JP2022103204A - Self-luminous display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a layer structure of a self-luminous display including a light shielding layer as compared with a conventional self-luminous display.

SOLUTION: In a self-luminous display 100, a plurality of light-emitting elements 10 includes a light emitting module 30 mounted on a wiring substrate 20, a black encapsulant sheet 1 which is a resin sheet containing a black pigment by using an olefin resin as a base resin, and a transparent optical layer 2, and the black encapsulant sheet 1 covers the top and side surfaces of the light emitting element 10 and the surface of the wiring substrate 20 and is laminated on the light emitting module 30, and a transparent optical layer 2 is laminated on the black encapsulant sheet 1.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a self-luminous display body. More specifically, the present invention relates to a self-luminous display body represented by a micro LED television, which has a simpler layer structure than a conventional self-luminous display body due to its own design concept.

As a next-generation display device that replaces various liquid crystal display devices, a self-luminous display body represented by a micro LED television is being developed (see Patent Document 1).

In this self-luminous display body, a transparent encapsulant sheet for protecting the light emitting element is provided on the surface of the LED module on the light emitting surface side, which is configured by mounting a light emitting element such as an LED element on a wiring substrate. They are laminated (see Patent Document 2).

In many self-luminous displays, a light-shielding layer made of a black resin film or the like containing a material that absorbs visible light is further laminated on the transparent encapsulant sheet (see Patent Document 3). ). This light-shielding layer is arranged in order to prevent the light reflected on the substrate or the like on which the light-emitting element as a light source is mounted in the self-luminous display body from adversely affecting the displayed image quality. ..

Japanese Unexamined Patent Publication No. 2018-14481 Japanese Unexamined Patent Publication No. 2014-148584 JP-A-2015-197543

An object of the present invention is to simplify the layer structure of a self-luminous display body including a light-shielding layer as described above, as compared with a conventional self-luminous display body.

Based on our unique design concept, the present inventors have applied a black encapsulation material to a transparent encapsulant placed on a substrate on which a light emitting element as a light source is mounted even in a conventional self-luminous display body. By using the material, the layer structure of the self-luminous display body including the light-shielding layer can be simplified as compared with the conventional case, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A light emitting module in which a plurality of light emitting elements are mounted on a wiring substrate, a black encapsulant sheet using an olefin resin as a base resin and a visible light transmittance of 5% or more and 70% or less, and a transparent optical layer. The black encapsulant sheet covers the surface of the light emitting element and the wiring substrate and is laminated on the light emitting module, and the transparent optical layer is laminated on the black encapsulant sheet. A self-luminous display.

According to the invention of (1), the layer structure of the self-luminous display body including the light-shielding layer can be simplified as compared with the conventional self-luminous display body. This makes it possible to improve the productivity of the self-luminous display body represented by the micro LED television.

(2) The black pigment contained in the black encapsulant sheet is carbon black, and the content of the carbon black in the resin component of the black encapsulant sheet is 0.0001% by mass or more. The self-luminous display according to (1), which is 08% by mass or less.

In the invention of (2), when the content of carbon black in the resin component of the black encapsulant sheet is 0.0001% by mass or more, stable coloring with sufficiently few spots is possible. On the other hand, when the content is 0.08% by mass or less, it is possible to transmit the light of the LED with an appropriate transmittance.

(3) The black encapsulant sheet contains a dispersant composed of one or more kinds of metal soaps, and the content of the dispersant in the resin component of the black encapsulant sheet is 0. The self-luminous display according to (1) or (2), which is 0001% by mass or more and 0.002% by mass or less.

In the invention of (3), when forming a transparent black sheet having a visible light transmittance of 5% or more, it is essential to enhance the dispersibility of the pigment in particular, but within the above range, By adding the dispersant, the dispersibility of the pigment can be sufficiently enhanced while preventing the screw from slipping during film formation.

(4) The support substrate of the wiring board is a glass epoxy-based hard substrate, and the surface color of the support substrate on the LED element mounting surface side is colored other than white and black (1) to (3). The self-luminous display body described in any of the above.

In the invention of (4), in a self-luminous display body such as a micro LED display device that uses a colored glass epoxy-based substrate typified by brown as the support substrate, the support substrate arranged inside is, for example, brown. It is possible to effectively reduce the deterioration of the display quality due to the reflected light from the substrate, which tends to be a problem especially when the surface is a colored surface such as a system.

(5) The self-luminous display body according to any one of (1) to (4), wherein the light emitting element is an LED element.

The invention (5) is an application of the present invention to various self-luminous LED display devices represented by micro LED televisions, which are expected to be the mainstream of next-generation monitors. As a result, it is possible to obtain a self-luminous LED display device having higher productivity than the conventional product.

(6) The LED element has an LED light emitting chip and a resin cover covering the LED light emitting chip, and the width and depth of the LED element are both 300 μm or less and the height is 200 μm or less. The self-luminous display according to (5), wherein the arrangement interval of each of the LED elements is 0.03 mm or more and 100 mm or less.

In the invention of (6), the self-luminous display body of (5) is provided in a high-definition dot matrix display device or the like in which LED elements are densely mounted by a chip-on-board method in which a large number of LED chips are directly mounted on a substrate. It is an application. This makes it possible to obtain a high-definition LED display device having excellent productivity.

(7) The width and depth of the LED elements are both 50 μm or less, the height is 10 μm or less, and the arrangement interval of each of the LED elements is 0.05 mm or more and 5 mm or less (6). ) The self-luminous display body.

The invention of (7) is an application of the self-luminous display body of (5) to a "micro LED television" which is being developed in recent years and is expected as a next-generation video display device. As a result, it is possible to obtain an ultra-high-definition LED display device having excellent productivity.

According to the present invention, the layer structure of the self-luminous display body including the light-shielding layer can be simplified as compared with the conventional self-luminous display body, and various self-luminous types such as micro LED televisions can be simplified. It can contribute to the improvement of the productivity of the display body.

It is a plan view of the image display surface for the self-luminous display body of this invention, and is a partially enlarged plan view thereof. It is a figure showing the cross section of the part AA of FIG. 1, and is the figure which shows typically the layer structure of the self-luminous display body of this invention. It is a figure which shows typically the layer structure of the black encapsulant sheet which concerns on this invention which constitutes the self-luminous display body of FIG. It is a perspective view of the LED element constituting the LED module for the self-luminous display body of FIG. It is a figure which shows typically the layer structure of the conventional self-luminous display body.

<Self-luminous display>
First, the "self-luminous display body" in the present specification is a display device typified by the micro LED television exemplified above, and is a display device for visual information such as characters, images, and moving images. In this display device, a small number of light emitting elements are mounted in a matrix on a wiring board, and each light emitting element is selectively emitted by a light emitting control means connected to the light emitting element, whereby the above visual information is obtained. It is a display device that can be displayed directly on the display screen by blinking the light emitting element.

The "self-luminous display body" of the present invention can be preferably implemented as an LED display device using an LED element as a light emitting element. Further, the LED element in this case is more preferably a "small size LED element". In the present specification, the "small size LED element" specifically refers to the width (W) and the depth (D) with respect to the size of the entire light emitting element including the LED light emitting chip and the resin cover covering the LED light emitting chip. ) Shall be an LED element having a height (H) of 200 μm or less and 300 μm or less (see FIG. 4).

Further, regarding the size of this "small size LED element", it is more preferable that the width and the depth are both 50 μm or less and the height is 10 μm or less. This size range is a standard size range for LED elements mounted on micro LED televisions, which have been developed in recent years and are expected to become the mainstream of next-generation televisions. Hereinafter, in the present specification, a micro-sized LED element having a width and a depth of 50 μm or less and a height of 10 μm or less has a pitch of several μm to several tens of μm, and is several thousand × several thousand. A self-luminous display body arranged in a matrix with a number of more than a certain number is referred to as a "micro LED display device".

In the following, the present invention takes up an embodiment in which the "self-luminous display body" is a "micro LED display device" as a particularly preferable and specific example among various embodiments of the present invention. I will give a detailed explanation of. However, the technical scope of the present invention is not limited to the application only to the "micro LED display device". It is a technique that can be applied to all "self-luminous displays" as defined above.

[Micro LED display device]
FIG. 1 is a front view of the micro LED display device 100, which is an embodiment of the self-luminous display body of the present invention, and a partially enlarged view (100A) thereof. Further, FIG. 2 is a cross-sectional view showing a cross section of the portion AA of FIG. 1, and is a drawing used for explaining the layer structure of the micro LED display device 100 (100B) shown in FIG. The micro LED display device 100 (100B) is a "light emitting module" for a self-luminous display body in which a large number of minute-sized "LED elements 10" are mounted on a wiring board 20 as "light emitting elements". It is a self-luminous display device including 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 bonded separately.

In the micro LED display device 100 (100B), as shown in FIG. 2, the mounting surface of the LED element 10 of the LED module 30 is covered with the LED element 10, and the visible light transmittance is 5% or more and 70% or less. The black sealing material sheet 1 which is a resin sheet is laminated. Further, the black encapsulant sheet 1 is laminated on the LED module (light emitting module) 30 in close contact with the top surface and all side surfaces of the LED element (light emitting element) 10 and the surface of the wiring board 20. Is preferable. The black encapsulant sheet 1 is also in close contact with the side surface of the LED element 10 due to its excellent molding property, so that light is emitted from the side surface, particularly when the LED element is of a type that also emits light from the side surface. It is possible to prevent the display from losing the color balance and having poor color reproducibility due to the light being applied to the glass epoxy-based substrate and the color of the substrate being reflected and leaking from the display surface. Further, in the light emitting module disclosed in Patent Document 3, a through hole is formed in the light shielding layer directly above the LED element, but in a self-luminous display body such as a micro LED TV, it is higher than that of a liquid crystal TV. It is possible to emit light of brightness, and it is possible to apply a light-shielding layer having no opening in order to improve color reproducibility. Details of the composition, layer structure, etc. of the black encapsulant sheet 1 will be described later.

Further, in the micro LED display device 100 (100B), as also shown in FIG. 2, the transparent optical layer 2 made of various optical films and the like is further attached to the outer surface side (micro LED display device 100) of the black encapsulant sheet 1. It is laminated on the display surface side).

Here, as disclosed in Patent Document 3 and the like, in the conventional micro LED display device 100C, as shown in FIG. 5, a transparent sealing material 1C is provided on the surface of the LED module (light emitting module) 30. It was laminated, and the light-shielding layer 4 was separately arranged on the surface thereof via the adhesive layer 3A. The same transparent optical layer 2 as described above is further laminated on the surface of the light-shielding layer 4 via the adhesive layer 3B.

On the other hand, in the micro LED display device 100 (100B) (see FIG. 2) of the present invention, the LED element protection function of the sealing material 1C in the conventional micro LED display device 100C shown in FIG. 5 and the light shielding layer 4 are provided. The optical function of the above is provided only to the black encapsulant sheet 1, which simplifies the layer structure of the entire display device while maintaining each function of the conventional product.

In the present invention, a plurality of LED modules 30 for self-luminous display bodies are joined in a matrix on the same plane, and the black encapsulant sheet 1 is attached to the joined LED modules in the same manner as described above. By stacking, it is possible to configure an LED module for a large self-luminous display body, and further, a large micro LED display device. In this case, the excellent film thickness uniformity of the black encapsulant sheet 1 after hot press processing maintains the uniformity of the display surface at the joint between the individual LED modules to be bonded, and such a large size. It can also contribute to the improvement of the image quality of the micro LED display device.

(Manufacturing method of micro LED display device)
The micro LED display device 100 (100B) is a laminate obtained by laminating an LED module 30 for a self-luminous display body in which an LED element 10 is mounted on a wiring board 20, a black encapsulant sheet 1, and a transparent optical layer 2. It can be manufactured by forming a body and integrating the laminated body by hot pressing. If necessary, it is preferable to join some of the laminated members with an adhesive in advance before the above-mentioned hot press working. For example, for the transparent optical layer 2, it is preferable to manufacture the micro LED display device 100 by a procedure of adhering it to the black encapsulant sheet 1 via the adhesive layer 3.

(LED module for self-luminous display)
As shown in FIG. 2, the LED module 30 which is a light emitting module for a self-luminous display of the present invention is configured by mounting an LED element 10 on a wiring board 20 in which a wiring portion 22 is formed on a support board 21. Ru.

As shown in FIG. 2, in the wiring board 20, a wiring portion 22 formed of, for example, a metal such as copper or another conductive member is formed on the surface of the support substrate 21 so as to be conductive with the LED element 10. It is a circuit board made of As the support substrate 21, a conventionally known glass epoxy-based hard substrate can be used as the substrate for the electronic circuit.

Here, the glass epoxy-based hard substrate usually has a brownish tint on its surface. Conventionally, in a micro LED display device, the light reflected on the surface of the support substrate arranged inside having a brownish tint is transmitted to the outside on the display surface side, so that the display quality is improved. May cause a decline. In order to prevent such a problem, in the micro LED display device 100C (see FIG. 5) having a conventional configuration, the light-shielding layer 4 as shown in the figure is on a transparent sealing material sheet 1D that transmits almost all visible light. It was laminated separately in. On the other hand, in the micro LED display device 100 (100B) (see FIG. 2) of the present invention, the transmittance of visible light is 5% or more and 70% as a sealing material having the function of the light-shielding layer 4 in the conventional configuration. The following black encapsulant sheet 1 is arranged. Therefore, the present invention exhibits a particularly advantageous effect in a micro LED display device using a glass epoxy-based hard substrate having a colored surface other than white and black as the support substrate 21 as a representative of brown-based colors.

In the LED module 30, as shown in FIG. 2, the LED element 10 is mounted on the wiring portion 22 via the solder layer 23 in a conductive manner.

The size of the LED module 30 is not particularly limited, but a module having a diagonal length of about 50 inches to 200 inches is generally preferable from the viewpoint of cost performance. Further, as described above, a plurality of LED modules 30 for self-luminous display bodies are joined in a matrix on the same plane to form a light emitting surface of a self-luminous display body such as a large micro LED display device. be able to. For example, a micro LED television having a large screen having a diagonal length of 600 inches can be configured by joining 100 × 100 LED modules 30 having a diagonal length of 6 inches vertically and horizontally.

(LED element)
The LED element 10 mounted on the wiring board 20 and constituting the LED module 30 for the self-luminous display is a light emitting element utilizing light emission at the PN junction where the P-type semiconductor and the N-type semiconductor are joined. A structure in which P-type electrodes and N-type electrodes are provided on the upper and lower surfaces of the device and a structure in which both P-type and N-type electrodes are provided on one surface of the device have been proposed. The LED element 10 having any structure can be used in the LED display device 100 (100B) of the present invention, such as the LED element disclosed as a "chip-shaped electronic component" in Japanese Patent Application Laid-Open No. 2006-339551. A micro size LED element can be particularly preferably used. The LED element disclosed in the same document is said to have a size of width × depth × height of approximately 25 μm × 15 μm × 2.5 μm.

The LED element 10 preferably includes an LED light emitting chip 11 and a resin cover 12 that covers the LED element 10. Further, as the resin cover 12, an organic insulating material such as an epoxy resin, a silicon resin, or a polyimide resin is used, and among these, an epoxy resin is particularly preferably used. The resin cover 12 formed of the epoxy resin not only protects the LED light emitting chip 11 from physical impact, but also enters the semiconductor due to the difference in refractive index between the semiconductor constituting the LED light emitting chip 11 and air. This is because it also plays a role of suppressing total reflection of light and increasing the light emission efficiency of the LED element 10. The black encapsulant sheet 1 is preferable as an encapsulant to be mounted on the micro LED display device 100 (100B) in that it is formed of an olefin resin having excellent adhesion to an epoxy resin.

The self-luminous display body of the present invention is an LED element including an LED light emitting chip and a resin cover covering the LED light emitting chip, and has a width and a depth of 300 μm or less and a height of 200 μm or less. A size LED element can be preferably used. In this case, the arrangement interval of the LED elements is preferably 0.03 mm or more and 100 mm or less.

Further, the self-luminous display body of the present invention is an LED element including an LED light emitting chip and a resin cover covering the LED light emitting chip, and the width and depth are both 50 μm or less and the height is high. An extremely fine size LED element having a size of 10 μm or less can be more preferably used. In this case, the arrangement interval of the LED elements is preferably 0.03 mm or more and 100 mm or less. Specifically, such a mounting mode of the LED element is also a standard mounting mode of the LED element in the micro LED television.

(Black encapsulant sheet)
In the micro LED display device 100 (100B) according to the present invention, the black encapsulant sheet 1 laminated on the LED module 30 is formed with an encapsulant composition using an olefin resin such as polyethylene as a base resin. , It is a sheet-like member having a "black" color.

Here, "black" in the present specification means that the CIE color coordinates measured according to JISZ8701-1999 with a C light source and a viewing angle of 2 deg are -1.0 ≤ a ^* ≤ 2.5 and -1. It is in the range of 0.0 ≦ b ^* ≦ 15.0, and the L ^* value refers to the color in the range of 0 ≦ L ^* ≦ 50.

The black encapsulant sheet 1 may be a single-layer film, but as shown in FIG. 3, a multilayer composed of a core layer 1A and skin layers 1B and 1C arranged on both sides of the core layer 1A. It is preferably a film. The multilayer film in the present specification refers to a film or sheet having a structure having at least one outermost layer, preferably a skin layer formed into both outermost layers, and a core layer which is a layer other than the skin layer. To tell. When the black encapsulant sheet 1 has a three-layer structure consisting of a skin layer, a core layer, and a skin layer, a black pigment is added only to the core layer 1A, and this is applied to the skin layers 1B and 1C exposed on both outermost surfaces. It is more preferable to leave the transparent layer as it is without adding. This makes it possible to prevent the rubber roll, embossing roll, cooling roll, guide roll, and the like of the film forming apparatus from being contaminated with the black pigment.

The thickness of the black encapsulant sheet 1 may be 50 μm or more and 1000 μm or less, preferably 50 μm or more and 500 μm or less, and more preferably 50 μm or more and 300 μm or less. When the LED element to be covered is an LED element having an extremely small size having a height of 10 μm or less, the thickness of the encapsulant sheet is preferably 25 μm or more and 100 μm or less. When the thickness of the encapsulant sheet is 50 μm or more, the LED element can be sufficiently protected from an external impact. On the other hand, when the thickness of the encapsulant sheet is 1000 μm or less, sufficient molding property can be exhibited. Specifically, during hot press working with the LED element covered, the resin constituting the encapsulant sheet can sufficiently wrap around the unevenness of the surface of the LED module to perform good laminating without gaps. can.

The black colorant used to impart an appropriate color to the black encapsulant sheet 1 is preferably a pigment-based material. For example, carbon black, which is generally used as a black pigment, can be mentioned as an example of a preferable pigment. When coloring for display applications, black color is often developed by combining a plurality of dyes, but in that case, if the pressure becomes non-uniform during adhesive bonding, color unevenness is likely to occur. In addition, as a durability test of the display, a durability test in an environment of 85 ° C. 85% or 60 ° C. 90% is required, but in the case of a pigment system, pigment deterioration (fading deterioration) is likely to occur, and a pigment system should be used. Is preferable. However, if it is necessary to reduce the transmittance of a specific wavelength in order to widen the color tone region, it is also possible to apply a dye.

When carbon black is used as the black pigment used in the black encapsulant sheet 1, the content of carbon black in the resin component of the black encapsulant sheet may be 0.0001% by mass or more and 0.08% by mass or less. preferable. In order to develop the blackness required when the carbon black content is less than 0.0001% by mass, the thickness of the encapsulant sheet should be larger than necessary for maintaining the original encapsulation function. It will be necessary to do. Further, when the content exceeds 0.08% by mass, the light of the LED cannot be appropriately transmitted, and it becomes difficult to obtain a preferable image. By setting the content of carbon black within the above range, stable coloring with sufficiently few spots is possible.

Further, it is more preferable to add a dispersant to the black encapsulant sheet 1. As the dispersant, various metal soaps can be used. Further, as the dispersant, it is also possible to use a low amount of polyethylene wax or the like in addition to the metal soap. Specific examples of preferred dispersants include lithium stearate, magnesium stearate, calcium stearate, zinc stearate barium stearate, calcium laurate, barium laurate, zinc laurate, calcium lysinolate, barium ricinolate, zinc lysinolate, and the like. Examples thereof include zinc octylate. Among them, calcium stearate, zinc stearate, zinc laurate and the like are preferable from the viewpoint of the melting point of the resin, and in particular, when calcium stearate, which is often contained in ordinary polyethylene-based resins, is applied to the dispersant, the compatibility may deteriorate. However, it can be preferably used.

Here, when forming a film having a concealing property, it is usually not necessary to consider streaks such as die lines at the time of film formation, but the visible light transmittance is 5% like the black encapsulant sheet 1. When forming the above-mentioned transparent sheet, it is essential to improve the dispersibility of the pigment. If the amount added is small, the effect of dispersion is diminished, and if the amount added is large, it causes slippage during film formation. Therefore, the content of the above-mentioned dispersant in the resin component of the encapsulant composition is 0.00002. It is preferably mass% or more and 0.002 mass% or less. When the content of the dispersant is less than 0.00002% by mass, the coloring concentration varies due to the decrease in the dispersibility of the pigment, and for example, a striped pattern is formed on the surface, which is used as a self-luminous display. Increases the risk of being in an inappropriate state, and if the content exceeds 0.002% by mass, it is possible to maintain a constant film thickness due to the slippage of the screw during film formation. The risk of difficulty increases. On the other hand, by adding the dispersant within the above range, the dispersibility of the pigment can be sufficiently enhanced while preventing the screw from slipping during film formation.

Further, in the black encapsulant sheet 1, in order to promote good dispersion of the pigment, it is important to combine it with an antioxidant, and a phenolic or phosphorus-based antioxidant is used in the encapsulant composition. It is preferable to add it to the resin component at a ratio of about 200 to 800 ppm.

In the self-luminous display body of the present invention, the "melt viscosity (η * 1) at a shear rate of 2.43 × 10sec ^-1 measured at a temperature of 120 ° C." of the black encapsulant sheet 1 is 1. It is preferably 0.0 × 10 ³ poise or more and 1.0 × 10 ⁵ poise or less, and more preferably the melt viscosity is 5.0 × 10 ³ poise or more and 1.0 × 10 ⁵ poise or less. The above-mentioned melt viscosity in the present specification refers to the melt viscosity measured by a method according to JIS K7199.

By setting the above "melt viscosity" to 1.0 x 10 ³ poise or more, it is caused by resin squeeze out due to excessive flow during hot press working of the encapsulant sheet and lateral stress on the LED element. It is possible to sufficiently suppress the occurrence of light emission defects, and it is also possible to maintain good uniformity of the film thickness of the encapsulant sheet after the hot press working. In a self-luminous display body such as the micro LED display device 100, the sealing material sheet laminated on the light emitting surface side of the LED element is required to have a particularly uniform film thickness. This is because if the film thickness at the center and the film thickness at the edges of the black encapsulant sheet 1 are slightly different, the encapsulant sheet becomes in a lens-like state, which is intended for the display quality of the micro LED display device. This is because it has an unfavorable effect.

^On the other hand, by setting the above-mentioned "melt viscosity" to 1.0 × 105 poise or less, the molding property of the encapsulant sheet at the time of hot press working can be well maintained.

Here, the value of MFR, which has been widely adopted as a guideline for the fluidity of the encapsulant sheet, is measured at 190 ° C. when measured in accordance with JIS K6922, but this temperature is actually measured. The temperature at which the encapsulant sheet for the self-luminous display is melted during hot pressing is different from the temperature. As will be shown later in Examples, even if the value of MFR is in the range of an appropriate value, if the above-mentioned "melt viscosity" exceeds a predetermined value, the required molding property may not be ensured. As an index for controlling the fluidity of the resin during hot pressing, instead of MFR, as described above, the shear modulus at a temperature of 120 ° C., that is, the shear rate measured at a temperature of 120 ° C. 2. By using the melt viscosity (η * 1) at 43 × 10 sec-1 as an index for optimizing the physical properties of the base resin, a more effective and precise resin that is more in line with the actual usage of the encapsulant sheet. You can get an index related to selection.

Further, in the self-luminous display body of the present invention, the vicut softening point of the black encapsulant sheet 1 is preferably more than 60 ° C. and 100 ° C. or lower, and more preferably 70 ° C. or higher and 90 ° C. or lower. preferable. By setting the vicut softening point of the black encapsulant sheet 1 to exceed 60 ° C., the occurrence of blocking in the manufacturing process of the self-luminous display body using the encapsulant sheet is more reliably suppressed, and the self-luminous display is performed. It can contribute to the improvement of body productivity. On the other hand, by setting this temperature range to 100 ° C. or lower, it is possible to sufficiently maintain the molding property required for the encapsulant sheet for the self-luminous display body.

Further, it is preferable to optimize the vicut softening point of the encapsulant sheet more strictly according to the melting point of the encapsulant sheet. Specifically, when the melting point of the encapsulant sheet is in a relatively low range of 50 ° C to less than 70 ° C, the Vicat softening point is set to 60 to 70 ° C in order to suppress excessive flow during hot press working. It is preferably in the range of less than. When the melting point is in a relatively high range of 70 ° C. or higher, the Vicat softening point is preferably in the range of 70 ° C. to 100 ° C. in order to maintain good molding properties during hot press working. The "vicut softening point" of the sealing material sheet in the present specification is a sealing material obtained by forming a sealing material composition containing a resin component and other additives into a sheet by a molding method such as extrusion melt molding. It is assumed that the bicut softening point at the stage after the sheet formation is completed is a value measured based on ASTM D1525.

From another point of view, in the self-luminous display body of the present invention, the durometer A hardness of the black encapsulant sheet 1 is preferably 60 or more and less than 95. If the durometer A hardness of the encapsulant sheet is less than 60, the crystallization rate of the olefin resin becomes slow and the sheet extruded from the extruder becomes sticky, which makes it difficult to peel off with a cooling roll and seals. It becomes difficult to obtain a material sheet. In addition, the encapsulant sheet becomes sticky, which causes blocking and makes it difficult to feed the sheet. On the other hand, when the hardness of the durometer A exceeds 95, the molding property is lowered and the followability to the unevenness of the LED element becomes insufficient.

In the self-luminous display body of the present invention, the melt mass flow rate (MFR) of the resin sheet constituting the black encapsulant sheet 1 at 190 ° C. is 0.1 g / 10 min or more and less than 12.0 g / 10 min. It is preferable, and it is more preferable that it is 0.1 g / 10 min or more and less than 5.0 g / 10 min.

In the present specification, "MFR" of the encapsulant sheet is a encapsulant sheet obtained by forming a encapsulant composition containing a resin component and other additives into a sheet by a molding method such as extrusion melt molding. The MFR at the stage after the completion of sheeting shall be the value measured under the condition of 190 ° C. and 2.16 kg load in accordance with JIS K7210. Regarding the MFR when the encapsulant sheet is a multilayer film, the measurement is performed by the above treatment while all the layers are integrally laminated, and the obtained measured value is used for the multilayer encapsulant sheet. It shall be the MFR value.

As the base resin of the encapsulant composition forming the black encapsulant sheet 1, an olefin-based thermoplastic resin can be widely selected. Among them, polyethylene-based resins such as low-density polyethylene-based resin (LDPE), linear low-density polyethylene-based resin (LLDPE), and metallocene-based linear low-density polyethylene-based resin (M-LLDPE) can be preferably used. In the present specification, the "base resin" refers to a resin having the largest content ratio among the resin components of the resin composition in the resin composition containing the base resin.

As the olefin resin used as the base resin of the encapsulant composition forming the black encapsulant sheet 1, a polyethylene resin having a density of 0.870 g / cm ³ or more and 0.910 g / cm ³ or less is preferably used. Can be done. By setting the density of the base resin of the encapsulant composition to 0.910 g / cm ³ or less, the adhesion of the encapsulant sheet to the wiring board or the like can be maintained within a preferable range. Further, by setting the same density to 0.890 g / cm ³ or more, the sealing material sheet can be provided with necessary and sufficient heat resistance without undergoing a crosslinking treatment.

The encapsulant composition contains a silane copolymer (hereinafter, also referred to as “silane-modified polyethylene-based resin”) obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer, if necessary. , It is more preferable to contain a certain amount in each encapsulant composition. The silane-modified polyethylene-based resin is obtained by graft-polymerizing a linear low-density polyethylene-based resin (LLDPE) or the like as a main chain with an ethylenically unsaturated silane compound as a side chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to adhesive strength, the black encapsulant sheet 1 is adhered to other members in a self-luminous display body such as a micro LED display device 100. It is possible to improve the sex. The content of this silane-modified polyethylene-based resin in the encapsulant composition is, for example, in the case of a multi-layer encapsulant sheet having a structure of a skin layer-core layer-skin layer, encapsulation for the core layer. It is preferably 2% by mass or more and 20% by mass or less in the material composition, and 5% by mass or more and 40% by mass or less in the sealing material composition for the skin layer. In particular, it is more preferable that the encapsulant composition for the skin layer contains 10% or more of silane-modified polyethylene. The amount of silane modification in the above-mentioned silane-modified polyethylene-based resin is preferably about 1.0% by mass or more and 3.0% by mass or less. The preferred content range of the silane-modified polyethylene-based resin in the encapsulant composition is based on the premise that the silane-modified amount is within this range, and is appropriately fine-tuned according to the fluctuation of the modified amount. Is desirable.

By using a silane-modified polyethylene-based resin as a component of a sealing material composition for a self-luminous display body, it has excellent strength, durability, etc., and also has weather resistance, heat resistance, water resistance, light resistance, and wind pressure resistance. It has excellent haze resistance and other properties, and has extremely excellent heat fusion properties without being affected by manufacturing conditions such as heat pressure bonding for manufacturing self-luminous displays, and is stable and low. At a low cost, it is possible to manufacture a self-luminous display body suitable for various uses.

The black encapsulant sheet 1 is preferably a thermoplastic encapsulant that does not require a cross-linking treatment after film formation. As such a "crosslinking-free" encapsulant sheet, a "weakly crosslinked encapsulant" obtained by weakly crosslinking a polyethylene-based encapsulant composition can also be used. "Weakly cross-linked" is a cross-linking processing technique according to the method for producing a sealing material disclosed in International Publication No. 2011/152314 in detail, and is a very weak cross-linking while maintaining a gel fraction of 0%. This is a technique for forming a film of a sealing material composition while advancing. In the present specification, the weakly crosslinked sealing material formed through this weakly crosslinking treatment is referred to as a "weakly crosslinked sealing material". The weakly crosslinked encapsulant has been weakly crosslinked at the time of film formation, and the crosslinking agent does not substantially remain after the film formation. Therefore, no separate cross-linking treatment is required in the manufacturing process of the self-luminous display.

This weakly cross-linked encapsulant uses a polyethylene resin with a density of 0.870 g / cm ³ or more and 0.890 g / cm ³ or less as a base resin, and is a seal for a light-receiving surface side encapsulant containing a very small amount of a cross-linking agent. It can be obtained by subjecting the above-mentioned weak cross-linking treatment during the film formation in the process of film-forming the stop material composition by a conventionally known method.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Manufacturing of encapsulant sheet for self-luminous display>
The following encapsulant composition was used as a first layer (skin layer): φ30 mm extruder, a second layer (core layer): φ30 mm extruder, and a third layer (skin layer): φ30 mm extruder, with a layer ratio of 1: With a 3: 1 configuration, the molten resin of the three layers of skin layer-core layer-skin layer is extruded at 210 ° C. and a take-up speed of 1.1 m / min using a film forming machine having a T-die having a width of 300 mm. , A sheet was formed with a film thickness of 150 μm, and a sealing material sheet of each Example and Comparative Example was produced. Regarding the cooling roll directly under the T-die and the rubber roll, a chrome-plated cooling roll having a surface roughness Rz of 1.5 μm was used as the cooling roll, and a silicone rubber roll having a hardness of 70 degrees was used as the rubber roll.
As the encapsulant composition for the first layer (skin layer), 100 parts by mass of the following "base resin 1", 5 parts by mass of the following "additional resin 1 (weather resistant masterbatch)", and ""Additional resin 2 (silane-modified polyethylene resin)" was mixed at a ratio of 20 parts by mass.
As the encapsulant composition for the second layer (core layer), 100 parts by mass of the following "base resin 1", 5 parts by mass of the following "additional resin 1 (weather resistant masterbatch)", and " 1 part by mass of "additive resin 2 (silane-modified polyethylene resin)" and 0.1 part by mass of "additive resin 3 (black masterbatch)" were mixed.
As the encapsulant composition for the third layer (skin layer), 100 parts by mass of the following "base resin 1", 5 parts by mass of the following "additional resin 1 (weather resistant masterbatch)", and ""Additional resin 2 (silane-modified polyethylene resin)" was mixed at a ratio of 20 parts by mass.
Base resin 1
: Metallocene-based linear low-density polyethylene-based resin (M-LLDPE) having a density of 0.901 g / cm ³ , a melting point of 93 ° C., and an MFR of 2.0 g / 10 minutes at 190 ° C.
Additive resin 1 (weather resistant masterbatch)
: KEMISTAB62 (HALS): 0.6 parts by mass with respect to 100 parts by mass of a low-density polyethylene resin having a density of 0.919 g / cm ³ and an MFR of 3.5 g / 10 minutes at 190 ° C. KEMISORB12 (UV absorber): 3.5 parts by mass. KEMISORB79 (UV absorber): 0.6 parts by mass.
Additive resin 2 (silane-modified polyethylene resin)
: To 100 parts by mass of a metallocene-based linear low-density polyethylene-based resin having a density of 0.900 g / cm ³ and an MFR of 2.0 g / 10 minutes, 2 parts by mass of vinyltrimethoxysilane and a radical generator (reaction). A silane-modified polyethylene-based resin obtained by mixing 0.15 parts by mass of a radical peroxide as a catalyst), melting at 200 ° C., and kneading. The density of the added resin 2 is 0.901 g / cm ³ , and the MFR is 1.0 g / 10 minutes.
Additive resin 3: (black masterbatch)
Linear low density polyethylene (LLDPE) with a density of 0.91 g / cm3 and an MFR of 5.0 g / 10 min, 40 parts by mass of carbon black, 2 parts by mass of metal soap (calcium stearate), and a density of 0.910 g / cm3. ) Black master batch with 60 parts by mass.

<Evaluation example 1: Film thickness uniformity>
An untreated ETFE of 50 μm was laminated as a release film on the front and back of the encapsulant sheet of the example cut into 30 × 30 cm, and then glass having a thickness of 30 × 30 cm and a thickness of 3 mm was laminated on the front and back. This laminate was vacuum laminated using a vacuum laminator for manufacturing a solar cell module 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 70 KPa. After cooling, the glass and ETFE were peeled off to obtain a "sealing material sample". Regarding the thickness of this "encapsulating material sample", the film thickness at the center portion and the location 2 cm from the corner toward the center, and the film thicknesses at the above two points were measured with a digital film thickness meter. The test was performed 3 times. According to the knowledge of the inventor of the present application, in order for the black encapsulant sheet to satisfactorily exhibit the function as a light-shielding layer in the micro LED, the film thickness difference between the above two locations is within 10% at the maximum. Is essential. As a result of the above test, the film thickness difference between the central portion and the portion 2 cm from the corner was within 10 μm (7%) at the maximum.

<Evaluation example 2: Uniformity of visible light transmittance>
Regarding the "encapsulating material sample" whose film thickness uniformity was measured in the above <Evaluation Example 1>, visible light having a wavelength of 380 nm to 780 nm at the center portion and a location 2 cm from the corner toward the center, and at the above two points. The average of the spectral transmittances measured by JASCO Corporation V-670 was calculated. The test was performed 3 times. According to the knowledge of the inventor of the present application, in order for the black encapsulant sheet to satisfactorily exhibit the function as a light-shielding layer in the micro LED, the difference in the transmittance of the visible light at the above two locations is at most 2 It is essential that it is within%. As a result, the difference in the transmittance of visible light between the central part and the part 2 cm from the corner was within 1.2% at the maximum.

The results of Evaluation Example 1 and Evaluation Example 2 show that the self-luminous display 100 (100B) of the present invention having the layer structure shown in FIG. 2 in which black encapsulant sheets are laminated has the conventional structure shown in FIG. This is proof that it has the same optical characteristics as the light emitting display 100C.

From the above, the self-luminous display body of the present invention has a simplified layer structure while maintaining the image display quality of the conventional self-luminous display body including the light-shielding layer. It is clear that it can contribute to the improvement of productivity.

1 Black encapsulant sheet 2 Transparent optical layer 3, 3A, 3B Adhesive layer 4 Light-shielding layer 10 LED element (light emitting element)
11 LED light emitting chip 12 Resin cover 20 Wiring board 21 Support board 22 Wiring part 23 Handa layer 30 LED module (light emitting module)
100, 100A, 100B, 100C Micro LED display device (self-luminous display)

Claims (10)

A light emitting module in which multiple light emitting elements are mounted on a wiring board,
Using an olefin resin as a base resin, the CIE color coordinates measured according to JISZ8701-1999 with a C light source and a viewing angle of 2 deg are -1.0 ≤ a ^* ≤ 2.5 and -1.0 ≤ b ^*. For the L ^* value, a black encapsulant sheet having a color in the range of ≦ 15.0 and 0 ≦ L ^* ≦ 50, and
With a transparent optical layer,
The black encapsulant sheet covers the surface of the light emitting element and the wiring board and is laminated on the light emitting module.
The transparent optical layer is a self-luminous display body laminated on the black encapsulant sheet. The black encapsulant sheet contains carbon black, and the content of the carbon black in the resin component of the black encapsulant sheet is 0.0001% by mass or more and 0.08% by mass or less. , The self-luminous display according to claim 1. The black encapsulant sheet contains a dispersant composed of one or more kinds of metal soaps, and the content of the dispersant in the resin component of the black encapsulant sheet is 0.00002 mass%. The self-luminous display according to claim 1 or 2, which is 0.002% by mass or less. The black encapsulant sheet has a melt viscosity (η * 1) of 1.0 × 10 ³ poise at a shear rate of 2.43 × 10 sec ^-1 measured at a temperature of 120 ° C. by a method according to JIS K7199. The self-luminous display according to any one of claims 1 to 3, which is 1.0 × 10 ⁵ poise or less. The self-luminous display according to any one of claims 1 to 4, wherein the black encapsulant sheet has a bicut softening point of more than 60 ° C and 100 ° C or less. The black encapsulant sheet is a multilayer film having a three-layer structure consisting of a skin layer, a core layer, and a skin layer, and the black pigment is contained only in the core layer, and the black pigment is contained in any of the skin layers. The self-luminous display according to any one of claims 1 to 5, which does not contain. The method according to any one of claims 1 to 6, wherein the support substrate of the wiring board is a glass epoxy-based hard substrate, and the surface color of the support substrate on the LED element mounting surface side is a color other than white and black. Self-luminous display. The self-luminous display according to any one of claims 1 to 7, wherein the light emitting element is an LED element. The LED element has an LED light emitting chip and a resin cover that covers the LED light emitting chip.
The width and depth of the LED element are both 300 μm or less, and the height is 200 μm or less.
The self-luminous display according to claim 8, wherein the arrangement interval of each of the LED elements is 0.03 mm or more and 100 mm or less. The width and depth of the LED element are both 50 μm or less, and the height is 10 μm or less.
The self-luminous display according to claim 9, wherein the arrangement intervals of the LED elements are 0.05 mm or more and 5 mm or less.

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