Sealing sheet and display

Abstract

Provided are: a sealing sheet which has excellent light resistance and excellent embeddability even when applied to a display in which a plurality of light-emitting elements are used as light sources; and a display having a sealing layer. The problem is solved by a sealing sheet comprising a resin composition layer containing a resin (A) having a glass transition temperature (Tg) of-30 DEG C to 40 DEG C and a weight average molecular weight (Mw) of 10,000 to 1,000,000 and an embedding modifier (B) containing a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2), the thickness Ta of the resin composition layer is 1 [mu] m to 100 [mu] m, and the sealing sheet is used for a display using a plurality of light-emitting elements as light sources.

Description

Technical Field

[0001] The present disclosure relates to a sealing sheet, and more particularly, to a sealing sheet including a resin composition layer for sealing a plurality of light-emitting elements used in various articles represented by, for example, electronic devices or displays, and a display having a sealing layer including the resin composition layer. Background Art

[0002] In recent years, with the aim of further high performance, the development of various light-emitting elements has been actively carried out for displays. Specifically, various display specifications such as backlight displays using liquid crystals or quantum dots, displays using self-luminous elements such as mini / micro light-emitting diodes (LEDs) or organic electroluminescence (EL), plasma displays, and electrophoretic displays have been studied, and extensive applications have been studied in the range from large display uses such as self-signage or televisions to small-size uses such as tablet computers, personal computers, smartphones, and wearable devices. In particular, the development of displays using LEDs has been progressing, and a thermosetting resin composition for sealing LED elements is described in Patent Document 1. As a next-generation display technology, the micro-LED display is the most promising.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-12051 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Patent Document 1 describes a sheet-like resin composition for sealing a photo-semiconductor element with excellent heat resistance. However, in recent years, in LED elements with progress in miniaturization, the interval between LED elements has become narrower, and it is difficult for the sheet-like resin composition described in Patent Document 1 to follow the micro-sized LED elements to fill the empty areas (embedding property). When there are empty areas between the LED elements and the sealing resin composition, light is refracted and the clarity of the display deteriorates.

[0008] In addition, when using a display outdoors, high light resistance is required. However, existing sealing sheets turn yellow over time due to exposure to sunlight, and thus there is a problem that the image displayed on the display turns yellow.

[0009] In order to produce a display with excellent clarity or less yellowing over time, a sealing sheet with excellent embedding property and light resistance is required.

[0010] In view of the above problems, the present disclosure aims to provide a sealing sheet and a display having a resin composition layer, which have excellent embedding property and light resistance even when applied to a display using various light-emitting elements such as organic ELs as well as LED elements as light sources.

[0011] In addition, as a further problem, from the viewpoint of simplifying the manufacturing process of a micro-LED display, a sealing sheet with excellent adhesion or zipping property to a substrate is provided.

[0012] Technical means for solving the problems

[0013] The inventors of the present invention made intensive studies and found that the above problems can be solved by the following sealing sheet, thereby completing the present invention of [1] to [8] below.

[0014] [1]: A sealing sheet for sealing a light-emitting element used in a display using a plurality of light-emitting elements as light sources, the sealing sheet including a resin composition layer containing a resin (A) and an embedding property improver (B), the glass transition temperature (Tg) of the resin (A) being -30°C to 40°C and the weight average molecular weight (Mw) being 10,000 to 1,000,000, the embedding property improver (B) containing a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2), and the thickness Ta of the resin composition layer being 1 μm to 100 μm.

[0015] [2]: The sealing sheet according to [1], wherein the resin (A) is a (meth)acrylic resin (a),

[0016] The (meth)acrylic resin (a) is a copolymer containing a structural unit derived from an acrylic alkyl ester (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 12 carbon atoms and a structural unit derived from a methacrylic alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms.

[0017] [3]: The sealing sheet according to [2], wherein the (meth)acrylic resin (a) further contains a structural unit derived from (meth)acrylic acid (a3).

[0018] [4]: The sealing sheet according to any one of [1] to [3], containing 76% by mass to 99.9% by mass of the resin (A) relative to the total mass of the resin composition layer.

[0019] [5]: The sealing sheet according to any one of [1] to [4], wherein the content rate of the embedding improver (B) is 0.1% by mass to 15% by mass with respect to the total mass of the resin composition layer.

[0020] [6]: The sealing sheet according to any one of [1] to [5], wherein the mass ratio B1:B2 of the phosphorus-containing compound (B1) to the phenolic hydroxyl group-containing compound (B2) in the embedding improver (B) is 0.1:1 to 10:1.

[0021] [7]: The sealing sheet according to any one of [1] to [6], wherein the loss tangent (tanδ40) at 40°C obtained by dynamic viscoelasticity measurement in a tensile mode at a frequency of 10 Hz of the resin composition layer is 0.8 to 2.0.

[0022] [8]: A display having a sealing layer including a resin composition layer of the sealing sheet according to [7].

[0023] [Effects of the Invention]

[0024] According to the present disclosure, it is possible to provide a sealing sheet having excellent embedding property and light resistance even when applied to a display using a plurality of light-emitting elements as a light source. In addition, according to the present disclosure, in addition to the sealing sheet, it is also possible to provide a sealing sheet having excellent embedding property, light resistance, adhesion to a substrate, or tear resistance even when applied to a display using a micro-LED element as a light source. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0025] Figure 1A It is a schematic cross-sectional view showing an example of the laminated structure of the sealing sheet.

[0026] Figure 1B It is a schematic cross-sectional view showing another example of the laminated structure of the sealing sheet.

[0027] Figure 1C It is a schematic cross-sectional view showing another example of the laminated structure of the sealing sheet.

[0028] Figure 2 It is a schematic cross-sectional view showing a process of sealing a light-emitting element on a substrate having a plurality of light-emitting elements.

[0029] Figure 3 It is a cross-sectional view showing an example of a test substrate imitating a substrate of a micro-LED. [DETAILED DESCRIPTION]

[0030] Hereinafter, the present disclosure will be described in detail. In addition, the embodiments described below illustrate an example of the present disclosure. The present disclosure is not limited to the following embodiments, and also includes modified examples implemented within the scope of not changing the gist of the present disclosure.

[0031] In this specification, a numerical range specified using "~" includes the numerical values described before and after "~" as a range of lower limit value and upper limit value. (Meth)acrylic acid means acrylic acid and methacrylic acid. In addition, regarding various components appearing in this specification, unless otherwise noted, each can be used independently alone, or two or more can be used in combination.

[0032] In the present disclosure, by having the weight average molecular weight (Mw) of resin (A) be 10,000 or more and 1,000,000 or less, the glass transition temperature (Tg) of resin (A) be -30°C to 40°C, the embedding property improver (B) contain a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2), and the thickness Ta of the resin composition layer be 1 μm to 100 μm, light resistance and embedding property can be improved. Furthermore, adhesion and tearability can also be improved. Regarding the above effects, the speculation of the present inventors is described in the following items.

[0033] [Form of the sealing sheet]

[0034] The sealing sheet of the present disclosure at least includes a resin composition layer. Regarding the sealing sheet, as Figure 1A shown, a structure in which a resin composition layer 2 and a release liner 4 are laminated can be exemplified. In addition, as Figure 1B shown, it can also be a structure in which a resin composition layer 2 and a substrate 3 are laminated. The lamination structure of the resin composition layer and the substrate or / and the release liner is not particularly limited.

[0035] Examples of the release liner include: polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; plastic films such as polyolefin films like polypropylene or polyethylene; or plastic films provided with a release layer by coating a release agent such as silicone resin on a plastic sheet. Regarding the thickness of the release liner, there is no particular limitation, and it is about 10 μm to 200 μm.

[0036] As the base material, there is no particular limitation, and examples thereof include: plastic films, or various optical films such as anti-reflective (AR) films, polarizing plates, and retardation plates. As the plastic film, examples include: polyvinyl chloride films, polyethylene films, polyethylene terephthalate (PET) films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, cycloolefin films, etc. The thickness of the base material is not particularly limited, and is preferably in the range of 10 μm to 2000 μm. In addition, the sealing sheet of the present disclosure is preferably a three-layer structure of base material / resin composition layer / release liner.

[0037] As Figure 1C shown, the sealing sheet of the present disclosure is particularly preferably a three-layer structure of a first release liner 4a / resin composition layer 2 / a second release liner 4b.

[0038] The first release liner and the second release liner can be arbitrarily selected, and the same release liner can also be used. From the viewpoint of processing, it is preferred that the first release liner is a light release liner and the second release liner is a heavy release liner. The thickness Tl of the light release liner is preferably in the range of 10 μm to 150 μm, the thickness Th of the heavy release liner is preferably in the range of 25 μm to 200 μm, and it is preferably satisfied that Tl < Th. In addition, when the sealing sheet is in a roll form, it is preferred to dispose the light release liner on the outside of the roll.

[0039] The release forces of the first release liner and the second release liner can be adjusted by the release treatment of the attachment surface of each release liner to the resin composition layer. For example, it can be adjusted by the type of release agent, the coating amount of the release agent, and the surface roughness of the release layer. When it is desired to reduce the value of the release force, treatments such as increasing the surface roughness and increasing the coating amount of the release agent are effective. When it is desired to increase the value of the release force, it is only necessary to make the opposite adjustment. In the case of adopting Figure 1C the three-layer structure shown, it is preferred to use a manufacturing method in which the first release liner 4a is attached after the resin composition layer 2 is formed on the second release liner 4b.

[0040] After manufacturing the sealing sheet or simultaneously with the manufacturing of the sealing sheet, the sealing sheet is wound around a core in a roll shape, whereby a roll of the sealing sheet can be obtained. The winding length can be designed according to the use. From the viewpoint of improving productivity, it is preferably 50 m or more, and more preferably 100 m or more. From the viewpoint of manufacturing yield, the winding length is preferably set to 10000 m or less.

[0041] The sealing sheet of the present disclosure is preferably used for sealing light-emitting elements used in a display using a plurality of light-emitting elements as light sources. Examples of displays using a plurality of light-emitting elements as light sources include displays that require high quality, such as organic EL display panels and micro-LED display panels.

[0042] The resin composition layer constituting the sealing sheet is preferably in direct contact with and laminated on the adherend. The adherend to be in contact with is not particularly limited, and is preferably acrylic, urethane, polycarbonate, epoxy, polyimide, glass, paper, cloth, aluminum, ceramic, or polyethylene terephthalate, etc. Further, the adherend is more preferably a substrate having an electrode portion containing a metal, or a substrate having a plurality of light-emitting element portions such as a backlight module, an LED, or an organic EL. In addition, the substrate having a plurality of light-emitting element portions may further have a light-shielding layer between the light-emitting element portions.

[0043] Since the resin composition layer constituting the sealing sheet has high followability to uneven surfaces, it is suitable for use in filling between light-emitting elements following a plurality of light-emitting elements. By filling the resin composition layer between the light-emitting elements, a sealing layer containing the resin composition layer is formed. The sealing layer has the function of fixing adjacent light-emitting elements and preventing detachment or displacement. In particular, the resin composition layer of the sealing sheet of the present disclosure can follow micro-sized light-emitting elements, so a micro-LED is more suitable as the light-emitting element, and it is more preferable to use the resin composition layer as the sealing layer of a micro-LED display panel.

[0044] A micro-LED refers to a fine LED chip of 50 μm or 100 μm or less. By mounting a plurality of the micro-LEDs (chips) on a substrate formed with wirings or circuits, a display using a plurality of light-emitting elements as light sources is formed. A micro-LED is formed of an LED element such as GaAs, GaP, AlGaInP, or InGaN, a sealing resin for sealing it, a packaging substrate, electrodes, etc., and the operating temperature is 25°C to 60°C. Hereinafter, Figure 2 An example of the process for forming the sealing layer will be described.

[0045] Process (a): Placement process of the sealing sheet

[0046] As Figure 2 As shown in an example in (a), the resin composition layer of the sealing sheet is placed on a substrate having a plurality of light-emitting elements so as to directly cover the light-emitting elements. Further, when the sealing sheet has a first release liner and a second release liner, after peeling off the first release liner to expose the resin composition layer, it is placed as described above. The second release liner can be peeled off immediately after placement, or can be peeled off after the pressing process shown below.

[0047] In this specification, the plurality of light-emitting elements is not particularly limited as long as there are two or more light-emitting elements. In the display application, the number of light-emitting elements used is determined by the display size or the number of pixels.

[0048] In addition, the emission color of the light-emitting element is not particularly limited, and an organic EL light-emitting element or an LED light-emitting element can be applied. Examples of the emission color include red, green, and blue.

[0049] Regarding the size of the light-emitting element, it is preferably 100 μm or less in thickness and 40000 μm in area when viewed from above. 2 Hereinafter, it is more preferably 50 μm or less in thickness and 10000 μm in area when viewed from above. 2 Hereinafter, it is further preferably 20 μm or less in thickness and 2500 μm in area when viewed from above. 2 Hereinafter.

[0050] The interval between the light-emitting elements placed on the substrate is, for example, 10 μm to 5000 μm. When the red, green, and blue light-emitting elements are set as a group and placed on the substrate as one pixel, the interval between the pixels is, for example, 10 μm to 2000 μm, preferably 20 μm to 1800 μm, and more preferably 500 μm to 1500 μm. The interval between the light-emitting elements in one pixel is, for example, 10 μm to 200 μm, preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm.

[0051] Process (b): Pressing process

[0052] As Figure 2 (b) shows, by pressing, the resin composition layer flows and fills around or between the plurality of light-emitting elements on the substrate. The resin composition layer filled around or between the plurality of light-emitting elements becomes a sealing layer. The pressing method is not particularly limited, and hot pressing or vacuum pressing is preferred. From the viewpoint of the filling property of the resin composition layer, the temperature during pressing is preferably 20°C to 200°C, more preferably 30°C to 150°C, further preferably 40°C to 130°C, and particularly preferably 60°C to 110°C.

[0053] In order to improve the adhesion to the light-emitting element or the adherend, heat aging may be further performed after pressing. The heating temperature is preferably 40°C to 250°C, more preferably 80°C to 220°C, and further preferably 100°C to 190°C. The heating time is preferably 30 minutes to 300 minutes, more preferably 60 minutes to 240 minutes, and further preferably 90 minutes to 180 minutes. By setting the heating temperature and heating time as described above, the residual stress of the resin composition layer can be removed and the adhesion surface can be smoothed. Heat aging can also be performed after the following process (c).

[0054] Step (c): Etching step

[0055] In step (c), etching is performed to remove or thin the sealing layer on the light-emitting element. By removing the sealing layer, the luminance of the light-emitting element is increased, ensuring visibility during light emission. The thickness of the sealing layer after etching is preferably on the same order as the thickness of the light-emitting element as shown in Figure 2 (c-1), or below the thickness of the light-emitting element as shown in Figure 2 (c-2). In addition, even if the sealing layer is not completely removed from the light-emitting element, it suffices as long as it is substantially removed, and it may be in a state where some thin film remains. Further, step (c) may be omitted when visibility can be ensured.

[0056] The etching method is not particularly limited, and preferred examples include wet etching methods such as chemical polishing using a chemical agent, or dry etching methods such as physical polishing using an abrasive material, laser etching, plasma etching using argon plasma or oxygen plasma, and ion beam etching. From the viewpoint of reducing surface irregularities, it is preferable to use a combination of a wet etching method and a dry etching method.

[0057] Alternatively, it may be physical etching such as plasma treatment. As etching conditions, for example, as long as a mixed gas of CF 4 / O 2 / N 2 is used in an anisotropic plasma apparatus, dry etching may be performed under conditions of a power of 1500 W to 3000 W and 180 seconds to 600 seconds. At this time, as the gas supply amount of CF 4 , for example, it suffices as long as it is 50 sccm to 100 sccm, and as the gas supply amount of O 2 , for example, it suffices as long as it is set to 500 sccm to 1000 sccm, and as the gas supply amount of N 2 , for example, it suffices as long as it is set to 50 sccm to 100 sccm.

[0058] Through the above-described steps (a) to (c), a sealing layer can be formed from the resin composition layer. Next, preferred examples will be given to describe in detail the constituent components of the sealing sheet of the present disclosure.

[0059] [Resin composition layer]

[0060] The resin composition layer preferably contains a resin (A) and an embedding property improver (B) and further contains a crosslinking agent, and may also contain other components.

[0061] In the present disclosure, the resin (A) refers to a substance having a function of bonding and fixing objects to each other as an adhesive. As specific examples, there may be mentioned functions of bonding and fixing to a substrate having a light-emitting element or a plurality of light-emitting elements.

[0062] The loss tangent (tanδ40) at 40°C obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure is preferably 0.8 to 2.2, more preferably 1.0 to 2.0, and still more preferably 1.5 to 1.9. By setting tanδ40 to 0.8 to 2.2, the diffusibility of the pressure applied to the resin composition layer in the pressing process becomes good, and the embedding property, the adhesion to the adherend, and the tearing property are improved. When tanδ40 is less than 0.8, the diffusibility of the resin composition layer in the pressing process is too high, so the resin composition layer easily flows, and the end of the sealing layer after the pressing process becomes thin. When tanδ40 is higher than 2.2, the diffusibility of the resin composition layer in the pressing process is too low, so the fluidity of the resin composition layer deteriorates, and an empty region is formed between the adherend and the sealing layer.

[0063] The loss tangent (tanδ40) is the ratio of the loss elastic modulus to the storage elastic modulus obtained by dynamic viscoelasticity measurement in the tensile mode at a frequency of 10 Hz and from -50°C to 150°C.

[0064] tanδ40 can be adjusted by the type or composition of the resin (A). When the resin (A) contains a (meth)acrylic resin (a), tanδ40 can be increased by increasing the content of the alkyl methacrylate (a2). When it is desired to decrease tanδ40, the opposite adjustment can be made.

[0065] In addition, the peak temperature (tanδ peak temperature) of the loss tangent (tanδ) obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure refers to the temperature at which the peak of tanδ is the largest. When there are two or more peaks, it represents the peak temperature on the lowest temperature side. The tanδ peak temperature is preferably between 0°C and 60°C, more preferably between 15°C and 55°C, and still more preferably between 35°C and 45°C. By having the tanδ peak temperature between 0°C and 60°C, the molecular chains of the resin composition layer and the network structure of the embedding property improver (B) can be stabilized through the heat aging process, and the residual stress of the resin can be sufficiently removed, so the adhesion to the adherend is improved.

[0066] In addition, the tanδ peak temperature of the present disclosure can be adjusted by the type or composition of the resin (A), the type or addition amount of the crosslinking agent, the type or addition amount of the embedding property improver (B), and the addition amount of other components. When the resin (A) contains the (meth)acrylic resin (a), by increasing the content of the monomer having a high glass transition temperature (Tg) of the homopolymer, the tanδ peak temperature can be increased. When it is desired to decrease the tanδ peak temperature, the adjustment can be made conversely. The glass transition temperature (Tg) of the homopolymer in the present disclosure can use the values described in "Polymer Handbook, 1999, Fourth Edition (POLYMER HANDBOOK, 1999, FOURTH EDITION)". Specifically, as the monomers having a glass transition temperature (Tg) of the homopolymer of 0°C or higher, methyl acrylate, cyclohexyl acrylate, methyl methacrylate, and butyl methacrylate can be mentioned. As the monomers having a glass transition temperature (Tg) of the homopolymer of less than 0°C, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and 2-ethylhexyl methacrylate can be mentioned.

[0067] In addition, the peak intensity (tanδ peak intensity) in the range of -50°C to 80°C of the loss tangent (tanδ) obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure refers to the value of the loss tangent (tanδ) when the peak of tanδ is the largest. When there are two or more peaks, it represents the peak intensity on the lowest temperature side. The tanδ peak intensity is preferably 0.8 to 2.2, more preferably 1.0 to 2.0, and still more preferably 1.5 to 1.9. By setting the tanδ peak intensity to 0.8 to 2.2, the absorbability of the pressure applied to the resin composition layer in the pressing process becomes good, and while forming a uniform sealing layer, it follows the light-emitting element and the embedding property is improved.

[0068] In addition, the tanδ peak intensity of the present disclosure can be adjusted by the type or composition of the resin (A). When the resin (A) contains the (meth)acrylic resin (a), by increasing the content of the alkyl acrylate (a1), the tanδ peak intensity can be decreased. When it is desired to increase the tanδ peak intensity, the adjustment can be made conversely.

[0069] The dynamic viscoelasticity and the loss tangent (tanδ) in the present disclosure are measured by the methods described in the following examples. In addition, when the resin composition layer contains a crosslinking agent, the crosslinking reaction based on heating is in an unfinished state during the measurement.

[0070] Regarding the viewpoints of embedability and tearability, the thickness Ta of the resin composition layer is 1 μm to 100 μm, preferably 3 μm to 50 μm, and more preferably 5 μm to 35 μm. By setting the thickness Ta of the resin composition layer to 1 μm or more, the stress when peeling off the release liner is efficiently dispersed, and sufficient tearability is exhibited. In addition, the pressure in the pressing process is diffused within the resin composition layer, and sufficient embedability is exhibited. When the thickness Ta of the resin composition layer is 100 μm or less, the pressure loss absorbed by the resin composition layer with respect to the pressure applied in the pressing process is small, and the resin composition layer flows sufficiently, so excellent embedability is exhibited. In addition, when peeling off the release liner, the stress applied to the resin composition layer is not likely to shift, so excellent tearability is exhibited.

[0071] When the thickness Ta of the resin composition layer is less than 1 μm, when the resin composition layer flows in the pressing process, the pressure in the resin composition layer is not completely dispersed and is likely to shift, resulting in poor embedability. In addition, the stress applied to the resin composition layer when peeling off the release liner is not completely dispersed, resulting in poor tearability. When the thickness Ta of the resin composition layer is greater than 100 μm, when the resin composition layer flows in the pressing process, the end portion of the resin composition layer is likely to flow, the thickness of the resin composition layer becomes uneven, and a difference in the applied pressure is generated, thereby resulting in poor embedability. In addition, since cohesive failure is likely to occur within the resin composition layer, the tearability becomes poor. The resin composition layer can be either a single layer or a laminate of two or more layers. The thickness Ta in the present disclosure is measured by the method described in the examples below.

[0072] [Method for forming resin composition layer]

[0073] The method for forming the resin composition layer is not particularly limited. As a suitable example, a method of forming a resin composition layer by coating a resin composition obtained by adding an arbitrary solvent to the components constituting the resin composition layer can be cited. The purpose of adding the solvent is to adjust the viscosity level suitable for coating.

[0074] Known coating machines or methods such as a bevel-edge wheel coater, a die coater, a roll coater, a die lip coater, a reverse coater, an intaglio coater, a bar coater, a curtain coater, dip coating, spin coating, screen printing, and casting can be used for coating. The solvent contained in the resin composition can be removed by a drying process after coating.

[0075] As a preferred embodiment, the resin composition can be coated on a support such as a release liner or a substrate, and then the coated film is heated and dried using a hot air oven, an infrared heater, etc., thereby forming a resin composition layer on one surface of the support. Further, in order to increase the crosslinking density of the resin composition layer, for example, it is preferable to perform an aging treatment such as standing at a specific temperature condition, or irradiate ultraviolet rays (UV), etc.

[0076] [Resin composition]

[0077] The resin composition can be obtained by stirring and mixing a solvent, a resin (A), and an embedding property improver (B). Any solvent is used for the purpose of adjusting the viscosity and other processing appropriateness when mixing the resin (A) and the embedding property improver (B), so solvents such as ester-based, ether ester-based, ether-based, alcohol-based, and aromatic-based solvents that can be compatible with the resin (A) can be suitably used. Specifically, acetone, 2-butanone, ethyl acetate, cyclohexanone, toluene, xylene, isopropyl alcohol, N-methyl-2-pyrrolidone, etc. can be cited as suitable examples. Stirring can be carried out using known stirring devices, preferably a disperser, a mixer, an oscillator, a homogenizer, etc.

[0078] In order to obtain the resin composition, the following manufacturing process can be adopted: First, a mixture is prepared by mixing the embedding property improver (B) with the resin (A) or any solvent, and second, a two-stage or more manufacturing process of adding the resin (A), a crosslinking agent, and other components as needed.

[0079] [Resin (A)]

[0080] As the resin (A), any one of a thermosetting resin, a photocurable resin, and a thermoplastic resin can be used, and a single kind can be used, or two or more kinds can be used in combination. From the viewpoint of embedding property, it is preferably a thermosetting resin containing at least one or more kinds. The thermosetting resin is a resin having a plurality of functional groups that can be utilized in crosslinking reactions based on heating, and may also have functional groups capable of self-crosslinking. The resin may also contain a thermosetting monomer, but in this embodiment, from the viewpoint of film strength, it is preferable to use a thermosetting resin having a weight average molecular weight (Mw) of 10,000 or more.

[0081] Preferable examples of the thermosetting resin include: (meth)acrylic resin (a), maleic resin, polybutadiene resin, polyester resin, condensation type polyester resin, addition type polyester resin, melamine resin, urethane resins such as polyurethane resin or polyurethane urea resin, epoxy resin, polycarbonate resin, oxetane resin, phenoxy resin, polyimide resin, polyamideimide resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluororesin, etc. From the viewpoint of embeddability, it is preferably at least one of (meth)acrylic resin (a), epoxy resin, urethane resin, polycarbonate resin, and polyamide resin. Further, from the viewpoints of adhesion and peelability to the adherend, it is more preferably (meth)acrylic resin (a). In addition, from the viewpoint of light resistance, it is particularly preferably (meth)acrylic resin (a) with high transparency and low oxidation degradation tendency.

[0082] The functional group of the thermosetting resin can be appropriately selected according to the combination with the crosslinking agent described later. For example, it includes: hydroxyl group, carboxyl group, amino group, epoxy group, oxetanyl group, oxazolinyl group, oxazinyl group, aziridinyl group, mercapto group, isocyanate group, blocked isocyanate group, silanol group, etc. From the viewpoint of compatibility with the embedding improver (B), carboxyl group, hydroxyl group, and epoxy group are preferred. When having a carboxyl group, the acid value of the thermosetting resin is preferably 1 mgKOH / g to 50 mgKOH / g, more preferably 3 mgKOH / g to 30 mgKOH / g, and further preferably 5 mgKOH / g to 20 mgKOH / g.

[0083] By setting the acid value of the thermosetting resin to 1 mgKOH / g or more, while optimizing the crosslinking density with the crosslinking agent, the intermolecular force with the adherend is well maintained, and the light resistance, adhesion, and peelability become good. By setting the acid value of the thermosetting resin to 50 mgKOH / g or less, the intermolecular force with the adherend can be well maintained, and the residual amount of the carboxyl group that exacerbates the yellowing of the resin after the crosslinking reaction can be appropriately adjusted, so the light resistance, adhesion, and peelability become good. The acid value in the present disclosure is measured by the method described in the following examples.

[0084] In the present disclosure, urethane resin refers to the general term of compounds containing two or more urethane bonds in one molecule. The urethane resin can be obtained by reacting polyisocyanate with polyol.

[0085] The polyisocyanate may be any substance having two or more isocyanate groups in one molecule. In terms of the compatibility with the embedding improver (B), diisocyanate or triisocyanate is preferred, and diisocyanate is more preferred. As the diisocyanate, it can be appropriately selected and used from known aliphatic diisocyanates such as hexamethylene diisocyanate, or known aromatic diisocyanates such as benzene-1,3-diisocyanate. In addition, an isocyanate group-terminated prepolymer obtained by reacting a polyol with an excess of polyisocyanate can also be used as an intermediate of the urethane resin.

[0086] The polyol may be any substance having two or more hydroxyl groups in one molecule. In terms of the compatibility with the embedding improver (B), diol or triol is preferred, and diol is more preferred. As the diol, it can be appropriately selected and used from known aliphatic diols such as ethylene glycol, or known aromatic diols such as benzene diol. In addition, prepolymers such as polyether polyol, polyester polyol, and polycarbonate polyol can also be used.

[0087] The urethane resin may further be a polyurethane urea resin having a urea bond. The polyurethane urea resin can be synthesized, for example, by reacting a polyamine with a urethane resin having an isocyanate group at the terminal.

[0088] The polyamine may be any substance having two or more amino groups in one molecule. In terms of the compatibility with the embedding improver (B), diamine or triamine is preferred, and diamine is more preferred. As the diamine, it can be appropriately selected and used from known aliphatic diamines such as ethylenediamine, or known aromatic diamines such as benzene diamine.

[0089] The photocurable resin may be any resin having one or more unsaturated bonds that undergo a crosslinking reaction by light in one molecule. Suitable examples of the photocurable resin include, for example: acrylic resin, maleic resin, polybutadiene resin, polyester resin, polyurethane resin, epoxy resin, oxetane resin, phenoxy resin, polyimide resin, polyamide resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, and fluororesin, etc. In addition, the photocurable resin may also have functional groups that can be utilized in the crosslinking reaction based on heating.

[0090] When the resin composition layer contains a photocurable resin, it is preferably also contains an initiator. As the initiator, triazine-based photoinitiators, borate-based photoinitiators, carbazole-based photoinitiators, acetophenone-based photoinitiators, and oxime ester-based photoinitiators, etc. can be used.

[0091] Among them, acetophenone-based photoinitiators and oxime ester-based photoinitiators are preferred because they have less yellowing during the heat aging process.

[0092] Regarding the viewpoint of yellowing, based on the total amount (100% by mass) of the resin composition layer, the content rate of the initiator is preferably 0.5% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass.

[0093] Examples of the thermoplastic resin include: butyral resin, styrene-maleic acid copolymer, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyester resin, vinyl resin, alkyd resin, polystyrene resin, polyamide resin, rubber-based resin, cyclized rubber-based resin, celluloses, polyethylene (high density polyethylene (HDPE), low density polyethylene (LDPE)), polybutadiene, and polyimide resin, etc.

[0094] The weight average molecular weight (Mw) of the resin (A) is 10,000 to 1,000,000. Regarding the viewpoints of light resistance and adhesion, it is more preferably 25,000 to 300,000, and further preferably 50,000 to 150,000. By setting the weight average molecular weight (Mw) to 10,000 or more, the length of the molecular chain is appropriate, so the entanglement of the molecular chain in the heat aging process becomes extremely easy to untangle, and it is optimized, thereby making the followability to the adherend appropriate, and thus the adhesion can be improved. By setting the Mw to 1,000,000 or less, the compatibility with the embedding property improver (B) becomes good, the influence of yellowing caused by oxidative degradation due to light irradiation can be prevented, and the light resistance can be improved.

[0095] In addition, the ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) representing the dispersity of the resin (A) is preferably 1 to 5, more preferably 2 to 4.5, and further preferably 2.5 to 4. By setting Mw / Mn to 1 to 5, the flow rate when heating the resin is homogenized within the resin, so it is easy to control the fluidity of the resin and the embedding property is improved. In addition, since the speed of wetting the adherend is also homogenized, the adhesion is improved.

[0096] In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values in terms of polystyrene measured by gel permeation chromatography (GPC) method. The weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure are measured by the methods described in the following examples.

[0097] The glass transition temperature (Tg) of the resin (A) is -30°C to 40°C. From the viewpoints of light resistance, embedability, and adhesion, it is more preferably -20°C to 30°C, further preferably -10°C to 25°C, still further preferably 0°C to 20°C, and particularly preferably 5°C to 15°C. By setting the glass transition temperature (Tg) to -30°C or higher, the fluidity or wettability of the resin (A) in the pressing process can be made appropriate, and the embedability or adhesion can be improved. In addition, in the heat aging process, it is easy to form a network structure between the resin (A) and the embedability improver (B), and the light resistance is improved.

[0098] By setting the glass transition temperature (Tg) to 40°C or lower, when pressure is applied to the resin composition layer in the pressing process, the molecular motion of the resin (A) contained in the resin composition layer is activated, and it becomes a state where the entanglement of the molecular chains is easily unraveled. If the entanglement of the molecular chains is unraveled, it can be deformed in the form of following the uneven adherends such as the substrate or the light-emitting element, the empty area between the light-emitting element and the resin composition layer can be reduced, and the embedability can be improved. In addition, the compatibility with the embedability improver (B) becomes good, the influence of yellowing caused by photooxidative degradation can be prevented, and the light resistance is improved. Furthermore, when heat aging, the entanglement of the molecular chains of the resin composition layer and the coordination of the embedability improver (B) are optimized, the residual stress is removed, so the sealing layer is smoothed, and the adhesion to the adherend is improved.

[0099] When the glass transition temperature (Tg) is lower than -30°C, the fluidity of the resin (A) in the pressing process becomes too high, so the thickness of the sealing layer is not uniform, the resin at the end of the sealing layer flows and becomes thin, the function of fixing the light-emitting element is not exhibited, the adhesion deteriorates, and the embedability becomes poor. In addition, in the heat aging process, it is not easy to form a network structure between the resin (A) and the embedability improver (B), so the light resistance deteriorates.

[0100] When the glass transition temperature (Tg) is higher than 40°C, the fluidity of the resin (A) is low, and it is difficult for the resin (A) to follow the unevenness of the light-emitting element, and the embedability becomes poor. In addition, due to the low wettability to the adherend, the adhesion deteriorates, and the compatibility between the embedability improver (B) and the resin (A) becomes unstable, resulting in poor light resistance.

[0101] When the resin (A) contains a thermosetting resin or a photocurable resin, the glass transition temperature (Tg) of the resin (A) represents the glass transition temperature (Tg) before thermosetting and before photocuring. The glass transition temperature (Tg) of the resin (A) in the present disclosure is measured by the method described in the following examples.

[0102] Based on the total amount (100% by mass) of the resin composition layer, the content of resin (A) is preferably 76% to 99.9% by mass, more preferably 81% to 99% by mass, and still more preferably 86% to 95% by mass. When two or more resins (A) are included, the content of any resin (A) is preferably 10% by mass or more, and the total content is preferably within the above range. By setting the content of resin (A) to 76% to 99.9% by mass, the light resistance, embedding property, adhesion, and tearing property become good. When the content of resin (A) is less than 76% by mass, the network structure of resin (A) and the embedding property improver (B) is not easily optimized, so the light resistance deteriorates. In addition, since the embedding property improver (B) does not easily function in the pressing process, the embedding property deteriorates, and the intermolecular force derived from resin (A) becomes weak, so the adhesion or tearing property deteriorates.

[0103] [(meth)acrylic resin (a)]

[0104] In the present disclosure, the (meth)acrylic resin (a) is preferably an acrylic copolymer obtained by copolymerizing (meth)acrylate monomers. Suitable examples of the (meth)acrylate monomers include (meth)acrylic acid alkyl ester monomers. When forming a crosslinked structure, it is preferably a (meth)acrylic copolymer obtained by copolymerizing a functional group-containing monomer and a (meth)acrylate monomer.

[0105] (Meth)acrylic acid alkyl ester monomers are compounds formed by esterifying (meth)acrylic acid and introducing an alkyl group or a cycloalkyl group, and the alkyl group or cycloalkyl group can be any of a linear, branched, or cyclic saturated aliphatic hydrocarbon group. The saturated aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms. Specific examples include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. Among these, especially from the viewpoint of the compatibility of the embedding improver (B), it is particularly preferred to use methyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate.

[0106] Based on 100% by mass of the (meth)acrylic resin (a), the structural unit derived from the (meth)acrylic acid alkyl ester monomer is preferably 1% to 100% by mass, more preferably 20% to 99.9% by mass, and still more preferably 80% to 99.7%.

[0107] The (meth)acrylic resin (a) preferably contains a functional group-containing monomer. Examples of the functional group-containing monomer include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an epoxy group-containing monomer, and an amino group-containing monomer. By containing the functional group-containing monomer, the cohesion of the resin (A) is improved, and a tough resin composition layer can be obtained.

[0108] Examples of the carboxyl group-containing monomer include: (meth)acrylic acid, β-carboxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, and isocrotonic acid. Among these, from the viewpoint of adhesion, (meth)acrylic acid is particularly preferred.

[0109] As the hydroxyl group-containing monomer, for example, the following can be exemplified: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Among these, from the viewpoint of adhesion, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are more preferable.

[0110] As the epoxy group-containing monomer, for example, the following can be exemplified: glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate.

[0111] As the amino group-containing monomer, for example, the following can be exemplified: monoalkylamino esters of (meth)acrylic acid such as monoethylaminoethyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, monomethylaminoethyl (meth)acrylate, and monomethylaminopropyl (meth)acrylate.

[0112] With respect to 100% by mass of the (meth)acrylic resin (a), the total of the structural units derived from the functional group-containing monomer is preferably 0.1% by mass to 20% by mass. By setting it within the above range, the cohesive force can be adjusted by the reaction with the crosslinking agent.

[0113] With respect to 100% by mass of the (meth)acrylic resin (a), the constituent unit derived from the carboxyl group-containing monomer is preferably 0.1% by mass to 10% by mass. By being within the above range, the adhesion to the adherend can be improved.

[0114] In addition, with respect to 100% by mass of the (meth)acrylic resin (a), the constituent unit derived from the hydroxyl group-containing monomer is preferably 0.1% by mass to 10% by mass. By being within the above range, the adhesion to the adherend can be adjusted.

[0115] The (meth)acrylic resin (a) may also contain structural units derived from other monomers that can copolymerize with (meth)acrylic alkyl esters and functional group-containing monomers. For example, monomers having an alkyleneoxy group and other vinyl monomers can be cited. For example, the following can be exemplified: methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, and acrylamide. The structural units derived from the above other monomers are preferably 0.1% by mass to 20% by mass in 100% by mass of the (meth)acrylic copolymer.

[0116] As a more preferred example of the (meth)acrylic resin (a), a (meth)acrylic copolymer containing a structural unit of one or more acrylic acid alkyl esters (a1) derived from a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms and a structural unit of one or more methacrylic acid alkyl esters (a2) derived from a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms can be cited.

[0117] By including a structural unit of one or more acrylic acid alkyl esters (a1) derived from a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, the interaction with the adherend interface within a short contact time is easily exhibited, the gap between the light-emitting element and the resin composition layer during embedding can be reduced, and it helps to improve the embeddability.

[0118] By the (meth)acrylic resin (a) including a structural unit of one or more methacrylic acid alkyl esters (a2) derived from a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, it is easily wetted and spread to the adherend interface within a long contact time, the gap between the light-emitting element and the resin composition layer during embedding can be reduced, and it helps to improve the embeddability.

[0119] From the viewpoint of optimizing the interaction with the adherend interface within a short contact time and improving the embeddability and adhesion, the acrylic acid alkyl ester (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferably an acrylic acid alkyl ester having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, more preferably an acrylic acid alkyl ester having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 4 carbon atoms. In addition, the saturated aliphatic hydrocarbon group of the acrylic acid alkyl ester (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is more preferably linear or branched.

[0120] From the viewpoint of improving the embeddability and adhesion, with respect to 100% by mass of the (meth)acrylic resin (a), the total mass of the structural units of the acrylic acid alkyl esters (a1) derived from a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferably 1% to 95% by mass, more preferably 5% to 70% by mass, and still more preferably 7% to 60% by mass.

[0121] In terms of optimizing the wetting spread to the adherend interface over a long contact time and improving the embedment property and adhesion, the alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms is preferably an alkyl methacrylate having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 4 carbon atoms. Further, the saturated aliphatic hydrocarbon group of the alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms is more preferably linear or branched.

[0122] In terms of improving the embedment property and adhesion, with respect to the (meth)acrylic resin being 100% by mass of (a), the total mass of the structural units derived from the alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms is preferably 1% to 95% by mass, more preferably 30% to 90% by mass, and still more preferably 35% to 85% by mass.

[0123] The ratio of the total mass of the structural units derived from the acrylic alkyl ester (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 12 carbon atoms to the total mass of the structural units derived from the alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms in the (meth)acrylic resin (a) is preferably 1:0.4 to 1:20, more preferably 1:0.6 to 1:15, still more preferably 1:1 to 1:13, and particularly preferably 1:5 to 1:9.

[0124] By setting it to 1:0.4 to 1:20, the light resistance can be improved, the intermolecular interaction within the resin of the (meth)acrylic resin (a) can be made appropriate, and the fluidity of the resin with good embedment property can be exhibited. In addition, the wettability of the (meth)acrylic resin (a) to the adherend is optimized, and the adhesion is good.

[0125] As a more preferred example of the (meth)acrylic resin (a), a (meth)acrylic copolymer can be cited that contains, in addition to the constituent units derived from the acrylic alkyl ester (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 12 carbon atoms and the constituent units derived from the alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group with 1 to 8 carbon atoms, one or more constituent units derived from (meth)acrylic acid (a3).

[0126] With respect to 100% by mass of the (meth)acrylic resin (a), the total mass of the structural units derived from (meth)acrylic acid (a3) is preferably 0.1% to 15% by mass, more preferably 0.3% to 10% by mass, and still more preferably 0.5% to 5% by mass. By setting it to 0.1% to 15% by mass, the adhesion can be improved through intermolecular interaction with the adherend. In addition, from the viewpoint of improving the adhesion to the adherend, (meth)acrylic acid (a3) is more preferably methacrylic acid.

[0127] As a further preferred example of the functional group-containing monomer constituting the (meth)acrylic resin (a), an example in which (meth)acrylic acid (a3) and the hydroxyl group-containing monomer are not contained simultaneously can be cited. By not containing (meth)acrylic acid (a3) and the hydroxyl group-containing monomer simultaneously, the cohesion of the (meth)acrylic resin (a) can be adjusted and the adhesion can be improved.

[0128] (Meth)acrylic resin (a) can be obtained by polymerizing an acrylic monomer mixture. During the polymerization, a polymerization initiator can be used as needed. The content of the polymerization initiator is set to, for example, 0.01% to 10% by mass with respect to 100% by mass of the monomer mixture. The polymerization method is not limited. For example, polymerization can be carried out by solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization. From the viewpoint of ease of polymerization control, solution polymerization is particularly preferred. Examples of the solvent used in solution polymerization include acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, and cyclohexanone. The polymerization temperature can be set to, for example, about 60°C to 120°C, and the polymerization time can be set to about 2 hours to 12 hours.

[0129] The polymerization initiator is preferably a radical polymerization initiator. As the radical polymerization initiator, peroxides and azo compounds are suitable. Examples of azo compounds include: 2,2'-azobisisobutyronitrile (abbreviation: AIBN (2,2'-azobisisobutyronitrile)), 2,2'-azobis(2-methylbutyronitrile) and other 2,2'-azobisbutyronitriles; 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile) and other 2,2'-azobisvaleronitriles; 2,2'-azobis(2-hydroxymethylpropionitrile) and other 2,2'-azobispropionitriles; 1,1'-azobis(cyclohexane-1-carbonitrile) and other 1,1'-azobis-1-alkanenitriles. Examples of peroxides include: di-tert-butyl peroxide, diisopropylbenzene peroxide, tert-butyl isopropylbenzene peroxide, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-bis(tert-butylperoxy)hex-3-yne and other dialkyl peroxides; tert-butyl peroxybenzoate, tert-butyl peroxyacetate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane and other peroxy esters; cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide and other ketone peroxides; 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate and other peroxyketals; cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide and other hydroperoxides; benzoyl peroxide, decanoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide and other diacyl peroxides; bis(tert-butylcyclohexyl) peroxydicarbonate and other peroxydicarbonates.

[0130] [Burial improver (B)]

[0131] In the present embodiment, the burial improver (B) is a compound having the function of improving the fluidity of the resin (A) and improving the burial property between a plurality of light-emitting elements, and contains a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2). Regarding the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2), the burial property is improved by containing both in the resin composition layer. In addition, it also has the effects of improving light resistance, adhesion, and tear resistance.

[0132] The present disclosure contemplates the following mechanism. First, in the pressing process, the embedding improver (B) moves freely enough to enter between the molecular chains of the resin (A), thereby cutting off the intermolecular interaction of the resin (A), assisting in uniformly unraveling the resin (A), thereby improving fluidity, and the resin composition layer deforms in a manner following the light-emitting element. Thereafter, the phosphorus atom part of the phosphorus-containing compound (B1) is weakly coordinated with the phenolic hydroxyl part of the phenolic hydroxyl group-containing compound (B2), and at the same time enters the molecular chain of the resin (A) having a weight average molecular weight (Mw) specified in the present disclosure, thereby forming a uniform network structure, suppressing further deformation of the resin composition layer, and improving the embedding property. In addition, since the intermolecular interaction of the resin (A) is appropriately adjusted, the adhesion becomes good. Furthermore, the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2) have a free radical scavenging function, and the resin (A) and the embedding improver (B) form a uniform network structure, thereby efficiently exhibiting the free radical scavenging function and improving the light resistance. In addition, since the intermolecular interaction between the adherend and the resin (A) is moderately adjusted, the adhesion is improved. Furthermore, since the stress applied when peeling the release liner is evenly dispersed, the tearability is improved.

[0133] The mass ratio B1:B2 of the phosphorus-containing compound (B1) to the phenolic hydroxyl group-containing compound (B2) in the embedding improver (B) is preferably 0.1:1 to 10:1, more preferably 0.5:1 to 5:1, and still more preferably 1:1 to 3:1. By setting it to 0.1:1 to 10:1, the molecular chain of the resin (A) and the embedding improver (B) form a uniform network structure, and the embedding property is improved. In addition, since the free radical scavenging function of the embedding improver (B) can be fully exerted, the light resistance is excellent. Furthermore, the coordination of the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2) becomes appropriate, and the aggregation characteristics of the resin (A) are not hindered, so the tearability becomes good.

[0134] From the viewpoints of the embedding property and the adhesion, in the total amount (100% by mass) of the resin composition layer, the content of the embedding improver (B) is preferably 0.1% by mass to 15% by mass, more preferably 0.3% by mass to 10% by mass, and still more preferably 0.5% by mass to 5% by mass. By setting it to 0.1% by mass to 15% by mass, the embedding property, the adhesion, the light resistance, and the tearability are improved.

[0135] [Phosphorus-containing compound (B1)]

[0136] The phosphorus-containing compound (B1) used in the present disclosure is not particularly limited as long as it is a compound containing phosphorus in the molecule. It is preferably a compound having a molecular weight of less than 10,000, more preferably a compound having a molecular weight of 30 to 5,000, and still more preferably a compound having a molecular weight of 30 to 2,000. Only one kind of the phosphorus-containing compound (B1) may be used, or two or more kinds may be used in combination. From the viewpoints of compatibility or embedding property, it is preferably to use one or more substances in a solid state at normal temperature and one or more substances in a liquid state in combination.

[0137] As the phosphorus-containing compound (B1), the following can be suitably used: tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, tristearyl phosphite, phenylisooctyl phosphite, phenylisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, triphenyl phosphite, trimethylphenyl phosphite, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenol alkylene phosphite, trinonylphenyl phosphite, tri-dinonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, bis(decyl)pentaerythritol diphosphite (alias: 3,9-bis(decoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), bis(tridecyl)pentaerythritol diphosphite (alias: 3,9-bis(tridecoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), distearylpentaerythritol diphosphite (alias: 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), bis(nonylphenyl)pentaerythritol diphosphite (alias: 3,9-bis(nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (alias: 3,9-bis(2,4-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), bis(2,6-di-tert-butylphenyl)pentaerythritol diphosphite (alias: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), phenylbisphenol A pentaerythritol diphosphite, tetra-tridecyl 4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa-tridecyl 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphite diethyl ester, sodium bis(4-tert-butylphenyl) phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)-sodium phosphite, 1,3-bis(diphenoxyphosphinyloxy)-benzene, ethyl bis(2,4-di-tert-butyl-6-methylphenyl) phosphite, etc. In addition, other oligomer-type compounds having a phosphite structure with a molecular weight of less than 10,000 can also be used.

[0138] In particular, from the viewpoints of light resistance and embedability, compounds having a triphenyl phosphite skeleton, compounds having a trialkyl phosphite skeleton, compounds having a diphenyl monoalkyl phosphite skeleton, compounds having a monophenyl dialkyl phosphite skeleton, and compounds having a 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane skeleton are preferred. In addition, the phenyl skeleton may also contain substituents such as tert-butyl groups.

[0139] Furthermore, specifically, tris(2,4-di-tert-butylphenyl) phosphite, tris(2-ethylhexyl) phosphite, bis(decyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, bis(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butylphenyl)pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite are more preferred, and distearyl pentaerythritol diphosphite and bis(2,6-di-tert-butylphenyl)pentaerythritol diphosphite are even more preferred.

[0140] Specific examples of commercially available products of the phosphorus-containing compound (B1) include: "Adekastab PEP-8, PEP-36, C, TPP, HP-10, 135A, 1500, 2112, 2112RG, 3010, 1178, 4C, 24G, 2" manufactured by ADEKA Corporation; "IRGAFOS (registered trademark) 168, 168FF, 38, 126, P-EPQ, 12" manufactured by BASF Japan Co., Ltd.; "SUMILIZER (registered trademark) GP" manufactured by Sumitomo Chemical Co., Ltd.; "JP-360, JP-351, JP-3CP, JP-308E, JPE-308E, JP-310, JP-312L, JP-333E, JPM-308, JPM-311, JPM-313, JPP-100, JA-805, JPH-1200, JPP-88, JPE-10, JPE-13R, JP-318E, JPP-2000PT, JP-650, JPH-3800, JC-356" manufactured by Kitashiro Chemical Industry Co., Ltd.; "Everaox (registered trademark) 168, 201, 202, 203, 204" manufactured by Everlight Chemical Co., Ltd.; "Hostanox (registered trademark) P-EPQ (registered trademark)" manufactured by Clariant Corporation; "Ultranox (registered trademark) 626" manufactured by Fujifilm Wako Pure Chemical Corporation.

[0141] The content rate of the phosphorus-containing compound (B1) relative to the total amount (100% by mass) of the resin composition layer is preferably 0.05% by mass to 10% by mass, more preferably 0.2% by mass to 7% by mass, and still more preferably 0.4% by mass to 6% by mass.

[0142] [Compound (B2) containing phenolic hydroxyl group]

[0143] The compound (B2) containing a phenolic hydroxyl group used in the present disclosure is a compound that contains a phenolic hydroxyl group in the molecule and does not contain phosphorus. The molecular weight is preferably less than 10,000, more preferably 94 to 5,000, and still more preferably 94 to 3,000. Only one kind of the compound (B2) containing a phenolic hydroxyl group can be used, or two or more kinds can be used in combination.

[0144] As the compound (B2) containing phenolic hydroxyl groups, the following can be used: 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-sec-butylphenol, 2,6-di-tert-butyl-4-hydroxymethylphenol, pentaerythritol tetra[3-(3,5-di(tert-butyl)-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-(hexane-1,6-diyl)bis(3,5-di-tert-butyl-4-hydroxybenzamide), octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, 2,4-dimethyl-6-(1-methylpentadecyl)phenol, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, calcium bis[[3,5-di(tert-butyl)-4-hydroxybenzyl]phosphonic acid ethyl], 2,4-bis(octylthiomethyl)-6-methylphenol, bis(3-tert-butyl-4-hydroxy-5-methylphenylpropionic acid) ethylenebis(oxyethylene) ester, 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[(3,5-di-tert-butyl-4-hydroxyphenyl)methyl]-1,3,5-triazacyclohexane-2,4,6-trione, 6-(4-hydroxy-3,5-di-tert-butylanilino)-2,4-bis(octylthio)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4,4',4''-(1-methylpropylidene-3-ylidene)tris(6-tert-butyl-m-cresol), 6,6'-di-tert-butyl-4,4'-butylidene di-m-cresol, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene, etc.

[0145] In particular, from the viewpoints of light resistance and embedding property, a phenolic hydroxyl group-containing compound having a hindered skeleton in which two tert-butyl groups are bonded to the ortho positions of the phenolic hydroxyl group or a semi-hindered skeleton in which one tert-butyl group is bonded to one of the ortho positions of the phenolic hydroxyl group and one methyl group is bonded to the other is preferred. Further preferred are pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene.

[0146] Specific examples of commercially available products of the phenolic hydroxyl group-containing compound (B2) include: "Adekastab AO-20, AO-30, AO-40, AO-50, AO-50F, AO-50T, AO-60, AO-60G, AO-80, AO-330" manufactured by ADEKA Corporation; "KEMINOX 9425, 179" manufactured by Chemipro Kasei Co., Ltd.; "SUMILIZER (registered trademark) GA-80, GM, GS, GA-80, MDP-S, WX-R, WX-RC, BBM-S" manufactured by Sumitomo Chemical Company, Limited; "IRGANOX (registered trademark) 1010, 1010FF, 1035, 1035FF, 1076, 1076FD, 1098, 1135, 1141, 1330, 1425WL, 1520L, 245, 245FF, 259, 3114, 565" manufactured by BASF Japan Ltd.; "Yoshinox BB, 425" manufactured by Mitsubishi Chemical Corporation; and "Hostanox (registered trademark) 03, O310" manufactured by Clariant Corporation.

[0147] The content rate of the phenolic hydroxyl group-containing compound (B2) with respect to the total amount (100% by mass) of the resin composition layer is preferably 0.04% by mass to 5% by mass, more preferably 0.1% by mass to 3.5% by mass, and still more preferably 0.2% by mass to 3% by mass.

[0148] [Crosslinking agent]

[0149] The resin composition layer of the present disclosure may also contain a crosslinking agent. In particular, when the resin (A) contains a thermosetting resin, in order to promote the formation of a crosslinked structure, it is preferable to use a crosslinking agent. One type of crosslinking agent may be used alone, or two or more types may be used in combination. During hot pressing or heat aging in the pressing process, the crosslinking agent undergoes a crosslinking reaction with the reactive functional groups of the resin (A), thereby making the adhesion to adherends such as light-emitting elements firmer. In addition, the cohesion of the resin composition layer can be improved, and thus the tearability becomes good.

[0150] The crosslinking agent has a plurality of functional groups capable of reacting with the functional groups of the resin (A). Examples of the crosslinking agent include known compounds such as silane coupling agents, epoxy compounds, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, and amine compounds. From the viewpoint of adjusting the loss tangent (tanδ) of the resin composition layer, silane coupling agents, epoxy compounds, aziridine compounds, imidazole compounds, and isocyanate compounds are preferred, and epoxy compounds are more preferred.

[0151] The epoxy compound is a compound having two or more epoxy groups in one molecule. As the property of the epoxy compound, by using a liquid form, the peak temperature of tanδ of the resin composition layer can be reduced, and the light-emitting element can be well adhered to the resin composition layer. On the other hand, by using a solid epoxy compound, the peak temperature of tanδ of the resin composition layer can be increased, the stickiness of the resin composition layer can be controlled, and the tearability can be adjusted.

[0152] Examples of the epoxy compound preferably include glycidyl ether type epoxy compounds, glycidyl amine type epoxy compounds, glycidyl ester type epoxy compounds, and cyclic aliphatic (alicyclic) epoxy compounds. In addition, from the viewpoint of light resistance, the epoxy compound is more preferably a high-purity hydrogenated epoxy resin.

[0153] Examples of the glycidyl ether type epoxy compound include cresol novolac type epoxy compounds, tris(glycidyloxy phenyl)methane, and tetrakis(glycidyloxy phenyl)ethane. Examples of the glycidyl amine type epoxy compound include tetraglycidyldiaminodiphenylmethane and tetraglycidyl metaxylylenediamine.

[0154] Examples of the glycidyl ester type epoxy compound include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.

[0155] Examples of the cyclic aliphatic (alicyclic) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis(epoxycyclohexyl)adipate.

[0156] As aziridine compounds, for example, the following can be cited: trimethylolpropane-tris-β-aziridinyl propionate, tetramethylolmethane-tris-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, 4,4'-bis(ethyleneimino carbonylamino) diphenylmethane, and the like.

[0157] Examples of imidazole compounds include 2-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, imidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimesate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and other imidazole compounds. Further, compounds with improved storage stability, such as those in which an imidazole compound is reacted with an epoxy resin to make it insoluble in a solvent or those in which an imidazole compound is encapsulated in microcapsules, can be cited.

[0158] The isocyanate compound is an isocyanate having two or more isocyanate groups. The isocyanate compound is preferably, for example, an aromatic polyisocyanate, an aliphatic polyisocyanate, an araliphatic polyisocyanate, an alicyclic polyisocyanate, or the like, as well as biuret bodies, allophanate (nurate) bodies, and adducts thereof.

[0159] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4”-triphenylmethane triisocyanate.

[0160] Examples of aliphatic polyisocyanates include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (alias: HDI (hexamethylene diisocyanate)), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate.

[0161] Examples of araliphatic polyisocyanates include: ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylbenzene dimethyl diisocyanate, 1,3-tetramethylbenzene dimethyl diisocyanate.

[0162] Examples of alicyclic polyisocyanates include: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (alias: IPDI (isophorone diisocyanate), isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane.

[0163] The biuret body is a self-condensate with a biuret bond formed by self-condensation of isocyanate monomers. Examples of the biuret body include the biuret body of hexamethylene diisocyanate.

[0164] The isocyanurate body is a trimer of isocyanate monomers. Examples include: the trimer of hexamethylene diisocyanate, the trimer of isophorone diisocyanate, the trimer of toluene diisocyanate, etc.

[0165] The adduct is a polyisocyanate compound with two or more functional groups formed by reacting isocyanate monomers with a compound containing low molecular active hydrogen with two or more functional groups. Examples of the adduct include: a compound formed by reacting trimethylolpropane with hexamethylene diisocyanate, a compound formed by reacting trimethylolpropane with toluene diisocyanate, a compound formed by reacting trimethylolpropane with xylylene diisocyanate, a compound formed by reacting trimethylolpropane with isophorone diisocyanate, a compound formed by reacting 1,6-hexanediol with hexamethylene diisocyanate.

[0166] From the viewpoint of forming a sufficient crosslinked structure, the isocyanate compound is preferably a trifunctional isocyanate compound. The isocyanate compound is more preferably an adduct which is a reaction product of an isocyanate monomer and a trifunctional low molecular weight active hydrogen-containing compound, and an isocyanurate. The isocyanate compound is preferably a trimethylolpropane adduct of hexamethylene diisocyanate, an isocyanurate of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, an isocyanurate of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, an isocyanurate of isophorone diisocyanate, and more preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate.

[0167] In the present disclosure, from the viewpoint of the coating film resistance to scratches, it is preferable to contain two or more crosslinking agents. Specifically, in terms of adjusting the loss tangent (tanδ) of the resin composition layer, suitable examples include those containing two or more selected from silane coupling agents, epoxy compounds, aziridine compounds, and isocyanate compounds. Further preferably, examples include those using any one or more of silane coupling agents, epoxy compounds, aziridine compounds, and isocyanate compounds, and an epoxy compound of a type different from the above epoxy compound.

[0168] Based on the total amount (100% by mass) of the resin composition layer, the content of the crosslinking agent (the total content in the case of using two or more) is preferably 0.01% by mass to 30% by mass, more preferably 0.05% by mass to 20% by mass, and still more preferably 0.1% by mass to 10% by mass. By setting it to the above content (0.01% by mass to 30% by mass), the compatibility, embedding property, and tearing property of the embedding improver (B) can be appropriately adjusted.

[0169] [Other components]

[0170] Within the scope not impairing the object of the present disclosure, other components may also be contained in the resin composition layer of the present disclosure. For example, inorganic fillers, colorants, dispersants, surface conditioning additives, hardening accelerators, hardening retardants, softeners, antistatic agents, lubricants, anti-blocking agents, adhesion improvers, etc. may be added. From the viewpoint of controlling film properties such as the diffusibility, reflectivity, light-shielding property, and viscoelasticity of the resin composition layer, it is preferable to contain inorganic fillers, dispersants, surface conditioning additives, hardening accelerators, hardening retardants, and adhesion improvers.

[0171] Examples of the inorganic filler include inorganic compounds containing no phosphorus such as silica, alumina, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorillonite, kaolinite, bentonite, boron nitride, aluminum nitride, and titanium nitride.

[0172] Among these, from the viewpoint of the coating film resistance to scratches, titanium oxide, titanium nitride, silica, talc, mica, kaolinite, or montmorillonite is preferable, and titanium oxide, titanium nitride, and silica are more preferable.

[0173] In the present disclosure, from the viewpoint of the coating film resistance, two or more inorganic fillers may also be contained. Specifically, examples thereof preferably include a combination containing silica and one or more selected from titanium oxide, titanium nitride, silica, talc, mica, kaolinite, or montmorillonite.

[0174] From the viewpoint of the embeddability, based on the total amount (100% by mass) of the resin composition layer, the content rate of the inorganic filler (the total content rate in the case of containing two or more) is preferably 0.01% by mass to 10% by mass, and more preferably 0.1% by mass to 5% by mass. By containing 0.01% by mass to 10% by mass of the inorganic filler, the effect of improving the fluidity of the resin composition layer in the pressing process is easily exhibited, and the embeddability is improved.

[0175] The average primary particle diameter of the inorganic filler (hereinafter, the particle diameter) is preferably 1 nm to 100 nm. By setting the particle diameter to 1 nm or more, it is easy to maintain the viscosity of the resin composition at a level suitable for coating. In addition, by setting the particle diameter to 100 nm or less, the coating film resistance is improved. Further, the particle diameter of the inorganic filler can be determined based on the average value of the following primary particles, that is, the average value of about 20 primary particles observable from an image magnified 50,000 to 1,000,000 times by a transmission electron microscope (TEM).

[0176] The inorganic filler can also be dispersed and processed into the resin (A) by mechanical crushing. A dispersant is preferably used in the dispersion process. In the present disclosure, the dispersant has a function of imparting a repulsive force between particles to prevent the particles divided by the dispersion process from aggregating again.

[0177] As the dispersant, known compounds can be used, for example, polymeric dispersants, pigment derivative type dispersants, or compounds free of phenolic hydroxyl groups and phosphorus among surfactants selected from cationic, anionic, or nonionic types. The weight average molecular weight (Mw) of these dispersants can be set to about 1,000 to 9,999, for example.

[0178] As the surface conditioning additive, compounds free of phenolic hydroxyl groups and phosphorus among surfactants having a weight average molecular weight (Mw) of 1,000 to 9,999 such as silicone-based, silicone acrylate-based, acrylate-based, fluorine-based, and acetylene glycol-based can be cited. Among them, from the viewpoint of adhesion to the adherend, surfactants containing silicone-based and silicone acrylate-based are particularly preferred.

[0179] As the silicone-based surface conditioning additive, for example, a modified polysiloxane compound obtained by introducing an organic group into a part of the methyl groups of polydimethylsiloxane is preferably used. Examples of the modification include polyether modification, methylstyrene modification, alcohol modification, alkyl modification, aralkyl modification, fatty acid ester modification, epoxy modification, amine modification, amino modification, and mercapto modification, but are not particularly limited to these. These modification methods can be used in combination. Among them, from the viewpoints of compatibility and the like, polyether-modified polysiloxane compounds and aralkyl-modified polysiloxane compounds are preferred. As the silicone acrylate-based surface conditioning additive, for example, from the viewpoints of compatibility and the like, a graft copolymer of an acrylic resin and a siloxane-based compound, that is, a siloxane-modified acrylic resin, is preferred. From the viewpoint of appropriate coating, based on the total amount (100% by mass) of the resin composition layer, the content of the surface conditioning additive is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass.

[0180] In order to adjust the crosslinking speed or the physical properties of the resin composition layer, etc., the resin composition layer of the present disclosure preferably contains a curing accelerator. The curing accelerator is not particularly limited and can be appropriately selected. Specific examples of the curing accelerator include amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. These can be used alone or two or more of them can be mixed and used.

[0181] From the viewpoint of appropriate coating, based on the total amount (100% by mass) of the resin composition layer, the content of the curing accelerator is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass.

[0182] As the adhesion improver, compounds free of phenolic hydroxyl groups and phosphorus among oligomers having a weight average molecular weight (Mw) of 1,000 to 9,999 can be cited. Examples include acrylic resins, urethane acrylate resins, rosin-based resins, terpene-based resins, alicyclic petroleum resins, and aromatic petroleum resins.

[0183] The weight average molecular weight (Mw) of the adhesion improver is more preferably 2,000 to 8,000, and further preferably 3,000 to 5,000. From the viewpoints of adhesion to the adherend and peelability, based on the total amount (100% by mass) of the resin composition layer, the content of the adhesion improver is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 15% by mass.

[0184] Examples

[0185] Hereinafter, the present disclosure will be specifically described by way of examples and comparative examples, but the present disclosure is not particularly limited to the examples. In addition, in the following description, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0186] The values obtained in this example are the values obtained by the following method.

[0187] [Glass transition temperature (Tg) of resin (A)]

[0188] The coating solution of resin (A) was coated on the release layer of a second release liner (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O3) with a thickness of 75 μm so that the dried thickness became 25 μm, and dried in a hot air oven at 100 °C for 3 minutes. Then, the release layer side of a first release liner (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O1) with a thickness of 50 μm was adhered to the resin (A) side. Subsequently, the first release liner and the second release liner were peeled off, and the Tg of the obtained resin (A) was measured using a differential scanning calorimeter (manufactured by TA Instruments, "Discovery DSC2500"). Approximately 2 mg of the sample was placed in an aluminum pan, weighed, and placed in the differential scanning calorimeter. Using an aluminum pan of the same type without the sample as a reference, after maintaining at 100 °C for 5 minutes, it was rapidly cooled to -50 °C using liquid nitrogen. Thereafter, it was heated at a heating rate of 5 °C / minute, and the glass transition temperature (Tg) of resin (A) was determined based on the obtained differential scanning calorimetry (DSC) chart.

[0189] [Weight average molecular weight (Mw) and number average molecular weight (Mn)]

[0190] Regarding the measurement of weight-average molecular weight (Mw) and number-average molecular weight (Mn), the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are determined by using the GPC "LC-GPC system" manufactured by Shimadzu Corporation and performing conversion with polystyrene of known molecular weight as the standard substance.

[0191] Device name: Manufactured by Shimadzu Corporation, LC-GPC system "Prominence"

[0192] Column: Four GMHXL manufactured by Tosoh Corporation and one HXL-H manufactured by Tosoh Corporation are connected.

[0193] Mobile phase solvent: Tetrahydrofuran

[0194] Flow rate: 1.0 mL / minute

[0195] Column temperature: 40 °C

[0196] [Solid content]

[0197] Weigh the mass (W0) of the aluminum cup using an analytical balance. Subsequently, place approximately 1 g of each sample into the aluminum cup and weigh the mass of the sample with the aluminum cup (W1) using an analytical balance. After heating the sample with the aluminum cup in an oven at 150 °C for 120 minutes, take it out of the oven and allow it to return to room temperature. Weigh the residual mass (W2) of the heated sample with the aluminum cup using an analytical balance. Then, calculate the solid content using the formula (W2 - W0) / (W1 - W0) × 100 (%).

[0198] [Acid value]

[0199] Here, the "acid value" represents the acid value per 1 g of the solid content of resin (A), and is determined by potentiometric titration in accordance with Japanese Industrial Standards (JIS) K 0070.

[0200] [Resin (A)]

[0201] [Manufacturing example of (meth)acrylic resin (a) (R-1)]

[0202] In a reaction vessel (hereinafter simply referred to as "reaction vessel") including a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, 80 parts of ethyl acetate, 35 parts of methyl acrylate, 34.4 parts of 2-ethylhexyl acrylate, 30 parts of 2-ethylhexyl methacrylate, 0.3 part of acrylic acid, 0.3 part of hydroxybutyl acrylate, and 0.1 part of 2,2'-azobisisobutyronitrile as an initiator were charged, and the environment inside the reaction vessel was replaced with nitrogen gas. Thereafter, while stirring under a nitrogen atmosphere, it was heated to 65 °C and the reaction was started. Thereafter, the reaction solution was reacted at 65 °C for 4 hours. After the reaction was completed, it was cooled and diluted with ethyl acetate to obtain a solution of (meth)acrylic resin (a) (R-1) having a weight average molecular weight (Mw): 20,000, a dispersity (Mw / Mn): 2, a glass transition temperature (Tg): -32 °C, an acid value: 2 mgKOH / g, and a solid content: 25%.

[0203] [Production Example of (Meth)acrylic Resin (a) (R-2 to R-12)]

[0204] Except for changing to the compositions and blending amounts (parts by mass) shown in Table 1, (meth)acrylic resin (a) (R-2 to R-12) was produced by the same method as the production of (meth)acrylic resin (a) (R-1). In addition, the blank indicates non-blending, and the solid content is 25% for all.

[0205]

[0206] The abbreviations in the table are as follows.

[0207] [Alkyl Acrylate (a1)]

[0208] MA: Methyl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 1)

[0209] BA: n-Butyl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 4)

[0210] HA: Hexyl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 6)

[0211] CHA: Cyclohexyl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 6)

[0212] 2EHA: 2-Ethylhexyl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 8)

[0213] LA: Lauryl Acrylate (carbon number of saturated aliphatic hydrocarbon group is 12)

[0214] [Alkyl Methacrylate (a2)]

[0215] MMA: Methyl Methacrylate (carbon number of saturated aliphatic hydrocarbon group is 1)

[0216] nBMA: n-butyl methacrylate (the number of carbon atoms in the saturated aliphatic hydrocarbon group is 4)

[0217] 2EHMA: 2-ethylhexyl methacrylate (the number of carbon atoms in the saturated aliphatic hydrocarbon group is 8)

[0218] [(meth)acrylic acid (a3)]

[0219] AA: acrylic acid

[0220] MAA: methacrylic acid

[0221] [Others]

[0222] 4HBA: hydroxybutyl acrylate

[0223] [Production Example of Urethane Resin (R-13)]

[0224] Charge 166 parts of terephthalic acid, 146 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol into a glass flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube, and a decompression device. Stir while introducing nitrogen, slowly raise the temperature under normal pressure, and react at 200°C to 230°C for about 8 hours to obtain a liquid with an acid value of 43 mg KOH / g. Subsequently, charge 0.01 part of tetra-n-butoxytitanium, stir at 180°C for 30 minutes after purging with nitrogen and sealing. Then, react at 230°C and 5 mmHg for 2 hours to obtain a polyester diol with an acid value of 1.1 mg KOH / g, a hydroxyl value of 114.2 mg KOH / g, a weight average molecular weight (Mw) of 982, and a hue of 10 (American Public Health Association (APHA) method, the same hereinafter).

[0225] Subsequently, charge 734 parts of the above-mentioned polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, and react at 50°C for 8 hours in a nitrogen atmosphere. Add 1200 parts of toluene thereto to obtain a solution of a urethane prepolymer having an isocyanate group at the terminal.

[0226] Next, the solution of the obtained prepolymer was heated to 70°C, and while maintaining this temperature, a solution prepared by mixing 20.0 parts of 1,3-diaminopropane, 3.1 parts of benzylamine, 600 parts of 2-propanol, and 961 parts of toluene was added dropwise over 1 hour. After the addition was completed, the reaction was further carried out at 70°C for 6 hours to obtain a solution of urethane resin (R-13) having a weight average molecular weight (Mw): 150,000, a dispersity (Mw / Mn): 4.5, a glass transition temperature (Tg): 18°C, an acid value: 10 mgKOH / g, and a solid content: 25%.

[0227] [Example 1]

[0228] [Manufacturing Example of Resin Composition]

[0229] While stirring using a disper, a solution of the (meth)acrylic resin (a) (R-2) as resin (A): 374 parts (93.5 parts of resin (A) and 280.5 parts of solvent), a phosphorus-containing compound (B1) as an embedding property improver (B), i.e., Adekastab PEP-36: 1 part, a phenolic hydroxyl group-containing compound (B2), i.e., AO-80: 0.5 part, a crosslinking agent as other component, i.e., epoxy-based crosslinking agent jER (registered trademark) YX8034 (manufactured by Mitsubishi Chemical Corporation): 5 parts, and 2-butanone as a solvent: 55 parts were sequentially added, and stirred until thoroughly homogeneous. Subsequently, filtration was carried out using a membrane filter with a pore size of 10 μm to remove coarse foreign matters that cause coating unevenness, and a resin composition with a non-volatile content of 23% was obtained. In addition, regarding the embedding property improver (B) and other components, they were set as the solid content conversion amounts.

[0230] [Manufacturing Example of Sealing Sheet]

[0231] The resin composition was coated on the release layer of a second release liner (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O3) with a thickness of 75 μm so that the dried thickness became 25 μm, and dried in a hot air oven at 100°C for 3 minutes to form a resin composition layer. Subsequently, the release layer side of a first release liner (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O1) with a thickness of 50 μm was adhered to the exposed resin composition layer, and aged at 0°C for 7 days to obtain the sealing sheet of Example 1 laminated in the order of the first release liner / resin composition layer / second release liner.

[0232] [Thickness Tt of Sealing Sheet, Thickness Ta of Resin Composition Layer, Thickness Tl of First Release Liner, Thickness Th of Second Release Liner]

[0233] At ten equally spaced positions within the range from one end to the other end in the width direction of the sealing sheet cut into a size of 10 cm × 10 cm, the thicknesses at these ten positions are measured, and the average value thereof is set as the thickness Tt of the sealing sheet. Subsequently, the first release liner is peeled off from the sealing sheet, and the thicknesses of the first release liner after peeling at ten positions corresponding to the same positions as those described above are measured. The average value thereof is set as Tl. Thereafter, further, the second release liner is peeled off from the resin composition layer, and the thicknesses of the second release liner after peeling at ten positions corresponding to the same positions as those described above are measured. The average value thereof is set as Th. The thickness Ta of the resin composition layer is obtained by the following (Equation 1). In addition, the thickness is measured using MH-15M (manufactured by Nikon Corporation).

[0234] Ta = Tt - Tl - Th (Equation 1)

[0235] [Loss tangent (tanδ) of the resin composition layer]

[0236] The sealing sheet separately produced in the production example of the sealing sheet so that the thickness after drying becomes 50 μm is cut into a size of 0.5 cm × 2 cm, the first release liner and the second release liner are peeled off, and for the obtained resin composition layer, using a dynamic viscoelasticity measuring device DVA-200 / L2 (manufactured by IT Measurement & Control Corporation), at a frequency of 10 Hz, a measurement temperature range of -50°C to 150°C, a heating rate of 5°C / minute, and a tensile mode, the dynamic viscoelasticity is measured and the loss tangent (tanδ) is plotted. The loss tangent (tanδ40) at 40°C, the peak temperature (tanδ peak temperature) of the loss tangent (tanδ), and the peak intensity (tanδ peak intensity) of the loss tangent (tanδ) are read from the obtained curve graph.

[0237] [Evaluation method, criteria]

[0238] [Light resistance]

[0239] The sealing sheet is cut into 2 cm × 5 cm, a glass plate with a thickness of 1.1 mm (blue plate glass, manufactured by Kawamura Kuzo Shoten Co., Ltd.) is attached to the surface after peeling off the first release liner, hot pressing (100°C, 5 MPa, 5 minutes) is performed and crimping is carried out. Further, the second release liner of the sealing sheet is peeled off, and the test piece including the glass plate and the resin composition layer is left standing at 180°C for 120 minutes, thereby closely bonding the glass plate and the resin composition layer. Subsequently, using an ultraviolet-visible spectrophotometer V-570 manufactured by JASCO Corporation, the spectral transmittance at 380 nm of the resin composition layer on the glass plate is measured, and the obtained value is set as the initial transmittance.

[0240] The resin composition layer on the glass plate was placed in a xenon weather meter XL75 manufactured by Suga Test Instruments Co., Ltd. and exposed for 300 hours under the conditions of a black panel temperature of 50°C and an irradiation amount of 100,000 Lux. After the exposure, the spectral transmittance at 380 nm was measured in the same manner as the initial transmittance, and the obtained value was used as the transmittance after exposure. The change value of the transmittance was calculated using the formula "|Initial transmittance - Transmittance after exposure| = Change value of transmittance". The evaluation criteria are as described below, and A to C are considered good.

[0241] A: The change value of the transmittance is less than 0.2

[0242] B: The change value of the transmittance is 0.2 or more and less than 0.4

[0243] C: The change value of the transmittance is 0.4 or more and less than 0.6

[0244] D: The change value of the transmittance is 0.6 or more

[0245] [Embeddability]

[0246] A glass substrate (size 1 cm × 1 cm, width of the concave part 20 μm, height of the convex part 20 μm, width of the convex part 20 μm) with concavo-convex processing imitating the concavo-convex of a micro-LED substrate was prepared. A schematic cross-sectional view of the test substrate is shown in Figure 3 below.

[0247] The sealing sheet is cut into a size of 2 cm × 2 cm. The first release liner or the second release liner is peeled off to expose the resin composition layer, and the resin composition layer side is placed on the uneven portion of the glass substrate. Thereafter, on the surface exposed by peeling the release liner on the opposite side, a TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) with a thickness of 50 μm as a buffer material and a vinyl chloride film (Celeb T, manufactured by Okamoto Co., Ltd.) with a thickness of 2.0 mm are sequentially laminated, and further cardboard is laminated to prevent sticking. Next, the substrate surface is pressed at 5 MPa and 100 °C for 20 minutes from above the test piece to fill the resin composition layer into the uneven portions of the glass substrate, thereby forming a sealing layer. After pressing, the buffer material and the cardboard are peeled off. The resin composition layer protruding from the glass substrate of the obtained test piece is roughly removed using a cutter, and further filed to remove the resin composition layer remaining on the side surface of the glass substrate, thereby exposing the side surface of the glass substrate, and thus becoming a state in which the uneven portions of the glass substrate can be observed. The embedding property is evaluated by observing any 20 concave portions of the glass substrate using an electron microscope. The case where the maximum gap between the resin composition layer and the glass substrate in the concave portion of the glass substrate is 5 μm or less is defined as the groove being embedded. The evaluation criteria are as follows, and A to C are considered good.

[0248] A: 18 or more grooves are embedded

[0249] B: 17 or less and 15 or more grooves are embedded

[0250] C: 14 or less and 12 or more grooves are embedded

[0251] D: 11 or less grooves are embedded

[0252] [Adhesion]

[0253] The sealing sheet is cut into 2 cm × 8 cm. A glass plate (blue plate glass, manufactured by K. Kawamura Shoten Co., Ltd.) with a thickness of 1.1 mm and a size of 2.5 cm × 10 cm is attached to the surface after peeling off the first release liner, and hot pressing (100 °C, 5 MPa, 5 minutes) is performed for crimping. Further, the second release liner of the sealing sheet is peeled off, and the test piece including the glass plate and the resin composition layer is allowed to stand at 180 °C for 120 minutes, thereby closely bonding the glass plate and the resin composition layer to produce a test piece including the glass plate and the resin composition layer.

[0254] According to JIS K 5600-5-6 (cross-cut method), a square grid pattern (25 grids) with a right angle of 1 mm square was made in the resin composition layer using a cross-cut guide and a cutter. The adhesive tape "CT1835" manufactured by Nichiban Co., Ltd. was attached to the portion where the grid cutting was performed and closely adhered to the resin composition layer. Within 5 minutes after attachment, it was peeled off at an angle close to 60° for 0.5 seconds to 1.0 seconds. The condition of the peeled resin composition layer was observed to evaluate the adhesion. The evaluation criteria are as follows, and A to C are considered good.

[0255] A: The number of completely peeled grids is 0, and no partial peeling is found at the end of the cut.

[0256] B: The number of completely peeled grids is 0, and only partial peeling is present at the end of the cut.

[0257] C: The number of peeled grids is 1 or more and 2 or less

[0258] D: The number of peeled grids is 3 or more

[0259] [Tearability]

[0260] The sealing sheet was cut into 2 cm × 8 cm, and a glass plate (blue plate glass, manufactured by Kawamura Kuzo Shoten Co., Ltd.) with a thickness of 1.1 mm and a size of 2.5 cm × 10 cm was attached to the surface after peeling off the first release liner, and hot pressing (100 °C, 5 MPa, 5 minutes) and crimping were performed. Three test pieces were prepared, and each was subjected to heat aging treatment under the following three levels of conditions. Condition (1) is to stand still at 220 °C for 60 minutes, condition (2) is to stand still at 180 °C for 120 minutes, and condition (3) is to stand still at 120 °C for 240 minutes. After heat aging, it was left standing for 1 hour or more under the conditions of 23 °C and 50% relative humidity.

[0261] Subsequently, the second release liner was peeled off from the resin composition layer at a peeling angle of 90° and a speed of 300 mm / minute. The resin composition layer of the obtained test piece was observed for tearing.

[0262] The evaluation criteria are as follows, and A to C are considered good.

[0263] A: No tearing was found under any heat aging condition.

[0264] B: Tearing was found under any one heat aging condition.

[0265] C: Tearing was found under any two heat aging conditions.

[0266] D: Tearing was found under any heat aging condition.

[0267] Any of the above evaluations is conducted in the following four stages: Evaluations that are particularly excellent are designated as A, followed by excellent evaluations designated as B, then good evaluations designated as C, and evaluations that do not meet the target performance are designated as D. In addition, resin composition layers with all performance evaluations of A to C are in line with the present disclosure.

[0268] [Examples 2 to 41], [Comparative Examples 1 to 7]

[0269] Except for changing to the content ratios and thickness Ta shown in Tables 2 to 5, the sealing sheets were produced by the same method as in Example 1 and evaluated in the same manner. In addition, any other components were also added simultaneously.

[0270] In Tables 2 to 5, Resin (A), the embedding property improver (B), and other components are in terms of the amount in solid content, and the blank spaces indicate no formulation.

[0271] The abbreviations in the table are as follows.

[0272] B1-1: Phosphorus-containing compound (Adekastab PEP-36, manufactured by ADEKA Corporation, containing the skeleton of 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, molecular weight 633)

[0273] B1-2: Phosphorus-containing compound (Adekastab HP-10, manufactured by ADEKA Corporation, containing the skeleton of diphenyl monoalkyl phosphite, molecular weight 583)

[0274] B1-3: Phosphorus-containing compound (Adekastab 3010, manufactured by ADEKA Corporation, containing the skeleton of trialkyl phosphite, molecular weight 503)

[0275] B2-1: Phenolic hydroxyl group-containing compound (Adekastab AO-80, manufactured by ADEKA Corporation, semi-hindered type, molecular weight 741)

[0276] B2-2: Phenolic hydroxyl group-containing compound (Adekastab AO-330, manufactured by ADEKA Corporation, hindered type, molecular weight 775)

[0277] B2-3: Phenolic hydroxyl group-containing compound (IRGANOX (registered trademark) 1010, manufactured by BASF Japan Ltd., hindered type, molecular weight 1,178)

[0278] C-1: Epoxy compound (jER (registered trademark) YX8034, manufactured by Mitsubishi Chemical Corporation)

[0279] C-2: Isocyanate compound (Cosmonate (registered trademark) T100, manufactured by Mitsui Chemicals, Inc., Fine Chemicals)

[0280] C-3: Aziridine compound (Chemitite (registered trademark) PZ-33, manufactured by Nippon Catalyst Co., Ltd.)

[0281] C-4: Silane coupling agent (KBE-403, manufactured by Shin-Etsu Silicone Co., Ltd.)

[0282] F-1: Silicon dioxide (AEROSIL (registered trademark) R972, manufactured by Evonik Degussa GmbH)

[0283]

[0284]

[0285]

[0286]

[0287] In the present disclosure, in the case of a sealing sheet where the glass transition temperature (Tg) of the resin (A) is outside the range of -30°C to 40°C, as shown in Comparative Examples 1 to 2, problems with embedability were found. In addition, in the case of a sealing sheet where the thickness Ta of the resin composition layer is outside the range of 1 μm to 100 μm, as shown in Comparative Examples 3 to 4, problems with embedability and tearability were found. Furthermore, in the case where the embedding improver (B) does not contain both the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2), as shown in Comparative Examples 5 to 7, problems with light resistance, embedability, and adhesion were found.

[0288] As described in Table 5, the sealing sheets of Comparative Examples 1 to 7 cannot satisfy light resistance and embedability in a well-balanced and high-level manner. In addition, adhesion and tearability cannot be satisfied at a high level either.

[0289] In contrast, according to Examples 1 to 41, as described in Tables 2 to 5, the sealing sheets of the present disclosure exhibit excellent light resistance and also excellent embedability. Furthermore, adhesion or tearability is also excellent, and thus it was found that the sealing sheets of the present disclosure can be suitably used for sealing a plurality of light-emitting elements.

[0290] This application claims priority based on Japanese Patent Application No. 2023-079778 filed on May 15, 2023, and incorporates the entire contents disclosed therein into this application.

[0291] Explanation of Reference Numerals in the Drawings

[0292] 1: Sealing Sheet

[0293] 2: Resin Composition Layer

[0294] 3: Substrate

[0295] 4: Release Liner

[0296] 4a: First Release Liner

[0297] 4b: Second Release Liner

[0298] 5: Light-Emitting Element

[0299] 6: Substrate

[0300] 7: Glass Substrate

Claims

1. A sealing sheet for sealing a light-emitting element used in a display using a plurality of light-emitting elements as a light source, The sealing sheet comprises a resin composition layer containing a resin (A) and an embedding property improving agent (B), The resin (A) has a glass transition temperature (Tg) of -30°C to 40°C and a weight average molecular weight (Mw) of 10,000 to 1,000,000, The embedding property improving agent (B) contains a phosphorus-containing compound (B1) and a phenolic hydroxyl-containing compound (B2), The resin composition layer has a loss tangent (tan δ40) at 40° C. obtained by dynamic viscoelasticity measurement in a tensile mode at a frequency of 10 Hz and is 0.8 to 2.0, The thickness Ta of the resin composition layer is 1 μm to 100 μm.

2. The sealing sheet according to claim 1, wherein the resin (A) is a (meth)acrylic resin (a), The (meth)acrylic resin (a) is a copolymer containing a constituent unit derived from an alkyl acrylate (a1) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms and a constituent unit derived from an alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms. 3 . The sealing sheet according to claim 2 , wherein the (meth)acrylic resin (a) further contains a structural unit derived from (meth)acrylic acid (a3). 4 . The sealing sheet according to claim 1 , comprising 76% by mass to 99.9% by mass of the resin (A) based on the total mass of the resin composition layer. 5 . The sealing sheet according to claim 1 , wherein the content of the embedding property improver (B) is 0.1% by mass to 15% by mass relative to the total mass of the resin composition layer. 6 . The sealing sheet according to claim 1 , wherein a mass ratio B1:B2 of the phosphorus-containing compound (B1) to the phenolic hydroxyl group-containing compound (B2) in the embeddability improving agent (B) is 0.1:1 to 10:

1. 7 . A display comprising a sealing layer comprising the resin composition layer of the sealing sheet according to claim 1 .

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