adhesive sheet

Abstract

To provide a pressure sensitive adhesive sheet capable of temporarily adhering an adherend in a detachable manner, the pressure sensitive adhesive sheet capable of exhibiting detachability with a low-power laser beam and eliminating a process of cleaning an adherend after detachment, with a narrow range of a detachment appearance location.SOLUTION: A pressure sensitive adhesive sheet includes an adhesive layer and a transfer layer arranged on one side of the adhesive layer. The transfer layer is a layer configured to harden with active energy ray irradiation. An adhesive force I at 23°C is 2 N / 20 mm or more when the adhesive layer of the pressure sensitive adhesive sheet is adhered onto glass. A ratio of the adhesive force I at 23°C when the adhesive layer of the pressure sensitive adhesive sheet is adhered onto glass is 5 or more with regard to an adhesive force B at 23°C after ultraviolet ray irradiation of 300 mJ / cm2 onto the transfer layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet. [Background technology]

[0002] When processing various components, such as electronic parts, it is common to temporarily fix the component to a support using an adhesive sheet, and then peel the processed component from the support after transportation, processing, etc. For example, Patent Document 1 describes a method in which a substrate (component to be processed) is processed while temporarily fixed to the support via an adhesive layer and a separation layer, and after processing, the separation layer is destroyed by irradiating it with laser light, peeling the substrate together with the adhesive layer from the support, and then removing the adhesive layer from the substrate. However, this method requires steps to remove the adhesive layer from the component and clean the non-adhesive surface of the component, which creates a problem in terms of production cost. Another problem is that the component may be damaged when irradiated with high-power laser light.

[0003] Furthermore, Patent Document 2 describes a method in which a plurality of workpieces are temporarily fixed to a carrier via an adhesive layer, and a laser beam is focused on the adhesive layer to generate blisters, thereby selectively separating and transferring portions of the workpieces from the carrier. However, this method has the problem that the blisters generated after laser irradiation spread over time, resulting in peeling of the carrier and unwanted detachment of workpieces that do not require transfer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5875850 [Patent Document 2] Patent No. 6053756 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an adhesive sheet that can temporarily fix an adherend in a releasable manner, in which releasability is exhibited by low-power laser light, which eliminates the need for a step of cleaning the adherend after peeling, and in which peeling occurs in a narrow area. [Means for solving the problem]

[0006] The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer and a transfer layer disposed on one side of the pressure-sensitive adhesive layer, wherein the transfer layer is a layer that is cured by irradiation with active energy rays, and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has an adhesive strength I at 23°C when attached to a glass plate of 2 N / 20 mm or more, and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has an adhesive strength I at 23°C when attached to a glass plate of 300 mJ / cm or more when attached to the transfer layer. 2 The ratio of adhesive strength B at 23°C after irradiation with ultraviolet light is 5 or more. In one embodiment, the pressure-sensitive adhesive sheet further comprises a substrate between the pressure-sensitive adhesive layer and the transfer layer. In one embodiment, 300 mJ / cm 2 After irradiation with ultraviolet light, the indentation modulus B of the transfer layer at 23°C is 5 times or more the indentation modulus I of the pressure-sensitive adhesive layer at 23°C. In one embodiment, the transfer layer contains an active energy ray-curable pressure-sensitive adhesive, and the active energy ray-curable pressure-sensitive adhesive contains an acrylic polymer as a base polymer. In one embodiment, the pressure-sensitive adhesive sheet is used to temporarily fix a member to a support, and after transportation and / or processing, the member is peeled off from the support by irradiating it with laser light. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an adhesive sheet that can temporarily fix an adherend in a releasable manner, in which releasability is exhibited by low-power laser light, which eliminates the need for a step of cleaning the adherend after peeling, and in which peeling occurs in a narrow area. [Brief explanation of the drawings]

[0008] [Figure 1] 1(a) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention, and FIG. 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. [Figure 2] 1(a) is a micrograph of the surface of the transfer layer in Example 1. FIG. 1(b) is a micrograph of the surface of the transfer layer in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Overview of adhesive sheets FIG. 1(a) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. Pressure-sensitive adhesive sheet 100 according to this embodiment comprises a pressure-sensitive adhesive layer 10 and a transfer layer 20 disposed on one side of the pressure-sensitive adhesive layer 10. FIG. 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. Pressure-sensitive adhesive sheet 200 according to this embodiment further comprises a substrate 30 between the pressure-sensitive adhesive layer 10 and the transfer layer 20. Although not shown, the pressure-sensitive adhesive sheet of the present invention may be provided with release liners on the outside of the pressure-sensitive adhesive layer and the transfer layer to protect the adhesive surface until use. The pressure-sensitive adhesive sheet may also further comprise any other appropriate layers as long as the effects of the present invention are obtained.

[0010] The pressure-sensitive adhesive sheet of the present invention can be used to temporarily fix a member to a support (e.g., a glass substrate) using the pressure-sensitive adhesive sheet, and then peel the member from the support after transportation, processing, etc. During peeling, laser light is irradiated, and only the member at the desired position can be peeled off with pinpoint accuracy.

[0011] The transfer layer is a layer that hardens when irradiated with active energy rays. More specifically, the transfer layer has adhesiveness for fixing an adherend, and is configured so that the adhesiveness is reduced when the layer is irradiated with active energy rays. Even after hardening, it is preferable that the adhesive strength remains strong enough to fix the adherend (for example, adhesive strength strong enough to prevent the adherend from falling off naturally). In one embodiment, the adhesive strength of the entire transfer layer is reduced by irradiating with active energy rays. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, and particle beams. Ultraviolet rays are preferred.

[0012] The pressure-sensitive adhesive layer may have any suitable configuration as long as the effects of the present invention are achieved. In one embodiment, the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive. The pressure-sensitive adhesive sheet can be used by adhering the pressure-sensitive adhesive layer to a support (e.g., a glass substrate). In the pressure-sensitive adhesive sheet, laser light irradiation causes partial strain in the pressure-sensitive adhesive layer (and the substrate in a configuration having a substrate), and this strain propagates to the transfer layer, causing a temporary shape change in the surface (adhesion surface) of the transfer layer, thereby enabling the adherend placed in that location to be peeled off. In the present invention, by adjusting the components of the pressure-sensitive adhesive layer (e.g., the type of base polymer; the type of additives such as tackifiers and crosslinking agents; and the amounts of these additives), the pressure-sensitive adhesive layer can absorb laser light of a predetermined wavelength, thereby making the pressure-sensitive adhesive layer more susceptible to strain. The substrate can also be made to be a substrate that is more susceptible to strain by appropriately selecting its constituent materials. Furthermore, as described above, laser light irradiation after curing the transfer layer can favorably exhibit releasability due to strain propagation. In the present invention, the above-mentioned action allows the release property to be exhibited, eliminating the need for a high-power laser beam, eliminating the need for a step of cleaning the adherend after release, and allowing the release to occur in a narrow area. Furthermore, after release, the change in the surface shape of the transfer layer does not persist (i.e., it does not expand over time, but rather can return to the shape before the change), thereby preventing problems such as unwanted detachment of the adherend in areas where release is not desired.

[0013] The adhesive strength I at 23°C when the adhesive layer of the pressure-sensitive adhesive sheet is adhered to a glass plate is 2 N / 20 mm or more. By increasing the adhesive strength I, it is possible to optimize the deformation of each layer due to laser light irradiation, narrow the range of locations where peeling occurs, and prevent problems such as unwanted detachment of the adherend in locations where peeling is not desired. The adhesive strength I is preferably 2 N / 20 mm to 25 N / 20 mm, and more preferably 5 N / 20 mm to 20 N / 20 mm. Within this range, the effects of the present invention are remarkable. The adhesive strength is measured in accordance with JIS Z 0237:2000. Specifically, the adhesive layer of the adhesive sheet is adhered to a glass plate (arithmetic mean surface roughness Ra: 50±25 nm) using a 2 kg roller going back and forth once, and then left at 23°C for 30 minutes. After that, the adhesive sheet is peeled off at a peel angle of 180° and a peel speed (pulling speed) of 300 mm / min to measure the adhesiveness.

[0014] The initial adhesive strength A at 23°C immediately after the transfer layer of the pressure-sensitive adhesive sheet is attached to the stainless steel plate is preferably 1 N / 20 mm to 20 N / 20 mm, more preferably 1.5 N / 20 mm to 15 N / 20 mm, and even more preferably 2 N / 20 mm to 10 N / 20 mm. Within these ranges, a pressure-sensitive adhesive sheet capable of favorably holding an adherend can be obtained. The adhesive strength of the transfer layer side is also measured in accordance with JIS Z 0237:2000. Specifically, the transfer layer of the pressure-sensitive adhesive sheet is attached to a stainless steel plate (arithmetic mean surface roughness Ra: 50±25 nm) using a 2 kg roller in one reciprocating motion, and the sheet is left to stand at 23°C for 30 minutes. After this, the adhesive strength is measured by peeling the sheet off at a peel angle of 180° and a peel speed (pulling speed) of 300 mm / min. The adhesive strength of the transfer layer changes upon irradiation with active energy rays and laser light, and in this specification, "initial adhesive strength" means the adhesive strength before irradiation with active energy rays and laser light.

[0015] In one embodiment, the pressure-sensitive adhesive sheet is attached to the stainless steel plate, and the transfer layer is exposed to 300 mJ / cm 2 2The adhesive strength B at 23°C after irradiation with ultraviolet light (also referred to as post-curing adhesive strength B) is preferably 1 N / 20 mm or less, more preferably 0.5 N / 20 mm or less, even more preferably 0.2 N / 20 mm or less, and particularly preferably 0.1 N / 20 mm or less. Within these ranges, a pressure-sensitive adhesive sheet with excellent releasability and little adhesive residue can be obtained. The lower limit of the post-curing adhesive strength B is, for example, 0.01 N / 20 mm (preferably 0.001 N / 20 mm). The ultraviolet light irradiation can be carried out, for example, using an ultraviolet light irradiation device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810") and ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, accumulated light amount: 300 mJ / cm). 2 The ultraviolet irradiation can be carried out from the pressure-sensitive adhesive layer side.

[0016] The ratio of the adhesive strength I at 23°C when the pressure-sensitive adhesive layer is attached to glass to the adhesive strength B after curing of the transfer layer (adhesive strength I / adhesive strength B after curing) is 5 or more. In other words, in the pressure-sensitive adhesive sheet, the adhesive strength B after curing is 0.2 times or less (preferably 0.1 times or less, more preferably 0.05 times or less, and even more preferably 0.005 times or less) of the adhesive strength I. By specifying (adhesive strength I / adhesive strength B after curing) as above, it is possible to optimize the deformation of each layer due to laser light irradiation and to obtain an adhesive sheet with excellent releasability due to laser light irradiation. Such an adhesive sheet can achieve reliable releasability within a narrow range. (Adhesive strength I / adhesive strength B after curing) is preferably 10 or more, more preferably 20 or more, and even more preferably 200 or more. Within this range, the effects of the present invention are remarkable. The upper limit of (adhesive strength I / adhesive strength B after curing) is, for example, 1,000, preferably 5,000, and more preferably 10,000. That is, in the pressure-sensitive adhesive sheet, the adhesive strength B after curing can be 0.0001 times the adhesive strength I or more.

[0017] The ratio of the initial adhesive strength A of the transfer layer to the adhesive strength B of the transfer layer after curing (initial adhesive strength A / adhesive strength B after curing) is preferably 5 or more, more preferably 10 or more, more preferably 10 to 100, and even more preferably 30 to 80. Within these ranges, a pressure-sensitive adhesive sheet can be obtained that has an excellent balance between fixation to an adherend and releasability.

[0018] In the pressure-sensitive adhesive sheet, the anchoring strength between the pressure-sensitive adhesive layer and a layer (e.g., a transfer layer, a substrate, or other layer) disposed in contact with the pressure-sensitive adhesive layer at 23°C is preferably 2 N / 20 mm or more, more preferably 4 N / 20 mm or more, even more preferably 6 N / 20 mm or more, and particularly preferably 8 N / 20 mm or more. The upper limit of the anchoring strength is, for example, 30 N / 20 mm (preferably 50 N / 20 mm). The anchoring strength is measured by peeling the pressure-sensitive adhesive layer from the adjacent layer at 23°C, a peel angle of 180°, and a peel speed (tensile speed) of 300 mm / min.

[0019] In the pressure-sensitive adhesive sheet, the anchoring strength between the transfer layer and a layer (e.g., a pressure-sensitive adhesive layer, a substrate, or other layer) disposed in contact with the transfer layer at 23°C is preferably 2 N / 20 mm or more, more preferably 4 N / 20 mm or more, even more preferably 6 N / 20 mm or more, and particularly preferably 8 N / 20 mm or more. The upper limit of the anchoring strength is, for example, 30 N / 20 mm (preferably 50 N / 20 mm). The anchoring strength is measured by peeling the transfer layer from the adjacent layer at 23°C, a peeling angle of 180°, and a peeling speed (tensile speed) of 300 mm / min.

[0020] The light transmittance at a wavelength of 248 nm of the pressure-sensitive adhesive sheet of the present invention is preferably 50% or less, more preferably 30% or less, even more preferably 10% or less, and particularly preferably 5% or less. In one embodiment, the light transmittance at a wavelength of 248 nm of the pressure-sensitive adhesive sheet can be controlled by the light transmittance of the pressure-sensitive adhesive layer and / or substrate. Specifically, the transmittance is controlled by adjusting the components of the pressure-sensitive adhesive layer (e.g., the type of base polymer; the type of additives such as tackifiers and crosslinkers; and their blending amounts), the thickness of the pressure-sensitive adhesive layer, the constituent materials of the substrate, the thickness of the substrate, etc. In the present invention, reducing the light transmittance promotes the generation of distortion in the pressure-sensitive adhesive layer and / or substrate, thereby enabling a reduction in the laser output required for peeling. Because the pressure-sensitive adhesive sheet of the present invention exhibits releasability with a low-output laser beam, use of the pressure-sensitive adhesive sheet reduces damage to the adherend during peeling and prevents breakage of the adherend. The lower the light transmittance at a wavelength of 248 nm, the better, with the lower limit being, for example, 0.5% (preferably 0%).

[0021] The light transmittance of the pressure-sensitive adhesive sheet of the present invention at a wavelength of 365 nm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. Within this range, a pressure-sensitive adhesive sheet can be obtained in which the transfer layer is preferably cured by irradiation with active energy rays. The higher the light transmittance of the pressure-sensitive adhesive sheet at a wavelength of 365 nm, the better, but the upper limit is, for example, 95% (preferably 100%).

[0022] The haze value of the pressure-sensitive adhesive sheet of the present invention is preferably 70% or less, more preferably 65% ​​or less. Within this range, a pressure-sensitive adhesive sheet can be obtained in which the transfer layer is preferably cured by irradiation with active energy rays. In one embodiment, the haze value of the pressure-sensitive adhesive sheet is 20% or less. The lower the haze value of the pressure-sensitive adhesive sheet, the better, and the lower limit is, for example, 0.1%.

[0023] The thickness of the pressure-sensitive adhesive sheet is preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm. In one embodiment, the thickness of the pressure-sensitive adhesive sheet is 30 μm or less. If the pressure-sensitive adhesive sheet is thin, strain generated in the pressure-sensitive adhesive layer is easily propagated to the transfer layer, and a pressure-sensitive adhesive sheet with excellent releasability can be obtained.

[0024] When the pressure-sensitive adhesive sheet further comprises a substrate and / or any other appropriate layer, the distance between the pressure-sensitive adhesive layer and the transfer layer is preferably less than 50 μm, more preferably 30 μm or less, even more preferably 25 μm or less, and particularly preferably 10 μm or less. Within such a range, strain generated in the pressure-sensitive adhesive layer is easily propagated to the transfer layer, and a pressure-sensitive adhesive sheet with excellent releasability can be obtained.

[0025] B. Transfer layer The thickness of the transfer layer is preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 3 μm to 10 μm.Within such a range, the above effects become prominent.

[0026] The initial indentation elastic modulus A of the transfer layer at 23°C is preferably 0.1 MPa or more but less than 14 MPa, more preferably 0.1 MPa to 10 MPa, and even more preferably 0.2 MPa to 8 MPa. Within this range, a pressure-sensitive adhesive sheet with excellent fixation can be obtained. The indentation elastic modulus can be measured by a single indentation method at 23°C, with an indentation speed of 10 nm / s and an indentation depth of 100 nm. The adhesive strength of the transfer layer changes upon irradiation with active energy rays and laser light, and in this specification, "initial indentation elastic modulus A" refers to the adhesive strength before irradiation with active energy rays and laser light.

[0027] The transfer layer is 300 mJ / cm 2After irradiation with ultraviolet light, the layer preferably has an indentation modulus B (also referred to as post-curing modulus B) at 23°C of 14 MPa or more, more preferably 15 MPa or more, even more preferably 20 MPa or more, and particularly preferably 50 MPa or more. Within these ranges, a pressure-sensitive adhesive sheet with excellent releasability can be obtained. Furthermore, contamination of the adherend during peeling can be prevented. The upper limit of the post-curing modulus B at 23°C is, for example, 500 MPa (preferably 300 MPa).

[0028] The transfer layer is 300 mJ / cm 2 After irradiation with ultraviolet light, the indentation modulus B at 23°C is preferably at least 20 times, more preferably at least 30 times, even more preferably 30 to 1000 times, and particularly preferably 50 to 200 times the initial indentation modulus A of the transfer layer at 23°C. Within these ranges, a pressure-sensitive adhesive sheet with an excellent balance between adherend fixation and releasability can be obtained.

[0029] The transfer layer is 300 mJ / cm 2 After irradiation with ultraviolet light, the indentation modulus B at 23°C is preferably at least 5 times, more preferably at least 10 times, even more preferably 50 to 5000 times, and particularly preferably 100 to 3000 times the indentation modulus I at 23°C of the pressure-sensitive adhesive layer. Within such a range, it is possible to optimize the deformation of each layer due to laser light irradiation, and to obtain a pressure-sensitive adhesive sheet that has excellent releasability due to laser light irradiation. Such a pressure-sensitive adhesive sheet can achieve reliable releasability within a narrow range.

[0030] In one embodiment, the transfer layer contains an active energy ray-curable adhesive. The active energy ray-curable adhesive may further contain an ultraviolet absorber and / or a photopolymerization initiator.

[0031] (Active energy ray curable adhesive) In one embodiment, an active energy ray-curable adhesive (A1) is used as the active energy ray-curable adhesive, which comprises a base polymer as a matrix and an active energy ray-reactive compound (monomer or oligomer) capable of bonding to the base polymer. In another embodiment, an active energy ray-curable adhesive (A2) is used, which comprises an active energy ray-reactive polymer as the base polymer. Preferably, the base polymer has a functional group capable of reacting with a photopolymerization initiator. Examples of such functional groups include a hydroxyl group and a carboxyl group.

[0032] Examples of base polymers used in the PSA (A1) include rubber-based polymers such as natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, reclaimed rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber (NBR); silicone-based polymers; and acrylic-based polymers. These polymers may be used alone or in combination of two or more. Among these, acrylic polymers are preferred.

[0033] Examples of acrylic polymers include homopolymers or copolymers of hydrocarbon group-containing (meth)acrylic acid esters, such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters; and copolymers of such hydrocarbon group-containing (meth)acrylic acid esters with other copolymerizable monomers. Examples of (meth)acrylic acid alkyl esters include the methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester (i.e., lauryl ester), tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, and eicosyl ester of (meth)acrylic acid. Examples of (meth)acrylic acid cycloalkyl esters include the cyclopentyl ester and cyclohexyl ester of (meth)acrylic acid. Examples of (meth)acrylic acid aryl esters include phenyl (meth)acrylate and benzyl (meth)acrylate. The content of the structural unit derived from the hydrocarbon group-containing (meth)acrylic acid ester is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, per 100 parts by weight of the base polymer.

[0034] Examples of the other copolymerizable monomers include functional group-containing monomers such as carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, acrylamide, and acrylonitrile. Examples of the carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of the hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of glycidyl group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of acrylamides include N-acryloylmorpholine. These may be used alone or in combination of two or more. The content of the structural units derived from the copolymerizable monomers is preferably 60 parts by weight or less, more preferably 40 parts by weight or less, per 100 parts by weight of the base polymer.

[0035] The acrylic polymer may contain structural units derived from polyfunctional monomers to form crosslinked structures in the polymer backbone. Examples of polyfunctional monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate (i.e., polyglycidyl (meth)acrylate), polyester (meth)acrylate, and urethane (meth)acrylate. These may be used alone or in combination of two or more. The content of the structural units derived from the polyfunctional monomer is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, per 100 parts by weight of the base polymer.

[0036] The weight-average molecular weight of the acrylic polymer is preferably 100,000 to 3,000,000, and more preferably 200,000 to 2,000,000. The weight-average molecular weight can be measured by GPC (solvent: THF).

[0037] Examples of the active energy ray reactive compound that can be used in the pressure-sensitive adhesive (A1) include photoreactive monomers or oligomers having a functional group with a polymerizable carbon-carbon multiple bond, such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, or an acetylene group. Specific examples of the photoreactive monomer include esters of (meth)acrylic acid and polyhydric alcohols such as trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; polyfunctional urethane (meth)acrylate; epoxy (meth)acrylate; oligoester (meth)acrylate; etc. Also usable are monomers such as methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Specific examples of the photoreactive oligomer include dimers to pentamers of the above-mentioned monomers. The molecular weight of the photoreactive oligomer is preferably 100 to 3,000.

[0038] Furthermore, as the active energy ray reactive compound, a monomer such as epoxidized butadiene, glycidyl methacrylate, acrylamide, vinyl siloxane, or the like, or an oligomer composed of such a monomer may be used.

[0039] Furthermore, the active energy ray-reactive compound may be a mixture of an organic salt such as an onium salt and a compound having multiple heterocycles in the molecule. When the mixture is irradiated with active energy rays (e.g., ultraviolet light or an electron beam), the organic salt is cleaved to generate ions, which act as initiating species to cause a ring-opening reaction of the heterocycles, forming a three-dimensional network structure. Examples of the organic salt include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocycle in the compound having multiple heterocycles in the molecule include oxirane, oxetane, oxolane, thiirane, and aziridine.

[0040] In the pressure-sensitive adhesive (A1), the content of the active energy ray-reactive compound is preferably 0.1 to 500 parts by weight, more preferably 5 to 300 parts by weight, and even more preferably 40 to 150 parts by weight, relative to 100 parts by weight of the base polymer.

[0041] Examples of the active energy ray-reactive polymer (base polymer) contained in the pressure-sensitive adhesive (A2) include polymers having functional groups with carbon-carbon multiple bonds such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, acetylene groups, etc. Specific examples of the active energy ray-reactive polymer include polymers composed of multifunctional (meth)acrylates, photocationic polymerizable polymers, cinnamoyl group-containing polymers such as polyvinyl cinnamate, diazotized amino novolac resins, polyacrylamides, etc.

[0042] In one embodiment, an active energy ray-reactive polymer is used, which is constructed by introducing an active energy ray-polymerizable carbon-carbon multiple bond into the side chain, main chain, and / or main chain terminal of the acrylic polymer. A method for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer includes, for example, copolymerizing raw material monomers including a monomer having a predetermined functional group (first functional group) to obtain an acrylic polymer, and then subjecting a compound having a radiation-polymerizable carbon-carbon double bond and a predetermined functional group (second functional group) capable of reacting with and bonding to the first functional group to a condensation reaction or addition reaction with the acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond.

[0043] Examples of combinations of the first functional group and the second functional group include a carboxyl group and an epoxy group, an epoxy group and a carboxyl group, a carboxyl group and an aziridyl group, an aziridyl group and a carboxyl group, a hydroxyl group and an isocyanate group, and an isocyanate group and a hydroxyl group. Among these combinations, a hydroxyl group and an isocyanate group, or an isocyanate group and a hydroxyl group, is preferred from the viewpoint of ease of reaction tracking. Furthermore, while producing a polymer having a highly reactive isocyanate group is technically difficult, from the viewpoint of ease of production or availability of the acrylic polymer, it is more preferred that the first functional group on the acrylic polymer be a hydroxyl group and the second functional group be an isocyanate group. In this case, examples of isocyanate compounds having both a radiation-polymerizable carbon-carbon double bond and an isocyanate group as the second functional group include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, the acrylic polymer having a first functional group is preferably one that contains a structural unit derived from the above-mentioned hydroxy group-containing monomer, and is also preferably one that contains a structural unit derived from an ether compound such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, or diethylene glycol monovinyl ether.

[0044] The pressure-sensitive adhesive (A2) may further contain the active energy ray-reactive compound (monomer or oligomer).

[0045] The active energy ray-curable pressure-sensitive adhesive may contain an ultraviolet absorber and / or a photopolymerization initiator. The ultraviolet absorber and photopolymerization initiator to be used will be described in detail below.

[0046] In one embodiment, the active energy ray-curable pressure-sensitive adhesive may contain a photosensitizer. Examples of photosensitizers include "UVS-581" manufactured by Kawasaki Chemical Industries, Ltd., and 9,10-diethoxyanthracene (e.g., "UVS-1101" manufactured by Kawasaki Chemical Industries, Ltd.). Other examples of the photosensitizer include 9,10-dibutoxyanthracene (e.g., "UVS-1331" manufactured by Kawasaki Chemical Industries, Ltd.), 2-isopropylthioxanthone, benzophenone, thioxanthone derivatives, and 4,4'-bis(dimethylamino)benzophenone. Examples of thioxanthone derivatives include ethoxycarbonylthioxanthone and isopropylthioxanthone.

[0047] The content of the photosensitizer is preferably 0.01 to 2 parts by weight, and more preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the base polymer.

[0048] Preferably, the active energy ray-curable pressure-sensitive adhesive contains a crosslinking agent, such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, or an amine-based crosslinking agent.

[0049] The content of the crosslinking agent is preferably 0.5 to 10 parts by weight, and more preferably 1 to 8 parts by weight, relative to 100 parts by weight of the base polymer of the pressure-sensitive adhesive.

[0050] In one embodiment, an isocyanate-based crosslinking agent is preferably used, which is preferred because it can react with a variety of functional groups. Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), and hexamethylene diisocyanate isocyanurate (manufactured by Tosoh Corporation, trade name "Coronate HX"). Preferably, a crosslinking agent having three or more isocyanate groups is used.

[0051] The active energy ray-curable pressure-sensitive adhesive may further contain any appropriate additives as necessary, such as an active energy ray polymerization accelerator, a radical scavenger, a coupling agent (e.g., a silane coupling agent), a tackifier, a plasticizer (e.g., a trimellitic acid ester-based plasticizer, a pyromellitic acid ester-based plasticizer, etc.), a pigment, a dye, a filler, an antioxidant, a conductive material, an antistatic agent, a light stabilizer, a release adjuster, a softener, a surfactant, a flame retardant, an antioxidant, particles, and an ultraviolet absorber.

[0052] (Photopolymerization initiator) Any suitable initiator can be used as the photopolymerization initiator. Examples of the photopolymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. Examples of suitable photopolymerization initiators include aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride, photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime, benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone, camphorquinone, halogenated ketones, acylphosphinoxides, and acylphosphonates. The amount of the photopolymerization initiator used can be set to any appropriate amount.

[0053] In one embodiment, a photopolymerization initiator having a maximum absorption wavelength in the range of 400 nm or less (preferably 380 nm or less, more preferably 340 nm or less) is used.

[0054] The amount of the photopolymerization initiator used can be set to any appropriate amount.

[0055] The photopolymerization initiator may be a commercially available product. For example, examples of photopolymerization initiators having a maximum absorption wavelength in the range of 400 nm or less include those under the trade names "Irgacure 127," "Irgacure 369," "Irgacure 369E," "Irgacure 379," "Irgacure 379EG," "Irgacure 819," "Irgacure TOP," "Irgacure 784," and "Irgacure OXE01," manufactured by BASF.

[0056] C.Adhesive layer The thickness of the pressure-sensitive adhesive layer is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. Within such a range, the above-mentioned effects become significant. The lower limit of the pressure-sensitive adhesive layer thickness is, for example, 1 μm (preferably 0.5 μm).

[0057] The pressure-sensitive adhesive layer has an indentation modulus I at 23°C of preferably 0.05 MPa to 20 MPa, more preferably 0.08 MPa to 10 MPa, and even more preferably 0.08 MPa to 5 MPa. Within this range, it is possible to optimize the deformation of each layer due to laser light irradiation and obtain a pressure-sensitive adhesive sheet that has excellent releasability due to laser light irradiation. Such a pressure-sensitive adhesive sheet can achieve reliable releasability within a narrow range.

[0058] The pressure-sensitive adhesive layer preferably has a light transmittance of 50% or less at a wavelength of 248 nm, more preferably 30% or less, even more preferably 10% or less, and particularly preferably 5% or less. The lower the light transmittance of the pressure-sensitive adhesive layer at a wavelength of 248 nm, the better, and the lower limit is, for example, 0.5% (preferably 0%).

[0059] The pressure-sensitive adhesive layer preferably has a light transmittance of 50% or more at a wavelength of 365 nm, more preferably 60% or more, and even more preferably 70% or more. The higher the light transmittance of the pressure-sensitive adhesive layer at a wavelength of 365 nm, the better, and the upper limit is, for example, 95% (preferably 100%).

[0060] The haze value of the pressure-sensitive adhesive sheet of the pressure-sensitive adhesive layer is preferably 70% or less, more preferably 65% ​​or less. In one embodiment, the haze value of the pressure-sensitive adhesive layer is 20% or less. The lower the haze value of the pressure-sensitive adhesive layer, the better, and the lower limit is, for example, 0.1%.

[0061] The pressure-sensitive adhesive layer includes any suitable pressure-sensitive adhesive. Any suitable pressure-sensitive adhesive can be used as the pressure-sensitive adhesive as long as the effects of the present invention can be obtained. For example, a pressure-sensitive adhesive can be used as the pressure-sensitive adhesive.

[0062] (pressure-sensitive adhesive) Examples of pressure-sensitive adhesives include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and styrene-diene block copolymer adhesives. Among these, acrylic adhesives or rubber adhesives are preferred, and acrylic adhesives are even more preferred. The above adhesives may be used alone or in combination of two or more. In one embodiment, from the viewpoint of ultraviolet absorption, an adhesive containing a base polymer having an aromatic ring and / or a double bond is used. From this perspective, acrylic adhesives are also preferred.

[0063] Examples of the acrylic adhesive include an acrylic adhesive having as a base polymer an acrylic polymer (homopolymer or copolymer) using one or more (meth)acrylic acid alkyl esters as a monomer component. Specific examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and methyl (meth)acrylate. Examples of (meth)acrylic acid C1-20 alkyl esters include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms can be preferably used.

[0064] The acrylic polymer may contain, as necessary, units corresponding to other monomer components copolymerizable with the alkyl (meth)acrylate, for the purpose of modifying properties such as cohesive strength, heat resistance, and crosslinkability. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itanoic anhydride; hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; (N-substituted) amide monomers such as methylol (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylol propane (meth) acrylamide; aminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; maleimide monomers such as N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, and N-phenyl maleimide; itaconimide monomers such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide, and N-lauryl itaconimide;succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; vinyl-based monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and (meth)acrylate. Examples of suitable monomers include glycol-based acrylic ester monomers such as methoxypolypropylene glycol acrylate; acrylic ester monomers having heterocycles, halogen atoms, silicon atoms, etc., such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; polyfunctional monomers such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; olefin-based monomers such as isoprene, butadiene, and isobutylene; and vinyl ether-based monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more.

[0065] Examples of the rubber-based pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives whose base polymer is natural rubber; polyisoprene rubber, styrene-butadiene (SB) rubber, styrene-isoprene (SI) rubber, styrene-isoprene-styrene block copolymer (SIS) rubber, styrene-butadiene-styrene block copolymer (SBS) rubber, styrene-ethylene-butylene-styrene block copolymer (SEBS) rubber, styrene-ethylene-propylene-styrene block copolymer (SEPS) rubber, styrene-ethylene-propylene block copolymer (SEP) rubber, reclaimed rubber, butyl rubber, polyisobutylene, and synthetic rubbers such as modified versions of these.

[0066] The pressure-sensitive adhesive may contain any suitable additives as needed, such as crosslinkers, tackifiers (e.g., rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, etc.), plasticizers (e.g., trimellitic ester-based plasticizers, pyromellitic ester-based plasticizers), pigments, dyes, antioxidants, conductive materials, antistatic agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, ultraviolet absorbers, particles, etc.

[0067] Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred. In one embodiment, from the viewpoint of ultraviolet absorption, a crosslinking agent having an aromatic ring and / or a double bond (e.g., an aromatic isocyanate-based crosslinking agent) is used.

[0068] Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), and hexamethylene diisocyanate isocyanurate (manufactured by Tosoh Corporation, trade name "Coronate HX"). The content of the isocyanate-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer.

[0069] Examples of the epoxy crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500NP"), and ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500NP"). Licor diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol E-400"), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol") Examples of suitable crosslinking agents include glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy crosslinking agent can be set at any appropriate amount depending on the desired adhesive strength, and is typically 0.01 to 10 parts by weight, and more preferably 0.03 to 5 parts by weight, per 100 parts by weight of the base polymer.

[0070] Examples of the tackifier include rosin-based resins (e.g., rosin ester resins), terpene-based resins (e.g., terpene-phenol copolymers (terpene-modified phenolic resins), hydrogenated terpene resins), coumarone-indene resins, alicyclic saturated hydrocarbon-based resins, petroleum-based resins (e.g., hydrocarbon-based petroleum resins such as aliphatic / aromatic copolymer petroleum resins and aromatic petroleum resins), and phenol-based resins. In one embodiment, from the viewpoint of ultraviolet absorption, a crosslinker having an aromatic ring and / or a double bond (e.g., rosin-based resin) is used. The content of the tackifier can be set to any appropriate amount depending on the desired adhesive strength, and is typically 1 to 50 parts by weight, and more preferably 10 to 30 parts by weight, per 100 parts by weight of the base polymer.

[0071] D. Base material The substrate may be made of any suitable resin. Examples of the resin include polyolefin resins such as polyethylene resins, polypropylene resins, polybutene resins, and polymethylpentene resins, polyurethane resins, polyester resins, polyimide resins, polyether ketone resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicone resins, cellulose resins, and ionomer resins. Among these, polyolefin resins are preferred.

[0072] In one embodiment, the substrate is made of at least one resin selected from the group consisting of polyethylene terephthalate resin, polyimide resin, polystyrene resin, and polycarbonate resin. Substrates made of these resins are advantageous in that they have low transmittance at a wavelength of 248 nm.

[0073] The thickness of the substrate is preferably 2 μm to 300 μm, more preferably 2 μm to 100 μm, and even more preferably 2 μm to 50 μm. In one embodiment, the thickness of the substrate is less than 50 μm, more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. By reducing the thickness of the substrate, strain generated in the pressure-sensitive adhesive layer is easily propagated to the transfer layer, and a pressure-sensitive adhesive sheet with excellent releasability can be obtained.

[0074] The indentation modulus of the substrate at 23°C is preferably 5000 MPa or less, more preferably 3000 MPa or less, and even more preferably 1000 MPa or less. Within this range, the substrate is less likely to absorb strain generated in the pressure-sensitive adhesive layer and is more likely to propagate strain to the transfer layer. The lower limit of the indentation modulus of the substrate at 23°C is preferably 1 MPa, more preferably 5 MPa, and even more preferably 10 MPa. Within this range, a pressure-sensitive adhesive sheet having appropriate rigidity and excellent handleability can be obtained.

[0075] The total light transmittance of the substrate is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. The upper limit of the total light transmittance of the substrate is, for example, 98% (preferably 99%).

[0076] E. Manufacturing method of adhesive sheet The PSA sheet can be produced by any appropriate method. The PSA sheet can be obtained, for example, by coating a substrate or a release liner with the PSA that forms the PSA layer and the transfer layer. Various coating methods can be used, including bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, and screen printing. Alternatively, a PSA sheet can be formed by forming a PSA layer on a release liner, forming a transfer layer on another release liner, and laminating these together, or by laminating these together to a substrate.

[0077] F. How to use the adhesive sheet The pressure-sensitive adhesive sheet of the present invention can be used to temporarily fix any suitable workpiece (e.g., electronic components) during processing and / or transport. Examples of methods for using the pressure-sensitive adhesive sheet of the present invention include (i) attaching the pressure-sensitive adhesive layer to a support, (ii) attaching and fixing the workpiece to the transfer layer of the attachment sheet, (ii) processing or transporting the workpiece, (iii) irradiating the pressure-sensitive adhesive sheet with active energy rays (e.g., ultraviolet rays) to reduce the adhesive strength of the transfer layer side of the pressure-sensitive adhesive sheet, and (iv) irradiating the desired area for release with laser light to cause distortion in the pressure-sensitive adhesive layer. This method allows the workpiece to be peeled by natural drop. Furthermore, when multiple workpieces are temporarily fixed, it is also possible to peel only a portion of them. By using the pressure-sensitive adhesive sheet of the present invention, the adhesive strength can be reduced to the point where the workpiece can be released by natural drop, making it possible to peel even very small workpieces (e.g., 50 μm square) individually.

[0078] The support in (i) may be, for example, a glass plate. The support is preferably light-transmitting. The total light transmittance of the support is, for example, 50% or more, preferably 80% or more.

[0079] In one embodiment, the active energy rays in (iii) above are applied from the pressure-sensitive adhesive layer side (substantially, the support side) of the pressure-sensitive adhesive sheet.

[0080] In one embodiment, the laser light in (iv) above is applied from the pressure-sensitive adhesive layer side (substantially, the support side) of the pressure-sensitive adhesive sheet.

[0081] In one embodiment, the wavelength of the laser light is 200 nm to 300 nm. [Example]

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Test and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" are by weight.

[0083] (1) Adhesion strength of adhesive layer to glass I The PET separator on the transfer layer side of the pressure-sensitive adhesive sheet was peeled off, and a 25 μm-thick PET (Lumirror S10 manufactured by Toray Industries, Inc.) was laminated. The PET separator on the other side was then peeled off, and the sheet was laminated to a glass plate (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200423") using a 2 kg roller in one stroke. The adhesive strength was measured according to JIS Z 0237:2000 (peel angle 180°, peel speed (tensile speed) 300 mm / min, measurement temperature: 23°C).

[0084] (2) Adhesion of the transfer layer to the stainless steel plate The PET separator on the adhesive layer side of the adhesive sheet (in Comparative Example 2, one of the PET separators attached to the transfer layer) was peeled off, and a 25 μm thick PET sheet (Lumirror S10 manufactured by Toray Industries, Inc.) was attached. The PET separator on the other side was then peeled off, and the sheet was attached to SUS304 using a 2 kg roller going back and forth once. The adhesive strength was measured using a method in accordance with JIS Z 0237:2000 (peel angle 180°, peel speed (tensile speed) 300 mm / min, measurement temperature: 23°C), and this was taken as initial adhesive strength A. After adhering the adhesive sheet to the SUS304 in the same way, the adhesive layer was exposed to ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, cumulative light intensity: 300 mJ / cm ) using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810"). 2 ) was irradiated onto the entire surface, and the adhesive strength was measured in the same manner, and this was taken as adhesive strength B after curing.

[0085] (3) Indentation modulus (before curing) The indentation modulus of the pressure-sensitive adhesive layer and the transfer layer was measured using a Tripoint Indenter TI-950 manufactured by Hysitron Corp. The measurement was performed at 23°C by the single indentation method at an indentation speed of 10 nm / s and an indentation depth of 100 nm.

[0086] (4) Indentation modulus (after curing) The PET separator on the adhesive layer side of the adhesive sheet (in Comparative Example 2, one of the PET separators attached to the transfer layer) was peeled off, and the sheet was attached to a large glass slide (manufactured by Matsunami Glass, product name "S9111") using a hand roller. The glass slide side of the obtained sample was irradiated with ultraviolet light (specific wavelength: 365 nm, cumulative light intensity: 300 mJ / cm) from a high-pressure mercury lamp using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810"). 2 The entire surface was irradiated with UV light. The other PET separator was then peeled off to expose the transfer layer, and the indentation modulus was measured using a Hysitron Tri-Point Indenter TI-950. Measurements were performed at 23°C using the single indentation method, with an indentation speed of 10 nm / s and an indentation depth of 100 nm.

[0087] (5) Haze value The haze value of the pressure-sensitive adhesive sheet was measured using a haze meter (trade name "HAZE METER HM-150", manufactured by Murakami Color Research Laboratory).

[0088] (6) Light transmittance The light transmittance of the pressure-sensitive adhesive sheet at wavelengths of 365 nm and 248 nm was measured using a spectrophotometer (trade name "Spectrophotometer U-4100", manufactured by Hitachi High-Tech Science).

[0089] (7) Peelability (transferability) The PET separator on the adhesive layer side of the adhesive sheet (in Comparative Example 2, one of the PET separators attached to the transfer layer) was peeled off, and the sheet was attached to a quartz plate (manufactured by AS ONE Corporation) using a hand roller. Then, the PET separator on the other side was peeled off, and a 125 μm × 100 μm silicon chip was attached to the adhesive surface of the transfer layer. Using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810") from the quartz plate side, ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, cumulative light intensity: 300 mJ / cm 2 ) was irradiated over the entire surface. Then, a laser beam with a wavelength of 248 nm (irradiation area: 130 μm × 105 μm, output: 100 mJ / cm) 2 ), and irradiated only at the target component position from the quartz plate side (1 plus per chip). If the component fell naturally, it was judged as passing (◯), and if it did not fall naturally, it was judged as failing (×).

[0090] (8) Presence or absence of deformation The deformation of the transfer layer surface after laser irradiation was observed under a microscope. If a significant color difference was observed between the laser irradiated area and other areas, it was judged as failing (×), and if not, it was judged as passing (◯). FIG. 2(a) shows a micrograph of the transfer layer surface in Example 1 (deformation evaluation: passed), and FIG. 2(b) shows a micrograph of the transfer layer surface in Comparative Example 1 (deformation evaluation: failed).

[0091] (9) Adhesive residue The glass plate after evaluation of "(1) Adhesion strength of the adhesive layer to the glass" was visually inspected. If the adhesive layer remained on the glass, it was evaluated as "fail" (×), and if not, it was evaluated as "pass" (◯).

[0092] [Production Example 1] Preparation of Acrylic Polymer I A monomer composition was prepared by mixing 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid, and 1 part by weight of 4-hydroxybutyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 103.1 parts by weight of the above monomer composition, 0.2 parts by weight of benzoyl peroxide (BPO), and 150 parts by weight of toluene were charged and stirred at 60°C for 6 hours to obtain an acrylic polymer solution I containing an acrylic polymer I.

[0093] [Production Example 2] Preparation of Acrylic Polymer II A monomer composition was prepared by mixing 70 parts by weight of ethyl acrylate, 30 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of methyl methacrylate acrylate, and 4 parts by weight of hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 295 parts by weight of toluene, 109 parts by weight of the above monomer composition, and 0.2 parts by weight of benzoyl peroxide (BPO) were charged and stirred at 60°C for 4 hours to obtain an acrylic polymer solution II containing an acrylic polymer II having a weight-average molecular weight of 500,000.

[0094] [Production Example 3] Preparation of Acrylic Polymer III A monomer composition was prepared by mixing 100 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of acrylic acid, and 0.01 parts by weight of trimethylolpropane triacrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 102.01 parts by weight of the above monomer composition, 0.2 parts by weight of benzoyl peroxide (BPO), and 189 parts by weight of toluene were charged and stirred at 60°C for 7 hours to obtain an acrylic polymer solution III containing an acrylic polymer III.

[0095] [Production Example 4] Preparation of Acrylic Polymer IV A monomer composition was prepared by mixing 100 parts by weight of butyl acrylate, 78 parts by weight of ethyl acrylate, and 40 parts by weight of hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 507 parts by weight of toluene, 218 parts by weight of the monomer composition, and 1.2 parts by weight of benzoyl peroxide (BPO) were charged and stirred for 5 hours at 60° C. Thereafter, the mixture was cooled to room temperature, and 42.6 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, yielding an acrylic polymer solution IV containing an acrylic polymer IV having a terminal carbon-carbon double bond.

[0096] [Production Example 5] Preparation of Acrylic Polymer V A monomer composition was prepared by mixing 100 parts by weight of 2-ethylhexyl acrylate, 25.5 parts by weight of acryloylmorpholine, and 18.5 parts by weight of hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 60 parts by weight of toluene, 144 parts by weight of the monomer composition, and 0.3 parts by weight of benzoyl peroxide (BPO) were charged and stirred for 4 hours at 60° C. Thereafter, the mixture was cooled to room temperature, and 12 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, yielding an acrylic polymer solution V containing an acrylic polymer V having a terminal carbon-carbon double bond.

[0097] [Production Example 6] Preparation of acrylic polymer VI A monomer composition was prepared by mixing 100 parts by weight of 2-methoxyethyl acrylate, 27 parts by weight of acryloylmorpholine, and 22 parts by weight of 2-hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 500 parts by weight of toluene, 149 parts by weight of the monomer composition, and 0.3 parts by weight of benzoyl peroxide (BPO) were charged and stirred for 5 hours at 60° C. Thereafter, the mixture was cooled to room temperature, and 24 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, yielding an acrylic polymer solution VI containing an acrylic polymer VI having a terminal carbon-carbon double bond.

[0098] [Example 1] (Preparation of adhesive) To an acrylic polymer solution I containing 100 parts by weight of acrylic polymer I, 2 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L") and 30 parts by weight of a tackifying resin (manufactured by Arakawa Chemical Industries, Ltd., product name "D-125") were added to obtain an adhesive (1) for forming an adhesive layer. To an acrylic polymer solution IV containing 100 parts by weight of acrylic polymer IV, 3 parts by weight of a crosslinker (manufactured by Tosoh Corporation, product name "Coronate L") and 10 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Irgacure 127") were added to obtain an adhesive (A) for forming a transfer layer. (adhesive sheet) The pressure-sensitive adhesive (1) was applied to the silicone-treated surface of a PET separator (thickness: 38 μm), and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 4 μm. Separately, the pressure-sensitive adhesive (A) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. An adhesive layer with a PET separator was bonded to one side of a PET substrate (manufactured by Toray Industries, Inc., product name "Lumirror 2DC61", thickness: 2 μm), and a transfer layer with a PET separator was bonded to the other side, to obtain an adhesive sheet consisting of PET separator / adhesive layer / substrate / transfer layer / PET separator. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0099] [Example 2] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that acrylic polymer solution V containing 100 parts by weight of acrylic polymer V was used instead of acrylic polymer solution IV. The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0100] [Example 3] To an acrylic polymer solution VI containing 100 parts by weight of acrylic polymer VI, 5 parts by weight of a crosslinker (manufactured by Tosoh Corporation, product name "Coronate L") and 10 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Irgacure 127") were added to obtain an adhesive (C) for forming a transfer layer. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the transfer layer was formed using pressure-sensitive adhesive (C) instead of pressure-sensitive adhesive (A). The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0101] [Example 4] To an acrylic polymer solution VI containing 100 parts by weight of acrylic polymer VI, 5 parts by weight of a crosslinker (manufactured by Tosoh Corporation, product name "Coronate L"), 10 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Irgacure 127"), and 5 parts by weight of silica microparticles (manufactured by Admatechs, product name "YA050C") were added to obtain an adhesive (D) for forming a transfer layer. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the transfer layer was formed using pressure-sensitive adhesive (D) instead of pressure-sensitive adhesive (A). The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0102] [Example 5] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that the thickness of the pressure-sensitive adhesive layer was set to 20 μm. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0103] [Example 6] (Preparation of adhesive) In the same manner as in Example 1, a pressure-sensitive adhesive (1) for forming a pressure-sensitive adhesive layer was obtained. To an acrylic polymer solution VI containing 100 parts by weight of acrylic polymer VI, 5 parts by weight of a crosslinker (manufactured by Tosoh Corporation, trade name "Coronate L"), 10 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 127"), and 5 parts by weight of an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin 405", molecular weight: 583.8) were added to obtain an adhesive (E) for forming a transfer layer. (adhesive sheet) The pressure-sensitive adhesive (1) was applied to the silicone-treated surface of a PET separator (thickness: 38 μm), and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 4 μm. Separately, the pressure-sensitive adhesive (E) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. An adhesive layer with a PET separator was bonded to one side of a PET substrate (manufactured by Toray Industries, Inc., product name "Lumirror S10", thickness: 25 μm), and a transfer layer with a PET separator was bonded to the other side, to obtain an adhesive sheet consisting of PET separator / adhesive layer / substrate / transfer layer / PET separator. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0104] [Example 7] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that the thickness of the transfer layer was 25 μm. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0105] [Example 8] (Preparation of adhesive) 8.5 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L") was added to acrylic polymer solution II containing 100 parts by weight of acrylic polymer II to obtain adhesive (2) for forming an adhesive layer. In the same manner as in Example 3, a pressure-sensitive adhesive (C) for forming a transfer layer was obtained. (adhesive sheet) The pressure-sensitive adhesive (2) was applied to the silicone-treated surface of a PET separator (thickness: 38 μm), and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 4 μm. Separately, the pressure-sensitive adhesive (C) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. An adhesive layer with a PET separator was bonded to one side of a PET substrate (manufactured by Toray Industries, Inc., product name "Lumirror 2DC61", thickness: 2 μm), and a transfer layer with a PET separator was bonded to the other side, to obtain an adhesive sheet consisting of PET separator / adhesive layer / substrate / transfer layer / PET separator. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0106] [Comparative Example 1] (Preparation of adhesive) To an acrylic polymer solution III containing 100 parts by weight of acrylic polymer III, 2 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L") was added to obtain an adhesive (3) for forming an adhesive layer. In the same manner as in Example 3, a pressure-sensitive adhesive (C) for forming a transfer layer was obtained. (adhesive sheet) The pressure-sensitive adhesive (3) was applied to the silicone-treated surface of a PET separator (thickness: 38 μm), and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 4 μm. Separately, the pressure-sensitive adhesive (C) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. An adhesive layer with a PET separator was bonded to one side of a PET substrate (manufactured by Toray Industries, Inc., product name "Lumirror 2DC61", thickness: 2 μm), and a transfer layer with a PET separator was bonded to the other side, to obtain an adhesive sheet consisting of PET separator / adhesive layer / substrate / transfer layer / PET separator. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0107] Comparative Example 2 (Preparation of adhesive) In the same manner as in Example 3, a pressure-sensitive adhesive (C) for forming a transfer layer was obtained. (adhesive sheet) The pressure-sensitive adhesive (C) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. Another PET separator (thickness: 38 μm) was laminated on the transfer layer to obtain a pressure-sensitive adhesive sheet consisting of PET separator / transfer layer / PET separator.

[0108] Comparative Example 3 To acrylic polymer solution I containing 100 parts by weight of acrylic polymer I, 2 parts by weight of a crosslinker (manufactured by Tosoh Corporation, product name "Coronate L") and 30 parts by weight of a tackifying resin (manufactured by Arakawa Chemical Industries, Ltd., product name "D-125") were added to obtain adhesive (F) for forming a transfer layer. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the transfer layer was formed using pressure-sensitive adhesive (F) instead of pressure-sensitive adhesive (A). The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0109] Comparative Example 4 To an acrylic polymer solution V containing 100 parts by weight of acrylic polymer V, 3 parts by weight of a crosslinker (manufactured by Tosoh Corporation, product name "Coronate L") and 0.5 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Irgacure 127") were added to obtain an adhesive (G) for forming a transfer layer. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 8, except that the transfer layer was formed using pressure-sensitive adhesive (G) instead of pressure-sensitive adhesive (C). The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[0110] Comparative Example 5 (Preparation of adhesive) In the same manner as in Example 1, a pressure-sensitive adhesive (1) for forming a pressure-sensitive adhesive layer was obtained. In the same manner as in Comparative Example 3, a pressure-sensitive adhesive (F) for forming a transfer layer was obtained. (adhesive sheet) The pressure-sensitive adhesive (1) was applied to the silicone-treated surface of a PET separator (thickness: 38 μm), and then heated at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 4 μm. Separately, the pressure-sensitive adhesive (F) was applied to the silicone-treated surface of a PET separator (thickness: 75 μm), and then heated at 120° C. for 2 minutes to form a transfer layer with a thickness of 5 μm. An adhesive layer with a PET separator was bonded to one side of a PET substrate (manufactured by Toray Industries, Inc., product name "Lumirror S27", thickness: 75 μm), and a transfer layer with a PET separator was bonded to the other side, to obtain an adhesive sheet consisting of PET separator / adhesive layer / substrate / transfer layer / PET separator. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0111] Comparative Example 6 An adhesive sheet was obtained in the same manner as in Comparative Example 5, except that a PP substrate (manufactured by Toray Industries, Inc., product name "Lumirror S27", thickness: 75 μm) was used instead of the PET substrate (manufactured by Toray Industries, Inc., product name "Torayfan BO 12D-KW37", thickness: 12 μm). The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0112] [Table 1] [Explanation of symbols]

[0113] 10 adhesive layer 20 Transfer layer 30 Base material 100, 200 adhesive sheets

Claims

1. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, a substrate, and a transfer layer in this order, the transfer layer contains an active energy ray-curable pressure-sensitive adhesive, the adhesive strength I at 23°C when the adhesive layer of the pressure-sensitive adhesive sheet is attached to a glass plate is 2 N / 20 mm or more; When the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to a glass plate, the adhesive strength I at 23°C is 300 mJ / cm ２ the ratio of the adhesive strength B of the transfer layer to the stainless steel plate at 23°C after irradiation with ultraviolet light is 5 or more, the pressure-sensitive adhesive sheet has a light transmittance of 50% or less at a wavelength of 248 nm; the distance between the pressure-sensitive adhesive layer and the transfer layer is 10 μm or less; The active energy ray-curable pressure-sensitive adhesive contains, as a base polymer, an acrylic polymer having a terminal carbon-carbon double bond. Adhesive sheet.

2. 300 mJ / cm ２ 2. The pressure-sensitive adhesive sheet according to claim 1, wherein after irradiation with ultraviolet light of 1000 nm, the indentation modulus B of the transfer layer at 23°C is at least 5 times the indentation modulus I of the pressure-sensitive adhesive layer at 23°C.

3. The pressure-sensitive adhesive sheet according to claim 1 or 2, which is used to temporarily fix a member to a support, and after transporting and / or processing the member, peel the member from the support by irradiating it with laser light.

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