Sealing material sheet for self-luminous display or direct-lit backlight, self-luminous display, and direct-lit backlight

Abstract

An object is to provide a "sealing material sheet for self-luminous display or direct-lit backlight" that has a preferable level of moldability as a "sealing material sheet for self-luminous display or direct-lit backlight" and also has a high heat resistance that can withstand use in a particularly high-temperature environment. 【Solution means】A sealing material sheet 1 for a self-luminous display or a direct-lit backlight is made by using an olefin resin as a base resin, having a melting point of 45°C or higher and 60°C or lower, containing a crosslinking agent in a proportion of 0.1% by mass or more and 1.2% by mass or less in the resin component, and having a gel fraction of 50% or more and 90% or less after crosslinking treatment.

Description

Technical Field

[0001] The present invention relates to a sealing material sheet for a self-luminous display or a direct-lit backlight, a self-luminous display, and a direct-lit backlight.

Background Art

[0002] As a next-generation display device, the development of a self-luminous display typified by a micro LED TV is in progress. In such a self-luminous display, a sealing material sheet for protecting a light-emitting element is laminated on the surface on the light-emitting surface side of a surface light source device such as an LED module in which a light-emitting element such as an LED element is mounted on a wiring board (see Patent Document 1). And, in parallel with the development of these self-luminous displays, the development of a sealing material sheet excellent in suitability for a self-luminous display or a direct-lit backlight is also in progress (see Patent Document 2).

[0003] Here, the "sealing material sheet for a self-luminous display or a direct-lit backlight" disclosed in Patent Document 2 specifies the Vicat softening point of the base resin in a higher temperature range than that of a conventional sealing material sheet for an electronic device, and moreover, regarding the MFR of the resin, it is maintained in the same or lower low MFR range as before. Thereby, this sealing material sheet is considered to be at a preferable level for use in a self-luminous display or a direct-lit backlight in terms of performance such as moldability (followability to unevenness on the mounting surface) during hot press processing and film thickness uniformity after hot press processing.

[0004] Here, since the above-described sealing material sheet disclosed in Patent Document 2 uses a thermoplastic resin excellent in moldability as the base resin, a resin having a high melting point of about 90°C is used as the base resin in order to ensure the required heat resistance.

[0005] However, in the case of a display device composed of a self-emitting display or a direct-lit backlight, for example, when used for a display installed inside a vehicle exposed to direct sunlight, in addition to the increase in ambient temperature during use, the heat generation amount of the display itself increases with the increase in brightness, and it is assumed that the temperature inside the housing may reach about 90°C. In that case, the "sealing material sheet for self-emitting display or direct-lit backlight" requires even higher heat resistance. However, in the case of a sealing material sheet based on the above-mentioned thermoplastic resin, even if the base resin is a resin with a high melting point (about 90°C) as described above, it has been recognized as a new problem that the heat resistance may be insufficient. In addition, when assuming the use of a thermoplastic resin, it was difficult to use a resin with a high melting point exceeding 90°C in order to maintain the moldability during thermo-press processing.

[0006] Therefore, in order to impart heat resistance to the "sealing material sheet for self-emitting display or direct-lit backlight" that can withstand the above-mentioned extremely high temperature environment, it is conceivable to use a so-called thermally crosslinked sealing material sheet in which a crosslinking agent is previously contained in the sealing material composition used as the base resin, and crosslinking proceeds during integration as a self-emitting display or the like.

[0007] In this way, in the newly developed "thermally crosslinked sealing material sheet for self-emitting display or direct-lit backlight", due to the progress of crosslinking during the modularization stage, it is possible to impart high heat resistance to the final product that can withstand use in the above-mentioned harsh high temperature environment. And in such a "thermally crosslinked sealing material sheet", a resin with a low melting point of about 50°C can be used as the base resin. As a result, it is possible to form a sealing material sheet while surely suppressing the progress of crosslinking in the film-forming stage, and moreover, it is possible to obtain a sealing material sheet with excellent moldability.

[0008] However, in the process of developing a sealing material sheet for a self-luminous display or a direct-lit backlight using a heat-crosslinkable resin with a low melting point (about 50°C) as described above, among a group of sealing material sheets manufactured using a resin with the same type of base resin (for example, low-density polyethylene resin) and melting point (for example, 50°C), the inventors have come to recognize as a new problem that some have sufficient heat resistance to withstand use in the above-described particularly high-temperature environment, while others have insufficient heat resistance.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a sealing material sheet having a preferable level of moldability as a sealing material sheet for a self-luminous display or a direct-lit backlight, and further having a high heat resistance that can withstand use in a particularly high-temperature environment.

Means for Solving the Problems

[0011] As a result of intensive research, the inventors of the present invention have found that when the "sealing material sheet for a self-luminous display or a direct-lit backlight" is a sealing material sheet based on a heat-crosslinkable resin with a low melting point, by limiting the base resin to a resin in which the temperature difference between the supplementary melting start temperature and the melting point is a predetermined value or less, the above problems can be solved, and the present invention has been completed. Specifically, the present invention provides the following.

[0012] (1) A sealing material sheet for a self-luminous display or a direct-lit backlight, which uses an olefin resin as a base resin, has a melting point of 45°C or higher and 60°C or lower, and a temperature difference between the supplementary melting start temperature and the melting point of 11°C or lower, and contains a crosslinking agent in a proportion of 0.1% by mass or more and 1.2% by mass or less in the resin component.

[0013] According to the sealing material sheet of (1), it has a preferable level of moldability as a sealing material sheet for a self-luminous display or a direct-lit backlight, such as moldability, and moreover, it has a high heat resistance that can withstand use even in a particularly high-temperature environment, and a "sealing material sheet for a self-luminous display or a direct-lit backlight" can be obtained.

[0014] (2) The sealing material sheet according to (1), a display surface panel, and a plurality of light-emitting elements are mounted on a wiring board to form a light-emitting module, and the sealing material sheet covers the light-emitting elements and the wiring board and is laminated on the light-emitting module, and the display surface panel is laminated on the sealing material sheet, which is a self-luminous display.

[0015] According to the self-luminous display of (2), by enjoying the above-mentioned advantageous effects exhibited by the "sealing material sheet" of (1) and having a high heat resistance that can withstand use even in a particularly high-temperature environment, a self-luminous display that exhibits excellent durability in a high-temperature environment can be obtained.

[0016] (3) The self-luminous display according to (3), wherein the gel fraction of the sealing material sheet is 50% or more and 90% or less.

[0017] According to the self-luminous display of (3), by enjoying the above-mentioned advantageous effects exhibited by the self-luminous display of (2) and more stably exhibiting a high heat resistance that can withstand use even in a particularly high-temperature environment, a self-luminous display that exhibits excellent durability in a high-temperature environment can be obtained.

[0018] (4) The light-emitting element is an LED element, the width and depth of the LED element are both 300 μm or less, the height is 200 μm or less, and the arrangement interval between the LED elements is 0.03 mm or more and 100 mm or less. The self-luminous display according to (2) or (3).

[0019] The self-luminous display of (4) is an embodiment in which the self-luminous display of (2) or (3) is applied to various high-definition LED display devices such as a "dot matrix display device" in which a large number of LED elements (LED chips) are directly mounted on a substrate by a chip-on-board method. According to this, by enjoying the above-mentioned advantageous effects exhibited by the self-luminous display of (2) or (3) and having a high heat resistance that can withstand use in a particularly high-temperature environment, a high-definition LED display device that exhibits excellent durability in a high-temperature environment can be obtained.

[0020] (5) The light-emitting element is an LED element, the width and depth of the LED element are both 50 μm or less, the height is 10 μm or less, and the arrangement interval between the LED elements is 0.005 mm or more and 5 mm or less. The self-luminous display according to (2) or (3).

[0021] The self-luminous display of (5) is an embodiment in which the self-luminous display of (2) or (3) is applied to various ultra-high-definition LED display devices such as a "micro LED TV" expected as a next-generation video display device. According to this, by enjoying the above-mentioned advantageous effects exhibited by the self-luminous display of (2) or (3) and having a high heat resistance that can withstand use in a particularly high-temperature environment, an ultra-high-definition LED display device that exhibits excellent durability in a high-temperature environment can be obtained.

[0022] (6) A direct-type backlight including a sealing material sheet according to (1) or (2) and a plurality of light-emitting elements mounted on a wiring substrate, wherein the sealing material sheet covers the light-emitting elements and the wiring substrate and is laminated on the light-emitting module.

[0023] According to the direct - type backlight of (6), by having a high heat resistance that can withstand use in a particularly high - temperature environment while enjoying the above - mentioned advantageous effects exerted by the "sealing - material sheet" of (1) or (2), a direct - type backlight that exhibits excellent durability in a high - temperature environment can be obtained.

[0024] (7) A liquid - crystal display device comprising the direct - type backlight described in (6), a diffusion plate, and a display - surface panel, wherein the diffusion plate is laminated on the sealing - material sheet constituting the direct - type backlight.

[0025] (7) The liquid - crystal display device is an embodiment of the present invention as a liquid - crystal display device using the direct - type backlight of (6) as a surface - light - source device. According to this, a liquid - crystal display device that exhibits excellent durability in a high - temperature environment can be obtained while enjoying the above - mentioned effects exerted by the direct - type backlight of (6).

Advantages of the Invention

[0026] According to the present invention, a "sealing - material sheet for a self - emitting display or a direct - type backlight", a "self - emitting display", a "direct - type backlight", and a "liquid - crystal display device" can be obtained, which have a preferable level of moldability as a sealing - material sheet for a self - emitting display or a direct - type backlight and also have a high heat resistance that can withstand use in a particularly high - temperature environment.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0028] <Self - emissive display> In this specification, the "self - emissive display" includes a display surface panel and a surface light source device composed of a light - emitting module in which a large number of minute light - emitting elements (such as LED elements) are mounted on a wiring board, and is an information display device that displays visual information such as characters, images, and moving images. The above - mentioned various visual information can be displayed on the display surface panel by selectively blinking the above - mentioned light - emitting elements (such as LED elements) by a light - emission control means. It generally refers to all information display devices. Specific examples of the "self - emissive display" include a "dot matrix display device" in which a large number of LED elements (LED chips) are directly mounted on a substrate by a chip - on - board method, and the above - mentioned "micro - LED TV", etc.

[0029] In addition, in this specification, a self-luminous display in which "LED elements of a minute size" or "LED elements of an extremely minute size", such as a "dot matrix display device" or a "micro LED television", are arranged in a matrix at a pitch of about 0.005 mm or more and 5 mm or less and in a number of about 1000 × 1000 or more is also generically referred to as a "micro LED display device". In this specification, with regard to the size of the LED element, an LED element in which both the width (W) and the depth (D) exceed 50 μm and are 300 μm or less, and the height (H) exceeds 10 μm and is 200 μm or less is referred to as an "LED element of a minute size", and with regard to the same size, an LED element in which both the width (W) and the depth (D) are 50 μm or less and the height (H) is 10 μm or less is referred to as an "LED element of an extremely minute size" (see FIG. 3). In addition, when the LED element has a configuration including an LED light-emitting chip and a resin cover covering the same, the size of the above-described LED element refers to the size of the entire light-emitting element including the resin cover.

[0030] Hereinafter, while exemplifying an embodiment in the case where the "self-luminous display" of the present invention is implemented as a "micro LED display device" as a preferred example of the embodiments of the present invention, a detailed description of the present invention will be given. However, the technical scope of the present invention is not limited to the embodiment as the "micro LED display device". The present invention is a technology that can be applied not only to the "micro LED display device" but also to the entire "self-luminous display" according to the above definition.

[0031] FIG. 1 is a front view of a micro LED display device 100 which is an example of an embodiment of the self-luminous display of the present invention, and a partial enlarged view (100A) thereof. Further, FIG. 2 is a cross-sectional view showing a cross-section of the A-A portion of FIG. 1, and is a drawing for explaining the layer configuration of the micro LED display device 100 shown in FIG. 1. As shown in FIGS. 1 and 2, this micro LED display device 100 includes an LED module 30 in which a large number of LED elements 10 are mounted on a wiring substrate 20 and function as a surface light source device, and a display surface panel 2.

[0032] [LED Module] The LED module 30 is a light-emitting module in the micro-LED display device 100. As shown in FIG. 2, in the LED module 30, the LED element 10 is mounted on the wiring portion 22 of the wiring substrate 20 in a conductive manner via the solder layer 23 with respect to the wiring substrate 20. Also, in the LED module 30, the light emission of each LED element 10 is individually controlled by a light emission control means (not shown) such as an IC chip substrate that is separately joined.

[0033] In the LED module 30, the encapsulant sheet 1 is laminated on the mounting surface of the LED element 10 in a manner of covering the LED element 10. And in the micro-LED display device 100, as this encapsulant sheet 1, the "encapsulant sheet for self-emitting display or direct-lit backlight" of the present invention is used. Details of the "encapsulant sheet for self-emitting display or direct-lit backlight" of the present invention will be described separately later.

[0034] Also, in the micro-LED display device 100, a display surface panel 2 such as various optical films and transparent protective glass is further laminated on the outer surface side of the encapsulant sheet 1 (the display surface side in the micro-LED display device 100).

[0035] (Wiring Substrate) As the support substrate 21 constituting the wiring substrate 20 in the LED module 30, a conventionally known glass epoxy-based rigid substrate as a substrate for an electronic circuit can be used. Alternatively, as the support substrate 21, a resin film having flexibility such as polyethylene terephthalate, polyimide, polyethylene naphthalate, etc. can be used to make the wiring substrate 20 a flexible substrate. Also, in any of the above cases, the wiring portion 22 can be formed of a metal such as copper or various other conductive members.

[0036] (LED Element) The LED element 10 is a light-emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. Structures have been proposed in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element, and a structure in which both a P-type and an N-type electrode are provided on one side of the element. Any of these LED elements can be used as the light-emitting element of the micro-LED display device 100. As an example, in the "self-emitting display" of the present invention, the LED element disclosed as a "chip-shaped electronic component" in Japanese Patent Application Laid-Open No. 2006-339551 can be preferably used. The LED element disclosed in this document is said to have dimensions of width × depth × height of approximately 25 μm × 15 μm × 2.5 μm (corresponding to the "LED element of extremely small size" in the present invention).

[0037] The LED element 10 used in the LED module 30 includes at least an LED light-emitting chip 11. It may also include a resin cover 12 that covers it. When the LED element 10 includes a resin cover 12, an organic insulating material such as an epoxy resin, a silicone resin, or a polyimide resin is used as the material of the resin cover 12. Among these, an epoxy resin is particularly preferably used. The resin cover 12 formed of an epoxy resin not only simply protects the LED light-emitting chip 11 from physical impact but also plays a role in suppressing total internal reflection of light into the semiconductor due to the difference in refractive index between the semiconductor constituting the LED light-emitting chip 11 and air, thereby increasing the light emission efficiency of the LED element 10. Incidentally, the "sealing material sheet for a self-emitting display or a direct-lit backlight" (sealing material sheet 1) of the present invention is formed of an olefin-based resin that is also excellent in adhesion to an epoxy resin, as will be described later. Therefore, it can be particularly preferably used as a sealing material sheet to be mounted on a micro-LED display device 100 configured using the LED element 10 including the resin cover 12 formed of an epoxy resin.

[0038] In the LED module 30, a "micro-sized LED element" can preferably be used. In this case, the arrangement interval of the "micro-sized LED element" is preferably 0.03 mm or more and 100 mm or less. The mounting mode of this "micro-sized LED element" is specifically also the standard mounting mode of the LED element in a "dot matrix display device".

[0039] Also, when a "miniature-sized LED element" is used in the LED module 30, the arrangement interval of this "miniature-sized LED element" is preferably 0.005 mm or more and 5 mm or less. The mounting mode of this "miniature-sized LED element" is specifically also the standard mounting mode of the LED element in a "micro LED TV".

[0040] There is no particular limitation on the overall size of the LED module 30. However, those with a diagonal length of 50 inches or more and 200 inches or less are considered preferable from the perspective of cost performance. However, by arranging and tiling a plurality of LED modules 30 in a matrix on the same plane, the light-emitting surface of a micro LED display device (self-emitting display body) can also be configured. A display display body formed by coupling a plurality of such LED modules by tiling is naturally included in the technical scope of the present invention. For example, an LED module 30 with a diagonal length of 6 inches can be joined 100×100 pieces vertically and horizontally to form a large micro LED display device with a diagonal length of 600 inches.

[0041] [Manufacturing method of self-emitting display body] An example of an embodiment of the self-luminous display of the present invention, a micro-LED display device 100, is formed by laminating an LED module 30 for a self-luminous display, a sealing material sheet 1, and other optical members arranged as needed, and through a process of integrating this laminate by hot press processing, and then further laminating and integrating a display surface panel 2 to this laminate by adhesion or the like. Incidentally, the "process of integrating the laminate by hot press processing" can specifically be carried out by various known methods such as a roll lamination method or a vacuum lamination method.

[0042] In the above manufacturing method, the sealing material sheet 1 is laminated in a manner that exhibits sufficient moldability in the above "process of integrating the laminate by hot press processing" to appropriately cover the LED element, and at the same time, the crosslinking of the uncrosslinked sealing material sheet 1 is also sufficiently advanced in parallel during the hot press processing, so that the micro-LED display device 100 can be made into a self-luminous display with extremely high heat resistance. Incidentally, as a separate process from the above "process of integrating the laminate by hot press processing", a manufacturing method in which a "heating process (curing process) for sufficiently advancing the crosslinking of the sealing material sheet" is carried out after the above hot press processing can also be used to manufacture a self-luminous display.

[0043] In the manufacturing method of the self-luminous display of the present invention, the heating conditions (heating time, heating temperature, etc.) in the above hot press processing or the above heating process (curing process) are appropriately optimized so that the gel fraction of the sealing material sheet 1 is 50% or more and 90% or less, preferably 60% or more and 80% or less.

[0044] <Direct-lit backlight> As used herein, the "direct-lit backlight" is a light source unit that can be used as a light source for a liquid crystal display using the direct-lit backlight method. In the above liquid crystal display, it is a surface light source device that illuminates a display surface panel such as a liquid crystal display panel from the back side. The "liquid crystal display" using the direct-lit backlight method includes a display surface panel such as a liquid crystal display panel and a backlight that illuminates this display surface panel from the back side (see Fig. 4).

[0045] As an example of the "direct-lit backlight" of the present invention, the direct-lit backlight 200 shown in Fig. 5 can be cited. The direct-lit backlight 200 is a light-emitting module in which a plurality of LED elements 10 are mounted on a wiring substrate 20, and the "sealing material sheet for self-emitting display or direct-lit backlight (sealing material sheet 1)" of the present invention is laminated in a manner covering the LED elements 10 and the wiring substrate 20. Also, in the direct-lit backlight 200, an optical member such as a diffusion plate 3 may be further laminated on the LED element 10 via the sealing material sheet 1.

[0046] As shown in Fig. 5, in the wiring substrate 20 constituting the direct-lit backlight 200, usually, a wiring portion 22 is formed on a support substrate 21 via an adhesive layer 24. An insulating protective film 25 is formed on the support substrate 21 and the wiring portion 22, and further, a reflective layer 26 made of white resin or the like is laminated on the insulating protective film 25. Also, the LED element 10 composed of the LED light-emitting chip 11 and the light-diffusing lens 13 is mounted on the wiring portion 22 in a conductive manner via a solder layer 23.

[0047] [Manufacturing method of direct-lit backlight] An example of an embodiment of the direct - type backlight of the present invention, the direct - type backlight 200, can also be manufactured by laminating each component member including the sealing material sheet 1 and integrating this laminate by thermo - pressing. Incidentally, if necessary, it is preferable to join some of the laminated members in advance with an adhesive before the above - mentioned thermo - pressing. By sufficiently advancing the cross - linking of the sealing material sheet 1 (uncross - linked sealing material sheet 1) during thermo - pressing, a direct - type backlight 200 having extremely high heat resistance can be obtained. Incidentally, in the manufacture of the direct - type backlight 200, the manufacturing of the direct - type backlight can also be carried out by further providing a heating step (curing step) for cross - linking separately after thermo - pressing, in a procedure that sufficiently advances the cross - linking of the sealing material sheet 1.

[0048] [Liquid crystal display body] As an example of the "liquid crystal display body" of the present invention, the liquid crystal display body 300 shown in FIG. 4 can be cited. The liquid crystal display body 300 includes a display surface panel 2 such as a liquid crystal display panel, and a direct - type backlight 200 as a surface light source device that illuminates the display surface panel 2 from the back side. A diffusion plate 3 is disposed between the direct - type backlight 200 and the display surface panel 2. In the direct - type backlight 200, the "sealing material sheet for self - emitting display body or direct - type backlight (sealing material sheet 1)" of the present invention is laminated in a manner of covering the LED element 10 and the wiring board 20, and the diffusion plate 3 is laminated on the sealing material sheet 1.

[0049] <Sealing material sheet for self - emitting display body or direct - type backlight> The "sealing material sheet for self - emitting display body or direct - type backlight (hereinafter, also simply referred to as the 'sealing material sheet')" of the present invention is a resin sheet that can be preferably used as a sealing material sheet for covering and laminating LED elements on the wiring board of a surface light source device such as an LED module or a direct - type backlight, mainly to protect the minute and numerous LED elements mounted as light - emitting elements from physical impact in various "self - emitting display bodies" or "direct - type backlights".

[0050] Moreover, the "sealing material sheet" of the present invention can be particularly preferably used in various "self-luminous display bodies" or "direct-lit backlights", especially in "micro LED display devices" that use "micro-sized LED elements" as light-emitting elements. By directly mounting "micro-sized LED elements" on a wiring board in a chip-on-board method, a high-definition "dot matrix display device" can be configured. However, the "sealing material sheet" of the present invention can be preferably used as a sealing material sheet for this "dot matrix display device" among various "self-luminous display bodies".

[0051] Furthermore, the "sealing material sheet" of the present invention can be more preferably used in "micro LED display devices" and the like that use "ultra-small-sized LED elements" which are even smaller in size than the above-mentioned "micro-sized LED elements" as light-emitting elements among various "self-luminous display bodies" or "direct-lit backlights". By mounting "micro-sized LED elements" on a wiring board, a "micro LED TV" which is expected to become the mainstream of next-generation TVs can be configured. However, the "sealing material sheet" of the present invention can be preferably used as a sealing material sheet for this "micro LED TV" among various "self-luminous display bodies".

[0052] And the "sealing material sheet" of the present invention can be used as a sealing material sheet that covers and stacks a large number of minute LED elements in various "micro LED display devices" or various "liquid crystal display devices" equipped with "direct-lit backlights", so as to appropriately protect the LED elements and endow these "micro LED display devices" or "liquid crystal display devices" with special heat resistance that can withstand a harsh high-temperature environment of about 90 °C depending on the situation, for example, when installed inside an automobile.

[0053] The "sealing material sheet" of the present invention, which has the above advantages over the conventional "sealing material sheet for self-luminous display or direct-lit backlight", is a sheet-like member formed by forming a sealing material composition based on an olefin resin (details of this "sealing material composition" will be described separately later). And this "sealing material sheet" is in an uncrosslinked state with a gel fraction of 0% or more and 10% or less, preferably 0% gel fraction, as a single sheet product at the stage before integration (before modularization) as a "self-luminous display" or the like after film formation. In the present specification, unless otherwise specified, the "sealing material sheet" of the present invention refers to an uncrosslinked resin sheet at the stage of a single product before integration (before modularization) as a self-luminous display after film formation.

[0054] However, the "sealing material sheet" of the present invention is a thermally crosslinkable resin sheet in which crosslinking is assumed to proceed during any of the processes performed until it is integrated with other members such as an LED module and completed as a self-luminous display or a direct-lit backlight after film formation. For this reason, as will be described in detail later, the "sealing material sheet" contains a crosslinking agent in a proportion of 0.1% by mass or more and 1.2% by mass or less in the resin component, specifically. Details of the type and content of the crosslinking agent will be described separately later as an explanation of the sealing material composition.

[0055] And the "sealing material sheet" of the present invention preferably has a gel fraction of 50% or more and 90% or less, more preferably 60% or more and 80% or less, after crosslinking proceeds at the completed product stage as a self-luminous display or a direct-lit backlight.

[0056] Here, the "gel fraction (%)" in this specification refers to a value obtained by putting 1.0 g of the encapsulant sheet into a resin mesh, extracting it with xylene at 110°C for 12 hours, then taking out the entire resin mesh, drying it, weighing it, and comparing the mass before and after extraction to measure the ratio (mass %) of the remaining insoluble matter. Note that a gel fraction of 0% means that the above-mentioned remaining insoluble matter is substantially 0 and the cross-linking reaction has not substantially started. More specifically, "gel fraction 0%" means that there is no remaining insoluble matter at all, or the mass % of the remaining insoluble matter measured by an analytical balance is less than 0.05 mass %. Note that the above-mentioned remaining insoluble matter does not include pigment components or the like other than the resin component. When these mixtures other than the resin component are mixed in the remaining insoluble matter by the above test, for example, by separately measuring the content of these mixtures in the resin component in advance, the "gel fraction (%)" that should originally be obtained for the remaining insoluble matter derived from the resin component excluding these mixtures can be calculated.

[0057] And the "encapsulant sheet" of the present invention has a melting point of 45°C or higher and 60°C or lower, more preferably a melting point of 50°C or higher and 55°C or lower, and the temperature difference between the extrapolated melting start temperature and the melting point is 11°C or lower, more preferably the same temperature difference is 10°C or lower. By not only optimizing the melting point range of the thermal properties of the encapsulant sheet but also limiting the above temperature difference of the encapsulant sheet within the above specific range, the preferable properties regarding moldability and the like required for the encapsulant sheet for the self-luminous display body and the special heat resistance at the completed product stage when it becomes a self-luminous display body or a direct-lit backlight can be stably imparted together. Note that, for example, even in the case of a thermally crosslinkable encapsulant sheet with a melting point of 45°C or higher, if the temperature difference between the extrapolated melting start temperature and the melting point exceeds 11°C, sufficient heat resistance may not necessarily be exhibited after the crosslinking progresses at the completed product stage, and as shown in the examples later, it has been clarified by the research of the present inventors that if the temperature difference between the extrapolated melting start temperature and the melting point becomes larger than a certain value even with the same melting point, it also has an adverse effect on the moldability.

[0058] Here, the melting point of the encapsulant sheet in this specification refers to the melting peak temperature measured by differential scanning calorimetry (DSC) at the stage after the completion of sheet formation of the encapsulant sheet formed by a forming method such as extrusion melt molding, which is composed of a resin component and other additives, that is, at the stage of uncrosslinked after film formation. Also, the extrapolated melting start temperature of the encapsulant sheet refers to the value obtained in accordance with the method described in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics". Specifically, for the encapsulant sheet at the uncrosslinked stage after film formation, the melting peak temperature is determined by DSC, and the temperature at the intersection of the straight line obtained by extending the baseline on the low temperature side to the high temperature side and the tangent drawn at the point where the gradient becomes maximum on the low temperature side curve of the melting peak (when two or more overlapping melting peaks appear, the melting peak with the lower melting peak temperature) is defined as the extrapolated melting start temperature.

[0059] For example, in the graph of FIG. 6, the melting point and the extrapolated melting start temperature of the "encapsulant sheet for self-luminous display or direct-lit backlight (Example 1)" of the present invention are shown. The melting point of this "encapsulant sheet" is 51.0 °C, and the extrapolated melting start temperature is 41.7 °C. Therefore, the temperature difference between the extrapolated melting start temperature and the melting point is 9.3 °C.

[0060] Also, the melt mass flow rate (MFR) of the "encapsulant sheet" is preferably 10.0 g / 10 min or more and 40.0 g / 10 min or less, more preferably 10.0 g / 10 min or more and 30.0 g / 10 min or less, and most preferably 10.0 g / 10 min or more and 25.0 g / 10 min or less. By setting the MFR of the "encapsulant sheet" to 10.0 g / 10 min or more, an encapsulant sheet with excellent moldability can be obtained. Also, by setting this MFR to 40.0 g / 10 min or less, the uniformity of the film thickness of the crosslinked encapsulant sheet after thermal press processing for integration as a self-luminous display device or the like can be maintained at a high level.

[0061] As used herein, the "MFR" of the encapsulant sheet refers to the value measured under the conditions of 190°C and a load of 2.16 kg in accordance with JIS K7210 at the stage after the completion of sheet formation of the encapsulant sheet formed by a forming method such as extrusion melt forming, i.e., the MFR in the uncrosslinked state after film formation, which is composed of a resin component and other additives. In the case where the encapsulant sheet is a multilayer film, the measured value obtained by performing the above measurement while maintaining all the layers in the multilayer state where they are integrally laminated shall be taken as the MFR value of the multilayer encapsulant sheet.

[0062] When the "encapsulant sheet" is a multilayer film, within the range of satisfying the essential constituent requirements of the present invention, it is more preferable to have a layer structure with different MFRs for each layer. In this case, it is preferable to arrange the layer with a higher MFR as the skin layer on the outermost layer side. The encapsulant sheet of the present invention, even when it is a single-layer encapsulant sheet, has sufficiently preferable transparency, heat resistance, and appropriate flexibility. However, by arranging the layer with a relatively high MFR in this way on the outermost layer, as a thermally crosslinkable encapsulant sheet, while maintaining the above-mentioned preferable transparency and heat resistance, the adhesion and moldability can be further improved.

[0063] The thickness of the "sealing material sheet" of the present invention may be 3 μm or more and 1000 μm or less, and preferably 3 μm or more and 600 μm or less. If the thickness is 1000 μm or less, sufficient moldability can be exhibited in the "sealing material sheet" of the present invention. Specifically, during hot press processing in a state where the LED element is covered, the resin constituting the sealing material sheet can sufficiently wrap around the unevenness on the surface of the LED module to perform good lamination without gaps. For this reason, in the "sealing material sheet" of the present invention, for example, when the LED element is arranged occupying an area of 1 / 2 of the surface area covered by the sealing material sheet, by using a "sealing material sheet" having a thickness of about 1 / 2 of the height of the LED element, after integration as a self-luminous display body or a direct-lit backlight, these LED elements can be sufficiently protected from impact. On the other hand, as the lower limit of the thickness of the "sealing material sheet", in order to maintain the uniformity of the film, it is usually preferably at least 3 μm or more. However, for example, if the LED element to be covered is an "extremely small-sized LED element" with a height of 6 μm or less, an extremely thin "sealing material sheet" with a thickness of 3 μm can also be used to cover it. However, when the LED element to be covered is a "small-sized LED element" with a height of 10 μm or more, the thickness of the "sealing material sheet" is preferably 5 μm or more.

[0064] In addition, the "sealing material sheet" of the present invention may be a single-layer film, or may be a multilayer film composed of a core layer and skin layers arranged on both sides of the core layer. For example, in a sealing material sheet that is a multilayer film composed of 3 or more layers, the thickness of the outermost layer is 30 μm or more and 120 μm or less, and the ratio of the thickness of the intermediate layer composed of all layers other than the outermost layer to the thickness of the outermost layer is preferably in the range of outermost layer: intermediate layer: outermost layer = 1:3:1 to 1:8:1. By doing so, while maintaining preferable heat resistance as a whole for the sealing material sheet, preferable moldability can be exhibited in the outermost layer.

[0065] Furthermore, the "sealing material sheet" of the present invention can also be made into a "black sealing material sheet" having a black color tone by using a resin composition containing a black colorant as the "sealing material composition" and forming a film therefrom. For example, by using such a "black sealing material sheet" for a self-luminous display body configured to include a light-shielding layer, it is possible to improve the contrast by reducing the reflected light from the side of the wiring board, and to improve the display quality by preventing the light of adjacent LED elements from mixing. In addition, the layer structure of the self-luminous display body can be simplified, which can contribute to an improvement in productivity (see Japanese Patent Application Laid-Open No. 2022-103204). Details of additives such as coloring agents used when the "sealing material sheet" of the present invention is made into a "black sealing material sheet" will be described separately later as an explanation of the sealing material composition. Note that "black" in this specification means that the CIE color coordinates measured in accordance with JIS Z8701-1999 under a C light source and a viewing angle of 2 deg are such that -1.0 ≦ a * ≦ 2.5 and -1.0 ≦ b * ≦ 15.0, and for the L * value, 0 ≦ L * ≦ 50, which refers to a color tone in this range.

[0066] Furthermore, the "sealing material sheet" of the present invention can also be made into a "light-diffusing type sealing material sheet" that diffuses the light emitted from the LED element by using a resin composition containing a light diffusing agent as the "sealing material composition" and forming a film therefrom. Note that when the "sealing material sheet" has a multilayer structure, the diffusing agent may be included only in some layers. For example, by using such a "light-diffusing type sealing material sheet" for a direct-lit backlight, the distance between the wiring board and the LED element, which was conventionally ensured by a spacer, can be ensured by this "light-diffusing type sealing material sheet". Thus, it is possible to eliminate the need to provide a diffusion plate and realize a thinning of the direct-lit backlight (see Japanese Patent Application Laid-Open No. 2021-9807). Details of additives such as coloring agents used when the sealing material sheet of the present invention is made into a "light-diffusing type sealing material sheet" will be described separately later as an explanation of the sealing material composition.

[0067] [Sealing Material Composition] The sealing material composition (hereinafter also simply referred to as "sealing material composition") used in the production of the "sealing material sheet" of the present invention is a heat-crosslinkable resin composition based on a low-density olefin resin (preferably a polyethylene resin) and containing a crosslinking agent as an essential component. In this specification, the "base resin" refers to the resin having the largest content ratio among the resin components of the resin composition in the resin composition containing the base resin. When using a mixed resin of the same type of resin with different densities (for example, a plurality of polyethylenes with different densities respectively), the entire mixed resin is regarded as the base resin.

[0068] (Base resin) As long as the base resin of the "sealing material composition" forming the "sealing material sheet" of the present invention has a melting point of 45°C or higher and 60°C or lower, and the temperature difference between the supplementary melting start temperature and the melting point is within the range of 11°C or lower, various olefin resins can be widely selected. Among them, in addition to low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or metallocene-based linear low-density polyethylene (M-LLDPE), various polyethylene resins can be preferably used.

[0069] Moreover, among the above-mentioned various polyethylenes, linear low-density polyethylene (LLDPE) has a narrow crystalline distribution and uniform crystal sizes. Therefore, not only are there no large crystal sizes, but the crystallinity itself is low, and it is excellent in transparency when processed into a sheet as a sealing material sheet. Therefore, the "sealing material sheet" composed of the "sealing material composition" using this as the base resin can better prevent the decrease in power generation efficiency due to the attenuation of incident light to the solar cell element when arranged on the light-receiving surface side of the solar cell element in the self-luminous display body.

[0070] The density of the above-mentioned olefin resin used as the base resin of the "sealing material composition" is preferably 0.875 g / cm 3 or more and 0.900 g / cm 3 or less, more preferably 0.880 g / cm 3 or more and 0.890 g / cm 3More preferably, the density of the base resin of the encapsulant composition is 0.875 g / cm 3 or more, so that the heat resistance of the encapsulant sheet can be stably improved to a sufficient level. Also, by setting the density to 0.900 g / cm 3 or less, the adhesion of the "encapsulant sheet" to a wiring board or the like can be maintained at a sufficiently preferable level.

[0071] In addition, the "polyethylene-based resin" in this specification includes not only ordinary polyethylene obtained by polymerizing ethylene, but also resins obtained by polymerizing compounds having ethylenic unsaturated bonds such as α-olefins, resins obtained by copolymerizing a plurality of different compounds having ethylenic unsaturated bonds, and modified resins obtained by grafting another chemical species onto these resins.

[0072] Among them, a "silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as comonomers" can be preferably used as part of the base resin of the encapsulant composition. By using such a resin, sufficient strength adhesion can be obtained between the "encapsulant sheet" and other laminated members such as a glass protection substrate and a solar cell element.

[0073] The content of the ethylenically unsaturated silane compound when forming the copolymer of the α-olefin and the ethylenically unsaturated silane compound is preferably, for example, 0.001% by mass or more and 15% by mass or less, more preferably 0.01% by mass or more and 5% by mass or less, and most preferably 0.05% by mass or more and 2% by mass or less, based on the total copolymer mass.

[0074] (Crosslinking agent) Regarding the one-hour half-life temperature of the crosslinking agent used in the "encapsulant composition", it is preferable to use one having a temperature of 120°C or higher and 145°C or lower. Thereby, the "sealant composition" according to the present invention can be made into a composition capable of melt extrusion molding in the range of 110°C or lower.

[0075] Further, as specific examples of preferable crosslinking agents that satisfy the above conditions, peroxyketals such as n-butyl 4,4-di(t-butylperoxy)valerate, ethyl 3,3-di(t-butylperoxy)butyrate, 2,2-di(t-butylperoxy)butane, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-peroxy)hexyne-3 and other dialkyl peroxides can be preferably used as crosslinking agents to be added to the encapsulant composition.

[0076] The content of the above crosslinking agent in the "encapsulant composition" may be 0.2% by mass or more and 1.2% by mass or less, more preferably 0.4% by mass or more and 0.8% by mass or less, based on the base resin in the "encapsulant composition". By setting the content of the crosslinking agent within the above range, the "encapsulant sheet" of the present invention can be provided with excellent heat resistance. Incidentally, as described above, the encapsulant sheet of the present invention forms a film without substantial progress of crosslinking, and it is assumed that the content of the above crosslinking agent in the encapsulant sheet at the sheet stage after film formation is within the range of 0.1% by mass or more and 1.2% by mass or less.

[0077] (Crosslinking aid) The "encapsulant composition" preferably contains a polyfunctional monomer having a carbon-carbon double bond and / or an epoxy group, more preferably a crosslinking aid in which the functional group of the polyfunctional monomer is an allyl group, a (meth)acrylate group, or a vinyl group. This not only promotes an appropriate crosslinking reaction to improve the heat resistance of the "encapsulant sheet" to a high level, but also this crosslinking aid reduces the crystallinity of the base resin such as linear low-density polyethylene that forms the encapsulant sheet and maintains transparency. As a result, in addition to the effect of improving the heat resistance described above, the transparency of the "encapsulant sheet" can be made more excellent.

[0078] Examples of crosslinking aids that can be used in the "sealing material composition" specifically include polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate; poly(meth)acryloxy compounds such as trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylate; epoxy compounds such as glycidyl methacrylate containing a double bond and an epoxy group, 4-hydroxybutyl acrylate glycidyl ether, and 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and trimethylolpropane polyglycidyl ether containing two or more epoxy groups. These may be used alone or in combination of two or more. Among these crosslinking aids, TAIC, which has good compatibility with linear low-density polyethylene, significantly exhibits the effect of reducing crystallinity by crosslinking to maintain transparency and imparting flexibility at low temperatures, can be particularly preferably used. In addition, the content of the above crosslinking aid in the "sealing material composition" is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.05% by mass or more and 2.0% by mass or less, based on the base resin in the "sealing material composition".

[0079] [Other Additives] Other components can be further contained in the "sealing material composition". For example, hindered amine light stabilizers (HALS), ultraviolet absorbers, heat stabilizers, adhesion improvers, nucleating agents, dispersants, leveling agents, plasticizers, defoaming agents, flame retardants, and various other fillers can be appropriately added. Although the content ratios of these additives vary depending on their particle shapes, densities, etc., it is preferable that each is within the range of 0.001% by mass or more and 60% by mass or less in the "sealing material composition". By including these additives, stable mechanical strength over a long period, and effects such as prevention of yellowing and cracking can be imparted to the "sealing material composition".

[0080] (Black colorant) When the "sealing material sheet" of the present invention is made into a "black sealing material sheet", the black colorant used to impart an appropriate color tone to the resin sheet is preferably a pigment-based material. For example, carbon black, which is widely used as a black pigment, can be cited as an example of a preferable pigment. When coloring for display applications, it is often the case that a plurality of dyes are combined to express black. However, in that case, when the pressure becomes uneven during adhesive bonding, color unevenness is likely to occur. Also, in the case of dye-based materials, dye deterioration (fading deterioration) is likely to occur, so it is preferable to use a pigment-based material from the viewpoint of heat resistance. However, when it is necessary to lower the transmittance of a specific wavelength in order to expand the color tone range, it is also possible to use an appropriate amount of dye.

[0081] When carbon black is used as the above-mentioned black pigment, the content of carbon black in the resin component of the "black sealing material sheet" may be appropriately adjusted within the range of 0.0001% by mass or more and 50% by mass or less according to the thickness of the "black sealing material sheet" and the required color tone. When the thickness of the "black sealing material sheet" exceeds 500 μm, by setting the content of the above-mentioned carbon black to 0.0001% by mass or more, the necessary blackness can be expressed. Incidentally, when the thickness of the "black sealing material sheet" is 10 μm or less, the content of the above-mentioned carbon black may be adjusted within the range of 10% by mass or more and 50% by mass or less. By setting the content of carbon black within the above range, stable and sufficiently mottle-free coloring becomes possible.

[0082] Incidentally, when the "sealing material sheet" of the present invention is made into a "black sealing material sheet", it is more preferable to add a dispersant to the "sealing material composition". As the dispersant, various metal soaps can be used. Also, as the dispersant, in addition to metal soaps, low molecular weight polyethylene waxes and the like can also be used. Specific examples of preferable dispersants include lithium stearate, magnesium stearate, calcium stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, calcium ricinoleate, barium ricinoleate, zinc ricinoleate, zinc octylate, and the like. Among them, from the viewpoint of the melting point of the resin, calcium stearate, zinc stearate, zinc laurate, etc. are preferable. In particular, when calcium stearate, which is often contained in ordinary polyethylene-based resins, is applied as the dispersant, the compatibility does not deteriorate, and it can be preferably used.

[0083] Also, when the "sealing material sheet" of the present invention is made into a "black sealing material sheet", in order to promote good dispersion of the black pigment, a combination with an antioxidant is also important. It is preferable to add phenolic and phosphorus-based antioxidants to the resin component of the sealing material composition at a ratio of 200 ppm or more and 800 ppm or less.

[0084] (Light diffusing agent) When the "sealing material sheet" of the present invention is a "light-diffusing type sealing material sheet", the light diffusing agent used is not particularly limited as long as it can diffuse the light from the LED element, but preferably has a refractive index of 1.4 or more and 2.2 or less. Such a refractive index can be measured by the Becke method, the minimum deviation method, the deviation analysis, the mode-line method, the ellipsometry method, the Abbe method, or the like. Further, the refractive index of the light diffusing agent preferably has a predetermined refractive index difference from the base resin constituting the "sealing material sheet". Specifically, it is preferable that this refractive index difference is 0.03 or more, and more preferably 0.05 or more.

[0085] The light diffusing agent may be an organic material or an inorganic material. Specific examples of the light diffusing agent that is an organic material include synthetic resins such as polymethyl methacrylate (PMMA) resin particles, melamine resin particles, silicone resin particles, styrene resin, polyurethane resin, polyester resin, fluorine-based resin, or copolymers thereof. These may be used alone or in combination of two or more. On the other hand, specific examples of the light diffusing agent that is an inorganic material include TiO 2 、SiO 2 、Al 2 O 3 、silicon, zirconia, glass, smectite, kaolinite, and the like. Also for these, one kind may be used alone, or two or more kinds may be mixed and used.

[0086] In addition, from the viewpoint of dispersibility in the resin, the shape of the light diffusing agent is preferably particulate. And in this case, the average primary particle diameter (D50) of the light diffusing agent is preferably 0.1 μm or more and 50 μm or less, and more preferably 1 μm or more and 20 μm or less.

[0087] Further, the content of the light diffusing agent in the "sealing material composition" is preferably 0.1% by mass or more and 50% by mass or less. By setting the content of the light diffusing agent within the above range, the light emitted from the LED element can be surely diffused, and it is possible to avoid the light diffusing agent from being difficult to disperse and forming lumps. In addition, when the "sealing material sheet" has a multilayer structure, the content of the above light diffusing agent refers to the ratio of the light diffusing agent in the layer containing the light diffusing agent.

[0088] <Manufacturing method of the sealing material sheet> The "sealing material sheet" of the present invention can be manufactured by a method of melt-molding the "sealing material composition" described in detail above. The melt-molding of the sealing material composition can be performed by known molding methods, specifically, various molding methods such as injection molding, extrusion molding, blow molding, compression molding, and rotational molding. The lower limit of the molding temperature during molding may be a temperature exceeding the melting point of the sealing material composition. The upper limit of the molding temperature may be a temperature at which crosslinking does not start during film formation according to the 1-minute half-life temperature of the crosslinking agent used, that is, a temperature at which the gel fraction of the sealing material composition can be maintained at 10% or less, preferably 0%.

Examples

[0089] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

[0090] <Manufacture of the sealing material sheet for the self-luminous display> For each example and comparative example, each sealing material composition having each composition shown in Table 1 below was used for manufacturing. Linear low-density polyethylene resin (LLDPE) was used as the base resin, and "Luperox TBEC" (manufactured by Arkema Yoshitomi Co., Ltd.) was used as the crosslinking agent. The 1-hour half-life temperature of this crosslinking agent is 121°C. Film formation was carried out using a film forming machine having a φ30 mm extruder and a 200 mm wide T-die at an extrusion temperature of 90°C, a take-up speed of 1.1 m / min, and a film thickness of 450 μm in each case to manufacture the sealing material sheets of each example and comparative example.

[0091]

Table 1

[0092] <Evaluation Example 1: Heat Resistance> As a test for evaluating heat resistance, a "heat-resistant creep test" was conducted by the method described below. In the "heat-resistant creep test", first, a sealing material sheet of the example or comparative example cut into 5 cm × 7.5 cm was stacked on a glass plate, and a 5 cm × 7.5 cm glass plate was stacked on top of it. Using a vacuum laminator for manufacturing solar cell modules, a vacuum lamination treatment was performed under the conditions of a temperature of 150°C, a vacuum drawing time of 5 minutes, a press holding time of 10 minutes, and an upper chamber pressure of 50 KPa to prepare a "sample for heat resistance evaluation". After that, a large-sized glass was placed vertically and left at 100°C for 168 hours, and the moving distance (mm) of the 5 cm × 7.5 cm glass plate after leaving was measured, and the heat resistance of the "sealing material sheet" of the present invention was evaluated based on the following "evaluation criteria". The evaluation results are as shown in Table 2. (Evaluation Criteria) A: 0 mm or more and less than 0.5 mm B: 0.5 mm or more and less than 5 mm C: 5 mm or more

[0093] <Evaluation Example 2: Moldability> As a test for evaluating heat resistance, a "molding test" was conducted by the method described below. In the "molding test", first, an LED module was prepared in which LED elements with a minute size of width 25 μm × depth 15 μm × height 2.5 μm were arranged on the surface of a glass epoxy wiring board with a size of 200 × 300 mm at a 2 mm pitch. On the LED element arrangement surface of this module, a sealing material sheet of any one of each of the examples and each of the comparative examples with a thickness of 300 μm was laminated. Further, on the sealing material sheet, a 50 μm ethylene tetrafluoroethylene (ETFE) film subjected to one-sided corona treatment was laminated as a surface protection film. Using a vacuum laminator for manufacturing solar cell modules, vacuum lamination treatment was performed under the conditions of a temperature of 150°C, a vacuum drawing time of 5 minutes, a press holding time of 10 minutes, and an upper chamber pressure of 50 KPa to produce a "module for molding property test". After that, each of the above test modules was visually observed, and the molding property of the "sealing material sheet" of the present invention was evaluated based on the following "evaluation criteria". The evaluation results are as shown in Table 2. (Evaluation Criteria) A: The sealing material sheet completely followed the unevenness of the LED element arrangement surface facing it. No void formation was observed. B: Bubbles within 2 mm 2 were observed within 3. C: Bubbles within 2 mm 2 were observed exceeding 3, or a part of the sealing material sheet did not completely follow the unevenness of the LED element arrangement surface facing it, and a partially laminated defective part (void) was formed in the vicinity of the LED element.

[0094] <Gel fraction of the sealing material sheet> A 1.0 g test piece was sampled as a sample from each sealing material sheet constituting the above "sample for heat resistance evaluation", and the gel fraction of each sealing material sheet was measured by the "measurement method of gel fraction" described in detail above. The measurement results are as shown in Table 2.

[0095] <Melting point and extrapolated onset melting temperature of the sealing material sheet> The melting point and the supplementary melting start temperature of each sealing material sheet in the uncrosslinked state after film formation were measured by the measurement method described in detail above (the measurement method based on "Differential Scanning Calorimetry (DSC), JIS K 7121-1987"). The measurement results are as shown in Table 2.

[0096]

Table 2

[0097] From Table 2, it can be seen that the "sealing material sheet" of the present invention is a "sealing material sheet" having sufficient moldability with respect to a fine uneven surface and having a high heat resistance that can withstand use even in a particularly high temperature environment.

Explanation of Signs

[0098] 1 Sealing material sheet 2 Display surface panel 3 Diffusion plate 10 LED elements 11 LED light-emitting chips 12 Resin cover 13 Light diffusion type lens 20 Wiring board 21 Support substrate 22 Wiring part 23 Solder layer 24 Adhesive layer 25 Insulating protective film 26 Reflective layer 30 LED module 100, 100A, 100B Micro LED display device (self-luminous display body) 200 Direct-lit backlight 300 Liquid crystal display body (direct-lit backlight method)

Claims

1. An encapsulant sheet for a self-luminous display or a direct backlight, The base resin is an olefin resin. The melting point is 45°C or more and 60°C or less, The resin component contains a crosslinking agent in an amount of 0.1% by mass or more and 1.2% by mass or less, The gel fraction after the crosslinking treatment is 50% or more and 90% or less. Encapsulating sheet.

2. The density of the base resin is 0.875 g / cm ３ 0.900g / cm or more ３ Below is the The encapsulating material sheet according to claim 1 .

3. The thickness is 3 μm or more and 1000 μm or less. The sealing material sheet according to claim 1 or 2.

4. The gel fraction after crosslinking treatment under the following heating conditions is 50% or more and 90% or less. The sealing material sheet according to claim 1 or 2. (Heating conditions) A sheet of the sealing material is placed on a glass plate, and a glass plate is placed on top of the sheet, followed by vacuum lamination under conditions of a temperature of 150° C., a vacuuming time of 5 minutes, a press holding time of 10 minutes, and a pressure of 50 KPa.

5. The sealing material sheet according to claim 1 or 2, A display panel; a light emitting module in which a plurality of light emitting elements are mounted on a wiring board; the sealing material sheet covers the light-emitting element and the wiring board and is laminated on the light-emitting module, The display panel is laminated on the sealing material sheet. Self-luminous display.

6. The light emitting element is an LED element, The width and depth of the LED element are both greater than 50 μm and less than 300 μm, and the height is less than 200 μm, The arrangement interval between each of the LED elements is 0.03 mm or more and 100 mm or less.

6. The self-luminous display according to claim 5.

7. The light emitting element is an LED element, The width and depth of the LED element are both 50 μm or less, and the height is 10 μm or less, The arrangement interval between each of the LED elements is 0.005 mm or more and 5 mm or less.

6. The self-luminous display according to claim 5.

8. The sealing material sheet according to claim 1 or 2, a light emitting module in which a plurality of light emitting elements are mounted on a wiring board; the sealing material sheet covers the light-emitting element and the wiring board and is laminated on the light-emitting module; Direct type backlight.

9. A direct type backlight according to claim 8; A diffusion plate; A display surface panel, The diffusion plate is laminated on the sealing material sheet constituting the direct type backlight. liquid crystal display.

Images