Adhesive and adhesive sheet

Abstract

To provide an adhesive and an adhesive sheet which are excellent in instantaneous adhesiveness and can be recycled.SOLUTION: An adhesive which contains a non-polymerizable cyclodextrin compound does not fall in the conditions of a test temperature of 40°C, an adhesive area of 25 mm×25 mm, a load of 9.8 N and a retention time of 3 hours when performing a retention test based on JIS Z0237:2009 of adhering an adhesive layer (11) of a thickness of 50 μm, having a gel fraction of 30% or less and comprising the adhesive to a soda lime glass.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive and 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] Pressure-sensitive adhesive sheets are used to fix various adherends, and depending on the application, they are required to be able to be attached to the adherend instantly.

[0008] The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide an adhesive and an adhesive sheet that are excellent in instant application properties and are recyclable. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, first, the present invention provides an adhesive containing a non-polymerizable cyclodextrin compound, characterized in that the adhesive has a gel fraction of 30% or less, and when a 50 μm thick adhesive layer made of the adhesive is attached to soda-lime glass and subjected to a holding strength test in accordance with JIS Z0237:2009, the adhesive does not fall off under the following conditions: test temperature 40°C, application area 25 mm × 25 mm, load 9.8 N, and holding time 3 hours (Invention 1).

[0010] The pressure-sensitive adhesive according to the above invention (Invention 1) contains a non-polymerizable cyclodextrin compound and has a gel fraction of 30% or less, which gives it excellent solvent solubility and makes it recyclable. That is, by immersing the pressure-sensitive adhesive in a predetermined solvent, the pressure-sensitive adhesive dissolves in the solvent and falls off from the substrate, etc. The pressure-sensitive adhesive dissolved in the solvent can be reused by volatilizing the solvent, etc. Furthermore, because the pressure-sensitive adhesive contains a non-polymerizable cyclodextrin compound, has a gel fraction of 30% or less, and satisfies the above conditions for holding power, it has excellent instantaneous adhesion (instant adhesion) and can maintain its adhesion state for a long period of time.

[0011] In the above invention (Invention 1), the weight-average molecular weight of the non-polymerizable cyclodextrin compound is preferably 500 or more and 5,000 or less (Invention 2).

[0012] In the above inventions (Inventions 1 and 2), it is preferable that, as a result of measurement by gel permeation chromatography, there are multiple peaks in the range of weight-average molecular weight of 500 or more, and the ratio of the area of ​​the peak having the largest area to the area of ​​the peak having the second largest area is 1 or more and 40 or less (Invention 3).

[0013] In the above inventions (Inventions 1 to 3), the storage modulus G'(25) at 25°C is preferably 0.01 MPa or more and 10 MPa or less (Invention 4).

[0014] In the above inventions (Inventions 1 to 4), the storage modulus G'(40) at 40°C is preferably 0.01 MPa or more and 10 MPa or less (Invention 5).

[0015] In the above inventions (Inventions 1 to 5), it is preferable that the ratio of the storage modulus G'(40) at 40°C to the storage modulus G'(25) at 25°C is 0.01 or more and 1 or less (Invention 6).

[0016] In the above inventions (Inventions 1 to 6), the Young's modulus is preferably 0.01 MPa or more and 10 MPa or less (Invention 7).

[0017] In the above inventions (Inventions 1 to 7), the sheet is molded to a thickness of 500 μm and a width of 10 mm, and when stretched to the breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min under an environment of 23°C and 50% RH, the breaking energy is 1.40 MJ / m 3 It is preferable that the above is true (Invention 8).

[0018] In the above inventions (inventions 1 to 8), an acrylic pressure-sensitive adhesive is preferred (invention 9).

[0019] In the above inventions (Inventions 1 to 9), it is preferable to contain a (meth)acrylic acid ester polymer and the non-polymerizable cyclodextrin compound (Invention 10).

[0020] In the above invention (Invention 10), the (meth)acrylic acid ester polymer is preferably one polymerized by solution polymerization (Invention 11).

[0021] Secondly, the present invention provides an adhesive sheet having at least an adhesive layer, characterized in that the adhesive constituting the adhesive layer is the adhesive described above (Inventions 1 to 11) (Invention 12).

[0022] In the above invention (Invention 12), it is preferable that the adhesive strength after 24 hours of application to soda lime glass is 5 N / 25 mm or more (Invention 13).

[0023] In the above inventions (Inventions 12 and 13), it is preferable that the adhesive strength after 1 minute of application to soda lime glass is 5 N / 25 mm or more (Invention 14).

[0024] In the above inventions (Inventions 12 to 14), the ratio of adhesive strength after 1 minute of application to soda lime glass to adhesive strength after 24 hours of application to soda lime glass is preferably 33% or more (Invention 15).

[0025] In the above inventions (Inventions 12 to 15), it is preferable that the arithmetic mean roughness Ra of at least one surface of the pressure-sensitive adhesive layer is 150 nm or less (Invention 16).

[0026] In the above inventions (Inventions 12 to 16), it is preferable that the adhesive sheet has two release sheets, and the adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 17). [Effects of the Invention]

[0027] The adhesive and adhesive sheet according to the present invention are excellent in instantaneous adhesion, can maintain the adhesion state for a long period of time, and furthermore, the adhesive can be recycled. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the present invention will be described. [Adhesive] The pressure-sensitive adhesive according to one embodiment of the present invention preferably contains a non-polymerizable cyclodextrin compound and has a gel fraction of 30% or less. When a 50 μm-thick pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is attached to soda-lime glass and subjected to a holding strength test in accordance with JIS Z0237:2009, it preferably does not fall off under the following conditions: test temperature 40°C, application area 25 mm × 25 mm, load 9.8 N, and holding time 3 hours.

[0030] The method for measuring the gel fraction in this specification is as shown in the test examples described later. The details of the holding power test in this specification are as shown in the test examples described later.

[0031] The non-polymerizable cyclodextrin compound is a cyclodextrin compound that does not have a polymerizable functional group. The non-polymerizable cyclodextrin compound limits the entanglement of the polymer chains of the PSA, and its non-polymerization improves the mobility of the polymer chains. This allows the PSA according to this embodiment to wet and spread on the adherend in a short time.

[0032] The pressure-sensitive adhesive according to the present embodiment contains the non-polymerizable cyclodextrin compound and has a gel fraction of 30% or less, which results in excellent solvent solubility and makes the pressure-sensitive adhesive recyclable. That is, by immersing the pressure-sensitive adhesive according to the present embodiment in a predetermined solvent, the pressure-sensitive adhesive dissolves in the solvent and falls off from the substrate. The pressure-sensitive adhesive dissolved in the solvent can be reused by volatilizing the solvent.

[0033] The solvent for dissolving the adhesive (layer) during recycling is not particularly limited, but examples thereof 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.

[0034] Furthermore, the pressure-sensitive adhesive according to the present embodiment contains a non-polymerizable cyclodextrin compound, has a gel fraction of 30% or less, and satisfies the above-mentioned conditions for holding power, thereby providing excellent instantaneous adhesion (instantaneous adhesion) and maintaining the adhesion state for a long period of time. Specifically, the instantaneous adhesion is measured by producing a 10 mm wide pressure-sensitive adhesive sheet by laminating a 50 μm thick pressure-sensitive adhesive layer of the pressure-sensitive adhesive described above onto a 100 μm thick polyethylene film substrate. The pressure-sensitive adhesive sheet is then adhered to a 15 mm diameter curved surface (made of polyethylene) so that the sheet curves in the width direction. After 1 minute, no changes, such as peeling at the widthwise edges, are observed.

[0035] From the viewpoint of solvent solubility, the gel fraction of the pressure-sensitive adhesive according to this embodiment is preferably 30% or less, more preferably 20% or less, particularly preferably 12% or less, further preferably 8% or less, preferably 5% or less, and most preferably less than 5%. On the other hand, from the viewpoint of cohesive strength, the gel fraction of the pressure-sensitive adhesive according to this embodiment is preferably 0% or more, more preferably 0.1% or more.

[0036] The pressure-sensitive adhesive according to the present embodiment preferably has multiple peaks in the weight-average molecular weight range of 500 or more as measured by gel permeation chromatography (GPC). The ratio (PA1 / PA2) of the area of ​​the peak with the largest area (PA1) to the area of ​​the peak with the second largest area (PA2) is preferably 1 to 40, more preferably 1.4 to 32, particularly preferably 1.8 to 24, and even more preferably 2 to 18. This makes it easier to satisfy the above-mentioned physical properties, resulting in better solvent solubility, faster stress relaxation, and better instantaneous application. Details of the measurement of the pressure-sensitive adhesive by GPC in this specification are as shown in the test examples below, and the weight-average molecular weight is a value converted into standard polystyrene.

[0037] The storage modulus G' at 25°C of the pressure-sensitive adhesive according to this embodiment is preferably 0.01 to 10 MPa, more preferably 0.04 to 5 MPa, particularly preferably 0.08 to 1 MPa, even more preferably 0.10 to 0.50 MPa, and of these, preferably 0.12 to 0.25 MPa. This makes it easier to satisfy the physical properties described above, resulting in better instantaneous application and retention, while also making it easier to achieve good solvent solubility. The method for measuring the storage modulus in this specification is as shown in the test examples described below.

[0038] The storage modulus G' of the pressure-sensitive adhesive according to this embodiment at 40°C is preferably 0.01 to 10 MPa, more preferably 0.03 to 5 MPa, particularly preferably 0.05 to 1 MPa, even more preferably 0.06 to 0.50 MPa, and of these, preferably 0.07 to 0.20 MPa. This makes it easier to satisfy the physical properties described above, resulting in better instant application and holding power, while also making it easier to achieve good solvent solubility.

[0039] The ratio of the storage modulus G'(40) at 40°C to the storage modulus G'(25) at 25°C of the pressure-sensitive adhesive according to this embodiment (G'(40) / G'(25)) is preferably 0.01 to 1, more preferably 0.10 to 0.90, particularly preferably 0.20 to 0.80, even more preferably 0.30 to 0.70, and of these, preferably 0.40 to 0.60. This makes it easier to satisfy the above-mentioned physical properties, resulting in better instant application and holding power, while also making it easier to achieve good solvent solubility.

[0040] The Young's modulus of the pressure-sensitive adhesive according to the present embodiment is preferably 0.01 to 10 MPa, more preferably 0.04 to 5 MPa, particularly preferably 0.08 to 1 MPa, and even more preferably 0.10 to 0.70 MPa. This makes it easier to satisfy the physical properties described above, resulting in better instant application and retention, while also making it easier to achieve good solvent solubility. The method for measuring Young's modulus in this specification is as shown in the test examples described below.

[0041] The adhesive according to this embodiment was molded into a thickness of 500 μm and a width of 10 mm, and when stretched to the breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min under an environment of 23° C. and 50% RH, the breaking energy was 1.40 MJ / m 3 It is preferable that the concentration is 1.50MJ / m or more. 3 More preferably, it is 1.60 MJ / m or more, and particularly 1.60 MJ / m 3 It is preferable that the energy density is 1.65MJ / m or more, and more preferably 1.65MJ / m3 This provides superior instantaneous application and retention. On the other hand, from the viewpoint of achieving both instantaneous application and solvent solubility, the breaking energy is preferably 100 MJ / m or more. 3 Preferably, it is 50MJ / m or less. 3 More preferably, it is 10 MJ / m or less, and particularly 10 MJ / m 3 It is preferable that the ion exchange rate is 7.0 MJ / m or less, and more preferably 7.0 MJ / m 3 The details of the tensile test for measuring the breaking energy in this specification are as shown in the test examples described later.

[0042] The PSA according to the present embodiment contains a non-polymerizable cyclodextrin compound. The non-polymerizable cyclodextrin compound in this specification may be cyclodextrin itself or a cyclodextrin (cyclodextrin derivative) having a substituent other than a polymerizable functional group. Because the non-polymerizable cyclodextrin compound does not have a polymerizable functional group, the non-polymerizable cyclodextrin compound does not polymerize with itself or with other compounds, such as acrylic polymers or acrylic monomers, and maintains its original molecular weight.

[0043] The weight-average molecular weight of the non-polymerizable cyclodextrin compound in this embodiment is preferably 500 to 5000, more preferably 600 to 3500, particularly preferably 700 to 2000, and even more preferably 800 to 1700. This makes it easier to satisfy the above-mentioned physical properties, resulting in better solvent solubility, faster stress relaxation, and better instantaneous application. Note that the weight-average molecular weight of the non-polymerizable cyclodextrin compound in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0044] The pressure-sensitive adhesive according to the present embodiment is not particularly limited in type as long as it contains a non-polymerizable cyclodextrin compound and satisfies the above-described physical properties. For example, it may be any of an acrylic pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, a polyurethane pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, etc. Furthermore, the pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, a cross-linked type or a non-cross-linked type, and may be either non-curable with active energy rays or curable with active energy rays.

[0045] Among the above, acrylic adhesives are preferred because they easily satisfy the above-mentioned physical properties. The acrylic adhesive is preferably one that is not curable by active energy rays, particularly preferably a solvent-based adhesive, and more preferably a non-crosslinked type. From the perspective of the SDGs, the adhesive may be made of a material with a high biomass content, a recyclable or reusable material, or a recycled or reused material.

[0046] The adhesive according to the present embodiment preferably contains an acrylic polymer (particularly a solution-polymerized acrylic polymer) and a non-polymerizable cyclodextrin compound, and preferably does not contain a crosslinking agent. The non-polymerizable cyclodextrin compound is preferably one in which all hydroxyl groups of the cyclodextrin are substituted with non-reactive groups or low-reactive groups, and is particularly preferably one in which they are substituted with acyl groups, especially acetyl groups. By having the above composition, the above-mentioned physical properties are easily satisfied, the instantaneous application property is improved, and the adhesive that dissolves in a solvent during recycling can be easily reused, improving the recyclability of the adhesive.

[0047] The PSA according to the present embodiment preferably does not contain guest molecules that can be included in the non-polymerizable cyclodextrin compound. In this specification, "inclusion" refers to the phenomenon in which a low-molecular-weight guest molecule is incorporated into the cavity of a host molecule (cyclodextrin compound), excluding the inclusion of easily exchangeable solvent molecules and the phenomenon in which a polymer chain penetrates the interior. In this specification, "guest molecule" refers to a molecule that can be included in a cyclodextrin compound, 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 compounds, n-butyl acrylate, t-butyl acrylate, styrene, adamantyl acrylate, and isobornyl acrylate for β-cyclodextrin compounds, and octyl acrylate and dodecyl acrylate for γ-cyclodextrin compounds.

[0048] In this specification, the phrase "the PSA does not contain guest molecules that can be included in a non-polymerizable cyclodextrin compound" 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 non-polymerizable cyclodextrin compound. However, they may remain in small amounts after polymerization, and are therefore defined as above.

[0049] Specifically, the pressure-sensitive adhesive in this embodiment preferably contains a (meth)acrylic acid ester polymer (A) and a non-polymerizable cyclodextrin compound (B). In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0050] (1) Each ingredient (1-1) (Meth)acrylic acid ester polymer (A) The (meth)acrylic acid ester polymer (A) in this embodiment preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. This allows the polymer to exhibit good adhesiveness. The alkyl group may be linear or branched, or may have a cyclic structure.

[0051] From the viewpoint of adhesiveness, the (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms. Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (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 easily satisfying the above-mentioned physical properties, (meth)acrylic acid esters having an alkyl group carbon number of 2 to 8 are preferred, with ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isopentyl (meth)acrylate, or n-octyl (meth)acrylate being particularly preferred, and ethyl acrylate, n-butyl acrylate, isopentyl acrylate, or n-octyl acrylate being even more preferred. Isopentyl acrylate and n-octyl acrylate are also preferred from the viewpoint of the SDGs, since they can be provided as biomass monomers. These may be used alone or in combination of two or more.

[0052] Among these, from the viewpoint of more easily satisfying the aforementioned physical properties and from the viewpoint of the SDGs, a combination of n-butyl acrylate and n-octyl acrylate, or a combination of ethyl acrylate and isopentyl acrylate is preferred. When n-butyl acrylate and n-octyl acrylate are used in combination, the blending ratio (by mass) thereof is preferably 50:50 to 99:1, more preferably 60:40 to 96:4, particularly preferably 70:30 to 92:8, and even more preferably 80:20 to 90:10. When ethyl acrylate and isopentyl acrylate are used in combination, the blending ratio (by mass) thereof is preferably 50:50 to 99:1, more preferably 65:35 to 98:2, particularly preferably 75:25 to 97:3, and even more preferably 85:15 to 96:4.

[0053] The (meth)acrylic acid ester polymer (A) preferably contains 60 mass % or more, more preferably 70 mass % or more, particularly preferably 80 mass % or more, and even more preferably 90 mass % or more of (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer, with an upper limit of 100 mass % being preferred. This makes it easier to satisfy the above-mentioned physical properties and also allows suitable amounts of other monomer components such as functional group-containing monomers to be introduced into the (meth)acrylic acid ester polymer (A).

[0054] The (meth)acrylic acid ester polymer (A) preferably contains, as a monomer unit constituting the polymer, a functional group-containing monomer having a functional group in the molecule, and the presence of the functional group derived from the functional group-containing monomer can improve the compatibility between the (meth)acrylic acid ester polymer (A) and the non-polymerizable cyclodextrin compound (B).

[0055] Preferred examples of functional group-containing monomers include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), etc. Among these, carboxyl group-containing monomers are preferred from the viewpoint of improving the cohesion of the film (pressure-sensitive adhesive layer) through hydrogen bonding.

[0056] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoints of compatibility with the non-polymerizable cyclodextrin compound (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0057] The (meth)acrylic acid ester polymer (A) preferably contains 0.1 to 50 mass %, more preferably 1 to 35 mass %, particularly preferably 3 to 25 mass %, even more preferably 5 to 20 mass %, and especially preferably 8 to 15 mass % of functional group-containing monomers as monomer units constituting the polymer, which makes it possible to effectively improve the cohesion of the coating while maintaining good adhesiveness.

[0058] The (meth)acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. Examples of other monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

[0059] The (meth)acrylic acid ester polymer (A) is preferably a linear polymer, which is expected to facilitate entanglement of molecular chains and improve cohesive strength.

[0060] The (meth)acrylic acid ester polymer (A) may be a polymer obtained by solution polymerization, a polymer obtained without a solvent, or an emulsion polymerization. Among these, a solution polymer obtained by a solution polymerization method is preferred. By being a solution polymer, the solvent solubility becomes more excellent.

[0061] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0062] The weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 100,000 to 3,000,000, more preferably 200,000 to 2,000,000, particularly preferably 300,000 to 1,600,000, further preferably 400,000 to 1,200,000, and most preferably 500,000 to 800,000. This makes it easier to satisfy the above-mentioned physical properties, resulting in better instantaneous application and solvent solubility. The weight-average molecular weight of the (meth)acrylic acid ester polymer in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0063] In the pressure-sensitive adhesive according to this embodiment, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more.

[0064] The content of the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive according to this embodiment is preferably 70 to 100% by mass, more preferably 80.00 to 99.9% by mass, particularly preferably 90.00 to 99.8% by mass, even more preferably 95.00 to 99.5% by mass, and particularly preferably 95.22 to 99.20% by mass, thereby ensuring a sufficient content of the non-polymerizable cyclodextrin compound (B) and achieving good adhesive strength.

[0065] (1-2) Non-polymerizable cyclodextrin compound (B) In this embodiment, the cyclodextrin moiety of the non-polymerizable cyclodextrin compound (B) is preferably α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin, which may have a substituent other than a polymerizable functional group. Among these, β-cyclodextrin or γ-cyclodextrin is preferred from the viewpoint of easily satisfying the above-mentioned physical properties, and β-cyclodextrin having a substituent other than a polymerizable functional group or γ-cyclodextrin having a substituent other than a polymerizable functional group is particularly preferred.

[0066] The above-mentioned substituent is a group in which a hydroxyl group of cyclodextrin is substituted, and specific examples thereof include an acyl group, an alkyl group, a trityl group, a tosyl group, a trimethylsilane group, a phenyl group, etc., as well as a polyester chain, an oxyethylene chain, an alkyl chain, an ether chain, an ester chain, an acrylic ester chain, etc. Among the above, a substituent having lower reactivity than a hydroxyl group or a non-reactive substituent is preferred. From the viewpoint of making it easier to obtain a pressure-sensitive adhesive that satisfies the above-mentioned physical properties, the substituent is preferably an acyl group, and particularly preferably an acetyl group.

[0067] The polymerizable functional group is usually a group containing a polymerizable unsaturated double bond, particularly an ethylenically unsaturated group, and specific examples thereof include a (meth)acryloyl group, a vinyl group, and an allyl group.

[0068] In the non-polymerizable cyclodextrin compound (B), it is preferred that no hydroxyl groups remain in the cyclodextrin, and it is particularly preferred that all of the hydroxyl groups in the cyclodextrin be substituted with acyl groups, especially acetyl groups. Specifically, peracetylated cyclodextrin is preferred, and peracetylated β-cyclodextrin or peracetylated γ-cyclodextrin is particularly preferred.

[0069] The content of the non-polymerizable cyclodextrin compound (B) in the pressure-sensitive adhesive according to this embodiment is preferably 0.10 to 30 parts by mass, more preferably 0.40 to 20 parts by mass, particularly preferably 0.70 to 10 parts by mass, even more preferably 0.90 to 8 parts by mass, and especially preferably 0.95 to 6 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer (A). This makes it easier to satisfy the above-mentioned physical properties, and the resulting pressure-sensitive adhesive has better solvent solubility (recyclability) and instantaneous application properties.

[0070] (1-3) Other ingredients If desired, the pressure-sensitive adhesive according to the present embodiment may contain various additives that are commonly used in acrylic pressure-sensitive adhesives, such as a silane coupling agent, an anti-rust agent, an ultraviolet absorber, an infrared absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a refractive index adjuster, a colorant, and a filler.

[0071] (2) Preparation of adhesive The pressure-sensitive adhesive according to this embodiment can be produced by producing a (meth)acrylic acid ester polymer (A), mixing the resulting (meth)acrylic acid ester polymer (A) with a non-polymerizable cyclodextrin compound (B), and adding additives, etc., as desired.

[0072] The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. The polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, using a polymerization initiator as desired. However, the present invention is not limited to this, and the polymerization may be carried out without a solvent. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

[0073] Examples of the polymerization initiator include azo compounds, organic peroxides, etc., and two or more of them may be used in combination. In the polymerization step, the weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

[0074] Once the (meth)acrylic acid ester polymer (A) is obtained, the non-polymerizable cyclodextrin compound (B), and optionally additives, a dilution solvent, etc., are added to the solution of the (meth)acrylic acid ester polymer (A) and mixed thoroughly to obtain a solvent-diluted adhesive (coating solution). Note that when any of the above components is used in a solid state, or when precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted alone in a dilution solvent before being mixed with other components.

[0075] Examples of the dilution solvent 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.

[0076] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be selected appropriately depending on the situation. For example, the adhesive is diluted to a concentration of 10 to 60 mass %. The addition of a dilution solvent is not a necessary condition for obtaining the coating solution, and as long as the adhesive has a viscosity that allows coating, it is not necessary to add a dilution solvent. In this case, the adhesive becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) is itself used as the dilution solvent.

[0077] [Adhesive sheet] The pressure-sensitive adhesive sheet according to one embodiment of the present invention comprises at least a pressure-sensitive adhesive layer, and preferably has a release sheet laminated on one or both sides of the pressure-sensitive adhesive layer. Specific configurations of examples of pressure-sensitive adhesive sheets according to this embodiment are shown in Figures 1 and 2.

[0078] As shown in Figure 1, the adhesive sheet 1A of the first embodiment is composed of, from the bottom up, a release sheet 12, an adhesive layer 11 laminated on the release surface of the release sheet 12, and a substrate 13 laminated on the adhesive layer 11.

[0079] 2, the adhesive sheet 1B according to the second embodiment is composed of two release sheets 12a and 12b and an adhesive layer 11 sandwiched between the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 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.

[0080] 1. Components (1) Adhesive layer In both pressure-sensitive adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer 11 is made of the pressure-sensitive adhesive described above. The thickness of the pressure-sensitive adhesive layer 11 (measured in accordance with JIS K7130) is determined appropriately depending on the intended use of the pressure-sensitive adhesive sheets 1A and 1B, but 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 for excellent instantaneous application properties. The thickness of the pressure-sensitive adhesive layer 12 is preferably 3000 μm or less, more preferably 1000 μm or less, particularly preferably 600 μm or less, even more preferably 200 μm or less, and most preferably 100 μm or less. This improves the solvent solubility of the pressure-sensitive adhesive layer 12 and improves the recyclability of the pressure-sensitive adhesive. The pressure-sensitive adhesive layer 12 may be formed as a single layer or as a laminate of multiple layers.

[0081] (2) Base material There are no particular limitations on the substrate 13, and any substrate that is used as a substrate sheet for a normal pressure-sensitive adhesive sheet can be used. Examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin films such as polyethylene and polypropylene; cellophane; diacetyl cellulose film; triacetyl cellulose film; acetyl cellulose butyrate film; polyvinyl chloride film; polyvinylidene chloride film; polyvinyl alcohol film; ethylene-vinyl acetate copolymer film; polystyrene film; polycarbonate film; polymethylpentene film; polysulfone film; polyether ether ketone film; polyether sulfone film; polyetherimide film; fluororesin film; polyamide film; acrylic resin film; polyurethane resin film; norbornene polymer film; cyclic olefin polymer film; cyclic conjugated diene polymer film; and vinyl alicyclic hydrocarbon polymer film, or a laminate film thereof; woven or nonwoven fabrics using fibers such as rayon, acrylic, or polyester; papers such as fine paper, glassine paper, impregnated paper, and coated paper; metal foils such as aluminum and copper; foams such as urethane foam and polyethylene foam; and laminates of two or more of these. From the perspective of the SDGs, the material constituting the base material 13 may be a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material.

[0082] The substrate 13 may be a desired optical member, such as a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, or a semi-transmissive reflective film.

[0083] The thickness of the substrate 13 varies depending on the type and application, but is usually preferably 10 to 300 μm, particularly preferably 20 to 200 μm, and further preferably 30 to 100 μm.

[0084] (3) Release sheet The release sheets 12, 12a, 12b protect the adhesive layer 13 until the adhesive sheets 1A, 1B are used, and are peeled off when the adhesive sheets 1A, 1B (adhesive layer 11) are used.

[0085] Examples of materials that can be used as the release sheets 12, 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 may also be used. From the perspective of the SDGs, the material constituting the release sheets may be a highly biomass material, a recyclable or reusable material, or a recycled or reused material.

[0086] The release surfaces of the release sheets 12, 12a, and 12b (particularly the surfaces that come into 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. It is preferable that one of the release sheets 12a and 12b be a heavy-release type release sheet with a high release strength, and the other be a light-release type release sheet with a low release strength.

[0087] There are no particular restrictions on the thickness of the release sheets 12, 12a, 12b, but it is generally preferably 20 to 200 μm, more preferably 30 to 120 μm.

[0088] 2. Manufacturing method To manufacture the adhesive sheet 1A, a coating solution of the adhesive is applied to the release surface of the release sheet 12, followed by drying to form the adhesive layer 11, and then the substrate 13 is laminated on the adhesive layer 11.

[0089] In addition, to manufacture the adhesive sheet 1B, a coating solution of the above adhesive is applied to the release surface of one release sheet 12a (or 12b), and a drying process is performed to form an adhesive layer 11, and then the release surface of the other release sheet 12b (or 12a) is superimposed on the adhesive layer 11.

[0090] The adhesive coating solution can be applied by, for example, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, or the like.

[0091] The drying treatment can usually be carried out by volatilizing the dilution solvent, etc., through a heat treatment. The heating temperature for the heat treatment is preferably 50 to 150° C., and more preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes.

[0092] 3. Physical Properties (1) Adhesive strength The adhesive strength of the adhesive sheets 1A, 1B (adhesive layer 11) 24 hours after application to soda lime glass is preferably 5 N / 25 mm or more, more preferably 8 to 40 N / 25 mm, particularly preferably 10 to 30 N / 25 mm, even more preferably 11 to 25 N / 25 mm, and even more preferably 12 to 23 N / 25 mm. When the lower limit of the adhesive strength is as above, the above-mentioned physical properties are easily obtained, and the desired adhesive durability is also easily obtained. Furthermore, when the upper limit of the adhesive strength is as above, good reworkability is obtained.

[0093] The adhesive strength of the adhesive sheets 1A, 1B (adhesive layer 11) one minute after application to soda lime glass is preferably 5 N / 25 mm or more, more preferably 6 to 40 N / 25 mm, particularly preferably 6.5 to 30 N / 25 mm, and even more preferably 7 to 20 N / 25 mm. When the lower limit of the adhesive strength is within the above range, the aforementioned physical properties are easily obtained, and instantaneous application is more excellent. Furthermore, when the upper limit of the adhesive strength is within the above range, good reworkability is obtained.

[0094] 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, where 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 1 minute or 24 hours under conditions of normal pressure, 23°C, and 50% RH, and then measured at a peel speed of 300 mm / min.

[0095] In the pressure-sensitive adhesive sheets 1A and 1B (pressure-sensitive adhesive layer 11), the ratio (%) of the adhesive strength 1 minute after application to soda-lime glass to the adhesive strength 24 hours after application to soda-lime glass is preferably 33% or more, more preferably 43% or more, particularly preferably 53% or more, even more preferably 63% or more, and of these, preferably 73% or more. This results in superior instantaneous application properties. Furthermore, the adhesive strength ratio (%) is preferably 500% or less, more preferably 300% or less, particularly preferably 200% or less, even more preferably 100% or less, and of these, preferably 90% or less. This makes it easier to satisfy the aforementioned physical property of holding power.

[0096] (2) Surface roughness The arithmetic mean roughness Ra of at least one surface of the pressure-sensitive adhesive layer 11 (preferably the surface to be attached to the desired adherend) is preferably 150 nm or less, more preferably 125 nm or less, particularly preferably 100 nm or less, even more preferably 92 nm or less, and especially preferably 85 nm or less. This results in better instantaneous application. Furthermore, from the viewpoint of ensuring a sufficient surface area in contact with the solvent during solvent immersion, the arithmetic mean roughness Ra is preferably 1 nm or more, more preferably 10 nm or more, especially preferably 40 nm or more, even more preferably 60 nm or more, especially preferably 70 nm or more, and most preferably 79 nm or more. In this embodiment, the use of a non-polymerizable cyclodextrin compound (B) with no residual hydroxyl groups makes it easier to achieve the above-mentioned small arithmetic mean roughness Ra. The method for measuring the arithmetic mean roughness Ra of the surface of the pressure-sensitive adhesive layer in this specification is as shown in the test examples described below.

[0097] (3) Haze value The haze value of the pressure-sensitive adhesive layer 11 is preferably 20% or less, more preferably 10% or less, particularly preferably 5% or less, even more preferably 3% or less, and most preferably 1% or less, and most preferably 0.5% or less. This provides very high transparency and makes the pressure-sensitive adhesive layer suitable for optical applications (displays), for example. On the other hand, there is no particular restriction on the lower limit of the haze value of the pressure-sensitive adhesive layer. The lower limit may be 0%. Here, the haze value in this specification is a value measured in accordance with JIS K7136:2000.

[0098] (4) Total light transmittance The total light transmittance of the pressure-sensitive adhesive layer 11 is preferably 80% or more as a lower limit, more preferably 90% or more, particularly preferably 95% or more, and even more preferably 99% or more. The pressure-sensitive adhesive layer having a total light transmittance within the above range makes it suitable for optical applications (displays), for example. On the other hand, the upper limit of the total light transmittance of the pressure-sensitive adhesive layer is not particularly limited, but is typically 100% or less. The total light transmittance in this specification is a value measured in accordance with JIS K7361-1:1997.

[0099] 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.

[0100] For example, release sheet 12 in pressure-sensitive adhesive sheet 1A may be omitted, and either release sheet 12a or 12b in pressure-sensitive adhesive sheet 1B may be omitted.

[0101] 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]

[0102] 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.

[0103] [Production Example 1] As the non-polymerizable cyclodextrin compound (B), peracetylated β-cyclodextrin represented by the following formula (1) was produced by the following procedure.

[0104] 1.8 g of β-cyclodextrin (Nacalai Tesque) and 47 mg of p-toluenesulfonic acid monohydrate as a catalyst were added to 8.5 ml of isopropenyl acetate as a solvent, and the mixture was reacted for 16 hours at 70° C. The reaction solution was evaporated under reduced pressure, and the resulting solid was washed with a 10% by mass aqueous solution of sodium carbonate, extracted with chloroform, and recrystallized with acetone to obtain 2.5 g of white solid peracetylated β-cyclodextrin (PAcβCD). [ka] (In formula (1), Ac represents an acetyl group.)

[0105] The molecular weight of the peracetylated β-cyclodextrin was measured by the method described below, and was found to be a weight average molecular weight (Mw) of 1,460.

[0106] [Production Example 2] A peracetylated γ-cyclodextrin (corresponding to non-polymerizable cyclodextrin compound (B)) represented by the following formula (2) was produced in the same manner as in Production Example 1, except that γ-cyclodextrin (manufactured by Nacalai Tesque) was used instead of β-cyclodextrin (manufactured by Nacalai Tesque). [ka] (In formula (2), Ac represents an acetyl group.)

[0107] The molecular weight of the peracetylated γ-cyclodextrin was measured by the method described below, and was found to be a weight average molecular weight (Mw) of 1,640.

[0108] Example 1 1. Preparation of (meth)acrylic acid ester polymer A (meth)acrylic acid ester polymer was prepared by copolymerizing 80 parts by mass of n-butyl acrylate, 10 parts by mass of n-octyl acrylate, and 10 parts by mass of acrylic acid by solution polymerization. The molecular weight of this (meth)acrylic acid ester polymer was measured by the method described below, and the weight average molecular weight (Mw) was 750,000.

[0109] 2. Preparation of adhesive coating solution 100 parts by mass of the (meth)acrylic acid ester polymer obtained above and 5 parts by mass of the cyclodextrin compound (peracetylated β-cyclodextrin) produced in Production Example 1 were mixed in ethyl acetate and thoroughly stirred to obtain a pressure-sensitive adhesive coating solution.

[0110] Here, the formulations (solid content equivalent) of each pressure-sensitive adhesive when the (meth)acrylic acid ester polymer is taken as 100 parts by mass (solid content equivalent) are shown in Table 1. Details of the abbreviations and the like shown in Table 1 are as follows. [(Meth)acrylic acid ester polymer] BA: n-butyl acrylate NOAA: n-octyl acrylate EA: Ethyl acrylate IAA: Isopentyl acrylate (isoamyl acrylate) AAc: acrylic acid [Cyclodextrin compounds] PAcβCD: Peracetylated β-cyclodextrin (Production Example 1) PAcγCD: Peracetylated γ-cyclodextrin (Production Example 2) MeβCD: Partially methylated β-cyclodextrin (Methyl-β-cyclodextrin, manufactured by Junsei Chemical Co., Ltd.) The molecular weight of the partially methylated β-cyclodextrin was measured by the method described below, and was found to be 1,584 in weight average molecular weight (Mw).

[0111] 3. Manufacturing of adhesive sheets The obtained adhesive coating solution was applied using a knife coater to the release-treated surface of a heavy-release type release sheet R1, one side of which had been treated with a silicone-based release agent for release of a polyethylene terephthalate film, and then heated at 90°C for 1 minute to form an adhesive layer.

[0112] Next, the adhesive layer on the release sheet R1 obtained above was bonded to a light-release type release sheet R2, one side of which was a polyethylene terephthalate film treated with a silicone-based release agent, so that the release-treated surface of the release sheet R2 was in contact with the adhesive layer, to produce an adhesive sheet consisting of release sheet R2 / adhesive layer (thickness: 50 μm) / release sheet R1.

[0113] The thickness of the adhesive layer was measured in accordance with JIS K7130 using a constant pressure thickness measuring device (manufactured by Teclock Corporation, product name "PG-02") (the same applies hereinafter). Furthermore, it was confirmed that the release strength of release sheet R1 was greater than that of release sheet R2 in the obtained adhesive sheet.

[0114] [Examples 2-3, Comparative Examples 1-5] Pressure-sensitive adhesive sheets were produced in the same manner as in Example 1, except that the type and ratio of each monomer constituting the (meth)acrylic acid ester polymer, the weight-average molecular weight of the (meth)acrylic acid ester polymer, the type, weight-average molecular weight and blending amount of the cyclodextrin compound, and the blending amount of the crosslinking agent were changed as shown in Table 1. In Comparative Examples 1 and 2, 0.05 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, an epoxy-based crosslinking agent, was used as the crosslinking agent.

[0115] The weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer and the cyclodextrin compound is a weight average molecular weight measured in terms of polystyrene using 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℃

[0116] [Test Example 1] (Measurement of gel fraction) The pressure-sensitive adhesive sheets produced 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.

[0117] 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.

[0118] [Test Example 2] (GPC measurement of adhesive) In Test Example 1, the sol component remaining after removing the pressure-sensitive adhesive from the ethyl acetate was subjected to gel permeation chromatography (GPC) measurement under the following conditions. <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℃

[0119] Furthermore, from the obtained molecular weight distribution graph, the area of ​​the peak with the largest area (PA1) and the area of ​​the peak with the second largest area (PA2) were calculated in the range of weight average molecular weight (polystyrene equivalent) 500 or more. The total peak area was also calculated. Next, the ratio (PA1 / PA2) of the area of ​​the peak with the largest area (PA1) to the area of ​​the peak with the second largest area (PA2) was calculated. The results are shown in Table 2.

[0120] Test Example 3 (Measurement of storage modulus G') The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples were laminated together to form a laminate with a thickness of 800 μm. A cylindrical body with a diameter of 8 mm (height of 800 μm) was punched out from the resulting pressure-sensitive adhesive layer laminate, and this was used as a sample.

[0121] The storage modulus G' of the above samples was measured under the following conditions using a viscoelasticity measuring instrument (manufactured by Anton Paar, product name "MCR302") by the torsional shear method in accordance with JIS K7244-6, and the storage modulus G'(25) (MPa) at 25°C and the storage modulus G'(40) (MPa) at 40°C were obtained. The results are shown in Table 2. Measurement frequency: 1Hz Heating rate: 5℃ / min Distortion: 1% Normal force: 1.0N Measurement temperature: -30℃~140℃

[0122] Furthermore, the ratio (G'(40) / G'(25)) of the storage modulus G'(40) at 40°C to the storage modulus G'(25) at 25°C obtained above was calculated. The results are shown in Table 2.

[0123] [Test Example 4] (Tensile test) The adhesive layers of the adhesive sheets produced in the Examples and Comparative Examples were laminated in multiple layers to a total thickness of 500 μm, and then a sample measuring 10 mm wide x 70 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 was elongated at a tensile speed of 200 mm / min using the tensile tester in an environment of 23°C and 50% RH. The sample was elongated until it broke, and the breaking energy (MJ / m 3 ) was measured. Furthermore, by the above tensile test, Young's modulus (MPa) was measured in accordance with JIS K7161:1994. The results are shown in Table 2.

[0124] [Test Example 5] (Measurement of relaxation time) The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples were laminated together to form a laminate with a thickness of 0.8 mm. A cylindrical object 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.

[0125] Using a viscoelasticity measuring device (manufactured by Anton Paar, product name "MCR302"), the sample was continuously strained by 10% under the following conditions in accordance with JIS K7244-1, and the relaxation modulus G(t) (MPa) was measured. From the measurement results, the maximum relaxation modulus G(t) max (MPa) and the maximum relaxation modulus G(t) max Measurements continued until 3757 seconds after the measurement. Measurement temperature: 25℃ Measurement points: 1000 points (logarithmic plot)

[0126] Obtained maximum relaxation modulus G(t) max The relaxation time (seconds) was the time elapsed until the first measurement point at which the relaxation modulus G(t) fell below 1 / e (where e is the base of the natural logarithm) relative to the applied pressure (MPa). The results are shown in Table 2.

[0127] [Test Example 6] (Measurement of adhesive strength) The release sheet R2 was peeled off from the pressure-sensitive adhesive sheets produced 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 "Cosmoshine A4360", thickness: 100 μm) having an easy-adhesion layer to obtain a release sheet R1 / adhesive layer / PET film laminate. The resulting laminate was cut into a width of 25 mm and a length of 100 mm.

[0128] The release sheet R1 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 at 23°C and 50% RH for 1 minute or 24 hours to prepare a sample. The adhesive strength (N / 25 mm) was then 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 Z0237:2022. The results are shown in Table 2.

[0129] The ratio (%) of the adhesive strength after 1 minute of application to the adhesive strength after 24 hours of application to the soda lime glass obtained above was also calculated. The results are shown in Table 2.

[0130] [Test Example 7] (Measurement of surface roughness) The release sheet R2 was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and the pressure-sensitive adhesive layer was fixed to a glass plate. Next, the release sheet R1 was peeled off from the pressure-sensitive adhesive sheet, and the surface of the exposed pressure-sensitive adhesive layer was observed at 50x magnification in PSI mode using an optical interference surface profiler (manufactured by Nippon Veeco Co., Ltd., product name "NT1100"), and the arithmetic mean roughness (Ra) (nm) was measured. Measurements were taken at 10 random locations within a 120 x 120 μm area on the surface profile image, and the average value was taken as the arithmetic mean roughness (Ra) (nm). The results are shown in Table 2.

[0131] [Test Example 8] (Haze Value Measurement) The adhesive layer of the adhesive sheet produced in the Examples and Comparative Examples was attached to glass to prepare a measurement sample. After background measurement was performed on the glass, the haze value (%) of the measurement sample was measured in accordance with JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000"). The results are shown in Table 2.

[0132] [Test Example 9] (Measurement of total light transmittance) The adhesive layer of the adhesive sheet produced in the Examples and Comparative Examples was attached to glass to prepare a measurement sample. After background measurement was performed on the glass, the total light transmittance (%) of the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0133] [Test Example 10] (Holding Force Test) The holding power test of the adhesive sheets was performed in accordance with JIS Z0237:2009, except for the procedures described below. The release sheet R2 was peeled off from the adhesive sheets produced in the Examples and Comparative Examples, and the exposed adhesive layer was attached to the easy-adhesion layer of a PET film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having an easy-adhesion layer, to obtain a release sheet R1 / adhesive layer / PET film laminate. The resulting laminate was cut to a width of 25 mm and a length of 125 mm.

[0134] Next, the release sheet R1 was peeled off from the laminate, and this was used as a sample. Only a 25 mm × 25 mm portion of the exposed adhesive layer of the sample was attached to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd.). The soda lime glass plate was then placed perpendicular to the ground, with the sample hanging from the soda lime glass plate, and left at 40°C for 15 minutes. Thereafter, the sample was left at 40°C for 3 hours while applying a load of 9.8 N. After 3 hours, the sample was checked for dropout and the holding power was evaluated according to the following criteria. The results are shown in Table 2. 〇...Did not fall. ×...Falled.

[0135] [Test Example 11] (Evaluation of instant adhesiveness) The release sheet R2 was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a PET film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having an easy-adhesion layer to obtain a release sheet R1 / adhesive layer / PET film laminate. The resulting laminate was cut into a width of 10 mm and a length of 50 mm.

[0136] Next, the release sheet R1 was peeled off from the laminate, and this was used as a sample. The exposed adhesive layer of the sample was adhered to the surface (curved surface) of a 15 mm diameter polyethylene cylindrical material (manufactured by Engineering Test Services, product name "PE Round Bar", 15φ x 300 mm) so that it was curved in the width direction, and the condition after 1 minute was visually observed. The instantaneous adhesiveness was then evaluated based on the following criteria. The results are shown in Table 2. ◎...No change ○: Peeling at the edge in the width direction is less than 5 mm ×: Peeling at the edge in the width direction is 5 mm or more

[0137] Test Example 12 (Evaluation of Solvent Solubility) The release sheet R2 was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a PET film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having an easy-adhesion layer to obtain a release sheet R1 / adhesive layer / PET film laminate. The resulting laminate was cut into a 50 mm × 50 mm piece.

[0138] The release sheet R1 was peeled off from the laminate, and the exposed adhesive layer was attached to a soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd.) to prepare a sample. The obtained sample was immersed in ethyl acetate and stirred for 24 hours, after which the state of the sample was visually observed. The solvent solubility of the adhesive (layer) was evaluated based on the following criteria. The results are shown in Table 2. ◯: The PET film was detached from the sample. ×: The PET film was not detached from the sample.

[0139] [Table 1]

[0140] [Table 2]

[0141] As can be seen from Table 2, the adhesives and adhesive sheets of the examples were excellent in instant adhesion and holding power, as well as in solvent solubility. [Industrial Applicability]

[0142] The pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present invention are suitable for applications requiring instant application, holding power, and recyclability. [Explanation of symbols]

[0143] 1A, 1B...Adhesive sheet 11...Adhesive layer 12, 12a, 12b...Release sheet 13...Base material

Claims

1. A pressure-sensitive adhesive containing a non-polymerizable cyclodextrin compound, The gel fraction is 30% or less, When a 50 μm thick adhesive layer made of the adhesive is attached to soda lime glass and subjected to a holding strength test in accordance with JIS Z0237:2009, it does not fall off under the conditions of a test temperature of 40° C., an attachment area of ​​25 mm×25 mm, a load of 9.8 N, and a holding time of 3 hours. A pressure-sensitive adhesive characterized by:

2. 2. The pressure-sensitive adhesive according to claim 1, wherein the weight-average molecular weight of the non-polymerizable cyclodextrin compound is 500 or more and 5,000 or less.

3. As a result of measurement by gel permeation chromatography, it has multiple peaks in the range of weight average molecular weight of 500 or more, The ratio of the area of ​​the peak having the largest area to the area of ​​the peak having the second largest area is 1 or more and 40 or less. The adhesive according to claim 1 .

4. 2. The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive has a storage modulus G'(25) at 25° C. of 0.01 MPa or more and 10 MPa or less.

5. 2. The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive has a storage modulus G'(40) at 40° C. of 0.01 MPa or more and 10 MPa or less.

6. 2. The pressure-sensitive adhesive according to claim 1, wherein the ratio of the storage modulus G'(40) at 40°C to the storage modulus G'(25) at 25°C is 0.01 or more and 1 or less.

7. 2. The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive adhesive has a Young's modulus of 0.01 MPa or more and 10 MPa or less.

8. The specimen was molded to a thickness of 500 μm and a width of 10 mm, and stretched to the breaking elongation at a measurement length of 20 mm and a tensile speed of 200 mm / min under an environment of 23°C and 50% RH. The breaking energy was 1.40 MJ / m ３ The adhesive according to claim 1, characterized in that

9. 2. The adhesive according to claim 1, which is an acrylic adhesive.

10. 2. The pressure-sensitive adhesive according to claim 1, comprising a (meth)acrylic acid ester polymer and the non-polymerizable cyclodextrin compound.

11. 11. The pressure-sensitive adhesive according to claim 10, wherein the (meth)acrylic acid ester polymer is polymerized by a solution polymerization method.

12. A pressure-sensitive adhesive sheet having at least a pressure-sensitive adhesive layer, The adhesive constituting the adhesive layer is the adhesive according to any one of claims 1 to 11. A pressure-sensitive adhesive sheet characterized by:

13. 13. The pressure-sensitive adhesive sheet according to claim 12, wherein the adhesive strength after 24 hours of application to soda-lime glass is 5 N / 25 mm or more.

14. 13. The pressure-sensitive adhesive sheet according to claim 12, wherein the adhesive strength after 1 minute of application to soda-lime glass is 5 N / 25 mm or more.

15. 13. The pressure-sensitive adhesive sheet according to claim 12, wherein the ratio of adhesive strength after 1 minute of application to soda-lime glass to adhesive strength after 24 hours of application to soda-lime glass is 33% or more.

16. The pressure-sensitive adhesive sheet according to claim 12, wherein the arithmetic mean roughness Ra of at least one surface of the pressure-sensitive adhesive layer is 150 nm or less.

17. 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 claim 12 .

Images