Sealing sheet and display

Abstract

The present application provides a kind of sealing sheet even in the case of being applied to the display of multiple light emitting elements as light source, excellent light resistance, also excellent burying, and the display with sealing layer.The technical problem is solved by the following sealing sheet, the sealing sheet includes the resin composition layer containing resin (A) and burying property modifier (B), the glass transition temperature (Tg) of resin (A) is-30~40 ℃, and the weight average molecular weight (Mw) is 10,000~1,000,000, burying property modifier (B) contains phosphorus-containing compound (B1) and phenolic hydroxyl-containing compound (B2), the thickness Ta of the resin composition layer is 1 μm~100 μm, and the sealing sheet is used for the display of multiple light emitting elements as light source.

Description

[0001] This application claims priority from Japanese Application No. 2023-079778, filed May 15, 2023, the disclosure of which is incorporated herein in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to a sealing sheet, and more particularly, to a sealing sheet containing a resin composition layer for sealing a plurality of light emitting elements used in various products typified by electronic devices or displays, and a display having a sealing layer containing the resin composition layer. BACKGROUND

[0003] In recent years, with further higher performance as a goal, development of various light emitting elements is actively being conducted with respect to displays. Specifically, various display specifications such as a backlight type display using liquid crystals or quantum dots, a display using self-luminescent elements such as mini / micro Light Emitting Diodes (LEDs) or organic electroluminescence (EL), a plasma display, an electrophoretic display, and the like are being researched, and extensive use from large display applications such as signages or televisions to small size applications such as tablets, personal computers, smartphones, wearable devices, and the like are being researched. In particular, development of displays using LEDs is progressing, and a thermosetting resin composition for sealing LED elements is described in Patent Literature 1. As a next-generation display technology, the most promising is a micro LED display.

[0004] Prior Art Documents

[0005] Patent Literature

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2023-12051 SUMMARY

[0007] Problems to be Solved by the Invention

[0008] Patent Literature 1 describes a sheet-shaped resin composition for sealing light semiconductor elements that is excellent in heat resistance. However, in recent years, in LED elements that are progressing in size reduction, the interval between LED elements becomes narrower, and the sheet-shaped resin composition described in Patent Literature 1 is difficult to follow the micro-sized LED elements to fill the empty area (embeddability). In the case where there is an empty area between the LED elements and the sealing resin composition, light is refracted, and the display clarity deteriorates.

[0009] In addition, in the case of using a display outdoors, high light resistance is required. However, the conventional sealing sheet suffers from yellowing over time due to receiving sunlight, and thus there is a problem in that the image displayed by the display becomes yellow.

[0010] In order to produce a display with high clarity or less yellowing over time, a sealing sheet with excellent embeddability and light resistance is required.

[0011] The present disclosure was made in view of the problems described above, and the object thereof is to provide a sealing sheet with excellent embeddability and light resistance even when applied to a display using not only an LED element as a light source but also various light emitting elements such as organic EL, and a display having a resin composition layer.

[0012] In addition, as a further object, from the viewpoint of simplifying the manufacturing process of a micro LED display, a sealing sheet with excellent adhesion to a substrate or zipping property is provided.

[0013] Technical means for solving the problem

[0014] The present inventors made intensive studies, and as a result, found that the problems described above can be solved by a sealing sheet described below, and thus completed the present invention described in [1] to [8] below.

[0015] [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 comprising a resin composition layer containing a resin (A) having 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, and an embeddability improver (B) containing a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2), the resin composition layer having a thickness Ta of 1 μm to 100 μm.

[0016] [2] The sealing sheet according to [1], wherein the resin (A) is a (meth)acrylic resin (a),

[0017] the (meth)acrylic resin (a) is a copolymer containing a constitutional unit derived from an alkyl acrylate (a1) having a linear, branched, or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12, and a constitutional unit derived from an alkyl methacrylate (a2) having a linear, branched, or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 8.

[0018] [3] The sealing sheet according to [2], wherein the (meth)acrylic resin (a) further contains a constitutional unit derived from a (meth)acrylic acid (a3).

[0019] [4] The sealing sheet according to any one of [1] to [3], comprising 76 to 99.9 mass% of the resin (A) with respect to the total mass of the resin composition layer.

[0020] [5] The sealing sheet according to any one of [1] to [4], wherein the content rate of the embedment improver (B) is 0.1 to 15 mass% with respect to the total mass of the resin composition layer.

[0021] [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 embedment improver (B) is 0.1:1 to 10:1.

[0022] [7] The sealing sheet according to any one of [1] to [6], wherein the resin composition layer has a loss tangent at 40°C (tan δ40) of 0.8 to 2.0, obtained by dynamic viscoelasticity measurement in a tensile mode at a frequency of 10 Hz.

[0023] [8] A display having a sealing layer including a resin composition layer of the sealing sheet according to [7].

[0024] Effects of the Invention

[0025] By the present disclosure, it is possible to provide a sealing sheet excellent in embedment and light resistance even when applied to a display having a plurality of light emitting elements as light sources. In addition, by the present disclosure, it is possible to provide a sealing sheet excellent in embedment and light resistance, and adhesion or peeling properties to a substrate even when applied to a display having a micro LED element as a light source, in addition to the sealing sheet. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1A is a schematic cross-sectional view showing an example of a laminated structure of a sealing sheet.

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

[0028] Figure 1C is a schematic cross-sectional view showing another example of a laminated structure of a sealing sheet.

[0029] Figure 2 (a) to (c) of Figure 2 (c-2) of 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.

[0030] Figure 3 is a cross-sectional view showing an example of a test substrate imitating a substrate of a micro LED.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] 1: sealing sheet

[0033] 2: resin composition layer

[0034] 3: base material

[0035] 4: release liner

[0036] 4a: first release liner

[0037] 4b: second release liner

[0038] 5: light emitting element

[0039] 6: substrate

[0040] 7: glass substrate DETAILED DESCRIPTION

[0041] Hereinafter, the present disclosure is explained in detail. Furthermore, the embodiments explained below are to explain one example of the present disclosure. The present disclosure is not limited to the embodiments below, and includes modified examples implemented within the scope of the present disclosure without changing the gist of the present disclosure.

[0042] In the present specification, the numerical range designated using "~" is a range including the numerical values recited before and after "~" as lower limit values and upper limit values. (Meth)acrylic acid refers to acrylic acid and methacrylic acid. In addition, as for each component appearing in the present specification, one kind can be used alone, or two or more kinds can be used in combination, unless otherwise specifically noted.

[0043] In the present disclosure, by the weight average molecular weight (Mw) of the resin (A) being 10,000 or more and 10,000,000 or less, and the glass transition temperature (Tg) of the resin (A) being -30°C to 40°C, and the burying 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, the light resistance and the burying property can be improved. Furthermore, the close contact property and the tearability can also be improved. As for the effects, the present inventor's speculation is recited in each of the items below.

[0044] [Configuration of sealing sheet]

[0045] The sealing sheet of the present disclosure contains at least a resin composition layer. As for the sealing sheet, as shown in Figure 1A , a structure in which the resin composition layer 2 and the release liner 4 are stacked can be exemplified. In addition, as shown in Figure 1B , a structure in which the resin composition layer 2 and the base material 3 are stacked can also be exemplified. The stacked structure of the resin composition layer, and the base material or / and the release liner is not particularly limited.

[0046] As the release liner, a polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or the like; a plastic film such as polypropylene or polyethylene; or a plastic film provided with a release layer by applying a release agent such as silicone to a plastic sheet, or the like can be exemplified. The thickness of the release liner is not particularly limited, and is preferably about 10 to 200 μm.

[0047] The substrate is not particularly limited, and various optical films such as a plastic film, an anti-reflective (AR) film, a polarizing plate, a phase difference plate, or the like can be exemplified. As the plastic film, a polyvinyl chloride film, a polyethylene film, a polyethylene terephthalate (PET) film, a polyurethane film, a nylon film, a polyolefin film, a triacetyl cellulose film, a cyclic olefin film, or the like can be exemplified. The thickness of the substrate is not particularly limited, and is preferably 10 to 2000 μm. In addition, the sealing sheet of the present disclosure preferably has a three-layer structure of a substrate / resin composition layer / release liner.

[0048] As shown in FIG. 1, the sealing sheet of the present disclosure preferably has a three-layer structure of a first release liner 4a / resin composition layer 2 / second release liner 4b. Figure 1C As shown in FIG. 1, the sealing sheet of the present disclosure preferably has a three-layer structure of a first release liner 4a / resin composition layer 2 / second release liner 4b.

[0049] The first release liner and the second release liner can be arbitrarily selected, and the same release liner can be used. From the viewpoint of handling, the first release liner is preferably a light release liner, and the second release liner is preferably a heavy release liner. The thickness Tl of the light release liner is preferably in the range of 10 to 150 μm, the thickness Th of the heavy release liner is preferably in the range of 25 to 200 μm, and it is preferable to satisfy the relationship of Tl < Th. In addition, in the case where the sealing sheet is provided in a roll shape, it is preferable to provide the light release liner on the outer side of the roll.

[0050] The release force of the first release liner and the second release liner can be adjusted by the release treatment of the adhering surface of each release liner to the resin composition layer. For example, the release force can be adjusted by the kind of release agent, the coating amount of the release agent, the surface roughness of the release layer. In the case where it is desired to reduce the value of the release force, it is effective to increase the surface roughness, increase the coating amount of the release agent, or the like, and in the case where it is desired to increase the value of the release force, it is sufficient to adjust in the opposite direction. In the case where a three-layer structure as shown in FIG. 1 is adopted, it is preferable 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. Figure 1C

[0051] ​After the sealing sheet is manufactured, or while the sealing sheet is being manufactured, the sealing sheet is wound in a roll shape around a core, whereby a sealing sheet roll can be obtained. The length of the winding can be designed according to the use. From the viewpoint of improving productivity, it is preferable to be 50 m or more, and further preferable to be 100 m or more. From the viewpoint of the manufacturing yield, the length of the winding is preferably set to be 10,000 m or less.

[0052] The sealing sheet of the present disclosure is preferably used for sealing a light emitting element used in a display having a plurality of light emitting elements as light sources. The display having a plurality of light emitting elements as light sources can be exemplified by an organic EL display panel, a micro LED display panel, and the like, which require high quality.

[0053] The resin composition layer constituting the sealing sheet is preferably directly attached to and laminated with an adherend. There is no particular limitation on the adherend to be attached, and it is preferable to be an acrylic, urethane, polycarbonate, epoxy, polyimide, glass, paper, cloth, aluminum, ceramic, or polyethylene terephthalate, or the like. Further, the adherend is more preferably a substrate having an electrode portion including a metal, or a substrate having a plurality of light emitting element portions such as a backlight module, an LED, an organic EL, and the like. In addition, the substrate having a plurality of light emitting element portions can further have a light shielding layer between the light emitting element portions.

[0054] Since the resin composition layer constituting the sealing sheet has high followability to a concave-convex surface, it is suitable for a use method of filling between light emitting elements following the plurality of light emitting elements. By filling the resin composition layer between the light emitting elements, a sealing layer including the resin composition layer is formed. The sealing layer has a function of fixing the adjacent light emitting elements and preventing occurrence of peeling or deviation. In particular, the resin composition layer of the sealing sheet of the present disclosure is capable of following a light emitting element of a micro size, and thus it is more suitable for a micro LED as the light emitting element, and further preferably used as a sealing layer of a micro LED display panel.

[0055] A micro LED refers to a fine LED chip of 50 pm or 100 pm or less. By mounting a plurality of the micro LED (chip) on a substrate on which a wiring or a circuit is formed, a display having a plurality of light emitting elements as light sources is formed. The micro LED is formed of an LED element such as GaAs, GaP, AlGaInP, InGaN, a sealing resin for sealing the same, a packaging substrate, an electrode, and the like, and the operation temperature is 25°C to 60°C. Hereinafter, the micro LED will be described using Figure 2 Figure 2 An example of a procedure for forming a sealing layer will be described using (a) to (c-2) of the present disclosure.

[0056] Procedure (a): Placing procedure of sealing sheet

[0057] As described above, the sealing sheet of the present disclosure is preferably used for sealing a light emitting element used in a display having a plurality of light emitting elements as light sources. The display having a plurality of light emitting elements as light sources can be exemplified by an organic EL display panel, a micro LED display panel, and the like, which require high quality. Figure 2 ​As shown in example (a), a resin composition layer of a sealing sheet is mounted on a substrate having multiple light-emitting elements in a manner that directly covers the light-emitting elements. Furthermore, in the case where the sealing sheet has a first release liner and a second release liner, mounting is performed as described above after the first release liner is peeled off to expose the resin composition layer. The second release liner may be peeled off immediately after mounting or after the pressing process described below.

[0058] In this specification, there is no particular limitation as long as there are two or more light-emitting elements. In display applications, the number of light-emitting elements used is determined by the display size or the number of pixels.

[0059] Furthermore, there are no particular limitations on the color of light emitted by the light-emitting element; organic EL light-emitting elements and LED light-emitting elements can be used. Examples of light-emitting colors include red, green, and blue.

[0060] Regarding the size of the light-emitting element, it is preferably less than 100 μm in thickness and has an area of ​​40,000 μm when viewed from above. 2 More preferably, the thickness is 50 μm or less and the area when viewed from above is 10,000 μm. 2 The following is preferred: a thickness of 20 μm or less and an area of ​​2500 μm when viewed from above. 2 the following.

[0061] The spacing between the light-emitting elements mounted on the substrate is, for example, 10 μm to 5000 μm. When red, green, and blue light-emitting elements are grouped together and mounted as a pixel on the substrate, the spacing 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 spacing between the light-emitting elements in a pixel is, for example, 10 μm to 200 μm, preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm.

[0062] Process (b): Pressing process

[0063] like Figure 2 As shown in (b), the resin composition layer is flowed by pressing and filled around or between multiple light-emitting elements on the substrate. The resin composition layer filled around or between the multiple light-emitting elements becomes a sealing layer. The pressing method is not particularly limited, but hot pressing or vacuum pressing is preferred. From the viewpoint of the filling properties of the resin composition layer, the pressing temperature 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.

[0064] In order to improve the adhesion to the light emitting element or the adherend, heating and aging can be further performed after the 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 the heating time, the residual stress of the resin composition layer can be removed, and the adhesion surface can be smoothed. The heating and aging can also be performed after the process (c) described later.

[0065] Process (c): etching process

[0066] In the process (c), etching is performed to remove or thin the sealing layer on the light emitting element. By removing the sealing layer, the brightness of the light emitting element can be improved, and the visibility during light emission can be ensured. The thickness of the sealing layer after the etching is preferably the same as the thickness of the light emitting element as indicated in (c-1) of Figure 2 , or is less than the thickness of the light emitting element as indicated in (c-2) of Figure 2 . In addition, even if the sealing layer is not completely removed from the light emitting element, it is only necessary to be substantially removed, and it can be in a state where a thin film remains. In addition, the process (c) can be omitted when the visibility can be ensured.

[0067] The etching method is not particularly limited, and wet etching methods such as chemical polishing using a reagent, or dry etching methods such as physical polishing using a polishing material, laser etching, plasma etching using argon plasma or oxygen plasma, ion beam etching, and the like can be exemplified as preferable examples. From the viewpoint of reducing the unevenness of the surface, it is preferable to use a combination of a wet etching method and a dry etching method.

[0068] In addition, physical etching such as plasma treatment can also be used. As the etching conditions, for example, dry etching can be performed in an anisotropic plasma device using a mixed gas of CF4 / O2 / N2 at a power of 1500 W to 3000 W and a time of 180 seconds to 600 seconds. At this time, the gas supply amount of CF4 is, for example, 50 sccm to 100 sccm, the gas supply amount of O2 is, for example, 500 sccm to 1000 sccm, and the gas supply amount of N2 is, for example, 50 sccm to 100 sccm.

[0069] By the processes (a) to (c) described above, the sealing layer can be formed from the resin composition layer. Next, the constituent components of the sealing sheet of the present disclosure will be described in detail with reference to preferable examples.

[0070] [Resin composition layer]

[0071] The resin composition layer preferably contains the resin (A) and the embedment improver (B) and further contains a crosslinking agent, and can contain other components.

[0072] In the present disclosure, the resin (A) refers to a substance having a function of adhering and fixing an object to an object as an adhesive. As a specific example, a function of adhering and fixing to a substrate having a light emitting element or a plurality of light emitting elements can be cited.

[0073] The tan δ40 of the resin composition layer of the present disclosure, which is obtained by dynamic viscoelasticity measurement, is preferably 0.8 to 2.2, more preferably 1.0 to 2.0, and further preferably 1.5 to 1.9. By setting the tan δ40 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 embedment, the close contact to the adherend, and the tear resistance are improved. In the case where the tan δ40 is lower than 0.8, the diffusibility of the resin composition layer in the pressing process is too high, and thus the resin composition layer easily flows, and the end portion of the sealing layer after the pressing process can become thin. In the case where the tan δ40 is higher than 2.2, the diffusibility of the resin composition layer in the pressing process is too low, and thus the flowability of the resin composition layer deteriorates, and an empty region can be formed between the adherend and the sealing layer.

[0074] The tan δ40 is a ratio of loss elastic modulus / storage elastic modulus obtained by dynamic viscoelasticity measurement in a tensile mode at a frequency of 10 Hz and at -50°C to 150°C.

[0075] The tan δ40 can be adjusted by the kind or composition of the resin (A). In the case where the resin (A) contains the (meth)acrylic resin (a), the tan δ40 can be increased by increasing the content of the alkyl methacrylate (a2), and in the case where the tan δ40 is intended to be decreased, the adjustment can be made in the opposite direction.

[0076] In addition, the tan δ peak temperature of the tan δ of the resin composition layer of the present disclosure, which is obtained by dynamic viscoelasticity measurement, refers to the temperature at which the peak of the tan δ is the largest, and in the case where there are two or more peaks, the temperature of the peak on the lowest temperature side is indicated. The tan δ peak temperature is preferably between 0°C and 60°C, more preferably between 15°C and 55°C, and further preferably between 35°C and 45°C. By the tan δ peak temperature being between 0°C and 60°C, the molecular chain of the resin composition layer and the network structure of the embedment improver (B) can be stabilized by the heat aging process, and the residual stress of the resin can be sufficiently removed, and thus the close contact to the adherend is improved.

[0077] Further, the tan δ peak temperature of the present disclosure can be adjusted by the kind or composition of the resin (A), the kind or added amount of the crosslinking agent, the kind or added amount of the embedment improver (B), or the added amount of other components. In the case where the resin (A) contains the (meth)acrylic resin (a), the tan δ peak temperature can be increased by increasing the content of a monomer having a high glass transition temperature (Tg) of a homopolymer, and in the case where the tan δ peak temperature is desired to be decreased, the adjustment can be made in the opposite direction. The glass transition temperature (Tg) of the homopolymer in the present disclosure can use the value described in "Polymer Handbook, 1999, Fourth Edition". Specifically, as the monomer having a glass transition temperature (Tg) of 0°C or higher of a homopolymer, there can be mentioned methyl acrylate, cyclohexyl acrylate, methyl methacrylate, butyl methacrylate, and as the monomer having a glass transition temperature (Tg) of 0°C or lower of a homopolymer, there can be mentioned butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-ethylhexyl methacrylate.

[0078] Further, the peak top intensity of tan δ (tan δ peak intensity) in the range of -50°C to 80°C of the resin composition layer of the present disclosure obtained by dynamic viscoelasticity measurement refers to the value of tan δ at the time of the peak maximum of tan δ, and in the case where there are two or more peak values, the peak top intensity of the lowest side in temperature is indicated. The tan δ peak intensity is preferably 0.8 to 2.2, more preferably 1.0 to 2.0, and further preferably 1.5 to 1.9. By setting the tan δ peak intensity to 0.8 to 2.2, the absorption of the pressure applied to the resin composition layer in the pressing step becomes good, and the embedment is improved while following the light emitting element to form a uniform sealing layer.

[0079] Further, the tan δ peak intensity of the present disclosure can be adjusted by the kind or composition of the resin (A). In the case where the resin (A) contains the (meth)acrylic resin (a), the tan δ peak intensity can be decreased by increasing the content of the alkyl acrylate (al), and in the case where the tan δ peak intensity is desired to be increased, the adjustment can be made in the opposite direction.

[0080] The dynamic viscoelasticity in the present disclosure and the loss tangent (tan δ) are measured by the method described in the Examples described later. Further, in the case where the resin composition layer contains a crosslinking agent, the crosslinking reaction based on heating is in an incomplete state at the time of measurement.

[0081] The thickness Ta of the resin composition layer is preferably 1 μm to 100 μm, more preferably 3 μm to 50 μm, and even more preferably 5 μm to 35 μm in terms of embeddability and tearability. By setting the thickness Ta of the resin composition layer to 1 μm or more, stress at the time of peeling off the release liner is efficiently dispersed, and sufficient tearability is exerted. In addition, pressure in the pressing step is diffused in the resin composition layer, and sufficient embeddability is exerted. In the case where the thickness Ta of the resin composition layer is 100 μm or less, pressure absorbed by the resin composition layer is less in relation to pressure applied in the pressing step, and the resin composition layer sufficiently flows, and thus excellent embeddability is exerted. In addition, stress applied to the resin composition layer at the time of peeling off the release liner is not easily shifted, and thus excellent tearability is exerted.

[0082] In the case where the thickness Ta of the resin composition layer is less than 1 μm, pressure is not completely diffused in the resin composition layer at the time of flowing of the resin composition layer in the pressing step, and shift is easily generated, and embeddability becomes poor. In addition, stress applied to the resin composition layer at the time of peeling off the release liner is not completely diffused, and tearability becomes poor. In the case where the thickness Ta of the resin composition layer is more than 100 μm, the end portion of the resin composition layer easily flows at the time of flowing of the resin composition layer in the pressing step, the thickness of the resin composition layer becomes uneven, a difference in applied pressure is generated, and thus embeddability becomes poor. In addition, since aggregation in the resin composition layer is easily broken, tearability becomes poor. The resin composition layer can be a single layer, or can be a laminated layer of two or more layers. The thickness Ta in the present disclosure is measured by the method described in the Examples below.

[0083] [Method for forming resin composition layer]

[0084] The method for forming the resin composition layer is not particularly limited, and as a suitable example, a method in which a resin composition obtained by adding an arbitrary solvent to components constituting the resin composition layer is applied to form the resin composition layer can be cited. The purpose of adding the solvent is to adjust the viscosity level to be suitable for application.

[0085] A known applicator or method such as a doctor blade coater, a die coater, a roll coater, a lip die coater, a reverse coater, a gravure coater, a bar coater, a curtain coater, dip coating, spin coating, screen, casting, and the like can be used at the time of application. The solvent contained in the resin composition can be removed by a drying step after application.

[0086] As a preferred embodiment, the resin composition can be applied to a support such as a release liner or a substrate, and then the applied film is heated and dried using a hot air oven, an infrared heater, or the like, thereby forming a resin composition layer on one side of the support. Furthermore, 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 under specific temperature conditions, or irradiation of ultraviolet (UV) rays, or the like.

[0087] [Resin composition]

[0088] The resin composition can be obtained by stirring and mixing a solvent, the resin (A), and the embedment improver (B). Any solvent is used for the purpose of adjusting the viscosity or the like for the processability when the resin (A) and the embedment improver (B) are mixed, and thus a solvent that is compatible with the resin (A), such as an ester-based, ether ester-based, ether-based, alcohol-based, aromatic-based, or the like, can be appropriately used. Specifically, acetone, 2-butanone, ethyl acetate, cyclohexanone, toluene, xylene, isopropyl alcohol, N-methyl-2-pyrrolidone, or the like can be exemplified as appropriate examples. The stirring can use a known stirring device, and a disperser, a mixer, a shaker, a homogenizer, or the like is preferable.

[0089] In order to obtain the resin composition, a two-stage or more manufacturing process in which, first, a mixture of the resin (A) or any solvent mixed with the embedment improver (B) is prepared, and, second, the resin (A), the crosslinking agent, and other components are added as necessary can be employed.

[0090] [Resin (A)]

[0091] The resin (A) can use any one of a thermally curable resin, a light curable resin, a thermoplastic resin, and can use a single one, or two or more can be used in combination. From the viewpoint of embedment, it is preferable to contain at least one or more thermally curable resins. The thermally curable resin is a resin having a plurality of functional groups that can be used in a crosslinking reaction based on heating, and can also have a functional group that can self-crosslink. The resin can also contain a thermally curable monomer, but in the present embodiment, from the viewpoint of the strength of the coating film, it is preferable to use a thermally curable resin having a weight average molecular weight (Mw) of 10,000 or more.

[0092] Suitable examples of the thermosetting resin can include: (meth)acrylic resin (a), maleic acid resin, polybutadiene resin, polyester resin, condensation type polyester resin, addition type polyester resin, melamine resin, urethane resin or urethane urea resin, epoxy resin, polycarbonate resin, oxetane resin, phenoxy resin, polyimide resin, polyamide imide resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluorine resin, and the like. From the viewpoint of embeddability, at least one of (meth)acrylic resin (a), epoxy resin, urethane resin, polycarbonate resin, and polyamide resin is preferably included. Further, from the viewpoint of adhesiveness and tear resistance to the adherend, (meth)acrylic resin (a) is more preferably included. In addition, from the viewpoint of light resistance, (meth)acrylic resin (a) having high transparency and less likely to be oxidatively deteriorated is particularly preferably included.

[0093] The functional group of the thermosetting resin can be appropriately selected depending on the combination with the crosslinking agent described later, and examples thereof can include: hydroxyl group, carboxyl group, amino group, epoxy group, oxetane group, oxazoline group, oxazine group, aziridine group, thiol group, isocyanate group, blocked isocyanate group, silanol group, and the like. From the viewpoint of the compatibility of the embeddability improver (B), carboxyl group, hydroxyl group, and epoxy group are preferred. In the case of having a carboxyl group, the acid value of the thermosetting resin is preferably 1 mgKOH / g or more and 50 mgKOH / g or less, more preferably 3 mgKOH / g or more and 30 mgKOH / g or less, and further preferably 5 mgKOH / g or more and 20 mgKOH / g or less.

[0094] By setting the acid value of the thermosetting resin to 1 mgKOH / g or more, the intermolecular force with the adherend is favorably maintained while the crosslinking density with the crosslinking agent is optimized, and the light resistance, adhesiveness, and tear resistance become favorable. By setting the acid value of the thermosetting resin to 50 mgKOH / g or less, the intermolecular force with the adherend is favorably maintained, and the residual amount of carboxyl group, which accelerates yellowing of the resin after the crosslinking reaction, is appropriately adjusted, and thus the light resistance, adhesiveness, and tear resistance become favorable. The acid value in the present disclosure is measured by the method described in the Examples described later.

[0095] In the present disclosure, the urethane resin refers to a general term for a compound including two or more urethane bonds in one molecule. The urethane resin can be obtained by reacting a polyisocyanate with a polyol.

[0096] The polyisocyanate can be any substance having two or more isocyanate groups in one molecule, and is preferably a diisocyanate or a triisocyanate, and more preferably a diisocyanate, in terms of the compatibility of the embedding property improving agent (B). As the diisocyanate, a known aliphatic diisocyanate such as hexamethylene diisocyanate, or a known aromatic diisocyanate such as phenyl-1,3-diisocyanate can be appropriately selected and used. In addition, an isocyanate group terminal prepolymer obtained by reacting a polyol with an excess of a polyisocyanate can also be used as an intermediate of the urethane resin.

[0097] The polyol can be any substance having two or more hydroxyl groups in one molecule, and is preferably a diol or a triol, and more preferably a diol, in terms of the compatibility of the embedding property improving agent (B). As the diol, a known aliphatic diol such as ethylene glycol, or a known aromatic diol such as phenyleneglycol can be appropriately selected and used. In addition, a prepolymer such as a polyether polyol, a polyester polyol, or a polycarbonate polyol can also be used.

[0098] The urethane resin can also 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.

[0099] The polyamine can be any substance having two or more amino groups in one molecule, and is preferably a diamine or a triamine, and more preferably a diamine, in terms of the compatibility of the embedding property improving agent (B). As the diamine, a known aliphatic diamine such as ethylenediamine, or a known aromatic diamine such as phenylenediamine can be appropriately selected and used.

[0100] The photohardenable resin can be any resin having one or more unsaturated bonds that undergo crosslinking reactions by light in one molecule. As appropriate examples of the photohardenable resin, for example, acrylic resins, maleic acid resins, polybutadiene resins, polyester resins, polyurethane resins, epoxy resins, oxetane resins, phenoxy resins, polyimide resins, polyamide resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluorine resins, etc. can be listed. In addition, the photohardenable resin can also have a functional group that can be utilized in crosslinking reactions based on heating.

[0101] In the case where the resin composition layer contains a photohardenable resin, an initiator is preferably also contained. As the initiator, a triazine-based photopolymerization initiator, a borate-based photopolymerization initiator, a carbazole-based photopolymerization initiator, a phenylethanone-based photopolymerization initiator, and an oxime ester-based photopolymerization initiator, etc. can be used.

[0102] Among these, the phenylethanone-based photopolymerization initiator and the oxime ester-based photopolymerization initiator are preferred because yellowing is less during the heat aging step.

[0103] The content of the initiator is preferably 0.5 to 10 mass% and more preferably 0.5 to 5 mass% based on the total amount (100 mass%) of the resin composition layer in terms of yellowing.

[0104] Examples of the thermoplastic resin include a butyral resin, a styrene-maleic acid copolymer, a chlorinated polyethylene, a chlorinated polypropylene, a polyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, a polyvinyl acetate, a polyester resin, a vinyl-based resin, an alkyd resin, a polystyrene resin, a polyamide resin, a rubber-based resin, a ringed rubber-based resin, a cellulose, a polyethylene (high density polyethylene (HDPE), low density polyethylene (LDPE)), a polybutadiene, and a polyimide resin.

[0105] The weight average molecular weight (Mw) of the resin (A) is 10,000 to 1,000,000. In terms 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, and therefore the entanglement of the molecular chain in the heat aging step becomes extremely easy to unravel, and is most preferably optimized, whereby the followability to the adherend is appropriate, and therefore the adhesion can be improved. By setting the Mw to 1,000,000 or less, the compatibility with the embedment improver (B) becomes good, the influence of yellowing due to oxidative degradation caused by light irradiation can be prevented, and the light resistance is improved.

[0106] In addition, the ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) that represents 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 the Mw / Mn to 1 to 5, the flow rate at the time of heating the resin is homogenized in the resin, and therefore the flowability of the resin is easily controlled, and the embedment is improved. In addition, since the speed of wetting the adherend is also homogenized, the adhesion is improved.

[0107] Further, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values converted to polystyrene measured by a 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 method described in the Examples below.

[0108] The glass transition temperature (Tg) of the resin (A) is -30°C to 40°C. From the viewpoint of light resistance, embedding property, and adhesion, it is more preferably -20°C to 30°C, further preferably -10°C to 25°C, further more 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 flowability or wettability of the resin (A) in the pressing step is appropriate, and the embedding property or adhesion is improved. In addition, in the heat aging step, a network structure of the resin (A) and the embedding improver (B) is easily formed, and the light resistance is improved.

[0109] By setting the glass transition temperature (Tg) to 40°C or lower, when pressure is applied to the resin composition layer in the pressing step, the molecular motion of the resin (A) contained in the resin composition layer is activated, and the entanglement of the molecular chains easily becomes loose. If the entanglement of the molecular chains is loose, the resin (A) can be deformed in a manner following the unevenness of the substrate or the light emitting element, and the like, the empty space between the light emitting element and the resin composition layer can be reduced, and the embedding property is improved. In addition, the compatibility with the embedding improver (B) becomes good, the influence of yellowing due to oxidative deterioration by light is prevented, and the light resistance is improved. Further, the entanglement of the molecular chains of the resin composition layer and the coordination with the embedding improver (B) are most preferably optimized in the heat aging, the residual stress is removed, and thus the sealing layer is smoothed, and the adhesion to the adherend is improved.

[0110] In the case where the glass transition temperature (Tg) is lower than -30°C, the flowability of the resin (A) in the pressing step is too high, and thus the thickness of the sealing layer is not uniformized, the resin flows at the end portion of the sealing layer and is thinned, the function of fixing the light emitting element is not exhibited, the adhesion is deteriorated, and the embedding property becomes poor. In addition, in the heat aging step, a network structure of the resin (A) and the embedding improver (B) is not easily formed, and thus the light resistance is deteriorated.

[0111] In the case where the glass transition temperature (Tg) is higher than 40°C, the flowability of the resin (A) is low, and the resin (A) is difficult to follow the unevenness of the light emitting element, and the embedding property becomes poor. In addition, since the wettability to the adherend is low, the adhesion is deteriorated, the compatibility of the embedding improver (B) and the resin (A) is destabilized, and thus the light resistance becomes poor.

[0112] In the case where the resin (A) contains a thermally curable resin or a photo-curable resin, the glass transition temperature (Tg) of the resin (A) indicates the glass transition temperature (Tg) before thermal curing and before photo-curing. The glass transition temperature (Tg) of the resin (A) in the present disclosure is measured by the method described in the Examples described later.

[0113] The content of the resin (A) is preferably 76 to 99.9 mass%, more preferably 81 to 99 mass%, and further preferably 86 to 95 mass%, based on the total amount (100 mass%) of the resin composition layer. In the case where two or more kinds of the resin (A) are contained, the content of any one of the resin (A) is preferably 10 mass% or more, and the total content is preferably within the above range. By setting the content of the resin (A) to 76 to 99.9 mass%, the light resistance, embeddability, adhesion, and tear resistance become good. In the case where the content of the resin (A) is less than 76 mass%, the network structure of the resin (A) and the embedment improver (B) is not easily optimized, and thus the light resistance deteriorates. In addition, since the embedment improver (B) does not easily function in the pressing step, the embeddability deteriorates, the intermolecular force derived from the resin (A) becomes weak, and thus the adhesion or tear resistance deteriorates.

[0114] [(METH) ACRYLATE RESIN (A)]

[0115] In the present disclosure, the (meth)acrylate resin (a) is preferably an acrylic copolymer obtained by copolymerizing a (meth)acrylate monomer. As a suitable example of the (meth)acrylate monomer, an alkyl (meth)acrylate monomer can be exemplified. In the case where a crosslinked structure is formed, a (meth)acrylic copolymer obtained by copolymerizing a functional group-containing monomer and a (meth)acrylate monomer is preferred.

[0116] The (meth)acrylic acid alkyl ester monomer is a compound in which (meth)acrylic acid is esterified and an alkyl group or a cycloalkyl group is introduced, and the alkyl group or the 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 a carbon number of 1 to 20, and more preferably a saturated aliphatic hydrocarbon group having a carbon number of 1 to 12. As specific examples, mention can be made of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, amyl (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, and the like. Among these, from the viewpoint of compatibility with the embedding property modifier (B), it is particularly preferable to use methyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate.

[0117] The structural unit derived from the (meth)acrylic acid alkyl ester monomer is preferably 1 to 100 mass%, more preferably 20 to 99.9 mass%, and further preferably 80 to 99.7 mass%, relative to 100 mass% of the (meth)acrylic acid resin (a).

[0118] The (meth)acrylic acid resin (a) preferably has a functional group-containing monomer. As the functional group-containing monomer, mention can be made of 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 cohesive force of the resin (A) is increased, and a strong and tough resin composition layer can be obtained.

[0119] As the carboxyl group-containing monomer, mention can be made of, for example, (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 isocitraconic acid. Among these, from the viewpoint of adhesiveness, (meth)acrylic acid is particularly preferable.

[0120] As the hydroxyl group-containing monomer, for example, 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 can be exemplified. Of these, from the viewpoint of adhesiveness, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate are more preferable.

[0121] As the epoxy group-containing monomer, for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate can be exemplified.

[0122] As the amino group-containing monomer, for example, monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, and other monoalkylamino (meth)acrylates can be exemplified.

[0123] The total of the constitutional units derived from the functional group-containing monomers is preferably 0.1 to 20 mass% relative to 100 mass% of the (meth)acrylic resin (a). By being in the range, the cohesiveness can be adjusted by the reaction with the crosslinking agent.

[0124] The constitutional unit derived from the carboxyl group-containing monomer is preferably 0.1 to 10 mass% relative to 100 mass% of the (meth)acrylic resin (a). By being in the range, the adhesiveness to the adherend can be improved.

[0125] In addition, the constitutional unit derived from the hydroxyl group-containing monomer is preferably 0.1 to 10 mass% relative to 100 mass% of the (meth)acrylic resin (a). By being in the range, the adhesiveness to the adherend can be adjusted.

[0126] The (meth)acrylic resin (a) can also contain a constitutional unit derived from other monomers copolymerizable with the alkyl (meth)acrylate and the functional group-containing monomer. For example, monomers having an alkyleneoxy group, other vinyl monomers can be exemplified. For example, methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, acrylamide can be exemplified. The constitutional unit derived from the other monomers is preferably 0.1 to 20 mass% relative to 100 mass% of the (meth)acrylic copolymer.

[0127] As a more preferable example of the (meth)acrylic resin (a), a (meth)acrylic copolymer containing one or more constitutional units derived from an alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12, and one or more constitutional units derived from an alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 8 can be exemplified.

[0128] By containing one or more constitutional units derived from an alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12, interaction with the interface of the adherend in a short contact time is easily exhibited, the gap between the light emitting element and the resin composition layer at the time of embedding can be reduced, and embedding property is improved.

[0129] By the (meth)acrylic resin (a) containing one or more constitutional units derived from an alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 8, wetting expansion to the interface of the adherend in a long contact time is easily exhibited, the gap between the light emitting element and the resin composition layer at the time of embedding can be reduced, and embedding property is improved.

[0130] From the viewpoint of optimizing the interaction with the interface of the adherend in a short contact time and improving embedding property and close contact property, the alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12 is preferably an alkyl acrylate having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 8, and more preferably an alkyl acrylate having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 4. In addition, the saturated aliphatic hydrocarbon group of the alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12 is more preferably a linear or branched chain.

[0131] From the viewpoint of improving embedding property and close contact property, the total mass of the constitutional units derived from the alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12 is preferably 1 to 95 mass%, more preferably 5 to 70 mass%, and further preferably 7 to 60 mass%, relative to 100 mass% of the (meth)acrylic resin (a).

[0132] From the viewpoint of optimizing the wetting spread to the adherend interface over a long contact time, improving the embedding property and the close contact property, the methacrylic acid alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms is preferably a methacrylic acid alkyl ester having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 4 carbon atoms. Further, the saturated aliphatic hydrocarbon group of the methacrylic acid alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms is more preferably a linear or branched chain.

[0133] From the viewpoint of improving the embedding property and the close contact property, the total mass of the structural units derived from the methacrylic acid alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, relative to 100 mass% of the (meth)acrylic acid resin (a) is preferably 1 mass% to 95 mass%, more preferably 30 mass% to 90 mass%, and further preferably 35 mass% to 85 mass%.

[0134] The ratio of the total mass of the structural units derived from the acrylic acid alkyl ester (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, to the total mass of the structural units derived from the methacrylic acid alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, in the (meth)acrylic acid resin (a) is preferably 1 : 0.4 to 1 : 20, more preferably 1 : 0.6 to 1 : 15, and further preferably 1 : 1 to 1 : 13, and particularly preferably 1 : 5 to 1 : 9.

[0135] By being 1 : 0.4 to 1 : 20, the light resistance can be improved, the intramolecular interaction of the (meth)acrylic acid resin (a) is adapted, and the flowability of a resin in which the embedding property is good is exhibited. Further, the wetting property of the (meth)acrylic acid resin (a) to the adherend is optimized, and the close contact property is good.

[0136] As a more preferable example of the (meth)acrylic acid resin (a), a (meth)acrylic acid copolymer containing one or more constitutional units derived from a (meth)acrylic acid (a3), in addition to the constitutional unit derived from the acrylic acid alkyl ester (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, and the constitutional unit derived from the methacrylic acid alkyl ester (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, can be cited.

[0137] The total amount of structural units derived from the (meth)acrylic acid (a3) is preferably 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, and further preferably 0.5 to 5% by mass, relative to 100% by mass of the (meth)acrylic resin (a). By setting the amount to 0.1 to 15% by mass, the adhesion can be improved by intermolecular interaction with the adherend. In addition, from the viewpoint of improving the adhesion to the adherend, the (meth)acrylic acid (a3) is more preferably methacrylic acid.

[0138] As a further preferred example of the functional group-containing monomer constituting the (meth)acrylic resin (a), an example in which neither the (meth)acrylic acid (a3) nor the hydroxyl group-containing monomer is contained can be given. By containing neither the (meth)acrylic acid (a3) nor the hydroxyl group-containing monomer, the cohesion of the (meth)acrylic resin (a) can be adjusted, and the adhesion can be improved.

[0139] The (meth)acrylic resin (a) can be obtained by polymerizing an acrylic monomer mixture. At the time of 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 relative to 100% by mass of the monomer mixture. The polymerization method is not limited. For example, the polymerization can be performed by solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization, and the solution polymerization is particularly preferred in terms of the ease of polymerization control. The solvent used in the solution polymerization can be exemplified by, for example, acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, and cyclohexanone. The polymerization temperature can be set to, for example, about 60 to 120°C, and the polymerization time can be set to about 2 to 12 hours.

[0140] The polymerization initiator is preferably a radical polymerization initiator. As the radical polymerization initiator, peroxides and azo compounds are suitable. The azo compounds can be exemplified by 2,2'-azobisisobutyronitrile (abbreviated as: AIBN (2,2'-azobisisobutyronitrile)), 2,2'-azobis(2-methylbutyronitrile), and the like 2,2'-azobisbutyronitriles; 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and the like 2,2'-azobispentanenitriles; 2,2'-azobis(2-hydroxymethylpropionitrile), and the like 2,2'-azobispropionitriles; 1,1'-azobis(cyclohexane-1-carbonitrile), and the like 1,1'-azobis-1-alkanenitriles. The peroxides can be exemplified by di-tert-butyl peroxide, diisopropylbenzene peroxide, tert-butyl cumyl peroxide, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-di(tert-butylperoxy)hexyne-3, and the like dialkyl peroxides; tert-butyl peroxybenzoate, tert-butyl peroxyacetate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and the like peroxy esters; cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, and the like 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 the like peroxyketal; cumyl hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide, and the like hydroperoxides; benzoyl peroxide, decanoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, and the like diacyl peroxides; bis(tert-butylcyclohexyl) peroxydicarbonate, and the like peroxydicarbonates.

[0141] [Embedding improver (B)]

[0142] In the present embodiment, the embedding improver (B) is a compound having a function of improving the flowability of the resin (A) and improving the embedding property into the plurality of light emitting elements, and contains a phosphorus-containing compound (B1) and a phenolic hydroxyl group-containing compound (B2). By containing both the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2) in the resin composition layer, the embedding property is improved. In addition, it also has the effect of improving light resistance, adhesion, and tear resistance.

[0143] The present inventors conceived the following mechanism. First, in the press process, the embedding property improver (B) moves freely into the intermolecular chains of the resin (A) sufficiently, thereby cutting the intermolecular interaction of the resin (A), assisting uniform disentangling of the resin (A), thereby increasing the fluidity, and the resin composition layer deforms in a manner following the light emitting element. Thereafter, the phosphorus atom sites of the phosphorus-containing compound (B1) are weakly coordinated to the phenolic hydroxyl sites of the phenolic hydroxyl-containing compound (B2), while entering the molecular chains of the resin (A) having the weight average molecular weight (Mw) defined in the present disclosure, thereby forming a uniform network structure, further deformation of the resin composition layer is suppressed, and the embedding property is improved. 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-containing compound (B2) have a radical trapping function, and the resin (A) and the embedding property improver (B) form a uniform network structure, thereby the radical trapping function is efficiently exhibited, and the light resistance is improved. In addition, since the intermolecular interaction of the adherend and the resin (A) is moderately adjusted, the adhesion is improved. Furthermore, since the stress applied when the release liner is peeled off is uniformly dispersed, the peeling property is improved.

[0144] The mass ratio B1:B2 of the phosphorus-containing compound (B1) and the phenolic hydroxyl-containing compound (B2) in the embedding property improver (B) is preferably 0.1:1 to 10:1, more preferably 0.5:1 to 5:1, and further preferably 1:1 to 3:1. By being 0.1:1 to 10:1, the molecular chains of the resin (A) and the embedding property improver (B) form a uniform network structure, and the embedding property is improved. In addition, since the radical trapping function of the embedding property improver (B) can be sufficiently exerted, the light resistance is excellent. Furthermore, the coordination of the phosphorus-containing compound (B1) and the phenolic hydroxyl-containing compound (B2) becomes appropriate, and the coagulation properties of the resin (A) are not hindered, and thus the peeling property becomes good.

[0145] From the viewpoint of the embedding property and the adhesion, the content ratio of the embedding property improver (B) in the total amount (100 mass%) of the resin composition layer is preferably 0.1 mass% to 15 mass%, more preferably 0.3 mass% to 10 mass%, and further preferably 0.5 mass% to 5 mass%. By being 0.1 mass% to 15 mass%, the embedding property, the adhesion, the light resistance, and the peeling property are improved.

[0146] [Phosphorus-containing compound (B1)]

[0147] As the phosphorus-containing compound (B1) used in the present disclosure, there is no particular limitation as long as it is a compound containing phosphorus in the molecule, and 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 further preferably a compound having a molecular weight of 30 to 2,000. The phosphorus-containing compound (B1) can be used alone or in combination with two or more. From the viewpoint of compatibility or embeddability, it is preferable to use one or more of a substance that is solid at normal temperature and one or more of a substance that is liquid.

[0148] As the phosphorus-containing compound (B1), it is possible to use, for example, tris(2- ethylhexyl)phosphite, tridecylphosphite, trilaurylphosphite, tris(tridecyl)phosphite, tristearylphosphite, phenylisooctylphosphite, phenylisodecylphosphite, phenyl di(tridecyl)phosphite, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyltridecylphosphite, triphenylphosphite, tricresylphosphite, tris(nonylphenyl)phosphite, 4,4'-isopropylidenebisphenylalkylphosphite, trinonylphenylphosphite, tri-dinonylphenylphosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(diphenyl)phosphite, bis(decyl) pentaerythritol diphosphite (alias: 3,9-bis(decyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), bis(tridecyl) pentaerythritol diphosphite (alias: 3,9-bis(tridecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), distearyl pentaerythritol diphosphite (alias: 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), di(nonylphenyl) pentaerythritol diphosphite (alias: 3,9-bis(nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), di(2,4-di-t-butylphenyl) pentaerythritol diphosphite (alias: 3,9-bis(2,4-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), di(2,6-di-t-butylphenyl) pentaerythritol diphosphite (alias: 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane), phenyl bisphenol A pentaerythritol diphosphite, tetra-tridecyl 4,4'-butylidenebis(3-methyl-6-t-butylphenol) diphosphite, hexa-tridecyl 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane triphosphite, 3,5-di-t-butyl-4-hydroxybenzylphosphite diethyl ester, sodium bis(4-t-butylphenyl)phosphite, sodium 2,2-methylene-bis(4,6-di-t-butylphenyl)phosphite, 1,3-bis(diphenyloxyphosphoryloxy)-benzene, ethyl bis(2,4-di-t-butyl-6-methylphenyl)phosphite, and the like. In addition, other oligomer type compounds having a phosphite structure and having a molecular weight of less than 10,000 can also be used.

[0149] In particular, from the viewpoint of light resistance and embeddability, a compound having a skeleton of triphenyl phosphite, a compound having a skeleton of trialkyl phosphite, a compound having a skeleton of diphenyl monoalkyl phosphite, a compound having a skeleton of monophenyl dialkyl phosphite, and a compound having a skeleton of 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane are preferred. In addition, the phenyl skeleton can also have a substituent such as a t-butyl group.

[0150] Further, specifically, tris(2,4-di-t-butylphenyl) phosphite, tris(2-ethylhexyl) phosphite, bis(decyl) pentaerythritol diphosphite, bis(tridecyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, di(2,4-di-t-butylphenyl) pentaerythritol diphosphite, di(2,6-di-t-butylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite are more preferred, and distearyl pentaerythritol diphosphite and di(2,6-di-t-butylphenyl) pentaerythritol diphosphite are further preferred.

[0151] 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 Co., Ltd.; "IRGAFOS (registered trademark) 168, 168FF, 38, 126, P-EPQ, 12" manufactured by BASF Japan 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 Teikoku Chemical Industry Co., Ltd.; "Everaox (registered trademark) 168, 201, 202, 203, 204" manufactured by Everlight Chemical Materials Japan Ltd.; "Hostanox (registered trademark) P-EPQ (registered trademark)" manufactured by Clariant Co., Ltd.; and "Ultranox (registered trademark) 626" manufactured by FUJIFILM Wako Pure Chemical Corporation.

[0152] The content ratio of the phosphorus-containing compound (B1) with respect to the total amount (100 mass%) of the resin composition layer is preferably 0.05 to 10 mass%, more preferably 0.2 to 7 mass%, and further preferably 0.4 to 6 mass%.

[0153] [Phenolic hydroxyl group-containing compound (B2)]

[0154] The phenolic hydroxyl group-containing compound (B2) used in the present disclosure is a compound containing a phenolic hydroxyl group in the molecule and not containing phosphorus. The molecular weight is preferably less than 10,000, more preferably 94 to 5,000, and further preferably 94 to 3,000. The phenolic hydroxyl group-containing compound (B2) can be used alone or in combination with two or more.

[0155] As the compound (B2) containing a phenolic hydroxyl group, 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 tetrakis[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-hydroxyphenylpropionamide), 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, bis[[3,5-di(tert-butyl)-4-hydroxybenzyl]phosphonic acid ethyl]calcium, 2,4-bis(octylthiomethyl)-6-methylphenol, bis(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate ethylene bis(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-triazinane-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-methylpropane-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 tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-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, and the like can be used.

[0156] In particular, from the viewpoint of light resistance or embeddability, a phenolic hydroxyl group-containing compound having a skeleton of a hindered structure in which two tert-butyl groups are bonded to the ortho positions of the phenolic hydroxyl group, a skeleton of a semi-hindered structure 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, and further, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-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 are preferred.

[0157] 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 Co., Ltd.; "KEMINOX 9425, 179" manufactured by Chemipro Industry Co., Ltd.; "SUMILIZER (registered trademark) GA-80, GM, GS, GA-80, MDP-S, WX-R, WX-RC, BBM-S" manufactured by Sumitomo Chemical Co., Ltd.; "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 Co., Ltd.

[0158] The content ratio of the phenolic hydroxyl group-containing compound (B2) with respect to the total amount (100 mass%) of the resin composition layer is preferably 0.04 mass% to 5 mass%, more preferably 0.1 mass% to 3.5 mass%, and further preferably 0.2 mass% to 3 mass%.

[0159] [Crosslinking agent]

[0160] The resin composition layer of the present disclosure can also contain a crosslinking agent. In particular, in the case where the resin (A) comprises a thermally curable resin, it is preferable to use a crosslinking agent in order to promote the formation of a crosslinked structure. The crosslinking agent can be used alone or in combination with two or more. The crosslinking agent reacts with the reactive functional groups of the resin (A) during the heat pressing or heat aging in the pressing step, thereby making the adhesion to the adherend such as a light emitting element more robust. In addition, the cohesion of the resin composition layer can be improved, and thus the tear resistance becomes good.

[0161] The crosslinking agent has a plurality of functional groups capable of reacting with the functional groups of the resin (A). The crosslinking agent can be exemplified by known compounds such as silane coupling agents, epoxy compounds, anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, amine compounds, and the like. From the viewpoint of adjusting the loss tangent (tan δ) of the resin composition layer, it is preferable to use a silane coupling agent, an epoxy compound, an aziridine compound, an imidazole compound, an isocyanate compound, and more preferable to use an epoxy compound.

[0162] The epoxy compound is a compound having two or more epoxy groups in one molecule. As the properties of the epoxy compound, by using a liquid, the tan δ peak temperature of the resin composition layer can be lowered, and the light emitting element and the resin composition layer can be well adhered. On the other hand, by using a solid epoxy compound, the tan δ peak temperature of the resin composition layer can be increased, and the tackiness of the resin composition layer can be controlled, and the tear resistance can be adjusted.

[0163] As the epoxy compound, for example, a glycidyl ether type epoxy compound, a glycidyl amine type epoxy compound, a glycidyl ester type epoxy compound, a cyclic aliphatic (alicyclic type) epoxy compound is preferable. In addition, from the viewpoint of light resistance, the epoxy compound is more preferably a high purity hydrogenated epoxy resin.

[0164] As the glycidyl ether type epoxy compound, for example, a cresol novolac type epoxy compound, tris(glycidyloxyphenyl)methane, tetra(glycidyloxyphenyl)ethane can be exemplified. As the glycidyl amine type epoxy compound, for example, tetraglycidyl diaminodiphenylmethane, tetraglycidyl m-xylylenediamine can be exemplified.

[0165] As the glycidyl ester type epoxy compound, for example, diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, and the like can be exemplified.

[0166] As the cyclic aliphatic (alicyclic type) epoxy compound, for example, epoxycyclohexylmethyl-epoxycyclohexane carboxylate, bis(epoxycyclohexyl)adipate, and the like can be exemplified.

[0167] As the aziridine compound, for example, trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(l-aziridinylcarboxyamide), N,N'-hexamethylene-l,6-bis(l-aziridinylcarboxyamide), tris-2,4,6-(l-aziridinyl)-l,3,5-triazine, 4,4'-bis(ethyleneiminylcarbonylamino)diphenylmethane, and the like can be exemplified.

[0168] As the imidazole compound, for example, 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 isocyanuric acid adduct, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like can be exemplified, and further, a compound in which an imidazole compound is reacted with an epoxy resin to be insoluble in a solvent, or a compound in which an imidazole compound is encapsulated in a microcapsule, and the like, which have improved storage stability, can be exemplified.

[0169] The isocyanate compound is an isocyanate having two or more isocyanate groups. The isocyanate compound is, for example, preferably an aromatic polyisocyanate, an aliphatic polyisocyanate, an aromatic-aliphatic polyisocyanate, an alicyclic polyisocyanate, and the like, and a biuret, a nurate, and an adduct of these isocyanate monomers.

[0170] The aromatic polyisocyanate is, for example, 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, and the like.

[0171] The aliphatic polyisocyanate can be exemplified by 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.

[0172] The aromatic aliphatic polyisocyanate can be exemplified by 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.

[0173] The alicyclic polyisocyanate can be exemplified by 3-isocyanatemethyl-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(isocyanatemethyl)cyclohexane.

[0174] The biuret body is a self-condensate having a biuret bond, which is formed by self-condensation of an isocyanate monomer. The biuret body can be exemplified by a biuret body of hexamethylene diisocyanate.

[0175] The uretonimine body is a trimer of an isocyanate monomer. It can be exemplified by a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimer of toluene diisocyanate, and the like.

[0176] The adduct is a di- or higher functional isocyanate compound, which is formed by reacting an isocyanate monomer with a di- or higher functional compound containing a low molecular active hydrogen. The adduct can be exemplified by 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.

[0177] The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct that is a reaction product of an isocyanate monomer and a trifunctional low-molecular active hydrogen-containing compound, and a uretonimine. The isocyanate compound is preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a uretonimine of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, a uretonimine of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, a uretonimine of isophorone diisocyanate, and more preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate.

[0178] In the present disclosure, two or more crosslinking agents are preferably contained from the viewpoint of the scratch resistance of the coating film. From the viewpoint of adjusting the loss tangent (tan δ) of the resin composition layer, specifically, examples in which two or more are contained from among a silane coupling agent, an epoxy compound, an aziridine compound, and an isocyanate compound can be cited, and further, examples in which one or more of a silane coupling agent, an epoxy compound, an aziridine compound, and an isocyanate compound, and an epoxy compound different in kind from the aforementioned epoxy compound are used together can be cited.

[0179] The content ratio of the crosslinking agent (the total content ratio in the case of using two or more) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and further preferably 0.1 to 10% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content ratio to the aforementioned range (0.01 to 30% by mass), the compatibility and embeddability of the embedment property improver (B) can be appropriately adjusted.

[0180] [Other Components]

[0181] Other components can also be contained in the resin composition layer of the present disclosure, within a range that does not impair the object of the present disclosure. For example, an inorganic filler, a colorant, a dispersant, a surface adjusting additive, a hardening accelerator, a hardening retarder, a softening agent, an antistatic agent, a lubricant, an antiblocking agent, a close contact improver, and the like can be added. From the viewpoint of controlling the film properties such as the diffusivity, reflectivity, light shielding property, viscoelasticity, and the like of the resin composition layer, it is preferable to contain an inorganic filler, a dispersant, a surface adjusting additive, a hardening accelerator, a hardening retarder, and a close contact improver.

[0182] As the inorganic filler, for example, there can be mentioned: silicon dioxide, aluminum oxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorillonite, bentonite, boron nitride, aluminum nitride, titanium nitride, and the like, inorganic compounds not containing phosphorus.

[0183] Among these, from the viewpoint of the scratch resistance of the coating film, titanium oxide, titanium nitride, silicon dioxide, talc, mica, kaolinite, or montmorillonite is preferable, and titanium oxide, titanium nitride, silicon dioxide is more preferable.

[0184] In the present disclosure, two or more kinds of inorganic fillers can also be contained from the viewpoint of the scratch resistance of the coating film. Specifically, a combination containing silicon dioxide and one or more kinds selected from the group consisting of titanium oxide, titanium nitride, talc, mica, kaolinite, or montmorillonite can be preferably mentioned.

[0185] From the viewpoint of the embeddability, the content ratio of the inorganic filler (the total content ratio in the case of containing two or more kinds) is preferably 0.01 to 10 mass% and more preferably 0.1 to 5 mass%, based on the total amount (100 mass%) of the resin composition layer. By containing 0.01 to 10 mass% of the inorganic filler, the effect of improving the flowability of the resin composition layer in the pressing step is easily exhibited, and the embeddability is improved.

[0186] The average primary particle diameter (hereinafter, particle diameter) of the inorganic filler is preferably 1 to 100 nm. By setting the particle diameter to 1 nm or more, the viscosity of the resin composition is easily maintained at a level suitable for coating. In addition, by setting the particle diameter to 100 nm or less, the scratch resistance is improved. Furthermore, the particle diameter of the inorganic filler can be found from the average value of the primary particles, that is, the average value of about 20 primary particles that can be observed from an image amplified to about 500,000 to 1,000,000 times by a transmission electron microscope (TEM).

[0187] The inorganic filler can also be dispersed and treated into the resin (A) by mechanical crushing. In the dispersion and treatment, a dispersant is preferably used. In the present disclosure, the dispersant has a function of imparting repulsive force between the particles to prevent the particles that have been divided by the dispersion and treatment from re-aggregating.

[0188] As the dispersant, a conventionally known compound can be used, and for example, a high molecular dispersant, a pigment derivative dispersant, or a compound not containing a phenolic hydroxyl group and phosphorus selected from a cationic, anionic, or nonionic surfactant can be mentioned. The weight average molecular weight (Mw) of these dispersants can be set to about 1,000 to 9,999, for example.

[0189] As the surface adjusting additive, a compound not containing a phenolic hydroxyl group and phosphorus among surface active agents having a weight average molecular weight (Mw) of 1,000 to 9,999, such as a silicon-based, a silicon-acryl-based, an acryl-based, a fluorine-based, an ethynyl glycol-based, etc., can be exemplified. Among them, from the viewpoint of adhesiveness to the adherend, a surface active agent containing a silicon-based, a silicon-acryl-based is particularly preferable.

[0190] As the silicon-based surface adjusting additive, for example, a modified polysiloxane compound in which an organic group is introduced to a part of the methyl group of polydimethylsiloxane is preferable. As the modification, polyether modification, methylstyrene modification, alcohol modification, alkyl modification, aralkyl modification, fatty acid ester modification, epoxy modification, amine modification, amino modification, mercapto modification, etc. can be exemplified, but is not particularly limited to these. These modifications can be used in combination. Among them, from the viewpoint of compatibility, etc., a polyether-modified polysiloxane compound, an aralkyl-modified polysiloxane compound is preferable. As the silicon-acryl-based surface adjusting additive, for example, from the viewpoint of compatibility, etc., a graft copolymer of an acrylic resin and a siloxane-based compound, i.e., a siloxane-modified acrylic resin is preferable. From the viewpoint of application suitability, the content of the surface adjusting additive is preferably 0.01 to 10 mass%, more preferably 0.1 to 5 mass% based on the total amount (100 mass%) of the resin composition layer.

[0191] 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 hardening accelerator. The hardening accelerator is not particularly limited and can be appropriately selected. As specific examples of the hardening accelerator, for example, an amine-based hardening accelerator, a guanidine-based hardening accelerator, a metal-based hardening accelerator can be exemplified. These can be used alone or in combination of two or more.

[0192] From the viewpoint of application suitability, the content of the hardening accelerator is preferably 0.01 to 10 mass%, more preferably 0.1 to 5 mass% based on the total amount (100 mass%) of the resin composition layer.

[0193] As the adhesiveness improver, a compound not containing a phenolic hydroxyl group and phosphorus among oligomers having a weight average molecular weight (Mw) of 1,000 to 9,999 can be exemplified. An acryl resin, a urethane acryl resin, a rosin-based resin, a terpene-based resin, an alicyclic petroleum resin, an aromatic petroleum resin, etc. can be exemplified.

[0194] 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 viewpoint of the adhesion to the adherend and the tear resistance, the content of the adhesion improver is preferably 0.1 to 20 mass%, and more preferably 1 to 15 mass%, based on the total amount (100 mass%) of the resin composition layer.

[0195] Examples

[0196] Hereinafter, the present disclosure will be specifically described by examples and comparative examples, but the present disclosure is not particularly limited to the examples. Furthermore, in the following description, "parts" and "%" each mean "mass parts" and "mass%", respectively, unless otherwise specifically stated.

[0197] The values obtained in the present examples are values obtained by the following method.

[0198] [Glass transition temperature (Tg) of resin (A)]

[0199] The coating liquid of the resin (A) was applied to the release layer of a second release liner (manufactured by Tohcello Corporation, SP-PET-O3) having a thickness of 75 μm so that the dried thickness would be 25 μm, and after drying in a hot air oven at 100°C for 3 minutes, the first release liner (manufactured by Tohcello Corporation, SP-PET-O1) having a thickness of 50 μm was attached to the release layer side of the resin (A). Then, the first release liner was peeled off from the second release liner, and the Tg of the obtained resin (A) was measured using a differential scanning calorimeter (manufactured by TA Instruments, "Discovery DSC 2500"). About 2 mg of the sample was weighed and placed in an aluminum pan, and the differential scanning calorimeter was used with an aluminum pan of the same type as the reference, and after keeping at 100°C for 5 minutes, the sample was rapidly cooled to -50°C using liquid nitrogen. Thereafter, the temperature was increased at a rate of 5°C / minute, and the glass transition temperature (Tg) of the resin (A) was determined from the obtained differential scanning calorimetry (DSC) chart.

[0200] [Weight average molecular weight (Mw) and number average molecular weight (Mn)]

[0201] For the measurement of the weight average molecular weight (Mw) and the number average molecular weight (Mn), the weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated by using a GPC "LC-GPC system" manufactured by Shimadzu Corporation and converting polystyrene having a known molecular weight as a standard substance.

[0202] Apparatus name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation

[0203] Column: GMHXL manufactured by Tosoh Corporation, 4 pieces, HXL-H manufactured by Tosoh Corporation, 1 piece

[0204] Mobile phase solvent: Tetrahydrofuran

[0205] Flow rate: 1.0 mL / min

[0206] Column temperature: 40°C

[0207] [Solid content]

[0208] The mass of the aluminum cup (W0) was measured using a precision balance. Then, about 1 g of each sample was placed in the aluminum cup, and the mass of the sample with the aluminum cup (W1) was measured using a precision balance. The sample with the aluminum cup was heated in an oven at 150°C for 120 minutes, removed from the oven, and allowed to cool to room temperature. The residual mass of the heated sample with the aluminum cup (W2) was measured using a precision balance. Then, the solid content was calculated by the formula (W2-W0) / (W1-W0) x 100 (%).

[0209] [Acid value]

[0210] Here, the "acid value" represents the acid value per 1 g of the solid content of the resin (A), and was calculated according to Japanese Industrial Standards (JIS) K 0070 by potentiometric titration.

[0211] [Resin (A)]

[0212] [Manufacturing example of (meth)acrylic resin (a) (R-1)]

[0213] In a reaction vessel (hereinafter, referred to as "reaction vessel") including a stirrer, a thermometer, a reflux cooling tube, a dropping device, a nitrogen gas introduction tube, ethyl acetate 80 parts, methyl acrylate 35 parts, 2-ethylhexyl acrylate 34.4 parts, 2-ethylhexyl methacrylate 30 parts, acrylic acid 0.3 part, hydroxybutyl acrylate 0.3 part, and 2,2'-azobisisobutyronitrile 0.1 part as an initiator were charged, and the atmosphere in the reaction vessel was replaced with nitrogen gas. Thereafter, while stirring was performed under a nitrogen atmosphere, the temperature was raised to 65°C and the reaction was started. Thereafter, the reaction solution was allowed to react at 65°C for 4 hours. After the completion of the reaction, the solution was cooled, diluted with ethyl acetate, and a (meth)acrylic resin (a) (R-1) having a weight average molecular weight (Mw) of 20,000, a dispersity (Mw / Mn) of 2, a glass transition temperature (Tg) of -32°C, an acid value of 2 mgKOH / g, and a solid content of 25% was obtained.

[0214] [Manufacture Example of (Meth)Acrylic Resin (a) (R-2 to R-12)]

[0215] The (meth)acrylic resin (a) (R-2 to R-12) was manufactured by the same method as in the manufacture of the (meth)acrylic resin (a) (R-1), except that the composition and blending amount (parts by mass) shown in Table 1 were changed. In addition, a blank indicates that it was not blended, and the solid content was 25% in each case.

[0216]

[0217] The abbreviations in the table are as described below.

[0218] [Alkyl Acrylate (al)]

[0219] MA: Methyl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 1)

[0220] BA: n-Butyl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 4)

[0221] HA: Hexyl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 6)

[0222] CHA: Cyclohexyl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 6)

[0223] 2EHA: 2-Ethylhexyl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 8)

[0224] LA: Lauryl Acrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 12)

[0225] [Methacrylic Alkyl Ester (a2)]

[0226] MMA: Methyl Methacrylate (Carbon Number of Saturated Aliphatic Hydrocarbon Group: 1)

[0227] nBMA: n-butyl methacrylate (carbon number of saturated aliphatic hydrocarbon group: 4)

[0228] 2EHMA: 2-ethylhexyl methacrylate (carbon number of saturated aliphatic hydrocarbon group: 8)

[0229] [(meth)acrylic acid (a3)]

[0230] AA: acrylic acid

[0231] MAA: methacrylic acid

[0232] [Others]

[0233] 4HBA: hydroxybutyl acrylate

[0234] [Manufacturing example of urethane resin (R-13)]

[0235] A glass-made flask including a stirrer, a thermometer, a reflux cooler, a nitrogen introduction tube, and a pressure reducing device was charged with terephthalic acid 166 parts, adipic acid 146 parts, and 3-methyl-1,5-pentanediol 212 parts, and ethylene glycol 25 parts, and stirring was performed while nitrogen was introduced, and slow temperature increase was performed under normal pressure, and reaction was performed at 200°C to 230°C for about 8 hours, and a liquid material having an acid value of 43 mgKOH / g was obtained. Subsequently, tetra-n-butoxytitanium 0.01 part was charged, and after nitrogen replacement, stirring was performed at 180°C for 30 minutes under a closed state. Subsequently, reaction was performed at 230°C and 5 mmHg for 2 hours, and a polyester diol having an acid value of 1.1 mgKOH / g, a hydroxyl value of 114.2 mgKOH / g, a weight average molecular weight (Mw) of 982, and a color phase of 10 (American Public Health Association (APHA) method, the same applies hereafter) was obtained.

[0236] Subsequently, a reaction vessel including a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube was charged with the polyester diol 734 parts, dimethylolpropionic acid 23.9 parts, toluene diisocyanate 219 parts, and toluene 242 parts, and reaction was performed at 50°C for 8 hours under a nitrogen atmosphere. Toluene 1200 parts was added thereto, and a solution of a urethane prepolymer having an isocyanate group at the terminal was obtained.

[0237] Next, the obtained solution of the prepolymer was warmed to 70°C, and a solution prepared by mixing 1,3-diaminopropane 20.0 parts, benzylamine 3.1 parts, 2-propanol 600 parts, and toluene 961 parts was added dropwise over 1 hour while maintaining the temperature. After the completion of the dropwise addition, further reaction was carried out at 70°C for 6 hours, whereby a solution of urethane resin (R-13) having a weight average molecular weight (Mw) of 150,000, a dispersity (Mw / Mn) of 4.5, a glass transition temperature (Tg) of 18°C, an acid value of 10 mgKOH / g, and a solid content of 25% was obtained.

[0238] [Example 1]

[0239] [Manufacturing Example of Resin Composition]

[0240] While stirring with a disperser, a solution of the (meth)acrylic resin (a) (R-2) as the resin (A): 374 parts (resin (A) 93.5 parts, solvent 280.5 parts), a phosphorus-containing compound (B1) as the embedment improver (B), namely, Adekastab PEP-36: 1 part, a compound (B2) containing a phenolic hydroxyl group, namely, AO-80: 0.5 part, a crosslinking agent as the other component, namely, an epoxy-based crosslinking agent, jER (registered trademark) YX8034 (manufactured by Mitsubishi Chemical Corporation): 5 parts, 2-butanone as the solvent: 55 parts were sequentially added, and stirring was carried out until they were sufficiently uniform. Subsequently, filtration was carried out using a membrane filter having a pore diameter of 10 μm to remove coarse foreign matter that would be a cause of uneven coating, and a resin composition having a nonvolatile content of 23% was obtained. Furthermore, the embedment improver (B) and the other component were set to the amount in terms of solid content.

[0241] [Manufacturing Example of Sealing Sheet]

[0242] The resin composition was applied to the release layer of a second release liner (manufactured by Tohcello Corporation, SP-PET-O3) having a thickness of 75 μm in such a manner that the thickness after drying became 25 μm, and dried in a hot air oven at 100°C for 3 minutes, whereby a resin composition layer was formed. Subsequently, the first release liner (manufactured by Tohcello Corporation, SP-PET-O1) having a thickness of 50 μm was attached to the resin composition layer with the release layer side facing outward, and aged at 0°C for 7 days, whereby a sealing sheet of Example 1 in which the first release liner / resin composition layer / second release liner were stacked in this order was obtained.

[0243] [Thickness Tt of Sealing Sheet, Thickness Ta of Resin Composition Layer, Thickness Tl of First Release Liner, Thickness Th of Second Release Liner]

[0244] Ten points at equal intervals were determined in the range from the end to the other end in the width direction of the sealing sheet cut to a size of 10 cm x 10 cm, the thicknesses of the 10 points were measured, and the average thereof was set as the thickness Tt of the sealing sheet. Next, the first release liner was peeled from the sealing sheet, and the thicknesses of the first release liner after peeling at the 10 points corresponding to the same positions were measured. The average thereof was set as Tl. Thereafter, the second release liner was further peeled from the resin composition layer, and the thicknesses of the second release liner after peeling at the 10 points corresponding to the same positions were measured. The average thereof was set as Th. The thickness Ta of the resin composition layer was obtained by the following (Formula 1). In addition, the thicknesses were measured using an MH-15M (manufactured by Nikon Corporation).

[0245] Ta = Tt - Tl - Th (Formula 1)

[0246] [Tan δ of resin composition layer]

[0247] A sealing sheet, which was separately produced so as to have a thickness of 50 μm after drying, was cut to a size of 0.5 cm x 2 cm, and the first release liner and the second release liner were peeled off. The dynamic viscoelasticity of the resin composition layer obtained was measured using a dynamic viscoelasticity measuring device DVA-200 / L2 (manufactured by IT Measurement Control Corporation) at a frequency of 10 Hz, in a measurement temperature range of -50°C to 150°C, at a temperature elevation rate of 5°C / minute, in a tensile mode, and tan δ was plotted. Tan δ at 40°C (tan δ40), the peak temperature of tan δ (tan δ peak temperature), and the peak intensity of tan δ (tan δ peak intensity) were read from the obtained graph.

[0248] [Method of evaluation, criteria]

[0249] [Light resistance]

[0250] The sealing sheet was cut to a size of 2 cm x 5 cm, a glass plate (cyan plate glass, manufactured by Kikugawa Co., Ltd.) having a thickness of 1.1 mm was attached to the surface after peeling off the first release liner, and heat press molding (100°C, 5 MPa, 5 minutes) was performed. Further, the second release liner of the sealing sheet was peeled off, and the test piece including the glass plate and the resin composition layer was left to stand at 180°C for 120 minutes, whereby the glass plate and the resin composition layer were tightly attached. Next, the spectral transmittance at 380 nm of the resin composition layer on the glass plate was measured using an ultraviolet-visible spectrophotometer V-570 (manufactured by Shimadzu Corporation), and the obtained value was set as the initial transmittance.

[0251] The resin composition layer on the glass plate was set in a xenon weather meter XL75 manufactured by Suga Test Instruments Co., Ltd. under conditions of a black panel temperature of 50°C and an irradiation amount of 100,000 Lux, and exposed for 300 hours. After the exposure, the spectral transmittance at 380 nm was measured in the same manner as the initial transmittance, and the obtained value was taken as the transmittance after the exposure. Using the formula "|initial transmittance - transmittance after exposure| = change in transmittance", the change in transmittance was calculated. The evaluation criteria were as described below, and A to C were taken as good.

[0252] A: Change in transmittance less than 0.2

[0253] B: Change in transmittance 0.2 or more and less than 0.4

[0254] C: Change in transmittance 0.4 or more and less than 0.6

[0255] D: Change in transmittance 0.6 or more

[0256] [Embeddability]

[0257] A glass substrate on which concave-convex processing had been performed so as to mimic the concave-convex of a micro LED substrate (size 1 cm x 1 cm, width of concave portion 20 μm, height of convex portion 20 μm, width of convex portion 20 μm) was prepared. A schematic cross-sectional view of the test substrate is shown in Figure 3 .

[0258] The sealing sheet was cut into a size of 2 cm x 2 cm, the first or second release liner was peeled off to expose the resin composition layer, and the resin composition layer side was placed on the concave-convex portion of the glass substrate. Thereafter, on the surface exposed by peeling off the release liner on the opposite side, a TPX (Opulent X-44B, manufactured by Tohcello Corporation) having a thickness of 50 μm as a buffer material, and a vinyl chloride film (Celeb T, manufactured by Okamoto Corporation) having a thickness of 2.0 mm were sequentially stacked, and further a paper board was stacked to prevent sticking. Next, the substrate surface was pressed from above the test piece at 5 MPa and 100°C for 20 minutes to fill the resin composition layer into the concave-convex portion of the glass substrate, thereby forming a sealing layer. After the pressing, the buffer material and the paper board were peeled off. The resin composition layer protruding from the glass substrate of the obtained test piece was removed by using a knife, and further filing was performed, thereby removing the resin composition layer remaining on the side surface of the glass substrate to expose the side surface of the glass substrate, thereby becoming a state in which the concave-convex portion of the glass substrate was observable. The embedding property was evaluated by observing the concave portion of the glass substrate at 20 arbitrary places 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 was 5 μm or less was set as a groove being embedded. The evaluation criteria are described below, and A to C were set as good.

[0259] A: 18 or more grooves were embedded

[0260] B: 17 or less and 15 or more grooves were embedded

[0261] C: 14 or less and 12 or more grooves were embedded

[0262] D: 11 or less grooves were embedded

[0263] [Sealing property]

[0264] The sealing sheet was cut into a size of 2 cm x 8 cm, and a glass plate (a blue plate glass, manufactured by Kikugawa Co., Ltd.) having a thickness of 1.1 mm and a size of 2.5 cm x 10 cm was attached to the surface after peeling off the first release liner, and heat pressing (100°C, 5 MPa, 5 minutes) and caulking were performed. Further, the second release liner of the sealing sheet was peeled off, and the test piece including the glass plate and the resin composition layer was left to stand at 180°C for 120 minutes, thereby causing the glass plate and the resin composition layer to be sealed, and a test piece including the glass plate and the resin composition layer was produced.

[0265] A "CT1835" manufactured by Nichiban Co. was attached to the portion subjected to the lattice cutting so as to be in close contact with the resin composition layer, using a cross-cut guide and a cutting knife to make a 1 mm square right-angled lattice pattern (25 cells) in the resin composition layer according to JIS K 5600-5-6 (cross-cut method). The peeling was performed at an angle of approximately 60° within 5 minutes after the attachment, at 0.5 to 1.0 seconds. The state of the peeled resin composition layer was observed, and the adhesiveness was evaluated. The evaluation criteria are described below, and A to C are good.

[0266] A: 0 cells were completely peeled, and no partial peeling was found at the end of the cut.

[0267] B: 0 cells were completely peeled, and partial peeling was found only at the end of the cut.

[0268] C: 1 or more and 2 or less cells were peeled

[0269] D: 3 or more cells were peeled

[0270] [Peeling property]

[0271] The sealing sheet was cut into 2 cm x 8 cm, and a glass plate (cyan plate glass, manufactured by Kikugawa Co., Ltd.) having a thickness of 1.1 mm and a size of 2.5 cm x 10 cm was attached to the surface from which the first release liner was peeled. The test piece was subjected to heat press (100°C, 5 MPa, 5 minutes) and was subjected to pressure bonding. Three pieces of the test piece were prepared, and were subjected to heat aging treatment one by one under the conditions shown below at three levels. Condition (1) was to stand for 60 minutes at 220°C, condition (2) was to stand for 120 minutes at 180°C, and condition (3) was to stand for 240 minutes at 120°C. After the heat aging, the test piece was allowed to stand for 1 hour or more under the conditions of 23°C and 50% relative humidity.

[0272] Subsequently, the second release liner was peeled 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, and the presence or absence of peeling was observed.

[0273] The evaluation criteria are described below, and A to C are good.

[0274] A: No peeling was found under any of the heat aging conditions.

[0275] B: Peeling was found under any of the heat aging conditions.

[0276] C: Peeling was found under any two of the heat aging conditions.

[0277] D: Peeling was found under any of the heat aging conditions.

[0278] Each of the evaluations was performed in accordance with the following 4 stages: A for particularly excellent, B for excellent, C for good, and D for not reaching the target performance. In addition, the resin composition layer in which all of the performance evaluations were A to C was in accordance with the present disclosure.

[0279] [Examples 2 to 41], [Comparative Examples 1 to 7]

[0280] Sealing sheets were produced by the same method as in Example 1, except that the content ratio and thickness Ta shown in Tables 2 to 5 were changed, and evaluation was similarly performed. In addition, each of the other components was also added at the same time.

[0281] In Tables 2 to 5, the amounts of the resin (A), the embedment improver (B), and the other components are amounts converted to solid content, and a blank indicates that the component was not formulated.

[0282] The abbreviations in the tables are as described below.

[0283] B1-1: Phosphorus-containing compound (Adekastab PEP-36, manufactured by ADEKA Co., Ltd., skeleton containing 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, molecular weight 633)

[0284] B1-2: Phosphorus-containing compound (Adekastab HP-10, manufactured by ADEKA Co., Ltd., skeleton containing diphenyl monoalkyl phosphite, molecular weight 583)

[0285] B1-3: Phosphorus-containing compound (Adekastab 3010, manufactured by ADEKA Co., Ltd., skeleton containing trialkyl phosphite, molecular weight 503)

[0286] B2-1: Phenolic hydroxyl group-containing compound (Adekastab AO-80, manufactured by ADEKA Co., Ltd., semi-hindered, molecular weight 741)

[0287] B2-2: Phenolic hydroxyl group-containing compound (Adekastab AO-330, manufactured by ADEKA Co., Ltd., hindered, molecular weight 775)

[0288] B2-3: Phenolic hydroxyl group-containing compound (IRGANOX (registered trademark) 1010, manufactured by BASF Japan Ltd., hindered, molecular weight 1,178)

[0289] C-1: Epoxide compound (jER (registered trademark) YX8034, manufactured by Mitsubishi Chemical Corporation)

[0290] C-2: Isocyanate compound (Cosmonate (registered trademark) T100, manufactured by Mitsui Chemicals Fine, Inc.)

[0291] C-3: Aziridine compound (Chemitite (registered trademark) PZ-33, manufactured by Japan Catalyst Corporation)

[0292] C-4: Silane coupling agent (KBE-403, manufactured by Shin-Etsu Silicone Corporation)

[0293] F-1: Silica (AEROSIL (registered trademark) R972, manufactured by Evonik Degussa Corporation)

[0294]

[0295]

[0296]

[0297]

[0298] In the present disclosure, in the case of a sealing sheet in which 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, it was found that there were problems in embeddability. In addition, in the case of a sealing sheet in which the thickness Ta of the resin composition layer was outside the range of 1 μm to 100 μm, as shown in Comparative Examples 3 to 4, it was found that there were problems in embeddability and in tearability. Furthermore, in the case where the embeddability improver (B) did not contain both the phosphorus-containing compound (B1) and the phenolic hydroxyl group-containing compound (B2), as shown in Comparative Examples 5 to 7, it was found that there were problems in light resistance, embeddability, and adhesiveness.

[0299] As described in Table 5, the sealing sheets of Comparative Examples 1 to 7 could not satisfy the light resistance and the embeddability in a good balance and at a high level. In addition, the adhesiveness and the tearability could not be satisfied at a high level.

[0300] In contrast, according to Examples 1 to 41, as described in Tables 2 to 5, the sealing sheets of the present disclosure exhibited excellent light resistance, and the embeddability was also excellent. Furthermore, the adhesiveness or the tearability was also excellent, and thus it was found that the sealing sheets of the present disclosure could be favorably used for sealing of a plurality of light emitting elements.

Claims

1. A sealing sheet for sealing a light emitting element used in a display having a plurality of light emitting elements as light sources, the sealing sheet comprising a resin composition layer containing a resin (A) and a burying property modifier (B), the resin (A) having 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 burying property modifier (B) containing a phosphorus-containing compound (Bl) and a phenolic hydroxyl group-containing compound (B2), the resin composition layer having a loss tangent at 40°C (tan δ40) of 0.8 to 2.0 obtained by dynamic viscoelasticity measurement at a frequency of 10 Hz in a tensile mode, the resin composition layer having a thickness Ta of 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) being a copolymer containing a constitutional unit derived from an alkyl acrylate (al) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 12, and a constitutional unit derived from an alkyl methacrylate (a2) having a linear, branched or cyclic saturated aliphatic hydrocarbon group having a carbon number of 1 to 8.

3. The sealing sheet according to claim 2, wherein the (meth)acrylic resin (a) further contains a constitutional unit derived from (meth)acrylic acid (a3).

4. The sealing sheet according to claim 1, comprising 76 mass% to 99.9 mass% of the resin (A) with respect to the total mass of the resin composition layer.

5. The sealing sheet according to claim 1, wherein the content of the burying property modifier (B) is 0.1 mass% to 15 mass% with respect to the total mass of the resin composition layer.

6. The sealing sheet according to claim 1, wherein the mass ratio of the phosphorus-containing compound (Bl) to the phenolic hydroxyl group-containing compound (B2) in the burying property modifier (B) is 0.1:1 to 10:

1.

7. A display having a sealing layer comprising a resin composition layer of the sealing sheet according to any one of claims 1 to 6.

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