Adhesive sheets, unit panels, and tiling displays

Abstract

We provide adhesive sheets, unit panels, and tiling displays with good laser-cutting properties. [Solution] An adhesive sheet 1 used in the manufacture of unit panels 2 constituting a tiling display, comprising an adhesive layer 11, wherein the adhesive constituting the adhesive layer 11 is an adhesive containing an epoxy resin or a polyester adhesive. The adhesive containing an epoxy resin is preferably an active energy ray curable adhesive containing an epoxy resin with a Tg of 50°C or higher, an epoxy resin that gives a cured product with a Tg of 25°C or lower, and a cationic polymerization initiator. The polyester adhesive is preferably an adhesive obtained by crosslinking and active energy ray curing an adhesive composition containing a polyester polymer having a reactive functional group, a crosslinking agent, and an active energy ray curable component.

Description

[Technical Field]

[0001] The present invention relates to a tiling display, unit panels constituting the tiling display, and adhesive sheets used in the manufacture of the unit panels. [Background technology]

[0002] In recent years, with the increasing demand for higher resolution displays such as 4K and 8K, there has been a growing need for display devices with larger screens. Furthermore, the use of large-screen display devices for digital signage, such as advertising displays in outdoor locations and public facilities, is also advancing. However, manufacturing large-screen display devices in a single batch leads to reduced yield and increased manufacturing costs. Therefore, tiling displays, which connect multiple unit panels in a tile-like manner, have been proposed to manufacture large-screen display devices at a lower cost (e.g., Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-192977 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, when multiple unit panels are tiled together as described above, brightness unevenness is likely to occur in the gaps between panels, resulting in a decrease in image quality. This problem is particularly pronounced in displays using high-brightness mini-LEDs and micro-LEDs, which are attracting attention as next-generation displays.

[0005] Therefore, in order to minimize the gaps between panels, it is conceivable to laser-cut the edges of the unit panels to form flat edges. However, when the edges of unit panels manufactured using a conventional adhesive layer are laser-cut, a problem arises in which the adhesive seeps out from the edges.

[0006] This invention has been made in view of the above circumstances, and aims to provide an adhesive sheet, a unit panel, and a tiling display with good laser-cutting properties. [Means for solving the problem]

[0007] To achieve the above objective, firstly, the present invention provides an adhesive sheet used in the manufacture of unit panels constituting a tiling display, comprising an adhesive layer, wherein the adhesive constituting the adhesive layer is an adhesive containing epoxy resin or a polyester-based adhesive (Invention 1).

[0008] The adhesive constituting the adhesive layer in the above invention (Invention 1) exhibits a predetermined hardness and cohesive force. Therefore, when the edges of a unit panel having the adhesive layer are laser-cut to form a flat surface, the leakage of the adhesive from the edge surface is suppressed.

[0009] In the above invention (Invention 1), it is preferable that the gel fraction of the adhesive constituting the adhesive layer is 20% or more and 99% or less (Invention 2).

[0010] In the above inventions (Inventions 1 and 2), it is preferable that the adhesive containing the epoxy resin is an active energy ray curable adhesive containing an epoxy resin with a Tg of 50°C or higher, an epoxy resin that gives a cured product with a Tg of 25°C or lower, and a cationic polymerization initiator (Invention 3).

[0011] In the above inventions (Inventions 1 and 2), it is preferable that the polyester adhesive is obtained by crosslinking an adhesive composition containing a polyester polymer having a reactive functional group and a crosslinking agent (Invention 4), and it is more preferable that the polyester adhesive is obtained by crosslinking and curing an adhesive composition containing a polyester polymer having a reactive functional group, a crosslinking agent and an active energy ray curable component (Invention 5).

[0012] In the above inventions (Inventions 1 to 5), it is preferable that the thickness of the adhesive layer is 1 μm or more and 500 μm or less (Invention 6).

[0013] In the above inventions (Inventions 1 to 6), it is preferable that two release sheets are provided to protect the adhesive surface of the adhesive layer, and that the adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets (Invention 7).

[0014] Secondly, the present invention provides a unit panel that constitutes a tiling display, characterized in that it comprises an adhesive layer of the adhesive sheet (Inventions 1 to 7) (Invention 8).

[0015] In the above invention (Invention 8), it is preferable that the end face of the unit panel is laser-cut (Invention 9).

[0016] In the above inventions (inventions 8 and 9), a surface substrate and a light-emitting substrate are provided, and it is preferable that the surface substrate or a laminate having the surface substrate and the light-emitting substrate or a laminate having the light-emitting substrate are bonded together by the adhesive layer (invention 10).

[0017] In the above invention (Invention 10), it is preferable that the light-emitting element of the light-emitting substrate is a mini-LED or a micro-LED (Invention 11).

[0018] Thirdly, the present invention provides a tiling display formed by connecting a plurality of the unit panels (Inventions 8 to 11) (Invention 12).

Advantages of the Invention

[0019] The adhesive sheet, unit panel, and tiling display according to the present invention have good laser cutting processability.

Brief Description of the Drawings

[0020] [Figure 1] The figure is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. [Figure 2] The figure is a cross-sectional view of a unit panel according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described. 〔Adhesive Sheet〕 The adhesive sheet according to the embodiment of the present invention is used for manufacturing a unit panel that constitutes a tiling display. An example of the adhesive sheet according to an embodiment of the present invention is shown in FIG. 1.

[0022] As shown in FIG. 1, the adhesive sheet 1 according to an embodiment of the present invention includes an adhesive layer 11. In this embodiment, the adhesive layer 11 is a single layer and is sandwiched between the release sheets 12a and 12b so as to contact the release surfaces of the two release sheets 12a and 12b.

[0023] Note that the adhesive surface of the adhesive layer in this specification is the surface that contacts and adheres to a desired adherend in the adhesive layer. Also, the release surface of the release sheet in this specification refers to the surface having releasability in the release sheet, and includes both the surface subjected to the release treatment and the surface showing releasability without being subjected to the release treatment.

[0024] The release sheets 12a and 12b described above protect the adhesive layer 11 until the adhesive sheet 1 is used, and are peeled off when the adhesive sheet 1 is used. In the adhesive sheet 1 according to this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

[0025] 1. Components 1-1. Adhesive layer The adhesive constituting the adhesive layer 11 of the adhesive sheet 1 according to this embodiment is an adhesive containing epoxy resin (hereinafter sometimes referred to as "epoxy resin adhesive") or a polyester adhesive. These adhesives exhibit predetermined hardness and cohesive force, so when the edges of a unit panel having the adhesive layer 11 are laser-cut and the edge surface is formed into a flat surface, the leakage of adhesive from the edge surface is suppressed. Thus, the adhesive sheet 1 according to this embodiment has excellent laser-cutting processability. Furthermore, in a tiling display formed by joining together multiple unit panels that have been laser-cut in this manner, there are almost no gaps between the unit panels, thereby achieving uniform brightness and high image quality.

[0026] (1) Epoxy resin adhesive The epoxy resin adhesive is preferably an active energy ray curable adhesive containing an epoxy resin (A) having a glass transition temperature (Tg) (sometimes simply referred to as "Tg" in this specification) of 50°C or higher, an epoxy resin (B) that yields a cured product with a Tg of 25°C or lower, and a cationic polymerization initiator (C). This adhesive exhibits hardness and cohesiveness suitable for laser cutting through active energy ray curing, resulting in superior laser cutting properties. From the perspective of SDGs, the materials constituting the epoxy resin adhesive may include materials with a high biomass content, materials that can be recycled or reused, or recycled or reused materials.

[0027] The epoxy resin (A) has a Tg of 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, particularly preferably 120°C or higher, and even more preferably 140°C or higher. The upper limit of Tg is not particularly limited, but from the viewpoint of coating properties, it is preferably 200°C or lower, more preferably 180°C or lower, particularly preferably 160°C or lower, and even more preferably 155°C or lower. The Tg of epoxy resin (A) can be measured using a differential scanning calorimetry analyzer in accordance with JIS K7121. By using this epoxy resin (A), the adhesive after curing will have suitable hardness and cohesiveness, resulting in better laser cutting processability.

[0028] The weight-average molecular weight (Mw) of epoxy resin (A) is preferably 10,000 to 300,000, particularly preferably 18,000 to 200,000, and even more preferably 26,000 to 100,000. The weight-average molecular weight (Mw) of epoxy resin (A) can be determined by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent and expressing it as a value equivalent to standard polystyrene.

[0029] Phenoxy resin is preferred as the epoxy resin (A). Phenoxy resin can be obtained by reacting difunctional phenols with epihalohydrins to a high molecular weight, or by polyaddition reaction between a difunctional epoxy resin and difunctional phenols.

[0030] For example, phenoxy resins can be obtained by reacting difunctional phenols with epihalohydrins in an inert solvent at a temperature of 40 to 120°C in the presence of alkali metal hydroxides. Alternatively, phenoxy resins can also be obtained by polyaddition reaction of difunctional epoxy resins and difunctional phenols in an organic solvent with a boiling point of 120°C or higher, such as an amide solvent, ether solvent, ketone solvent, lactone solvent, or alcohol solvent, at a reaction solids content of 50% by weight or less, while heating at 50 to 200°C in the presence of a catalyst such as an alkali metal compound, organophosphorus compound, or cyclic amine compound.

[0031] Difunctional phenols are not particularly limited as long as they are compounds having two phenolic hydroxyl groups. Examples include monocyclic difunctional phenols such as hydroquinone, 2-bromohydroquinone, resorcinol, and catechol; bisphenols such as bisphenol A, bisphenol F, bisphenol AD, and bisphenol S; dihydroxybiphenyls such as 4,4'-dihydroxybiphenyl; dihydroxyphenyl ethers such as bis(4-hydroxyphenyl) ether; and compounds in which linear alkyl groups, branched alkyl groups, aryl groups, methylol groups, allyl groups, cyclic aliphatic groups, halogens (such as tetrabromobisphenol A), nitro groups, etc. are introduced to the aromatic ring of the phenol skeleton; and polycyclic difunctional phenols in which linear alkyl groups, branched alkyl groups, allyl groups, substituted allyl groups, cyclic aliphatic groups, alkoxycarbonyl groups, etc. are introduced to the carbon atom in the center of the bisphenol skeleton.

[0032] Examples of epihalohydrins include epichlorhydrin, epibromhydrin, and epiiodohydrin.

[0033] Commercially available phenoxy resins can also be used. Examples include Mitsubishi Chemical's product names YX7200 (Tg: 150℃) and YX6954 (bisphenol acetophenone skeleton-containing phenoxy resin, Tg: 130℃), and Nippon Steel Chemical & Material's product name YP70 (Tg: 70℃).

[0034] Furthermore, epoxy resin (A) can be used alone or in combination of two or more types.

[0035] The epoxy resin (A) content in the entire epoxy resin adhesive is preferably 20 to 90% by mass, preferably 30 to 80% by mass, particularly preferably 40 to 70% by mass, and even more preferably 45 to 60% by mass. This results in the adhesive having suitable hardness and cohesive force after curing, and thus having better laser cutting properties.

[0036] The epoxy resin (B) that yields a cured product with a Tg of 25°C or lower is an epoxy resin that yields a cured product with a Tg of 25°C or lower when cured alone or in the presence of a polymerization initiator. By using this epoxy resin (B), an active energy ray curable adhesive can be obtained that can be sufficiently cured by active energy ray irradiation alone, without the need for heat treatment. From this viewpoint, it is preferable that the epoxy resin (B) yields a cured product with a Tg of -5°C or lower, more preferably -20°C or lower, particularly preferably -40°C or lower, and even more preferably -60°C or lower. The lower limit of the above Tg is not particularly limited, but is usually -100°C or higher, and from the viewpoint of easily exhibiting the desired hardness, cohesive force, and tackiness, it is preferable to be -90°C or higher, and more preferably -80°C or higher. The Tg of the cured product of epoxy resin (B) can be measured using a differential scanning calorimetry analyzer in accordance with JIS K 7121.

[0037] The epoxy resin (B) is preferably liquid at 23°C. "Liquid at 23°C" means that it has fluidity at 23°C. By using an epoxy resin that is liquid at 23°C, an adhesive with excellent adhesion is obtained that develops tack at room temperature or mild high-temperature conditions.

[0038] The epoxy equivalent of epoxy resin (B) is preferably 100 to 500 g / eq, and particularly preferably 115 to 450 g / eq. This allows for the production of an adhesive layer with excellent bonding strength. The epoxy equivalent value can be measured in accordance with JIS K7236.

[0039] Examples of epoxy resin (B) include monofunctional epoxy resins and polyfunctional epoxy resins, with polyfunctional epoxy resins being preferred from the viewpoint of superior adhesive strength. Examples of polyfunctional epoxy resins include aliphatic epoxy compounds (excluding alicyclic epoxy compounds), aromatic epoxy compounds, and alicyclic epoxy compounds.

[0040] Examples of aliphatic epoxy compounds include 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol tetraglycidyl ether, dipentaerythritol hexaglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether.

[0041] Examples of aromatic epoxy compounds include glycidyl ethers and epoxy novolac resins of bisphenol A, bisphenol F, or compounds obtained by further adding alkylene oxides to these compounds; polyglycidyl ethers of aromatic compounds having two or more phenolic hydroxyl groups, such as resorcinol, hydroquinone, and catechol; glycidyl ethers of aromatic compounds having two or more alcoholic hydroxyl groups, such as phenyldimethanol, phenyldiethanol, and phenyldibutanol; and glycidyl esters of polybasic acid aromatic compounds having two or more carboxylic acids, such as phthalic acid, terephthalic acid, and trimellitic acid.

[0042] Examples of alicyclic epoxy compounds include polyglycidyl ethers of polyhydric alcohols having at least one alicyclic structure, such as dicyclopentadiene dimethanol diglycidyl ether and hydrogenated bisphenol A, as well as cycloalkene oxide compounds such as cyclohexene oxide and cyclopentene oxide-containing compounds obtained by epoxidizing cyclohexene or cyclopentene ring-containing compounds with an oxidizing agent.

[0043] As for epoxy resin (B), epoxy resins having an oxyalkylene structure are preferred from the viewpoint of tending to yield cured products with a relatively low Tg.

[0044] Examples of oxyalkylene structures include oxymethylene group, oxyethylene group, oxypropylene group, oxytrimethylene group, oxybutylene group, oxypentylene group, oxyhexylene group, oxyheptylene group, oxyoctylene group, oxynonylene group, oxydecylen group, oxyundecylen group, oxidedodecylen group, oxytridecylen group, oxytetradecylen group, oxypentadecylen group, oxycyclopropylene group, oxycyclobutylene group, oxycyclopentylene group, oxycyclohexylene group, oxydecahydronaphthalylene group, oxynorbornanylene group, and oxyadamantanylene group.

[0045] A commercially available epoxy resin having an oxyalkylene structure, which is liquid at 23°C, can also be used. For example, Mitsubishi Chemical Corporation's product name: YX7400 (cured product Tg: -69°C, epoxy equivalent: 440 g / eq) is one such example.

[0046] Furthermore, epoxy resin (B) can be used individually or in combination of two or more types.

[0047] The epoxy resin (B) content in the entire epoxy resin adhesive is preferably 20 to 90% by mass, preferably 30 to 80% by mass, particularly preferably 40 to 70% by mass, and even more preferably 45 to 60% by mass. This results in good adhesive properties for the resulting adhesive, and the adhesive after active energy ray curing has suitable hardness and cohesive force, leading to superior laser cutting processability.

[0048] The cationic polymerization initiator (C) can generate cationic species by irradiation with active energy rays and heating, thereby enabling the polymerization reaction of the epoxy resin (B) to proceed. It is preferable that the initiator generates cationic species by irradiation with active energy rays, and it is particularly preferable that the initiator generates cationic species by irradiation with ultraviolet light (photo-cationic polymerization initiator).

[0049] Photocationic polymerization initiators are preferred because they efficiently promote the polymerization reaction of epoxy resin (B) and improve the storage stability of the resulting adhesive layer 11 compared to other curing agents. A photocationic polymerization initiator consists of a cation portion that absorbs ultraviolet light and an anion portion that is a source of acid.

[0050] Examples of photocationic polymerization initiators include sulfonium salt compounds, iodonium salt compounds, phosphonium salt compounds, ammonium salt compounds, diazonium salt compounds, selenium salt compounds, oxonium salt compounds, and bromine salt compounds. Among these, sulfonium salt compounds are preferred due to their excellent compatibility with other components, and aromatic sulfonium salt compounds having aromatic groups are more preferred.

[0051] Examples of sulfonium salt compounds include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, 4,4'-bis[diphenylsulfonio]diphenylsulfide-bishexafluorophosphate, 4,4'-bis[di(β-hydroxyethoxy)phenylsulfonio]diphenylsulfide-bishexafluoroantimonate, 7-[di( [p-Toluyl)sulfonio]-2-isopropylthioxanthone hexafluorophosphate, 7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone hexafluoroantimonate, 7-[di(p-toluyl)sulfonio]-2-isopropyltetrakis(pentafluorophenyl)borate, phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide-hexafluorophosphate, phenylcarbonyl-4'-diphenylsulfonio-diphenyl Sulfide-hexafluoroantimonate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide-hexafluorophosphate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide-hexafluoroantimonate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide-tetrakis(pentafluorophenyl)borate, 4-(phenylthio)phenyldiphenylsulfonium hexafluoroantimonate, 4-(phenylthio)phenyldiphenylsulfonium hexafluorophosphate, 4-{4-(2-chlorobenzoyl)phenylthio}phenylbis(4-fluorophenyl)sulfonium hexafluoroantimonate, halogenated thiophenyldiphenylsulfonium hexafluoroantimonate, 4,4',4''-tri(β-hydroxyethoxyphenyl)sulfonium hexafluoroantimonate, 4,Examples include 4'-bis[diphenylsulfonio]diphenylsulfide-bishexafluoroantimonate, diphenyl[4-(phenylthio)phenyl]sulfonium trifluorotrispentafluoroethyl phosphate, tris[4-(4-acetylphenylsulfanyl)phenyl]sulfonium tris[(trifluoromethyl)sulfonyl]methanide, and salts in which the cation is 4-(phenylthio)phenyldiphenylsulfonium and the anion is a phosphorus-based anion with fluorine and a perfluoroalkyl group added.

[0052] Examples of iodonium salt compounds include diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di(4-nonylphenyl)iodonium hexafluorophosphate, and (tricumyl)iodonium tetrakis(pentafluorophenyl)borate.

[0053] Examples of phosphonium salt compounds include tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributylphosphonium chloride.

[0054] Examples of ammonium salt compounds include benzyltrimethylammonium chloride, phenyltributylammonium chloride, and benzyltrimethylammonium bromide.

[0055] Furthermore, cationic polymerization initiators (C) can be used individually or in combination of two or more types.

[0056] The content of cationic polymerization initiator (C) in the entire epoxy resin adhesive is preferably 0.1 to 5% by mass, particularly preferably 0.5 to 4% by mass, and even more preferably 1 to 3% by mass. This results in the adhesive having suitable hardness and cohesive force after active energy ray curing, and thus having better laser cutting properties.

[0057] Various additives, such as silane coupling agents, fillers, colorants, UV absorbers, infrared absorbers, refractive index modifiers, antistatic agents, tackifiers, rust inhibitors, antioxidants, light stabilizers, softeners, and oxygen absorbers, can be added to epoxy resin adhesives.

[0058] Epoxy resin adhesives can be manufactured by conventional methods. When applying epoxy resin adhesives, a diluting solvent can be added as desired to obtain a coating solution diluted with the solvent.

[0059] Examples of the diluent solvents used include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

[0060] The concentration and viscosity of the coating solution are not particularly limited, as long as they are within the range that allows for coating, and can be appropriately selected depending on the situation.

[0061] (2) Polyester adhesive Preferably, the polyester adhesive is obtained by crosslinking an adhesive composition containing a polyester polymer (D) having reactive functional groups and a crosslinking agent (E). In particular, it is preferred that the adhesive composition containing a polyester polymer (D) having reactive functional groups, a crosslinking agent (E), and an active energy ray curable component (F) is crosslinked and cured with active energy rays. This adhesive has hardness and cohesive strength suitable for laser cutting, resulting in superior laser cutting performance. From the perspective of SDGs, materials with a high biomass content may be used as the constituent material of the polyester adhesive, materials that can be recycled or reused may be used, or recycled or reused materials may be used.

[0062] The polyester polymer (D) having reactive functional groups may be composed of a saturated polyester resin or an unsaturated polyester resin. In this embodiment, the polyester polymer (D) is preferably a saturated polyester resin. A saturated polyester resin can be obtained, for example, by condensation polymerization of a polycarboxylic acid and a polyol.

[0063] Polycarboxylic acids are compounds that have multiple carboxyl groups. Examples of polycarboxylic acids include aromatic polycarboxylic acids, alicyclic dicarboxylic acids, aliphatic polycarboxylic acids, and their ester-forming derivatives. These may be used individually or in combination of two or more types.

[0064] Polyols are compounds that have multiple hydroxyl groups. Examples of polyols include aliphatic polyols, aromatic polyols, and their ester-forming derivatives. These may be used individually or in combination of two or more types.

[0065] The responsive functional groups of the polyester polymer (D) react with the crosslinking agent (E), and through this reaction with the crosslinking agent (E) via the responsive functional groups, a crosslinked structure as a three-dimensional network structure is formed in the adhesive. As a result, the adhesive has suitable hardness and cohesive force, and its laser cutting processability is improved.

[0066] Examples of reactive functional groups that the polyester polymer (D) may possess include hydroxyl groups, carboxyl groups, and amino groups, with hydroxyl groups being preferred as they have less adverse effect on the adherend. The polyester polymer (D) may have one of these reactive functional groups or two or more.

[0067] The Tg of the polyester polymer (D) is preferably -100°C to 20°C, more preferably -60°C to 15°C, particularly preferably -20°C to 10°C, and even more preferably -5°C to 5°C. This results in superior laser cutting properties.

[0068] The weight-average molecular weight of the polyester polymer (D) is preferably 20,000 to 2,000,000, more preferably 50,000 to 1,400,000, particularly preferably 80,000 to 800,000, even more preferably 100,000 to 400,000, and most preferably 120,000 to 200,000. This results in superior laser-cutting properties. The weight-average molecular weights used herein are values ​​on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0069] In polyester-based adhesives, the polyester polymer (D) may be used alone or in combination of two or more types.

[0070] Commercially available products can also be used as the polyester polymer (D). Examples of commercially available products include Nichigo Polyester® NP-110S50EO, Nichigo Polyester® S-0091S55EO, and Nichigo Polyester® S-0097S55EO, all manufactured by Mitsubishi Chemical Corporation. Among these, Nichigo Polyester® S-0097S55EO is preferred.

[0071] The polyester polymer (D) content in the total polyester adhesive is preferably 50 to 99.9% by mass, more preferably 60 to 99% by mass, particularly preferably 65 to 95% by mass, and even more preferably 70 to 90% by mass. This results in superior laser cutting properties.

[0072] The crosslinking agent (E) can be any agent capable of reacting with the reactive functional groups of the polyester polymer (D) to form a crosslinked structure. Examples of crosslinking agents (E) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. The crosslinking agent (E) can be used alone or in combination of two or more types.

[0073] When the reactive group of the polyester polymer (D) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that has high reactivity with the hydroxyl group.

[0074] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret and isocyanurate forms, as well as adducts which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

[0075] The crosslinking agent (E) content in the polyester adhesive is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 8 parts by mass, particularly preferably 0.4 to 6 parts by mass, even more preferably 0.8 to 4 parts by mass, and most preferably 1.2 to 3 parts by mass, per 100 parts by mass of polyester polymer (D). This results in the crosslinked adhesive having suitable hardness and cohesive force, and thus having better laser cutting processability.

[0076] In this embodiment, when the polyester adhesive contains an active energy ray curable component (F), it is presumed that in the adhesive obtained by thermal crosslinking and active energy ray curing of the polyester adhesive, the active energy ray curable components (F) polymerize with each other, and the polymerized active energy ray curable components (F) become entangled in the crosslinked structure (three-dimensional network structure) of the polyester polymer (D). An adhesive having such a higher-order structure will have more suitable hardness and cohesive force, and will have excellent laser-cutting processability.

[0077] The active energy ray curable component (F) is not particularly limited as long as it is a component that hardens upon irradiation with active energy rays and produces the above-mentioned effects, and may be a monomer, oligomer, or polymer, or a mixture thereof. Among these, polyfunctional acrylate monomers that exhibit superior adhesive strength after hardening are particularly preferred.

[0078] Examples of polyfunctional acrylate monomers include bifunctional types such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, di(acryloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; trimethyl Examples include trifunctional types such as rolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate; tetrafunctional types such as diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; pentafunctional types such as propionic acid-modified dipentaerythritol penta(meth)acrylate; and hexafunctional types such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. Among the above, from the viewpoint of improving hardness after active energy ray curing, ethylene oxide-modified isocyanuric acid di(meth)acrylate, ethylene oxide-modified isocyanuric acid tri(meth)acrylate, or mixtures thereof are preferred. These may be used individually or in combination of two or more. Furthermore, from the viewpoint of compatibility with other compounding materials such as polyester polymers (D), polyfunctional acrylate monomers with a molecular weight of less than 5000 are preferred, those with a molecular weight of less than 3000 are more preferred, and those with a molecular weight of less than 1000 are particularly preferred.

[0079] When the polyester adhesive contains an active energy ray curable component (F), the content is preferably 1 to 50 parts by mass, more preferably 4 to 45 parts by mass, particularly preferably 8 to 40 parts by mass, even more preferably 12 to 36 parts by mass, and most preferably 16 to 32 parts by mass, per 100 parts by mass of the polyester polymer (D). This results in the adhesive having more suitable hardness and cohesive force after active energy ray curing, and exhibiting excellent laser cutting processability.

[0080] In this embodiment, when the polyester adhesive contains an active energy ray-curable component (F) and ultraviolet light is used as the active energy ray, it is preferable to include a photopolymerization initiator (G). This allows the active energy ray-curable component (F) to cure efficiently, resulting in superior laser cutting properties. Furthermore, the polymerization curing time and the amount of ultraviolet light irradiation can be reduced.

[0081] Examples of photopolymerization initiators (G) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4, Examples include 4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide. These may be used individually or in combination of two or more.

[0082] When the polyester adhesive contains a photopolymerization initiator (G), the amount is preferably 0.01 to 10 parts by mass, more preferably 0.04 to 5 parts by mass, particularly preferably 0.08 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the active energy ray curable component (F). This results in improved laser cutting properties.

[0083] In this embodiment, the polyester adhesive preferably further contains a catalyst (H). This promotes crosslinking during the formation of the crosslinked structure of the polyester adhesive, thereby shortening the curing period of the adhesive. Furthermore, a suitable crosslinking rate makes it easier for the resulting polyester adhesive to have a suitable crosslinked structure that exhibits the desired properties.

[0084] Examples of catalysts (H) include metal chelate compounds containing metal atoms such as aluminum, zirconium, titanium, zinc, iron, and tin. From a performance viewpoint, zirconium chelate compounds or aluminum chelate compounds are preferred, and zirconium chelate compounds are particularly preferred. Furthermore, these metal chelate compounds are preferably acetylacetone complexes.

[0085] Examples of zirconium chelate compounds include zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium monobutoxyacetylacetonate bis(ethyl acetoacetate), and zirconium dibutoxybis(ethyl acetoacetate), with zirconium tetraacetylacetonate being preferred. These may be used individually or in combination of two or more.

[0086] Examples of aluminum chelating compounds include diisopropoxyaluminum monooleyl acetate, monoisopropoxyaluminum bisoleyl acetate, monoisopropoxyaluminum monooleate monoethyl acetate, diisopropoxyaluminum monolauryl acetate, diisopropoxyaluminum monostearyl acetate, diisopropoxyaluminum monoisostearyl acetate, monoisopropoxyaluminum mono-N-lauroyl-β-aranate monolauryl acetate, aluminum trisacetylacetonate, monoacetylacetonate aluminum bis(isobutyl acetate) chelate, monoacetylacetonate aluminum bis(2-ethylhexyl acetate) chelate, monoacetylacetonate aluminum bis(dodecyl acetate) chelate, and monoacetylacetonate aluminum bis(oleyl acetate) chelate, with aluminum trisacetylacetonate being preferred. These can be used individually or in combination of two or more types.

[0087] When the polyester adhesive contains a catalyst (H), the amount is preferably 0.001 to 0.1 parts by mass, more preferably 0.005 to 0.08 parts by mass, particularly preferably 0.01 to 0.06 parts by mass, and even more preferably 0.02 to 0.04 parts by mass, per 100 parts by mass of the polyester polymer (D). This results in improved laser cutting properties.

[0088] Polyester adhesives can contain various additives, such as silane coupling agents, fillers, colorants, UV absorbers, infrared absorbers, refractive index modifiers, antistatic agents, tackifiers, rust inhibitors, antioxidants, light stabilizers, softeners, and oxygen absorbers.

[0089] Among the polyester-based adhesives, it is preferable that they contain a silane coupling agent (I). This improves adhesion to the adherend, making it easier for the resulting adhesive to achieve the desired adhesive strength.

[0090] The silane coupling agent (I) is preferably an organosilicon compound having at least one alkoxysilyl group in its molecule, which has good compatibility with the polyester polymer (D) and is light-transmitting.

[0091] Examples of silane coupling agents (I) include polymerizable unsaturated silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Examples include silicon compounds containing a capto group, amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, or condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used individually or in combination of two or more.

[0092] The content of the silane coupling agent (I) in the polyester adhesive is preferably 0.01 to 1 part by mass, more preferably 0.1 to 0.7 parts by mass, and particularly preferably 0.2 to 0.5 parts by mass, per 100 parts by mass of polyester polymer (D). This provides good adhesion to the adherend.

[0093] Polyester adhesives can be manufactured by conventional methods. When applying polyester adhesives, a diluent solvent can be added as desired to obtain a diluted coating solution. The same solvents as those mentioned above can be used as diluent solvents.

[0094] (3) Thickness of the adhesive layer The thickness of the adhesive layer 11 (measured according to JIS K7130) is preferably 1 to 500 μm, more preferably 5 to 250 μm, more preferably 10 to 150 μm, particularly preferably 20 to 100 μm, even more preferably 30 to 60 μm, and most preferably 40 to 55 μm. This allows for better laser cutting processability while maintaining the desired adhesive strength.

[0095] 1-2. Release sheet Examples of release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester polymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Crosslinked films of these materials can also be used. Furthermore, laminated films of these materials may also be used. From an SDG perspective, materials with a high biomass content may be used as the material constituting the release sheet, materials that can be recycled or reused may be used, or recycled or reused materials may be used.

[0096] It is preferable that the release surfaces of the release sheets 12a and 12b (especially the surfaces in contact with the adhesive layer 11) are subjected to a release treatment. Examples of release agents used in the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax-based release agents.

[0097] There are no particular restrictions on the thickness of the release sheets 12a and 12b, but they are usually preferably 10 to 250 μm, and particularly preferably 20 to 150 μm.

[0098] In the two release sheets 12a and 12b described above, it is preferable that one release sheet be a heavy-peel type release sheet with a high peeling force, and the other release sheet be a light-peel type release sheet with a low peeling force.

[0099] 2. Manufacturing method One example of manufacturing the adhesive sheet 1 involves applying the adhesive coating solution constituting the adhesive layer 11 to the release surface of one release sheet 12a (or 12b), and performing a heat treatment as necessary to form the adhesive layer 11. The release surface of the other release sheet 12b (or 12a) is then placed on top of the adhesive layer 11. In the case of the polyester-based adhesive described above, the crosslinking reaction can be advanced by heat treatment. This heat treatment can also be combined with the drying treatment used to volatilize the dilution solvent, etc., from the adhesive coating layer applied to the desired object.

[0100] The heating temperature for the heat treatment is preferably 50 to 150°C, and more preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes.

[0101] In the polyester-based adhesive described above, it is preferable to irradiate the adhesive layer with active energy rays at the stage of the adhesive sheet 1 before it is attached to the substrate, thereby curing the polyester-based adhesive with active energy rays. This results in improved laser cutting properties.

[0102] Active energy rays refer to electromagnetic waves or charged particle beams that possess energy quanta, and specifically include ultraviolet rays and electron beams, with ultraviolet rays being particularly preferred due to their ease of handling.

[0103] Ultraviolet irradiation can be performed using high-pressure mercury lamps, Heraeus H lamps, xenon lamps, etc., with an illuminance of 50-1000 mW / cm². 2 Preferably, this is the case, and especially 100-600 mW / cm². 2 It is preferable that the light intensity be 50 to 10,000 mJ / cm². 2 Preferably, the concentration is 100-5000 mJ / cm². 2 It is more preferable that the concentration be 300-2000 mJ / cm². 2 It is particularly preferable that this is the case. On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose is preferably about 10 to 1000 krad.

[0104] 3. Physical properties (1) Creep distortion For the adhesive layer 11 of the adhesive sheet 1 (or the adhesive layer after active energy ray curing in the case of an active energy ray curable adhesive layer), the strain (creep strain) when a pressure of 10 kPa is applied for 600 seconds at a temperature of 23°C and a frequency of 1 Hz using the torsional shear method in accordance with JIS K7244-6 is preferably 100% or less, more preferably 75% or less, particularly preferably 50% or less, even more preferably 25% or less, most preferably 10% or less, and especially preferably 5% or less. This results in the adhesive layer 11 having a hardness more suitable for laser cutting, and thus having excellent laser cutting properties. Considering the adhesiveness, the lower limit of the above creep strain is preferably 0.1% or more, more preferably 0.4% or more, particularly preferably 0.8% or more, and even more preferably 1% or more. Details of the creep strain measurement method in this specification are shown in the test examples described later.

[0105] (2) Gel fraction The gel fraction of the adhesive constituting the adhesive layer 11 is preferably 20-99%, more preferably 30-90%, particularly preferably 35-85%, even more preferably 40-80%, and among these, preferably 44-76%, and especially preferably 48-72%. This results in the adhesive layer 11 having cohesive force more suitable for laser cutting, and thus exhibiting excellent laser cutting properties. It also exhibits suitable adhesive properties. The method for measuring the gel fraction in this specification is as shown in the test examples described later.

[0106] When the adhesive constituting the adhesive layer 11 is curable by active energy rays, the gel fraction after curing by active energy rays is preferably 30-99%, more preferably 45-98%, particularly preferably 60-97%, even more preferably 75-96%, and most preferably 85-95%. This results in the adhesive layer 11 having cohesive force more suitable for laser cutting, and thus exhibiting excellent laser cutting properties. It also exhibits suitable adhesive properties.

[0107] (3) Adhesive strength The adhesive strength of the adhesive sheet 1 according to this embodiment to soda-lime glass is preferably 0.1 N / 25 mm or more, more preferably 0.3 N / 25 mm or more, particularly preferably 0.6 N / 25 mm or more, and even more preferably 0.8 N / 25 mm or more. This makes it less likely for lifting or peeling to occur at the interface between the adhesive layer 11 and the adherend (e.g., light-emitting substrate / surface substrate) during laser cutting, resulting in excellent adhesion.

[0108] Furthermore, the adhesive strength is preferably 10 N / 25 mm or less, more preferably 7 N / 25 mm or less, particularly preferably 4 N / 25 mm or less, and even more preferably 2 N / 25 mm or less. This ensures good reworkability, and allows for the reuse of the adherend if an adhesion error occurs.

[0109] Herein, the adhesive strength referred to in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2022. The measurement sample shall be 25 mm wide and 100 mm long, and the measurement sample shall be attached to the substrate, pressurized at 0.5 MPa and 50°C for 20 minutes, then left for 24 hours under normal pressure, 23°C, and 50% relative humidity conditions, and measured at a peeling speed of 300 mm / min. In this specification, "relative humidity α%" may be expressed as "α%RH" (RH; Relative humidity).

[0110] (4) Adhesion after curing with active energy rays When the adhesive is curable by active energy rays, the adhesive strength of the adhesive sheet 1 to the soda-lime glass (adhesive strength after active energy ray curing) after the adhesive layer 11 of the adhesive sheet 1 is attached to the soda-lime glass and the adhesive layer 11 is cured by active energy rays is preferably 0.2 N / 25 mm or more, more preferably 1 N / 25 mm or more, particularly preferably 10 N / 25 mm or more, even more preferably 25 N / 25 mm or more, and most preferably 35 N / 25 mm or more, and especially preferably 45 N / 25 mm or more. This makes it less likely for lifting or peeling to occur at the interface between the active energy ray cured adhesive layer 11 and the adherend (e.g., light-emitting substrate / surface substrate) during laser cutting, resulting in excellent adhesion.

[0111] Furthermore, the adhesive strength is preferably 100 N / 25 mm or less, more preferably 75 N / 25 mm or less, and particularly preferably 60 N / 25 mm or less. This ensures good reworkability, and allows for the reuse of the adherend if an adhesion error occurs.

[0112] (5) Elongation at break The elongation at break of the adhesive layer 11 of the adhesive sheet 1 (or the adhesive layer after active energy ray curing in the case of an active energy ray curable adhesive layer) measured by a tensile test performed at a tensile speed of 200 mm / min is preferably 1000% or less, more preferably 600% or less, particularly preferably 300% or less, even more preferably 200% or less, and most preferably 150% or less. This gives the adhesive layer 11 a hardness more suitable for laser cutting, resulting in excellent laser cutting properties. The lower limit of the above elongation at break is preferably 1% or more, more preferably 20% or more, particularly preferably 40% or more, even more preferably 60% or more, most preferably 70% or more, and especially preferably 74% or more, from the viewpoint of adhesiveness. The tensile test shall be performed with a measurement width of 10 mm and a measurement length of 25 mm, in an environment of 23°C and 50% RH. Detailed test procedures are as shown in the test examples described later.

[0113] The above-mentioned elongation at break is preferably satisfied both in the line direction (MD) during the manufacturing of the adhesive layer 11 and in the direction perpendicular to the MD (TD). However, the value of elongation at break tends to be larger in the MD than in the TD. The ratio of MD to TD (MD / TD) is preferably 0.5 to 5, more preferably 0.7 to 3, particularly preferably 0.9 to 2, and even more preferably 1 to 1.7. This makes it possible to suppress the leakage of adhesive at each edge during laser cutting when the unit panel is, for example, rectangular.

[0114] (6) Fracture stress The breaking stress measured by performing a tensile test on the adhesive layer 11 of the adhesive sheet 1 (or the adhesive layer after active energy ray curing in the case of an active energy ray curable adhesive layer) by stretching it at a tensile speed of 200 mm / min is preferably 10 MPa or more, more preferably 40 MPa or more, particularly preferably 80 MPa or more, even more preferably 100 MPa or more, and most preferably 120 MPa or more. This gives the adhesive layer 11 a hardness that is more suitable for laser cutting, resulting in excellent laser cutting properties. The upper limit of the breaking stress is preferably 1000 MPa or less, more preferably 750 MPa or less, particularly preferably 500 MPa or less, even more preferably 300 MPa or less, and most preferably 240 MPa or less, from the viewpoint of adhesiveness. The tensile test shall be performed with a measurement width of 10 mm and a measurement length of 25 mm, in an environment of 23°C and 50% RH. Detailed test procedures are as shown in the test examples described later.

[0115] The above-mentioned fracture stress is preferably satisfied both in the line direction (MD) during the manufacturing of the adhesive layer 11 and in the direction perpendicular to the MD (TD). However, the fracture stress value is usually smaller in the MD than in the TD. The ratio of MD to TD (MD / TD) is preferably 0.1 to 5, more preferably 0.3 to 2, particularly preferably 0.5 to 1.5, and even more preferably 0.6 to 1. This makes it possible to suppress the leakage of adhesive at each edge during laser cutting when the unit panel is, for example, rectangular.

[0116] (7) Total light transmittance The total light transmittance of the adhesive layer 11 of the adhesive sheet 1 is preferably 10% or more, preferably 40% or more, particularly preferably 80% or more, and even more preferably 90% or more. This ensures good visibility as a tiling display. On the other hand, the upper limit of the total light transmittance is not particularly limited, but is usually 100% or less. If the adhesive layer 11 is curable by active energy rays, it is preferable that the total light transmittance is within the same range as above both before and after curing by active energy rays. Here, the total light transmittance in this specification is the value measured in accordance with JIS K7361-1:1997.

[0117] (8) Haze value The haze value of the adhesive layer 11 of the adhesive sheet 1 is preferably 90% or less, more preferably 60% or less, particularly preferably 30% or less, even more preferably 10% or less, and most preferably 2% or less, and especially preferably 1% or less. This ensures good visibility as a tiling display. On the other hand, the lower limit of the above haze value is not particularly limited, but is usually 0% or more. If the adhesive layer 11 is curable by active energy rays, it is preferable that the haze value is within the same range as above both before and after active energy ray curing. The haze value in this specification is the value measured in accordance with JIS K7136:2000.

[0118] (9) Dimensional change rate The dimensional change rate (negative value for shrinkage, positive value for expansion) of the adhesive layer 11 of the adhesive sheet 1 (or the adhesive layer after active energy ray curing in the case of an active energy ray curable adhesive layer) due to heating of the MD and TD is preferably 0% or more as a lower limit. The upper limit of this dimensional change rate is preferably 10% or less, more preferably 7% or less, particularly preferably 4% or less, even more preferably 2% or less, most preferably 1.5% or less, and especially preferably 1% or less. This ensures that the adhesive layer 11 maintains a predetermined shape. As a result, even when the edges of a unit panel having the adhesive layer 11 are laser-cut to form a flat edge, the leakage of adhesive from the edge is more effectively suppressed. The method for measuring the above dimensional change rate is as shown in the test examples described later.

[0119] [Unit Panel] The unit panel according to an embodiment of the present invention constitutes a tiling display. An example of a unit panel according to one embodiment of the present invention is shown in Figure 2.

[0120] As shown in Figure 2, a unit panel 2 according to one embodiment of the present invention comprises a light-emitting substrate 21, a surface substrate 22, and an adhesive layer 11 positioned between them to bond the light-emitting substrate 21 and the surface substrate 22. The adhesive layer 11 is obtained from the adhesive layer 11 of the adhesive sheet 1 according to the above embodiment.

[0121] Furthermore, if the adhesive layer 11 of the adhesive sheet 1 is composed of an active energy ray-curable adhesive, the adhesive layer 11 in the unit panel 2 is in the state after active energy ray curing.

[0122] The shape of unit panel 2 in plan view is usually rectangular, but is not limited to this, and may be any desired polygon.

[0123] In this embodiment, the light-emitting substrate 21 is a substrate (module) equipped with a light-emitting element for displaying an image. Examples of types of light-emitting elements include light-emitting diodes (LEDs), laser diodes (LDs), organic electroluminescent light-emitting elements, and inorganic electroluminescent light-emitting elements. Among these, LEDs are preferred, and mini-LEDs or micro-LEDs are particularly preferred.

[0124] The light-emitting substrate 21 may also include desired optical components in addition to the light-emitting element. Examples of such optical components include light-diffusing members, brightness-enhancing films, contrast-enhancing films, viewing angle compensation films, transparent conductive films, liquid crystal polymer films, semi-transparent reflective films, and shatterproof films.

[0125] The surface substrate 22 is preferably a protective panel made of a glass plate, a plastic plate, or a laminate containing these. The glass plate is not particularly limited and includes, for example, chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium-borosilicate glass, etc. The plastic plate is not particularly limited and includes, for example, an acrylic plate, a polycarbonate plate, etc.

[0126] Furthermore, various functional layers (such as transparent conductive films, metal layers, silica layers, hard coat layers, and anti-glare layers) may be provided on one or both sides of the glass or plastic plate, or optical components as described above may be laminated on them. In addition, the transparent conductive film and metal layer may be patterned.

[0127] To manufacture the unit panel 2, as an example, one release sheet 12b of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to one side of the surface substrate 22. Then, the other release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the light-emitting substrate 21. Alternatively, as another example, the bonding order of the surface substrate 22 and the light-emitting substrate 21 may be reversed.

[0128] In this case, if the adhesive layer 11 of the adhesive sheet 1 is curable by active energy rays, it is preferable to cure the adhesive layer 11 by irradiating it with active energy rays from one side (preferably the side of the surface substrate 22) after laminating the surface substrate 22, the adhesive layer 11, and the light-emitting substrate 21. As a result, the adhesive layer 11 will have hardness and cohesive force that is more suitable for laser cutting, and will have excellent laser cutting properties.

[0129] The type of active energy ray and irradiation conditions are the same as when irradiating the adhesive layer of the adhesive sheet 1 before application to the substrate with active energy rays, as described above for polyester-based adhesives.

[0130] As described above, after creating a laminate as a unit panel 2, it is preferable to laser-cut the end face of the laminate to form a flat end face to create a unit panel 2. In the unit panel 2 obtained in this way, since the adhesive layer 11 described above is used, the leakage of adhesive from the laser-cut end face is suppressed. As a result, in a tiling display made by joining multiple unit panels 2, there are almost no gaps between the unit panels, thereby obtaining uniform brightness and high image quality.

[0131] The irradiation of laser light in laser cutting can be carried out under general conditions. The laser to be used is not particularly limited. For example, gas lasers such as carbon dioxide (CO2) lasers, TEA-CO2 lasers, excimer lasers, liquid lasers such as organic chelate compound lasers, inorganic lasers, organic dye lasers, solid lasers such as YAG lasers, UV-YAG lasers, YVO4 lasers, YLF lasers, semiconductor lasers such as vertical cavity surface emitting lasers, quantum dot lasers, etc. can be utilized. Among these, from the viewpoint of obtaining a large laser output and excellent workability, gas lasers are preferred, and among them, carbon dioxide (CO2) lasers or TEA-CO2 lasers are preferred.

[0132] The wavelength of the laser light to be irradiated is preferably 0.1 to 1000 μm, more preferably 0.38 to 100 μm, particularly preferably 0.78 to 50 μm, still more preferably 1 to 25 μm, and among them, preferably 8 to 20 μm. Also, the power density of the laser is generally 1.0×10 3 ~1.0×10 10 W / cm 2 and preferably 1.0×10 4 ~1.0×10 8 W / cm 2 The irradiation time of the laser is generally 1.0×10 -8 ~1 second, and preferably 1.0×10 -5 ~1.0×10 -1 seconds.

[0133] 〔Tiling Display〕 The tiling display according to an embodiment of the present invention is formed by connecting a plurality of unit panels 2 according to the above-described embodiment. The connection method can be carried out by a conventional method.

[0134] By joining together multiple unit panels 2, each with laser-cut edges that suppress adhesive seepage, the gaps between the unit panels 2 are virtually eliminated. As a result, the tiling display according to this embodiment achieves uniform brightness and high image quality.

[0135] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0136] For example, either the release liner 12a or 12b in the adhesive sheet 1 may be omitted. Also, the unit panel 2 may include other desired layers.

[0137] In this specification, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "less than or equal to Y" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y." [Examples]

[0138] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0139] [Example 1] A coating solution for an epoxy resin-based adhesive was obtained by mixing 50 parts by mass (solid content equivalent; the same applies hereinafter) of phenoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YX7200B35", Tg: 150℃, Mw: 30,000) as epoxy resin (A) with a Tg of 50℃ or higher, 50 parts by mass of epoxy resin (B) having oxyalkylene groups (liquid at 23℃) (manufactured by Mitsubishi Chemical Corporation, product name "YX7400", epoxy equivalent: 440 g / eq, Tg of cured product: -69℃) as epoxy resin (B) that gives a cured product with a Tg of 25℃ or lower, and 2.0 parts by mass of 4-(phenylthio)phenyldiphenylsulfonium hexafluorophosphate (photocationic polymerization initiator) as a cationic polymerization initiator (C), stirring thoroughly, and diluting with methyl ethyl ketone.

[0140] Table 1 shows the respective formulations (solid content equivalent) of the adhesive when the total amount of the main adhesive component is 100 parts by mass (solid content equivalent).

[0141] The epoxy resin adhesive coating solution described above was applied to the release-treated surface of a heavy-peel type release sheet R1, which was obtained by releasing one side of a polyethylene terephthalate film with a silicone-based release agent, using a knife coater. The sheet was then heated at 100°C for 2 minutes to form an active-energy ray-curable adhesive layer (thickness: 50 μm). The release-treated surface of a light-peel type release sheet R2, which was obtained by releasing one side of a polyethylene terephthalate film with a silicone-based release agent, was laminated to this adhesive layer to obtain an adhesive sheet having a layer structure of release sheet R2 / adhesive layer (50 μm) / release sheet R1.

[0142] The thickness of each layer described above was measured in accordance with JIS K7130 using a constant-pressure thickness measuring instrument (TECLOCK Co., Ltd., product name "PG-02") (the same applies hereafter). Furthermore, regarding the peeling force of release sheet R1 and release sheet R2 in the obtained adhesive sheet, it was confirmed that release sheet R1 has a greater peeling force than release sheet R2.

[0143] [Example 2] The mixture comprises 100 parts by mass of a polyester polymer (manufactured by Mitsubishi Chemical Corporation, product name "Nichigo Polyester S-0097S55EO", high molecular weight saturated copolymer polyester resin, Tg: 1℃, weight-average molecular weight (Mw): 130,000) as a polyester polymer having reactive functional groups (D), 2.5 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (E), and a mixture of ethylene oxide-modified isocyanuric acid diacrylate and ethylene oxide-modified isocyanuric acid tri(meth)acrylate (manufactured by Toagosei Co., Ltd., product name "Aronics") as an active energy ray curable component (F). A polyester adhesive coating solution was obtained by mixing 30 parts by mass of "M-315", 0.3 parts by mass of a mixture of 1-hydroxycyclohexylphenyl ketone and benzophenone in a 1:1 mass ratio as a photopolymerization initiator (G), 0.02 parts by mass of zirconium tetraacetylacetonate as a catalyst (H), and 0.25 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (I), stirring thoroughly, and diluting with methyl ethyl ketone. The weight-average molecular weight (Mw) of the above polyester polymer was measured by the method described later.

[0144] The above polyester adhesive coating solution was applied using a knife coater to the release-treated surface of a heavy-peel type release sheet R1, which had one side of a polyethylene terephthalate film released with a silicone-based release agent. The sheet was then heated at 90°C for 1 minute to promote the cross-linking reaction and form a coating layer (thickness: 50 μm). The release-treated surface of a light-peel type release sheet R2, which had one side of a polyethylene terephthalate film released with a silicone-based release agent, was then laminated to this coating layer. The coating layer was cured by irradiating it with active energy rays (ultraviolet light; UV) through the release sheet R1, forming an adhesive layer. The active energy ray irradiation conditions were as follows:

[0145] <Activated energy ray irradiation conditions> • Use of high-pressure mercury lamps ·Illuminance 200mW / cm 2 , light intensity 1000mJ / cm 2 • The UV irradiance / light intensity meter used is the "UVPF-A1" manufactured by iGraphics Co., Ltd.

[0146] Subsequently, by curing for 7 days under conditions of 23°C and 50%RH, an adhesive sheet having a layer structure of release sheet R2 / adhesive layer (50 μm) / release sheet R1 was obtained.

[0147] [Comparative Example 1] 1. Preparation of (meth)acrylic acid ester polymers A (meth)acrylic acid ester polymer was prepared by copolymerizing 27.5 parts by mass of n-butyl acrylate, 27.5 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobonyl acrylate, 5 parts by mass of N-acryloylmorpholine, and 25 parts by mass of 2-hydroxyethyl acrylate by solution polymerization. The molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, and the weight-average molecular weight (Mw) was found to be 500,000.

[0148] 2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above process, 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (E), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (I) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (CE1).

[0149] 3. Manufacturing of adhesive sheets The coating solution of the adhesive composition (CE1) obtained in the above process was applied with a knife coater to the peeled surface of a double-peel type release sheet R1, which was obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent. The coating was then heated at 90°C for 1 minute to form a coating layer (thickness: 100 μm), which was used as the first laminate.

[0150] Similarly, the coating solution of the above-mentioned adhesive composition (CE1) was applied with a knife coater to the release-treated surface of a light-peel type release sheet R2, which was obtained by releasing one side of a polyethylene terephthalate film with a silicone-based release agent. The coating was then heated at 90°C for 1 minute to form a coating layer (thickness: 100 μm), which was used as the second laminate.

[0151] Subsequently, the coating layer of the first laminate and the coating layer of the second laminate were bonded together and cured for 7 days under conditions of 23°C and 50%RH to obtain an adhesive sheet having a layer structure of release sheet R2 / adhesive layer (200 μm) / release sheet R1.

[0152] The weight-average molecular weight (Mw) mentioned above is the weight-average molecular weight in polystyrene terms, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> • GPC measuring device: Tosoh Corporation, HLC-8020 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Guard Column HXL-H TSK gel GMHXL (x2) TSK gel G2000HXL • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0153] [Test Example 1] (Measurement of gel fraction) The adhesive sheets produced in the examples and comparative examples were cut to a size of 80 mm x 80 mm, and the adhesive layer was wrapped in a polyester mesh (mesh size 200). The mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass was denoted as M1.

[0154] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Afterward, the adhesive was removed and air-dried for 24 hours at 23°C and 50% RH, followed by 12 hours of drying in an oven at 80°C. After drying, its mass was measured using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass is denoted as M2. The gel fraction (%) is expressed as (M2 / M1) × 100. The results are shown in Table 2.

[0155] Furthermore, for the adhesive sheet in Example 1, the gel fraction (after UV irradiation) was also measured after irradiating the adhesive layer with active energy rays (ultraviolet light; UV) through the release sheet R2. The irradiation conditions for the active energy rays were the same as those used to cure the adhesive layer in Example 2.

[0156] [Test Example 2] (Measurement of creep strain) A cylindrical object with a diameter of 8 mm was punched out from the adhesive layer of the adhesive sheets in the examples and comparative examples, and this was used as a sample. For the adhesive sheet in Example 1, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0157] For the above samples, the strain (creep strain) (%) was measured using the torsional shear method with a viscoelasticity measuring device (Anton Paar, product name "MCR302") in accordance with JIS K7244-6, when a pressure of 10 kPa was applied for 600 seconds under the following conditions. The results are shown in Table 2. Measurement frequency: 1Hz Measurement temperature: 23℃

[0158] [Test Example 3] (Tensile Test) Samples measuring 10 mm wide x 75 mm long (MD / TD) were cut from the adhesive layer of the adhesive sheets in the examples and comparative examples. For the adhesive sheet in Example 1, the adhesive layer was cured using active energy rays in the same manner as in Test Example 1.

[0159] The sample was placed in a tensile testing machine (Orientec Co., Ltd., product name "Tensilon") so that the measurement area of ​​the sample was 10 mm wide x 25 mm long (in the elongation direction), and the sample was stretched at a tensile speed of 200 mm / min using the tensile testing machine in an environment of 23°C and 50% RH. The sample was stretched until it broke, and the elongation at break (%) and breaking stress (MPa) were measured. This measurement was performed for both MD and TD. The results are shown in Table 2.

[0160] Furthermore, the ratio of the elongation at break of MD to the elongation at break of TD (MD / TD) and the ratio of the fracture stress of MD to the fracture stress of TD (MD / TD) were calculated. The results are shown in Table 2.

[0161] [Test Example 4] (Measurement of Adhesion) The release sheet R2 was peeled off from the adhesive sheets produced in the examples and comparative examples, and the exposed adhesive layer was laminated to the easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine PET A4360", thickness: 100 μm) having an easy-adhesion layer, thereby obtaining a laminate of release sheet R1 / adhesive layer / PET film. The obtained laminate was cut to a width of 25 mm and a length of 100 mm.

[0162] Under conditions of 23°C and 50%RH, the release sheet R1 was peeled from the laminate, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The sample was then subjected to 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. After that, it was left for 24 hours under conditions of 23°C and 50%RH, and this was used as a sample. The adhesive strength (before UV; N / 25mm) was then measured using a tensile testing machine (manufactured by Orientec Co., Ltd., product name "Tensilon") under conditions of peeling speed of 300 mm / min and peeling angle of 180 degrees. Measurements under conditions other than those described here were performed in accordance with JIS Z0237:2022. The results are shown in Table 2.

[0163] For the adhesive sheet of Example 1, it was attached to soda-lime glass and subjected to pressurization in an autoclave, as described above. Then, the adhesive layer was irradiated with active energy rays (ultraviolet light; UV) through the PET film, and the adhesive strength (after UV) was measured after being left for 24 hours, as described above. The irradiation conditions for the active energy rays were the same as in Test Example 1. The results are shown in Table 2.

[0164] [Test Example 5] (Measurement of total light transmittance) The adhesive layers of the adhesive sheets manufactured in the examples and comparative examples were bonded to glass to serve as measurement samples. After background measurements were performed on the glass, the total light transmittance (%) of the measurement samples was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[0165] Furthermore, for the adhesive sheet of Example 1, after irradiating the adhesive layer with active energy rays (ultraviolet light; UV) through the glass of the measurement sample described above, the total light transmittance (%) was measured in the same manner as described above, and the measurement results were the same as described above. The irradiation conditions for the active energy rays were the same as in Test Example 1.

[0166] [Test Example 6] (Measurement of haze value) The adhesive layers of the adhesive sheets manufactured in the examples and comparative examples were bonded to glass, and these were used as measurement samples. After background measurements were performed on the glass, the haze value (%) of the measurement samples was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000. The results are shown in Table 2.

[0167] Furthermore, for the adhesive sheet of Example 1, after irradiating the adhesive layer with active energy rays (ultraviolet light; UV) through the glass of the measurement sample described above, the haze value (%) was measured in the same manner as described above, and the measurement results were the same as described above. The irradiation conditions for the active energy rays were the same as in Test Example 1.

[0168] [Test Example 7] (Measurement of dimensional change rate) Samples (MD and TD) measuring 5 mm wide x 30 mm long were cut from the adhesive layer of the adhesive sheets in the examples and comparative examples. For the adhesive sheet in Example 1, the adhesive layer was cured using active energy rays in the same manner as in Test Example 1.

[0169] Using a thermomechanical analyzer (manufactured by Netch Japan, instrument name "TMS4000SA"), the sample was placed with a chuck distance of 20 mm, then heated from 25°C to 130°C at a heating rate of 5°C / min, and then cooled to room temperature at 5°C / min (heat treatment process). The displacement in the longitudinal direction before and after the heat treatment process was measured, and the rate of change (the value expressed as a percentage of the displacement relative to the 20 mm chuck distance) was defined as the dimensional change rate (%). The measurement results of the dimensional change rate (%) in the MD and TD directions are shown in Table 2. Note that a negative value indicates that the sample contracted, and a positive value indicates that it expanded.

[0170] [Test Example 8] (Evaluation of laser cutting processability) The adhesive sheets produced in the examples and comparative examples were cut to a size of 100 mm x 100 mm and used as samples. For the adhesive sheet in Example 1, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0171] The edges of each side of the sample obtained above were laser-cut using a 30W CO2 laser system (Universal Laser Systems, Inc., Scottsdale, Arizona, product name "VLS2.30"), cutting 500 μm from the edge of each side. The laser cutting conditions were as follows: • Mode: Vector light Output 5% ·Speed ​​4% 150 PPI

[0172] After the laser cutting process described above, the edges of the samples were visually inspected to determine whether or not there was any leakage of adhesive, and the laser cutability was evaluated according to the following criteria. The results are shown in Table 2. ○...No leakage of adhesive or other substances was observed on the laser-cut sample edges. ×... Adhesive seepage was observed on the laser-cut edge of the sample.

[0173] [Test Example 9] (Evaluation of Adhesion) For the laser-cut sample in Test Example 8, the edge of the sample was visually inspected to determine whether there was any lifting or peeling at the interface between the glass plate and the adhesive layer. If there was no lifting or peeling, the edge of the sample was rubbed 10 times with a finger, and the presence of lifting or peeling was checked again, and the adhesion was evaluated according to the following criteria. The results are shown in Table 2. ◎...No lifting or peeling occurred. ○...Slight lifting and peeling occurred near the end face of the sample, but this did not pose any practical problems. ×...Significant lifting and peeling occurred.

[0174] [Table 1]

[0175] [Table 2]

[0176] As can be seen from Table 2, the adhesive sheets manufactured in the examples exhibited excellent laser-cutting properties. Furthermore, even after laser cutting, they maintained excellent adhesion to the substrate. [Industrial applicability]

[0177] The adhesive sheet according to the present invention can be suitably used in the manufacture of unit panels that constitute a tiling display. [Explanation of symbols]

[0178] 1…Adhesive sheet 11…Adhesive layer 12a, 12b… Release sheets 2... Unit Panel 21…Light-emitting substrate 22…Surface base material

Claims

1. An adhesive sheet used in the manufacture of unit panels that make up a tiling display, It has an adhesive layer, The adhesive constituting the aforementioned adhesive layer is an adhesive containing epoxy resin or a polyester-based adhesive. An adhesive sheet characterized by the following features.

2. The adhesive sheet according to claim 1, characterized in that the gel fraction of the adhesive constituting the adhesive layer is 20% or more and 99% or less.

3. The adhesive containing the epoxy resin, Epoxy resin with a Tg of 50°C or higher, An epoxy resin that yields a cured product with a Tg of 25°C or less, Cationic polymerization initiator and It is an active energy ray curable adhesive containing The adhesive sheet according to feature 1.

4. The aforementioned polyester-based adhesive, A polyester polymer having reactive functional groups, Crosslinking agent and The adhesive sheet according to claim 1, characterized in that it is formed by crosslinking an adhesive composition containing the above.

5. The aforementioned polyester-based adhesive, A polyester polymer having reactive functional groups, Crosslinking agent and Activated energy ray curing component and This adhesive composition is obtained by crosslinking and curing with active energy rays. The adhesive sheet according to feature 1.

6. The adhesive sheet according to claim 1, characterized in that the thickness of the adhesive layer is 1 μm or more and 500 μm or less.

7. The adhesive layer is provided with two release sheets to protect the adhesive surface, The adhesive layer is sandwiched between the two release sheets so as to be in contact with the release surfaces of the two release sheets. The adhesive sheet according to feature 1.

8. A unit panel that constitutes a tiling display, The adhesive sheet comprises an adhesive layer according to any one of claims 1 to 7. A unit panel characterized by the following features.

9. The unit panel according to claim 8, characterized in that the end face of the unit panel is laser-cut.

10. It comprises a surface substrate and a light-emitting substrate, The surface substrate or a laminate having the surface substrate and the light-emitting substrate or a laminate having the light-emitting substrate are bonded together by the adhesive layer. The unit panel according to feature 8.

11. The unit panel according to claim 10, characterized in that the light-emitting element of the light-emitting substrate is a mini-LED or a micro-LED.

12. A tiling display comprising multiple unit panels as described in claim 8, connected together.

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