Adhesive sheets, unit panels, and tiling displays

Abstract

This invention provides adhesive sheets, unit panels, and tiling displays that offer excellent laser-cutting properties and superior adhesion. [Solution] An adhesive sheet 1 used in the manufacture of a unit panel 2 constituting a tiling display, comprising a first adhesive layer 12, a second adhesive layer 13, and a core material 14 provided between the first adhesive layer 12 and the second adhesive layer 13, wherein the adhesive laminate 11 consisting of the first adhesive layer 12, the core material 14 and the second adhesive layer 13 is subjected to a torsional shear test in accordance with JIS K7244-6, where a pressure of 10kPa is applied for 600 seconds at a temperature of 23°C and a frequency of 1Hz, the strain is 120% or less, and the adhesive strength of the first adhesive layer 12 and the second adhesive layer 13 to soda-lime glass is 5N / 25mm or more each.

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, problems arise such as adhesive seeping out from the edges, and lifting or peeling occurring at the interface between the adhesive layer and the adherend.

[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 that have good laser-cutting properties and excellent adhesion. [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 a first adhesive layer, a second adhesive layer, and a core material provided between the first adhesive layer and the second adhesive layer, wherein the adhesive laminate consisting of the first adhesive layer, the core material, and the second adhesive layer exhibits a strain of 120% or less when a pressure of 10 kPa is applied for 600 seconds at a temperature of 23°C and a frequency of 1 Hz by a torsional shear method in accordance with JIS K7244-6, and the adhesive strength of the first adhesive layer and the second adhesive layer to soda-lime glass is 5 N / 25 mm or more, respectively (Invention 1).

[0008] Secondly, the present invention provides an adhesive sheet used in the manufacture of unit panels constituting a tiling display, comprising a first adhesive layer, a second adhesive layer, and a core material provided between the first adhesive layer and the second adhesive layer, wherein the gel fractions of the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are 30% or more and 99% or less, respectively, and the adhesive strength of the first adhesive layer and the second adhesive layer to soda-lime glass is 5N / 25mm or more, respectively (Invention 2).

[0009] The adhesive laminate in the above invention (Invention 1) has a predetermined hardness and adhesive strength by satisfying the above physical properties. Furthermore, the adhesive laminate in the above invention (Invention 2) has a predetermined cohesive force and adhesive strength by satisfying the above physical properties. As a result, when the end of a unit panel having the adhesive laminate is laser-cut to form a flat end surface, the leakage of adhesive from the end surface is suppressed, and the occurrence of lifting or peeling at the interface between the adhesive laminate and the adherend is suppressed.

[0010] In the above invention (Invention 1), it is preferable that the gel fractions of the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are 30% or more and 99% or less, respectively (Invention 3).

[0011] In the above inventions (Inventions 1 to 3), it is preferable that the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are both acrylic adhesives (Invention 4).

[0012] In the above inventions (Inventions 1 to 4), it is preferable that the thickness of the first adhesive layer and the second adhesive layer are 1 μm or more and 100 μm or less, respectively, and the thickness of the core material is 1 μm or more and 300 μm or less (Invention 5).

[0013] In the above inventions (Inventions 1 to 5), it is preferable that the core material is made of a plastic film (Invention 6).

[0014] In the above inventions (Inventions 1 to 6), it is preferable to include a release sheet that protects the adhesive surface of the first adhesive layer and a release sheet that protects the adhesive surface of the second adhesive layer (Invention 7).

[0015] Secondly, the present invention provides a unit panel constituting a tiling display, characterized in that it comprises an adhesive laminate consisting of the first adhesive layer, the core material, and the second adhesive layer of the adhesive sheet (Inventions 1 to 7) (Invention 8).

[0016] In the above invention (Invention 8), it is preferable that the end face of the unit panel is laser-cut (Invention 9).

[0017] In the above inventions (Inventions 8 and 9), it includes a surface base material and a light-emitting body substrate, and it is preferable that the surface base material or the laminate having the surface base material and the light-emitting body substrate or the laminate having the light-emitting body substrate are bonded by the adhesive laminate (Invention 10).

[0018] In the above invention (Invention 10), it is preferable that the light-emitting body of the light-emitting body substrate is a mini LED or a micro LED (Invention 11).

[0019] Thirdly, the present invention provides a tiling display formed by joining a plurality of the unit panels (Inventions 8 to 11) (Invention 12).

Effect of the Invention

[0020] The adhesive sheet, unit panel, and tiling display according to the present invention have good laser-cut processability and excellent adhesion.

Brief Description of the Drawings

[0021] [Figure 1] It is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view of a unit panel according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0022] 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 constituting a tiling display. An example of the adhesive sheet according to an embodiment of the present invention is shown in FIG. 1.

[0023] As shown in Figure 1, an adhesive sheet 1 according to one embodiment of the present invention comprises an adhesive laminate 11 consisting of a first adhesive layer 12, a second adhesive layer 13, and a core material 14 provided between the first adhesive layer 12 and the second adhesive layer 13. In this embodiment, a release sheet 16a is laminated to the adhesive surface 12S of the first adhesive layer 12 so as to be in contact with the release surface of the release sheet 16a, and a release sheet 16b is laminated to the adhesive surface 13S of the second adhesive layer 13 so as to be in contact with the release surface of the release sheet 16b.

[0024] In this specification, the adhesive surface of the adhesive layer refers to the surface of the adhesive layer that is in contact with the desired substrate and is attached to it. In this specification, the release surface of the release sheet refers to the surface of the release sheet that has release properties, and includes both surfaces that have undergone a release treatment and surfaces that exhibit release properties even without a release treatment.

[0025] The release sheets 16a and 16b described above protect the adhesive surfaces of the first adhesive layer 12 and the second adhesive layer 13 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 16a and 16b are not necessarily required.

[0026] For the adhesive laminate 11 (or the adhesive laminate after active energy ray curing if the adhesive layers are curable with active energy rays) consisting of the first adhesive layer 12, core material 14, and second adhesive layer 13 of the adhesive sheet 1, it is preferable that 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 120% or less. Alternatively, it is preferable that the gel fractions of the adhesive constituting the first adhesive layer 12 and the adhesive constituting the second adhesive layer 13 of the adhesive sheet 1 are 30% or more and 99%, respectively. Furthermore, it is preferable that the adhesive strength of the first adhesive layer 12 and the second adhesive layer 13 to soda-lime glass is 5 N / 25 mm or more, respectively. It is preferable that the adhesive sheet 1 satisfies either the above creep strain or gel fraction, but it is more preferable that it satisfies both.

[0027] Herein, the details of the creep strain measurement method in this specification are as shown in the test examples described later. The gel fraction measurement method in this specification is as shown in the test examples described later. Furthermore, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2022, but the measurement sample shall be 25 mm wide and 100 mm long, the measurement sample shall be attached to the adherend, 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 then measured at a peeling speed of 300 mm / min. Note that in this specification, "relative humidity α%" may be expressed as "α%RH" (RH; Relative humidity).

[0028] The adhesive laminate 11 has a predetermined hardness by satisfying the above-mentioned creep strain. Furthermore, the adhesive laminate 11 has a predetermined cohesive force by satisfying the above-mentioned gel fraction. As a result, when the end of a unit panel having the adhesive laminate 11 is laser-cut to form a flat end face, the leakage of adhesive from the end face is suppressed. Thus, the adhesive sheet 1 according to this embodiment has excellent laser-cutting processability. In addition, by satisfying the above-mentioned adhesive force, the adhesive laminate 11 is less prone to lifting and peeling at the interface between the first adhesive layer 12 and the adherend (e.g., light-emitting substrate) and the interface between the second adhesive layer 13 and the adherend (e.g., surface substrate) during laser cutting, resulting in excellent adhesion.

[0029] In a tiling display, which is made by joining together multiple laser-cut unit panels as described above, there are virtually no gaps between the unit panels, resulting in uniform brightness and high image quality.

[0030] From the viewpoint of laser-cuttable properties, the creep strain of the adhesive laminate 11 is more preferably 100% or less, particularly preferably 90% or less, even more preferably 80% or less, and most preferably 70% or less. The lower limit of the creep strain is preferably 0.1% or more, more preferably 1% or more, particularly preferably 4% or more, and even more preferably 8% or more, considering the adhesiveness.

[0031] Furthermore, from the viewpoint of laser-cut machinability, the gel fraction of the adhesive constituting the adhesive layers 12 and 13 is more preferably 35 to 90%, particularly preferably 40 to 80%, even more preferably 44 to 75%, and among these, 48 to 70%, and especially preferably 52 to 65%.

[0032] When the adhesive constituting the adhesive layers 12 and 13 is curable by active energy rays, the gel fraction after curing by active energy rays is preferably 30-99%, more preferably 40-94%, particularly preferably 50-90%, even more preferably 60-86%, and most preferably 70-82%. This results in superior laser cutting properties.

[0033] From the viewpoint of adhesion, the adhesive strength of the first adhesive layer 12 and the second adhesive layer 13 to the soda-lime glass is more preferably 10 N / 25 mm or more, particularly preferably 15 N / 25 mm or more, even more preferably 20 N / 25 mm or more, and most preferably 25 N / 25 mm or more. On the other hand, the upper limit of the adhesive strength is preferably 100 N / 25 mm or less, more preferably 75 N / 25 mm or less, particularly preferably 50 N / 25 mm or less, and most preferably 40 N / 25 mm or less. When the upper limit of the adhesive strength is as described above, good reworkability is obtained, and if a bonding error occurs, the adherend can be reused.

[0034] Here, if the first adhesive layer 12 or the second adhesive layer 13 is curable by active energy rays, the adhesive strength after the adhesive surface 12S of the first adhesive layer 12 of the adhesive sheet 1 is attached to soda-lime glass and the first adhesive layer 12 is cured by active energy rays (adhesive strength after active energy ray curing), or the adhesive strength after the adhesive surface 13S of the second adhesive layer 13 of the adhesive sheet 1 is attached to soda-lime glass and the second adhesive layer 13 is cured by active energy rays (adhesive strength after active energy ray curing), is preferably 5 N / 25 mm or more, more preferably 15 N / 25 mm or more, particularly preferably 25 N / 25 mm or more, even more preferably 30 N / 25 mm or more, and most preferably 35 N / 25 mm or more. As a result, lifting and peeling are less likely to occur at the interface between the first adhesive layer 12, which has been cured with active energy rays, and the adherend (e.g., a light-emitting substrate), or at the interface between the second adhesive layer 13, which has been cured with active energy rays, and the adherend (e.g., a surface substrate), resulting in excellent adhesion.

[0035] Furthermore, the adhesive strength is preferably 100 N / 25 mm or less as an upper limit, more preferably 80 N / 25 mm or less, particularly preferably 60 N / 25 mm or less, and most preferably 50 N / 25 mm or less. When the upper limit of the adhesive strength is as described above, good reworkability is obtained, and if an adhesion error occurs, the adherend can be reused.

[0036] 1. Components 1-1. Adhesive layer The adhesives constituting the first adhesive layer 12 and the second adhesive layer 13 of the adhesive sheet 1 according to this embodiment may be any adhesives that satisfy the aforementioned creep strain or gel fraction and the aforementioned adhesive strength as an adhesive laminate 11 including the core material 14. Examples of such adhesives include acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone adhesives, etc., and among these, acrylic adhesives that easily satisfy the above creep strain or gel fraction are preferred.

[0037] As for the acrylic adhesive, a crosslinked type is preferred, and a thermally crosslinked type is even more preferred. Furthermore, the acrylic adhesive used in this embodiment may be non-curable by active energy rays or curable by active energy rays. From the perspective of SDGs, the materials constituting the adhesive may be materials with a high biomass content, materials that can be recycled or reused, or recycled or reused materials.

[0038] In this embodiment, the adhesive is preferably a crosslinked adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B). The adhesive obtained by crosslinking adhesive composition P is more likely to satisfy the aforementioned physical properties. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "polymer" is also included in the concept of "polymer".

[0039] (1) Components of adhesive composition P (1-1)(meth)acrylic acid ester polymer (A) In this embodiment, the (meth)acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a monomer unit constituting the polymer, which has a reactive group in its molecule that reacts with the crosslinking agent (B). The reactive group derived from this reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and an adhesive having the desired cohesive force is obtained.

[0040] Preferred reactive group-containing monomers include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers) and monomers having a carboxyl group in the molecule (carboxyl group-containing monomers). Among these, hydroxyl group-containing monomers or carboxyl group-containing monomers that exhibit excellent reactivity with the crosslinking agent (B) are preferred, and hydroxyl group-containing monomers are particularly preferred.

[0041] Examples of hydroxyl group-containing monomers include hydroxyalkyl esters of (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, hydroxyalkyl esters of (meth)acrylates having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred from the viewpoint of reactivity with crosslinking agent (B) and copolymerizability with other monomers. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

[0042] The (meth)acrylic acid ester polymer (A) preferably contains 1 to 40% by mass of reactive group-containing monomers as monomer units constituting the polymer, more preferably 6 to 36% by mass, particularly preferably 12 to 32% by mass, even more preferably 18 to 28% by mass, and most preferably 20 to 26% by mass. This results in an adhesive having high cohesive force, making it easier to satisfy the aforementioned creep strain and gel fraction.

[0043] Furthermore, it is preferable that the (meth)acrylic acid ester polymer (A) does not contain carboxyl group-containing monomers as monomer units constituting the polymer. Since carboxyl groups are acidic components, by not containing carboxyl group-containing monomers, it is possible to suppress defects in the adherends of the adhesive that may be affected by acid. However, it is permissible to include a predetermined amount of carboxyl group-containing monomers to the extent that such defects do not occur. Specifically, it is permissible to include carboxyl group-containing monomers as monomer units in the (meth)acrylic acid ester polymer (A) in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

[0044] The (meth)acrylic acid ester polymer (A) preferably contains an alkyl (meth)acrylic acid ester as a monomer unit constituting the polymer. This allows for good tackiness. The alkyl group may be linear or branched.

[0045] From the viewpoint of adhesiveness, alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group are preferred. Examples of alkyl (meth)acrylate esters with 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. In particular, from the viewpoint of further improving adhesiveness and making it easier to satisfy the aforementioned physical properties, (meth)acrylic acid esters with 4 to 8 carbon atoms in the alkyl group are preferred, with n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate being especially preferred, and n-butyl acrylate, 2-ethylhexyl acrylate, or isooctyl acrylate being even more preferred. These may be used individually or in combination of two or more.

[0046] The (meth)acrylic acid ester polymer (A) preferably contains 30 to 99% by mass of alkyl (meth)acrylic acid ester as the monomer units constituting the polymer, more preferably 40 to 90% by mass, particularly preferably 45 to 80% by mass, and even more preferably 50 to 70% by mass. This makes it easier to satisfy the aforementioned adhesive strength and allows for the introduction of suitable amounts of other monomer components, such as monomers containing reactive functional groups, into the (meth)acrylic acid ester polymer (A), making it easier to satisfy the aforementioned creep strain and gel fraction.

[0047] The (meth)acrylic acid ester polymer (A) may also preferably contain monomers having an alicyclic structure within the molecule (alicyclic structure-containing monomers) as monomer units constituting the polymer. This makes it easier to satisfy the aforementioned physical properties.

[0048] In monomers containing an alicyclic structure, the carbon ring of the alicyclic structure may be a saturated structure or may have some unsaturated bonds. Furthermore, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic structure. From the viewpoint of appropriately regulating the distance between the resulting (meth)acrylic acid ester polymers (A), it is preferable that the alicyclic structure be a polycyclic structure. Furthermore, considering the compatibility between the (meth)acrylic acid ester polymers (A) and other components, it is particularly preferable that the polycyclic structure be bicyclic to tetracyclic. Also, from the same viewpoint as above, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the ring-forming portion, and the total number of carbon atoms if multiple rings exist independently) is preferably 5 to 15, and particularly preferably 7 to 10.

[0049] Examples of monomers containing an alicyclic structure include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among these, dicyclopentanyl (meth)acrylate (10 carbon atoms in the alicyclic structure), adamantyl (10 carbon atoms in the alicyclic structure), or isobornyl (7 carbon atoms in the alicyclic structure) are preferred from the viewpoint of easily satisfying the aforementioned physical properties, with isobornyl (meth)acrylate being particularly preferred, and isobornyl acrylate being even more preferred. These may be used individually or in combination of two or more.

[0050] When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it is preferable from the viewpoint of easily satisfying the aforementioned physical properties that the alicyclic structure-containing monomer contains 1 to 40% by mass, more preferably 4 to 32% by mass, particularly preferably 8 to 24% by mass, and even more preferably 12 to 16% by mass.

[0051] The (meth)acrylic acid ester polymer (A) may also preferably contain a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By including a nitrogen atom-containing monomer as a constituent unit in the polymer, a predetermined polarity can be imparted to the adhesive, making it highly compatible with adherends that have a certain degree of polarity, such as glass. From the viewpoint of giving the (meth)acrylic acid ester polymer (A) appropriate rigidity, a monomer having a nitrogen-containing heterocycle is preferred as the nitrogen atom-containing monomer. Furthermore, from the viewpoint of increasing the degree of freedom of the nitrogen atom-containing monomer-derived portion in the higher-order structure of the adhesive, it is preferable that the nitrogen atom-containing monomer does not contain any reactive unsaturated double bond groups other than the one polymerizable group used for polymerization to form the (meth)acrylic acid ester polymer (A).

[0052] Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine is preferred because it exhibits superior adhesive strength, and N-acryloylmorpholine is particularly preferred. These may be used individually or in combination of two or more.

[0053] When the (meth)acrylic acid ester polymer (A) contains nitrogen atom-containing monomers as monomer units constituting the polymer, it is preferable that it contains 1 to 30% by mass of the nitrogen atom-containing monomers, more preferably 2 to 20% by mass, particularly preferably 3 to 12% by mass, and even more preferably 4 to 8% by mass. This makes it easier for the resulting adhesive to satisfy the aforementioned creep strain and adhesive strength.

[0054] The (meth)acrylic acid ester polymer (A) may optionally contain other monomers as monomer units constituting the polymer. Among the other monomers, monomers that do not contain reactive functional groups are preferred in order not to inhibit the aforementioned effects of the reactive functional group-containing monomers. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used individually or in combination of two or more.

[0055] The (meth)acrylic acid ester polymer (A) is preferably a linear polymer. Being a linear polymer makes it easier for molecular chains to intertwine, which can be expected to improve cohesiveness.

[0056] The (meth)acrylic acid ester polymer (A) may be polymerized in solution, without solvents, or by emulsion polymerization. Among these, a solution polymer obtained by solution polymerization is preferred from the viewpoint of easily obtaining a high molecular weight polymer and an adhesive with excellent durability.

[0057] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0058] The weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,600,000, particularly preferably 300,000 to 1,200,000, even more preferably 400,000 to 900,000, and most preferably 450,000 to 700,000. This makes it easier to satisfy the aforementioned physical properties. Here, the weight-average molecular weight as used herein is the value on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0059] In addition, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more types.

[0060] The content of the (meth)acrylic acid ester polymer (A) in the adhesive composition P according to this embodiment is preferably 60 to 99.9% by mass, more preferably 65 to 99.5% by mass, particularly preferably 70 to 99% by mass, and even more preferably 75 to 98% by mass. This makes it easier to satisfy the aforementioned physical properties.

[0061] (1-2) Crosslinking agent (B) The crosslinking agent (B) can be any agent that is capable of reacting with the reactive groups of the (meth)acrylic acid ester polymer (A). Examples of crosslinking agents (B) include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, ammonium salt crosslinking agents, etc. Crosslinking agent (B) can be used alone or in combination of two or more types.

[0062] When the reactive group of the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that has high reactivity with the hydroxyl group.

[0063] 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.

[0064] The amount of crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 2 parts by mass, more preferably 0.04 to 1 part by mass, particularly preferably 0.07 to 0.5 parts by mass, and even more preferably 0.1 to 0.2 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A). This makes it easier to obtain an adhesive with desirable cohesive strength and tackiness, and to satisfy the aforementioned physical properties.

[0065] (1-3) Silane coupling agent (C) The adhesive composition P preferably further contains a silane coupling agent (C). This improves adhesion to the adherend and makes it easier to achieve the aforementioned adhesive strength.

[0066] The silane coupling agent (C) is preferably an organosilicon compound having at least one alkoxysilyl group in its molecule, which has good compatibility with the (meth)acrylic acid ester polymer (A) and is light-transmitting.

[0067] Examples of silane coupling agents (C) 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.

[0068] The content of the silane coupling agent (C) in the adhesive composition P 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 the (meth)acrylic acid ester polymer (A). This makes it easier to satisfy the aforementioned adhesive strength.

[0069] (1-4) Active energy ray curing component (D) The adhesive composition P may also preferably contain an active energy ray curable component (D). This results in an adhesive that is curable by active energy rays. The adhesive laminate 11 containing the active energy ray curable component (D) and the adhesive that has been cured by active energy rays exhibits less creep strain, a larger gel fraction, and superior laser cutting properties. Furthermore, the adhesive strength after active energy ray curing is greater.

[0070] The active energy ray curable component (D) is not particularly limited as long as it 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.

[0071] 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 reducing creep strain after active energy ray curing, increasing gel fraction, and increasing adhesive strength, polyfunctional acrylate monomers containing an isocyanurate structure in the molecule, such as di(acryloxyethyl) isocyanurate, tris(acryloxyethyl) isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate, are preferred, polyfunctional acrylate monomers with three or more functions and containing an isocyanurate structure in the molecule are more preferred, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate is particularly 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 (meth)acrylic acid ester polymer (A), 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.

[0072] The content of the active energy ray curable component (D) in the adhesive composition P is preferably 1 to 20 parts by mass, particularly preferably 3 to 12 parts by mass, and even more preferably 4 to 8 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer (A), from the viewpoint of reducing creep strain after active energy ray curing, increasing the gel fraction, and increasing adhesive strength.

[0073] (1-5) Photopolymerization initiator (E) When the adhesive composition P contains an active energy ray-curable component (D) and ultraviolet light is used as the active energy ray, it is preferable to include a photopolymerization initiator (E). This allows for efficient curing of the active energy ray-curable component (D), resulting in smaller creep strain and a larger gel fraction after active energy ray curing. Furthermore, the polymerization curing time and the amount of ultraviolet light irradiation can be reduced.

[0074] Examples of photopolymerization initiators (E) 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.

[0075] The content of the photopolymerization initiator (E) in the adhesive composition P is preferably 2 to 20 parts by mass, particularly preferably 4 to 18 parts by mass, and even more preferably 6 to 15 parts by mass, per 100 parts by mass of the active energy ray curable component (D). This makes it possible to reduce creep strain and increase the gel fraction after active energy ray curing.

[0076] (1-6) Various additives The adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as fillers, colorants, ultraviolet absorbers, infrared absorbers, refractive index adjusters, antistatic agents, tackifiers, rust inhibitors, antioxidants, light stabilizers, and oxygen absorbers. The polymerization solvent and diluent solvent described later are not included in the additives constituting the adhesive composition P.

[0077] (1-6-1) Filler When the adhesive composition P contains light-diffusing microparticles as a filler, it becomes easier to suppress brightness unevenness and to adjust the emission color of the light source to a desired color. Examples of light-diffusing microparticles include inorganic light-diffusing microparticles such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide; organic light-diffusing microparticles such as acrylic resins, polystyrene resins, polyethylene resins, epoxy resins, copolymers or mixtures thereof; light-diffusing microparticles made of silicon-containing compounds having an intermediate structure between inorganic and organic, such as silicone resin (e.g., the Tospar series from Momentive Performance Materials Japan); and hybrid light-diffusing microparticles of organic resins and silicone resins. Among these, light-diffusing microparticles made of silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) are preferred. This makes it easier to obtain the above effects. The above light-diffusing microparticles may be used individually or in combination of two or more types.

[0078] As for the shape of the light-diffusing particles, spherical light-diffusing particles with uniform light diffusion are preferred, and perfectly spherical light-diffusing particles are particularly preferred, but the invention is not limited thereto.

[0079] The average particle size of the light-diffusing fine particles (average particle size measured by centrifugal sedimentation light transmission method) is preferably 0.5 to 20 μm, more preferably 1 to 15 μm, particularly preferably 2 to 11 μm, even more preferably 3 to 8 μm, and most preferably 4 to 6 μm.

[0080] The average particle size obtained by the centrifugal sedimentation light transmission method described above was measured using a centrifugal automatic particle size distribution analyzer (Horiba, Ltd., product name "CAPA-700"), with a sample prepared by thoroughly stirring 1.2 g of light-diffusing fine particles and 98.8 g of isopropyl alcohol.

[0081] The refractive index of the light-diffusing fine particles is preferably 1.30 to 2.00, more preferably 1.35 to 1.85, particularly preferably 1.40 to 1.65, and even more preferably 1.42 to 1.55. The refractive index of the light-diffusing fine particles can be determined by Method B of JIS K7142:2008.

[0082] If the adhesive composition P contains light-diffusing fine particles, the amount is preferably 1 to 40 parts by mass, more preferably 3 to 32 parts by mass, particularly preferably 5 to 24 parts by mass, and even more preferably 7 to 18 parts by mass, per 100 parts by mass of (meth)acrylic acid ester polymer (A).

[0083] (1-6-2) Colorants If the adhesive composition P contains a coloring agent, the first adhesive layer 12 or the second adhesive layer 13 can be given a desired color. This makes it possible to obtain a desired appearance and light transmittance.

[0084] The coloring agent may be a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. The dye may be a natural dye or a synthetic dye. The color of the coloring agent can be selected as appropriate depending on the purpose.

[0085] Examples of inorganic pigments include carbon black pigments, cobalt dyes, iron dyes, chromium dyes, titanium dyes, vanadium dyes, zirconium dyes, molybdenum dyes, ruthenium dyes, platinum dyes, ITO (indium tin oxide) dyes, and ATO (antimony tin oxide) dyes.

[0086] Examples of organic pigments and dyes include aminium-based dyes, cyanine-based dyes, merocyanine-based dyes, croconium-based dyes, squalium-based dyes, azulenium-based dyes, polymethine-based dyes, naphthoquinone-based dyes, pyririum-based dyes, phthalocyanine-based dyes, naphthalocyanine-based dyes, naphtholactam-based dyes, azo-based dyes, condensed azo-based dyes, indigo-based dyes, perinone-based dyes, perylene-based dyes, dioxazine-based dyes, quinacridone-based dyes, isoindolone-based dyes, quinophthalone-based dyes, pyrrole-based dyes, thioindigo-based dyes, metal complex-based dyes (metal complex salt dyes), dithiol metal complex-based dyes, indolephenol-based dyes, triallylmethane-based dyes, anthraquinone-based dyes, dioxazine-based dyes, naphthol-based dyes, azomethine-based dyes, benzimidazolone-based dyes, pyranthrone-based dyes, and surene-based dyes.

[0087] Examples of black pigments include carbon black, copper oxide, iron(II,III) oxide, manganese dioxide, aniline black, and activated carbon. Examples of black dyes include high-concentration plant-based dyes and azo dyes.

[0088] Furthermore, the above-mentioned pigments or dyes can be mixed and used as appropriate depending on the purpose.

[0089] From the viewpoint of optical properties, the coloring agent preferably satisfies the following characteristics. By using an appropriate amount of a coloring agent that satisfies the following characteristics, it is easier to obtain an adhesive sheet that exhibits the desired optical properties.

[0090] The coloring agent is a solution obtained by diluting the coloring agent 10,000 times with ethyl acetate, with a wavelength of 780 nm. The average haze, which is the average of the haze value at [location] and the haze value at a wavelength of 380 nm, is preferably 1-60%, more preferably 2-40%, particularly preferably 3-30%, even more preferably 3.5-20%, and most preferably 4-10%.

[0091] The coloring agent is a solution obtained by diluting the coloring agent 10,000 times with ethyl acetate, with a wavelength of 780 nm. The difference between the haze value at [location] and the haze value at a wavelength of 380 nm is preferably 0 to 30 points, more preferably 1 to 20 points, particularly preferably 2 to 10 points, and even more preferably 3 to 8 points.

[0092] The coloring agent preferably has a haze value at a wavelength of 780 nm of 0.1 to 50% of the solution obtained by diluting the coloring agent 10,000 times with ethyl acetate, more preferably 0.5 to 30%, particularly preferably 1 to 20%, and even more preferably 2 to 10%. Furthermore, the haze value at a wavelength of 380 nm of the solution obtained by diluting the coloring agent 10,000 times with ethyl acetate is preferably 1 to 60%, more preferably 3 to 40%, particularly preferably 6 to 30%, and even more preferably 10 to 20%.

[0093] The standard deviation of the haze value of the coloring agent, when the coloring agent is diluted 10,000 times with ethyl acetate, at each wavelength in the wavelength range of 380 nm to 780 nm at 5 nm intervals (i.e., 380 nm, 385 nm, 390 nm, ..., 775 nm, 780 nm), is preferably 0.1 to 10, more preferably 0.4 to 7, particularly preferably 0.8 to 4, and even more preferably 1 to 2.

[0094] If the adhesive composition P contains a coloring agent (especially a pigment), the amount is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, particularly preferably 0.1 to 2 parts by mass, even more preferably 0.15 to 1.5 parts by mass, and most preferably 0.2 to 1 part by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer (A).

[0095] (2) Preparation of adhesive composition P The adhesive composition P can be produced by manufacturing a (meth)acrylic acid ester polymer (A), mixing the obtained (meth)acrylic acid ester polymer (A) with a crosslinking agent (B), and optionally adding a silane coupling agent (C), an active energy ray curable component (D), a photopolymerization initiator (E), additives, etc.

[0096] (Meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a conventional radical polymerization method. Polymerization of (meth)acrylic acid ester polymer (A) is preferably carried out by solution polymerization using a polymerization initiator if desired. However, the present invention is not limited thereto, and polymerization may also be carried out without a solvent. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc., and two or more types may be used in combination.

[0097] Examples of polymerization initiators include azo compounds and organic peroxides, and two or more may be used in combination. Furthermore, the weight-average molecular weight of the resulting polymer can be adjusted by incorporating a chain transfer agent such as 2-mercaptoethanol during the polymerization process.

[0098] Once the (meth)acrylic acid ester polymer (A) is obtained, a crosslinking agent (B), and optionally a silane coupling agent (C), an active energy ray curable component (D), a photopolymerization initiator (E), additives, a diluent, etc., are added to the solution of the (meth)acrylic acid ester polymer (A), and thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution). If any of the above components are used in solid form, or if precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted in a diluent beforehand before mixing with the other components.

[0099] 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.

[0100] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited, as long as they are within the range of coating, and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 60% by mass. Note that the addition of a diluent is not a necessary condition when obtaining the coating solution; if the adhesive composition P has a viscosity suitable for coating, a diluent may not be added. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent of the (meth)acrylic acid ester polymer (A) is used directly as the diluent.

[0101] (3) Formation of the adhesive layer In this embodiment, the first adhesive layer 12 and the second adhesive layer 13 preferably consist of an adhesive obtained by crosslinking the adhesive composition P (coating layer). Crosslinking of the adhesive composition P can usually be performed by heat treatment. This heat treatment can also be combined with the drying treatment used to volatilize the diluent solvent, etc., from the coating layer of the adhesive composition P applied to the desired object.

[0102] 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.

[0103] After heat treatment, a curing period of 1 to 2 weeks at room temperature (e.g., 23°C, 50% RH) may be allowed if necessary. If a curing period is required, the adhesive will be formed after the curing period has elapsed; if a curing period is not required, the adhesive will be formed after the heat treatment is completed.

[0104] Through the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is crosslinked via the crosslinking agent (B), and an adhesive is obtained.

[0105] Furthermore, if the adhesive composition P contains an active energy ray-curable component (D), it is preferable to apply the adhesive layer to the substrate before irradiation with active energy rays, and then irradiate it with active energy rays. This increases the adhesive force to the substrate and results in better adhesion.

[0106] (4) Thickness of the adhesive layer The thickness of the first adhesive layer and the second adhesive layer (measured according to JIS K7130) is preferably 1 to 100 μm, more preferably 10 to 96 μm, particularly preferably 20 to 92 μm, even more preferably 30 to 90 μm, and most preferably 40 to 88 μm. This makes it easier to satisfy the aforementioned creep strain while maintaining the desired adhesive strength.

[0107] 1-2. Core material The core material 14 can be any adhesive laminate 11 including a first adhesive layer 12 and a second adhesive layer 13 that satisfies the aforementioned creep strain, and is preferably made of a plastic film.

[0108] Examples of plastic films include polyester films made from polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyurethane films; polyethylene films; polypropylene films; cellulose films such as triacetylcellulose; polyvinyl chloride films; polyvinylidene chloride films; polyvinyl alcohol films; ethylene-vinyl acetate copolymer films; polystyrene films; polycarbonate films; acrylic resin films; norbornene-based resin films; cycloolefin resin films; and laminates of two or more of these. The plastic film may be uniaxially oriented or biaxially oriented. Among these, polyester films are preferred, and polyethylene terephthalate films are particularly preferred. With this plastic film, the aforementioned creep strain is more easily satisfied.

[0109] Furthermore, from an SDG perspective, the core material may be made from materials with a high biomass content, materials that can be recycled or reused, or materials that have already been recycled or reused.

[0110] In the core material 14 made of the plastic film described above, surface treatment by oxidation or primer treatment can be applied to one or both sides as desired, for purposes such as improving adhesion with the adjacent first adhesive layer 12 and / or second adhesive layer 13. Examples of oxidation methods include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment. These surface treatment methods are appropriately selected depending on the type of plastic film, but corona discharge treatment is generally preferred in terms of effectiveness and ease of operation.

[0111] The thickness of the core material 14 is preferably 1 to 300 μm, more preferably 10 to 250 μm, particularly preferably 15 to 200 μm, even more preferably 20 to 150 μm, and most preferably 25 to 120 μm. This makes it easier to satisfy the aforementioned creep strain.

[0112] The tensile strength (breaking stress) of the core material 14 is preferably 10 to 10,000 MPa, more preferably 50 to 5,000 MPa, particularly preferably 100 to 1,000 MPa, and even more preferably 200 to 500 MPa in the MD (direction of the manufacturing line). Furthermore, the TD (direction perpendicular to the MD) is preferably 10 to 10,000 MPa, more preferably 50 to 5,000 MPa, particularly preferably 100 to 1,000 MPa, and even more preferably 200 to 500 MPa. The tensile strength (breaking stress) of the core material shall be measured by the same method as the tensile test in the test example described later.

[0113] The elongation of the core material 14 is preferably MD is 10-1000%, more preferably 50-600%, particularly preferably 80-400%, and even more preferably 100-200%. Similarly, the TD is preferably 10-1000%, more preferably 40-600%, particularly preferably 70-400%, and even more preferably 90-200%. The method for measuring the elongation of the core material conforms to JIS C2318.

[0114] The dimensional change rate of the core material 14 due to heating (a negative value indicates shrinkage, and a positive value indicates expansion) is preferably MD is 0.1 to 5%, more preferably 0.15 to 3%, particularly preferably 0.2 to 2%, and even more preferably 0.25 to 1%. Similarly, TD is preferably 0.1 to 5%, more preferably 0.15 to 3%, particularly preferably 0.2 to 2%, and even more preferably 0.25 to 1%. The dimensional change rate of the core material shall be measured by the same method as the dimensional change rate measurement method in the test examples described later.

[0115] As the core material 14, commercially available products can be used, and for example, "Cosmoshine (registered trademark) A4360 100μm" manufactured by Toyobo Co., Ltd. can be preferably used.

[0116] 1-3. Release Sheet Examples of release sheets 16a and 16b 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.

[0117] It is preferable that the release surfaces of the release sheets 16a and 16b (especially the surfaces in contact with the adhesive layers 12 and 13) 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.

[0118] There are no particular restrictions on the thickness of the release sheets 16a and 16b, but they are usually preferably 10 to 250 μm, and particularly preferably 20 to 150 μm.

[0119] In the two release sheets 16a and 16b 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.

[0120] 2. Manufacturing method As an example of manufacturing the adhesive sheet 1, the case in which the above-mentioned adhesive composition P is used will be described. In a preferred manufacturing example, a coating solution of the adhesive composition P for forming the first adhesive layer 12 is applied to the release surface of one release sheet 16a, and heat treatment is performed to thermally crosslink the adhesive composition P to form the first coating layer. Next, the core material 14 is laminated onto the coating layer. On the release surface of the other release sheet 16b, a coating solution of the adhesive composition P for forming the second adhesive layer 13 is applied, and heat treatment is performed to thermally crosslink the adhesive composition P to form the second coating layer. Then, the second coating layer is bonded to the core material 14 laminated onto the first coating layer. If a curing period is necessary, a curing period is performed; if a curing period is not necessary, the first coating layer becomes the first adhesive layer 12, and the second coating layer becomes the second adhesive layer 13. This gives the adhesive sheet 1. The conditions for heat treatment and curing are as described above.

[0121] Another manufacturing example of the adhesive sheet 1 involves applying a coating solution of the adhesive composition P for forming the first adhesive layer 12 to one side of the core material 14, and then performing a heat treatment to thermally crosslink the adhesive composition P to form the first coating layer. Then, a release sheet 16a is laminated to the first coating layer with its release surface in contact with it, forming the first laminate. On the other hand, a coating solution of the adhesive composition P for forming the second adhesive layer 13 is applied to the release surface of the release sheet 16b, and then performing a heat treatment to thermally crosslink the adhesive composition P to form the second coating layer, forming the second laminate. Next, the first laminate and the second laminate are bonded together so that the core material 14 of the first laminate and the second coating layer of the second laminate overlap. If a curing period is necessary, a curing period is allowed; if a curing period is not necessary, the first coating layer becomes the first adhesive layer 12, and the second coating layer becomes the second adhesive layer 13. This results in the adhesive sheet 1.

[0122] Methods for applying the coating solution of the above-mentioned adhesive composition P include, for example, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0123] 3.Physical properties etc. (1) Thickness of the adhesive laminate The thickness of the adhesive laminate 11 (measured according to JIS K7130) is preferably 1 to 500 μm, more preferably 25 to 420 μm, particularly preferably 50 to 360 μm, even more preferably 75 to 300 μm, and most preferably 100 to 250 μm. This makes it easier to satisfy the aforementioned creep strain and adhesive force.

[0124] (2) Elongation at break For an adhesive laminate 11 (or adhesive laminate after active energy ray curing if the adhesive layers are curable with active energy rays) consisting of a first adhesive layer 12, a core material 14, and a second adhesive layer 13 in the adhesive sheet 1, the elongation at break measured by a tensile test performed by stretching 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 ensures that the adhesive laminate 11 has a predetermined hardness. As a result, even when the edges of a unit panel having the adhesive laminate 11 are laser-cut to form a flat edge, the leakage of adhesive from the edge is suppressed. From the viewpoint of tackiness, the lower limit of the 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. The tensile test shall be conducted with a measurement width of 10 mm and a measurement length of 25 mm, under conditions of 23°C and 50% RH. The detailed test procedure is as shown in the test example described later.

[0125] The above-mentioned elongation at break is preferably satisfied both in the line direction (MD) during the manufacturing of the adhesive laminate 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 seepage of adhesive at each edge during laser cutting when the unit panel is rectangular, for example.

[0126] (3) Fracture stress For an adhesive laminate 11 (or adhesive laminate after active energy ray curing if the adhesive layers are curable with active energy rays) consisting of a first adhesive layer 12, a core material 14, and a second adhesive layer 13 in the adhesive sheet 1, the breaking stress measured by a tensile test performed by stretching 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 laminate 11 a predetermined hardness. As a result, even when the edges of a unit panel having the adhesive laminate 11 are laser-cut to form a flat edge, the leakage of adhesive from the edge is suppressed. From the viewpoint of adhesiveness, 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. The tensile test shall be conducted with a measurement width of 10 mm and a measurement length of 25 mm, under conditions of 23°C and 50% RH. The detailed test procedure is as shown in the test example described later.

[0127] The above fracture stress is preferably satisfied both in the line direction (MD) during the manufacturing of the adhesive laminate 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 seepage of adhesive at each edge during laser cutting when the unit panel is, for example, rectangular.

[0128] (4) Total light transmittance The total light transmittance of the adhesive laminate 11, which consists of a first adhesive layer 12, a core material 14, and a second adhesive layer 13 in 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 results in 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 layers 12 and 13 are 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.

[0129] (5) Haze value The haze value of the adhesive laminate 11, which consists of a first adhesive layer 12, a core material 14, and a second adhesive layer 13 in 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 results in 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. In the case of adhesive layers 12 and 13 that are 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.

[0130] (6) Dimensional change rate The dimensional change rate (negative value for shrinkage, positive value for expansion) due to heating of the adhesive laminate 11 (or the adhesive laminate after active energy ray curing if the adhesive layers are curable with active energy rays) in the adhesive sheet 1, consisting of a first adhesive layer 12, a core material 14, and a second adhesive layer 13, is ideally 0%, but in practice, it is preferably 0.01 to 10%, more preferably 0.05 to 7%, particularly preferably 0.1 to 4%, even more preferably 0.2 to 2%, and among these preferably 0.25 to 1.5%, and especially preferably 0.3 to 1%. As a result, the adhesive laminate 11 has a predetermined shape retention property. Consequently, even when the edges of a unit panel having the adhesive laminate 11 are laser-cut to form a flat edge, the leakage of adhesive from the edge is more effectively suppressed, and the occurrence of lifting, peeling, etc. at the interface with the adherend is more effectively suppressed. The method for measuring the dimensional change rate is as shown in the test examples described later.

[0131] [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.

[0132] As shown in Figure 2, the unit panel 2 according to this embodiment comprises a light-emitting substrate 21, a surface substrate 22, and an adhesive laminate 11 positioned between them to bond the light-emitting substrate 21 and the surface substrate 22. The adhesive laminate 11 comprises a first adhesive layer 12, a second adhesive layer 13, and a core material 14 provided between the first adhesive layer 12 and the second adhesive layer 13, and is obtained from the adhesive laminate 11 of the adhesive sheet 1 according to the above embodiment. In this embodiment, the adhesive surface 12S of the first adhesive layer 12 is in contact with the light-emitting substrate 21, and the adhesive surface 13S of the second adhesive layer 13 is in contact with the surface substrate 22.

[0133] Furthermore, if the first adhesive layer 12 and the second adhesive layer 13 of the adhesive sheet 1 are composed of an active energy ray-curable adhesive, then the first adhesive layer 12 and the second adhesive layer 13 in the unit panel 2 are in the state after active energy ray curing.

[0134] The shape of unit panel 2 in plan view is usually rectangular, but is not limited to this, and may be any desired polygon.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] To manufacture the unit panel 2, as an example, one release liner 16b of the adhesive sheet 1 is peeled off, and the exposed second adhesive layer 13 of the adhesive sheet 1 is bonded to one side of the surface substrate 22. Then, the other release liner 16a of the adhesive sheet 1 is peeled off, and the exposed first adhesive layer 12 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.

[0140] Here, if the first adhesive layer 12 and the second adhesive layer 13 of the adhesive sheet 1 are curable by active energy rays, it is preferable to cure the first adhesive layer 12 or the second adhesive layer 13 by irradiating one side (preferably the surface substrate 22 side) with active energy rays after laminating the surface substrate 22, the adhesive laminate 11, and the light-emitting substrate 21. This makes it easier to satisfy the aforementioned creep strain and gel fraction, and also results in superior adhesive strength.

[0141] Active energy rays refer to electromagnetic waves or charged particle beams that possess energy quanta, specifically including ultraviolet rays and electron beams. Among these, ultraviolet rays are particularly preferred because they are easy to handle.

[0142] 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.

[0143] As described above, after fabricating the laminate as unit panel 2, it is preferable to laser-cut the end faces of these laminates to form flat end faces and thus create unit panel 2. In these unit panel 2, since the aforementioned adhesive laminate 11 is used, the leakage of adhesive from the laser-cut end faces is suppressed, and lifting and peeling are less likely to occur at the interface between the first adhesive layer 12 and the light-emitting substrate 21, and at the interface between the second adhesive layer 13 and the surface substrate 22. As a result, in a tiling display made by joining multiple unit panels 2, there are almost no gaps between the unit panels, thereby achieving uniform brightness and high image quality.

[0144] Laser irradiation in laser cutting can be performed under general conditions. There are no particular restrictions on the type of laser used, but examples include gas lasers such as carbon dioxide (CO2) lasers, TEA-CO2 lasers, and excimer lasers; liquid lasers such as organic chelate compound lasers, inorganic lasers, and organic dye lasers; solid-state lasers such as YAG lasers, UV-YAG lasers, YVO4 lasers, and YLF lasers; and semiconductor lasers such as vertical cavity surface-emitting lasers and quantum dot lasers. Among these, gas lasers are preferred from the viewpoint of obtaining high laser output and excellent processability, and carbon dioxide (CO2) lasers or TEA-CO2 lasers are particularly preferred.

[0145] The wavelength of the irradiated laser light is preferably 0.1 to 1000 μm, more preferably 0.38 to 100 μm, particularly preferably 0.78 to 50 μm, even more preferably 1 to 25 μm, and most preferably 8 to 20 μm. The laser power density is generally 1.0 × 10⁻¹⁶. 3 ~1.0×10 10 W / cm2 and is preferably 1.0×10 4 ~1.0×10 8 W / cm 2 . Also, 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.

[0146] [[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 performed by a conventional method.

[0147] By connecting a plurality of unit panels 2 whose end faces are laser-cut and the bleeding of the adhesive is suppressed, the gap between the unit panels 2 is almost eliminated. As a result, in the tiling display according to the present embodiment, uniform luminance can be obtained and the image quality is high.

[0148] The embodiments described above are described to facilitate the understanding of the present invention and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0149] For example, either one of the release sheets 16a and 16b in the adhesive sheet 1 may be omitted. Also, the unit panel 2 may be provided with other desired layers.

[0150] 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]

[0151] 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.

[0152] [Example 1] 1. Preparation of (meth)acrylic acid ester polymers (Meth)acrylic acid ester polymer (A) 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 (A) was measured by the method described later, and the weight-average molecular weight (Mw) was found to be 500,000.

[0153] 2. Preparation of adhesive composition 100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth)acrylic acid ester polymer (A) 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 (B), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (EX1).

[0154] Table 1 shows the composition (solid content equivalent) of each adhesive when the total amount of the adhesive main component is 100 parts by mass (solid content equivalent). Details of the abbreviations etc. listed in Table 1 are as follows. Furthermore, regarding the colorant: PG1, Table 2 shows the optical properties of a solution obtained by diluting the colorant: PG1 listed in Table 1 10,000 times with ethyl acetate. The optical properties shown in Table 2 were calculated from the haze value (%) obtained using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000 for the above diluted solution. The haze value difference (points) is the difference between the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm, the average haze (%) is the average value of the haze value at a wavelength of 780 nm and the haze value at a wavelength of 380 nm, and the standard deviation of the haze value is the standard deviation of the haze value at each wavelength in 5 nm increments in the wavelength range of 380 nm to 780 nm. [Coloring agent] PG1: Carbon black-based black pigment (a pigment having the optical properties listed in Table 2 below) PG2: Pigment (Carbon Black, manufactured by Nikko Bigx Co., Ltd., product name "NSP-VH 805 BLACK")

[0155] 3. Manufacturing of adhesive sheets The coating solution of the adhesive composition (EX1) 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: 50 μm), which was used as the first laminate.

[0156] Similarly, the coating solution of the above-mentioned adhesive composition (EX1) was applied with a knife coater to the peeled surface of a lightly peelable release sheet R2, 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: 50 μm), which was used as the second laminate.

[0157] Subsequently, one side of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having easy-adhesion layers on both sides as a core material was bonded to the coated layer side of the first laminate, and the other side was bonded to the coated layer side of the second laminate. After curing for 7 days under conditions of 23°C and 50% RH, an adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was obtained.

[0158] The physical properties of the above-mentioned "Cosmoshine A4360" were as follows: • Tensile strength (breaking stress): MD: 230 MPa / TD: 275 MPa • Growth rate: MD: 140% / TD: 92% • Dimensional change rate due to heating: MD: 1.0% / TD: 0.3%

[0159] 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.

[0160] [Example 2] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C), 6.4 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9300-1CL") as an active energy ray curable component (D), and 0.6 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a photopolymerization initiator (E) were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (EX2).

[0161] Using the coating solution of the adhesive composition (EX2) obtained above, an active energy ray-curable adhesive sheet was obtained in the same manner as in Example 1, having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1.

[0162] [Example 3] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C), and 10 parts by mass of fine particles (light-diffusing fine particles; manufactured by Momentive Performance Materials Japan, product name "Tospar 145L", average particle size: 4.5 μm, refractive index: 1.43) made of silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) as a filler were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (EX3).

[0163] The coating solution of the adhesive composition (EX3) 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: 50 μm), which was used as the first laminate.

[0164] Subsequently, one side of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having easy-adhesion layers on both sides as a core material was bonded to the coated layer side of the first laminate, and the other side was bonded to the coated layer side of the second laminate prepared in Example 1. After curing for 7 days under conditions of 23°C and 50% RH, an adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was obtained.

[0165] [Example 4] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C), and 0.25 parts by mass of a carbon black-based black pigment (PG1; pigment having the optical properties described in Table 2) as a coloring agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (EX4).

[0166] The coating solution of the adhesive composition (EX4) 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: 50 μm), which was used as the first laminate.

[0167] Subsequently, one side of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having easy-adhesion layers on both sides as a core material was bonded to the coated layer side of the first laminate, and the other side was bonded to the coated layer side of the second laminate prepared in Example 1. After curing for 7 days under conditions of 23°C and 50% RH, an adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was obtained.

[0168] [Example 5] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C), and 0.62 parts by mass of a pigment (PG2; carbon black, manufactured by Nikko Bix Co., Ltd., product name "NSP-VH 805 BLACK") as a coloring agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (EX5).

[0169] The coating solution of the adhesive composition (EX5) 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: 50 μm), which was used as the first laminate.

[0170] Subsequently, one side of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having easy-adhesion layers on both sides as a core material was bonded to the coated layer side of the first laminate, and the other side was bonded to the coated layer side of the second laminate prepared in Example 1. After curing for 7 days under conditions of 23°C and 50% RH, an adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was obtained.

[0171] [Example 6] The coating solution of the adhesive composition (EX3) obtained in Example 3 was applied with a knife coater to the peeled surface of a light-peel type release sheet R2, 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: 50 μm), which was used as the second laminate.

[0172] A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness: 100 μm) having easy-adhesion layers on both sides as a core material was bonded to one side with the coated layer side of the first laminate prepared in Example 4, and to the other side with the coated layer side of the second laminate. After curing for 7 days under conditions of 23°C and 50% RH, an adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was obtained.

[0173] [Example 7] An adhesive sheet was manufactured in the same manner as in Example 1, except that a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "Lumirror #25-F65", thickness: 25 μm) was used as the core material, and the thickness of the first adhesive layer was 87 μm and the thickness of the second adhesive layer was 88 μm. That is, an adhesive sheet was manufactured having a layer structure of release sheet R2 / second adhesive layer (88 μm) / core material (25 μm) / first adhesive layer (87 μm) / release sheet R1.

[0174] [Comparative Example 1] A coating solution of the adhesive composition (EX1) obtained in the same manner as in Example 1 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.

[0175] Similarly, the coating solution of the above-mentioned adhesive composition (EX1) was applied with a knife coater to the peeled surface of a lightly peelable release sheet R2, 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 second laminate.

[0176] 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.

[0177] [Comparative Example 2] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 0.02 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (CE2).

[0178] An adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was manufactured in the same manner as in Example 1, except that the coating solution of the adhesive composition (EX1) was used instead of the coating solution of the adhesive composition (CE2).

[0179] [Comparative Example 3] 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the same manner as in Example 1, 1.5 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name "Takenate D-101E") as a crosslinking agent (B), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent (C) were mixed, stirred thoroughly, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition (CE3).

[0180] An adhesive sheet having a layer structure of release sheet R2 / second adhesive layer (50 μm) / core material (100 μm) / first adhesive layer (50 μm) / release sheet R1 was manufactured in the same manner as in Example 1, except that the coating solution of the adhesive composition (EX1) was used instead of the coating solution of the adhesive composition (CE3).

[0181] 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℃

[0182] [Test Example 1] (Measurement of gel fraction) For Examples 1-7 and Comparative Examples 2-3, the first and second laminates obtained during the manufacturing of the adhesive sheets were cured for 7 days under conditions of 23°C and 50% RH. Then, the first and second laminates were cut to a size of 80 mm x 80 mm, and the adhesive layers (first adhesive layer and second adhesive layer) were 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. For Comparative Example 1, the manufactured adhesive sheet was cut to a size of 80 mm x 80 mm, and the mass of the adhesive layer (single-layer adhesive layer) was calculated in the same manner as above. This mass is denoted as M1.

[0183] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. The adhesive was then 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 3.

[0184] Furthermore, for the adhesive sheet of Example 2, the gel fraction (after UV) was also measured after irradiation of the adhesive layer with active energy rays (ultraviolet light; UV) through the release sheet R2. The irradiation conditions for the active energy rays are as follows.

[0185] <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.

[0186] [Test Example 2] (Measurement of creep strain) For the adhesive sheets of Examples 1-7 and Comparative Examples 2-3, cylindrical bodies with a diameter of 8 mm were punched out from the adhesive layer (thickness: 200 μm) consisting of a first adhesive layer, a core material, and a second adhesive layer, as well as from the adhesive layer (thickness: 200 μm) of the adhesive sheet of Comparative Example 1, and these were used as samples. For the adhesive sheet of Example 2, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0187] 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 3. Measurement frequency: 1Hz Measurement temperature: 23℃

[0188] [Test Example 3] (Tensile Test) Samples (MD and TD) measuring 10 mm wide x 75 mm long were cut from the adhesive laminates (thickness: 200 μm) consisting of the first adhesive layer, core material, and second adhesive layer of the adhesive sheets of Examples 1-7 and Comparative Examples 2-3, as well as from the adhesive layer (thickness: 200 μm) of the adhesive sheet of Comparative Example 1. For the adhesive sheet of Example 2, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0189] 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 3.

[0190] 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 3.

[0191] [Test Example 4] (Measurement of Adhesion) The release sheet R2 was peeled off from the adhesive sheets produced in Examples 1-7 and Comparative Examples 2-3. The second adhesive layer of the exposed adhesive laminate was bonded to the easy-adhesion layer of a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., product name "Cosmoshine PET A4360", thickness: 100 μm) having an easy-adhesion layer, thereby obtaining a laminate consisting of release sheet R1 / first adhesive layer / core material / second adhesive layer / PET film. The obtained laminate was cut to a width of 25 mm and a length of 100 mm.

[0192] Under conditions of 23°C and 50%RH, the release sheet R1 was peeled off the laminate, and the first adhesive layer of the exposed adhesive laminate was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). This was then subjected to pressure of 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) of the first adhesive layer 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 other than those described here were performed in accordance with JIS Z0237:2022. The results are shown in Table 3.

[0193] The adhesive strength (before UV exposure; N / 25mm) of the second adhesive layer of the adhesive sheets produced in Examples 1-7 and Comparative Examples 2-3 was measured in the same manner as described above. The results are shown in Table 3.

[0194] Furthermore, the release sheet R2 was peeled off from the adhesive sheet of Comparative Example 1, 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.

[0195] Under conditions of 23°C and 50%RH, the release sheet R1 was peeled off from the laminate, and the exposed adhesive layer was attached to soda-lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). The sheet was then pressurized at 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) of this sample was measured in the same manner as above. The results are shown in Table 3.

[0196] For the adhesive sheet of Example 2, 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 3.

[0197] [Test Example 5] (Measurement of total light transmittance) The adhesive laminates and 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 3.

[0198] Furthermore, for the adhesive sheet of Example 2, 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.

[0199] [Test Example 6] (Measurement of haze value) The adhesive laminates and 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 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 3.

[0200] Furthermore, for the adhesive sheet of Example 2, 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 those for Test Example 1.

[0201] [Test Example 7] (Measurement of dimensional change rate) Adhesive laminates (thickness: 200 μm) consisting of a first adhesive layer, core material, and second adhesive layer were cut from the adhesive sheets of Examples 1-7 and Comparative Examples 2-3, as well as from the adhesive layer (thickness: 200 μm) of the adhesive sheet of Comparative Example 1, with a width of 5 mm and a length of 30 mm (MD / TD). For the adhesive sheet of Example 2, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0202] 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 3. Note that a negative value indicates that the sample contracted, and a positive value indicates that it expanded.

[0203] [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 2, the adhesive layer was cured with active energy rays in the same manner as in Test Example 1.

[0204] 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

[0205] 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 3. ○...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.

[0206] [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 3. ◎...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.

[0207] [Table 1]

[0208] [Table 2]

[0209] [Table 3]

[0210] As can be seen from Table 3, the adhesive sheets manufactured in the examples exhibited excellent laser-cutting properties and adhesion to the substrate. [Industrial applicability]

[0211] 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]

[0212] 1…Adhesive sheet 11…Adhesive laminate 12…First adhesive layer 12S... Adhesive surface of the first adhesive layer 13…Second adhesive layer 13S... Adhesive surface of the second adhesive layer 14…Core material 16a, 16b… 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, A first adhesive layer, A second adhesive layer, A core material provided between the first adhesive layer and the second adhesive layer It is equipped with, The adhesive laminate comprising the first adhesive layer, the core material, and the second adhesive layer is subjected to a torsional shear test in accordance with JIS K7244-6, where a pressure of 10 kPa is applied for 600 seconds at a temperature of 23°C and a frequency of 1 Hz, and the resulting strain is 120% or less. The adhesive strength of the first adhesive layer and the second adhesive layer to the soda-lime glass is 5 N / 25 mm or more, respectively. An adhesive sheet characterized by the following features.

2. An adhesive sheet used in the manufacture of unit panels that make up a tiling display, A first adhesive layer, A second adhesive layer, A core material provided between the first adhesive layer and the second adhesive layer It is equipped with, The gel fractions of the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are 30% or more and 99% or less, respectively. The adhesive strength of the first adhesive layer and the second adhesive layer to the soda-lime glass is 5 N / 25 mm or more, respectively. An adhesive sheet characterized by the following features.

3. The adhesive sheet according to claim 1, characterized in that the gel fractions of the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are 30% or more and 99% or less, respectively.

4. The adhesive sheet according to claim 1 or 2, characterized in that the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are each acrylic adhesives.

5. The thicknesses of the first adhesive layer and the second adhesive layer are 1 μm or more and 100 μm or less, respectively. The thickness of the core material is 1 μm or more and 300 μm or less. The adhesive sheet according to feature 1 or 2.

6. The adhesive sheet according to claim 1 or 2, characterized in that the core material is made of a plastic film.

7. A release sheet protecting the adhesive surface of the first adhesive layer, A release sheet that protects the adhesive surface of the second adhesive layer and The adhesive sheet according to claim 1 or 2, characterized by comprising the above.

8. A unit panel that constitutes a tiling display, The adhesive sheet according to claim 1 or 2 comprises an adhesive laminate comprising the first adhesive layer, the core material, and the second adhesive layer. 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 laminate. 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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