JP7444309B2 - Self-luminous display - Google Patents

Description

The present invention relates to a self-luminous display. 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 a unique design concept.

BACKGROUND ART As a next-generation display device to replace various liquid crystal display devices, development of self-luminous display devices typified by micro LED televisions is progressing (see Patent Document 1).

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

In many self-luminous displays, a light-shielding layer made of a black resin film 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 to prevent light reflected from a substrate, etc., on which a light-emitting element serving as a light source is mounted in a self-luminous display from having an adverse effect on the quality of displayed images. .

Japanese Patent Application Publication No. 2018-14481 Japanese Patent Application Publication No. 2014-148584 Japanese Patent Application Publication No. 2015-197543

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

Based on our unique design philosophy, the present inventors replaced the transparent encapsulant placed on the substrate on which the light-emitting elements serving as the light source are mounted in conventional self-luminous displays with black encapsulant. The present inventors have come to the conclusion that by using a light-shielding material, the layer structure of a self-luminous display including a light-shielding layer can be made simpler than before, 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 board, a black encapsulant sheet that uses olefin resin as a base resin and has a visible light transmittance of 5% to 70%, and a transparent optical layer. , the black encapsulant sheet covers the surfaces of the light emitting element and the wiring board and is laminated on the light emitting module, and the transparent optical layer is laminated on the black encapsulant sheet. A self-luminous display body.

According to the invention (1), the layer structure of a self-luminous display including a light-shielding layer can be made simpler than that of a conventional self-luminous display. This makes it possible to improve the productivity of self-luminous displays such as micro LED televisions.

(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), wherein the content is 0.8% by mass or less.

In the invention (2), since 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 little unevenness 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 made of one or more 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), wherein the content is 00001% by mass or more and 0.002% by mass or less.

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

(4) The support substrate of the wiring board is a glass epoxy hard substrate, and the color of the surface of the support substrate on the side where the LED element is mounted is a color other than white or black (1) to (3) The self-luminous display according to any one of the above.

The invention (4) provides a self-luminous display such as a micro LED display device using a colored glass epoxy substrate, typically brown, as a support substrate, in which the support substrate disposed inside is brown, for example. It is possible to effectively reduce deterioration in display quality due to reflected light from the substrate, which tends to be a problem especially when the display is a colored surface such as a substrate.

(5) The self-luminous display 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, typified by micro LED televisions, which are expected to be the mainstream of next-generation monitors. Thereby, it is possible to obtain a self-luminous LED display device that is more productive than conventional products.

(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.

The invention (6) uses the self-luminous display body of (5) in a high-definition dot matrix display device, etc. in which LED elements are densely mounted using a chip-on-board method in which a large number of LED chips are directly mounted on a substrate. It was applied. Thereby, a high-definition LED display device with excellent productivity can be obtained.

(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 LED element is 0.05 mm or more and 5 mm or less, (6 ) The self-luminous display body described in ).

Invention (7) is an application of the self-luminous display body of (5) to "micro LED television", which has been developed in recent years and is expected to be a next-generation video display device. Thereby, an ultra-high definition LED display device with excellent productivity can be obtained.

According to the present invention, the layer structure of a self-luminous display including a light-shielding layer can be made simpler than that of a conventional self-luminous display, and can be used for various self-luminous displays such as micro LED televisions. It can contribute to improving the productivity of display bodies.

FIG. 1 is a plan view of an image display surface for a self-luminous display of the present invention and a partially enlarged plan view thereof. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and is a diagram schematically showing the layer structure of the self-luminous display of the present invention. FIG. 2 is a diagram schematically showing the layer structure of a black encapsulant sheet according to the present invention constituting the self-luminous display of FIG. 1. FIG. FIG. 2 is a perspective view of an LED element constituting the LED module for the self-luminous display of FIG. 1. FIG. 2 is a diagram schematically showing the layer structure of a conventional self-luminous display.

<Self-luminous display>
First, the term "self-luminous display" in this specification refers to a display device typified by the micro LED television exemplified above, and is a display device for visual information such as text, images, and moving images. In this display device, a large number of minute light emitting elements are mounted in a matrix on a wiring board, and each light emitting element is selectively caused to emit light by a light emission control means connected to the light emitting element, thereby displaying the above visual information. This is a display device that can display images directly on a display screen by blinking light-emitting elements.

The "self-luminous display" of the present invention can be particularly preferably implemented as an LED display device using an LED element as a light emitting element. Moreover, it is more preferable that the LED element in this case is a "micro-sized LED element". In this specification, "micro-sized LED element" specifically refers to the width (W) and depth (D) of the entire light emitting element including the LED light emitting chip and the resin cover that covers it. ) are all 300 μm or less, and the height (H) is 200 μm or less (see FIG. 4).

Further, regarding the size of this "micro-sized LED element", it is more preferable that the width and depth are both 50 μm or less, and the height is 10 μm or less. Note that this size range is the standard size range of LED elements mounted in micro LED televisions, which have been developed in recent years and are expected to become mainstream in next-generation televisions. Hereinafter, in this specification, micro-sized LED elements each having a width and depth of 50 μm or less and a height of 10 μm or less are arranged at a pitch of several 1000×several 1000 at a pitch of several μm to several tens of μm. A self-luminous display device arranged in a matrix in a number greater than 100% is called a "micro LED display device."

In the following, the present invention will be described while taking up an embodiment in which the "self-luminous display" is a "micro LED display" as a particularly preferable specific example of various embodiments of the present invention. A detailed explanation will be given. However, the technical scope of the present invention is not limited to application only to "micro LED display devices". This technology is also applicable to all "self-luminous display bodies" as defined above.

[Micro LED display device]
FIG. 1 is a front view and a partially enlarged view (100A) of a micro LED display device 100, which is an embodiment of a self-luminous display according to the present invention. Further, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and is a drawing for explaining the layer structure of the micro LED display device 100 (100B) shown in FIG. This micro LED display device 100 (100B) is a "light-emitting module" for a self-luminous display in which a large number of minute-sized "LED elements 10" are mounted on a wiring board 20 as "light-emitting elements". This is a self-luminous display device equipped with an 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 bonded.

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 coated with the LED element 10, and the visible light transmittance is 5% or more and 70% or less. Black encapsulant sheets 1, which are resin sheets, are laminated. Further, this 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. It is preferable. Because the black encapsulant sheet 1 is in close contact with the side surface of the LED element 10 due to its excellent molding properties, light is emitted from the side surface, especially when the LED element is of a type that emits light from the side surface as well. It is possible to prevent the color balance from being disrupted and a display with poor color reproducibility due to light being irradiated onto the glass epoxy substrate and the color of the substrate being reflected and leaking from the display surface. Furthermore, in the light emitting module disclosed in Patent Document 3, a through hole was formed in the light shielding layer directly above the LED element, but in a self-luminous display such as a micro LED TV, the height is higher than that of a liquid crystal TV. It is possible to apply a light-shielding layer that does not have an opening in order to enable luminance to emit light and improve color reproducibility. The details of the composition, layer structure, etc. of the black encapsulant sheet 1 will be described later.

In the micro LED display device 100 (100B), as also shown in FIG. (display surface side).

Here, as disclosed in Patent Document 3 etc., in the conventional micro LED display device 100C, as shown in FIG. They were laminated, and a light shielding layer 4 was separately disposed on the surface thereof with an adhesive layer 3A interposed therebetween. A transparent optical layer 2 similar to the above was further laminated on the surface of the light shielding layer 4 via an 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 encapsulant 1C in the conventional micro LED display device 100C shown in FIG. The optical functions of the present invention are made to be carried out only by the black encapsulant sheet 1, thereby simplifying the layer structure of the entire display device while retaining 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 applied to the joined LED modules in the same manner as described above. By stacking them, it is possible to configure an LED module for a large self-luminous display, and furthermore, a large micro LED display device. In this case, the excellent uniformity of the film thickness after hot pressing of the black encapsulant sheet 1 maintains the uniformity of the display surface at the joint between the individual LED modules to be joined, and The present invention can also contribute to improving the image quality of micro-LED display devices.

(Method for manufacturing micro LED display device)
The micro LED display device 100 (100B) is a laminated structure in which an LED module 30 for a self-luminous display in which an LED element 10 is mounted on a wiring board 20, a black encapsulant sheet 1, and a transparent optical layer 2 are laminated. It can be manufactured by integrating the laminate into a body by hot pressing. Incidentally, it is preferable that some of the laminated members be bonded in advance with an adhesive before the above-mentioned hot press processing, if necessary. For example, it is preferable to manufacture the micro LED display device 100 by adhering the transparent optical layer 2 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 according to the present invention is constructed by mounting an LED element 10 on a wiring board 20 in which a wiring part 22 is formed on a support substrate 21. Ru.

As shown in FIG. 2, the wiring board 20 has a wiring part 22 formed of a metal such as copper or other conductive material on the surface of a support board 21 in a form that allows conduction with the LED element 10. It is a circuit board made up of As the supporting substrate 21, a conventionally known hard glass epoxy substrate can be used as an electronic circuit substrate.

Here, the surface of the glass epoxy hard substrate usually has a brownish color. Conventionally, in a micro LED display device, the display quality has deteriorated due to the light reflected on the brown-colored surface of the support substrate disposed inside transmitting to the outside on the display surface side. There were cases where a decline was caused. In order to prevent such problems, in the conventional micro LED display device 100C (see FIG. 5), a light shielding layer 4 as shown in the figure is placed on a transparent encapsulant sheet 1D that transmits almost all visible light. It was laminated separately. In contrast, in the micro LED display device 100 (100B) (see FIG. 2) of the present invention, as a sealing material that also functions as the light shielding layer 4 in the conventional configuration, the transmittance of visible light is 5% or more and 70%. A black encapsulant sheet 1 as shown below is arranged. Therefore, the present invention exhibits particularly advantageous effects in a micro LED display device that uses, as the support substrate 21, a glass epoxy hard substrate having a surface with a color representative of brownish color other than white or black.

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

Although there is no particular limitation on the size of the LED module 30, it is generally preferable to have a diagonal length of about 50 inches to 200 inches from the viewpoint of cost performance. Furthermore, as described above, a plurality of LED modules 30 for self-emissive displays are joined in a matrix on the same plane to constitute a light-emitting surface of a self-emissive display such as a large micro LED display device. be able to. For example, 100 x 100 LED modules 30 each having a diagonal length of 6 inches can be joined vertically and horizontally to form a micro LED television with a large screen having a diagonal length of 600 inches.

(LED element)
The LED element 10 that is mounted on the wiring board 20 and constitutes the LED module 30 for a self-luminous display 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. A structure 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 the P-type and N-type electrodes are provided on one side of the element have been proposed. Although the LED element 10 having any structure can be used in the LED display device 100 (100B) of the present invention, an LED element such as the one disclosed as a "chip-shaped electronic component" in JP-A No. 2006-339551, Microscopic LED elements can be particularly preferably used. The LED element disclosed in this document is said to have a width x depth x height of approximately 25 μm x 15 μm x 2.5 μm.

It is preferable that the LED element 10 includes an LED light emitting chip 11 and a resin cover 12 covering it. Further, as the resin cover 12, organic insulating materials such as epoxy resin, silicone resin, and polyimide resin are used, and among these, epoxy resin is particularly preferably used. The resin cover 12 made of epoxy resin not only protects the LED light emitting chip 11 from physical impact, but also protects the inside of 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 the role of suppressing total reflection of light and increasing the luminous efficiency of the LED element 10. The black encapsulant sheet 1 is preferable as the encapsulant to be mounted on the micro LED display device 100 (100B) in that it is formed of an olefin resin that has excellent adhesion to epoxy resin.

In the self-luminous display of the present invention, the LED element includes an LED light-emitting chip and a resin cover covering it, and has a width and depth of 300 μm or less and a height of 200 μm or less. LED elements of the same size 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, in the self-luminous display of the present invention, the LED element includes an LED light-emitting chip and a resin cover covering it, and the width and depth are both 50 μm or less, and the height is 50 μm or less. More preferably, an LED element having an extremely small size of 10 μm or less can be 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 manner of mounting an LED element is also a standard manner of mounting an LED element in a 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 by forming a film of an encapsulant composition having an olefin resin such as polyethylene as a base resin. , a sheet-like member having a "black" color.

Here, "black" in this specification means that the CIE color coordinates measured in accordance with JIS Z8701-1999 using a C light source and a viewing angle of 2 degrees are -1.0≦a ^* ≦2.5 and -1 The range is .0≦b ^* ≦15.0, and the L ^* value refers to the color tone in the range of 0≦L ^* ≦50.

The black encapsulant sheet 1 may be a single-layer film, but as shown in FIG. Preferably, it is a film. The term "multilayer film" as used herein refers to a film or sheet having a structure including a skin layer formed on at least one of the outermost layers, preferably both outermost layers, and a core layer that 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 added 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. Thereby, it is possible to avoid contamination of the rubber roll, embossing roll, cooling roll, guide roll, etc. of the film forming apparatus 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. Further, when the LED element to be covered is an extremely small LED element with 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 external impact. On the other hand, when the thickness of the encapsulant sheet is 1000 μm or less, sufficient moldability can be exhibited. Specifically, during hot press processing with the LED element covered, the resin constituting the encapsulant sheet sufficiently wraps around the irregularities on the surface of the LED module to achieve good lamination with no gaps. can.

The black coloring agent used to impart an appropriate color to the black encapsulant sheet 1 is preferably a pigment-based material. For example, carbon black, which is commonly used as a black pigment, can be cited as an example of a preferable pigment. When coloring for display purposes, a black color is often created by combining multiple dyes, but in this case, if the pressure is uneven during adhesive lamination, color unevenness is likely to occur. In addition, as a durability test for displays, it is necessary to perform a durability test under an environment of 85°C 85% or 60°C 90%, but in the case of a pigment-based display, pigment deterioration (fading deterioration) tends to occur, so it is recommended to use a pigment-based display. is preferred. However, if it is necessary to lower the transmittance of a specific wavelength in order to expand the color range, 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 necessary blackness when the carbon black content is less than 0.0001% by mass, the thickness of the encapsulant sheet must be greater than necessary to maintain the original sealing function. It becomes necessary to do so. Further, if the content exceeds 0.08% by mass, the light from the LED cannot be transmitted appropriately, making it 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.

Moreover, it is more preferable to add a dispersant to the black sealing material sheet 1. Various metal soaps can be used as the dispersant. Moreover, as a dispersant, in addition to metal soap, it is also possible to use a low amount of polyethylene wax or the like. Specific examples of preferred dispersants include lithium stearate, magnesium stearate, calcium stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, calcium ricinoleate, barium ricinoleate, zinc ricinoleate, Examples include zinc octylate. Among them, calcium stearate, zinc stearate, zinc laurate, etc. are preferred from the viewpoint of the melting point of the resin. In particular, when calcium stearate, which is often contained in ordinary polyethylene resins, is applied as a dispersant, compatibility may deteriorate. It can be used preferably.

Here, when forming a sheet with concealment properties, there is usually little need to consider streaks such as die lines during film formation, but as with black encapsulant sheet 1, the visible light transmittance is 5%. When forming a sheet with the above-mentioned transparency, it is essential to improve the dispersibility of the pigment. If the amount added is small, the dispersion effect will be weakened, and if the amount added is too large, it will cause slippage during film formation. Therefore, the content of the above-mentioned dispersant in the resin component of the encapsulant composition is It is preferably at least 0.002% by mass. If the content of the dispersant is less than 0.00002% by mass, the dispersibility of the pigment decreases, resulting in variations in coloring density, and, for example, stripes appear on the surface, making it difficult to use for self-luminous displays. If the content exceeds 0.002% by mass, it may be difficult to maintain a constant film thickness due to screw slippage during film formation. Increased risk of difficulties. On the other hand, by adding a dispersant within the above range, the dispersibility of the pigment can be sufficiently improved while preventing the screw from slipping during film formation.

In addition, in the black encapsulant sheet 1, in order to promote good dispersion of the pigment, it is important to combine it with an antioxidant. It is preferable to add it to the resin component at a rate of about 200 to 800 ppm.

In the self-luminous display of the present invention, the "melt viscosity (η*1) at a shear rate of 2.43 x 10 sec ^-1 measured at a temperature of 120°C" of the black encapsulant sheet 1 is 1 The melt viscosity is preferably .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. In addition, the above-mentioned melt viscosity in this specification refers to the melt viscosity measured by a method based on JIS K7199.

By setting the above-mentioned "melt viscosity" to 1.0 x 10 ³ poise or more, it is possible to prevent the resin from extruding due to excessive flow during hot press processing of the encapsulant sheet or from lateral stress on the LED element. The occurrence of poor light emission can be sufficiently suppressed, and the uniformity of the film thickness of the encapsulant sheet after the hot press processing can also be maintained well. 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 thickness. This is because if the film thickness at the center of the black encapsulant sheet 1 differs even slightly from the film thickness at the edges, the encapsulant sheet becomes lens-shaped, which affects the display quality of the micro LED display device. This is because it may have an undesirable effect.

On the other hand, by setting the above-mentioned "melt viscosity" to 1.0×10 ⁵ poise or less, the moldability of the encapsulant sheet during hot press processing can be maintained well.

Here, the MFR value, which has conventionally been widely adopted as a guideline for the fluidity of encapsulant sheets, is measured at 190°C when measured in accordance with JIS K6922, but this temperature is actually The temperature differs from the temperature at which a sealant sheet for a self-luminous display melts during hot press processing. As shown later in Examples, even if the MFR value is within an appropriate value range, if the above-mentioned "melt viscosity" exceeds a predetermined value, necessary moldability may not be ensured. As an index for controlling the fluidity of the resin during hot press processing, instead of MFR, the shear modulus at a temperature of 120°C, that is, the shear rate 2. By using the melt viscosity (η*1) at 43 x 10 sec-1 as an index for optimizing the physical properties of the base resin, we can create a more effective and precise resin that is more in line with the actual usage of the encapsulant sheet. It is possible to obtain indicators related to selection.

Further, in the self-luminous display of the present invention, the Vicat softening point of the black encapsulant sheet 1 is preferably greater than 60°C and less than 100°C, more preferably greater than or equal to 70°C and less than 90°C. preferable. By setting the Vicat softening point of the black encapsulant sheet 1 to over 60°C, the occurrence of blocking in the manufacturing process of a self-luminous display using the encapsulant sheet is more reliably suppressed, and the self-luminous display is produced. It can contribute to improving the body's productivity. On the other hand, by setting this temperature range to 100° C. or lower, it is possible to sufficiently maintain moldability required for a sealing material sheet for a self-luminous display.

Further, it is preferable to optimize the Vicat softening point of the sealing material sheet more precisely depending on the melting point of the sealing material sheet. Specifically, if the melting point of the encapsulant sheet is in a relatively low range of 50 to 70 degrees Celsius, the Vicat softening point should be set to 60 to 70 degrees Celsius in order to suppress excessive flow during hot press processing. It is preferable to set it as the range below. Further, when the melting point is in a relatively high range of 70°C or higher, it is preferable that the Vicat softening point is in the range of 70°C to 100°C in order to maintain good moldability during hot press processing. In addition, the "Vicat softening point" of the encapsulant sheet in this specification refers to the encapsulant formed into a sheet by a molding method such as extrusion melt molding from an encapsulant composition containing a resin component and other additives. This refers to the value measured based on ASTM D1525 of the Vicat softening point at a stage after the sheet has been formed into a sheet.

From another perspective, in the self-luminous display 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 will be slow, and the sheet extruded from the extruder will be sticky, making it difficult to peel it off with a cooling roll, making it difficult to seal. It becomes difficult to obtain material sheets. Furthermore, the sealing material sheet becomes sticky, causing blocking and making it difficult to feed out the sheet. On the other hand, if the durometer A hardness exceeds 95, the molding properties will deteriorate and the ability to follow the irregularities of the LED element will become insufficient.

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

In addition, "MFR" of the encapsulant sheet in this specification refers to the encapsulant sheet obtained by forming an 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 completion of sheet formation is a value measured in accordance with JIS K7210 at 190° C. and a load of 2.16 kg. Regarding the MFR when the encapsulant sheet is a multilayer film, the measurement is carried out by the above process while all the layers are in a multilayered state, and the obtained measurement value is used for the multilayer encapsulant sheet. It shall be the MFR value.

The base resin of the encapsulant composition forming the black encapsulant sheet 1 can be selected from a wide range of olefin thermoplastic resins. Among these, polyethylene resins such as low density polyethylene resin (LDPE), linear low density polyethylene resin (LLDPE), and metallocene linear low density polyethylene resin (M-LLDPE) can be preferably used. In this specification, the term "base resin" refers to a resin having the highest content ratio among the resin components of the resin composition in a 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. I can do it. 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, etc. 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 crosslinking treatment.

In the sealing material composition, a silane copolymer (hereinafter also referred to as "silane-modified polyethylene resin") obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer is optionally added. It is more preferable that each encapsulant composition contains a certain amount. The silane-modified polyethylene resin is obtained by graft polymerizing an ethylenically unsaturated silane compound as a side chain to a linear low density polyethylene resin (LLDPE) as a main chain. Such a graft copolymer has a high degree of freedom in silanol groups that contribute to adhesive strength, so it is difficult to bond the black encapsulant sheet 1 to other members in a self-luminous display such as the micro LED display device 100. can improve sexual performance. The content of this silane-modified polyethylene resin in the encapsulant composition is, for example, in the case of a multilayer encapsulant sheet consisting of a skin layer-core layer-skin layer, the content of the silane-modified polyethylene resin is 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 sealing material 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 resin is preferably about 1.0% by mass or more and 3.0% by mass or less. The preferable content range of the silane-modified polyethylene resin in the above-mentioned sealing material composition is based on the premise that the above-mentioned amount of silane modification is within this range, and may be finely adjusted as appropriate according to fluctuations in the amount of modification. is desirable.

By using silane-modified polyethylene resin as a component of the encapsulant composition for self-luminous displays, it has excellent strength and durability, as well as weather resistance, heat resistance, water resistance, light resistance, and wind pressure resistance. , has excellent hail resistance and other properties.Furthermore, it has extremely excellent heat fusion properties that are unaffected by the manufacturing conditions such as heat compression bonding used to manufacture self-luminous displays, and can be used stably and at low Self-luminous displays suitable for various uses can be manufactured at low cost.

The black encapsulant sheet 1 is preferably a thermoplastic encapsulant that does not require crosslinking treatment after film formation. As such an encapsulant sheet that does not require crosslinking treatment, a "weakly crosslinked encapsulant" made by weakly crosslinking a polyethylene encapsulant composition can also be used. "Weak crosslinking" is a crosslinking treatment technology related to the method for manufacturing a sealing material whose details are disclosed in International Publication No. 2011/152314, and is a very weak crosslinking technique that maintains the gel fraction at 0%. This is a technique for forming a film of a sealing material composition while progressing. In this specification, a weakly crosslinked encapsulant formed into a film through this weak crosslinking treatment is referred to as a "weakly crosslinked encapsulant." Note that the weakly crosslinked encapsulant has undergone weak crosslinking treatment at the time of film formation, and substantially no crosslinking agent remains after film formation. Therefore, a separate crosslinking treatment is not necessary during the manufacturing process of the self-luminous display.

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

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

<Manufacture of encapsulant sheet for self-luminous display>
The following sealing material composition was prepared using a φ30 mm extruder for the first layer (skin layer), a φ30 mm extruder for the second layer (core layer), and a φ30 mm extruder for the third layer (skin layer), with a layer ratio of 1: In a 3:1 configuration, three layers of molten resin, skin layer-core layer-skin layer, were extruded using a film molding machine with a 300 mm wide T-die at an extrusion temperature of 210°C and a take-off speed of 1.1 m/min. , and formed into a sheet with a film thickness of 150 μm to produce encapsulant sheets for each example and comparative example. Regarding the cooling roll directly below the T-die and the rubber roll, a chrome-plated cooling roll with a surface roughness Rz of 1.5 μm was used as the cooling roll, and a silicone rubber roll with a hardness of 70 degrees was used as the rubber roll.
As a sealant composition for the first layer (skin layer), 100 parts by mass of the following "Base Resin 1", 5 parts by mass of the following "Additive Resin 1 (weathering agent masterbatch)", Additive resin 2 (silane-modified polyethylene resin) was mixed in a proportion of 20 parts by mass.
As a sealant composition for the second layer (core layer), 100 parts by mass of the following "Base Resin 1", 5 parts by mass of the following "Additive Resin 1 (weathering agent masterbatch)", 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 a sealant composition for the third layer (skin layer), 100 parts by mass of the following "Base Resin 1", 5 parts by mass of the following "Additive Resin 1 (weathering agent masterbatch)", Additive resin 2 (silane-modified polyethylene resin) was mixed in a proportion of 20 parts by mass.
Base resin 1
: Metallocene-based linear low-density polyethylene 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 min at 190°C.
Additive resin 1 (weathering agent masterbatch)
: KEMISTAB62 (HALS): 0.6 parts by mass for 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 min 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)
: ² parts by mass of vinyltrimethoxysilane and a radical generator (reactive A silane-modified polyethylene resin obtained by mixing with 0.15 parts by mass of dicumyl peroxide as a catalyst), melting and kneading at 200°C. This additive resin 2 has a density of 0.901 g/cm ³ and an MFR of 1.0 g/10 min.
Additive resin 3: (black masterbatch)
40 parts by mass of carbon black with a density of 0.91 g/cm3 and an MFR of 5.0 g/10 min, 2 parts by mass of metal soap (calcium stearate), and linear low-density polyethylene (LLDPE with a density of 0.910 g/cm3). ) A black masterbatch having 60 parts by weight.

<Evaluation example 1: Film thickness uniformity>
A laminate with a structure in which 50 μm untreated ETFE was laminated as a release film on the front and back sides of the sealing material sheet of the example cut to 30 x 30 cm, and then 30 x 30 cm glass with a thickness of 3 mm was laminated on the front and back sides. This laminate was vacuum laminated using a vacuum laminator for solar cell module manufacturing under conditions of a temperature of 150° C., evacuation time of 5 minutes, press holding time of 10 minutes, and upper chamber pressure of 70 KPa. After cooling, the glass and ETFE were peeled off to obtain a "sealing material sample." The thickness of this "sealing material sample" was measured using a digital film thickness meter at two points: the center portion and a point 2 cm from the corner toward the center. The test was conducted three times. According to the findings of the inventor of the present application, in order for the black encapsulant sheet to perform well as a light-shielding layer in a micro-LED, the difference in film thickness between the above two locations must be within 10% at most. This is essential. As a result of the above test, the difference in film thickness between the center and 2 cm from the corner was within 10 μm (7%) at most.

<Evaluation Example 2: Uniformity of visible light transmittance>
Regarding the "sealing material sample" whose film thickness uniformity was measured in <Evaluation Example 1> above, visible light with a wavelength of 380 nm to 780 nm at the center part and a point 2 cm from the corner toward the center, and the above two points. The average spectral transmittance measured using JASCO V-670 was calculated. The test was conducted three times. According to the findings of the inventors of the present invention, in order for the black encapsulant sheet to function well as a light-shielding layer in a micro-LED, the difference in visible light transmittance between the two locations must be at most 2. Must be within %. As a result, the difference in visible light transmittance between the center and 2 cm from the corner was within 1.2% at most.

The results of Evaluation Example 1 and Evaluation Example 2 show that the self-luminous display body 100 (100B) of the present invention having the layered structure shown in FIG. This proves that the light-emitting display body 100C has optical properties equivalent to those of the light-emitting display body 100C.

From the above, the self-luminous display of the present invention has a simplified layer structure while maintaining the image display quality of the conventional self-luminous display that includes a light shielding layer. It is clear that it can contribute to improving 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 section 23 Solder layer 30 LED module (light emitting module)
100, 100A, 100B, 100C Micro LED display device (self-luminous display)

Claims (11)

A light emitting module in which a plurality of light emitting elements are mounted on a wiring board;
A black encapsulant sheet whose base resin is olefin resin,
a transparent optical layer;
The black encapsulant sheet contains a phenolic antioxidant or a phosphorus antioxidant, and the content of the antioxidant in the resin component is 200 ppm or more and 800 ppm or less, and The element and the surface of the wiring board are coated and laminated on the light emitting module,
The transparent optical layer is laminated on the black encapsulant sheet,
Self-luminous display. A light emitting module in which a plurality of light emitting elements are mounted on a wiring board;
A black encapsulant sheet whose base resin is olefin resin,
a transparent optical layer;
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, in which only the core layer contains a black pigment, and each of the skin layers contains a black pigment. does not contain, and is laminated on the light emitting module by coating the surface of the light emitting element and the wiring board,
The transparent optical layer is laminated on the black encapsulant sheet,
Self-luminous display. The black encapsulant sheet has a film thickness difference of 10 μm or less as measured by the film thickness uniformity test described below.
A self-luminous display according to claim 1 or 2 .
(Film thickness uniformity test)
A 50 μm untreated ETFE was laminated as a release film on the front and back sides of an encapsulant sheet cut to 30 x 30 cm, and then 30 x 30 cm and 3 mm thick glass was further laminated on the front and back sides to form a laminate. The body is vacuum laminated using a vacuum laminator for manufacturing solar cell modules under the conditions of a temperature of 150° C., evacuation time of 5 minutes, press holding time of 10 minutes, and upper chamber pressure of 70 KPa. After cooling, the glass and ETFE are peeled off to obtain a "sealing material sample." The thickness of this "sealing material sample" is measured at two points, the center part and a 2 cm point from the corner toward the center, using a digital film thickness meter. 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. ,
A self-luminous display according to any one of claims 1 to 3. The black encapsulant sheet contains a dispersant made of one or more metal soaps, and the content of the dispersant in the resin component of the black encapsulant sheet is 0.00002% by mass. 0.002% by mass or less,
A self-luminous display according to any one of claims 1 to 4. 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 based on JIS K7199. more than or equal to 1.0×10 ⁵ poise or less;
A self-luminous display according to any one of claims 1 to 5. The black encapsulant sheet has a Vicat softening point of more than 60°C and less than 100°C.
A self-luminous display according to any one of claims 1 to 6. The support substrate of the wiring board is a glass epoxy hard substrate, and the color of the surface of the support substrate on the side where the LED element is mounted is a color other than white or black.
A self-luminous display according to any one of claims 1 to 7 . The light emitting element is an LED element.
A self-luminous display according to any one of claims 1 to 8 . The LED element has an LED light emitting chip and a resin cover covering 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 arrangement interval of each of the LED elements is 0.03 mm or more and 100 mm or less,
The self-luminous display according to claim 9 . 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 of each of the LED elements is 0.05 mm or more and 5 mm or less,
The self-luminous display according to claim 10 .

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