JP7748801B2 - adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

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 transport, 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 problems in terms of production costs. There is also the problem of damage to the component when irradiated with high-power laser light.

Patent Document 2 also describes a method in which multiple 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.

Patent No. 5875850 Patent No. 6053756

The present invention was made to solve the above-mentioned problems of the prior art, and its purpose is to provide an adhesive sheet that can temporarily and releasably fix an adherend, that exhibits releasability with low-power laser light, that eliminates the need for a step of cleaning the adherend after peeling, and that exhibits peeling over a narrow area.

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 wherein 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 ratio of the adhesive strength I at 23°C when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to a glass plate to the adhesive strength B at 23°C after irradiating the transfer layer with 300 mJ/ ^cm2 of ultraviolet rays is 5 or more.
In one embodiment, the pressure-sensitive adhesive sheet further includes a substrate between the pressure-sensitive adhesive layer and the transfer layer.
In one embodiment, after irradiation with 300 mJ/cm ² of 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 irradiation with laser light.

The present invention provides an adhesive sheet that can temporarily and releasably fix an adherend, exhibits releasability with low-power laser light, eliminates the need for a step of cleaning the adherend after peeling, and exhibits peeling over a narrow area.

1A is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. 1A is a micrograph of the surface of the transfer layer in Example 1, and FIG. 1B is a micrograph of the surface of the transfer layer in Comparative Example 1.

A. Overview of the Pressure-Sensitive Adhesive Sheet 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 layer, as long as the effects of the present invention are obtained.

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), and then peel the member from the support after transportation, processing, etc. During peeling, laser light is irradiated, allowing pinpoint peeling of only the member in the desired position.

The transfer layer is a layer that hardens when irradiated with active energy rays. More specifically, the transfer layer has adhesive properties for fixing an adherend, and is configured so that the adhesiveness decreases when the layer is hardened by irradiation with active energy rays. Even after hardening, it is preferable that the adhesive strength remains sufficient to fix the adherend (for example, adhesive strength sufficient to prevent the adherend from falling off). In one embodiment, the adhesive strength of the entire transfer layer decreases when irradiated 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.

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 generates partial strain in the pressure-sensitive adhesive layer (and in a configuration having a substrate, the substrate as well). This strain propagates to the transfer layer, temporarily changing the shape of the transfer layer surface (adhesion surface), 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 crosslinkers; and their amounts), 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 peelability due to strain propagation. In the present invention, the above-mentioned effects enable the release of the adhesive, eliminating the need for high-power laser light, eliminating the need for a post-release step of cleaning the adherend, and narrowing the area where release occurs. 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 returns to its original shape). This prevents problems such as unwanted detachment of the adherend in areas where release is not desired.

When the adhesive layer of the pressure-sensitive adhesive sheet is adhered to a glass plate, the adhesive strength I at 23°C is 2 N/20 mm or greater. Increasing this adhesive strength I allows for optimization of the deformation of each layer due to laser light irradiation, narrowing the range of areas where peeling occurs, and preventing problems such as unwanted detachment of the adherend in areas 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 significant. 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 in one stroke, and after leaving it at 23°C for 30 minutes, the adhesive sheet is peeled off at a peel angle of 180° and a peel speed (pulling rate) of 300 mm/min to measure.

The initial adhesive strength A at 23°C immediately after the transfer layer of the pressure-sensitive adhesive sheet is applied 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 holding an adherend well 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 applied to a stainless steel plate (arithmetic mean surface roughness Ra: 50±25 nm) using a 2 kg roller in one stroke, and the sheet is left to stand at 23°C for 30 minutes. After this, the adhesive sheet is peeled off at a peel angle of 180° and a peel speed (tensile speed) of 300 mm/min. The adhesive strength of the transfer layer changes when exposed to active energy rays and laser light, but in this specification, "initial adhesive strength" refers to the adhesive strength before exposure to active energy rays and laser light.

In one embodiment, the adhesive sheet has an adhesive strength B at 23°C (also referred to as post-curing adhesive strength B) after being attached to the stainless steel plate and irradiating the transfer layer with 300 mJ/ ^cm2 of ultraviolet light. The 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, an 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 irradiation is carried out, for example, by irradiating the transfer layer with ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, integrated light intensity: 300 mJ/ ^cm2 ) using an ultraviolet irradiation device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810"). The ultraviolet irradiation can be carried out from the adhesive layer side.

When the adhesive layer is adhered to glass, the ratio of the adhesive strength I at 23°C to the adhesive strength B of the transfer layer after curing (adhesive strength I/adhesive strength B after curing) is 5 or greater. In other words, in the above-described 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 described above, it is possible to optimize the deformation of each layer due to laser light irradiation and obtain an adhesive sheet with excellent releasability upon 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 greater, more preferably 20 or greater, and even more preferably 200 or greater. Within this range, the effects of the present invention are significant. 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. In other words, in the above-mentioned pressure-sensitive adhesive sheet, the post-curing adhesive strength B can be 0.0001 times or more the adhesive strength I.

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 with an excellent balance between adherend fixation and releasability can be obtained.

In the above-mentioned pressure-sensitive adhesive sheet, the anchoring strength at 23°C 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 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.

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 peel angle of 180°, and a peel speed (tensile speed) of 300 mm/min.

The optical transmittance of the pressure-sensitive adhesive sheet of the present invention at a wavelength of 248 nm 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 optical transmittance of the pressure-sensitive adhesive sheet at a wavelength of 248 nm can be controlled by the optical 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 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 optical transmittance promotes distortion of 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 low-output laser light, use of the pressure-sensitive adhesive sheet reduces damage to the adherend during peeling and prevents breakage of the adherend. A lower optical transmittance at a wavelength of 248 nm is preferable, with the lower limit being, for example, 0.5% (preferably 0%).

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 favorably cured by irradiation with active energy rays. The higher the pressure-sensitive adhesive sheet's light transmittance at a wavelength of 365 nm, the better, with the upper limit being, for example, 95% (preferably 100%).

The haze value of the pressure-sensitive adhesive sheet of the present invention is preferably 70% or less, and 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%.

The thickness of the adhesive sheet is preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm. In one embodiment, the thickness of the adhesive sheet is 30 μm or less. If the adhesive sheet is thin, strain generated in the adhesive layer is easily propagated to the transfer layer, resulting in an adhesive sheet with excellent releasability.

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 this range, strain generated in the pressure-sensitive adhesive layer is easily propagated to the transfer layer, making it possible to obtain a pressure-sensitive adhesive sheet with excellent releasability.

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-mentioned effects become prominent.

The initial indentation modulus A of the transfer layer at 23°C is preferably 0.1 MPa or more and less than 14 MPa, more preferably 0.1 MPa to 10 MPa, and even more preferably 0.2 MPa to 8 MPa. Within these ranges, a pressure-sensitive adhesive sheet with excellent fixation can be obtained. The indentation 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 when exposed to active energy rays and laser light, and in this specification, "initial indentation modulus A" refers to the adhesive strength before exposure to active energy rays and laser light.

The transfer layer is preferably a layer having an indentation modulus B (also referred to as post-curing modulus B) of 14 MPa or more at 23°C after irradiation with 300 mJ/ ^cm2 of ultraviolet light, more preferably 15 MPa or more, even more preferably 20 MPa or more, and particularly preferably 50 MPa or more. Within this range, a pressure-sensitive adhesive sheet with excellent peelability 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).

After irradiation with 300 mJ/ ^cm2 of ultraviolet light, the transfer layer preferably has an indentation modulus B at 23°C that is 20 times or more, more preferably 30 times or more, even more preferably 30 to 1000 times, and particularly preferably 50 to 200 times, of the initial indentation modulus A of the transfer layer at 23°C. Within such a range, a pressure-sensitive adhesive sheet having an excellent balance between adherend fixation and releasability can be obtained.

After irradiation with 300 mJ/ ^cm2 of ultraviolet light, the transfer layer preferably has an indentation modulus B at 23°C that is at least 5 times, more preferably at least 10 times, even more preferably 50 to 5,000 times, and particularly preferably 100 to 3,000 times, of the indentation modulus I at 23°C of the pressure-sensitive adhesive layer. Within this 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 exhibits excellent releasability due to laser light irradiation. Such a pressure-sensitive adhesive sheet can achieve reliable releasability within a narrow range.

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.

(Active energy ray curable adhesive)
In one embodiment, an active energy ray-curable pressure-sensitive adhesive (A1) is used as the active energy ray-curable pressure-sensitive adhesive, which includes a base polymer as a base material and an active energy ray-reactive compound (monomer or oligomer) that can bond to the base polymer. In another embodiment, an active energy ray-curable pressure-sensitive adhesive (A2) is used, which includes an active energy ray-reactive polymer as the base polymer. Preferably, the base polymer has a functional group that can react with a photopolymerization initiator. Examples of the functional group include a hydroxyl group and a carboxyl group.

Examples of base polymers used in the pressure-sensitive adhesive (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. Acrylic-based polymers are particularly preferred.

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 units derived from the hydrocarbon group-containing (meth)acrylic acid esters is preferably 40 parts by weight or more, and more preferably 60 parts by weight or more, per 100 parts by weight of the base polymer.

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 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 acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of 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 above 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.

Acrylic polymers may contain structural units derived from polyfunctional monomers to form crosslinked structures within 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 above polyfunctional monomers 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.

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).

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. Monomers such as methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate may also be used. Specific examples of photoreactive oligomers include dimers to pentamers of the above monomers. The molecular weight of the photoreactive oligomer is preferably 100 to 3,000.

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

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 irradiated with active energy rays (e.g., ultraviolet light or an electron beam), the organic salt in the mixture cleaves to generate ions, which act as initiating species to trigger 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 heterocycles in the compound having multiple heterocycles in the molecule include oxirane, oxetane, oxolane, thiirane, and aziridine.

In the above-mentioned 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, per 100 parts by weight of the base polymer.

The active energy ray-reactive polymer (base polymer) contained in the pressure-sensitive adhesive (A2) may be, for example, a polymer having a functional group with a 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 active energy ray-reactive polymers include polymers composed of multifunctional (meth)acrylates; photocationic polymerization polymers; cinnamoyl group-containing polymers such as polyvinyl cinnamate; diazotized amino novolac resins; polyacrylamides; and the like.

In one embodiment, an active energy ray-reactive polymer is used in which an active energy ray-polymerizable carbon-carbon multiple bond is introduced into the side chain, main chain, and/or main chain terminal of the acrylic polymer. One 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 the acrylic polymer to a condensation reaction or addition reaction with a compound having a radiation-polymerizable carbon-carbon double bond and a predetermined functional group (second functional group) that can react with and bond to the first functional group while maintaining the radiation polymerizability of the carbon-carbon double bond.

Examples of combinations of first and second functional groups include a carboxy group and an epoxy group, an epoxy group and a carboxy group, a carboxy group and an aziridyl group, an aziridyl group and a carboxy group, a hydroxy group and an isocyanate group, and an isocyanate group and a hydroxy group. Of these combinations, from the perspective of ease of reaction tracking, a combination of a hydroxy group and an isocyanate group, or a combination of an isocyanate group and a hydroxy group, is preferred. Furthermore, while producing a polymer containing a highly reactive isocyanate group is technically difficult, from the perspective of ease of production or acquisition of acrylic polymers, it is more preferred that the first functional group on the acrylic polymer be a hydroxy 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 a second functional group include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, acrylic polymers having a first functional group are preferably those containing structural units derived from the above-mentioned hydroxy group-containing monomers, and also preferably those containing structural units derived from ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

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

The active energy ray-curable adhesive may contain an ultraviolet absorber and/or a photopolymerization initiator. Details of the ultraviolet absorber and photopolymerization initiator used will be described later.

In one embodiment, the active energy ray-curable 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 photosensitizers include 9,10-dibutoxyanthracene (e.g., "UVS-1331" manufactured by Kawasaki Chemical Industries, Ltd.), 2-isopropylthioxanthone, benzophenone, thioxanthone derivatives, 4,4'-bis(dimethylamino)benzophenone, and the like. Examples of thioxanthone derivatives include ethoxycarbonylthioxanthone and isopropylthioxanthone.

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

Preferably, the active energy ray-curable adhesive contains a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-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, and amine-based crosslinking agents.

The content of the crosslinking agent is preferably 0.5 to 10 parts by weight, and more preferably 1 to 8 parts by weight, per 100 parts by weight of the base polymer of the adhesive.

In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a wide 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 isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX"). Preferably, a crosslinking agent having three or more isocyanate groups is used.

The active energy ray-curable adhesive may further contain any appropriate additives as needed. Examples of additives include active energy ray polymerization accelerators, radical scavengers, coupling agents (e.g., silane coupling agents), tackifiers, plasticizers (e.g., trimellitate ester-based plasticizers, pyromellitate ester-based plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, light stabilizers, release adjusters, softeners, surfactants, flame retardants, antioxidants, particles, and UV absorbers.

(Photopolymerization initiator)
Any appropriate 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. 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.

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

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

Commercially available photopolymerization initiators may be used. For example, photopolymerization initiators with a maximum absorption wavelength in the range of 400 nm or less include BASF products under the trade names "Irgacure 127," "Irgacure 369," "Irgacure 369E," "Irgacure 379," "Irgacure 379EG," "Irgacure 819," "Irgacure TOP," "Irgacure 784," and "Irgacure OXE01."

C. Pressure-sensitive 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).

The indentation modulus I of the pressure-sensitive adhesive layer at 23°C is 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 with excellent releasability due to laser light irradiation. Such a pressure-sensitive adhesive sheet can achieve reliable releasability within a narrow range.

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

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, with an upper limit of 95% (preferably 100%), for example.

The haze value of the pressure-sensitive adhesive sheet of the pressure-sensitive adhesive layer is preferably 70% or less, and 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%.

The adhesive layer contains any suitable adhesive. Any suitable adhesive may be used as long as the effects of the present invention are achieved. For example, a pressure-sensitive adhesive may be used as the adhesive.

(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-mentioned 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 may be preferably used.

Examples of the acrylic adhesive include those based on an acrylic polymer (homopolymer or copolymer) containing one or more (meth)acrylic acid alkyl esters as monomer components. Specific examples of (meth)acrylic acid alkyl esters 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 (meth) 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. Of these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms are preferred.

The above acrylic polymer may, if necessary, contain units corresponding to other monomer components copolymerizable with the above (meth)acrylic acid alkyl ester in order to modify its cohesive strength, heat resistance, crosslinkability, etc. 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; and 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 (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(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-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide vinylimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; vinyl 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 the like. p) Glycol-based acrylic ester monomers such as methoxypolypropylene glycol acrylate; acrylic ester-based 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.

Examples of the rubber-based adhesives include those based on 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.

The pressure-sensitive adhesive may contain any suitable additives as needed. Examples of such additives include crosslinkers, tackifiers (e.g., rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, etc.), plasticizers (e.g., trimellitate ester-based plasticizers, pyromellitate ester-based plasticizers), pigments, dyes, antioxidants, conductive materials, antistatic agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, UV absorbers, particles, etc.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, as well as 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 perspective 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.

Specific examples of the above-mentioned isocyanate-based crosslinking agents 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 amount of 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 base polymer.

Examples of the epoxy-based 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 Licor diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 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 "DENACOL EX-611," glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "DENACOL EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, 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 per 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.

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, a crosslinker having an aromatic ring and/or double bond (e.g., rosin-based resin) is used from the perspective of UV absorption. The amount of tackifier can be set at 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.

D. Substrate 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.

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

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 adhesive layer is more easily propagated to the transfer layer, making it possible to obtain an adhesive sheet with excellent releasability.

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 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 with appropriate rigidity and excellent handleability can be obtained.

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%).

E. Method for Producing Pressure-Sensitive Adhesive Sheets The pressure-sensitive adhesive sheet can be produced by any suitable method. For example, the pressure-sensitive adhesive sheet can be obtained by coating a substrate or a release liner with the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer and the transfer layer. Various coating methods can be used, such as 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 pressure-sensitive adhesive sheet can be formed by forming a pressure-sensitive adhesive layer on a release liner and a transfer layer on another release liner, and then laminating these together, or by laminating these together to a substrate.

F. Method of Use of the Pressure-Sensitive Adhesive Sheet The pressure-sensitive adhesive sheet of the present invention can be used to temporarily fix any suitable workpiece (e.g., electronic components) when processing and/or transporting the workpiece. 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 adhesive 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 properties 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 falls naturally, making it possible to peel even very small workpieces (e.g., 50 μm square) individually.

The support in (i) above may be, for example, a glass plate. It is preferable that the support be light-transmitting. The total light transmittance of the support is, for example, 50% or more, and preferably 80% or more.

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.

In one embodiment, the laser light in (iv) above is applied from the adhesive layer side of the adhesive sheet (substantially, the support side).

In one embodiment, the wavelength of the laser light is 200 nm to 300 nm.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples. The test and evaluation methods used in the examples are as follows. Unless otherwise specified, "parts" and "%" are by weight.

(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 reciprocating motion, and 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).

(2) Adhesion strength of transfer layer to 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 (Lumirror S10 manufactured by Toray Industries, Inc.) was laminated. Thereafter, the PET separator on the other side was peeled off, and the sheet was laminated to SUS304 by rolling a 2 kg roller back and forth once, and 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 designated as initial adhesive strength A.
Using the same method, an adhesive sheet was attached to SUS304, and then the entire surface was irradiated with ultraviolet light (specific wavelength: 365 nm, cumulative light intensity: 300 mJ/cm ² ) from a high-pressure mercury lamp using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810") from the adhesive layer side, and the adhesive strength was measured in the same way, and this was designated as adhesive strength B after curing.

(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 a single indentation method at an indentation speed of 10 nm/s and an indentation depth of 100 nm.

(4) Indentation modulus (after curing)
The PET separator on the adhesive layer side of the pressure-sensitive 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 entire surface of the glass slide side of the obtained sample was irradiated with ultraviolet light (specific wavelength: 365 nm, cumulative light intensity: 300 mJ/cm ² ) from a high-pressure mercury lamp using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810"). The other PET separator was then peeled off to expose the transfer layer, and the indentation modulus was measured using a Tripoint Indenter TI-950 manufactured by Hysitron. 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.

(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).

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

(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. Thereafter, 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"), ultraviolet rays from a high-pressure mercury lamp (specific wavelength: 365 nm, cumulative light intensity: 300 mJ/cm ² ) were irradiated onto the entire surface from the quartz plate side.
Thereafter, laser light with a wavelength of 248 nm (irradiation area: 130 μm × 105 μm, output 100 mJ/cm ² ) was irradiated only onto 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 (×).

(8) Presence or absence of deformation The deformation of the transfer layer surface after laser irradiation was observed using a microscope. If a significant color difference was observed between the laser irradiated area and other areas, it was judged as fail (×), and if not, it was judged as pass (◯).
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).

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

[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, thereby obtaining an acrylic polymer solution I containing an acrylic polymer I.

[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 monomer composition, and 0.2 parts by weight of benzoyl peroxide (BPO) were charged and stirred at 60°C for 4 hours, thereby obtaining an acrylic polymer solution II containing an acrylic polymer II having a weight-average molecular weight of 500,000.

[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 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.

[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 2-hydroxyethyl acrylate in the copolymer, thereby obtaining an acrylic polymer solution IV containing an acrylic polymer IV having a terminal carbon-carbon double bond.

[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 an NCO group to the terminal OH group of the side chain of 2-hydroxyethyl acrylate in the copolymer, thereby obtaining an acrylic polymer solution V containing an acrylic polymer V having a terminal carbon-carbon double bond.

[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 2-hydroxyethyl acrylate in the copolymer, thereby obtaining acrylic polymer solution VI containing acrylic polymer VI having a terminal carbon-carbon double bond.

[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 crosslinker (manufactured by Tosoh Corporation, product name "Coronate L") and 30 parts by weight of a tackifier resin (manufactured by Arakawa Chemical Industries, Ltd., product name "D-125") were added to obtain a pressure-sensitive adhesive (1) for forming a pressure-sensitive adhesive layer.
To an acrylic polymer solution IV containing 100 parts by weight of acrylic polymer IV, 3 parts by weight of a crosslinking agent (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.
A pressure-sensitive adhesive layer with a PET separator was bonded to one surface 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 surface, thereby obtaining a pressure-sensitive adhesive sheet consisting of PET separator/pressure-sensitive 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.

[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.

[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 the pressure-sensitive adhesive (C) instead of the pressure-sensitive adhesive (A). The obtained pressure-sensitive adhesive sheet was subjected to the above-mentioned evaluations. The results are shown in Table 1.

[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 fine particles (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.

[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.

[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, 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 an ultraviolet absorber (manufactured by BASF, product 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.
A pressure-sensitive adhesive layer with a PET separator was bonded to one surface 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 surface, thereby obtaining a pressure-sensitive adhesive sheet consisting of PET separator/pressure-sensitive 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.

[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.

[Example 8]
(Preparation of adhesive)
To acrylic polymer solution II containing 100 parts by weight of acrylic polymer II, 8.5 parts by weight of a crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L") was added 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.
A pressure-sensitive adhesive layer with a PET separator was bonded to one surface 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 surface, thereby obtaining a pressure-sensitive adhesive sheet consisting of PET separator/pressure-sensitive 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.

[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 a pressure-sensitive adhesive (3) for forming a pressure-sensitive 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.
A pressure-sensitive adhesive layer with a PET separator was bonded to one surface 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 surface, thereby obtaining a pressure-sensitive adhesive sheet consisting of PET separator/pressure-sensitive 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.

[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.

[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 tackifier resin (manufactured by Arakawa Chemical Industries, Ltd., product name "D-125") were added to obtain an 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.

[Comparative Example 4]
To an acrylic polymer solution V containing 100 parts by weight of acrylic polymer V, 3 parts by weight of a crosslinking agent (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.

[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.
A pressure-sensitive adhesive layer with a PET separator was bonded to one surface of a PET substrate (manufactured by Toray Industries, Inc., trade name "Lumirror S27", thickness: 75 μm), and a transfer layer with a PET separator was bonded to the other surface, thereby obtaining a pressure-sensitive adhesive sheet consisting of PET separator/pressure-sensitive 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.

[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., trade name "Lumirror S27", thickness: 75 μm) was used instead of the PET substrate (manufactured by Toray Industries, Inc., trade 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.

10 Pressure-sensitive adhesive layer 20 Transfer layer 30 Substrate 100, 200 Pressure-sensitive adhesive sheet

Claims (3)

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;
the ratio of adhesive strength I at 23°C when the adhesive layer of the adhesive sheet is attached to a glass plate to adhesive strength B of the transfer layer to a stainless steel plate at 23°C after irradiating the transfer layer with ultraviolet light of 300 mJ/ ^cm2 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. The pressure-sensitive adhesive sheet according to claim 1, wherein after irradiation with 300 mJ/ ^cm2 of ultraviolet light, 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. 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.