Sealing sheet, display panel and method for manufacturing display panel

Abstract

To provide a sealing sheet capable of preventing an LED element from blocking, easily changing a mounting position, preventing poor appearance and preventing a gap from occurring in the bottom and corner part of a recessed part.SOLUTION: A sealing sheet for sealing between a plurality of light emitting elements for displays using the light emitting elements as a light source includes a first film, a resin composition layer for forming a sealing layer and a second film arranged in this order. The resin composition layer has a surface roughness Ra of 0.02 μm or more on a surface contacting the first film and 20°C or more of a glass transition temperature obtained by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1 Hz and 0.2 or more of a loss tangent (tanδ100) at 100°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an encapsulating sheet, and more particularly to an encapsulating sheet including a resin composition layer for encapsulating a micro LED used in a display using a micro LED as a light source, a display panel having an encapsulating layer formed from the resin composition layer, and a method for manufacturing a display panel. [Background technology]

[0002] In recent years, displays have been actively developed using various light-emitting elements in order to achieve even higher performance. Specifically, various display specifications are being researched, such as backlit displays using liquid crystal or quantum dots, displays using self-luminous elements such as mini / micro LEDs and organic EL, plasma displays, and electrophoretic displays, and a wide range of uses are being considered, from large display applications such as signage and televisions to small-sized applications such as tablets, personal computers, smartphones, and wearable devices. In particular, development of displays using LEDs is progressing at an increasing pace, and Patent Documents 1 to 4 describe encapsulating sheets for encapsulating multiple LED elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-12051 [Patent Document 2] International Publication No. 2021 / 200035 [Patent Document 3] International Publication No. 2021 / 245830 [Patent Document 4] International Publication No. 2022 / 145399 Summary of the Invention [Problem to be solved by the invention]

[0004] As LED elements have become increasingly smaller in recent years, the spacing between the LED elements and the distance from the substrate have become narrower. Conventional encapsulating sheets have excellent heat resistance and ease of handling, but have the following problems: When the encapsulating sheet is placed on the upper surface of multiple micro-sized LED elements, even if an attempt is made to change the position, the encapsulating resin composition layer sticks to the upper surface of the LED elements, making it difficult to change the position. Furthermore, when the encapsulating resin composition layer was forced into the recesses between multiple micro-sized LED elements, it was not possible to sufficiently remove the air between the substrate on which the LED elements were mounted and the encapsulating resin composition layer, leaving large air bubbles (over 100 μm) between the substrate and the encapsulating resin composition layer at the bottom of the recesses between the multiple LED elements, which resulted in a very poor appearance when viewed from the substrate side and was one of the causes of low yields.

[0005] An object of the present invention is to provide an encapsulating sheet that is unlikely to cause blocking of LED elements, that allows easy change of the mounting position, that is unlikely to cause poor appearance, and that is unlikely to cause voids on the bottom surface or corners of recesses. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result have arrived at the inventions described in [1] to [8] below. That is, [1]: An encapsulating sheet for sealing spaces between light-emitting elements for a display using a plurality of light-emitting elements as a light source, the encapsulating sheet comprising a first film, a resin composition layer for forming a sealing layer, and a second film arranged in this order, the resin composition layer on a surface in contact with the first film having a surface roughness Ra of 0.02 μm or more, the resin composition layer having a glass transition temperature of 20° C. or more, and a loss tangent (tanδ) at 100° C., the glass transition temperature being measured by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1 Hz. 100 ) is 0.2 or more.

[0007] [2]: Loss tangent at 100℃ (tanδ 100) is 2.5 or less. [3]: The encapsulating sheet according to the above [1] or [2], wherein a cut level difference RΔc of the contour curve of the resin composition layer on the surface in contact with the first film is 0.05 to 20 μm. [4] The loss modulus (G'') of the resin composition layer at 100°C obtained by dynamic viscoelasticity measurement at a frequency of 1 Hz. 100 ) but 5×10 3 Pa~2×10 7 The encapsulating sheet according to any one of the above [1] to [3], wherein the encapsulating sheet is Pa. [5]: The encapsulating sheet according to any one of the above [1] to [4], wherein the resin composition layer has a thickness Ta of 1 to 100 μm.

[0008] [6]: A display panel having an encapsulating layer made of a resin composition layer of the encapsulating sheet according to any one of [1] to [5] above.

[0009] [7]: A method for manufacturing a display panel, comprising the following steps (1) to (6): (1) A step of preparing an encapsulating sheet according to any one of [1] to [5] above, in which a first film, a resin composition layer for forming an encapsulating layer, and a second film are arranged in this order; (2) preparing an object to be sealed, in which a plurality of light-emitting elements are arranged at intervals on one surface of a substrate; (3) peeling the first film from the encapsulating sheet to expose the resin composition layer for forming the encapsulating layer; (4) contacting the exposed resin composition layer for forming a sealing layer with the light-emitting surfaces of the plurality of light-emitting elements; (5) filling spaces between the plurality of light-emitting elements with a resin composition layer for forming a sealing layer; (6) Peeling off the second film. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an encapsulating sheet that is less likely to block LED elements, is easy to change the mounting position, is less likely to cause poor appearance, and is less likely to cause voids on the bottom surface or corners of recesses. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure of an encapsulating sheet. [Figure 2] 10A to 10C are schematic cross-sectional views showing a step of sealing a light-emitting element on a substrate having the light-emitting element. [Figure 3] FIG. 1 is a cross-sectional view showing an example of a test substrate that mimics a micro LED substrate. [Figure 4] FIG. 10 is a schematic cross-sectional view for explaining an image of a cut level difference Rδc of a profile curve. [Figure 5] FIG. 2 is a schematic diagram illustrating a method for evaluating blocking resistance in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure will be described in detail below. Note that the embodiments described below are examples of the present disclosure. The present disclosure is not limited to the following embodiments, and includes modifications that are implemented within the scope of the present disclosure. In this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limit values. (Meth)acrylic acid refers to acrylic acid and methacrylic acid. Furthermore, unless otherwise noted, the various components appearing in this specification may each be used independently as a single type or in combination of two or more types. When two or more types are used in combination, the total content is used.

[0013] [Form of encapsulating sheet] As shown in Fig. 1, the encapsulating sheet of the present disclosure has a first film, a resin composition layer, and a second film arranged in this order. A plurality of resin composition layers can be provided. When the three-layer structure shown in Fig. 1 is adopted, the resin composition layer can be formed on the second film and then the first film can be laminated thereon, or the resin composition layer can be formed on the first film and then the second film can be laminated thereon, and the former manufacturing method is preferred. After or during the production of the encapsulating sheet, the encapsulating sheet is wound around a core in a roll shape to obtain an encapsulating sheet roll. The winding length can be designed depending on the application. From the viewpoint of increasing productivity, it is preferably 50 m or more, and more preferably 100 m or more. From the viewpoint of production yield, the winding length is preferably 10,000 m or less. When the encapsulating sheet is in the form of a roll, it is preferable to provide the first film on the outer side of the winding.

[0014] The encapsulating sheet of the present disclosure is used to seal between light-emitting elements in a display that uses a plurality of light-emitting elements as a light source. The light-emitting elements are preferably micro LEDs, and the light-emitting colors thereof are not particularly limited, but examples thereof include red, green, and blue. The encapsulating sheet of the present disclosure is preferably used to seal a micro LED array in which a large number of elements of the three colors are regularly arranged on a substrate. That is, the encapsulating sheet of the present disclosure is preferably used to seal between red (R) elements and green (G) elements, between G elements and blue (B) elements, between B elements and R elements, or between [R element, G element, B element] units. The resin composition layer is preferably directly attached to the micro LED for sealing. The micro LED is preferably disposed on a substrate made of, but not limited to, acrylic, urethane, polycarbonate, epoxy, polyimide, glass, paper, cloth, aluminum, ceramic, or polyethylene terephthalate, and has an electrode portion.

[0015] The resin composition layer has high conformability to uneven surfaces, so it is suitable for use in conforming to the micro LEDs and filling the spaces between them. By filling the spaces between the micro LEDs with the resin composition layer, a sealing layer made of the resin composition layer is formed. The sealing layer has the function of fixing adjacent micro LEDs and preventing them from falling off. It is particularly preferable to use the resin composition layer as a sealing layer for a micro LED display panel. Micro LEDs are tiny LED elements (chips) measuring 50 μm or less or 100 μm in size. By mounting multiple micro LEDs on a substrate with wiring and circuits, a display using multiple optical semiconductor elements as light sources is formed. Micro LEDs are made up of LED elements such as GaAs, GaP, AlGaInP, and InGaN, as well as sealing resin, a package substrate, electrodes, etc., and have an operating temperature of 25 to 60°C. An example of a process for forming a sealing layer will be described below with reference to FIG. Although not shown, a step preceding the step (a) shown in Figure 2 is to prepare an object to be sealed, which has multiple micro LEDs arranged at intervals on one side of a substrate.

[0016] Step (a): Step of placing the encapsulating sheet As shown in Figure 2(a), the first film is peeled off from the encapsulant sheet to expose the resin composition layer, and then the resin composition layer of the encapsulant sheet is placed on a substrate having multiple micro LEDs so as to directly cover the entire multiple micro LEDs. In this specification, the number of micro LEDs is not particularly limited. In display applications, the number of micro LEDs used is determined by the display size and the number of pixels. The size of the micro LED is less than 100 μm thick and has a planar area of ​​40,000 μm. 2 The following is preferable: a thickness of 50 μm or less and an area in plan view of 10,000 μm 2 The following is more preferable: a thickness of 20 μm or less and a planar area of ​​2,500 μm 2 The following are even more preferred: The spacing between micro LEDs mounted on the substrate is, for example, 10 to 5,000 μm. When a set of red, green, and blue micro LEDs is mounted on the substrate as one pixel, the spacing between the pixels is, for example, 10 to 2,000 μm, preferably 20 to 1,800 μm, and more preferably 500 to 1,500 μm. The spacing between micro LEDs in one pixel is, for example, 10 to 200 μm, preferably 10 to 100 μm, and more preferably 20 to 60 μm.

[0017] Process (b): Filling process As shown in FIG. 2(b), for example, the resin composition layer is fluidized by pressing and filled around the micro LEDs and between the micro LEDs. The resin composition layer filled around the micro LEDs and between the micro LEDs becomes an encapsulating layer. The pressing method is not particularly limited, but heat pressing and vacuum pressing are preferred. From the viewpoint of the filling property of the resin composition layer, the temperature during pressing is preferably 20 to 200°C, more preferably 30 to 150°C, even more preferably 50 to 140°C, and most preferably 70 to 130°C. To improve adhesion to the micro LED or the adherend, heat aging may be further performed after pressing. The heating temperature is preferably 40 to 250°C, more preferably 80 to 220°C, and even more preferably 100 to 190°C. The heating time is preferably 30 to 300 minutes, more preferably 60 to 240 minutes, and even more preferably 90 to 180 minutes. By using the above heating temperature and heating time, residual stress in the resin composition layer can be removed and adhesion can be improved. Heat aging may be performed after step (c), which will be described later. The second film may be peeled off before or after heat aging.

[0018] Step (c): Etching step In step (c), etching may be performed as needed to remove or thin the encapsulation layer on the optical semiconductor element. If step (c) is performed, it is preferable to perform it after peeling off the second film. Removing excess encapsulation layer improves the brightness of the micro LED and ensures visibility during light emission. The thickness of the encapsulation layer after etching is preferably approximately the same as the thickness of the micro LED as shown in Figure 2(c-1) or less than the thickness of the micro LED as shown in Figure 2(c-2). It is not necessary to completely remove the encapsulation layer from the micro LED, as long as it is substantially removed, and some thin film may remain. If sufficient brightness can be ensured, step (c) may be omitted. The etching method is not particularly limited, but preferred examples include wet etching methods such as chemical polishing using chemicals, physical polishing using an abrasive, laser etching, plasma etching using argon plasma or oxygen plasma, and dry etching methods such as ion beam etching. From the viewpoint of reducing surface irregularities, it is preferable to use plasma etching or a combination of wet etching and dry etching. The plasma etching conditions may be, for example, dry etching in an anisotropic plasma device using a CF4 / O2 / N2 mixed gas at an output of 1500-3000 W for 180-600 seconds, with the CF4 gas supply rate being, for example, 50-100 sccm, the O2 gas supply rate being, for example, 500-1000 sccm, and the N2 gas supply rate being, for example, 50-100 sccm.

[0019] As described above, through steps (a) to (c), the encapsulating layer can be formed from the resin composition layer in the encapsulating sheet of the present disclosure. As described above, the sealing sheet of the present disclosure has a resin composition layer for forming a sealing layer sandwiched between a first film and a second film, and can be obtained by applying a coating liquid of a resin composition for forming a resin composition layer onto the second film, drying the coating liquid, and then covering the surface of the resin composition layer with the first film, or by applying a coating liquid of a resin composition for forming a resin composition layer onto the first film, drying the coating liquid, and then covering the surface of the resin composition layer with the second film.

[0020] [Resin composition layer] The resin composition layer contains a resin (A), and at least one of a polymerization initiator (B), a colorant (C), and a crosslinking agent (E), and may further contain other components. In the present disclosure, the resin (A) is a substance that functions as a binder to bond and fix objects together, specifically to a substrate having a micro LED thereon or to fix the micro LED thereon.

[0021] In the present invention, it is important that the surface roughness Ra of the resin composition layer on the surface in contact with the light-emitting element 5 in step (a) shown in Figure 2, in other words, the surface in contact with the first film in Figure 1, is 0.02 μm or more, and it is preferably 60% or less of the thickness Ta of the resin composition layer. By using a resin composition layer with a surface roughness Ra of 0.02 μm or more, the resin composition layer is less likely to adhere excessively to the surface of the micro LED during the process shown in FIG. 2(a), making it easier to correct the placement position. Furthermore, by using a resin composition layer with a surface roughness Ra of 0.02 μm or more, air is less likely to remain at the interface between the substrate and the resin composition layer during the process shown in FIG. 2(b), resulting in a good appearance. That is, a resin composition layer with a surface roughness Ra of 0.02 μm or more is important in terms of suppressing and preventing blocking and air entrapment. The surface roughness Ra is preferably 0.03 μm or more, more preferably 0.1 μm or more, and even more preferably 0.3 μm or more. A larger surface roughness Ra is preferable in terms of suppressing and preventing blocking and air entrapment, but if the surface roughness Ra is too large, there is a risk that the spaces between the micro LEDs and the periphery of the micro LEDs may not be filled sufficiently without gaps during the process shown in Figure 2(b). Therefore, the surface roughness Ra of the resin composition layer is preferably 60% or less of the thickness Ta of the resin composition layer.

[0022] The resin composition layer of the present disclosure has a glass transition temperature (Tg) of 20°C or higher, and a loss tangent (tanδ) at 100°C, as determined by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1 Hz. 100 ) is important to be 0.2 or greater. By having a Tg of 20° C. or higher, the blocking suppression and prevention properties in the step (a) shown in FIG. 2 are improved. 100 When tan δ is 0.2 or more, the resin composition layer becomes more easily deformable and flowable in the step (b) shown in FIG. 2, and the suppression and prevention of air entrapment is improved. 100 is preferably 0.3 to 2.5, more preferably 0.3 to 2.0, and even more preferably 0.3 to 1.8. tanδ 100 When tan δ is 0.2 or more, the pressure applied to the resin composition layer in the pressing step is well diffused, and not only is the air entrapment suppressed and prevented, but also the embeddability, smoothness, and adhesion to the adherend, which will be described later, are improved. 100 By making the ratio 2.5 or less, excessive deformation and flow of the resin composition layer during the pressing process can be suppressed, and a sufficient thickness of the encapsulating layer can be ensured even in the peripheral part of the micro LED. The above-mentioned Tg and tanδ 100 is determined by dynamic viscoelasticity measurement in torsion mode at a frequency of 1 Hz and from -50 to 150°C. tanδ is the ratio of loss modulus to storage modulus, and Tg is the temperature at the peak top of tanδ. 100 is the ratio of loss modulus to storage modulus at 100°C.

[0023] Furthermore, the resin composition layer of the present disclosure has a loss modulus (G'') at 100°C obtained by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1 Hz. 100 ) but 5×10 3 Pa~2×10 7 Preferably, it is 1×10 4 Pa~9×10 6 Pa is more preferable, and 2×10 4 Pa~5×10 5 Pa is more preferred. G'' 100 However, when the thickness is within the above range, the resin composition layer is considered to be able to deform and flow well in the pressing step, and to have improved embeddability, smoothness, and adhesion to the adherend. 100 is 2 x 10 7 By ensuring that the compressive strength is G'' or less, the resin composition layer can be easily deformed and flowed without dissipating energy during the pressing step, and the embedding ability into recesses is improved. 100 is 5 x 10 3 By ensuring that the pressure is equal to or greater than Pa, energy is dissipated during the pressing process, which makes it possible to suppress excessive deformation and flow of the resin composition layer and ensure a sufficient thickness of the encapsulating layer even around the micro LED. Tg and tanδ 100 and G'' 100 can be adjusted by the type and composition of the resin (A), the type and content of the polymerization initiator (B), the type, dispersion state and content of the colorant (C), and the types and contents of the crosslinking agent and monomer, which are other components.

[0024] The dynamic viscoelasticity is preferably measured for a resin composition layer laminated to a thickness of 500 μm or more, as described in the Examples below, by preparing two pairs of encapsulating sheets not having a first film, bonding the resin composition layers together with a laminator to produce a laminate of second film / resin composition layer / second film, and then peeling off the second film from one side of the laminate and repeatedly bonding the resin composition layers of the encapsulating sheets together to a thickness of 500 μm or more, and then measuring the dynamic viscoelasticity. Alternatively, two pairs of encapsulating sheets not having a second film can be prepared, and similarly, resin composition layers having a thickness of 500 μm or more can be formed.

[0025] The thickness Ta of the resin composition layer is preferably 1 to 100 μm, more preferably 2 to 60 μm, further preferably 5 to 50 μm, and particularly preferably 10 to 40 μm, from the viewpoint of embedding properties. By setting the thickness Ta of the resin composition layer within the above range, the pressure applied to the resin composition layer in the pressing step is appropriately dispersed and sufficiently uniformed, thereby improving embeddability. The resin composition layer may be in the form of a single layer or a laminate of two or more layers, and in the case of two or more layers, the total thickness refers to the thickness. The thickness Ta of the resin composition layer can be adjusted by the method for forming the resin composition layer, which will be described later. The thickness Ta in the present disclosure is measured by the method described in the Examples below.

[0026] The thickness Ta of the resin composition layer satisfies the formula (1) 0.1≦Ta / T2≦2, which represents the ratio to the thickness T2 of the second film described below, and more preferably 0.2≦Ta / T2≦1.5, and even more preferably 0.2≦Ta / T2≦1.2. By setting the thickness within the above range, the pressure applied to the resin composition layer in the pressing step described below can be controlled, and the resin composition layer can flow uniformly, resulting in good embeddability.

[0027] Although there are no clear stages, the filling is considered to occur successively through the following two stages: a stage in which the resin composition layer deforms vertically (in the Z-axis direction) toward the bottom of the recess, and a stage in which the resin composition layer, having reached the bottom of the recess, deforms horizontally (in the X-axis and Y-axis directions) so as to cover the entire bottom of the recess. In the present invention, the ease of deformation in the vertical (Z-axis) direction is referred to as embeddability, and the tan δ of the resin composition layer is referred to as embeddability. 100 If the fluidity of the encapsulating resin composition layer is insufficient, the encapsulating resin composition layer cannot be sufficiently filled in the corners of the recesses between multiple micro-sized LED elements, and voids are likely to occur in the corners.

[0028] Furthermore, the ease of deformation in the lateral (X-axis, Y-axis) directions is referred to as smoothness, and is thought to be greatly influenced by the surface roughness Ra of the resin composition layer before pressing. If the surface roughness Ra before pressing is too large, after reaching the bottom of the recess, when the encapsulating resin composition layer deforms in the lateral (X-axis, Y-axis) directions, a very small gap (of about 0.5 μm) is likely to occur between the bottom and the pressed encapsulating resin composition layer. If voids occur at the bottom or corners of the recesses, light refracts and reflects at the voids, resulting in light mixing and adversely affecting the visibility of the display. When the encapsulating resin composition layer is transparent, the presence of minute voids causes light scattering, which is also observed as the magnitude of haze. When the encapsulating resin composition layer is black, even minute voids can cause light leakage. The presence of voids can be observed from the substrate side using a laser microscope. In the present invention, the surface roughness Ra of the interface after pressing can be determined from the state of extremely fine voids observed from the substrate side using a laser microscope, and can be evaluated as smoothness. Since smoothness relates to deformation of the resin composition layer in the lateral (X-axis, Y-axis) directions, it can be simply evaluated using a flat adherend that does not have any recesses formed thereon. Furthermore, if such voids exist, the adhesion of the formed sealing layer to the substrate will be reduced.

[0029] The cut level difference Rδc of the contour curve of the resin composition layer at the surface to be in contact with the object to be sealed is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.5 μm or more, and is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 6 μm or less. The cut level difference Rδc of the profile curve is the difference in level in the height direction that coincides with any two load length ratios, and in the present invention, the two load length ratios are defined as 25% and 75%.

[0030] When the slope of the unevenness on the surface of the first film is gentle, as shown schematically in Figure 4(a), the cut level difference Rδc of the contour curve of the first film becomes small, and when the shape of such a first film with a small cut level difference Rδc of the contour curve is inverted and transferred to the surface of the resin composition layer, the slope of the unevenness on the surface of the resin composition layer also becomes gentle, as shown in Figure 4(a'), and the cut level difference Rδc of the contour curve of the resin composition layer also becomes small. On the other hand, when the slope of the unevenness on the surface of the first film is steep, as shown schematically in Figure 4(b), the difference in cutting level Rδc of the contour curve of the first film becomes large, and when the shape of such a first film with a large difference in cutting level Rδc of the contour curve is inverted and transferred to the surface of the resin composition layer, the unevenness and slope of the surface of the resin composition layer become steep, as shown in Figure 4(b'), and the difference in cutting level Rδc of the contour curve of the resin composition layer also becomes large. When the surface of the resin composition layer is as shown in Fig. 4(b'), the resin composition layer is less likely to adhere to the surface of the micro LED during the process shown in Fig. 2(a), making it easier to correct the placement position and less likely to leave large voids (air pockets) at the bottom of the recess during the process shown in Fig. 2(b). However, on the other hand, during the process shown in Fig. 2(b), it becomes necessary to fill the recess with more resin composition layer, which may result in insufficient filling of the recess or a loss of smoothness. On the other hand, when the surface of the resin composition layer is as shown in Figure 4(a'), it has excellent filling properties into the recess during the process shown in Figure 2(b). However, during the process shown in Figure 2(a), the resin composition layer tends to stick to the surface of the micro LED, making it difficult to adjust the placement position, and there is a risk that a large void (air pocket) will easily remain at the bottom of the recess during the process shown in Figure 2(b). Therefore, it is preferable that the cut level difference Rδc of the contour curve of the resin composition layer is within the above range.

[0031] The resin composition for forming the resin composition layer can be obtained by mixing the resin (A), at least one of the polymerization initiator (B), the colorant (C), and the crosslinking agent (E), and a solvent (a dispersion medium for the colorant (C), abbreviated as solvent). The optional solvent is used to adjust the viscosity and other coating properties when mixing the components constituting the resin composition layer. For example, ester-based, ether ester-based, ether-based, alcohol-based, aromatic-based, or other solvents compatible with the resin (A) can be used as appropriate. Specific examples of suitable solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, cyclohexanone, toluene, xylene, isopropyl alcohol, and N-methyl-2-pyrrolidone. For stirring, a known stirring device can be used, and a disper, mixer, shaker, homogenizer, etc. are preferred. The resin composition not containing the colorant (C) may be produced in two or more steps, first by mixing the resin (A) and an optional solvent to prepare a mixture, and second by adding the resin (A), the polymerization initiator (B), and other components as needed. The resin composition containing the colorant (C) may be produced in two or more steps, firstly by dispersing the colorant (C) in an arbitrary solvent to obtain a dispersion, and secondly by adding the resin (A), the polymerization initiator (B), and other components as necessary. The resin (A) and the dispersant may also be used to obtain the dispersion.

[0032] Resin (A) The weight average molecular weight (Mw) of the resin (A) is preferably 1 million or less, more preferably 300,000 or less, and even more preferably 150,000 or less. By making the weight average molecular weight (Mw) of the resin (A) 1 million or less, entanglement of molecular chains is easily untangled during the heat aging process, improving adhesion. The lower limit of the weight average molecular weight (Mw) of the resin (A) is not particularly limited, but is preferably at least 400, more preferably at least 900, even more preferably at least 3000, still more preferably at least 5000, and most preferably at least 10,000. By making the weight average molecular weight (Mw) of the resin (A) at least 400, the coating strength of the resin composition layer is improved. The weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of polystyrene. The weight average molecular weight (Mw) in the present disclosure is measured by the method described in the examples below.

[0033] The resin (A) can be used alone or in combination of two or more. The content of the resin (A) is preferably 10 to 98 mass %, more preferably 25 to 95 mass %, and even more preferably 60 to 90 mass %, based on the total amount (100 mass %) of the resin composition layer. When two or more types of resin (A) are contained, the content of each resin (A) is preferably 5 mass % or more, and the total content is preferably within the above range. By setting the content of the resin (A) within the above range, compatibility with the colorant (C) is improved when the colorant (C) is contained, and the light-blocking properties are improved.

[0034] Suitable examples of the resin (A) include (meth)acrylic resin (a1), urethane resin (a2) such as polyurethane resin or polyurethane urea resin, epoxy resin (a3), maleic acid resin, styrene-maleic acid copolymer, polystyrene resin, polybutadiene resin, polyester resin, condensation polyester resin, addition polyester resin, melamine resin, polycarbonate resin, oxetane resin, phenoxy resin, polyimide resin, polyamideimide resin, alkyd resin, amino resin, polyamide resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluororesin, butyral resin, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, vinyl resin, rubber resin, cyclized rubber resin, cellulose, polyethylene (HDPE, LDPE), etc. From the viewpoint of embeddability, it is preferable that the resin (A) contains at least one of the (meth)acrylic resin (a1), urethane resin (a2), and epoxy resin (a3). Furthermore, from the viewpoint of adhesion, it is more preferable that the resin contains a (meth)acrylic resin (a1).

[0035] The resin (A) preferably has one or more functional groups that can be used in a polymerization / crosslinking reaction by heat or light. The functional groups may be appropriately selected depending on the reactivity of the resins (A) with each other or with the polymerization initiator (B) and crosslinking agent (E) described below, and may be self-crosslinkable functional groups. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, a silanol group, a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, an unsaturated carboxylic acid group, etc. Radical polymerizable functional groups such as a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, and an unsaturated carboxylic acid group are preferred.

[0036] [(Meth)acrylic resin (a1)] In the present disclosure, the (meth)acrylic resin (a1) is an acrylic copolymer obtained by copolymerizing a (meth)acrylic acid ester monomer, and is a polymer having 2 to 20,000 structural units based on the monomer. A suitable example of the (meth)acrylic acid ester monomer is a (meth)acrylic acid alkyl ester monomer. When a functional group that can be used in polymerization / crosslinking reactions is introduced, a (meth)acrylic copolymer obtained by copolymerizing a functional group-containing monomer and a (meth)acrylic acid ester monomer is preferred. The (meth)acrylic resin (a1) of the present disclosure excludes compounds containing two or more urethane bonds in one molecule and compounds having two or more epoxy groups in one molecule.

[0037] The (meth)acrylic acid alkyl ester monomer is a compound obtained by esterifying (meth)acrylic acid to introduce an alkyl group or a cycloalkyl group, and the alkyl group or the cycloalkyl group may be any of a linear, branched, or cyclic saturated aliphatic hydrocarbon group. The saturated aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and more preferably a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, and (meth)acrylic acid. Examples of suitable acrylates include decyl, 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, and isobornyl (meth)acrylate. Among these, in view of the dispersibility of the colorant (C), 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, and it is most preferable to use methyl (meth)acrylate and n-butyl (meth)acrylate.

[0038] From the viewpoint of adhesion, the (meth)acrylic resin (a1) preferably contains 1 to 100 mass %, more preferably 20 to 99.5 mass %, and even more preferably 80 to 99 mass %, of structural units derived from (meth)acrylic acid alkyl ester monomers, relative to 100 mass % of the monomers constituting the (meth)acrylic resin (a1).

[0039] The (meth)acrylic resin (a1) preferably has a structural unit derived from a functional group-containing monomer and / or an unsaturated bond. Examples of functional group-containing monomers include carboxy group-containing monomers, hydroxy group-containing monomers, epoxy group-containing monomers, and amino group-containing monomers. By including a functional group-containing monomer, the cohesive strength of the resin (A) is improved, and a tough resin composition layer is obtained. In particular, it is preferable to include a carboxy group-containing monomer, a hydroxy group-containing monomer, or an epoxy group-containing monomer.

[0040] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, and isocrotonic acid. Among these, (meth)acrylic acid is preferred from the viewpoint of adhesion.

[0041] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Among these, from the viewpoint of adhesion, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate are more preferred.

[0042] Examples of amino group-containing monomers include (meth)acrylic acid monoalkylamino esters such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate.

[0043] The (meth)acrylic resin (a1) preferably contains structural units derived from functional group-containing monomers in a total amount of 0.1 to 20 mass % relative to 100 mass % of the monomers constituting the (meth)acrylic resin (a1). By adjusting the amount within this range, the adhesive strength can be adjusted. It is preferable that the content of structural units derived from carboxyl group-containing monomers is 0.1 to 10% by mass. When the content is within this range, adhesion can be improved. It is preferable that the content of structural units derived from hydroxyl group-containing monomers is 0.1 to 10% by mass. When the content is within this range, adhesion can be improved.

[0044] For the purpose of introducing an unsaturated bond into the (meth)acrylic resin (a1), a monomer having an epoxy group or a monomer having an isocyanate group can be used. The (meth)acrylic resin (a1) having an unsaturated bond can be obtained by the following two-step reaction. First, a (meth)acrylic copolymer having a carboxyl group is obtained using a monomer having a carboxyl group such as (meth)acrylic acid, or a monomer having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate is used to obtain a (meth)acrylic copolymer having a hydroxyl group. Next, at least a portion (10 to 100 mol%) of the carboxyl groups or hydroxyl groups of the (meth)acrylic copolymer is preferably reacted with an epoxy group or an isocyanate group in a monomer having an unsaturated bond such as an epoxy group or an isocyanate group and a (meth)acryloyl group to introduce an unsaturated bond such as a (meth)acryloyl group into the (meth)acrylic resin (a1). Note that, in the sense of modifying the (meth)acrylic copolymer, a monomer having an epoxy group or an isocyanate group and an unsaturated bond such as a (meth)acryloyl group is sometimes referred to as a modifier. There is no limitation on the amount of unsaturated bonds such as (meth)acryloyl groups introduced. The (meth)acrylic resin (a1) may have carboxyl groups and hydroxyl groups in addition to unsaturated bonds such as (meth)acryloyl groups.

[0045] Examples of monomers having an epoxy group and an unsaturated bond such as a (meth)acryloyl group include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate. Among these, glycidyl (meth)acrylate is preferred from the viewpoint of reactivity. The number of epoxy groups in the monomer having an epoxy group and an unsaturated bond such as a (meth)acryloyl group is preferably one or less per molecule. Examples of the monomer having an isocyanate group and an unsaturated bond such as a (meth)acryloyl group include Karenz MOI and AOI (Resonac Corporation).

[0046] The (meth)acrylic resin (a1) may contain structural units derived from other monomers copolymerizable with (meth)acrylic acid alkyl esters and functional group-containing monomers. Examples include monomers having an alkyleneoxy group and other vinyl monomers. Examples include methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, and acrylamide. The structural units derived from the other monomers preferably account for 0.1 to 20% by mass of 100% by mass of the monomers constituting the (meth)acrylic resin (a1).

[0047] The (meth)acrylic resin (a1) can be obtained by polymerizing the aforementioned (meth)acrylic monomer mixture. During polymerization, a polymerization initiator can be used, if necessary. The amount of the polymerization initiator is, for example, 0.01 to 10 parts by mass per 100 parts by mass of the monomer mixture. The polymerization method is not limited. For example, polymerization can be performed by solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization, with solution polymerization being most preferred due to ease of polymerization control. Examples of solvents used in solution polymerization include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, anisole, cyclohexanone, and isopropyl alcohol. The polymerization temperature can be, for example, 60 to 120°C, and the polymerization time can be approximately 2 to 12 hours.

[0048] The polymerization initiator is preferably a radical polymerization initiator. Suitable radical polymerization initiators are peroxides and azo compounds. Any of the thermal radical polymerization initiators described below can be used, and specifically, 2,2'-azobisisobutyronitrile (abbreviation: AIBN) is preferred.

[0049] [Urethane resin (a2)] In the present disclosure, the urethane resin (a2) is a compound containing two or more urethane bonds in one molecule. The urethane resin can be obtained by reacting a polyisocyanate with a polyol. The polyisocyanate may be any polyisocyanate having two or more isocyanate groups per molecule. From the viewpoint of dispersibility of the colorant (C), diisocyanates or triisocyanates are preferred, with diisocyanates being more preferred. The diisocyanate may be appropriately selected from known aliphatic diisocyanates such as hexamethylene diisocyanate and known aromatic diisocyanates such as benzene-1,3-diisocyanate. Furthermore, an isocyanate-terminated prepolymer obtained by reacting a polyol with an excess of polyisocyanate may be used as an intermediate for the urethane resin. The polyol may be any polyol having two or more hydroxyl groups per molecule, and from the viewpoint of dispersibility of the colorant (C), a diol or triol is preferred, with a diol being more preferred. The diol may be appropriately selected from known aliphatic diols such as ethylene glycol and known aromatic diols such as benzenediol. Prepolymers such as polyether polyols, polyester polyols, and polycarbonate polyols may also be used.

[0050] The urethane resin (a2) may be a polyurethane urea resin further having a urea bond. The polyurethane urea resin can be synthesized, for example, by reacting a urethane resin having an isocyanate group at its terminal with a polyamine. The polyamine may be any polyamine having two or more amino groups in one molecule, and from the viewpoint of dispersibility of the colorant (C), a diamine or triamine is preferred, and a diamine is more preferred. The diamine may be appropriately selected from known aliphatic diamines such as ethylenediamine and known aromatic diamines such as phenylenediamine.

[0051] From the viewpoint of dispersibility of the colorant (C), the urethane resin (a2) preferably further has a radically polymerizable functional group such as a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, an unsaturated carboxylic acid group, etc. as a functional group, and more preferably has a (meth)acryloyl group. Specifically, the (meth)acryloyl group can be introduced by addition reaction of the above-mentioned polyol, diisocyanate, or triisocyanate with an acrylate having a hydroxyl group.

[0052] [Epoxy resin (a3)] In the present disclosure, the epoxy resin (a3) ​​is a compound having two or more epoxy groups in one molecule. The epoxy resin (a3) ​​also includes compounds having a functional group added thereto. The functional group preferably includes a radical polymerizable functional group such as a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, or an unsaturated carboxylic acid group, and more preferably includes a (meth)acryloyl group. Regarding the properties of the epoxy resin (a3), the use of a liquid form can improve adhesion, while the use of a solid form can improve film-forming properties of the resin composition layer. Preferred examples of the epoxy resin (a3) ​​include glycidyl ether type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, alicyclic (cycloaliphatic) epoxy resins, bisphenol type epoxy resins, hydrogenated bisphenol type epoxy resins, etc. Furthermore, from the viewpoint of adhesion, the epoxy resin (a3) ​​is more preferably a bisphenol type epoxy resin or a high-purity hydrogenated epoxy resin. As a compound in which a radically polymerizable functional group is added as a functional group to one or more epoxy groups, bisphenol A type diglycidyl ether diacrylate is preferred.

[0053] Examples of glycidyl ether type epoxy resins include cresol novolac type epoxy resins, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane. Examples of the glycidylamine type epoxy resin include tetraglycidyldiaminodiphenylmethane and tetraglycidylmetaxylylenediamine. Examples of the glycidyl ester type epoxy resin include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate. Examples of cyclic aliphatic (alicyclic) epoxy resins include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis(epoxycyclohexyl)adipate, and the like. Examples of bisphenol-type epoxy resins include bisphenol A-type epoxy resins, bisphenol F-type epoxy crosslinkers, bisphenol S-type epoxy resins, bisphenol AD-type epoxy resins, etc. Bisphenol A-type epoxy resins are particularly preferred from the viewpoint of adhesion. Examples of hydrogenated bisphenol epoxy resins include hydrogenated bisphenol A epoxy resins, hydrogenated bisphenol F epoxy resins, etc. In particular, hydrogenated bisphenol A epoxy resins are preferred from the viewpoint of adhesion.

[0054] [Polymerization initiator (B)] In this embodiment, either a thermal polymerization initiator or a photopolymerization initiator can be used, and it is preferable to use a thermal polymerization initiator from the viewpoint of the film-forming property and adhesion of the resin composition layer. When either a thermal polymerization initiator or a photopolymerization initiator is used, it is preferable that the resin (A) has one or more radically polymerizable functional groups per molecule as functional groups. Examples of the radically polymerizable functional group include a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, and an allyl group, and a (meth)acryloyl group is preferred.

[0055] In the present embodiment, a thermal radical polymerization initiator or a thermal cationic polymerization initiator can be used as the thermal polymerization initiator. From the viewpoint of storage stability of the resin composition layer, a thermal radical polymerization initiator is preferred. The thermal radical polymerization initiator has a function of generating radicals by heat, and examples of the thermal radical polymerization initiator include organic peroxide polymerization initiators and azo thermal polymerization initiators.

[0056] Examples of the organic peroxide polymerization initiator include: Dialkyl peroxides such as diacetyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)hexane, and (2-ethylhexanoyl)(t-butyl)peroxide; Dipropionyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, bis(3,5,5-trimethylhexanoyl)peroxide, 1,1,3,3-tetramethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, Peroxy esters such as t-butylperoxyisobutyrate, di-t-butylperoxyhexahydroterephthalate, 1,1,3,3-tetramethylbutylperoxy-3,5,5-trimethylhexanate, t-amylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, dibutylperoxytrimethyladipate, 2,5-dimethyl-2,5-di-2-ethylhexanoylperoxyhexane, t-hexylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, and t-butylperoxy-2-ethylhexyl monocarbonate; Ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, t-butyl benzoate, and pivaloyl t-butyl peroxide; Peroxyketals such as 2,2-bis(t-butylperoxy)butane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, and 4,4-bis(t-butylperoxy)butylpentanoate; Hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and p-menthane hydroperoxide; diacyl peroxides such as dibenzoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, diisobutyryl peroxide, bis-3,5,5-trimethylhexanol peroxide, m-toluylbenzoyl peroxide, succinic acid peroxide, and 2,4-dichlorobenzoyl peroxide; Examples of peroxydicarbonates include, but are not limited to, peroxydicarbonates such as bis(t-butylcyclohexyl)peroxydicarbonate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, di-2-ethylhexyl peroxycarbonate, di-sec-butyl peroxycarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-amylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, and 6-bis(t-butylperoxycarboxyloxy)hexane. From the viewpoint of storage stability, dialkyl peroxides are preferred, and di-t-butyl peroxide is more preferred.

[0057] Examples of the azo thermal polymerization initiator include: 2,2'-azobisbutyronitriles such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobisvaleronitrile such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile); 1,1'-azobis-1-alkanenitriles such as 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobispropionitriles such as 2,2'-azobis(2-hydroxymethylpropionitrile); 2,2'-azobispropionamides such as 2,2'-azobis(N-butyl-2-methylpropionamide) and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); Other examples include dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], and 1-[(1-cyano-1-methylethyl)azo]formamide. Examples of azo compounds having a carboxyl group or a hydroxyl group include, but are not limited to, 4,4'-azibis(4-cyanopentanoic acid), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), and 2,2'-azobis(N-(carboxyethyl)-2-methylpropionamidine) tetrahydrate. From the viewpoint of storage stability, 2,2'-azobispropionamides are preferred, and 2,2'-azobis(N-butyl-2-methylpropionamide) is more preferred.

[0058] The 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 60 to 200° C., more preferably 80 to 180° C., even more preferably 100 to 150° C., and most preferably 105 to 130° C. By setting the temperature to 60° C. or higher, the storage stability of the resin composition layer can be improved, and by setting the temperature to 200° C. or lower, the heat aging step for the sealing layer can be shortened.

[0059] The 10-hour half-life temperature is the temperature at which the thermal polymerization initiator is thermally decomposed and reduced to half of its initial value after 10 hours. Specifically, a thermal polymerization initiator solution is prepared using a solvent inert to the radicals of the thermal polymerization initiator, and sealed in a nitrogen-purged glass tube. This is immersed in a thermostatic chamber set at a specified temperature for 10 hours to cause thermal decomposition, and the amount of remaining thermal polymerization initiator is measured. This series of steps is carried out at several temperatures, and the half-life can be calculated from the straight line obtained by plotting.

[0060] The content of the thermal radical polymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and even more preferably 0.1 to 8% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, adhesion can be suitably adjusted.

[0061] Among thermal polymerization initiators, thermal cationic polymerization initiators have the function of generating ions by heat. Examples of the cationic component of thermal cationic polymerization initiators include sulfonium cations, quaternary ammonium cations, and iodonium cations. Examples of the anionic component include antimony hexafluoride anions, phosphorus hexafluoride anions, tetrakis(pentafluorophenyl)borate anions, and trifluoromethanesulfonic acid.

[0062] Examples of the photopolymerization initiator include triazine-based photopolymerization initiators, borate-based photopolymerization initiators, carbazole-based photopolymerization initiators, acetophenone-based photopolymerization initiators, and oxime ester-based photopolymerization initiators. The acetophenone-based photopolymerization initiators and oxime ester-based photopolymerization initiators are preferred because they are less likely to yellow during the heat aging process. From the viewpoint of preventing yellowing, the content of the photopolymerization 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.

[0063] [Colorant (C)], [Dispersion (D)] The colorant (C) may be any of inorganic pigments, organic pigments, and dyes, and may be mixed to obtain a desired color. The color is not particularly limited, but black is preferred from the viewpoint of light-blocking properties, and white is preferred from the viewpoint of reflection properties. To achieve a black color, multiple pigments can be subtractively mixed to form a mixed colorant. Black pigments are preferred from the viewpoint of dispersibility. By using black pigments to make the resin composition layer black and sealing the spaces between and around multiple micro LEDs, the sealing layer functions as a black matrix (light-shielding layer), making the light emitted by the micro LEDs appear more vivid. Examples of black pigments include carbon black, carbon nanotubes (CNT), perylene black, titanium black, iron black, aniline black, chromium iron oxide, etc. From the viewpoint of adhesion, carbon black is preferred.

[0064] Carbon blacks used in the present disclosure include channel black, furnace black, Known carbon blacks such as black, thermal black, lamp black, acetylene black, and ketjen black can be used. Specific examples of carbon black include "Raven 3500, 1180, 1080 Ultra, 1060 Ultra, 1040" manufactured by Birla Carbon Corporation, "TOKABLACK #8300, #7360SB" manufactured by Tokai Carbon Co., Ltd., "Special Black 350, 250, 100, 550, 5, 4, 4A, 6", "Nipex 160IQ, 170IQ", "Printex U, V, 140U, 140V, 95, 90, 85, 80, 75, 55, 45, P, 60, L6, L, 300, 30, 3, 35, 25, A, G" and "ColorBlack FW200, FW2, S170" manufactured by Orion Engineered Carbons, and "REGAL 400R, 330R, 250R" and "MOGUL" manufactured by Cabot Corporation. E, L," "MONARCH1300, 280," and Mitsubishi Chemical Corporation's "MA7, 8, 11, 14, 77, 100, 100R, 100S, 220, 230," "#2650, #2600, #2350, #2300, #1000, #980, #970, #960, #950, #900, #850, #750B, #650B, #52, #47, #45, #45L, #44, #40, #33, #32, #30, #25, #20, #10, #5, #95," etc. From the viewpoint of dispersibility, carbon black should have a specific surface area of ​​50 to 400 m by the BET method. 2 / g, a volatile content of 0.1 to 10% by weight, and a pH value of 2 to 10 are preferred, with a pH of 3 to 8 being more preferred, and a pH of 3 to 6 being even more preferred.

[0065] When the purpose is to form a black matrix (light-shielding layer), the colorant (C) preferably has an average primary particle diameter (hereinafter referred to as particle diameter) of 10 to 100 nm. By making the particle diameter 10 nm or more, it is easy to maintain the viscosity of the resin composition at a level suitable for coating. Furthermore, by making the particle diameter 100 nm or less, the blackness is improved and high light-shielding performance is exhibited. Note that when the particle shape of the colorant (C) has an average aspect ratio (major axis length / minor axis length) of 1.5 or more, the particle diameter is determined by averaging the major axis lengths. The particle size of the colorant (C) can be determined from the average value of about 20 primary particles that can be observed in an image magnified about 50,000 to 1,000,000 times using a transmission electron microscope (TEM).

[0066] When the purpose is to form a black matrix (light-shielding layer), the content of the colorant (C) is preferably 5 to 45 mass %, more preferably 15 to 35 mass %, and even more preferably 20 to 30 mass %, based on the total amount (100 mass %) of the light-shielding layer. By setting the content of the colorant (C) within the above range, an excellent level of light-shielding property is achieved.

[0067] When the purpose is to form a reflective layer, for example, titanium oxide, zinc oxide, lithopone, etc. can be used as the colorant (C). From the viewpoint of whiteness, a white pigment is preferred, and among them, titanium oxide is preferred from the viewpoint of dispersibility. By using a white pigment to make the resin composition layer white and sealing the spaces between and around multiple micro LEDs, the sealing layer functions as a reflective layer, and the brightness of the micro LEDs can be further increased.

[0068] As the titanium oxide used in the present disclosure, known titanium oxides such as rutile titanium oxide and anatase titanium oxide can be used. From the viewpoint of deterioration of resins due to light, rutile titanium oxide is preferred. Specific examples of rutile titanium dioxide include "Tipake R-820, R-830, R-930, R-550, R-630, R-680, R-670, R-680, R-670, R-780, R-850, CR-50, CR-57, CR-80, CR-90, 90-2, CR-93, CR-95, CR-97, CR-63, CR-58, UT771" manufactured by Ishihara Sangyo Kaisha, Ltd., "Tipure R-101, R-103, R-104, R-105, R-108, R-900, R-902+, R-960, R-706" manufactured by DuPont, and "TITONE" manufactured by Sakai Chemical Industry Co., Ltd. Examples include R-25, R-21, R-32, R-7E, R-5N, R-62N, R-42, R-45M, GTR-100, and D-918.

[0069] The average particle size of the rutile titanium oxide is preferably 0.1 μm or more and 0.9 μm or less, and more preferably 0.2 μm or more and 0.7 μm or less. By setting the particle size to 0.1 μm or more, it is easy to prevent aggregation and sedimentation of titanium oxide in the coating liquid for forming the resin composition layer. Furthermore, by setting the particle size to 0.9 μm or less, whiteness is improved and high reflectivity is achieved. When the particle shape of the colorant (C) has an average aspect ratio (major axis length / minor axis length) of 1.5 or more, the particle size is determined by averaging the major axis lengths. The particle size of the colorant (C) can be determined from the average value of approximately 20 primary particles observed in an image magnified approximately 50,000 to 1,000,000 times using a transmission electron microscope (TEM).

[0070] It is preferable to disperse the colorant (C) in the resin (A) and use it as a dispersion (D) from the viewpoint of adjusting the film-forming property and light-blocking property of the resin composition layer. The dispersing machine used for mechanical disintegration in the dispersion process may be any commonly used dispersing machine, such as a ball mill, a roll mill, a sand mill, a bead mill, or a Nanomizer. Among these, a bead mill is preferably used. Examples of such machines include a Super Mill, a sand grinder, an agitator mill, a grain mill, a Dyno Mill, a pearl mill, and a Cobol Mill (all trade names).

[0071] In the present disclosure, from the viewpoint of storage stability of the dispersion, it is preferable to use a dispersant in the dispersion treatment of the colorant (C). In the present disclosure, the dispersant has the function of imparting repulsive force between particles so that the particles divided through the above-mentioned dispersion treatment do not re-aggregate. As the dispersant, a conventionally known compound can be used, and examples thereof include cationic, anionic, or nonionic surfactants, cationic, anionic, or nonionic polymer dispersants, and pigment derivative dispersants. From the viewpoint of storage stability of the dispersion, pigment derivative dispersants are preferred.

[0072] Pigment derivative dispersants are compounds that contain acidic, basic, or neutral groups in the organic pigment residue. Examples include compounds with acidic substituents such as sulfo, carboxyl, or phosphate groups, as well as amine salts of these, compounds with basic substituents such as sulfonamide, amide, or terminal tertiary amino groups, and compounds with neutral substituents such as phenyl or phthalimidoalkyl groups. Examples of organic pigments include phthalocyanine pigments, diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiazine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, threne pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo. By using these pigment dispersants, it becomes possible to prevent aggregation of the colorant (C) contained in the resin composition over time and to maintain good light-blocking properties.

[0073] The content of the pigment dispersant (total content when two or more types are included) 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. When the pigment dispersant is contained in an amount of 0.01 mass % or more, the light-blocking properties are improved, and when the content is 10 mass % or less, the viscosity of the black resin composition for forming the sealing layer falls within a suitable range, resulting in good coating suitability.

[0074] [Crosslinker (E)] The resin composition layer of the present disclosure may contain a crosslinking agent (E). The crosslinking agent (E) crosslinks with the reactive functional groups of the resin (A) during heat pressing or heat aging in the pressing process, thereby increasing the cohesive strength of the resin composition layer and improving adhesion. The crosslinking agent (E) has a plurality of functional groups that can react with the functional groups of the resin (A). Examples of the crosslinking agent (E) include known compounds such as acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, amine compounds, and compounds having an epoxy group. The loss tangent (tanδ) of the resin composition layer can be calculated by the following formula:100 From the viewpoint of adjusting the amount of the copolymer, an isocyanate compound, a compound having an epoxy group, an aziridine compound, or an imidazole compound is preferred.

[0075] The isocyanate compound is an isocyanate having two or more isocyanate groups. When the resin (A) has a hydroxyl group or an amino group, it can react with the isocyanate group. The isocyanate compound is preferably, for example, an isocyanate monomer such as an aromatic polyisocyanate, an aliphatic polyisocyanate, an araliphatic polyisocyanate, or an alicyclic polyisocyanate, as well as a biuret, a nurate, or an adduct thereof. The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure, and more preferably an adduct or nurate, which is a reaction product of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. Examples of the adducts include a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, and a trimethylolpropane adduct of isophorone diisocyanate. Examples of the nurates include a nurate of hexamethylene diisocyanate, a nurate of tolylene diisocyanate, and a nurate of isophorone diisocyanate, with a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, and a trimethylolpropane adduct of isophorone diisocyanate being more preferred.

[0076] When the resin (A) has a carboxy group, a compound having an epoxy group can be suitably used as the crosslinking agent (E). Preferred examples of the compound having an epoxy group include glycidyl ether-type epoxy compounds, glycidyl amine-type epoxy compounds, glycidyl ester-type epoxy compounds, and alicyclic (cycloaliphatic) epoxy compounds.

[0077] Examples of glycidyl ether type epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, bisphenol AD ​​type epoxy compounds, cresol novolac type epoxy compounds, phenol novolac type epoxy compounds, α-naphthol novolac type epoxy compounds, bisphenol A type novolac type epoxy compounds, dicyclopentadiene type epoxy compounds, tetrabromobisphenol A type epoxy compounds, brominated phenol novolac type epoxy compounds, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane.

[0078] Examples of the glycidylamine type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, triglycidyl meta-aminophenol, and tetraglycidyl meta-xylylenediamine.

[0079] Examples of the glycidyl ester type epoxy compound include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.

[0080] Examples of cyclic aliphatic (alicyclic) epoxy compounds include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis(epoxycyclohexyl)adipate, and the like.

[0081] Examples of the aziridine compound include trimethylolpropane tris[3-(aziridin-1-yl)propionate], tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane.

[0082] Imidazole compounds include 2-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, imidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[ Examples of the imidazole compounds include 2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole, as well as compounds with improved storage stability, such as imidazole compounds encapsulated in microcapsules.

[0083] The content of the crosslinking agent (E) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, adhesion can be suitably adjusted.

[0084] [Other ingredients] The resin composition layer of the present disclosure may contain other components as long as they do not impair the objectives of the present disclosure. For example, silane coupling agents, monomers, inorganic fillers, surface conditioning additives, curing accelerators, curing retarders, softeners, antistatic agents, lubricants, antiblocking agents, adhesion improvers, etc. may be added. It is preferable to include a silane coupling agent in order to improve adhesion to the glass substrate on which the micro LED is mounted. Furthermore, when the resin (A) has a polymerizable unsaturated bond, it may contain a monomer that contributes to the formation of the sealing layer.

[0085] A silane coupling agent is a compound in which a hydrolyzable group such as a methoxy group or an ethoxy group and a functional group such as an epoxy group are bonded to a silicon atom via an alkylene group. Examples of silane coupling agents include: alkoxysilane compounds having a (meth)acryloxy group, such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxypropyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; Alkoxysilane compounds having a vinyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; alkoxysilane compounds having an amino group, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; alkoxysilane compounds having a mercapto group, such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane; Alkoxysilane compounds having one epoxy group, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxy tetraalkoxysilane compounds such as silane; Examples include 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, hexamethyldisilazane, and silicone resins having alkoxysilyl groups in the molecule. From the viewpoint of adhesion, an alkoxysilane compound is preferred, and 3-glycidoxypropyltrimethoxysilane is more preferred. When a resin (A) having a polymerizable unsaturated bond is used, an alkoxysilane compound having a (meth)acryloxy group is preferably used.

[0086] [monomer] In the present embodiment, a monomer refers to a compound having a radically polymerizable functional group, which is the minimum structural unit for constituting a polymer. Examples of radically polymerizable functional groups include a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, and an allyl group. The monomer may be a monofunctional monomer or a polyfunctional monomer. In this specification, "monofunctional" refers to a compound having only one radically polymerizable functional group per molecule, and "bifunctional" and "trifunctional" refer to compounds having two and three radically polymerizable functional groups per molecule, respectively. In this specification, bifunctional or higher functional compounds are also collectively referred to as "polyfunctional." By including a monomer, the film-forming properties of the resin composition layer can be adjusted, and adhesion can be improved.

[0087] Specific examples of the monomer include, but are not limited to, a monofunctional (meth)acrylate monomer having one (meth)acryloyl group in the molecule, a monofunctional vinyl monomer having one N-vinyl group in the molecule, a bifunctional (meth)acrylate monomer having two (meth)acryloyl groups in the molecule, a bifunctional (meth)acrylate monomer having one (meth)acryloyl group and one allyl group in the molecule, a trifunctional (meth)acrylate monomer having three (meth)acryloyl groups in the molecule, a tetrafunctional (meth)acrylate monomer having four acryloyl groups in the molecule, a pentafunctional (meth)acrylate monomer having five (meth)acryloyl groups in the molecule, and a hexafunctional (meth)acrylate monomer having six (meth)acryloyl groups in the molecule.

[0088] The content of the monomer can be in the range of 30% by mass or less, or 20% by mass or less, based on the total amount (100% by mass) of the resin composition layer, and when used, it is preferably in the range of 15% by mass or less. By setting the content in the above range, adhesion can be suitably adjusted.

[0089] Examples of inorganic fillers include inorganic compounds such as silica, alumina, magnesium hydroxide, barium sulfate, calcium carbonate, antimony trioxide, magnesium oxide, zirconium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorillonite, bentonite, boron nitride, aluminum nitride, titanium nitride, etc. Among these, titanium nitride, silica, and zirconium oxide are preferred from the viewpoint of coating film resistance to scratches.

[0090] The curing accelerator may be contained to adjust the crosslinking rate of the resin composition layer of the present disclosure. The curing accelerator is not particularly limited and can be selected appropriately. Specific examples of the curing accelerator include amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators.

[0091] As described above, the encapsulating sheet of the present disclosure has a resin composition layer for forming an encapsulating layer sandwiched between a first film and a second film, and it is important that the surface roughness Ra of the resin composition layer on the surface in contact with the first film is 0.02 μm or more, and is preferably 60% or less of the thickness Ta of the resin composition layer. In addition, the cut level difference Rδc of the contour curve of the resin composition layer on the surface in contact with the first film is preferably 0.05 to 20 μm. The following methods can be used to obtain a resin composition layer having a surface roughness Ra and a cut level difference Rδc of a contour curve within such ranges. For example, a method may be mentioned in which a coating liquid of a resin composition for forming a resin composition layer is applied onto a second film, followed by drying, and the surface of the resin composition layer formed on the second film is covered with a first film having a predetermined surface shape, or a coating liquid of a resin composition for forming a resin composition layer is applied onto a first film having a predetermined surface shape, followed by drying, and the surface of the resin composition layer formed on the first film is covered with a second film to obtain an encapsulating sheet, and then, in a step prior to the step shown in FIG. 2(a), the first film is peeled off, thereby inverting and transferring the surface shape of the first film onto the surface of the resin composition layer. Another method is to prepare a mold with a predetermined surface shape separately and press the mold against the surface of the resin composition layer formed on the second film, thereby inverting and transferring the predetermined surface shape to the surface of the resin composition layer. Alternatively, there may be mentioned a method in which fine particles or the like are collided with the surface of the resin composition layer formed on the second film, thereby directly forming the surface of the resin composition layer into a predetermined surface shape. The transfer method is preferred, and it is preferable to use a first film having a predetermined surface shape.

[0092] For coating, known coating machines and techniques can be used, such as a comma coater, die coater, roll coater, lip coater, reverse coater, gravure coater, bar coater, curtain coater, dip coating, spin coating, silk screen, casting, etc. The solvent contained in the resin composition can be removed by a drying step after coating, and the amount of the solvent can be adjusted to adjust the viscosity of the coating liquid or the film thickness after drying. In a preferred embodiment, the resin composition is applied to a support such as a first film or a second film, and the coating film is then heated and dried using a hot air oven, an infrared heater, or the like, to form a resin composition layer on one side of the support. Furthermore, to increase the crosslink density of the resin composition layer, it is preferable to perform an aging treatment, such as leaving the film to stand under specific temperature conditions, or to irradiate it with UV or the like. After coating, the resin composition may be transferred to another support such as a first film, a second film, or a substrate using a laminator.

[0093] [First Film] The first film is not particularly limited, and examples thereof include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polypropylene and polyethylene, and plastic films such as polyvinyl chloride films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, and cycloolefin films. From the viewpoint of handling, polyester films and polyolefin films are preferred.

[0094] The first film has a release layer on the surface facing the resin composition layer, which is preferably formed by applying a release agent such as a silicone resin, an alkyd resin, a fluororesin, or a melamine resin to the film, and from the viewpoint of handling (prevention of separation), a release layer using a silicone resin is more preferred. First film peeling force P l is preferably 0.1 to 15 gf / 20 mm, more preferably 0.3 to 10 gf / 20 mm, and even more preferably 0.5 to 5 gf / 20 mm. First film peeling force P l can be adjusted by the release treatment of the release layer. For example, it can be adjusted by the type of release agent, the amount of release agent applied, and the surface roughness of the release layer. If you want to reduce the release force value, it is effective to increase the surface roughness or the amount of release agent applied, and if you want to increase the release force value, you can adjust it in the opposite way. First film peeling force P l can be measured, for example, by attaching the second film of the sealing sheet to a SUS plate, and peeling the first film from the resin composition layer at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and a relative humidity of 50%. The first film may have a functional layer in addition to the release layer, such as an antistatic layer or an antiblocking layer.

[0095] First film thickness T l When a release layer or a functional layer is provided on the first film, the thickness T l is a value including the release layer and the functional layer. By setting the thickness in the above range, it is possible to prevent the waviness of the first film from being transferred to the resin composition layer, and to form a uniform resin composition layer. The first film preferably has a surface roughness Ra of 0.02 μm or more on the surface that will come into contact with the resin composition layer, and is 60% or less of the thickness Ta of the resin composition layer described below. Using a first film with a surface roughness Ra of 0.02 μm or more and inverting and transferring the surface roughness Ra to the surface of the resin composition layer prevents excessive adhesion of the resin composition layer to the surface of the micro LED during the process shown in FIG. 2(a), making it easier to correct the placement position. Furthermore, using a first film with a surface roughness Ra of 0.02 μm or more and inverting and transferring the surface roughness Ra to the surface of the resin composition layer during the process shown in FIG. 2(b) reduces the likelihood of air remaining at the interface between the substrate and the resin composition layer, resulting in a good appearance. That is, a resin composition layer with a surface roughness Ra of 0.02 μm or more is important in terms of suppressing and preventing blocking and air entrapment. A surface roughness of 0.03 μm or more is preferred, 0.1 μm or more is more preferred, and 0.3 μm or more is even more preferred.

[0096] In addition, the surface roughness Ra of the surface of the resin composition layer is preferably large in terms of suppressing and preventing blocking and air entrapment. On the other hand, in the process shown in Figure 2 (b), in terms of embedding ability and smoothness for sufficiently filling the spaces between and around the micro LEDs without gaps, it is preferable that the surface roughness Ra is not too large. When forming the resin composition layer by a transfer method, it is preferable to use a first film whose surface roughness Ra is 60% or less of the thickness Ta of the resin composition layer to be formed (before pressing), more preferably 50% or less, even more preferably 40% or less, and most preferably 20% or less.

[0097] The first film preferably has a profile cut level difference Rδc of 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.5 μm or more on the surface that will contact the resin composition layer, and preferably has a profile cut level difference Rδc of 20 μm or less, more preferably 10 μm or less, and even more preferably 6 μm or less.

[0098] [Second film] The second film is not particularly limited, and examples thereof include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polypropylene and polyethylene, and plastic films such as polyvinyl chloride films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, and cycloolefin films. From the viewpoint of handling, polyester films and polyolefin films are preferred. The second film is preferably laminated directly to the resin composition layer.

[0099] The second film preferably has a release layer on the surface facing the resin composition layer, which is preferably formed by applying a release agent such as a silicone resin, an alkyd resin, a fluororesin, or a melamine resin to the film, and from the viewpoint of handling (prevention of separation), a release layer using a silicone resin is more preferred. The peeling force P2 of the second film is preferably from 0.5 to 40 gf / 20 mm, more preferably from 0.8 to 30 gf / 20 mm, and even more preferably from 1.0 to 20 gf / 20 mm. The peel strength P2 of the second film can be adjusted by the release treatment of the release layer. For example, it can be adjusted by the type of release agent, the amount of release agent applied, and the surface roughness of the release layer. To reduce the peel strength, it is effective to increase the surface roughness or the amount of release agent applied. To increase the peel strength, the opposite can be done. The peel strength P2 of the second film is preferably greater than the peel strength P1 of the first film. Specifically, the value of P2 / P1 is more preferably 1.1 to 11, and even more preferably 1.1 to 6. The peel strength P2 of the second film can be measured, for example, by peeling the first film from the sealing sheet, attaching the exposed resin composition layer to a SUS plate, and then peeling the second film from the resin composition layer at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and a relative humidity of 50%. The second film may have a functional layer in addition to the release layer, such as an antistatic layer or an antiblocking layer. The thickness T2 of the second film is 12 to 188 μm, more preferably 12 to 100 μm, and even more preferably 20 to 60 μm. When a release layer or a functional layer is provided on the second film, the thickness T2 is a value including the release layer and the functional layer. By setting the thickness within the above range, the pressure applied to the resin composition layer in the pressing step described below is controlled, and the resin composition layer flows uniformly, resulting in good embeddability and adhesion. [Example]

[0100] Hereinafter, the present disclosure will be specifically described with reference to examples and comparative examples, but the present disclosure is not particularly limited to the examples. In the following description, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0101] Weight average molecular weight (Mw), solid content, thickness, loss modulus (G'') 100 The numerical values ​​obtained in this example, such as the above, were obtained by the following method.

[0102] [Weight average molecular weight (Mw)] The weight average molecular weight (Mw) was measured using a GPC "LC-GPC system" manufactured by Shimadzu Corporation, and was calculated by conversion using polystyrene of known molecular weight as a standard substance. Device name: Shimadzu Corporation, LC-GPC system "Prominence" Columns: Four GMHXL columns manufactured by Tosoh Corporation and one HXL-H column manufactured by Tosoh Corporation were connected together. Mobile phase solvent: tetrahydrofuran Flow rate: 1.0mL / min Column temperature: 40℃

[0103] [Solid content] The mass of the aluminum cup (W0) was measured using a precision balance. Next, approximately 1 g of sample was placed in the aluminum cup, and the mass of the sample in the aluminum cup (W1) was measured using a precision balance. The sample in the aluminum cup was heated in an oven at 150°C for 120 minutes, then removed from the oven and returned to room temperature. The residual mass (W2) of the sample in the aluminum cup after heating was measured using a precision balance. The solid content was then calculated using the formula (W2 - W0) / (W1 - W0) × 100 (%).

[0104] [Encapsulating sheet thickness T t , the thickness T of the resin composition layer a , thickness of the first film T1, thickness of the second film T2] Ten points are determined at equal intervals from one end to the other end of the encapsulating sheet cut into a size of 10 cm x 10 cm, and the thickness of the encapsulating sheet is measured at those ten points. The average value is taken as the thickness T of the encapsulating sheet. t Next, the first film was peeled off from the sealing sheet, and the thickness of the peeled first film was measured at 10 positions corresponding to the same positions as above. The average value was designated as T1. Thereafter, the second film was further peeled off from the resin composition layer, and the thickness of the peeled second film was measured at 10 positions corresponding to the same positions as above. The average value was designated as T2. The thickness T of the resin composition layer a is T a =T t The thickness was measured using a MH-15M (Nikon Corporation).

[0105] [Tg of resin composition layer, loss modulus (G'') at 100°C 100 ) and loss tangent (tanδ 100 )] Two sets of encapsulating sheets from which the first release sheet had been peeled were prepared, and the adhesive layers were bonded together using a laminator set to 90°C to create a laminate of second release sheet / resin composition layer / second release sheet. The second release sheet on one side of this laminate was peeled off, and the resin composition layers were sequentially bonded together to form a resin composition layer with a thickness of 1 mm. The loss modulus (G'') and loss tangent (tanδ) of this resin composition layer were measured using a rheometer (TA Instruments, DHR-2) with a φ8 mm measurement probe under conditions of 0.1% strain, 1 Hz frequency, and a heating rate of 3°C / min from -50°C to 150°C. The temperature at the peak top of the loss tangent (tan δ) was taken as Tg. If multiple peak tops were observed, the highest peak top was taken as Tg. Furthermore, the measured values ​​of loss modulus (G'') and loss tangent (tan δ) at a temperature of 100°C were read from the obtained data.

[0106] [Surface roughness Ra, cutting level difference of profile curve Rδc] The surface roughness Ra defined in the present invention is the arithmetic mean of the absolute values ​​of the deviations between the center line of a portion of measurement length L extracted from the roughness curve in the direction of its center line and the roughness curve. The cut level difference Rδc of the profile curve is the difference in height level that corresponds to any two load length ratios within the roughness curve, and in the present invention, the two load length ratios are defined as 25% and 75%. In this disclosure, the surface roughness Ra and the cut level difference Rδc of the profile curve are values ​​measured in accordance with JIS B0601: 2013. Specifically, measurement data is acquired using a laser microscope (Keyence Corporation, VK-X100), and the acquired measurement data is imported into analysis software (Keyence Corporation, analysis application "VK-H1XA" equipped with JIS B0601: 2013 surface texture measurement module "VK-H1XR"), and the JIS B0601: 2013 surface texture measurement is performed to calculate the surface roughness. In this disclosure, to obtain a roughness curve from a measured profile curve obtained by measurement, a λc profile filter was used, which removes short wavelengths such as noise, and a λs profile filter, which removes long wavelengths of waviness. Depending on the surface condition to be measured, one of the following settings was selected in the surface roughness measurement analysis application: λs profile filter 2.5 μm, λc profile filter 0.8 mm, λs profile filter 8 μm, λc profile filter 2.5 mm, or λs profile filter 25 μm, λc profile filter 8 mm, to measure the surface roughness Ra and the cut level difference Rδc of the profile.

[0107] <Production and preparation of resin (A)> [Preparation of (meth)acrylic resin (a1-1) solution] A reaction vessel (hereinafter simply referred to as the "reaction vessel") equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube was charged with 80 parts of ethyl acetate, 41 parts of methyl methacrylate, 58 parts of n-butyl methacrylate, 1 part of 4-hydroxybutyl acrylate, and 0.1 parts of 2,2'-azobisisobutyronitrile as an initiator, and the atmosphere inside the reaction vessel was replaced with nitrogen gas. The mixture was then heated to 75°C while stirring under a nitrogen atmosphere to initiate the reaction. The reaction solution was then reacted at 75°C for 4 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a solution of hydroxyl-containing (meth)acrylic resin (a1-1) with a weight-average molecular weight (Mw) of 100,000 and a solids content of approximately 25%.

[0108] [Production Example of (Meth)acrylic Resin (a1-2) Solution] After obtaining a solution of (meth)acrylic resin (a1-1), an equivalent amount of Karenz AOI (2-acryloyloxyethyl isocyanate, manufactured by Resonac Corporation) corresponding to half of the hydroxyl groups of the 4-hydroxybutyl acrylate used in the copolymerization was added as a modifier, and the mixture was stirred at 60°C for 24 hours. If necessary, the mixture was diluted with ethyl acetate to obtain a solution of (meth)acrylic resin (a1-2) having hydroxyl groups and methacryloyl groups (solid content: approximately 25%).

[0109] [Preparation of (meth)acrylic resin (a1-3) solution] According to the monomer composition shown in Table 1, a solution of (meth)acrylic resin (a1-3) having hydroxyl groups with a weight average molecular weight (Mw) of 100,000 and a solid content of approximately 25% was obtained in the same manner as in the case of the solution of (meth)acrylic resin (a1-1).

[0110] [Production Example of (Meth)acrylic Resin (a1-4) Solution] After obtaining a solution of (meth)acrylic resin (a1-3), an equivalent amount of Karenz AOI (2-acryloyloxyethyl isocyanate, manufactured by Resonac Corporation) corresponding to half of the hydroxyl groups of the 4-hydroxybutyl acrylate used in the copolymerization was added as a modifier, and the mixture was stirred at 60°C for 24 hours. If necessary, the mixture was diluted with ethyl acetate to obtain a solution of (meth)acrylic resin (a1-4) having hydroxyl groups and methacryloyl groups (solid content: approximately 25%).

[0111] [Production Example of Solutions of (Meth)acrylic Resins (a1-5) to (a1-10)] Using the monomer compositions and modifiers shown in Table 1, solutions of (meth)acrylic resins (a1-5) to (a1-10) having hydroxyl groups and methacryloyl groups (solid content: approximately 25%) were obtained in the same manner as for the solution of (meth)acrylic resin (a1-4).

[0112] [Production Example of (Meth)acrylic Resin (a1-11) Solution] As shown in Table 1, the amounts of monomers blended were 14 parts n-butyl acrylate, 84 parts n-butyl methacrylate, and 2 parts acrylic acid, and a solution of (meth)acrylic resin (a1-11) having a carboxy group with a weight average molecular weight (Mw) of 100,000 and a solid content of approximately 25% was obtained by a method similar to that for producing (meth)acrylic resin (a1-1).

[0113] [Production Example of (Meth)acrylic Resin (a1-12) Solution] After obtaining a solution of (meth)acrylic resin (a1-11), an equivalent amount of glycidyl methacrylate corresponding to half the amount of carboxy groups of the acrylic acid subjected to copolymerization was added, and the mixture was stirred at 60°C for 24 hours, and diluted with ethyl acetate as necessary to obtain a solution of (meth)acrylic resin (a1-12) having carboxy groups and methacryloyl groups (solid content: approximately 25%).

[0114] [Production Examples of (Meth)acrylic Resin (a1-13) to (a1-15) Solutions] Using the monomer compositions and modifiers shown in Table 1, solutions of (meth)acrylic resins (a1-13) to (a1-15) having carboxy groups and methacryloyl groups (solid content: approximately 25%) were obtained in the same manner as for the solution of (meth)acrylic resin (a1-12).

[0115] [Table 1]

[0116] The symbols in the table are as follows: MMA: methyl methacrylate nBMA: n-butyl methacrylate nBA: n-butyl acrylate iBMA: i-butyl methacrylate 4HBA: 4-hydroxybutyl acrylate 2HEA: 2-hydroxyethyl acrylate AA: acrylic acid GMA: Glycidyl methacrylate

[0117] [Example of preparing a solution of urethane resin (a2)] A solution (solid content: approximately 25%) of polyurethane resin "VA-9320" (manufactured by Toyochem Co., Ltd.) with an acid value of 10 mgKOH / g was prepared.

[0118] [Example of preparing a solution of epoxy resin (a3)] Teisan Resin SG-80H (manufactured by Nagase ChemteX Corporation) with a weight average molecular weight (Mw) of 350,000 was diluted with ethyl acetate to prepare a solution of epoxy resin (a3) ​​with a solid content of approximately 25%.

[0119] [Example 1] <Production of Liquid Resin Composition for Forming Sealing Layer> 380 parts of a solution containing 95 parts of the aforementioned (meth)acrylic resin (a1-2) as resin (A) and 5 parts of (B-1) di-t-amyl peroxide (Luperox DTA, manufactured by Arkema Yoshitomi Co., Ltd.) as a polymerization initiator were stirred in a disper, and then filtered through a membrane filter with a pore size of 10 μm to remove coarse foreign matter that could cause coating unevenness, thereby obtaining a liquid resin composition 1.

[0120] <Production of encapsulating sheets> The liquid resin composition 1 was applied onto the release layer of a 50 μm thick second film, SP-PET-O3-BU (manufactured by Mitsui Chemicals Tocello Co., Ltd.), so that the thickness after drying would be 30 μm, and the coating was dried in a hot air oven at 100°C for 3 minutes to form a resin composition layer. Next, the release layer side of Cosmo Peel E7001 (manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm, a surface roughness Ra of 0.04 μm on the release layer side, and Rδc of 0.06 μm was bonded to the exposed resin composition layer, and aging was performed at 4°C for 7 days to obtain a transparent encapsulating sheet of Example 1 in which the first film / transparent resin composition layer / second film were laminated in this order, and the transparent encapsulating sheet was evaluated according to the method described below. The surface of the resin composition layer exposed by peeling off the first film had a surface roughness Ra of 0.06 μm and Rδc of 0.09 μm. The resin composition layer in the produced encapsulating sheet had a Tg of 75°C and a tanδ 100 is 0.91, G'' 100 is 3.2 x 10 5 It was Pa.

[0121] [Examples 2 to 8], [Comparative Example 1] As shown in Table 2, encapsulating sheets were produced and evaluated in the same manner as in Example 1, except that the following films were used as the first film. Note that the resin compositions for forming the encapsulating layer shown in Table 2 indicate solid contents. KOBATECH RF 40TLGN (Kobayashi Co., Ltd.), thickness 40 μm, Ra: 0.14 μm, Rδc: 0.21 μm KOBATECH RF 40TLSN (Kobayashi Co., Ltd.), thickness 40 μm, Ra: 0.31 μm, Rδc: 0.50 μm KOBATECH RF 40TLMN (Kobayashi Co., Ltd.), thickness 40 μm, Ra: 1.10 μm, Rδc: 1.52 μm Cosmo Peel E7002 (manufactured by Toyobo Co., Ltd.), thickness 50 μm, Ra: 0.01 μm, Rδc: 0.03 μm PG7H (manufactured by Godo Resin Industries Co., Ltd.), thickness 50 μm, Ra: 2.73 μm, Rδc: 4.41 μm PG15H (manufactured by Godo Resin Industries Co., Ltd.), thickness 50 μm, Ra: 3.80 μm, Rδc: 6.29 μm PG12H (manufactured by Godo Resin Industries Co., Ltd.), thickness 50 μm, Ra: 10.49 μm, Rδc: 14.31 μm

[0122] [Examples 9 to 38], [Comparative Examples 2 to 3] Encapsulating sheets were prepared in the same manner as in Example 1 except that the resin (A), the initiator (B), the crosslinking agent (E), and the first film were changed as shown in Tables 3 to 5, and were evaluated in the same manner. In addition, Example 10 in Table 3 is a re-recording of Example 1, and Example 19 in Table 4 is a re-recording of Example 4.

[0123] [Examples 39 to 41] As shown in Table 6, PG12H (manufactured by Godo Resin Industries Co., Ltd.) was used as the first film, the same coating liquid as in Example 11 was used as the resin composition for forming the sealing layer, and the thickness of the resin composition layer for forming the sealing layer was 100 μm, 50 μm, or 30 μm. Except for this, sealing sheets were obtained in the same manner as in Example 1 and evaluated in the same manner.

[0124] The abbreviations in the table are as follows: <Polymerization initiator (B)> (B-1): Di-t-amyl peroxide (Luperox DTA, manufactured by Arkema Yoshitomi Co., Ltd.) (B-2): 2,2'-azobis(N-butyl-2-methylpropionamide) (Vam-110, Fujifilm Wako Pure Chemical Industries, Ltd.) <Crosslinking agent (E)> (E-1): Isocyanate compound (Cosmonate T100, manufactured by Mitsui Fine Chemicals, Inc.) (E-2): Aziridine compound (Chemitite PZ-33, manufactured by Nippon Shokubai Co., Ltd.) (E-3): Dicyandiamide compound (jER Cure DICY8, manufactured by Mitsubishi Chemical Corporation)

[0125] [Table 2]

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

[0129] [Table 6]

[0130] <Production of Dispersion (D) of Colorant (C)> [Production Example of Dispersion (D-1) of Colorant (C)] 2,400 parts of a solution of resin (a1-12) (solid content approximately 25%), 800 parts of (C-1) carbon black MA100 (manufactured by Mitsubishi Chemical Corporation) as a colorant, and 800 parts of methyl ethyl ketone (hereinafter referred to as MEK) as a dispersion medium were mixed and pre-dispersed using a disperser. After that, the main dispersion was carried out for 2 hours using a 0.6 L Dyno Mill filled with 1,800 g of zirconia beads with a diameter of 1.0 mm, to obtain a dispersion (D-1) with a solid content of approximately 35%.

[0131] [Production Examples of Dispersions (D-2) to (D-4) of Colorant (C)] Dispersions (D-2) to (D-4) with a solid content of approximately 35% were obtained in the same manner as for dispersion (D-1), except that 2400 parts of the solution of resin (a1-13), the solution of resin (a1-14), and the solution of resin (a1-15) were each used in an amount of 2400 parts instead of 2400 parts of the solution of resin (a1-12).

[0132] [Production Example of Dispersion (D-5) of Colorant (C)] Dispersion (D-5) with a solid content of approximately 35% was obtained in the same manner as dispersion (D-1), except that (C-2) metal oxide pigment Black 6340 (manufactured by Asahi Chemical Industry Co., Ltd.) was used as the colorant instead of (C-1).

[0133] [Production Example of Dispersion (D-6) of Colorant (C)] Dispersion (D-6) with a solid content of approximately 35% was obtained in the same manner as dispersion (D-1), except that (C-3) metal oxide pigment Typepaque CR-97 (manufactured by Ishihara Sangyo Kaisha) was used as the colorant instead of (C-1).

[0134] [Example 101] <Production of Liquid Black Resin Composition for Forming Black Sealing Layer> 240 parts of a solution containing 60 parts of resin (a1-12), 100 parts of a dispersion (D-1) containing 20 parts of colorant (C-1), 15 parts of resin (a1-12), and 65 parts of a dispersion medium, and 5 parts of a polymerization initiator (B-1) di-t-amyl peroxide were stirred in a disperser, and then filtered through a membrane filter with a pore size of 10 μm to remove coarse foreign matter that could cause coating unevenness, thereby obtaining liquid resin composition 101.

[0135] <Production of black encapsulating sheet> An encapsulating sheet was obtained in the same manner as in Example 1, except that the liquid black resin composition 101 was used instead of the liquid resin composition 1 used in Example 1, and was evaluated in the same manner.

[0136] [Examples 102 to 108], [Comparative Example 101] As in Examples 1 to 8 and Comparative Example 1, except that the first film was changed as shown in Table 7, an encapsulating sheet was obtained in the same manner as in Example 101, and evaluated in the same manner.

[0137] [Examples 109 to 122] An encapsulating sheet was prepared in the same manner as in Example 101, except that the resin (A), dispersion (D), initiator (B), crosslinking agent (E), and first film were changed as shown in Tables 8 to 9, and evaluated in the same manner. In addition, Example 110 in Table 8 is a re-recording of Example 101, and Example 117 in Table 9 is a re-recording of Example 104.

[0138] [Examples 123 to 125] As shown in Table 10, PG12H (manufactured by Godo Resin Industries Co., Ltd.) was used as the first film, a coating liquid containing resin (a1-15) / colorant (C-1) / initiator (B-1) = 75 / 20 / 5 (parts by mass) was used as the resin composition for forming the sealing layer, and the thickness of the resin composition layer for forming the sealing layer was 100 μm, 50 μm, or 30 μm. Except for this, sealing sheets were obtained in the same manner as in Example 101 and evaluated in the same manner.

[0139] [Table 7]

[0140] [Table 8]

[0141] [Table 9]

[0142] [Table 10]

[0143] [evaluation] <Blocking resistance> As shown in Figure 5(a), two metal rods 9 each measuring 20 mm x 20 mm x 60 mm were attached in parallel to a metal plate 8 measuring 100 mm x 100 mm x 1 mm with a 25 mm gap between them using double-sided adhesive tape (not shown). The encapsulating sheet was cut into a size of 50 mm x 50 mm, and the first film was peeled off to expose the resin composition layer, thereby obtaining a laminate 2' of the second film and the resin composition layer. As shown in Figure 5(b), the laminate 2' was rolled up and inserted between metal rods 9 attached in parallel to a metal plate 8, with the resin composition layer facing upward, so that the top of the upper surface of the laminate 2' was higher than the two metal rods 9, and placed so that both ends of the laminate 2' were in contact with the upper surface of the metal plate 8. Thereafter, as shown in Fig. 5(c), a glass plate 10 having a size of 80 mm x 80 mm was placed so as to be in contact with the resin composition layer and the upper surfaces of the two metal rods 9. Fig. 5(d) is a schematic diagram of the placed state as seen from the glass plate 10 side. The resin composition layer was visually observed from the outside of the placed glass plate 10 (the upper part of FIG. 5(c)), and blocking resistance was evaluated based on the presence or absence of interference fringes. ◯: No interference fringes were observed. ×: Interference fringes were observed.

[0144] <Air release> A glass plate measuring 200 mm x 120 mm was prepared. The encapsulating sheet was cut to a size of 200 mm x 120 mm, the first film was peeled off to expose the resin composition layer, and the resin composition layer was placed on the first surface of the glass plate. Then, a 50 μm thick TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tocello Co., Ltd.) and a 2 mm thick PVC film (Celeb T, manufactured by Okamoto Co., Ltd.) were placed on the second film as cushioning materials, in that order, and cardboard was then placed on top to prevent adhesion. The laminate consisting of glass plate / resin composition layer / second film / cushioning material (TPX / PVC film) / cardboard was pressed against the substrate surface from above at 3 MPa and 100°C for 10 minutes, thereby adhering the resin composition layer to the glass plate. After pressing, the cushioning material and cardboard were peeled off. By visually observing an arbitrary 80 mm x 80 mm area from the second surface side of the obtained sealing layer and the glass plate with the second film, the air release property was evaluated based on the maximum diameter of poor adhesion areas occurring at the interface between the resin composition layer and the glass plate. ◎: The maximum diameter of the gap is less than 3 mm. 〇: The maximum diameter of the gap is 3mm or more and less than 10mm. △: The maximum diameter of the gap is 10 mm or more and less than 20 mm. ×: The maximum diameter of the gap is less than 20 mm.

[0145] <Smoothness> For the sealing layer and the glass plate with the second film used in the air release property evaluation, extremely small voids at the interface between the glass plate and the resin composition layer were observed from the glass plate side using a laser microscope. The surface roughness Ra value was calculated using values ​​measured in accordance with JIS B0601:2013, and the smoothness of the interface between the resin composition layer and the glass plate was evaluated. ◎: Surface roughness Ra is less than 0.02 μm. ◯: Surface roughness Ra is 0.02 μm or more and less than 0.1 μm. △: Surface roughness Ra is 0.1 μm or more and less than 0.5 μm. ×: Surface roughness Ra is 0.5 μm or more.

[0146] <Embeddability> A test substrate (a 25mm x 25mm glass plate with multiple 200μm wide recesses and 5μm high protrusions formed in a grid pattern on one side) was prepared to mimic the unevenness of a micro LED substrate. A schematic cross-sectional view of the test substrate is shown in Figure 3. The encapsulating sheet was cut to a size of 30 mm x 30 mm, the first film was peeled off to expose the resin composition layer, and the resin composition layer was placed on the surface of the test substrate on which the concave and convex portions were formed. Then, a 50 μm thick TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tocello Co., Ltd.) and a 2 mm thick PVC film (Celeb T, manufactured by Okamoto Co., Ltd.) were placed on the second film as cushioning materials, in that order, and cardboard was then placed on top to prevent sticking. The laminate consisting of the glass substrate / resin composition layer / second film / cushioning material (TPX / PVC film) / cardboard was pressed against the substrate surface from above at 3 MPa and 100°C for 10 minutes, filling the recesses of the test substrate with the resin composition layer to form an encapsulating layer. After pressing, the cushioning material and cardboard were peeled off. Four corners of 15 randomly selected recesses (60 locations in total) of the resulting test substrate with the sealing layer and second film were observed from the glass plate side with a microscope, and the embeddability was evaluated based on the number of locations where gaps occurred. ◎: There are 56 or more areas with no gaps. 〇: There are 41 or more and 55 or fewer gap-free areas. △: 29 or more and 40 or less recesses without gaps. ×: There are 28 or fewer recesses without gaps. [Explanation of symbols]

[0147] 1: Encapsulating sheet 2: Resin composition layer 2': Laminate (the first film 3 is peeled off from the sealing sheet 1) 3: First film 4: Second film 5: Light emitting element 6: Circuit board 7: Glass substrate 8:Metal plate 9: Metal rod 10: Glass plate

Claims

1. A sealing sheet for sealing spaces between light-emitting elements for a display using a plurality of light-emitting elements as a light source, The encapsulating sheet includes a first film, a resin composition layer for forming an encapsulating layer, and a second film arranged in this order, The surface roughness Ra of the resin composition layer on the surface in contact with the first film is 0.02 μm or more, The resin composition layer has a glass transition temperature of 20°C or higher, and a loss tangent (tanδ) at 100°C, which is measured by dynamic viscoelasticity measurement in a torsion mode at a frequency of 1 Hz. 100 ) is 0.2 or more, Sealing sheet.

2. Loss tangent (tanδ) at 100°C 100 2. The encapsulating sheet according to claim 1, wherein the tensile strength (Tb) of the encapsulating sheet is 2.5 or less.

3. 3. The encapsulating sheet according to claim 1, wherein a cut level difference Rδc of a contour curve of the resin composition layer on a surface in contact with the first film is 0.05 to 20 μm.

4. The loss modulus (G″) of the resin composition layer at 100° C. obtained by dynamic viscoelasticity measurement at a frequency of 1 Hz 100 ) is 5 x 10 ３ Pa ~ 2 x 10 ７ The encapsulating sheet according to claim 3, wherein the tensile strength is 1000 ppm or less.

5. The encapsulating sheet according to claim 4, wherein the resin composition layer has a thickness Ta of 1 to 100 μm.

6. A display panel having an encapsulating layer comprising the resin composition layer of the encapsulating sheet according to claim 1 or 2.

7. A method for manufacturing a display panel, comprising the following steps (1) to (6): (1) a step of preparing the encapsulating sheet according to claim 1 or 2, in which a first film, a resin composition layer for forming an encapsulating layer, and a second film are arranged in this order; (2) preparing an object to be sealed, the object having a plurality of light-emitting elements arranged at intervals on one surface of a substrate; (3) peeling the first film from the encapsulating sheet to expose the resin composition layer for forming the encapsulating layer; (4) contacting the exposed resin composition layer for forming a sealing layer with the light-emitting surfaces of the plurality of light-emitting elements; (5) filling spaces between the plurality of light-emitting elements with a resin composition layer for forming a sealing layer; (6) Peeling off the second film.

Images