Peeling method

Abstract

The present invention pertains to a separation method for separating an adherend from an adhesive layer by irradiating with light a laminate having laminated therein the adherend and the adhesive layer, the method including a step for irradiating the adhesive layer with light having a pulse width of one second or less, and a light irradiation amount of 1000 mJ / cm2 or more. The adhesive layer satisfies predetermined conditions on the minimum transmittance in a near-infrared ray range of wavelength of 800-2500 nm and the maximum transmittance in a visible light range of wavelength of 380-780 nm.

Description

[Technical Field]

[0001] The present invention relates to a method for peeling an adherend from a pressure-sensitive adhesive layer by irradiating a laminate in which a pressure-sensitive adhesive layer and an adherend are laminated with high-energy light. [Background technology]

[0002] As is well known, laminates formed by bonding adherends with a pressure-sensitive adhesive layer are widely used in various fields. Meanwhile, in recent years, due to increasing environmental awareness and cost reduction, resource conservation and recycling have become increasingly required. For example, in the fields of automobiles, machinery, electrical appliances, building materials, etc., improvements in yield, reworkability in processes, recyclability, workability, etc. are required.

[0003] Among these, when the adherend in the laminate is a very brittle or hard material, there is a problem that the reworkability is significantly poor. For example, from the viewpoint of product design, it is required that the adhesive layer has sufficient adhesive strength, but when at least one of the adherends is a hard material such as glass, the adherend cannot be bent in the peeling direction, and peeling the two is generally difficult in consideration of the risk of glass cracking, etc.

[0004] As a conventional technique for peeling an adherend from a pressure-sensitive adhesive layer, for example, Patent Document 1 listed below discloses a method for peeling an adhesive laminate in which an adhesive body having at least an adhesive layer containing heat-expandable microparticles is laminated with an adherend, in which the adhesive laminate contains a dye component, and the dye component is irradiated with a laser beam having a wavelength that matches the absorption wavelength of the dye component, and the heat generated thereby expands the heat-expandable microparticles, thereby peeling the adhesive body from the adherend.

[0005] Furthermore, Patent Document 2 listed below discloses a method for manufacturing an electronic composite component, which includes the steps of forming a temporary adhesive layer on a substrate, the temporary adhesive layer containing a material that softens or decomposes when irradiated with light, applying a conductive ink onto the temporary adhesive layer, baking the conductive ink to form a wiring layer, bonding an insulating member onto the wiring layer, and, after the step of bonding the insulating member, irradiating the temporary adhesive layer with light to soften or decompose the temporary adhesive layer, and peeling off the insulating member to which the wiring layer is bonded from the temporary adhesive layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2013-159743 [Patent Document 2] Japanese Patent Application Publication No. 2017-45829 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technique of Patent Document 1 requires scanning a spot-shaped laser beam and irradiating the entire surface of the adhesive with the laser beam, which is a time-consuming process and leaves room for further improvement.

[0008] Specifically, the irradiation of light onto the temporary adhesive layer in Patent Document 2 involves irradiating the entire surface of the temporary adhesive layer with flash light from a xenon flash lamp to soften or decompose the acrylic urethane resin contained in the temporary adhesive layer, thereby peeling the insulating member from the temporary adhesive layer.

[0009] However, in the technology disclosed in Patent Document 2, in order to cause rapid softening or decomposition of the temporary adhesive layer, the temporary adhesive layer must essentially contain 1 wt% or more of carbon black as a flash light absorber. Flash light absorbers such as carbon black have the property of absorbing all visible light, and when optical transparency is required for the laminate, such light absorbers cannot be used in the pressure-sensitive adhesive layer, and a solution is needed.

[0010] Therefore, an object of the present invention is to provide a method for easily peeling an adherend from a pressure-sensitive adhesive layer using high-energy light while maintaining good light transmittance in the visible light region in a laminate having an adherend and a pressure-sensitive adhesive layer. [Means for solving the problem]

[0011] The present invention is as follows. [1] A method for peeling an adherend from a pressure-sensitive adhesive layer by irradiating a laminate in which a pressure-sensitive adhesive layer and an adherend are laminated with light, comprising: The method includes applying a light irradiation dose of 1000 mJ / cm 2 to the pressure-sensitive adhesive layer, the pulse width of which is 1 second or less. 2 The method includes a step of irradiating the light described above, The pressure-sensitive adhesive layer is characterized in that the minimum transmittance in the near-infrared region with a wavelength of 800 nm to 2500 nm and the maximum transmittance in the visible light region with a wavelength of 380 nm to 780 nm, measured using a measurement sample in which 0.7 mm thick alkali-free glass is bonded to one adhesive surface of the pressure-sensitive adhesive layer and the other adhesive surface of the pressure-sensitive adhesive layer, sandwiching the pressure-sensitive adhesive layer therebetween, satisfy the following conditions (1) and (2): (1) The minimum transmittance is 75% or less. (2) The value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more. [2] The peeling method according to [1] above, wherein the light is irradiated multiple times. [3] The peeling method according to the above [1] or [2], wherein the light has a peak top in the near-infrared region of wavelengths of 800 nm to 2500 nm. [4] The light irradiation amount of the light is 1000 mJ / cm 2 ~100,000mJ / cm 2 The peeling method according to any one of the above [1] to [3], [5] The peeling method according to any one of the above [1] to [4], wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive. [6] The peeling method according to any one of the above [1] to [5], wherein the pressure-sensitive adhesive layer contains a near-infrared absorbing material. [7] The peeling method according to [6] above, wherein the near-infrared absorbing material is a near-infrared absorbing dye. [Effects of the Invention]

[0012] According to the present invention, a method can be provided in which, in a laminate in which a pressure-sensitive adhesive layer and an adherend are laminated, the adherend can be easily peeled from the pressure-sensitive adhesive layer using high-energy light while having good light transmittance in the visible light region. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of a laminate for illustrating a peeling method according to one embodiment of the present invention. [Figure 2] FIG. 2 shows the transmission spectra of measurement samples using pressure-sensitive adhesive sheets with a pressure-sensitive adhesive layer thickness of 50 μm in some examples and comparative examples. [Figure 3] FIG. 3 shows the transmission spectra of measurement samples using pressure-sensitive adhesive sheets with a pressure-sensitive adhesive layer thickness of 50 μm in some examples and comparative examples. [Figure 4] FIG. 4 is a diagram showing the transmission spectrum of a measurement sample using a pressure-sensitive adhesive sheet with a pressure-sensitive adhesive layer thickness of 50 μm in a comparative example. [Figure 5] FIG. 5 is a photograph illustrating the light transmittance of the measurement samples used in some of the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. For the sake of convenience, only preferred embodiments of the present invention will be shown below, but it is of course not intended to limit the present invention thereto.

[0015] FIG. 1 is a cross-sectional view of a laminate for illustrating a peeling method according to one embodiment of the present invention.

[0016] In FIG. 1, the laminate 1 in this embodiment is formed by laminating an adherend 12 and an adherend 16 via a pressure-sensitive adhesive layer 14, and by irradiating light onto this laminate 1, the adherend 12 and the adherend 16 are peeled off from the pressure-sensitive adhesive layer 14.

[0017] In this embodiment, the pressure-sensitive adhesive layer 14 is irradiated with light having a pulse width of 1 second or less and a light irradiation amount of 1000 mJ / cm 2 . 2 The adhesive layer 14 is irradiated with the above-described light (also referred to as high-energy light), and is characterized in that the minimum transmittance in the near-infrared region with a wavelength of 800 nm to 2500 nm and the maximum transmittance in the visible light region with a wavelength of 380 nm to 780 nm, measured using a measurement sample in which 0.7 mm thick alkali-free glass is bonded to one adhesive surface of the adhesive layer and the other adhesive surface of the adhesive layer sandwiched between them, satisfy the following conditions (1) and (2): (1) The minimum transmittance is 75% or less. (2) The value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more.

[0018] In the peeling method of the present embodiment, when adherends are laminated on both surfaces of the pressure-sensitive adhesive layer, at least one of the adherends is peeled off. That is, only one of the adherends may be peeled off, or both of the adherends may be peeled off.

[0019] 1 shows an embodiment in which adherends are laminated on both surfaces of the pressure-sensitive adhesive layer, but a substrate, a release sheet, etc. may be provided in place of one of the adherends. In this case, only the other adherend is peeled from the pressure-sensitive adhesive layer 14 by the peeling method of this embodiment.

[0020] Furthermore, the laminate 1 in FIG. 1 has a three-layer structure in which adherend 12, adhesive layer 14, and adherend 16 are laminated together, but since the peeling method of this embodiment can be applied as long as the adhesive layer and the adherend are in at least partial contact, there is no limit to the number of layers, and the laminate may have a total of four or more layers with any other layers interposed.

[0021] <Adhesive layer> The adhesive layer 14 in this embodiment is not particularly limited as long as it satisfies the above conditions (1) and (2). For example, typical examples of adhesives that constitute the adhesive layer include acrylic adhesives, urethane adhesives, and rubber adhesives.

[0022] Among them, acrylic pressure-sensitive adhesives containing acrylic polymers are preferred because of their excellent transparency. Acrylic pressure-sensitive adhesives typically contain a (meth)acrylic polymer as a main component. In this specification, the term "main component" refers to the component with the highest content among all components, for example, a component that accounts for 50% by mass or more of all components.

[0023] The (meth)acrylic polymer may be contained in the pressure-sensitive adhesive composition in an amount of, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more of the solid content of the pressure-sensitive adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as a monomer unit as a main component. Here, (meth)acrylate refers to acrylate and / or methacrylate.

[0024] Examples of alkyl (meth)acrylates that constitute the main skeleton of the (meth)acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms.

[0025] Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. These groups may be used alone or in combination. The average carbon number of these alkyl groups is preferably 3 to 9.

[0026] In addition to the alkyl (meth)acrylate monomer unit, functional group-containing monomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers can be introduced into the (meth)acrylic polymer for the purpose of improving adhesiveness and heat resistance.

[0027] The carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and also contains a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group.

[0028] Specific examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0029] Among the carboxyl group-containing monomers, acrylic acid is preferred from the viewpoints of copolymerizability, cost, and adhesive properties.

[0030] The hydroxyl group-containing monomer is a compound that contains a hydroxyl group in its structure and also contains a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group.

[0031] Specific examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate.

[0032] Among the above hydroxyl group-containing monomers, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred from the viewpoint of durability, and 4-hydroxybutyl (meth)acrylate is particularly preferred.

[0033] The amide group-containing monomer is a compound that contains an amide group in its structure and also contains a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group.

[0034] Specific examples of amide group-containing monomers include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0035] The pressure-sensitive adhesive layer 14 preferably contains a near-infrared absorbing material. In this embodiment, when the high-energy light has a peak top in the near-infrared region of wavelengths of 800 nm to 2500 nm, irradiating the pressure-sensitive adhesive layer 14 with such high-energy light facilitates decomposition or softening of the pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer 14, making it possible to more easily peel the adherend from the pressure-sensitive adhesive layer 14.

[0036] A typical example of the near-infrared absorbing material is a near-infrared absorbing dye. There are no particular limitations on the near-infrared absorbing dye as long as it can absorb light in the near-infrared region with a wavelength of 800 nm to 2500 nm.

[0037] Examples of near-infrared absorbing materials include known cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, immonium dyes, aminoum dyes, quinolium dyes, pyrylium dyes, Ni complex dyes, pyrrolopyrrole dyes, copper complex dyes, quaterrylene dyes, azo dyes, anthraquinone dyes, diimonium dyes, squarylium dyes, porphyrin dyes, etc. Among these, diimonium dyes are preferred.

[0038] In this embodiment, the diimonium dye can be an amorphous diimonium salt represented by the following formula (1).

[0039] [ka]

[0040] In formula (1), R 1 ~R 8 represent monovalent organic groups which may be the same or different, and X - indicates an anion.

[0041] In this specification, an amorphous body refers to a solid state in which atoms or molecules do not form crystals with a regular periodic arrangement. The presence or absence of crystallinity in a solid can be determined by measuring a diffraction pattern using a powder X-ray diffractometer. In other words, an amorphous body is a state in which no clear diffraction peaks indicating crystallinity are detected in the diffraction pattern obtained using a powder X-ray diffractometer.

[0042] For example, when diffraction peaks are measured using a powder X-ray diffractometer, the half-width of the peak with the maximum intensity detected when the peak top is taken from the baseline is 2θ=1° or more. Such a solid does not substantially contain crystals and is composed only of an amorphous body.

[0043] By using an amorphous form of diimonium salt (1) as a near-infrared absorbing dye, when it is contained in the adhesive layer 14, it has the characteristics of high heat resistance, high moist heat resistance, and excellent transparency, compared to a crystalline state such as a crystal or an aggregate.

[0044] R 1 ~R 8 Preferred organic groups include linear or branched C groups optionally substituted with halogen atoms. 1-10 Alkyl groups of C 3-12 cycloalkyl group, cycloalkyl ring optionally substituted C 3-12 Cycloalkyl-C 1-10 Examples of the alkyl group include the alkyl groups shown below.

[0045] Linear or branched C 1-10 Examples of alkyl groups include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-amyl group, an isoamyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 2-dimethylpropyl group, and a 1,1-dimethylpropyl group.

[0046] Among these, n-propyl, n-butyl, n-pentyl, and n-hexyl groups are preferred because they reduce the crystallinity of the diimonium salt (1) and make it more likely to become amorphous. Furthermore, the presence of such low-polarity alkyl groups makes the diimonium salt (1) more likely to have a polarity similar to that of the acrylic pressure-sensitive adhesive, making it easier to mix with the acrylic pressure-sensitive adhesive.

[0047] C 3-12 Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group.

[0048] C 3-12 Cycloalkyl-C 1-10 The alkyl group may be substituted or unsubstituted on the cycloalkyl ring. Substituents that may be substituted include alkyl groups, hydroxyl groups, sulfonic acid groups, alkylsulfonic acid groups, nitro groups, amino groups, alkoxy groups, halogenated alkyl groups, and halogen atoms. Unsubstituted groups are preferred, and cycloalkyl-alkyl groups represented by the following general formula (3) are preferred because they have low solubility in acrylic pressure-sensitive adhesives.

[0049] [ka]

[0050] In the above general formula (3), A represents a linear or branched alkyl group having 1 to 10 carbon atoms, and m represents an integer of 3 to 12. The number of carbon atoms in A is preferably 1 to 4. Furthermore, m is preferably 5 to 8, and particularly preferably 5 or 6.

[0051] Specific examples of the cycloalkyl-alkyl group of the general formula (3) include a cyclopentylmethyl group, a 2-cyclopentylethyl group, a 2-cyclopentylpropyl group, a 3-cyclopentylpropyl group, a 4-cyclopentylbutyl group, a 2-cyclohexylmethyl group, a 2-cyclohexylethyl group, a 3-cyclohexylpropyl group, and a 4-cyclohexylbutyl group. Among these, a cyclopentylmethyl group, a cyclohexylmethyl group, a 2-cyclohexylethyl group, a 2-cyclohexylpropyl group, a 3-cyclohexylpropyl group, and a 4-cyclohexylbutyl group are preferred.

[0052] The cycloalkyl-alkyl group of the general formula (3) is more preferably a cyclopentylmethyl group or a cyclohexylmethyl group. In particular, the cyclohexylmethyl group is more preferred because it has low solubility in acrylic resins used in adhesives, hard coating resins, etc., and has low polarity.

[0053] Also, linear or branched C substituted with halogen atoms 1-10 Examples of the alkyl group include halogenated alkyl groups such as a 2-halogenoethyl group, a 2,2-dihalogenoethyl group, a 2,2,2-trihalogenoethyl group, a 3-halogenopropyl group, a 3,3-dihalogenopropyl group, a 3,3,3-trihalogenopropyl group, a 4-halogenobutyl group, a 4,4-dihalogenobutyl group, a 4,4,4-trihalogenobutyl group, a 5-halogenopentyl group, a 5,5-dihalogenopentyl group, and a 5,5,5-trifluoropentyl group. Among these, a monohalogenated alkyl group represented by the following general formula (4) is preferred.

[0054] -C n H 2n -CH2Y (4) In the above general formula (4), n represents an integer of 1 to 9, and Y represents a halogen atom.

[0055] n is preferably 1 to 4. Furthermore, it is particularly preferable that Y is a fluorine atom. Specific examples of the monohalogenated alkyl group represented by the above general formula (4) include monofluoroalkyl groups such as a 2-fluoroethyl group, a 3-fluoropropyl group, a 4-fluorobutyl group, and a 5-fluoropentyl group.

[0056] R in general formula (1) 1 ~R 8 may all be the same monovalent organic group, or may be two or more different monovalent organic groups, preferably two different monovalent organic groups. 1 and R 2 , R 3 and R 4 , R 5 and R 6 , and R 7 and R 8 In other words, a diimonium salt (1) in which the two monovalent organic groups in each amino group are a combination of two different monovalent organic groups is preferred.

[0057] The two monovalent organic groups are preferably a combination of monovalent organic groups selected from the group consisting of n-propyl, n-butyl, n-pentyl, n-hexyl, and cyclohexylmethyl. More preferably, one monovalent organic group is a cyclohexylmethyl group, and the other monovalent organic group is a monovalent organic group selected from the group consisting of n-propyl, n-butyl, n-pentyl, and n-hexyl.

[0058] When the monovalent organic group of one amino group is a combination of two different monovalent organic groups, the crystallinity of the diimonium salt (1) is reduced and it is likely to become an amorphous substance. In particular, when one of the two monovalent organic groups is a cyclohexylmethyl group, the crystallinity is reduced due to steric hindrance, making it more likely to become an amorphous substance, which is preferable.

[0059] X in general formula (1) -is an anion necessary to neutralize the charge of the diimonium cation, and an organic acid anion, an inorganic anion, etc. can be used.

[0060] Specific examples of the anion include halogen ions such as a fluorine ion, a chlorine ion, a bromine ion, and an iodine ion, as well as perchlorate ions, periodate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, bis(trifluoromethanesulfonyl)imidate ions, and bis(fluorosulfonyl)imidate ions.

[0061] Among these, tetrafluoroborate ion, hexafluorophosphate ion, hexafluoroantimonate ion, bis(trifluoromethanesulfonyl)imidate ion, and bis(fluorosulfonyl)imidate ion are particularly preferably used as the anion, because they can improve the heat resistance, moist heat resistance, etc. of the resulting pressure-sensitive adhesive layer.

[0062] In particular, hexafluorophosphate ion, hexafluoroantimonate ion, and bis(fluorosulfonyl)imidate ion are preferred because they are highly inorganic and the resulting diimonium salts have low solubility in acrylic pressure-sensitive adhesives.

[0063] Specific examples of the diimonium salt (1) include N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium hexafluorophosphate, N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium hexafluoroantimonate, N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium bis(trifluoromethanesulfonyl)imidate, and bis(fluorosulfonyl)imimonium. N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium hexafluorophosphate, N,N,N',N'-tetrakis{p-di(n-propyl)aminophenyl}-p-phenylenedimonium hexafluoroantimonate, N,N,N',N'-tetrakis{p-di(n-propyl)aminophenyl}-p-phenylenedimonium bis(trifluoromethanesulfonyl)imidate, N,N,N',N'-tetrakis{p-di(n-propyl)aminophenyl}-p-phenylenedimonium bis(trifluoromethanesulfonyl)imidate Nylene diimmonium, bis(fluorosulfonyl)imidate-N,N,N',N'-tetrakis{p-di(n-propyl)aminophenyl}-p-phenylenedimonium, hexafluorophosphate-N,N,N',N'-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylenedimonium, hexafluoroantimonate-N,N,N',N'-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylenedimonium, bis(trifluoromethanesulfonyl)imidate-N,N,N',N'-tetrakis{p-di(n -butyl)aminophenyl}-p-phenylenedimonium, bis(fluorosulfonyl)imidate-N,N,N',N'-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylenedimonium, hexafluoroantimonate-N,N,N',N'-tetrakis{p-di(n-pentyl)aminophenyl}-p-phenylenedimonium, bis(fluorosulfonyl)imidate-N,N,N',N'-tetrakis{p-di(n-pentyl)aminophenyl}-p-phenylenedimonium, hexafluorophosphate-N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-propyl)aminophenyl}-p-phenylenedimonium, bis(fluorosulfonyl)imidic acid-N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-propyl)aminophenyl}-p-phenylenedimonium, hexafluorophosphate-N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-butyl)aminophenyl}-p-phenylenedimonium, bis(fluorosulfonyl)imidic acid-N,N,N', N'-tetrakis{p-(cyclohexylmethyl-n-butyl)aminophenyl}-p-phenylenedimonium, N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-pentyl)aminophenyl}-p-phenylenedimonium hexafluorophosphate, and N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-pentyl)aminophenyl}-p-phenylenedimonium bis(fluorosulfonyl)imidate are preferred because of their excellent heat resistance, moist heat resistance, and transparency.

[0064] Among these, particularly preferred are N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium hexafluorophosphate, N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium bis(trifluoromethanesulfonyl)imidate, N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium bis(fluorosulfonyl)imidate, N,N,N',N'-tetrakis{p-di(cyclohexylmethyl)aminophenyl}-p-phenylenedimonium hexafluorophosphate, and N,N,N',N'-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylenedimonium hexafluoroantimonate. )aminophenyl}-p-phenylenedimonium, bis(fluorosulfonyl)imidate-N,N,N',N'-tetrakis{p-di(n-butyl)aminophenyl}-p-phenylenedimonium, hexafluoroantimonate-N,N,N',N'-tetrakis{p-di(n-pentyl)aminophenyl}-p-phenylenedimonium, hexafluorophosphate-N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-propyl)aminophenyl}-p-phenylenedimonium, and hexafluorophosphate-N,N,N',N'-tetrakis{p-(cyclohexylmethyl-n-butyl)aminophenyl}-p-phenylenedimonium are preferred in that they have low crystallinity and are more likely to become amorphous.

[0065] The diimonium dye used in this embodiment is obtained by dry-milling a crystalline solid of diimonium salt (1) to form an amorphous substance. The crystalline solid of diimonium salt (1) can be produced by a conventionally known method, for example, the method described in WO 2011 / 074619. Furthermore, the amorphization of the crystalline solid of diimonium salt (1) by dry-milling may also be carried out by the method described in WO 2011 / 074619.

[0066] As the diimonium dye, commercially available products such as CIR-RL (bis(trifluoromethanesulfonyl)imide salt) and CIR-FS265 manufactured by Nippon Carlit Co., Ltd. may be used.

[0067] The adhesive layer 14 may contain, as the diimonium dye, one type of amorphous diimonium salt (1) alone or a combination of two or more types.

[0068] The content of the near-infrared absorbing dye in the adhesive layer 14 is, for example, 50% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 2% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, relative to 100% by mass of the adhesive composition for forming the adhesive layer 14.

[0069] The content of the near-infrared absorbing dye in the pressure-sensitive adhesive layer 14 is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass or more, relative to 100% by mass of the pressure-sensitive adhesive composition.

[0070] Furthermore, the adhesive layer 14 may contain a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator.

[0071] The thermal polymerization initiator is not particularly limited, but for example, an azo-based polymerization initiator, a peroxide-based initiator, a redox-based initiator formed by combining a peroxide with a reducing agent, a substituted ethane-based initiator, etc. can be used.

[0072] More specifically, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxye persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; and redox initiators such as a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate.

[0073] The photopolymerization initiator is not particularly limited, but examples thereof include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

[0074] Specifically, examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.).

[0075] Examples of the α-hydroxyketone photopolymerization initiator include 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name "Darocur 1173", manufactured by BASF Japan Ltd.), and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name "Irgacure 2959", manufactured by BASF Japan Ltd.).

[0076] Examples of α-aminoketone photopolymerization initiators include 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name "Irgacure 907", manufactured by BASF Japan Ltd.), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name "Irgacure 369", manufactured by BASF Japan Ltd.), and the like.

[0077] Examples of acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name "Lucirin TPO", manufactured by BASF Japan Ltd.).

[0078] Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl ether.

[0079] Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-t-butyl-dichloroacetophenone.

[0080] Examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride.

[0081] Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime.

[0082] Examples of the benzoin-based photopolymerization initiator include benzoin.

[0083] Examples of the benzyl-based photopolymerization initiator include benzyl.

[0084] Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone.

[0085] An example of the ketal-based photopolymerization initiator is benzyl dimethyl ketal.

[0086] Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0087] The content of the polymerization initiator in the pressure-sensitive adhesive layer 14 varies depending on the type of the initiator and is not particularly limited. For example, when an acrylic pressure-sensitive adhesive composition is used, the content of the polymerization initiator is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 5 parts by weight, and even more preferably 0.05 to 3 parts by weight, per 100 parts by mass of the (meth)acrylic polymer.

[0088] In addition, the adhesive layer 14 may also contain a multifunctional monomer containing a monomer having two or more ethylenically unsaturated bonds in the molecule, from the viewpoint of adjusting its elasticity and flexibility, increasing cohesive strength and improving adhesive strength, etc.

[0089] Examples of polyfunctional monomers include trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, poly Examples include ethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, and reactive hyperbranched polymers having multiple (meth)acryloyl groups at the terminals (for example, trade names "CN2300", "CN2301", and "CN2320" manufactured by SARTOMER).

[0090] There are no particular limitations on the content of the polyfunctional monomer in the pressure-sensitive adhesive layer 14. For example, when an acrylic pressure-sensitive adhesive composition is used, the content of the polyfunctional monomer is, for example, 0.001 to 5 parts by weight, preferably 0.001 to 3 parts by weight, and more preferably 0.001 to 1 part by weight, relative to 100 parts by mass of the (meth)acrylic polymer.

[0091] If necessary, various known additives may be added to the adhesive layer 14 within the range that does not impair the effects of the present invention.

[0092] Examples of additives include crosslinking agents such as isocyanate-based crosslinking agents and epoxy-based crosslinking agents; tackifiers such as rosin derivative resins, polyterpene resins, petroleum resins, and oil-soluble phenolic resins; plasticizers; fillers; antioxidants; surfactants; chain transfer agents; etc. The additives may be contained alone or in combination of two or more.

[0093] The thickness of the adhesive layer 14 is not particularly limited, but in order to achieve both reliability and releasability in the adhesive layer 14, it is preferably 5000 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, even more preferably 250 μm or less, even more preferably 100 μm or less, even more preferably 50 μm or less, even more preferably 25 μm or less, and particularly preferably 10 μm or less.

[0094] The thickness of the pressure-sensitive adhesive layer 14 is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and particularly preferably 8 μm or more. The pressure-sensitive adhesive layer 14 may have a single-layer structure or a multilayer structure.

[0095] The adhesive layer 14 is formed by applying an adhesive composition to an adherend to obtain an adhesive composition layer, and then drying or curing the adhesive composition layer (e.g., curing by heat or active energy rays) as necessary.

[0096] The application, drying, and curing can be carried out according to a conventional method. For example, the pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

[0097] On the other hand, as shown in the examples below, the adhesive layer 14 may be formed by providing an adhesive composition layer on a substrate as described above, laminating a release-treated release liner to form an adhesive sheet, and after storage as necessary, peeling off the release liner during production, and bonding the adhesive sheet to the adherend.

[0098] The adhesive layer 14 in this embodiment is characterized in that the minimum transmittance in the near-infrared region with a wavelength of 800 nm to 2500 nm and the maximum transmittance in the visible light region with a wavelength of 380 nm to 780 nm, measured using a measurement sample formed by bonding 0.7 mm thick alkali-free glass to one adhesive surface of the adhesive layer and the other adhesive surface of the adhesive layer, with the adhesive layer sandwiched between them, satisfy the following conditions (1) and (2): (1) The minimum transmittance is 75% or less. (2) The value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more.

[0099] In other words, the measurement sample is one in which the adhesive layer 14 is sandwiched between alkali-free glass sheets having a thickness of 0.7 mm.

[0100] If the minimum transmittance exceeds 75%, the high-energy light is not absorbed by the pressure-sensitive adhesive layer 14, making it difficult to peel the adherend from the pressure-sensitive adhesive layer 14.

[0101] The minimum transmittance is preferably 70% or less, more preferably 68% or less, even more preferably 65% or less, even more preferably 63% or less, even more preferably 60% or less, even more preferably 58% or less, even more preferably 55% or less, even more preferably 53% or less, even more preferably 50% or less, even more preferably 45% or less, and particularly preferably 40% or less. The minimum transmittance is, for example, 0.000001% or more.

[0102] Furthermore, if the value obtained by dividing the maximum transmittance by the minimum transmittance is less than 1.15, high-energy light will be difficult to absorb into the adhesive layer 14, making it difficult to peel the adherend from the adhesive layer, and the adhesive layer will not be easily peeled off by high-energy light despite having good light transmittance in the visible light region.

[0103] The value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more, preferably 1.20 or more, more preferably 1.25 or more, even more preferably 1.30 or more, still more preferably 1.35 or more, still more preferably 1.40 or more, still more preferably 1.50 or more, still more preferably 1.7 or more, still more preferably 2 or more, still more preferably 3 or more, and particularly preferably 5 or more. The value obtained by dividing the maximum transmittance by the minimum transmittance is, for example, 10,000 or less, 5,000 or less.

[0104] The maximum transmittance is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, still more preferably 50% or more, still more preferably 60% or more, still more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more. The maximum transmittance is, for example, 99.9% or less, 98% or less.

[0105] The maximum transmittance and the minimum transmittance in the pressure-sensitive adhesive layer 14 are measured using the above-mentioned measurement sample, specifically by the method described in the examples.

[0106] The condition (1) can be satisfied, for example, by setting the content of the near-infrared absorbing dye in the pressure-sensitive adhesive layer 14 as described above.

[0107] Furthermore, the condition (2) can be satisfied by setting the content of the near-infrared absorbing dye in the adhesive layer 14 as described above, and by not including a material that absorbs light in the visible light region with wavelengths of 380 nm to 780 nm, such as carbon black, in the adhesive layer 14, or by including a small amount of such material so as to satisfy the condition (2).

[0108] <Adherend> Examples of the adherend used in this embodiment include resins, glass, silicon wafers, inorganic materials, and metal materials that are capable of transmitting high-energy light. As shown in Figure 1, when there are two or more types of adherends, they may be the same material or different materials. Furthermore, as long as the high-energy light reaches the pressure-sensitive adhesive layer 14, at least one of the adherends may be made of a material that is not capable of transmitting high-energy light.

[0109] Examples of resins in the adherend include transparent resins made of homopolymers or copolymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate (PC), cycloolefin polymer (COP), polystyrene, polypropylene (PP), polyethylene, polycycloolefin, polyurethane, polyimide, acrylic (PMMA), and ABS.

[0110] Examples of glass for the adherend include alkali-free glass, soda glass, borosilicate glass, and aluminosilicate glass.

[0111] Examples of inorganic materials for the adherend include inorganic bulk materials and inorganic thin films, and inorganic thin films are preferred from the viewpoint of light transmittance. Examples of inorganic thin films include carbon-based thin films such as graphite and graphene, and nitride-based thin films such as boron nitride.

[0112] The inorganic thin film has a thickness of, for example, 0.3 nm or more, 1 nm or more, or 3 nm or more, and a thickness of, for example, 10 μm or less, 5 μm or less, or 1 μm or less.

[0113] From the viewpoint of optical transparency, a metal thin film is preferably used as the metal material for the adherend, such as a metal oxide thin film made of ITO, Al2O3, ZnO, or SiO, or a metal nitride thin film made of SiN.

[0114] The metal thin film has a thickness of, for example, 1 nm or more, 3 nm or more, or 5 nm or more, and a thickness of, for example, 10 μm or less, 5 μm or less, or 1 μm or less.

[0115] Among these, glass, resin and silicon wafer are preferred as adherends because they allow peeling of the adhesive layer from a rigid body, which has been difficult to achieve in the past, and are resistant to heating by high-energy light.

[0116] The thickness of the adherend can be set appropriately depending on the application, but from the viewpoint of the reach of high-energy light to the pressure-sensitive adhesive layer 14, it is, for example, 100 mm or less, preferably 50 mm or less, more preferably 10 mm or less, even more preferably 5 mm or less, even more preferably 3 mm or less, even more preferably 1 mm or less, and particularly preferably 0.5 mm or less.

[0117] The lower limit of the thickness of the adherend is preferably 1 μm or more for films, and 0.1 mm or more, more preferably 0.3 mm or more, for glass.

[0118] Although the laminate 1 shown in FIG. 1 has a planar shape as the adherend, the present invention is not limited to this form, and the shape of the adherend can be freely changed depending on the application as long as the high-energy light reaches the pressure-sensitive adhesive layer 14.

[0119] <Light irradiation process> In the peeling method of this embodiment, the pressure-sensitive adhesive layer is irradiated with light having a pulse width of 1 second or less and a light irradiation dose of 1000 mJ / cm 2 . 2 The method includes a step of irradiating the adhesive layer with light as described above. Since the light is high-energy and short-pulse light, the adhesive layer to be irradiated is decomposed or softened, thereby enabling the adherend to be peeled off from the adhesive layer.

[0120] The light applied in this step preferably includes multiple continuous wavelength bands.

[0121] The pulse width of the light applied in this step is preferably 0.5 seconds or less, more preferably 0.1 seconds or less, even more preferably 0.05 seconds or less, still more preferably 0.01 seconds or less, and particularly preferably 0.001 seconds (1000 μs) or less.

[0122] The number of light pulses irradiated in this step may be one or more. The number of light pulses irradiated in this step may be, for example, 2 or more, 3 or more, 5 or more, 10 or more, 100 or more, 1,000 or more, 10,000 or more, 100,000 or more, 1 million or more, or 10 million or more. Furthermore, the number of light pulses irradiated in this step may be 10 billion or less, 1 billion or less, 100 million or less, or 10 million or less.

[0123] Here, the number of pulses of light irradiated in this process means the number of pulses contained in one irradiation of light if the number of times of light irradiation is one, and means the total number of pulses contained in the multiple irradiations of light if the number of times of light irradiation is multiple.

[0124] The exposure time to light used in this step is preferably 10 μs or more, more preferably 50 μs or more, even more preferably 100 μs or more, still more preferably 1000 μs or more, and particularly preferably 10,000 μs or more.

[0125] The exposure time to light used in this step is preferably 100 seconds or less, more preferably 50 seconds or less, even more preferably 30 seconds or less, and particularly preferably 10 seconds or less.

[0126] Here, the exposure time means the exposure time for one irradiation of light. That is, when one irradiation of light contains one pulse, the exposure time is equal to the pulse width. When one irradiation of light contains multiple pulses, the exposure time is equal to the sum of the pulse width and the pulse interval.

[0127] The number of times of light irradiation used in this step may be one or more. The number of times of light irradiation used in this step may be, for example, two or more, three or more, five or more, or ten or more. Furthermore, the number of times of light irradiation used in this step may be, for example, 100 or less, 80 or less, or 50 or less.

[0128] Furthermore, the number of pulses contained in one irradiation of light may be one or more. The number of pulses contained in one irradiation of light may be, for example, 2 or more, 3 or more, 5 or more, 10 or more, 100 or more, 1000 or more, 10,000 or more, 100,000 or more, 1 million or more, or 10 million or more. The number of pulses contained in one irradiation of light may be, for example, 10 billion or less, 1 billion or less, 100 million or less, or 10 million or less.

[0129] From the viewpoint of enabling the adherend to be more easily peeled from the pressure-sensitive adhesive layer 14, the light used in this step preferably has a peak top in the near-infrared region with a wavelength of 800 nm to 2500 nm, and more preferably has a peak top in the near-infrared region with a wavelength of 800 nm to 1500 nm.

[0130] In addition, from the viewpoint of enabling the adherend to be more easily peeled from the pressure-sensitive adhesive layer 14, the light irradiation amount of the light applied in this step is set to 1000 mJ / cm 2 2 ~100,000mJ / cm 2 The light irradiation dose of the light applied in this step is preferably 2000 mJ / cm. 2 More than 3000mJ / cm is preferable. 2 More preferably, 4000mJ / cm 2 More preferably, 5000 mJ / cm or more 2 More preferably, 7000 mJ / cm or more 2 More preferably, 10,000 mJ / cm or more 2 More preferably, 30,000 mJ / cm or more 2 More preferably, 50,000 mJ / cm or more 2 The above is particularly preferred.

[0131] As the light irradiation method used in this step, for example, a known flash lamp annealing method can be used.

[0132] In the flash lamp annealing method of this embodiment, for example, a xenon lamp is used as a lamp, and light having a peak top in the near-infrared region of wavelengths of 800 nm to 2500 nm is irradiated with a pulse width of 1 second or less and an intensity of 1000 mJ / cm . 2 ~100,000mJ / cm 2 This method involves irradiating the adhesive layer 14 with a light irradiation dose of 1000 kJ / cm, heat-treating the adhesive layer 14 for a short period of time, and decomposing or softening the adhesive contained in the adhesive layer 14.

[0133] Furthermore, the flash lamp annealing method allows for the irradiation of a wide area at once. In principle, the irradiation area can be increased by increasing the lamp size or the number of lamps, so there is no limit to the irradiation area.

[0134] The irradiation area is, for example, 1 cm 2 More than 5cm 2 More than 10cm 2 More than 30cm 2 More than 50cm 2 More than 100cm 2 More than 300cm 2 More than 500cm 2 More than 1000cm 2 or more than 10,000 cm 2 The irradiation area is, for example, 1,000,000 cm 2 The following is the result.

[0135] The flash lamp annealing method in this embodiment can be performed using a commercially available device, for example, a batch-type flash lamp irradiation device (PulseForge 1300 X2 lamp, manufactured by NovaCentrix).

[0136] The flash lamp annealing method is preferable because the light irradiation time is very short, and therefore materials that do not absorb light, such as glass, are not heated. In addition, in principle, there is no limit to the area of the adherend and the pressure-sensitive adhesive layer, making it possible to irradiate a wide area with light at once, which is preferable.

[0137] <Application> The peeling method of the present embodiment is suitable for use in peeling bonds in various fields such as automobiles, machine parts, electrical appliances, and building materials (for example, peeling bonds between parts, peeling bonds between parts and housings, etc.).

[0138] In particular, the peeling method of the present embodiment is suitably used for peeling bonds that require recycling or rework, and as a processing material in material manufacturing processes for semiconductor processing materials, glass masking materials, carrier tapes, paint protection materials, etc. The peeling method is particularly suitably used for peeling bonds between expensive electronic components, such as liquid crystal panels, plasma panels, or organic EL panels, and their frames.

[0139] In particular, the peeling method of this embodiment has high transmittance in the visible light region, and is therefore particularly suitable for use in applications where optical transparency is required. The use of the peeling method of this embodiment is not limited to the above-mentioned use. [Example]

[0140] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the examples, "parts" means parts by mass.

[0141] (Preparation of adhesive layer) A reaction vessel equipped with a condenser, a nitrogen inlet pipe, a thermometer, and a stirrer was charged with 65 parts of butyl acrylate (BA), 15 parts of N-vinylpyrrolidone (NVP), and 20 parts of 4-hydroxybutyl acrylate (4HBA) as monomer components, 0.1 parts of α-thioglycerol as a chain transfer agent, and 122 parts of ethyl acetate as a polymerization solvent. 0.2 parts of 2,2′-azobisisobutyronitrile (AIBN) was then added as a thermal polymerization initiator, and solution polymerization was carried out under a nitrogen atmosphere to obtain a solution containing an acrylic polymer.

[0142] To the resulting acrylic polymer-containing solution, 2 parts of dipentaerythritol hexaacrylate (DPHA), 0.2 parts of Omnirad (Irgacure) 184, and 0.1 parts of Takenate D110N manufactured by Mitsui Chemicals, Inc. were added to obtain a base adhesive. To 100 parts of this base adhesive, a diimonium-based near-infrared absorbing dye, such as the aforementioned CIR-RL or CIR-FS265 manufactured by Nippon Carlit Co., Ltd., or carbon black (Denka Black 100% Press manufactured by Denka Co., Ltd.), was added in the proportions shown in Table 1, followed by degassing to obtain various acrylic adhesive compositions. In Table 1, "-" indicates that the component was not contained.

[0143] Each of the obtained acrylic pressure-sensitive adhesive compositions was applied using an applicator onto a 38 μm-thick polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "MRF#38") whose one side had been treated with silicone for release, so that the thickness when dried would be 50 μm, to form a coating layer.

[0144] The coating layer was then placed in a dryer at 130°C for 3 minutes to dry, and after removal from the dryer, a 38 μm thick polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "MRE#38") with one side treated with silicone for release was coated onto the coating layer so that the release-treated side faced the coating layer, thereby obtaining various adhesive sheets with a thickness of 50 μm as the adhesive layer (adhesive layer thickness 50 μm). Additionally, various adhesive sheets each having an adhesive layer thickness of 150 μm (adhesive layer thickness: 150 μm) were also prepared using the same procedure as above.

[0145] (Minimum and maximum transmittance measurements) In this embodiment, the minimum transmittance in the near-infrared region with wavelengths of 800 nm to 2500 nm and the maximum transmittance in the visible light region with wavelengths of 380 nm to 780 nm were measured as follows.

[0146] The release liner on one side of each of the obtained pressure-sensitive adhesive sheets was peeled off, and the sheet was attached to alkali-free glass (Corning Eagle XG, size: 45 mm x 50 mm x thickness 0.7 mm) with a hand roller. The release liner on the other side was then peeled off, and the sheet was attached to another sheet of alkali-free glass similar to the above with a hand roller. The obtained test pieces were autoclaved at 50°C, 5 atmospheres, and 15 minutes to bond the adhesive layer to the glass. The test pieces were irradiated with a high-pressure mercury lamp at a UVA equivalent of 3000 mJ / cm. 2 The adhesive layer was post-cured by irradiating it with light of 1000 nm, and a measurement sample was obtained. The transmittance spectrum of this sample was then measured using a UV-Vis-Infrared Spectrophotometer UH-4150 (Hitachi High-Tech) with a wavelength range of 380 nm to 2500 nm, a step width of 1 nm, and an integrating sphere unit, using air as the background. From the obtained spectrum, the minimum transmittance (Tmin) in the near-infrared region (wavelengths of 800 nm to 2500 nm) and the maximum transmittance (Tmax) in the visible light region (wavelengths of 380 nm to 780 nm) were calculated.

[0147] The results are shown in Table 1. Figures 2 to 4 show transmission spectra of measurement samples using pressure-sensitive adhesive sheets with a pressure-sensitive adhesive layer thickness of 50 μm in some of the Examples and Comparative Examples shown in Table 1. Figure 2 shows transmission spectra when the near-infrared absorbing dye is CIR-RL (trade name) manufactured by Nippon Carlit Co., Ltd. Figure 3 shows transmission spectra when the near-infrared absorbing dye is CIR-FS265 (trade name) manufactured by Nippon Carlit Co., Ltd. Figure 4 shows transmission spectra when carbon black is used as the dye.

[0148] (Peeling of adherend from adhesive layer using flash lamp annealing method) The various adhesive sheets obtained above were cut into pieces measuring 100 mm x 70 mm, the release liner on one side of each adhesive sheet was peeled off, and the sheets were attached to Corning Gorilla Glass 3 (size: 120 mm x 75 mm x thickness 0.7 mm) with a hand roller. Next, the release liner on the other side was peeled off, and the sheets were attached to another sheet of the same Gorilla Glass with a hand roller. The obtained test pieces were autoclaved at 50°C, 5 atmospheres, and 15 minutes to bond the adhesive layer to the glass. The test pieces were irradiated with a high-pressure mercury lamp at a UVA equivalent of 3000 mJ / cm. 2 The adhesive was post-cured by irradiating it with light.

[0149] This test piece was subjected to a batch-type flash lamp irradiation device (NovaCentrix, PulseForge 1300 X2 lamp) with a lamp irradiation area of 150 mm x 75 mm, lamp height of 10 mm, applied voltage of 600 V, pulse width of 3000 μs, and light irradiation dose of 17000 mJ / cm. 2 The specimen was irradiated once with xenon flash light under the condition of a lamp irradiation time (exposure time) of 0.003 seconds. The peak wavelength of the xenon flash light is 880 nm. After irradiation with flash light, if the glass of the test piece and the adhesive layer were peeled off, the releasability upon light irradiation was evaluated as ◯, and if no peeling occurred, the releasability upon light irradiation was evaluated as ×. The results are shown in Table 1.

[0150] [Table 1]

[0151] From the results in Table 1, in each example, the pressure-sensitive adhesive layer was exposed to light with a pulse width of 1 second or less and a light irradiation dose of 1000 mJ / cm 2 When the adhesive layer was irradiated with light having the above-mentioned properties, it satisfied all of the following conditions: (1) the minimum transmittance is 75% or less; and (2) the value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more. Therefore, the peelability upon light irradiation was good.

[0152] On the other hand, Comparative Examples 1 to 3 did not satisfy either of the conditions (1) and (2), and therefore the peelability upon light irradiation was evaluated as x. Comparative Examples 4 and 5 showed good results in terms of peelability when irradiated with light, but because carbon black was used as the pigment, the pressure-sensitive adhesive sheets had poor light transmittance in the visible light region.

[0153] 5(a) is a plan view (photograph) of a measurement sample using a pressure-sensitive adhesive sheet with a pressure-sensitive adhesive layer thickness of 50 μm, which was used in Examples 1 and 2 and Comparative Examples 4 and 5. The measurement samples of Comparative Examples 4 and 5, which used carbon black, were blackened, whereas the measurement samples of Examples 1 and 2 were slightly colored but showed good light transmittance in the visible light region.

[0154] Figure 5(b) shows an example in which a piece of paper with printed text was placed below each measurement sample. Even with reference to Figure 5(b), the difference in light transmittance in the visible light range between the measurement samples of the example and comparative example was clear.

[0155] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0156] This application is based on a Japanese patent application (Patent Application No. 2020-175486) filed on October 19, 2020, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0157] 1. Laminate 12, 16 Adherent 14 Adhesive layer

Claims

1. A method for peeling an adherend from a pressure-sensitive adhesive layer by irradiating a laminate in which a pressure-sensitive adhesive layer and an adherend are laminated with light, comprising: The method includes applying a light irradiation dose of 1000 mJ / cm to the pressure-sensitive adhesive layer, the pulse width of which is 1 second or less. ２ The method includes a step of irradiating the light described above, the light has a peak top in a near-infrared region of wavelengths of 800 nm to 2500 nm, The pressure-sensitive adhesive layer has a minimum transmittance in the near-infrared region with a wavelength of 800 nm to 2500 nm and a maximum transmittance in the visible light region with a wavelength of 380 nm to 780 nm, which are measured using a measurement sample in which alkali-free glass with a thickness of 0.7 mm is bonded to one adhesive surface of the pressure-sensitive adhesive layer with the pressure-sensitive adhesive layer sandwiched between the other adhesive surface. The minimum transmittance and maximum transmittance satisfy the following conditions (1) and (2): (1) The minimum transmittance is 75% or less. (2) The value obtained by dividing the maximum transmittance by the minimum transmittance is 1.15 or more.

2. The peeling method according to claim 1 , wherein the light is irradiated multiple times.

3. The light irradiation amount of the light is 1000 mJ / cm ２ ~100000mJ / cm ２ The peeling method according to claim 1 or 2, wherein

4. The peeling method according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.

5. The peeling method according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer contains a near-infrared absorbing material.

6. The peeling method according to claim 5 , wherein the near-infrared absorbing material is a near-infrared absorbing dye.

Images