WO2023149023A1

WO2023149023A1 - Adhesive sheet

Info

Publication number: WO2023149023A1
Application number: PCT/JP2022/038941
Authority: WO
Inventors: みずほ千葉; 俊平田中; 元気越智
Original assignee: 日東電工株式会社
Priority date: 2022-02-02
Filing date: 2022-10-19
Publication date: 2023-08-10
Also published as: TW202344647A

Abstract

Provided is an adhesive sheet that can be used in transfer of electronic components, said adhesive sheet being capable of contributing to a reduction in production costs, achieving excellent positional accuracy of electronic components and excellent fixability and peelability of electronic components with respect to the adhesive sheet, and being capable of preventing contamination of electronic components and damage to electronic components.　The present invention provides an adhesive sheet including an adhesive layer composed of an active energy ray-curable adhesive, wherein: the active energy ray-curable adhesive contains an ultraviolet absorber and/or a photopolymerization initiator; the adhesive layer has an initial indentation modulus of 4 MPa or less at 23°C; the adhesive layer has an indentation modulus of 150 MPa or more at 23°C after being irradiated with ultraviolet rays of 460 mJ/cm²; and the adhesive sheet has a light transmittance of 50% or less at a wavelength of 355 nm.

Description

Adhesive sheet

The present invention relates to an adhesive sheet.

Conventionally, when an electronic component arranged on a predetermined member is transferred to another member, the electronic component is received with an adhesive sheet, and then the electronic component is transferred to another member. there is For example, when incorporating an LED chip into a device, the LED chip formed on the member is once transferred onto an adhesive sheet and received, and then the LED chip is transferred from the adhesive sheet to a predetermined device or member. Then, the LED chips are transferred.

In the transfer of electronic components as described above, it is necessary to improve production costs (reduce required materials, shorten required time and man-hours, etc.), positional accuracy of electronic components, and achieve both fixability and releasability of electronic components from adhesive sheets. Prevention of contamination of electronic parts, prevention of damage to electronic parts, etc. are required.

Patent No. 5875850 Patent No. 6053756

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a pressure-sensitive adhesive sheet that can be used when transferring electronic components, which can contribute to the improvement of production costs, To provide a pressure-sensitive adhesive sheet which is excellent in the positional accuracy of components, the fixability of electronic components to the pressure-sensitive adhesive sheet and the releasability thereof, and which can prevent contamination of electronic components and damage to electronic components.

[1] The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer composed of an active energy ray-curable pressure-sensitive adhesive, wherein the active energy ray-curable pressure-sensitive adhesive is an ultraviolet absorber and/or a photopolymerizable The adhesive layer has an initial indentation modulus of 4 MPa or less at 23°C, and the indentation modulus of elasticity at 23°C of the adhesive layer is 150 MPa or more at 23°C after being irradiated with ultraviolet rays of 460 mJ/ ^cm2 . The adhesive sheet has a light transmittance of 50% or less at a wavelength of 355 nm.
[2] In one embodiment, the adhesive sheet does not contain a substrate.
[3] In the adhesive sheet of [1] or [2] above, the stress relaxation rate of the adhesive layer after 600 seconds may be 10% or more.
[4] In the pressure-sensitive adhesive sheets of [1] to [3], the pressure-sensitive adhesive layer may have a thickness of 20 μm or less.
[5] In the pressure-sensitive adhesive sheets of [1] to [4] above, the active energy ray-curable pressure-sensitive adhesive contains a photopolymerization initiator, and the photopolymerization initiator has two or more photodegradable groups. may
[6] In the adhesive sheet of [1] to [5] above, the active energy ray-curable adhesive contains a photopolymerization initiator, and the photopolymerization initiator is a compound containing a phosphorus atom and/or a nitrogen atom. There may be.
[7] In the pressure-sensitive adhesive sheets of [1] to [6] above, the active energy ray-curable pressure-sensitive adhesive contains an active energy ray-reactive compound, and the active energy ray-reactive compound has 5 or more functional groups. It may be a polyfunctional (meth)acrylate.
[8] The pressure-sensitive adhesive sheets of [1] to [7] above may be used for transferring electronic components.
[9] The pressure-sensitive adhesive sheets of [1] to [8] above may be used for transferring electronic components including catching electronic components by a laser lift-off process and then peeling off electronic components by laser light irradiation.
[10] In the adhesive sheets of [8] to [9] above, the electronic component may be a mini LED or a micro LED.
[11] According to another aspect of the present invention, a method for transferring electronic components is provided. This method of transferring electronic components is a method of transferring electronic components using the adhesive sheet.
[12] In one embodiment, the method for transferring electronic components includes a first step of transferring a plurality of electronic components arranged on a substrate onto the adhesive layer of the adhesive sheet; A second step of transferring the electronic component on the sheet to another member is included.
[13] In one embodiment, the same adhesive sheet is used in the first step and the second step.

According to the present invention, a pressure-sensitive adhesive sheet that can be used when transferring electronic components can contribute to an improvement in production costs, and is excellent in the positional accuracy of the electronic components and in the fixability and peelability of the electronic components from the pressure-sensitive adhesive sheet. , it is possible to provide a pressure-sensitive adhesive sheet that can prevent contamination of electronic parts and damage to electronic parts.

(a) is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention. (b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention;

A. Outline of Adhesive Sheet FIG. 1(a) is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention. The adhesive sheet 100 according to this embodiment comprises an adhesive layer 10 . The adhesive layer 10 is composed of an active energy ray-curable adhesive. The active energy ray-curable pressure-sensitive adhesive contains an ultraviolet absorber and/or a photopolymerization initiator. FIG. 1(b) is a schematic cross-sectional view of an adhesive sheet according to one embodiment of the present invention. The adhesive sheet 200 according to this embodiment further comprises a substrate 20 with an adhesive layer 10 disposed on at least one side of the substrate 20 . Although not shown, the pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the outside of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface until it is used. In addition, the pressure-sensitive adhesive sheet may further contain any appropriate other layer as long as the effects of the present invention can be obtained. In addition, in the present invention, as described later, the adherend can be peeled off satisfactorily due to the generation of strain due to the reduction in the adhesive strength of the adhesive layer and the increase in the elastic modulus. The pressure-sensitive adhesive sheet can be constructed without providing a layer (so-called separation layer) other than the pressure-sensitive adhesive layer for separating the body. In one embodiment, the pressure-sensitive adhesive sheet is used for transferring electronic components. More specifically, the pressure-sensitive adhesive sheet can be used for transferring electronic parts, including receiving electronic parts by a laser lift-off process and then peeling off the electronic parts by laser light irradiation. Examples of electronic components include mini-LEDs and micro-LEDs.

In one embodiment, the adhesive sheet does not contain a base material. In one embodiment, the pressure-sensitive adhesive sheet of the present invention is composed of only one pressure-sensitive adhesive layer, as shown in FIG. 1(a). A pressure-sensitive adhesive sheet that does not contain a substrate is preferable because it is excellent in energy utilization efficiency when an adherend is peeled off by irradiation with a laser beam. In another embodiment, the pressure-sensitive adhesive sheet of the present invention comprises a base material and a pressure-sensitive adhesive layer, as shown in FIG. without).

The pressure-sensitive adhesive layer has an initial indentation elastic modulus of 4 MPa or less at 23°C. In the present invention, since the pressure-sensitive adhesive layer has such an indentation elastic modulus, when the electronic component is attached, a part of the electronic component can preferably be embedded in the pressure-sensitive adhesive layer, The electronic component can be temporarily fixed with good fixability. For example, as will be described later, in the case of transferring an electronic component from a hard substrate to an adhesive sheet, displacement of the adherend, tilting of the adherend, and the like are prevented when the hard substrate is removed. The indentation modulus can be measured by the single indentation method at 23° C. with an indentation speed of 10 nm/s and an indentation depth of 100 nm.

In one embodiment, the adhesive sheet transfers a plurality of electronic components (e.g., LED chips) arranged on a substrate (e.g., a hard substrate such as a sapphire substrate) to the adhesive sheet; Transferring the electronic component on to another member; thus can be used. In one embodiment, the transfer of the electronic component from the substrate to the adhesive sheet can be performed by a process including irradiating the substrate/electronic component interface portion with laser light, that is, a laser lift-off process. According to the present invention, as described above, it is possible to arrange the electronic component on the adhesive sheet in a preferable state such as preventing the electronic component to be adhered from tilting. It is possible to receive it favorably. Moreover, when a laser lift-off process is employed, it is possible to prevent contaminants generated from the pressure-sensitive adhesive layer from adhering to the electronic component, which is the adherend, due to the influence of laser light irradiation.

Also, the transfer from the adhesive sheet to another member can be performed by laser light irradiation. In the present invention, since the pressure-sensitive adhesive layer contains an ultraviolet absorber or a photopolymerization initiator, the adherend (electronic component) can be peeled off by laser light irradiation. More specifically, by irradiating the adhesive layer with laser light, the ultraviolet absorber or photopolymerization initiator is heated and the adhesive layer is distorted. sexuality emerges. According to the present invention, as described above, the pressure-sensitive adhesive layer can be distorted in a minute range. It can be peeled off. By using such a pressure-sensitive adhesive sheet, it is possible to omit cleaning of the electronic parts after peeling. In addition, even when a small electronic component that requires peeling and a small electronic component that does not require peeling are temporarily fixed side by side, only the small electronic component that requires peeling can be peeled off. can also prevent unnecessary desorption of

As described above, the pressure-sensitive adhesive sheet of the present invention exhibits excellent properties in both receiving electronic parts by the laser lift-off process and peeling the electronic parts by laser light irradiation. Therefore, according to the present invention, when transferring an electronic component by a method including receiving the electronic component by a laser lift-off process and peeling off the electronic component by laser light irradiation, the transfer is completed using only the adhesive sheet. can be made Since a plurality of adhesive sheets are not required, the number of transfer processes can be reduced, and as a result, electronic components can be transferred with high positional accuracy. Also, production costs can be reduced.

The adhesive layer is composed of an active energy ray-curable adhesive. In a pressure-sensitive adhesive sheet containing an active energy ray-curable pressure-sensitive adhesive, the adhesive strength of the entire pressure-sensitive adhesive layer is reduced by irradiation with an active energy ray. The entire adhesive layer of the adhesive sheet to which the adherend (electronic component) is attached is irradiated with active energy rays to reduce the adhesive strength, and then the laser beam is irradiated as described above to remove the adhesive. It is possible to prevent adhesive residue later. By using such an adhesive sheet, it is possible to omit cleaning of the electronic parts after peeling. Moreover, by forming an adhesive layer containing an active energy ray-curable adhesive, the laser output at the time of peeling can be reduced. Since the pressure-sensitive adhesive sheet of the present invention exhibits releasability with a low-power laser beam, if the pressure-sensitive adhesive sheet is used, the damage to the electronic component that is the adherend during peeling is reduced, and the electronic component is damaged. can be prevented. In addition, since the peelability can be expressed by a laser beam with an output that does not cause decomposition (thermal decomposition) of the adhesive layer itself, contamination of the electronic component, which is the adherend, by the decomposition product of the adhesive layer is prevented. be able to. Examples of active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma currents, ionizing rays, and particle beams. Ultraviolet rays are preferred.

The pressure-sensitive adhesive layer is a layer having an indentation elastic modulus of 150 MPa or more at 23° C. after being irradiated with ultraviolet rays of 460 mJ/cm ² . If the adhesive layer is provided with such an indentation elastic modulus after ultraviolet irradiation, the adhesive layer is distorted by irradiation with a low-energy laser beam, and as a result, the adherend (electronic component) is improved. can be peeled off. Also, it is possible to prevent the contamination of the electronic component at the time of peeling.

The light transmittance of the adhesive sheet of the present invention at a wavelength of 355 nm is 50% or less. In the present invention, by lowering the light transmittance, the laser output at the time of peeling can be lowered. Since the pressure-sensitive adhesive sheet of the present invention exhibits releasability with a low-power laser beam, if the pressure-sensitive adhesive sheet is used, the damage to the electronic component that is the adherend during peeling is reduced, and the electronic component is damaged. can be prevented. The light transmittance of the adhesive sheet of the present invention at a wavelength of 355 nm is preferably 40% or less, more preferably 30% or less. Within such a range, the above effects are more pronounced. The light transmittance of the adhesive sheet is the light transmittance in the thickness direction of the adhesive sheet, and is the light transmittance measured for all the constituent layers of the adhesive sheet. In the present invention, the light transmittance of the pressure-sensitive adhesive sheet at a wavelength of 355 nm can be controlled by adjusting the content of the ultraviolet absorber contained in the pressure-sensitive adhesive layer. The light transmittance of the adhesive sheet at a wavelength of 355 nm can also be controlled by the composition of the base polymer and the photopolymerization initiator that constitute the adhesive layer. For example, the light transmittance of the adhesive sheet at a wavelength of 355 nm can be controlled by the type and amount of the photopolymerization initiator contained in the adhesive layer, particularly by the compatibility between the photopolymerization initiator and the base polymer.

The visible light transmittance of the adhesive sheet is preferably 50% or higher, more preferably 60% or higher, and even more preferably 70% or higher. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet from which the adherend to be peeled can be well visually recognized through the pressure-sensitive adhesive sheet when the adherend is peeled off by laser light irradiation. The higher the visible light transmittance of the adhesive sheet, the better, but the upper limit is, for example, 95% (preferably 100%).

The haze value of the adhesive sheet is preferably 70% or less, more preferably 65% or less. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet from which the adherend to be peeled can be well visually recognized through the pressure-sensitive adhesive sheet when the adherend is peeled off by laser light irradiation. The haze value of the adhesive sheet is preferably as low as possible, but its lower limit is, for example, 0.1%.

The initial adhesive force A at 23° C. immediately after the adhesive sheet is attached to a stainless steel plate is preferably 0.1 N/20 mm to 15 N/20 mm, more preferably 0.5 N/20 mm to 10 N/20 mm. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet that can hold an adherend well. Adhesion is measured according to JIS Z 0237:2000. Specifically, the pressure-sensitive adhesive sheet was attached to a stainless steel plate (arithmetic mean surface roughness Ra: 50 ± 25 nm) by reciprocating a 2 kg roller once, left at 23 ° C. for 30 minutes, and then peeled at a peel angle of 180 °. It is measured by peeling off the pressure-sensitive adhesive sheet at a speed (pulling speed) of 300 mm/min. The pressure-sensitive adhesive layer changes its adhesive strength due to irradiation with active energy rays and laser light. As used herein, the term "initial adhesive strength" means the adhesive strength before irradiation with active energy rays and laser light. .

In one embodiment, the adhesive force B at 23° C. after the adhesive sheet is attached to a stainless steel plate and irradiated with ultraviolet rays of 300 mJ/cm ² (also referred to as post-curing adhesive force B) is preferably 0.2 N. /20 mm or less, more preferably 0.01 N/20 mm to 0.2 N/20 mm, and more preferably 0.02 N/20 mm to 0.15 N/20 mm. Within such a range, a pressure-sensitive adhesive sheet with little adhesive residue can be obtained. The ultraviolet irradiation is performed by, for example, using an ultraviolet irradiation device (manufactured by Nitto Seiki Co., Ltd., trade name “UM-810”) and applying ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, integrated light amount: 300 mJ/cm ² ) to the adhesive layer. is performed by irradiating to

The reduction rate of the post-curing adhesive strength B with respect to the initial adhesive strength A is preferably 90% or more, more preferably 95% or more. Within such a range, a pressure-sensitive adhesive sheet with excellent peelability can be obtained. The rate of decrease (%) can be obtained from the formula (initial adhesive strength A−adhesive strength after curing B)/initial adhesive strength A×100.

The thickness of the adhesive sheet is preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm.

B. Adhesive Layer The thickness of the adhesive layer is preferably 20 μm or less. Within such a range, it is possible to lower the laser output at the time of peeling, and to obtain a pressure-sensitive adhesive sheet with excellent peelability. The thickness of the adhesive layer is more preferably 15 μm or less, still more preferably 10 μm or less, and more preferably 1 μm to 10 μm. With such a range, the above effect becomes remarkable.

As described above, the pressure-sensitive adhesive layer has an initial indentation elastic modulus of 4 MPa or less at 23°C. The initial indentation modulus of the pressure-sensitive adhesive layer at 23° C. is preferably 3 MPa or less, more preferably 2 MPa or less. Within such a range, the above effects of the present invention become remarkable. The initial indentation modulus of the pressure-sensitive adhesive layer at 23° C. is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, still more preferably 0.3 MPa or more, and particularly preferably 0.7 MPa. That's it. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet that is less likely to stain an adherend and has excellent releasability.

As described above, the pressure-sensitive adhesive layer is a layer having an indentation modulus of elasticity at 23° C. of 150 MPa or more after being irradiated with ultraviolet rays of 460 mJ/cm ² . The pressure-sensitive adhesive layer preferably has an indentation modulus of 200 MPa or more at 23° C., more preferably 300 MPa or more, more preferably 400 MPa or more, after irradiation with ultraviolet rays of 460 mJ/cm ² . It is more preferable to be a layer having a tensile strength of 500 MPa or higher, particularly preferably a layer having a tensile strength of 800 MPa or higher. With such a range, the above effect becomes remarkable. The upper limit of the indentation modulus of the pressure-sensitive adhesive layer after irradiation with ultraviolet rays of 460 mJ/cm ² is, for example, 8000 MPa (preferably 5000 MPa, more preferably 4000 MPa).

The stress relaxation rate of the pressure-sensitive adhesive layer after 600 seconds is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet with excellent chip retention. Specifically, it is possible to obtain a pressure-sensitive adhesive sheet in which the adherend (electronic component) is less likely to tilt on the pressure-sensitive adhesive layer even with the lapse of time after placement of the adherend (electronic component). By using such an adhesive sheet, electronic components can be transferred with good positional accuracy. The upper limit of the stress relaxation rate of the adhesive layer after 600 seconds is, for example, 100% (preferably 80%). The stress relaxation rate of the adhesive layer after 600 seconds is the stress value A (MPa) immediately after stretching the adhesive layer by 50% in the length direction at an environmental temperature of 23 ° C. for a cylindrical sample of the adhesive layer. and the stress value B (MPa) after 600 seconds in the 50% elongation state, it can be obtained by the formula (stress relaxation rate (%) = (AB) / A × 100).

As described above, the adhesive layer is composed of an active energy ray-curable adhesive. The active energy ray-curable pressure-sensitive adhesive may contain the ultraviolet absorber and/or the photopolymerization initiator.

(Active energy ray-curable adhesive)
In one embodiment, the active energy ray-curable pressure-sensitive adhesive is an active energy ray-curable adhesive containing a base polymer as a base material and an active energy ray-reactive compound (monomer or oligomer) capable of bonding with the base polymer. An adhesive (A1) is used. In another embodiment, an active energy ray-curable pressure-sensitive adhesive (A2) containing an active energy ray-reactive polymer as a base polymer is used. Preferably, the base polymer has functional groups capable of reacting with the photoinitiator. Examples of the functional group include hydroxyl group and carboxyl group.

Examples of the base polymer used in the adhesive (A1) include natural rubber, polyisobutylene rubber, styrene/butadiene rubber, styrene/isoprene/styrene block copolymer rubber, recycled rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber. rubber-based polymers such as (NBR); silicone-based polymers; and acrylic polymers. These polymers may be used alone or in combination of two or more. Among them, acrylic polymers are preferred.

Examples of acrylic polymers include homopolymers and copolymers of hydrocarbon group-containing (meth)acrylic esters such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters. a copolymer of the hydrocarbon group-containing (meth)acrylic acid ester and another copolymerizable monomer; (Meth)acrylic acid alkyl esters include, for example, (meth)acrylic acid methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, iso Pentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester or lauryl ester, tridecyl ester, tetradecyl ester, hexa Decyl esters, octadecyl esters, and eicosyl esters are included. (Meth)acrylic acid cycloalkyl esters include, for example, cyclopentyl and cyclohexyl esters of (meth)acrylic acid. (Meth)acrylic acid aryl esters include, for example, phenyl (meth)acrylate and benzyl (meth)acrylate. The content of structural units 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, relative to 100 parts by weight of the base polymer.

Examples of other copolymerizable monomers include carboxy group-containing monomers, acid anhydride monomers, hydroxy group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, acrylamide, and acrylonitrile. Examples include functional group-containing monomers. Carboxy group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Anhydride monomers include, for example, maleic anhydride and itaconic anhydride. Examples of hydroxy 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. Glycidyl group-containing monomers include, for example, glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Sulfonic acid group-containing monomers include, for example, styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth) ) acryloyloxynaphthalene sulfonic acid. Phosphate group-containing monomers include, for example, 2-hydroxyethyl acryloyl phosphate. Acrylamides include, for example, N-acryloylmorpholine. These may be used individually by 1 type, and may be used in combination of 2 or more type. The content of structural units derived from the copolymerizable monomer is preferably 60 parts by weight or less, more preferably 40 parts by weight or less, relative to 100 parts by weight of the base polymer.

The acrylic polymer may contain structural units derived from polyfunctional monomers in order to form a crosslinked structure 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, (meth)acrylates, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate (i.e. polyglycidyl (meth)acrylate), polyester (meth)acrylate ) acrylates, and urethane (meth)acrylates. These may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the structural unit derived from the polyfunctional monomer is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, relative to 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, more preferably 200,000 to 2,000,000. A 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 adhesive (A1) include a functional group having a polymerizable carbon-carbon multiple bond such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, and an acetylene group. photoreactive monomers or oligomers having Specific examples of the photoreactive monomer include trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol mono Hydroxy penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate ( Esterified product of meth)acrylic acid and polyhydric alcohol; polyfunctional urethane (meth)acrylate; epoxy (meth)acrylate; oligoester (meth)acrylate and the like. Monomers such as methacryloylisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), 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 100-3000.

In one embodiment, a polyfunctional (meth)acrylate having 5 or more functional groups or a polyfunctional (meth)acrylate oligomer having 5 or more functional groups is used as the active energy ray-reactive compound. By using such an active energy ray-reactive compound, it is possible to form a pressure-sensitive adhesive layer that can become highly elastic when irradiated with an active energy ray (for example, ultraviolet rays). If the elastic modulus of the pressure-sensitive adhesive layer can be increased, the peeling operation can be performed with a low-power laser beam.

Further, as the active energy ray-reactive compound, monomers such as epoxidized butadiene, glycidyl methacrylate, acrylamide, and vinylsiloxane; or oligomers composed of such monomers may be used.

Furthermore, as the active energy ray-reactive compound, a mixture of an organic salt such as an onium salt and a compound having a plurality of heterocycles in the molecule may be used. When the mixture is irradiated with an active energy ray (e.g., ultraviolet rays, electron beams), the organic salt is cleaved to generate ions, which act as starting species to cause a heterocyclic ring-opening reaction to form a three-dimensional network structure. can. Examples of the organic salts include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, borate salts and the like. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, thiirane, aziridine and the like.

In the adhesive (A1), the content of the active energy ray-reactive compound is preferably 0.1 parts by weight to 500 parts by weight, more preferably 5 parts by weight to 300 parts by weight, with respect to 100 parts by weight of the base polymer. parts by weight, more preferably 40 to 150 parts by weight.

Examples of the active energy ray-reactive polymer (base polymer) contained in the adhesive (A2) include functional groups having carbon-carbon multiple bonds such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, and acetylene groups. polymer having Specific examples of active energy ray-reactive polymers include polymers composed of polyfunctional (meth)acrylates; photo-cationically polymerizable polymers; cinnamoyl group-containing polymers such as polyvinyl cinnamate; diazotized amino novolak resins; ; and the like.

In one embodiment, the active energy configured by introducing an active energy ray-polymerizable carbon-carbon multiple bond into the side chain, main chain and/or main chain end of the acrylic polymer (precursor resin) A linear reactive polymer is used. As a technique for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer (precursor resin), for example, a raw material monomer containing a monomer having a predetermined functional group (first functional group) is copolymerized. After obtaining an acrylic polymer (precursor resin), a predetermined functional group (second functional group) and a radiation-polymerizable carbon-carbon double a compound having a bond (hereinafter also simply referred to as a compound having a carbon double bond) with an acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond. , are mentioned.

The amount of the compound having a carbon double bond introduced is preferably 10 parts by weight or more, more preferably 12 parts by weight or more, relative to 100 parts by weight of the solid content of the acrylic polymer (precursor resin). It is preferably 15 parts by weight or more. Within such a range, it is possible to obtain a low-polarity active energy ray-reactive polymer (base polymer). Also, it is possible to detach the adherend preferably by irradiating laser light with low energy. The upper limit of the introduction amount of the compound having a carbon double bond is, for example, 80 parts by weight (preferably 60 parts by weight, more preferably 50 parts by weight) with respect to 100 parts by weight of the solid content of the acrylic polymer (precursor resin). is.

Combinations of the first functional group and the second functional group include, for example, 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 hydroxy groups. Among these combinations, a combination of a hydroxy group and an isocyanate group and a combination of an isocyanate group and a hydroxy group are preferable from the viewpoint of ease of reaction tracking. In addition, it is technically difficult to produce a polymer having a highly reactive isocyanate group. More preferred is when the group is a hydroxy group and said second functional group is 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, m-isopropenyl-α, and α-dimethylbenzyl isocyanate. Further, the acrylic polymer having the first functional group preferably contains a structural unit derived from the hydroxy group-containing monomer, such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. It is also preferable to contain a constitutional unit derived from an ether-based compound.

The glass transition temperature Tg of the active energy ray-reactive polymer (base polymer) is preferably −60° C. or higher, more preferably −50° C. or higher, and still more preferably −40° C. or higher. Within such a range, it is possible to obtain a low-polarity active energy ray-reactive polymer (base polymer). Also, it is possible to detach the adherend preferably by irradiating laser light with low energy. The upper limit of the glass transition temperature Tg of the active energy ray-reactive polymer (base polymer) is preferably 0°C, more preferably -20°C. The Tg of the base polymer is based on the Tg of the homopolymer (homopolymer) of each monomer constituting the base polymer and the weight fraction (copolymerization ratio based on weight) of the monomer, from the Fox formula It means the desired value. The Fox equation is a relational expression between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1/Tg=Σ(Wi/Tgi)
In the above Fox formula, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of the monomer i in the copolymer (weight-based copolymerization ratio), and Tgi is the homopolymer of the monomer i. represents the glass transition temperature (unit: K). As the Tg of the homopolymer, the values described in known documents shall be adopted.

The 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 are as described above.

In one embodiment, the active energy ray-curable pressure-sensitive adhesive may contain a photosensitizer.

In one embodiment, the photosensitizer can be used in combination with the photopolymerization initiator. The photosensitizer can generate radicals from the photopolymerization initiator by passing the energy obtained by itself absorbing light to the photopolymerization initiator, so the absorption peak of the photopolymerization initiator itself is Polymerization can proceed with light on the long wavelength side. Therefore, by including a photosensitizer, it is possible to increase the difference between the absorption wavelength of the ultraviolet absorber and the wavelength at which radicals can be generated from the photopolymerization initiator. As a result, the photopolymerization of the pressure-sensitive adhesive layer and the peeling by the ultraviolet absorber can be performed without affecting each other. In one embodiment, 2,2-dimethoxy-1,2-diphenylethan-1-one (for example, manufactured by BASF, trade name “Irgacure 651”) as a photopolymerization initiator, and a photosensitizer are used together. Such photosensitizers include trade name "UVS-581" manufactured by Kawasaki Kasei Co., Ltd., 9,10-diethoxyanthracene (for example, trade name "UVS1101" manufactured by Kawasaki Kasei Co., Ltd.), and the like. be done.

Other examples of the photosensitizer include 9,10-dibutoxyanthracene (eg, trade name “UVS-1331” manufactured by Kawasaki Chemical Industries, Ltd.), 2-isopropylthioxanthone, benzophenone, thioxanthone derivatives, 4,4 '-bis(dimethylamino)benzophenone and the like. Thioxanthone derivatives include, for example, ethoxycarbonylthioxanthone and isopropylthioxanthone.

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

Preferably, the active energy ray-curable pressure-sensitive adhesive contains a cross-linking agent. Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, Examples include metal chelate cross-linking agents, metal salt cross-linking agents, carbodiimide cross-linking agents, amine cross-linking agents and the like.

The content of the cross-linking agent is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, with respect to 100 parts by weight of the base polymer of the adhesive.

In one embodiment, an isocyanate-based cross-linking agent is preferably used. An isocyanate-based cross-linking agent is preferable because it can react with various functional groups. Specific examples of the isocyanate-based cross-linking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; aromatic isocyanates such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate L”), tri Methylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"), etc. isocyanate adduct; and the like. Preferably, a cross-linking agent having 3 or more isocyanate groups is used.

The active energy ray-curable adhesive may further contain any suitable additive as necessary. Additives include, for example, active energy ray polymerization accelerators, radical scavengers, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, and fillers. agents, anti-aging agents, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

(Ultraviolet absorber)
As the UV absorber, any suitable UV absorber can be used as long as it is a compound that absorbs UV light (for example, wavelength of 355 nm). Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Among them, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferred, and triazine-based UV absorbers are particularly preferred. In particular, when an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive, triazine-based ultraviolet absorbers are preferably used because of their high compatibility with the base polymer of the acrylic pressure-sensitive adhesive. The triazine-based ultraviolet absorber is more preferably composed of a compound having a hydroxyl group, and particularly preferably an ultraviolet absorber composed of a hydroxyphenyltriazine-based compound (hydroxyphenyltriazine-based ultraviolet absorber).

Examples of hydroxyphenyltriazine-based UV absorbers include 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C10 -Reaction product with C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4,6-bis-(2, 4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidate reaction product (trade name "TINUVIN 405", manufactured by BASF), 2,4-bis(2-hydroxy- 4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3 ,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine- 2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name “ADEKA STAB LA-46”, manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1 -octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479", manufactured by BASF), trade name "TINUVIN 477" manufactured by BASF and so on.

Benzotriazole-based UV absorbers (benzotriazole-based compounds) include, for example, 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), benzene Ester compound of propanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (trade name "TINUVIN 384 -2", manufactured by BASF), octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[ A mixture of 3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2yl)phenyl]propionate (trade name "TINUVIN 109", manufactured by BASF), 2-(2H-benzotriazole -2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6- (1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), methyl 3-(3-(2H-benzotriazole) -2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 reaction product (trade name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl )-p-cresol (trade name “TINUVIN P”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF) ), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name “TINUVIN 328”, manufactured by BASF), 2-(2H-benzotriazol-2-yl) -4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)- 4-(1,1,3,3-tetramethylbutyl)phenol] (trade name “TINUVIN 360”, manufactured by BASF), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert -Butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 reaction product (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4- Methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name " Sumisorb 250", manufactured by Sumitomo Chemical Co., Ltd.), 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB 703", Sipro Kasei Co., Ltd.) ), 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol (trade name “SEESORB 706”, manufactured by Sipro Kasei Co., Ltd. ), 2-(4-benzoyloxy-2-hydroxyphenyl)-5-chloro-2H-benzotriazole (trade name “SEESORB 7012BA” manufactured by Shipro Kasei Co., Ltd.), 2-tert-butyl-6-(5-chloro -2H-benzotriazol-2-yl)-4-methylphenol (trade name "KEMISORB 73", manufactured by Chemipro Kasei Co., Ltd.), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4 -tert-octylphenol] (trade name "ADEKA STAB LA-31", manufactured by ADEKA Corporation), 2-(2H-benzotriazol-2-yl)-p-cellulose (trade name "ADEKA STAB LA-32", ) manufactured by ADEKA), 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol (trade name “ADEKA STAB LA-36” manufactured by ADEKA Co., Ltd.), etc. mentioned.

The ultraviolet absorber may be a dye or pigment. Examples of pigments include azo-based, phthalocyanine-based, anthraquinone-based, lake-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxandine-based, isoindolinone-based, and quinophthalone-based pigments. Dyes include azo, phthalocyanine, anthraquinone, carbonyl, indigo, quinoneimine, methine, quinoline, and nitro dyes.

The molecular weight of the compound constituting the ultraviolet absorber is preferably 1000 or less, more preferably 800 or less, and even more preferably 600 or less. The UV absorber having a molecular weight within the above range has excellent compatibility with the base polymer. It becomes possible to peel with low laser energy. As a result, thermal decomposition of the adhesive layer can be prevented. By forming such a pressure-sensitive adhesive layer, it is possible to obtain a pressure-sensitive adhesive sheet that does not easily stain an adherend. The lower limit of the molecular weight of the compound constituting the ultraviolet absorber is 100, for example.

The maximum absorption wavelength of the ultraviolet absorber is preferably 300 nm to 450 nm, more preferably 320 nm to 400 nm, still more preferably 330 nm to 380 nm. The difference between the maximum absorption wavelength of the ultraviolet absorber and the maximum absorption wavelength of the photopolymerization initiator is preferably 10 nm or more, more preferably 25 nm or more.

The content of the ultraviolet absorber is preferably 1 part by weight to 50 parts by weight, more preferably 2 parts by weight to 30 parts by weight, and still more preferably 100 parts by weight of the base polymer in the pressure-sensitive adhesive layer. is 3 to 25 parts by weight. Within such a range, when the adhesive strength of the entire adhesive layer is satisfactorily lowered by irradiation with active energy rays, the curing of the adhesive layer proceeds well, and good peelability is achieved by laser light irradiation. can be obtained.

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

In one embodiment, a photopolymerization initiator having two or more (preferably two to five) photodegradable groups is used as the photopolymerization initiator. By using such a photopolymerization initiator, it is possible to form a pressure-sensitive adhesive layer that can become highly elastic when irradiated with active energy rays (eg, ultraviolet rays). If the elastic modulus of the pressure-sensitive adhesive layer can be increased, the peeling operation can be performed with a low-power laser beam. A photodegradable group means a functional group that absorbs irradiated active energy rays and generates radicals. mentioned.

Photopolymerization initiators having two or more photodegradable groups include, for example, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl -Propan-1-one (trade name Omnirad 127, manufactured by BASF Japan), 1-[4-(4-benzoxylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propane-1 -one (trade name ESURE 1001M), methylbenzoylformate (trade name SPEEDCURE MBF manufactured by LAMBSON), O-ethoxyimino-1-phenylpropan-1-one (trade name SPEEDCURE PDO manufactured by LAMBSON), oligo [2-hydroxy-2 -methyl-4-(1-methylvinyl)phenyl]propanone (trade name ESCURE KIPI50 manufactured by Lamberti) and the like.

In one embodiment, a compound containing a phosphorus atom and/or a nitrogen atom is used as the photopolymerization initiator. Such photopolymerization initiators include, for example, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name Omnirad 907, manufactured by BASF Japan), 2-benzyl- 2-(dimethylamino)-4'-morpholinobtyrophenone (trade name Omnirad 369, manufactured by BASF Japan), 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl) Butan-1-one (trade name Omnirad 379, manufactured by BASF Japan), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name Omnirad 819, manufactured by BASF Japan), 2,4,6-trimethylbenzoyl-diphenyl Phosphine oxide (trade name: OmniradTPO, manufactured by BASF Japan), 1,2-octanedione-1-[4-(phenylthio)phenyl-2-(O-benzoyloxime)] (trade name: OmniradOXE01, manufactured by BASF Japan), ethanone -1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) (trade name OmniradOXE02, manufactured by BASF Japan) and the like. By using such a photopolymerization initiator, it is possible to form a pressure-sensitive adhesive layer that can become highly elastic when irradiated with active energy rays (eg, ultraviolet rays). If the elastic modulus of the pressure-sensitive adhesive layer can be increased, the peeling operation can be performed with a low-power laser beam.

The content of the photopolymerization initiator is preferably 1 part by weight to 30 parts by weight, more preferably 2 parts by weight to 20 parts by weight, with respect to 100 parts by weight of the base polymer in the adhesive layer. It is preferably 3 to 15 parts by weight. Within such a range, when the adhesive strength of the entire adhesive layer is favorably reduced by irradiation with an active energy ray, the curing of the adhesive layer proceeds favorably, and distortion of the adhesive layer due to laser light irradiation is achieved. It is possible to obtain a pressure-sensitive adhesive sheet with a large amount and good releasability.

C. Substrate The substrate may be composed of any suitable resin. Examples of the resin include polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, polybutene-based resins, and polymethylpentene-based resins, polyurethane-based resins, polyester-based resins, polyimide-based resins, polyetherketone-based resins, and polystyrene-based resins. Resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicon resins, cellulose resins, ionomer resins, and the like can be mentioned. Among them, polyolefin resins are preferred.

The thickness of the base material is preferably 2 μm to 300 μm, more preferably 2 μm to 100 μm, still more preferably 2 μm to 50 μm.

The light transmittance of the substrate at a wavelength of 355 nm is preferably 70% or higher, more preferably 80% or higher, even more preferably 90% or higher, and particularly preferably 95% or higher. The upper limit of the total light transmittance of the substrate is, for example, 98% (preferably 99%).

D. Production method of pressure-sensitive adhesive sheet The above-mentioned pressure-sensitive adhesive sheet can be produced by any appropriate method. A pressure-sensitive adhesive sheet can be obtained, for example, by applying the above pressure-sensitive adhesive onto a substrate or a release liner. Coating methods include bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. Various methods can be employed. Alternatively, a method of forming a pressure-sensitive adhesive layer on a release liner and then attaching it to a base material may be adopted.

E. Method for Transferring Electronic Components In one embodiment, there is provided a method for transferring electronic components using the adhesive sheet. The transfer method includes, for example, a first step of transferring a plurality of electronic components arranged on a substrate onto an adhesive layer of the adhesive sheet; and transferring the electronic components on the adhesive sheet to another member. A second step is included. Preferably, the same adhesive sheet is used in the first step and the second step. That is, in the transfer method, the electronic component can be transferred without including an additional transfer step.

In the first step, the transfer of the electronic component from the substrate to the adhesive sheet can be performed by a process including irradiating the substrate/electronic component interface portion with laser light, that is, a laser lift-off process. The conditions for the laser lift-off process can be any suitable conditions.

For example, a hard substrate such as a sapphire substrate may be used as the substrate.

In one embodiment, the second step includes the following operations: (i) irradiating the adhesive sheet with active energy rays (e.g., ultraviolet rays) to form the adhesive layer of the adhesive sheet; (ii) irradiating a laser beam to a portion where peelability is desired to cause strain in the adhesive layer to further reduce the adhesive force. According to this method, the electronic component can be detached only at the location irradiated with the laser beam. By using the pressure-sensitive adhesive sheet of the present invention, the adhesive force can be reduced to the extent that it naturally falls, so even very small (for example, 50 μm square) electronic components can be individually peeled off. be.

The active energy ray in (i) above may be irradiated to the entire surface of the pressure-sensitive adhesive layer. In one embodiment, ultraviolet rays are irradiated with an integrated light amount of 200 mJ/cm ² to 600 mJ/cm ² .

As the laser light in (ii) above, for example, a laser light with a wavelength of 200 nm to 360 nm (preferably 355 nm) is used. Laser light output is, for example, 100 mJ/cm ² to 1200 mJ/cm ² .

In one embodiment, the electronic components are mini-LEDs or micro-LEDs.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Tests and evaluation methods in Examples are as follows. Also, "parts" and "%" are by weight unless otherwise specified.

(1) Adhesion The PET release liner of the adhesive sheet was peeled off, and PET (Lumirror S10 manufactured by Toray) having a thickness of 25 μm was attached. After that, the PET release liner on the other side was peeled off, and a 2-kg roller was reciprocated once to bond it to SUS304. Measurement temperature: 23°C), and the adhesive force was measured as the initial adhesive force.
In the same way, after bonding the adhesive sheet to SUS304, from the adhesive sheet side, using an ultraviolet irradiation device (manufactured by Nitto Seiki, trade name "UM-810"), ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, integrated light amount : 300 mJ/cm ² ), and the adhesive strength was measured in the same manner as the cured adhesive strength.

(2) Wavelength 355 nm light transmittance Peel off the PET release liner of the adhesive sheet, attach it to a large slide glass (manufactured by Matsunami Glass, trade name "S9111") using a hand roller, and peel off the PET release liner on the other side. Measurements were taken in this state. Specifically, a spectrophotometer (trade name “Spectrophotometer U-4100”, manufactured by Hitachi High-Tech Science) was used to measure the transmittance of the adhesive sheet itself at a wavelength of 355 nm for the adhesive sheet on the large slide glass. bottom.

(3) Indentation Modulus The PET release liner of the adhesive sheet was peeled off, and the adhesive sheet was attached to a large slide glass (manufactured by Matsunami Glass, trade name "S9111") using a hand roller. Using an ultraviolet irradiator (manufactured by Nitto Seiki, trade name "UM-810") from the side of the slide glass of the obtained sample, the entire surface was irradiated with ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, integrated light amount: 460 mJ/cm ² ). irradiated. After that, the other PET release liner was peeled off to expose the pressure-sensitive adhesive layer, and the indentation modulus was measured using a tripoindenter TI-950 manufactured by Hysitron. The measurements were made by the single indentation method at 23° C. with an indentation speed of 10 nm/s and an indentation depth of 100 nm.

(4) Stress Relaxation Rate After 600 Seconds The pressure-sensitive adhesive layer was cut into a size of 50 mm long×40 mm wide and rounded to obtain a cylindrical test piece (diameter: 0.5643 mm, length: 40 mm). This test piece was placed in an atmosphere of 23° C. and 50% RH with an initial chuck distance of 20 mm and a tensile speed of 50 mm/min using a tensile tester (trade name “AFX-50NX” manufactured by Shimadzu Corporation). It was stretched (elongated) to an elongation rate of 50% and then stopped, and the stress value A (MPa) was measured. After that, the stress value B (MPa) was measured 600 seconds after stopping. The stress relaxation rate was determined from the stress values A and B by the following formula.
Stress relaxation rate (%) = (AB) / A × 100

(5) Laser lift-off (LLO) evaluation After bonding an adhesive onto a 4-inch square quartz glass, a sapphire substrate was bonded so that the LED chip was on the adhesive surface. Bonding was performed using a protective tape applying device with a vacuum + press mechanism (trade name “DV 3000”, manufactured by Nitto Seiki Co., Ltd.), vacuum time: 90 seconds, crimping conditions: 0.25 MPa, crimping time: 0 seconds. .
After the pressure bonding was completed, the sapphire surface was irradiated with a laser (excimer laser manufactured by MRAYS) to carry out LLO. The LLO conditions were wavelength: 248 nm and energy density: 900 mJ/cm ³ . After LLO, the sapphire glass was removed and the yield was checked. Yield: 90% or more was rated good (◯), 80% or more and less than 90% was rated acceptable (Δ), and less than 80% was rated unsatisfactory (x).
The LED chips on the adhesive tape were observed using a confocal microscope (product name "OLS 5100", manufactured by Shimadzu Corporation), the tilt angles of 100 chips were measured, and the average value was calculated. If the average tilt value is 0.15° or less, it is excellent (◎); ).

(6) Laser Transfer Evaluation After LLO, the adhesive was photo-cured from the quartz glass side of the obtained sample in a nitrogen atmosphere using an ultraviolet irradiation device (trade name “UM 810”, manufactured by Nitto Seiki Co., Ltd.). . The curing conditions were set to 460 mJ/cm ² in terms of wavelength of 365 nm using ultraviolet light from a high-pressure mercury lamp.
After that, a laser (wavelength: 355 nm, pulse width: 5 ns) was irradiated only to the target chip position from the quartz glass side to perform Laser Transfer. A laser beam was irradiated from 100 mJ/cm ² to 1200 mJ/cm ² in steps of 100 mJ/cm ² , and the energy with the best positional accuracy was defined as the Energy value ^. A value of more than /cm ² and 1000 mJ/cm ² or less was rated as good (∘), and a value of greater than 1000 mJ/cm ² and transfer failure at 1200 mJ/cm ² was rated as fail (x).
The chip after transfer was observed using a digital microscope (trade name “VHX2000”, manufactured by Keyence Corporation) to evaluate the positional accuracy. A case where the deviation distance in the long side direction of the chip was 2 μm or less was evaluated as excellent (⊚), a case where the displacement was greater than 2 μm and 5 μm or less was evaluated as good (◯), and a deviation greater than 5 μm was evaluated as unsatisfactory (x).

[Production Example 1] Preparation of Acrylic Polymer A 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 above monomer composition, and 0.3 parts of benzoyl peroxide (BPO) were added. Parts by weight were charged and stirred at 60° C. for 5 hours. Then, it is cooled to room temperature, and 24 parts by weight of 2-methacryloyloxyethyl isocyanate is added and reacted to add an NCO group to the side chain terminal OH group of 2-hydroxyethyl acrylate in the copolymer, and carbon at the end. - An acrylic polymer solution A containing an acrylic polymer A having a carbon double bond was obtained.

[Production Example 2] Preparation of Acrylic Polymer B 100 parts by weight of 2-ethylhexyl acrylate, 25.5 parts by weight of acryloylmorpholine and 18.5 parts by weight of hydroxyethyl acrylate were mixed to prepare a monomer composition.
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 above monomer composition, and 0.3 parts of benzoyl peroxide (BPO) were added. Parts by weight were charged and stirred at 60° C. for 4 hours. Then, it is cooled to room temperature, and 12 parts by weight of 2-methacryloyloxyethyl isocyanate is added and reacted to add an NCO group to the side chain terminal OH group of 2-hydroxyethyl acrylate in the copolymer, and carbon at the end. - An acrylic polymer solution B containing an acrylic polymer B having a carbon double bond was obtained.

[Production Example 3] Preparation of Acrylic Polymer C 100 parts by weight of isononyl acrylate and 32 parts by weight of hydroxyethyl acrylate were mixed to prepare a monomer composition.
Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and 280 parts by weight of ethyl acetate, 132 parts by weight of the above monomer composition, and 0.2 parts by weight of benzoyl peroxide (BPO) were added under a nitrogen atmosphere. 3 parts by weight were charged and stirred at 60° C. for 4 hours. Then, it is cooled to room temperature, and 56 parts by weight of 2-methacryloyloxyethyl isocyanate is added and reacted to add an NCO group to the side chain terminal OH group of 2-hydroxyethyl acrylate in the copolymer, and carbon at the end. - An acrylic polymer solution C containing an acrylic polymer C having a carbon double bond was obtained.

[Production Example 4] Preparation of Acrylic Polymer D 88.8 parts by weight of 2-ethylhexyl acrylate and 11.2 parts by weight of hydroxyethyl acrylate were mixed to prepare a monomer composition.
Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 150 parts by weight of toluene, 100 parts by weight of the above monomer composition, and 0.3 parts of benzoyl peroxide (BPO) were added. Parts by weight were charged and stirred at 60° C. for 4 hours. Then, it is cooled to room temperature, and 12 parts by weight of 2-methacryloyloxyethyl isocyanate is added and reacted to add an NCO group to the side chain terminal OH group of 2-hydroxyethyl acrylate in the copolymer, and carbon at the end. - An acrylic polymer solution D containing an acrylic polymer D having a carbon double bond was obtained.

[Example 1]
(Preparation of adhesive)
Acrylic polymer solution A containing 100 parts by weight of acrylic polymer A, 3 parts by weight of a cross-linking agent (manufactured by Mitsui Chemicals, trade name "Takenate D-101A"), and an ultraviolet absorber (manufactured by BASF, trade name "Tinuvin PS". ) and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name “Omnirad TPO”) were added to obtain an adhesive (1).
(adhesive sheet)
The pressure-sensitive adhesive (1) was applied to the silicone-treated surface of a PET release liner (thickness: 38 μm) and then heated at 130° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 5 μm.
Using a hand roller, a PET release liner was laminated onto the adhesive layer to obtain a release liner-attached pressure-sensitive adhesive sheet.
The obtained pressure-sensitive adhesive sheet with a release liner was subjected to the above evaluation. Table 1 shows the results.

[Examples 2 to 14, Comparative Examples 1 to 5]
Same as Example 1 except that the acrylic polymer solution, cross-linking agent, ultraviolet absorber, active energy ray-reactive compound (oligomer), and photopolymerization initiator shown in Table 1 were used in the amounts shown in Table 1. to obtain an adhesive sheet. The obtained pressure-sensitive adhesive sheet was subjected to the above evaluation. Table 1 shows the results.
In the experimental examples using active energy ray-reactive compounds (oligomers), the oligomers were added during preparation of the adhesives to obtain the adhesives.
Compounds and the like used in Examples and Comparative Examples are as follows.
(crosslinking agent)
・ D-101A: isocyanate-based cross-linking agent, manufactured by Mitsui Chemicals, trade name “Takenate D-101A”
・Coronate HX: isocyanate-based cross-linking agent ・Manufactured by Tosoh Corporation, trade name “Coronate/HX”
(Ultraviolet absorber)
- Tinuvin PS: manufactured by BASF, trade name "Tinuvin PS", 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole Tinuvin 405: manufactured by BASF, trade name "Tinuvin 405", 2 Reaction product of -(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidate Tinuvin 460: BASF Corporation, trade name "Tinuvin 460", 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine Tinuvin 477: BASF Corporation, trade name “Tinuvin 460”, hydroxyphenyl triazine compound KEMISORB111: Chemipro Kasei Co., trade name “KEMISORB111”
・KEMIISORB71: manufactured by Chemipro Kasei, trade name “KEMIISORB71”,
(Active energy ray-reactive compound (oligomer))
・UV-1700TL: Urethane acrylate-based polyfunctional oligomer, manufactured by Nippon Synthetic Chemical Co., Ltd., trade name “UV-1700TL”
・DPHA: dipentaerythritol hexaacrylate (photoinitiator)
· Omni127D: manufactured by BASF, trade name "Omnirad127D", compound name: 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one
· OmniTPO: BASF Corporation, trade name "OmniradTPO", compound name: 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide
· Omni379: manufactured by BASF, trade name "Omnirad379", compound name: 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one
· Omni369: manufactured by BASF, trade name "Omnirad369", compound name: 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophone

REFERENCE SIGNS LIST 10 adhesive layer 20

base material

100, 200 adhesive sheet

Claims

A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer composed of an active energy ray-curable pressure-sensitive adhesive,
The active energy ray-curable adhesive contains an ultraviolet absorber and/or a photopolymerization initiator,
The pressure-sensitive adhesive layer has an initial indentation modulus at 23°C of 4 MPa or less,
The pressure-sensitive adhesive layer is a layer having an indentation elastic modulus of 150 MPa or more at 23° C. after being irradiated with ultraviolet rays of 460 mJ/cm 2 ,
The light transmittance of the pressure-sensitive adhesive sheet at a wavelength of 355 nm is 50% or less.
adhesive sheet.
The adhesive sheet according to claim 1, which does not contain a base material.
The pressure-sensitive adhesive sheet according to claim 1, wherein the stress relaxation rate of the pressure-sensitive adhesive layer after 600 seconds is 10% or more.
The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 20 µm or less.
The active energy ray-curable pressure-sensitive adhesive contains a photopolymerization initiator,
The photopolymerization initiator has two or more photodegradable groups,
The pressure-sensitive adhesive sheet according to claim 1.
The active energy ray-curable pressure-sensitive adhesive contains a photopolymerization initiator,
The photoinitiator is a compound containing a phosphorus atom and/or a nitrogen atom,
The pressure-sensitive adhesive sheet according to claim 1.
The active energy ray-curable pressure-sensitive adhesive contains an active energy ray-reactive compound,
The active energy ray-reactive compound is a polyfunctional (meth)acrylate having 5 or more functional groups,
The pressure-sensitive adhesive sheet according to claim 1.
The adhesive sheet according to claim 1, which is used for transferring electronic parts.
The pressure-sensitive adhesive sheet according to claim 1, which is used for transferring electronic components, including catching electronic components by a laser lift-off process and then peeling electronic components by laser light irradiation.
The adhesive sheet according to claim 8 or 9, wherein the electronic component is a mini LED or micro LED.
A method of transferring electronic components using the adhesive sheet according to any one of claims 1 to 7.
a first step of transferring a plurality of electronic components arranged on a substrate onto the adhesive layer of the adhesive sheet; and
Including a second step of transferring the electronic component on the adhesive sheet to another member,
The method for transferring electronic components according to claim 11 .
The method of transferring electronic components according to claim 12, wherein the same adhesive sheet is used in the first step and the second step.