy the above-mentioned physical properties and to exhibit good recyclability.

[0041] When the above-mentioned (meth)acrylic acid ester having a cyclic structure is used as the acrylic monomer (A), it is preferably used in combination with at least the above-mentioned (meth)acrylic acid ester having an alkyl group with 1 to 8 carbon atoms. In this case, when the total amount of the acrylic monomer (A) is taken as 100 mol, the blending amount of the above-mentioned (meth)acrylic acid ester having a cyclic structure is preferably 1 to 30 mol, more preferably 2 to 20 mol, particularly preferably 3 to 10 mol, and even more preferably 4 to 5 mol. This makes it easier for the resulting pressure-sensitive adhesive layer to satisfy the above-mentioned physical properties and to exhibit good recyclability.

[0042] When the above-mentioned (meth)acrylic acid ester having a functional group such as a hydroxyl group is used as the acrylic monomer (A), it is preferably used in combination with at least the above-mentioned (meth)acrylic acid ester having an alkyl group with 1 to 8 carbon atoms. In this case, when the total amount of the acrylic monomer (A) is taken as 100 mol, the amount of the above-mentioned (meth)acrylic acid ester having a functional group such as a hydroxyl group is preferably 0.1 to 10 mol, more preferably 0.2 to 5 mol, particularly preferably 0.4 to 2 mol, and even more preferably 0.6 to 1 mol. This makes it easier for the resulting pressure-sensitive adhesive layer to satisfy the above-mentioned physical properties and to exhibit good recyclability.

[0043] When (meth)acrylic acid is used as the acrylic monomer (A), it is preferably used in combination with at least the above-mentioned (meth)acrylic acid ester having an alkyl group carbon number of 1 to 8. In this case, when the total amount of the acrylic monomer (A) is taken as 100 mol, the amount of the above-mentioned (meth)acrylic acid is preferably 0.1 to 20 mol, more preferably 1 to 18 mol, particularly preferably 5 to 14 mol, and even more preferably 8 to 12 mol. This makes it easier for the resulting pressure-sensitive adhesive layer to satisfy the above-mentioned physical properties and to exhibit good recyclability.

[0044] (2) Cyclodextrin derivative (B) In this embodiment, the cyclodextrin portion of the cyclodextrin derivative (B) having a polymerizable group is preferably α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin, and from the viewpoint of solvent solubility, β-cyclodextrin or γ-cyclodextrin is particularly preferred.

[0045] 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). However, it is preferably a group containing a polymerizable unsaturated double bond, more preferably an ethylenically unsaturated group, and more preferably a (meth)acryloyl group, a vinyl group, an allyl group, or the like, and particularly preferably a (meth)acryloyl group.

[0046] Preferably, the cyclodextrin derivative (B) has one polymerizable group per cyclodextrin molecule, which allows the polymer Q of the acrylic monomer (A) and the cyclodextrin derivative (B) to have no branched structure, making it easier to achieve the above-mentioned physical properties.

[0047] From the above viewpoint, it is preferable that the content of the cyclodextrin derivative having two or more polymerizable groups per molecule in the pressure-sensitive adhesive composition P is small. Specifically, it is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less.

[0048] The cyclodextrin derivative (B) in this embodiment is preferably a compound represented by the following formula (1). [ka] (R in the above formula (1) 1 represents a hydrogen atom or a methyl group. 2 represents O, NH, or a hydrocarbon containing NH. CD represents α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin.

[0049] 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-, -CH2-O-CO-NH-C2H4-O-, etc.

[0050] The content of the cyclodextrin derivative (B) in the pressure-sensitive adhesive composition P is preferably a molar ratio of 0.01 or more, more preferably 0.1 or more, particularly preferably 0.5 or more, and even more preferably 0.8 or more, when the total amount of the acrylic monomer (A) is taken as 100 mol. When the upper limit of the cyclodextrin derivative (B) content is within the above range, the above-mentioned physical properties are more likely to be satisfied and good adhesiveness is obtained. In particular, when the cyclodextrin moiety of the cyclodextrin derivative (B) is γ-cyclodextrin, the above molar ratio is preferably 1.2 or more, particularly preferably 1.5 or more, and even more preferably 1.8 or more, from the viewpoint that the 500% modulus of the obtained pressure-sensitive adhesive layer more likely to satisfy the above-mentioned value.

[0051] Furthermore, the content of the cyclodextrin derivative (B), expressed as a molar ratio when the total amount of the acrylic monomer (A) is taken as 100 mol, is preferably 10 or less, more preferably 7 or less, particularly preferably 4 or less, and even more preferably 2 or less. When the content of the cyclodextrin derivative (B) is within the above range, the above-mentioned physical properties are more likely to be satisfied and good adhesiveness is obtained. In particular, when the cyclodextrin moiety of the cyclodextrin derivative (B) is β-cyclodextrin, the above molar ratio is preferably 1.8 or less, particularly preferably 1.5 or less, and even more preferably 1.2 or less, from the viewpoint that the 500% modulus of the obtained adhesive layer more likely to satisfy the above-mentioned value.

[0052] When the total amount of the acrylic monomer (A) is taken as 100 mol, the molar ratio of the cyclodextrin derivative (B) is N, and the thickness of the pressure-sensitive adhesive layer is Z (μm), the value N×Z obtained by multiplying these is preferably 22 to 1000, more preferably 25 to 500, particularly preferably 28 to 100, and even more preferably 30 to 60. This makes it easier for the 500% modulus of the resulting pressure-sensitive adhesive layer to satisfy the aforementioned value, and also makes it easier for the desired adhesive strength to be exerted.

[0053] (3) Photopolymerization initiator (C) When ultraviolet light is used as the active energy ray for copolymerizing the acrylic monomer (A) and the cyclodextrin derivative (B) having a polymerizable group, the pressure-sensitive adhesive composition P preferably further contains a photopolymerization initiator (C). By containing the photopolymerization initiator (C), the acrylic monomer (A) can be efficiently copolymerized without remaining in the pressure-sensitive adhesive, and the polymerization and curing time and the exposure dose of the active energy ray can be reduced.

[0054] 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-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, Examples of the benzophenone 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, benzyl dimethyl 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 alone or in combination of two or more.

[0055] The content of the photopolymerization initiator (C) in the pressure-sensitive adhesive composition P, expressed as a molar ratio of 100 mol of the total amount of the acrylic monomer (A) and the cyclodextrin derivative (B), is preferably 0.001 to 10, more preferably 0.01 to 1, and even more preferably 0.02 to 0.5, particularly preferably 0.05 to 0.3, and even more preferably 0.1 to 0.2. This makes it easier for the resulting pressure-sensitive adhesive layer to satisfy the above-mentioned physical properties and exhibit good recyclability.

[0056] (4) Various additives If desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as a silane coupling agent, an anti-rust agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a refractive index adjuster, and a filler, can be added to the pressure-sensitive adhesive composition P.

[0057] 2. Physical Properties (1) Weight-average molecular weight of sol component The weight-average molecular weight of the sol fraction of the pressure-sensitive adhesive, as determined by gel permeation chromatography, is preferably 100,000 or more and 3,000,000 or less. This makes it easier for the physical properties described above to be satisfied, resulting in a pressure-sensitive adhesive layer that exhibits good recyclability. From this perspective, the weight-average molecular weight of the sol fraction is more preferably 300,000 to 2,400,000, particularly preferably 600,000 to 1,800,000, even more preferably 700,000 to 1,600,000, and most preferably 800,000 to 1,400,000. The specific method for measuring the weight-average molecular weight of the sol fraction is as shown in the test examples described below.

[0058] (2) Glass transition temperature (Tg) The measured glass transition temperature (Tg) of the polymer Q is preferably greater than -55°C and equal to or less than 20°C. This makes it easier for the physical properties described above to be satisfied, resulting in a pressure-sensitive adhesive layer that exhibits good recyclability. From this perspective, the glass transition temperature (Tg) of the polymer Q is more preferably -50°C to 10°C, more preferably -45°C to 0°C, particularly preferably -42°C to -5°C, and even more preferably -38°C to -10°C. The glass transition temperature (Tg) of the polymer is measured as shown in the test examples described below.

[0059] (3) Thickness of adhesive layer The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to this embodiment (measured in accordance with JIS K7130) is preferably 1 μm or more, more preferably 4 μm or more, particularly preferably 10 μm or more, even more preferably 18 μm or more, and most preferably 26 μm or more. This allows the desired adhesive strength to be exerted. The thickness of the pressure-sensitive adhesive layer is preferably 1000 μm or less, more preferably 600 μm or less, and especially preferably 300 μm or less. From the viewpoint of improving processability, handleability, economic efficiency, etc., the thickness is preferably 200 μm or less, more preferably 100 μm or less, particularly preferably 85 μm or less, even more preferably 55 μm or less, and most preferably 35 μm or less. The pressure-sensitive adhesive layer may be formed as a single layer or may be formed by laminating multiple layers.

[0060] (4) Adhesive strength The adhesive strength (initial adhesive strength) of the adhesive layer in the adhesive sheet according to this embodiment to soda-lime glass is preferably 0.1 N / 25 mm or more, more preferably 1 N / 25 mm or more, particularly preferably 4 N / 25 mm or more, even more preferably 8 N / 25 mm or more, and most preferably 12 N / 25 mm or more. This allows adherends to be closely attached and fixed to each other. Furthermore, the adhesive strength (initial 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 allows for reworkability, allowing the sheet to be peeled from and reattached to an adherend.

[0061] Furthermore, the adhesive strength (reformation adhesive strength) of the reformable adhesive layer formed from an adhesive solution obtained by dissolving the adhesive layer in the adhesive sheet according to this embodiment in a solvent or the like to soda-lime glass is preferably 0.1 N / 25 mm or more, more preferably 1 N / 25 mm or more, particularly preferably 4 N / 25 mm or more, even more preferably 8 N / 25 mm or more, and most preferably 12 N / 25 mm or more. This allows adherends to be reattached and fixed together again. Furthermore, the above adhesive strength (reformation 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 allows reworkability to be achieved again.

[0062] 3. Manufacturing method of adhesive sheet To produce the pressure-sensitive adhesive sheet according to this embodiment, first, a pressure-sensitive adhesive composition P is preferably prepared. Specifically, an acrylic monomer (A), a cyclodextrin derivative (B), and optionally a photopolymerization initiator (C), additives, etc. are mixed together. It is preferable that the pressure-sensitive adhesive composition P does not contain a solvent (water, organic solvent, etc.).

[0063] Next, the pressure-sensitive adhesive composition P is applied to a desired object to form a coating film. Examples of the desired object include a release sheet, which will be described later, as well as a desired substrate. The substrate can be appropriately selected depending on the application of the pressure-sensitive adhesive sheet. Examples of materials for the substrate include resin, glass, metal, ceramics, etc. The substrate may be in the form of a film, plate, block, etc. Examples of resins include polyesters such as polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; celluloses such as triacetyl cellulose; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymers, polyurethane, polystyrene, polyimide, polyether ether ketone, polyetherimide, polyethersulfone, polyphenylsulfone, polyphenylene sulfide, aramid, nylon, acrylic resins, norbornene-based resins, and cycloolefin resins.

[0064] The pressure-sensitive adhesive composition P can be applied by, for example, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, or the like.

[0065] After the coating film of the pressure-sensitive adhesive composition P is formed, the coating film is irradiated with active energy rays to copolymerize the acrylic monomer (A) and the cyclodextrin derivative (B) to form a pressure-sensitive adhesive layer. A release sheet may be laminated on the pressure-sensitive adhesive layer thus formed.

[0066] The active energy ray refers to an electromagnetic wave or a charged particle beam that has an energy quantum, and specific examples thereof include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0067] The ultraviolet irradiation can be performed using a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the amount of ultraviolet irradiation is set to an illuminance of 50 to 1000 mW / cm. 2It is preferable that the intensity is about 100 to 500 mW / cm 2 The light intensity is preferably about 50 to 10,000 mJ / cm. 2 is preferably 200 to 7000 mJ / cm 2 More preferably, it is 500 to 3000 mJ / cm 2 On the other hand, the electron beam irradiation can be carried out by an electron beam accelerator or the like, and the irradiation dose of the electron beam is preferably about 10 to 1000 krad.

[0068] 4. Adhesive sheet type The pressure-sensitive adhesive sheet according to the present embodiment is sufficient as long as it includes at least a pressure-sensitive adhesive layer, but it is preferable that a release sheet be laminated on at least one side of the pressure-sensitive adhesive layer, and it is also preferable that release sheets be laminated on both sides of the pressure-sensitive adhesive layer. Furthermore, the above-mentioned substrate may be laminated on one side of the pressure-sensitive adhesive layer.

[0069] A specific configuration of one example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in Figure 1. As shown in Figure 1, the pressure-sensitive adhesive sheet 1 according to one embodiment is composed of two release sheets 12a, 12b and a pressure-sensitive adhesive layer 11 sandwiched between the two release sheets 12a, 12b so as to be in contact with the release surfaces of the two release sheets 12a, 12b. In this specification, the release surface of a release sheet refers to the surface of the release sheet that has releasability, and includes both a surface that has been subjected to a release treatment and a surface that exhibits releasability even without being subjected to a release treatment.

[0070] The pressure-sensitive adhesive layer 11 is a pressure-sensitive adhesive layer as described above, and is preferably made of a pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition P with active energy rays.

[0071] Release sheets 12a and 12b protect adhesive layer 11 until adhesive sheet 1 is used, and are peeled off when adhesive sheet 1 (adhesive layer 11) is to be used. In adhesive sheet 1 according to this embodiment, one or both of release sheets 12a and 12b are not necessarily required.

[0072] Examples of materials that can be used as the release sheets 12a and 12b include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these materials can also be used. Furthermore, laminated films of these materials can also be used.

[0073] The release surfaces of the release sheets 12a and 12b (particularly the surfaces in contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Preferably, one of the release sheets 12a and 12b is a heavy-release type release sheet with a high release strength, and the other is a light-release type release sheet with a low release strength.

[0074] There are no particular restrictions on the thickness of the release sheets 12a and 12b, but it is usually about 20 to 200 μm.

[0075] In one example of manufacturing the pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a (or 12b) to form a coating layer, and then the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. Next, active energy rays are irradiated onto the coating layer of the pressure-sensitive adhesive composition P through one of the release sheets to cure the coating layer and form a pressure-sensitive adhesive layer. This gives the pressure-sensitive adhesive sheet 1.

[0076] 5.Applications The pressure-sensitive adhesive sheet according to the present embodiment can be preferably used in applications in fields where recycling is possible. Such applications are not particularly limited, but include, for example, laminating components together in various devices and products such as displays, solar panels, semiconductor devices, batteries, mobile objects (automobiles, railway vehicles, ships, aircraft, etc.), glass shatter prevention materials, wall decoration, label attachment, workpiece processing applications in which the sheet is temporarily attached to a workpiece such as a semiconductor or glass in order to process the workpiece, protection applications in which a protective sheet is attached to temporarily or continuously protect various components and products, workpiece transport applications, and foreign matter removal applications.

[0077] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, 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.

[0078] For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted.

[0079] In this specification, when it is written "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also includes the meaning "preferably greater than X" or "preferably smaller than Y." Furthermore, when it is written "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is written "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified. [Example]

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

[0081] Example 1 1. Preparation of adhesive composition coating solution n-Butyl acrylate and ethyl acrylate as acrylic monomers (A), 6-acrylamide-β-cyclodextrin (B1) as cyclodextrin derivative (B), and 1-hydroxycyclohexyl phenyl ketone as photopolymerization initiator (C) were mixed in the molar ratios shown in Table 1 and thoroughly stirred to obtain a pressure-sensitive adhesive composition.

[0082] The molar ratios shown in Table 1 are, for each acrylic monomer (A), the molar ratio when the total amount of the acrylic monomer (A) is 100 mol; for the cyclodextrin derivative (B), the molar ratio is relative to the total amount of the acrylic monomer (A), 100 mol; and for the photopolymerization initiator (C), the molar ratio is relative to the total amount of the acrylic monomer (A) and the cyclodextrin derivative (B), 100 mol.

[0083] 2. Manufacturing of adhesive sheets The pressure-sensitive adhesive composition obtained in step 1 above was applied using a knife coater to the release-treated surface of a heavy-release release sheet (manufactured by Lintec Corporation, product name "SP-PET752150"), one side of which had been treated with a silicone-based release agent to form a coating layer.

[0084] Next, the coating layer on the heavy release type release sheet obtained above was attached to a light release type release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") in which one side of a polyethylene terephthalate film had been treated with a silicone-based release agent, so that the release-treated side of the light release type release sheet was in contact with the coating layer.

[0085] The coating layer was then cured by irradiating it with active energy rays (ultraviolet rays; UV) through the light release release sheet under the following conditions to form a 30 μm thick adhesive layer. In this way, an adhesive sheet consisting of a heavy release release sheet / adhesive layer (thickness: 30 μm) / light release release sheet was produced.

[0086] <Activated energy ray irradiation conditions> -High pressure mercury lamp used ·Illuminance 200mW / cm 2 ,Light intensity 2000mJ / cm 2 The UV illuminance and light intensity meter used is the "UVPF-A1" manufactured by Eye Graphics.

[0087] The thickness of the pressure-sensitive 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).

[0088] [Examples 2 to 4, Comparative Examples 1 to 3] An adhesive sheet was produced in the same manner as in Example 1, except that the type and amount of acrylic monomer (A), the type and amount of cyclodextrin derivative (B), the amount of photopolymerization initiator (C), and the thickness of the adhesive layer were changed as shown in Table 1.

[0089] Details of the abbreviations and other information listed in Table 1 are as follows: [Acrylic Monomer (A)] BA: n-butyl acrylate EA: Ethyl acrylate AA: acrylic acid MMA: methyl methacrylate IBXA: Isobornyl acrylate 4HBA: 4-hydroxybutyl acrylate DCP: Dicyclopentadiene (for convenience, listed in the acrylic monomer (A) column) [Cyclodextrin derivative (B)] B1: 6-acrylamido-β-cyclodextrin B2: 6-acrylamido-γ-cyclodextrin B3: Di(2-isocyanateethyl acrylate)-β-cyclodextrin

[0090] Here, N×Z was calculated, where N is the number of moles of the cyclodextrin derivative (B) used in the Examples and Comparative Examples, and Z (μm) is the thickness of the adhesive layer. The results are shown in Table 1.

[0091] [Test Example 1] (Measurement of gel fraction) The pressure-sensitive adhesive sheets obtained in the examples and comparative examples were cut to a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed on a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the pressure-sensitive adhesive alone. This mass was designated M1.

[0092] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. The adhesive was then removed and air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and then dried in an oven at 80°C for 12 hours. After drying, 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 designated M2. The gel fraction (%) was expressed as (M2 / M1) x 100. The gel fraction of the adhesive was calculated from this. The results are shown in Table 2.

[0093] [Test Example 2] (Measurement of molecular weight of sol content) The ethyl acetate used in measuring the gel fraction in Test Example 1 was concentrated with an evaporator to obtain a sol fraction. The sol fraction 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.

[0094] The weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> GPC measuring device: Tosoh HLC-8020 GPC columns (passed in the following order): Tosoh Corporation TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0095] Test Example 3 (Measurement of Glass Transition Temperature (Tg)) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets prepared in the Examples and Comparative Examples were stacked together to form a laminate with a thickness of 0.8 mm. A cylindrical body with a diameter of 8 mm (height of 0.8 mm) was punched out from the resulting pressure-sensitive adhesive layer laminate, and this was used as a sample.

[0096] The loss tangents of the above samples were measured using a dynamic viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR 301") under the following conditions using the torsional shear method in accordance with JIS K7244-1. The glass transition temperatures (Tg) of the pressure-sensitive adhesives (polymers) prepared in the examples and comparative examples were calculated from the maximum values ​​of the loss tangents. The results are shown in Table 2. Measurement frequency: 1Hz Measurement temperature range: -60℃~80℃ Heating rate: 5℃ / min

[0097] Test Example 4 (Measurement of 500% modulus) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples were laminated in multiple layers to a total thickness of 600 μm, and then a sample measuring 10 mm wide x 75 mm long was cut out. The sample was set in a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon") so that the sample measurement area was 10 mm wide x 20 mm long (in the extension direction), and elongated using the tensile tester at a tensile speed of 200 mm / min in an environment of 23°C and 50% RH. The stress value at which the elongation rate reached 500% was determined as the 500% modulus (N / mm 2 The results are shown in Table 2. Note that the sample for Comparative Example 3 broke during the measurement.

[0098] [Test Example 5] (Measurement of adhesive strength) The light-release release sheets were peeled off from the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET50 A4360", thickness: 50 μm) having an easy-adhesion layer, to obtain a heavy-release release sheet / pressure-sensitive adhesive layer / PET film laminate. The resulting laminate was cut into a width of 25 mm and a length of 100 mm.

[0099] The heavy-release release sheet was peeled from the laminate under an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The laminate was then pressurized in an autoclave manufactured by Kurihara Manufacturing Co., Ltd. at 0.5 MPa and 50°C for 20 minutes. The laminate was then left to stand for 24 hours under conditions of 23°C and 50% RH, and this was used as a sample. The adhesive strength (initial adhesive strength (P1); N / 25 mm) was measured using a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon") at a peel rate of 300 mm / min and a peel angle of 180°. Measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2009. The results are shown in Table 2.

[0100] Next, the adhesive layer of the adhesive sheet obtained in each of the Examples and Comparative Examples was dissolved in ethyl acetate to adjust the solids concentration to 30% by mass. The resulting adhesive solution was filtered through a Tetron mesh #200. The filtrate was then applied with a knife coater to the release-treated surface of a heavy release type release sheet similar to the heavy release type release sheet described above, and then heated at 90°C for 1 minute to form a reformed adhesive layer.

[0101] Next, the reformable adhesive layer on the heavy release release sheet obtained above was attached to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET50 A4360", thickness: 50 μm) having an easy-adhesion layer, to obtain a laminate of heavy release release sheet / reformable adhesive layer / PET film. Using this laminate, the adhesive strength of the reformable adhesive layer (reformable adhesive strength (P2); N / 25 mm) was measured in the same manner as above. The results are shown in Table 2.

[0102] Based on the above measurement results, the adhesive strength ratio (P2 / P1) of the reformed adhesive strength (P2) to the initial adhesive strength (P1) was calculated. The results are shown in Table 2.

[0103] [Test Example 6] (Evaluation of reworkability) In measuring the initial adhesive strength in Test Example 5, the presence or absence of adhesive residue (so-called adhesive residue) on the soda-lime glass was visually confirmed when the laminate of the PET film and the adhesive layer was peeled off from the soda-lime glass, and the reworkability was evaluated based on the following criteria. The results are shown in Table 2. ⊚: No adhesive remained at all. ◯: Some adhesive remained. ×: Adhesive remained over the entire surface.

[0104] [Test Example 7] (Evaluation of reshaping ability) In Test Example 5, whether or not the above-mentioned reformable pressure-sensitive adhesive layer was successfully formed was judged visually, and the reformability was evaluated based on the following criteria. The results are shown in Table 2. ◯: A reformable adhesive layer was successfully formed. ×: A reformable adhesive layer could not be formed satisfactorily. In addition, in Comparative Examples 1 and 3, where the re-formability of the adhesive layer was determined to be poor, the re-formation adhesive strength of Test Example 5 could not be measured.

[0105] [Test Example 8] (Derivation of adhesive mass ratio) 50 mm of the adhesive layer of the adhesive sheets obtained in the Examples and Comparative Examples 3 The mass (initial adhesive mass (M1); mg) of the adhesive was measured. 3 A portion of the adhesive layer was dissolved in ethyl acetate, and the resulting adhesive solution was filtered through a Tetron mesh #200. The filtrate was then completely dried. The mass of the adhesive recovered in this manner (recovered adhesive mass (M2); mg) was measured. Based on the above measurement results, the mass ratio (M2 / M1) of the recovered adhesive mass (M2) to the initial adhesive mass (M1) was calculated. The results are shown in Table 2. If this mass ratio (M2 / M1) is 0.7 or higher, it can be said that the adhesive recovery is excellent.

[0106] Test Example 9 (Evaluation of Immersion Solubility) The light-release release sheet was peeled off from the pressure-sensitive adhesive sheets obtained in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET50 A4360", thickness: 50 μm) having an easy-adhesion layer, and then the heavy-release release sheet was peeled off. The obtained pressure-sensitive adhesive layer / PET film laminate was cut into a size of 25 mm × 100 mm, and this was used as a sample.

[0107] The obtained sample was immersed in ethyl acetate for 72 hours, then removed, and the presence or absence of the adhesive on the surface of the PET film of the sample facing the adhesive layer was checked with a finger and visually. The immersion solubility of the adhesive layer was then evaluated according to the following criteria. The results are shown in Table 2. ◎...It wasn't sticky. ◯: Sticky, but no adhesive residue was visible. ×: Remaining adhesive was visually observed.

[0108] [Table 1]

[0109] [Table 2]

[0110] As can be seen from Table 2, the adhesive layer of the adhesive sheet produced in the Examples exhibited high recoverability, and the adhesive strength of the reformed adhesive layer was close to that of the initial adhesive layer, so that it had excellent recyclability. Furthermore, the adhesive layer of the adhesive sheet produced in the Examples exhibited good reworkability and immersion solubility, so that it also had excellent recyclability from these perspectives. [Industrial Applicability]

[0111] The pressure-sensitive adhesive sheet according to the present invention can be suitably used in products for which recycling is desired. [Explanation of symbols]

[0112] 1...Adhesive sheet 11...Adhesive layer 12a, 12b...Release sheet

Claims

1. A pressure-sensitive adhesive sheet having at least a pressure-sensitive adhesive layer, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains a polymer having a main chain obtained by copolymerizing an acrylic monomer and a cyclodextrin derivative having a polymerizable group, the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is less than 10%, The pressure-sensitive adhesive layer has a 500% modulus of 0.02 N / mm 2 or more and 5 N / mm 2 or less when subjected to a tensile test at 23°C. A pressure-sensitive adhesive sheet characterized by:

2. A pressure-sensitive adhesive sheet having at least a pressure-sensitive adhesive layer, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains a polymer having a main chain obtained by copolymerizing an acrylic monomer and a cyclodextrin derivative having a polymerizable group, the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is less than 10%, The content of the cyclodextrin derivative is such that the molar ratio of the total amount of the acrylic monomers is 0.5 or more and 10 or less, when the total amount of the acrylic monomers is taken as 100 mol. A pressure-sensitive adhesive sheet characterized by:

3. The 500% modulus of the pressure-sensitive adhesive layer when subjected to a tensile test at 23°C is 0.02 N / mm 2 or more and 5 N / mm 2 or less. The pressure-sensitive adhesive sheet according to claim 2 .

4. The adhesive strength of the adhesive layer to soda lime glass is P1 (N / 25 mm), When the adhesive strength of the reformed adhesive layer formed from the adhesive solution obtained by dissolving the adhesive layer to soda lime glass is P2 (N / 25 mm), The adhesive strength ratio of P2 to P1 (P2 / P1) is 0.5 or more and less than 1.

47. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3.

5. The mass per unit volume of the adhesive layer is M1 (mg), The adhesive solution obtained by dissolving the adhesive layer of a unit volume is filtered through a Tetron mesh #200, and the mass of the adhesive after drying is defined as M2 (mg), The mass ratio of M2 to M1 (M2 / M1) is 0.7 or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4.

6. 6. The pressure-sensitive adhesive sheet according to claim 1, wherein the polymerizable group of the cyclodextrin derivative is a group containing a polymerizable unsaturated double bond.

7. 7. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive does not contain a guest molecule that can be included in the cyclodextrin derivative.

8. 8. The pressure-sensitive adhesive sheet according to claim 1, wherein the sol portion of the pressure-sensitive adhesive has a weight average molecular weight of 100,000 or more and 3,000,000 or less, as determined by gel permeation chromatography.

9. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the glass transition temperature (Tg) of the polymer is higher than -55°C and 20°C or lower.

10. The pressure-sensitive adhesive sheet has two release sheets, The pressure-sensitive adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9.

11. A method for producing the adhesive sheet according to any one of claims 1 to 10, comprising: a pressure-sensitive adhesive composition containing an acrylic monomer and a cyclodextrin derivative having a polymerizable group is applied to form a coating film; The coating film is irradiated with active energy rays to copolymerize the acrylic monomer and the cyclodextrin derivative, thereby forming a pressure-sensitive adhesive layer. A method for producing a pressure-sensitive adhesive sheet, comprising:

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