Optical semiconductor element encapsulation sheet

Abstract

To provide an optical semiconductor device sealing sheet which is suitable for manufacturing self-luminous display devices, such as mini / micro LED display devices, with improved metal wiring anti-reflection capability and contrast and reduced color cast.SOLUTION: An optical semiconductor device sealing sheet 10 of the present invention comprises a diffusion layer 1 and an anti-reflection layer 2. A total light transmittance T1 of the diffusion layer 1 and a total light transmittance T2 of the anti-reflection layer 2 satisfy a condition expressed as T1>T2, and a haze value H1 of the diffusion layer 1 and a haze value H2 of the anti-reflection layer 2 satisfy a condition expressed as H1>H2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet for encapsulating optical semiconductor elements. More specifically, the present invention relates to a sheet suitable for encapsulating optical semiconductor elements of self-luminous display devices such as mini / micro LEDs. [Background technology]

[0002] In recent years, self-emitting display devices, such as mini / micro LED display devices (Mini / Micro Light Emitting Diode Displays), have been devised as next-generation display devices. Mini / micro LED display devices basically consist of a substrate on which a large number of tiny optical semiconductor elements (LED chips) are densely arranged, used as a display panel, with the optical semiconductor elements encapsulated in an encapsulant and a cover member such as a resin film or glass plate laminated on the outermost surface.

[0003] In self-luminous display devices such as mini / micro LED display devices, wiring (metal wiring) made of metal or metal oxide such as ITO is arranged on the display panel substrate, and an anti-reflection layer is sometimes used as a sealant to prevent reflection from the metal wiring (see, for example, Patent Document 1). In particular, in RGB mini / micro LED display devices in which optical semiconductor elements of three colors (RGB) are arranged alternately, the anti-reflection layer can also contribute to preventing RGB color mixing and improving contrast. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-204905 Summary of the Invention [Problem to be solved by the invention]

[0005] Mini / micro LED display devices have three colored optical semiconductor elements (RGB) arranged alternately, but the intensity of the RGB side light emission is different. Specifically, the side light emission of R is smaller than that of GB, which causes a problem called color cast, in which the color changes depending on the viewing angle.

[0006] The present invention was conceived under the circumstances described above, and an object of the present invention is to provide a sheet for encapsulating optical semiconductor elements that is suitable for producing self-emissive display devices such as mini / micro LED display devices, which have improved anti-reflection function and contrast of metal wiring while reducing color cast. Another object of the present invention is to provide an optical semiconductor device, a self-luminous display device, and an image display device that are equipped with the above-mentioned sheet for encapsulating an optical semiconductor element, and that have improved anti-reflection function and contrast of metal wiring while reducing color cast. [Means for solving the problem]

[0007] As a result of intensive research to achieve the above object, the inventors have found that by using a sheet for encapsulating optical semiconductor elements that includes a diffusion layer and an antireflection layer and in which the total light transmittance and haze value of the diffusion layer and the antireflection layer are controlled to have a specific relationship, it is possible to manufacture a self-emissive display device such as a mini / micro LED display device that has improved antireflection function and contrast for metal wiring and the like, while reducing color cast. The present invention was completed based on these findings.

[0008] That is, a first aspect of the present invention provides a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, i.e., an optical semiconductor element encapsulation sheet. The optical semiconductor element encapsulation sheet of the first aspect of the present invention includes a diffusion layer and an antireflection layer.

[0009] The configuration in which the optical semiconductor element encapsulation sheet according to the first aspect of the present invention includes a diffusion layer is preferable in terms of reducing color cast in mini / micro LED display devices. Furthermore, the configuration in which the optical semiconductor element encapsulation sheet according to the first aspect of the present invention includes an antireflection layer is preferable in terms of improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices. The layer that encapsulates the optical semiconductor element may be a diffusion layer or an antireflection layer, or the optical semiconductor element may be encapsulated by both the diffusion layer and the antireflection layer.

[0010] In the sheet for encapsulating optical semiconductor elements according to the first aspect of the present invention, the total light transmittance T1 of the diffusion layer and the total light transmittance T2 of the anti-reflection layer satisfy the relationship T1>T2, i.e., the total light transmittance of the diffusion layer is higher than the total light transmittance of the anti-reflection layer. This configuration is advantageous in terms of improving the anti-reflection function and contrast of metal wiring and the like in mini / micro LED display devices.

[0011] In the optical semiconductor element encapsulation sheet according to the first aspect of the present invention, the haze value H1 of the diffusion layer and the haze value H2 of the anti-reflection layer satisfy the relationship H1>H2, i.e., the haze value of the diffusion layer is higher than the haze value of the anti-reflection layer. This configuration is advantageous in terms of reducing color cast in mini / micro LED display devices.

[0012] In the sheet for encapsulating an optical semiconductor element according to the first aspect of the present invention, the haze value H1 of the diffusion layer is preferably 30 to 99.9%, which is advantageous in terms of reducing color cast in mini / micro LED display devices.

[0013] In the sheet for encapsulating optical semiconductor elements according to the first aspect of the present invention, the total light transmittance T2 of the antireflection layer is preferably 1 to 30%, which is advantageous in terms of improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices.

[0014] In the sheet for encapsulating optical semiconductor elements according to the first aspect of the present invention, the diffusion layer and the antireflection layer are preferably adjacent to each other. That is, the diffusion layer and the antireflection layer are preferably adjacent to each other and directly laminated to each other. This configuration is advantageous in terms of reducing color cast in mini / micro LED display devices. That is, if the diffusion layer and the antireflection layer are laminated via another layer structure, it becomes difficult to control the reflection and diffusion of light emitted from the optical semiconductor elements of the mini / micro LED display device, and it tends to be difficult to prevent color cast.

[0015] In one embodiment of the sheet for encapsulating optical semiconductor elements according to the first aspect of the present invention, the diffusion layer is preferably a resin layer, and the antireflection layer is preferably a resin layer. Also, the diffusion layer is preferably an adhesive layer, and the antireflection layer is preferably an adhesive layer. These configurations are preferred in that the diffusion layer and / or the antireflection layer fill the gaps between the optical semiconductor elements arranged on the substrate of the mini / micro LED display device without gaps, providing excellent gap absorption and preventing display unevenness.

[0016] A second aspect of the present invention provides an optical semiconductor device comprising: a substrate; one or more optical semiconductor elements disposed on the substrate; and the sheet for encapsulating optical semiconductor elements according to the first aspect of the present invention, wherein the sheet for encapsulating optical semiconductor elements encapsulates the optical semiconductor elements. The optical semiconductor device according to the second aspect of the present invention is preferably a self-luminous display device. Furthermore, a third aspect of the present invention provides an image display device comprising the self-luminous display device.

[0017] The optical semiconductor device (preferably a self-luminous display device) according to the second aspect of the present invention and the image display device according to the third aspect of the present invention are manufactured using the sheet for encapsulating an optical semiconductor element according to the first aspect of the present invention, and therefore have improved anti-reflection function and contrast of the metal wiring while reducing color cast. [Effects of the Invention]

[0018] By using the optical semiconductor element encapsulation sheet of the present invention, it is possible to produce a self-luminous display device such as a mini / micro LED display device that has improved anti-reflection function and contrast of metal wiring while reducing color cast. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram (cross-sectional view) showing one embodiment of the sheet for encapsulating an optical semiconductor element of the present invention. [Figure 2] FIG. 2 is a schematic view (cross-sectional view) showing another embodiment of the sheet for encapsulating an optical semiconductor element of the present invention. [Figure 3] FIG. 3 is a schematic diagram (cross-sectional view) showing one embodiment of a self-luminous display device (mini / micro LED display device) of the present invention. [Figure 4] FIG. 4 is a schematic diagram (cross-sectional view) showing another embodiment of the self-luminous display device (mini / micro LED display device) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] A first aspect of the present invention provides a sheet for encapsulating an optical semiconductor element. The sheet for encapsulating an optical semiconductor element according to the first aspect of the present invention may be referred to as "the sheet for encapsulating an optical semiconductor element of the present invention."

[0021] The term "sheet for encapsulating optical semiconductor elements" refers to a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate. The optical semiconductor elements are not particularly limited as long as they are semiconductor elements that have a light-emitting function, and include light-emitting diodes (LEDs) and semiconductor lasers. In particular, a form used for encapsulating LED chips in self-emitting display devices such as mini / micro LED display devices in which multiple LED chips are arranged on a substrate is preferred.

[0022] The sheet for encapsulating an optical semiconductor element of the present invention includes a diffusion layer and an antireflection layer. The diffusion layer and the antireflection layer constituting the sheet for encapsulating an optical semiconductor element of the present invention may be referred to as the "diffusion layer of the present invention" and the "antireflection layer of the present invention", respectively.

[0023] The optical semiconductor element encapsulation sheet of the present invention may be composed of only a diffusion layer and an antireflection layer, or may further include layers other than the diffusion layer and the antireflection layer (other layers). Examples of other layers include a substrate, a release film (separator), a surface protection film, and a pressure-sensitive adhesive layer. The other layers can be disposed on the surface of the optical semiconductor element encapsulation sheet of the present invention or between any layers. For example, they may be disposed on the main surface of the diffusion layer, the main surface of the antireflection layer, or between the diffusion layer and the antireflection layer.

[0024] A second aspect of the present invention provides an optical semiconductor device comprising a substrate, one or more optical semiconductor elements disposed on the substrate, and the sheet for encapsulating optical semiconductor elements of the present invention, wherein the sheet for encapsulating optical semiconductor elements encapsulates the optical semiconductor elements. The optical semiconductor device of the second aspect of the present invention is preferably a self-luminous display device. Furthermore, a third aspect of the present invention provides an image display device comprising the self-luminous display device.

[0025] The optical semiconductor device according to the second aspect of the present invention, the self-luminous display device, and the image display device according to the third aspect of the present invention may be referred to as the "optical semiconductor device of the present invention," the "self-luminous display device of the present invention," and the "image display device of the present invention," respectively.

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these and is merely an example. 1 and 2 are schematic diagrams (cross-sectional views) showing an embodiment of the sheet for encapsulating an optical semiconductor element of the present invention. Figures 3 and 4 are schematic diagrams (cross-sectional views) showing an embodiment of the self-luminous display device (mini / micro LED display device) of the present invention.

[0027] In Fig. 1, optical semiconductor element encapsulation sheet 10 has a laminated structure in which diffusion layer 1 and antireflection layer 2 are laminated. In optical semiconductor element encapsulation sheet 10, diffusion layer 1 and antireflection layer 2 are adjacent to each other, that is, diffusion layer 1 and antireflection layer 2 are laminated in direct contact with each other. In Fig. 2, optical semiconductor element encapsulation sheet 11 has a laminated structure in which diffusion layer 1 and antireflection layer 2 are laminated via substrate S. That is, diffusion layer 1 and antireflection layer 2 are not in direct contact with each other, but are laminated via another layer.

[0028] In Fig. 3, a self-luminous display device (mini / micro LED display device) 20 includes a display panel in which a plurality of LED chips 5 are arranged on one surface of a substrate 3, and an optical semiconductor element encapsulation sheet 10 of the present invention. The LED chips 5 on the substrate 3 are encapsulated by an antireflection layer 2 of the optical semiconductor element encapsulation sheet 10. In Fig. 4, a self-luminous display device (mini / micro LED display device) 21 includes a display panel in which a plurality of LED chips 5 are arranged on one surface of a substrate 3, and an optical semiconductor element encapsulation sheet 10 of the present invention. The LED chips 5 on the substrate 3 are encapsulated by a diffusion layer 1 of the optical semiconductor element encapsulation sheet 10.

[0029] In this embodiment, a metal wiring layer 4 for sending light emission control signals to each LED chip 5 is laminated on the substrate 3 of the display panel. The LED chips 5 emitting light of red (R), green (G), and blue (B) are alternately arranged on the substrate 3 of the display panel via the metal wiring layer 4. The metal wiring layer 4 is made of a metal such as copper, and reflects external light, reducing the visibility of images. In addition, the light emitted by each LED chip 5 of each color (RGB) mixes, reducing contrast.

[0030] In this embodiment, each LED chip 5 arranged on the display panel is sealed without any gaps by the diffusion layer 1 and / or the anti-reflection layer 2. In other words, the layered structure of the diffusion layer 1 and / or the anti-reflection layer 2 can serve as a sealant for each LED chip 5.

[0031] In this embodiment, the diffusion layer 1 and / or the antireflection layer 2 encapsulate the LED chips 5 and the metal wiring layer 4 arranged on the display panel. The diffusion layer 1 has a higher total light transmittance than the antireflection layer 2. That is, the antireflection layer 2 has a lower total light transmittance than the diffusion layer 1, and thus has sufficient light-blocking properties. The optical semiconductor element encapsulation sheet 10, which has the antireflection layer 2 with high light-blocking properties, encapsulates the metal wiring layer 4, and therefore can prevent reflection by the metal wiring layer 4.

[0032] In this embodiment, the haze value of the diffusion layer 1 is higher than the haze value of the anti-reflection layer 2, so that the light emitted by the LED chip 5 can be sufficiently diffused and color cast, which varies depending on the viewing angle, can be suppressed. Each component will be described in detail below.

[0033] <Optical semiconductor element encapsulation sheet> In the optical semiconductor element encapsulation sheet of the present invention, the total light transmittance T1 of the diffusion layer of the present invention and the total light transmittance T2 of the antireflection layer of the present invention satisfy the relationship T1 > T2. That is, the total light transmittance of the diffusion layer of the present invention is higher than the total light transmittance of the antireflection layer of the present invention. This configuration is advantageous in terms of improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices. From the viewpoint of further improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices, it is preferable to satisfy the relationship T1 > 2T2, more preferably T1 > 3T2, even more preferably T1 > 4T2, and particularly preferably T1 > 5T2. Alternatively, it may satisfy the relationship T1 > 6T2, T1 > 7T2, T1 > 8T2, T1 > 9T2, T1 > 10T2, T1 > 11T2, T1 > 12T2, T1 > 13T2, T1 > 14T2, or T1 > 15T2. In addition, in order to ensure the brightness of the mini / micro LED display device, the relationship 1000T2>T1 or 500T2>T1 may be satisfied.

[0034] In the sheet for encapsulating optical semiconductor elements of the present invention, the difference (T1-T2) between the total light transmittance T1 of the diffusion layer of the present invention and the total light transmittance T2 of the antireflection layer of the present invention is preferably 30% or more, more preferably 35% or more, even more preferably 40% or more, particularly preferably 45% or more, or even 50% or more, from the viewpoint of further improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices. Furthermore, from the viewpoint of ensuring the brightness of the mini / micro LED display device, (T1-T2) may be 95% or less, or 92% or less.

[0035] In the sheet for encapsulating an optical semiconductor element of the present invention, the relationship between T1 and T2 can be controlled by the types and thicknesses of the resin layer and pressure-sensitive adhesive layer (described later) constituting the diffusion layer and antireflection layer, the types and amounts of the colorant and light-diffusing fine particles (described later), and the like.

[0036] In the optical semiconductor element encapsulation sheet of the present invention, the haze value H1 of the diffusion layer of the present invention and the haze value H2 of the antireflection layer of the present invention satisfy H1>H2, i.e., the haze value of the diffusion layer is higher than the haze value of the antireflection layer. This configuration is advantageous in terms of reducing color cast in mini / micro LED display devices. In order to more efficiently reduce color cast in mini / micro LED display devices, it is preferable that H1>1.1H2 be satisfied, more preferably H1>1.5H2, even more preferably H1>2H2, and particularly preferably H1>2.5H2. Alternatively, H1>3H2, H1>3.5H2, H1>4H2, H1>4.5H2, H1>5H2, H1>5.5H2, H1>6H2, H1>6.5H2, H1>7H2, H1>7.5H2, H1>8H2, H1>8.5H2, or H1>9H2 may be satisfied. Furthermore, in order to ensure visibility of mini / micro LED display devices, it is also possible to satisfy 100H2>H1 or 50H2>H1.

[0037] In the sheet for encapsulating optical semiconductor elements of the present invention, the difference (H1-H2) between the haze value H1 of the diffusion layer of the present invention and the haze value H2 of the antireflection layer of the present invention is preferably 1% or more, more preferably 4% or more, even more preferably 10% or more, particularly preferably 15% or more, and may even be 20% or more, from the viewpoint of more efficiently reducing color cast in mini / micro LED display devices. Furthermore, from the viewpoint of ensuring visibility of mini / micro LED display devices, (H1-H2) may be 95% or less, or 90% or less.

[0038] In the sheet for encapsulating an optical semiconductor element of the present invention, the relationship between H1 and H2 can be controlled by the types and thicknesses of the resin layer and pressure-sensitive adhesive layer (described later) that constitute the diffusion layer and antireflection layer, the types and amounts of the light-diffusing fine particles and colorant (described later), and the like.

[0039] The total light transmittance of the optical semiconductor element encapsulation sheet of the present invention (total light transmittance including the diffusion layer and antireflection layer) is not particularly limited, but from the viewpoint of further improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices, it is preferably 55% or less, more preferably 50% or less, even more preferably 45% or less, and particularly preferably 40% or less. Furthermore, from the viewpoint of ensuring the brightness of mini / micro LED display devices, the total light transmittance of the optical semiconductor element encapsulation sheet of the present invention is preferably 0.1% or more, more preferably 0.3% or more, even more preferably 0.5% or more, particularly preferably 0.7% or more, or may even be 0.8% or more.

[0040] The total light transmittance of the sheet for encapsulating an optical semiconductor element of the present invention can be measured by the method specified in JIS 7361, and can be controlled by the types and thicknesses of the resin layer and pressure-sensitive adhesive layer described below, the types and amounts of the colorant and light-diffusing fine particles described below, and the like.

[0041] The haze value of the optical semiconductor element encapsulation sheet of the present invention (the overall haze value including the diffusion layer and antireflection layer) is not particularly limited, but from the viewpoint of more efficiently reducing color cast in mini / micro LED display devices, it is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more, and may be 60% or more, 70% or more, 80% or more, or 90% or more, with a haze value of around 99.9% being the most effective in reducing color cast. The upper limit of the haze value of the optical semiconductor element encapsulation sheet is not particularly limited, and may be 100%.

[0042] The haze value of the sheet for encapsulating an optical semiconductor element of the present invention can be measured by the method specified in JIS 7136, and can be controlled by the types and thicknesses of the resin layer and pressure-sensitive adhesive layer described below, the types and amounts of the light-diffusing fine particles and colorant described below, and the like.

[0043] The thickness of the optical semiconductor element encapsulation sheet of the present invention (total thickness including the diffusion layer and antireflection layer) is preferably 10 to 600 μm, more preferably 20 to 550 μm, even more preferably 30 to 500 μm, and particularly preferably 40 to 450 μm or 50 to 400 μm, from the viewpoints of improving the antireflection function and contrast of metal wiring and the like in mini / micro LED display devices while more efficiently reducing color cast. When the optical semiconductor element encapsulation sheet of the present invention includes a substrate as another layer, the substrate is included in the thickness of the optical semiconductor element encapsulation sheet of the present invention, but the release film (separator) is not included in the thickness of the optical semiconductor element encapsulation sheet of the present invention.

[0044] The ratio of the thickness of the antireflection layer to the thickness of the diffusion layer (antireflection layer thickness / diffusion layer thickness) is not particularly limited and may be appropriately set so as to efficiently reduce color cast in the mini / micro LED display device while adequately sealing the light-emitting elements arranged on the display panel described below. Specifically, (antireflection layer thickness / diffusion layer thickness) may be, for example, about 0.1 to 3, preferably 0.15 to 3, and more preferably 0.2 to 3. It may also be, for example, about 0.1 to 3, preferably 0.1 to 2.5, and more preferably 0.1 to 2.

[0045] <Diffusion layer> The diffusion layer of the present invention is a layer having a function of diffusing light and is preferably composed of a resin layer. The diffusion layer of the present invention is not limited as long as it has a function of diffusing light, but preferably contains light-diffusing fine particles dispersed in the resin layer.

[0046] The haze value of the diffusion layer of the present invention is not particularly limited, but from the viewpoint of efficiently reducing color cast in mini / micro LED display devices, it is preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, and particularly preferably 60% or more, and may be 70% or more, 80% or more, or 90% or more, and more preferably around 99.9% because it has the best effect of reducing color cast. The upper limit of the haze value of the diffusion layer is not particularly limited, and may be 100%.

[0047] The total light transmittance of the diffusion layer of the present invention is not particularly limited, but is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more, from the viewpoint of ensuring the brightness of the mini / micro LED display device. The upper limit of the total light transmittance of the diffusion layer of the present invention is not particularly limited, but may be less than 100%, 99.9% or less, or 99% or less.

[0048] The haze value and total light transmittance of the diffusion layer of the present invention can be measured by the methods specified in JIS 7136 and JIS 7361, respectively, and can be controlled by the types and thicknesses of the resin layer and adhesive layer described below, the types and amounts of the light-diffusing fine particles and colorant described below, and the like.

[0049] From the viewpoint of more efficiently reducing color cast in mini / micro LED display devices, the thickness of the diffusion layer of the present invention is preferably 10 to 300 μm, more preferably 15 to 250 μm, even more preferably 20 to 300 μm, and still more preferably 25 to 200 μm.

[0050] The light-diffusing fine particles have an appropriate refractive index difference with the resin layer and impart diffusion properties to the diffusion layer. When the diffusion layer contains light-diffusing fine particles, light diffusion properties are imparted, which is preferable in terms of achieving a configuration in which H1 and H2 satisfy the relationship H1>H2. Examples of light-diffusing fine particles include inorganic fine particles and polymeric fine particles. Examples of materials for inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide. Examples of materials for polymeric fine particles include silicone resin, acrylic resin, methacrylic resin (e.g., polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin. The light-diffusing microparticles are preferably polymeric microparticles, and in particular, microparticles made of silicone resin (e.g., the Tospearl series manufactured by Momentive Performance Materials Japan, Inc.) have excellent dispersibility and stability in the resin layer, an appropriate refractive index difference from the resin layer, and provide a diffusion layer with excellent diffusion performance that exhibits uniform haze within the surface, making them suitable for reducing color cast in mini / micro LED display devices. The shape of the light-diffusing microparticles can be, for example, spherical, flat, or irregular. The light-diffusing microparticles may be used alone or in combination of two or more types.

[0051] The average particle diameter of the light-diffusing fine particles is preferably 0.1 μm or more, more preferably 0.15 μm or more, even more preferably 0.2 μm or more, and particularly preferably 0.25 μm or more, from the viewpoint of imparting appropriate light-diffusing performance to the diffusion layer. Furthermore, the average particle diameter of the light-diffusing fine particles is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image. The average particle diameter can be measured, for example, using a Coulter counter.

[0052] The refractive index of the light-diffusing fine particles is preferably 1.2 to 5, more preferably 1.25 to 4.5, and may be 1.3 to 4, or 1.35 to 3.

[0053] The absolute value of the refractive index difference between the light-diffusing particles and the resin layer constituting the diffusion layer (the resin layer in the diffusion layer excluding the light-diffusing particles) is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.03 or more, and may be 0.04 or more, or even 0.05 or more, from the viewpoint of more efficiently reducing color cast in mini / micro LED display devices. Furthermore, the absolute value of the refractive index difference between the light-diffusing particles and the resin layer is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image.

[0054] The content of the light-diffusing fine particles in the diffusion layer is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, even more preferably 0.1 parts by weight or more, and particularly preferably 0.15 parts by weight or more, relative to 100 parts by weight of the resin constituting the resin layer, from the viewpoint of imparting appropriate light-diffusing performance to the diffusion layer. Also, the content of the light-diffusing fine particles is preferably 80 parts by weight or less, more preferably 70 parts by weight or less, relative to 100 parts by weight of the resin constituting the resin layer, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image.

[0055] Examples of the resin layer constituting the diffusion layer include an ionizing radiation curable resin layer and an adhesive layer. When the resin layer is composed of an ionizing radiation curable resin layer, examples of the ionizing radiation include ultraviolet light, visible light, infrared light, and electron beams. Preferred is ultraviolet light, and therefore the diffusion layer is preferably composed of an ultraviolet curable resin layer. Examples of the ultraviolet curable resin include acrylic resins, aliphatic (e.g., polyolefin) resins, and urethane resins.

[0056] The diffusion layer of the present invention is preferably an adhesive layer. When the diffusion layer is composed of an adhesive layer, the diffusion layer and / or anti-reflection layer fills the steps of the optical semiconductor elements arranged on the substrate of the mini / micro LED display device without gaps, which is preferable in that it has excellent step absorption properties and can prevent display unevenness. Examples of the adhesive layer include an adhesive layer formed from an adhesive composition selected from a photocurable adhesive composition and a solvent-based adhesive composition. The adhesive layer is preferably an adhesive layer formed from a photocurable adhesive composition in that it has excellent step absorption properties and excellent processability.

[0057] The photocurable pressure-sensitive adhesive composition contains a polymer, a photopolymerizable compound, and a photopolymerization initiator. That is, the photocurable pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer contains a polymer, a photopolymerizable compound, and a photopolymerization initiator.

[0058] The adhesive layer formed using the photocurable adhesive composition is roughly divided into a type that undergoes photocuring (first form) and a type that does not undergo photocuring but undergoes photocuring after being attached to a display panel described below (second form).

[0059] [First form] The pressure-sensitive adhesive layer of the first type can be formed by applying a photocurable pressure-sensitive adhesive composition containing a polymer, a photopolymerizable compound, and a photopolymerization initiator onto a release film and then photocuring the composition.

[0060] (polymer) Examples of the base polymer contained in the photocurable pressure-sensitive adhesive composition include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy-based polymers, fluorine-based polymers, and rubber-based polymers such as natural rubber and synthetic rubber. In particular, acrylic polymers are preferably used because they exhibit adhesive properties such as moderate wettability, cohesiveness, and adhesiveness, are excellent in weather resistance and heat resistance, and have a wide variety of monomers, allowing for a wide range of design latitude.

[0061] The acrylic polymer contains a (meth)acrylic acid alkyl ester as a main constituent monomer component. In this specification, "(meth)acrylic" means acrylic and / or methacrylic. The amount of the (meth)acrylic acid alkyl ester relative to the total amount of the monomer components constituting the acrylic polymer is preferably 50% by weight or more, more preferably 55% by weight or more, and even more preferably 60% by weight or more.

[0062] As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group with a carbon number of 1 to 20 is preferably used. The (meth)acrylic acid alkyl ester may have a branched alkyl group or may have a cyclic alkyl group.

[0063] Specific examples of the (meth)acrylic acid alkyl ester having a chain alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, and isooctyl (meth)acrylate. Examples of the alkyl (meth)acrylate having a chain alkyl group that is preferred for use in the first embodiment include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octadecyl (meth)acrylate, and dodecyl (meth)acrylate. The amount of the (meth)acrylic acid alkyl ester having a chain alkyl group relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 40 to 90% by weight, and may be 45 to 80% by weight, or 50 to 70% by weight.

[0064] Specific examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; and (meth)acrylic acid esters having a tricyclic or higher aliphatic hydrocarbon ring such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate. Preferred (meth)acrylic acid alkyl esters having an alicyclic alkyl group used in the first embodiment are cyclohexyl (meth)acrylate and isobornyl (meth)acrylate. The amount of the (meth)acrylic acid alkyl ester having an alicyclic alkyl group relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 3 to 50% by weight, and may be 5 to 40% by weight or 10 to 30% by weight.

[0065] The acrylic polymer may contain a polar group-containing monomer such as a hydroxyl group-containing monomer, a carboxyl group-containing monomer, or a nitrogen-containing monomer as a constituent monomer component. When the acrylic polymer contains a polar group-containing monomer as a constituent monomer component, the cohesive strength of the pressure-sensitive adhesive tends to be increased, and the adhesive strength tends to be improved. Preferred polar group-containing monomers used in the first embodiment are hydroxyl group-containing monomers and nitrogen-containing monomers, and more preferably hydroxyl group-containing monomers. The amount of the polar group-containing monomer (the total of the hydroxyl group-containing monomer, the carboxyl group-containing monomer, and the nitrogen-containing monomer) relative to the total amount of the monomer components constituting the acrylic polymer is, for example, about 3 to 50 wt %, and may be 5 to 40 wt %, or 10 to 30 wt %.

[0066] Examples of hydroxyl group-containing monomers include (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl (meth)acrylate. When a crosslinked structure is introduced into the polymer using an isocyanate crosslinking agent, the hydroxyl group can serve as a reaction site (crosslinking site) with the isocyanate group. Preferred hydroxyl group-containing monomers used in the first embodiment are 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. The amount of the hydroxyl group-containing monomer relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 3 to 50% by weight, and may be 5 to 40% by weight, or 10 to 30% by weight.

[0067] Examples of the carboxy group-containing monomer include acrylic monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate, as well as itaconic acid, maleic acid, fumaric acid, and crotonic acid. When a crosslinked structure is introduced into the polymer using an epoxy crosslinking agent, the carboxy group can serve as a reaction point (crosslinking point) with the epoxy group. A preferred carboxy group-containing monomer used in the first embodiment is (meth)acrylic acid. The amount of the carboxy group-containing monomer relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 3 to 50% by weight, and may be 5 to 40% by weight, or 10 to 30% by weight.

[0068] Examples of nitrogen-containing monomers include vinyl monomers such as N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, (meth)acryloylmorpholine, N-vinylcarboxylic acid amides, N-vinylcaprolactam, and acrylamide, as well as cyano group-containing monomers such as acrylonitrile and methacrylonitrile. A preferred nitrogen-containing monomer used in the first embodiment is N-vinylpyrrolidone. The amount of the nitrogen-containing monomer relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 3 to 50% by weight, and may be 5 to 40% by weight, or 10 to 30% by weight.

[0069] The acrylic polymer may contain, as monomer components other than those mentioned above (sometimes referred to as "other monomers"), vinyl monomers such as acid anhydride group-containing monomers, caprolactone adducts of (meth)acrylic acid, sulfonic acid group-containing monomers, phosphate group-containing monomers, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene; epoxy group-containing monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, and substituted or unsubstituted aralkyl (meth)acrylates such as benzyl (meth)acrylate. The amount of other monomers relative to the total amount of monomer components constituting the acrylic polymer is, for example, about 3 to 50% by weight, and may be 5 to 40% by weight or 10 to 30% by weight.

[0070] The glass transition temperature (Tg) of the polymer contained in the photocurable pressure-sensitive adhesive composition is preferably 0°C or lower. The glass transition temperature of the polymer may be -5°C or lower, -10°C or lower, or -15°C or lower. The glass transition temperature of the polymer is the peak top temperature of the loss tangent (tanδ) measured by dynamic viscoelasticity measurement. When a crosslinked structure is introduced into the polymer, the glass transition temperature can be calculated based on the theoretical Tg from the polymer composition. The theoretical Tg is calculated using the following Fox's formula. 1 / Tg=Σ(W i / Tg i ) Tg: Glass transition temperature of the copolymer (unit: K) W i : weight fraction of monomer i in the copolymer (copolymerization ratio by weight) Tg i : Glass transition temperature of homopolymer of monomer i (unit: K)

[0071] The above-mentioned monomer components can be polymerized by various known methods to obtain a polymer. Although the polymerization method is not particularly limited, it is preferable to prepare the polymer by photopolymerization. Since photopolymerization can prepare a polymer without using a solvent, it is not necessary to dry and remove the solvent when forming the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer with a large thickness can be formed uniformly.

[0072] In preparing the pressure-sensitive adhesive layer of the first type, it is preferable to prepare a polymer (prepolymer) with a low degree of polymerization in which a portion of the monomer components remain unreacted. The composition (prepolymer-forming composition) used to prepare the prepolymer preferably contains a photopolymerization initiator in addition to the monomer. The photopolymerization initiator may be selected appropriately depending on the type of monomer. For example, a photoradical polymerization initiator is used for the polymerization of acrylic polymers. Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

[0073] During polymerization, a chain transfer agent, a polymerization inhibitor (polymerization retarder), etc. may be used for the purpose of molecular weight adjustment, etc. Examples of chain transfer agents include thiols such as α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol, and α-methylstyrene dimer, etc.

[0074] The polymerization rate of the prepolymer is not particularly limited, but is preferably 3 to 50% by weight, more preferably 5 to 40% by weight, from the viewpoint of achieving a viscosity suitable for application to a substrate. The polymerization rate of the prepolymer can be adjusted to a desired range by adjusting the type and amount of photopolymerization initiator used, and the irradiation intensity and irradiation time of actinic rays such as UV light. The polymerization rate of the prepolymer is the non-volatile content when heated at 130°C for 3 hours, and is calculated using the following formula. The polymerization rate (non-volatile content) of the pressure-sensitive adhesive layer is also measured using the same method. Conversion rate (%) = weight after heating / weight before heating x 100

[0075] As described above, the photocurable pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer contains a polymer, a photopolymerizable compound, and a photopolymerization initiator. For example, the photocurable pressure-sensitive adhesive composition can be obtained by adding the photopolymerizable compound and the photopolymerization initiator to a prepolymer. Instead of using a prepolymer, a low-molecular-weight polymer (oligomer) may be used, and the photopolymerizable compound and the photopolymerization initiator may be mixed with the low-molecular-weight polymer to prepare the photocurable pressure-sensitive adhesive composition.

[0076] (Photopolymerizable compound) The photopolymerizable compound contained in the photocurable pressure-sensitive adhesive composition has one or more photopolymerizable functional groups in one molecule. The photopolymerizable functional group may be radically polymerizable, cationic polymerizable, or anionic polymerizable, but a radically polymerizable functional group having an unsaturated double bond (ethylenically unsaturated group) is preferred because of its excellent reactivity.

[0077] The prepolymer contains a polymer and unreacted monomers, and the unreacted monomers retain photopolymerizability. Therefore, it is not necessary to add a photopolymerizable compound when preparing a photocurable pressure-sensitive adhesive composition. When a photopolymerizable compound is added to the prepolymer, the photopolymerizable compound may be the same as or different from the monomer used in preparing the prepolymer.

[0078] When the polymer is an acrylic polymer, the compound added as the photopolymerizable compound is preferably a monomer or oligomer having a (meth)acryloyl group as a photopolymerizable functional group, since this has high compatibility with the polymer. The photopolymerizable compound may be a polyfunctional compound having two or more photopolymerizable functional groups in one molecule. Examples of the photopolymerizable polyfunctional compound include polyfunctional (meth)acrylates. Examples of polyfunctional (meth)acrylates include bifunctional di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, bisphenol A ethylene oxide modified di(meth)acrylate, bisphenol A propylene oxide modified di(meth)acrylate, alkanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, pentaerythritol di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin di(meth)acrylate, and urethane di(meth)acrylate. trifunctional (meth)acrylic acid esters such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; tetrafunctional (meth)acrylic acid esters such as ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; and pentafunctional or higher (meth)acrylic acid esters such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate.

[0079] When a polyfunctional compound is used as the photopolymerizable compound, the amount of the polyfunctional compound used is preferably 10 parts by weight or less, more preferably 0.001 to 1 part by weight, and even more preferably 0.005 to 0.5 parts by weight, per 100 parts by weight of the polymer (including prepolymer). If the amount of the polyfunctional monomer used is excessively large, the adhesive layer after photocuring may have low viscosity and poor adhesive strength. The amount of the polyfunctional compound used may be 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 1 part by weight or less. The amount of the polyfunctional monomer used may be 0, 0.001 parts by weight or more, 0.01 parts by weight or more, or 0.1 parts by weight or more.

[0080] When a monomer that forms a prepolymer is used as the photopolymerizable compound, a hydroxyl group-containing monomer is preferred, with 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate being more preferred. When a hydroxyl group-containing monomer is used as the photopolymerizable compound, the amount of the hydroxyl group-containing monomer used is preferably 40 parts by weight or less, more preferably 1 to 30 parts by weight, and even more preferably 5 to 20 parts by weight, per 100 parts by weight of the polymer (including the prepolymer). The amount of the hydroxyl group-containing monomer used may be 40 parts by weight or less, 30 parts by weight or less, or 20 parts by weight or less. The amount of the hydroxyl group-containing monomer used may be 0, 1 part by weight or more, 5 parts by weight or more, or 10 parts by weight or more.

[0081] (Photopolymerization initiator) The photocurable pressure-sensitive adhesive composition contains a photopolymerization initiator. The photopolymerization initiator generates radicals, acids, bases, etc. when irradiated with actinic rays such as ultraviolet rays, and can be appropriately selected depending on the type of photopolymerizable compound, etc. When the photopolymerizable compound is a compound having a (meth)acryloyl group (for example, a monofunctional or polyfunctional (meth)acrylate), it is preferable to use a photoradical polymerization initiator as the photopolymerization initiator. The photopolymerization initiator may be used alone or in combination of two or more types.

[0082] If the photopolymerization initiator used in preparing (polymerizing) the polymer (including prepolymer) remains without being deactivated, the addition of the photopolymerization initiator may be omitted. When a photopolymerization initiator is added to the polymer, the photopolymerization initiator to be added may be the same as or different from the photopolymerization initiator used in preparing the polymer.

[0083] The content of the photopolymerization initiator in the photocurable pressure-sensitive adhesive composition is about 0.01 to 10 parts by weight, preferably about 0.05 to 5 parts by weight, relative to 100 parts by weight of the total amount of monomers (monomers used to prepare the polymer and photopolymerizable compounds added to the polymer).

[0084] (Silane coupling agent) The photocurable pressure-sensitive adhesive composition may contain a silane coupling agent within a range that does not impair the effects of the present invention. When the photocurable pressure-sensitive adhesive composition contains a silane coupling agent, the adhesive reliability to glass (particularly, the adhesive reliability to glass under high-temperature and high-humidity environments) is improved, which is preferable.

[0085] The silane coupling agent is not particularly limited, but preferred examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane. Of these, γ-glycidoxypropyltrimethoxysilane is preferred. An example of a commercially available product is "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). The silane coupling agents may be used alone or in combination of two or more.

[0086] The content of the silane coupling agent in the photocurable pressure-sensitive adhesive composition is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.03 to 0.5 parts by weight, per 100 parts by weight of the polymer.

[0087] (Other ingredients) In the first embodiment, the photocurable pressure-sensitive adhesive composition may contain components other than the polymer, photopolymerizable compound, and photopolymerization initiator. For example, a chain transfer agent may be contained for the purpose of adjusting the photocuring rate, etc. Furthermore, an oligomer or a tackifier may be contained for the purpose of adjusting the viscosity of the photocurable pressure-sensitive adhesive composition or the adhesive strength of the pressure-sensitive adhesive layer, etc. As the oligomer, for example, one having a weight-average molecular weight of about 1,000 to 30,000 is used. As the oligomer, an acrylic oligomer is preferred because of its excellent compatibility with acrylic polymers. The photocurable pressure-sensitive adhesive composition may contain additives such as a plasticizer, a softener, an antidegradant, a filler, an antioxidant, a surfactant, an antistatic agent, and a colorant.

[0088] [Second form] The pressure-sensitive adhesive layer of the second type is a pressure-sensitive adhesive layer of a type that does not undergo photocuring, and is formed by forming a photocurable pressure-sensitive adhesive composition into a sheet shape. The pressure-sensitive adhesive layer of the second type contains a photopolymerizable compound in an unreacted state, and therefore the pressure-sensitive adhesive layer has photocurability.

[0089] The photocurable pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer of the second type contains a polymer, a photopolymerizable compound, and a photopolymerization initiator.

[0090] (polymer) As in the first embodiment, various polymers can be used as the polymer contained in the pressure-sensitive adhesive composition, and an acrylic polymer is preferably used. The monomer components constituting the acrylic polymer are the same as in the first embodiment.

[0091] In order to introduce a crosslinked structure using a crosslinking agent described below, the monomer components constituting the polymer preferably contain a hydroxyl group-containing monomer and / or a carboxyl group-containing monomer. For example, when an isocyanate-based crosslinking agent is used, it is preferable to contain a hydroxyl group-containing monomer as a monomer component. When an epoxy-based crosslinking agent is used, it is preferable to contain a carboxyl group-containing monomer as a monomer.

[0092] In the second embodiment, since photocuring is not performed on the substrate, a polymer having a relatively large molecular weight is used as the photocurable adhesive composition to form a solid (regular) adhesive layer. The weight-average molecular weight of the polymer is, for example, about 100,000 to 2,000,000.

[0093] Since the high-molecular-weight polymer is solid, the PSA composition is preferably a solution in which the polymer is dissolved in an organic solvent. For example, the polymer solution can be obtained by solution polymerization of the monomer components. The polymer solution may also be prepared by dissolving a solid polymer in an organic solvent.

[0094] Ethyl acetate, toluene, etc. are generally used as solvents for solution polymerization. The solution concentration is usually about 20 to 80% by weight. As the polymerization initiator, thermal polymerization initiators such as azo initiators, peroxide initiators, and redox initiators that combine peroxides and reducing agents (e.g., a combination of persulfate and sodium hydrogen sulfite, or a combination of peroxide and sodium ascorbate) are preferably used. The amount of polymerization initiator used is not particularly limited, but is preferably about 0.005 to 5 parts by weight, and more preferably about 0.02 to 3 parts by weight, per 100 parts by weight of the total amount of monomer components that form the polymer.

[0095] (Photopolymerizable compound) In the second embodiment, the photopolymerizable compound contained in the pressure-sensitive adhesive composition is the same as that described above for the first embodiment, and a compound having one or more photopolymerizable functional groups is used.

[0096] (Photopolymerization initiator) The photopolymerization initiator contained in the pressure-sensitive adhesive composition in the second embodiment is the same as that described above for the first embodiment, and preferably has an absorption maximum in the wavelength region of 330 to 400 nm. The amount of the photopolymerization initiator is about 0.01 to 10 parts by weight, preferably about 0.05 to 5 parts by weight, per 100 parts by weight of the polymer.

[0097] (Crosslinking agent) The pressure-sensitive adhesive composition of the second embodiment preferably contains a crosslinking agent capable of crosslinking with the polymer. Specific examples of crosslinking agents for introducing a crosslinked structure into the polymer include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred because they have high reactivity with the hydroxyl groups and carboxyl groups of the polymer and facilitate the introduction of a crosslinked structure. These crosslinking agents react with functional groups such as hydroxyl groups and carboxyl groups introduced into the polymer to form a crosslinked structure.

[0098] The isocyanate crosslinking agent is a polyisocyanate having two or more isocyanate groups in one molecule. Examples of the isocyanate crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; trimethylolpropane / Examples of such isocyanate adducts include tolylene diisocyanate trimer adducts (e.g., "Coronate L" manufactured by Tosoh), trimethylolpropane / hexamethylene diisocyanate trimer adducts (e.g., "Coronate HL" manufactured by Tosoh), trimethylolpropane adducts of xylylene diisocyanate (e.g., "Takenate D110N" manufactured by Mitsui Chemicals), and isocyanurate of hexamethylene diisocyanate (e.g., "Coronate HX" manufactured by Tosoh).

[0099] The epoxy crosslinking agent is a polyfunctional epoxy compound having two or more epoxy groups in one molecule, and the epoxy group of the epoxy crosslinking agent may be a glycidyl group. Examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. As the epoxy-based crosslinking agent, commercially available products such as "Denacol" manufactured by Nagase ChemteX, and "Tetrad X" and "Tetrad C" manufactured by Mitsubishi Gas Chemical may be used.

[0100] The amount of crosslinking agent is about 0.01 to 5 parts by weight relative to 100 parts by weight of the polymer, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.2 parts by weight or more, or may be 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less.

[0101] (Other ingredients) The PSA composition of the second embodiment may contain, in addition to the above components, an oligomer, a tackifier, a silane coupling agent, a chain transfer agent, a plasticizer, a softener, an antidegradant, a filler, an antioxidant, a surfactant, an antistatic agent, a colorant, etc.

[0102] The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer (third form) formed from a solvent-based pressure-sensitive adhesive composition. The solvent-based pressure-sensitive adhesive composition contains at least a polymer and a solvent, and may also contain a crosslinking agent. That is, the solvent-based pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer of the third form contains a polymer and a solvent, and may also contain a crosslinking agent as needed.

[0103] [Third form] The pressure-sensitive adhesive layer of the third embodiment can be formed by applying a solvent-based pressure-sensitive adhesive composition containing a polymer and a solvent, and optionally a crosslinking agent, onto a release film, and then drying and removing the solvent.

[0104] The solvent-based pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer of the third embodiment contains a polymer and a solvent, and optionally a crosslinking agent.

[0105] (polymer) As in the first embodiment, various polymers can be used as the polymer contained in the solvent-based pressure-sensitive adhesive composition, and an acrylic polymer is preferably used. The monomer components constituting the acrylic polymer are the same as in the first embodiment.

[0106] In the third embodiment, in order to form a solid (regular) pressure-sensitive adhesive layer on a substrate, a polymer having a relatively large molecular weight is used as the polymer contained in the solvent-based pressure-sensitive adhesive composition. The weight-average molecular weight of the polymer is, for example, about 100,000 to 2,000,000.

[0107] (solvent) Since the polymer in the third form is solid, the solvent-based PSA composition is a solution in which the polymer is dissolved in an organic solvent. For example, the polymer solution can be obtained by solution polymerization of the monomer components. The polymer solution may also be prepared by dissolving a solid polymer in an organic solvent.

[0108] The solvent generally used is ethyl acetate, toluene, etc. The solution concentration is usually about 20 to 80% by weight.

[0109] When the monomer components are solution-polymerized, the polymerization initiator preferably used is a thermal polymerization initiator such as an azo initiator, a peroxide initiator, or a redox initiator that combines a peroxide with a reducing agent (for example, a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate). The amount of the polymerization initiator used is not particularly limited, but is preferably about 0.005 to 5 parts by weight, and more preferably about 0.02 to 3 parts by weight, per 100 parts by weight of the total amount of the monomer components that form the polymer.

[0110] (Crosslinking agent) The solvent-based PSA composition of the third embodiment may contain a crosslinking agent capable of crosslinking with the above-mentioned polymer. When the solvent-based PSA composition contains a (meth)acrylic block copolymer, the PSA layer of the third embodiment has sufficient shape stability and therefore does not need to contain a crosslinking agent.

[0111] In the third embodiment, when the solvent-based pressure-sensitive adhesive composition contains a crosslinking agent, the crosslinking agent is the same as that described above for the second embodiment, and isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred.

[0112] In the third embodiment, when the solvent-based pressure-sensitive adhesive composition contains a crosslinking agent, the content thereof is about 0.01 to 5 parts by weight, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.2 parts by weight or more, or may be 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less, relative to 100 parts by weight of the polymer.

[0113] (Other ingredients) The solvent-based PSA composition of the third embodiment may contain, in addition to the above components, an oligomer, a tackifier, a silane coupling agent, a chain transfer agent, a plasticizer, a softener, an antidegradant, a filler, an antioxidant, a surfactant, an antistatic agent, a colorant, etc.

[0114] <Anti-reflection layer> The anti-reflection layer of the present invention is a layer having a function of preventing reflection of light, specifically, a function of preventing reflection of metal wiring in a mini / micro LED display device, and is preferably composed of a resin layer. The anti-reflection layer of the present invention is not limited as long as it has a function of preventing reflection of light, but preferably contains a colorant dispersed or dissolved in the resin layer.

[0115] The haze value of the antireflection layer of the present invention is not particularly limited, but from the viewpoint of ensuring the visibility of the mini / micro LED display device, it is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, and particularly preferably 15% or less. Furthermore, from the viewpoint of efficiently reducing color cast in the mini / micro LED display device, the haze value of the antireflection layer of the present invention is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, particularly preferably 8% or more, and may even be 10% or more.

[0116] The total light transmittance of the anti-reflection layer of the present invention is not particularly limited, but from the viewpoint of further improving the anti-reflection function and contrast of metal wiring and the like in mini / micro LED display devices, it is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, and particularly preferably 10% or less. Furthermore, from the viewpoint of ensuring the brightness of the mini / micro LED display device, the total light transmittance of the anti-reflection layer of the present invention is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, particularly preferably 2% or more, and may even be 2.5% or more, or 3% or more.

[0117] The haze value and total light transmittance of the antireflection layer of the present invention can be measured by the methods specified in JIS 7136 and JIS 7361, respectively, and can be controlled by the types and thicknesses of the resin layer and pressure-sensitive adhesive layer described below, the light-diffusing fine particles described above, and the types and blending amounts of the colorant described below.

[0118] The thickness of the antireflection layer of the present invention is preferably 10 to 300 μm, more preferably 15 to 250 μm, more preferably 20 to 200 μm, even more preferably 25 to 150 μm, or even more preferably 30 to 100 μm, from the viewpoint of further improving the antireflection function of metal wiring and the like in mini / micro LED display devices and contrast.

[0119] Examples of resin layers constituting the antireflection layer include an ionizing radiation curable resin layer and an adhesive layer. The ionizing radiation curable resin layer and adhesive layer may be the same as those constituting the diffusion layer described above. The antireflection layer is preferably composed of an adhesive layer, since the diffusion layer and / or antireflection layer fills the steps of the optical semiconductor elements arranged on the substrate of the mini / micro LED display device without gaps, providing excellent step absorption and preventing display unevenness.

[0120] The diffusion layer and the anti-reflection layer are preferably both pressure-sensitive adhesive layers, since the diffusion layer and / or the anti-reflection layer are tightly packed into the steps of the optical semiconductor elements arranged on the substrate of the mini / micro LED display device, have excellent step absorption properties, and can prevent display unevenness. The anti-reflection layer may be composed of the same resin layer as the diffusion layer, or may be composed of a different resin layer.

[0121] The colorant imparts light-blocking properties to the anti-reflection layer, imparting anti-reflection capabilities. When the anti-reflection layer contains a colorant, its light transmittance decreases, which is preferable for achieving a configuration in which the T1 and T2 satisfy the relationship T1>T2. The anti-reflection layer seals the gap between the metal wiring layer and the LED chip of a self-luminous display device (mini / micro LED display device), thereby preventing reflections from the metal wiring and preventing color mixing between the LED chips and improving image contrast.

[0122] The colorant may be a dye or a pigment as long as it is soluble or dispersible in the antireflection layer. Dyes are preferred because they can achieve low haze even with a small amount added, do not settle like pigments, and are easily distributed uniformly. Pigments are also preferred because they provide high color development even with a small amount added. When using a pigment as a colorant, it is preferable that it has low or no conductivity.

[0123] The colorant is not particularly limited, but is preferably one that absorbs visible light and is transparent to ultraviolet light. That is, the colorant preferably has an average transmittance at wavelengths of 330 to 400 nm that is greater than the average transmittance at wavelengths of 400 to 700 nm. Furthermore, the colorant preferably has a maximum transmittance at wavelengths of 330 to 400 nm that is greater than the maximum transmittance at wavelengths of 400 to 700 nm. The transmittance of the colorant is measured using a solution or dispersion diluted with an appropriate solvent or dispersion medium (an organic solvent with low absorption in the wavelength range of 330 to 700 nm) such as tetrahydrofuran (THF) so that the transmittance at a wavelength of 400 nm is approximately 50 to 60%.

[0124] Examples of UV-transmitting black pigments that absorb less UV light than visible light include "9050BLACK" and "UVBK-0001" manufactured by Tokushiki. Examples of UV-transmitting black dyes include "SOC-L-0123" manufactured by Orient Chemical Industries.

[0125] Carbon black and titanium black, which are commonly used as black colorants, have a higher UV absorption rate than visible light absorption rate (lower UV transmittance than visible light transmittance). Therefore, when a colorant such as carbon black is added to a photocurable adhesive composition that is sensitive to UV, much of the UV irradiated for photocuring is absorbed by the colorant, the amount of light absorbed by the photopolymerization initiator is small, and photocuring takes time (the cumulative amount of light irradiation increases). Furthermore, when the adhesive layer is thick, less UV reaches the surface opposite the light-irradiated surface, so photocuring tends to be insufficient even with long-term light irradiation. In contrast, by using a colorant with a higher UV transmittance than visible light, curing inhibition caused by the colorant can be suppressed.

[0126] From the viewpoint of imparting an appropriate antireflection ability to the antireflection layer, the content of the colorant in the antireflection layer is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and even more preferably 1 to 10 parts by weight, relative to 100 parts by weight of the resin constituting the resin layer, and may be appropriately set depending on the type of colorant, the color tone and light transmittance of the pressure-sensitive adhesive layer, etc. The colorant may be added to the composition as a solution or dispersion dissolved or dispersed in an appropriate solvent.

[0127] <Base material> The substrate that the optical semiconductor element encapsulation sheet of the present invention may have as another layer is not particularly limited, and examples thereof include glass and transparent plastic film substrates. The transparent plastic film substrate is not particularly limited, but is preferably one that has excellent visible light transmittance and excellent transparency (preferably one with a haze value of 5% or less), such as the transparent plastic film substrate described in JP 2008-90263 A. The transparent plastic film substrate is preferably one with low optical birefringence. The substrate can also be used, for example, as a cover member for a self-luminous display device. In this case, the transparent plastic film substrate is preferably a film formed from triacetyl cellulose (TAC), polycarbonate, acrylic polymer, polyolefin having a cyclic or norbornene structure, or the like. This configuration eliminates the need for a separate step of laminating a cover member during the production of the self-luminous display device, thereby reducing the number of steps and required components and improving production efficiency. Furthermore, this configuration allows the cover member to be made thinner. When the base material is a cover member, it becomes the outermost surface of the self-luminous display device.

[0128] The total light transmittance of the substrate is not particularly limited, but may be, for example, 85 to 100%, and may be 88% or more, 90% or more, or 92% or more.

[0129] The thickness of the substrate is not particularly limited, but is preferably in the range of 10 to 500 μm, more preferably in the range of 20 to 300 μm, and optimally in the range of 30 to 200 μm, taking into consideration, for example, strength, workability such as handleability, and thin layer property. The refractive index of the substrate is not particularly limited, but is, for example, in the range of 1.30 to 1.80, and preferably in the range of 1.40 to 1.70.

[0130] The substrate is preferably subjected to a reflective surface treatment and / or an anti-glare treatment. When the substrate is subjected to a reflective surface treatment and / or an anti-glare treatment, it becomes the outermost surface of the self-luminous display device, and can prevent a decrease in visibility due to reflection of external light or glare of images, or can adjust the appearance such as glossiness. An anti-glare treatment is preferred because it is easy to manufacture and low cost.

[0131] As the antireflection treatment, any known antireflection treatment can be used without any particular limitation, and examples thereof include antireflection (AR) treatment.

[0132] The anti-reflection (AR) treatment can be any known AR treatment without particular limitations. Specifically, it can be performed by forming an optical thin film with strictly controlled thickness and refractive index on a substrate, or an anti-reflection layer (AR layer) consisting of two or more layers of the optical thin film. The AR layer exhibits anti-reflection function by utilizing the optical interference effect to cancel out the reversed phases of incident light and reflected light. The wavelength range of visible light that exhibits anti-reflection function is, for example, 380 to 780 nm, with the wavelength range of 450 to 650 nm having particularly high luminosity. It is preferable to design the AR layer so as to minimize the reflectance at the center wavelength of 550 nm.

[0133] The AR layer is generally a multilayer antireflection layer having a structure in which two to five optical thin layers (thin films with strictly controlled thickness and refractive index) are laminated. By forming multiple layers of components with different refractive indexes to a predetermined thickness, the degree of freedom in the optical design of the AR layer is increased, the antireflection effect can be further improved, and the spectral reflectance characteristics can be made uniform (flat) in the visible light range. Since high thickness accuracy is required for the optical thin films, each layer is generally formed by a dry method such as vacuum deposition, sputtering, or CVD.

[0134] The anti-glare (AG) treatment can be any known AG treatment without any particular limitations, and can be performed, for example, by forming an anti-glare layer on a substrate. The anti-glare layer can be any known treatment without any limitations, and is generally formed as a layer in which inorganic or organic particles are dispersed as an anti-glare agent in a resin.

[0135] In this embodiment, the anti-glare layer is formed using an anti-glare layer-forming material containing a resin, particles, and a thixotropy-imparting agent, and convex portions are formed on the surface of the anti-glare layer by aggregation of the particles and the thixotropy-imparting agent. With this configuration, the anti-glare layer has excellent display characteristics that combine anti-glare properties with prevention of white blur. Furthermore, even though the anti-glare layer is formed using particle aggregation, the occurrence of protrusions on the surface of the anti-glare layer, which can cause appearance defects, can be prevented, thereby improving product yield.

[0136] Examples of the resin include a thermosetting resin and an ionizing radiation curable resin that is cured by ultraviolet light or light. As the resin, commercially available thermosetting resins and ultraviolet curable resins can also be used.

[0137] Examples of the thermosetting resin or ultraviolet-curable resin that can be used include curable compounds having at least one of an acrylate group and a methacrylate group that are cured by heat, light (ultraviolet light, etc.), electron beams, etc. Examples include oligomers or prepolymers of acrylates or methacrylates of polyfunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and polyhydric alcohols. These may be used alone or in combination of two or more.

[0138] The resin may also include a reactive diluent having at least one of an acrylate group and a methacrylate group. Examples of the reactive diluent include those described in JP 2008-88309 A, including monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, and polyfunctional methacrylates. Trifunctional or higher functional acrylates and trifunctional or higher functional methacrylates are preferred as the reactive diluent. This is because they can improve the hardness of the anti-glare layer. Examples of the reactive diluent include butanediol glycerin ether diacrylate, acrylate of isocyanuric acid, and methacrylate of isocyanuric acid. These may be used alone or in combination.

[0139] The primary function of the particles forming the anti-glare layer is to provide the surface of the anti-glare layer with an irregular shape, imparting anti-glare properties, and to control the haze value of the anti-glare layer. The haze value of the anti-glare layer can be designed by controlling the difference in refractive index between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited, and examples include silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, and calcium sulfate particles. The organic particles are not particularly limited, and examples include polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyethylene fluoride resin powder. These inorganic particles and organic particles may be used alone or in combination of two or more kinds.

[0140] The weight-average particle size (D) of the particles is preferably in the range of 2.5 to 10 μm. By setting the weight-average particle size of the particles in this range, for example, it is possible to achieve better anti-glare properties and prevent white blur. The weight-average particle size of the particles is more preferably in the range of 3 to 7 μm. The weight-average particle size of the particles can be measured, for example, by the Coulter counting method. For example, a particle size distribution measuring device using the pore electrical resistance method (product name: Coulter Multisizer, manufactured by Beckman Coulter) is used to measure the electrical resistance of an electrolyte solution equivalent to the volume of particles when the particles pass through the pores, thereby measuring the number and volume of the particles and calculating the weight-average particle size.

[0141] The shape of the particles is not particularly limited, and may be, for example, roughly spherical like beads, or irregularly shaped like powder, but roughly spherical particles are preferred, more preferably roughly spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0142] The ratio of the particles in the anti-glare layer is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, and even more preferably in the range of 1 to 7 parts by weight, relative to 100 parts by weight of the resin. By setting the ratio in this range, for example, the anti-glare property can be improved and white blur can be prevented.

[0143] Examples of thixotropy-imparting agents for forming the anti-glare layer include organic clay, oxidized polyolefin, and modified urea.

[0144] The organoclay is preferably an organo-treated clay to improve its affinity with the resin. Examples of the organoclay include layered organoclay. The organoclay may be prepared in-house or may be a commercially available product. Examples of the commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasif ME-100, Somasif MAE, Somasif MTE, Somasif MEE, and Somasif MPE (trade names, all manufactured by Co-op Chemical Co., Ltd.); Esben, Esben C, Esben E, Esben W, Esben P, Esben WX, Esben N-400, Esben NX, Esben NX80, Esben NO12S, Esben NEZ, Esben NO12, Esben NE, Esben NZ, Esben NZ70, Organite, Organite D, and Organite T (trade names, all manufactured by Hojun Co., Ltd.); Kunipia F, Kunipia G, and Kunipia G4 (trade names, all manufactured by Kunimine Industries Co., Ltd.); and Thixogel VZ, Clayton HT, and Clayton 40 (trade names, all manufactured by Rockwood Additives).

[0145] The oxidized polyolefin may be prepared in-house or may be a commercially available product, such as Disparlon 4200-20 (trade name, manufactured by Kusumoto Chemical Co., Ltd.) or Flownon SA300 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.).

[0146] The modified urea is a reaction product of an isocyanate monomer or its adduct with an organic amine. The modified urea may be prepared in-house or may be a commercially available product. Examples of the commercially available product include BYK410 (manufactured by BYK-Chemie).

[0147] The thixotropy-imparting agents may be used alone or in combination of two or more.

[0148] In this embodiment, the height of the convex ridge portions from the roughness mean line of the anti-glare layer is preferably less than 0.4 times the thickness of the anti-glare layer. More preferably, it is in the range of 0.01 times or more but less than 0.4 times, and even more preferably, it is in the range of 0.01 times or more but less than 0.3 times. This range can suitably prevent the formation of protrusions on the convex ridge portions that could cause appearance defects. By having convex ridge portions of this height, the anti-glare layer of this embodiment can be made less likely to cause appearance defects. Here, the height from the mean line can be measured, for example, by the method described in JP 2017-138620 A.

[0149] The proportion of the thixotropy-imparting agent in the anti-glare layer is preferably in the range of 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, relative to 100 parts by weight of the resin.

[0150] The thickness (d) of the anti-glare layer is not particularly limited, but is preferably in the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer within this range, for example, it is possible to prevent curling of the optical semiconductor element encapsulation sheet, and to avoid problems such as poor transportability and reduced productivity. Furthermore, when the thickness (d) is within this range, the weight-average particle size (D) of the particles is preferably in the range of 2.5 to 10 μm, as described above. The combination of the thickness (d) of the anti-glare layer and the weight-average particle size (D) of the particles described above can further enhance anti-glare properties. The thickness (d) of the anti-glare layer is more preferably in the range of 3 to 8 μm.

[0151] The relationship between the thickness (d) of the anti-glare layer and the weight average particle size (D) of the particles is preferably within the range of 0.3≦D / d≦0.9. This relationship makes it possible to provide an anti-glare layer with better anti-glare properties, preventing white blur, and eliminating appearance defects.

[0152] In the optical semiconductor element encapsulation sheet of the present invention, as described above, the anti-glare layer forms convex portions on the surface of the anti-glare layer by aggregation of the particles and the thixotropy-imparting agent. In the aggregation portions forming the convex portions, the particles are present in a state of being gathered in multiple groups in the surface direction of the anti-glare layer. This gives the convex portions a smooth shape. By having convex portions of such a shape, the anti-glare layer of this embodiment can maintain anti-glare properties, prevent white blur, and further reduce the occurrence of appearance defects.

[0153] The surface shape of the anti-glare layer can be designed as desired by controlling the aggregation state of the particles contained in the anti-glare layer-forming material. The aggregation state of the particles can be controlled, for example, by the material of the particles (e.g., the chemical modification state of the particle surface, affinity for solvents or resins, etc.), the type and combination of resins (binders) or solvents, etc. In this embodiment, the aggregation state of the particles can be controlled by a thixotropy-imparting agent contained in the anti-glare layer-forming material. As a result, the aggregation state of the particles can be controlled as described above, and the convex portions can have a smooth shape.

[0154] In the optical semiconductor element encapsulation sheet of this embodiment, when the substrate is formed from a resin or the like, it is preferable that a permeation layer be present at the interface between the substrate and the anti-glare layer. The permeation layer is formed by the resin component contained in the material forming the anti-glare layer permeating into the substrate. The formation of the permeation layer is preferable because it can improve the adhesion between the substrate and the anti-glare layer. The permeation layer preferably has a thickness in the range of 0.2 to 3 μm, more preferably 0.5 to 2 μm. For example, when the substrate is triacetyl cellulose and the resin contained in the anti-glare layer is an acrylic resin, the permeation layer can be formed. The permeation layer can be confirmed, and its thickness can be measured, by observing the cross section of the optical semiconductor element encapsulation sheet with a transmission electron microscope (TEM), for example.

[0155] In the present embodiment, even when the sheet for encapsulating an optical semiconductor element having such a permeation layer is applied, a desired smooth surface unevenness that achieves both anti-glare properties and prevention of white blur can be easily formed. The permeation layer is preferably formed thicker for a substrate that has poorer adhesion to the anti-glare layer in order to improve adhesion.

[0156] In this embodiment, in the anti-glare layer, appearance defects having a maximum diameter of 200 μm or more are formed within 1 m of the anti-glare layer. 2 It is preferable that there is one or less defect per unit area. It is more preferable that there is no such defect in appearance.

[0157] In this embodiment, the substrate on which the anti-glare layer is formed preferably has a haze value in the range of 0 to 10%. The haze value is a haze value (cloudiness) according to JIS K 7136 (2000 edition). The haze value is more preferably in the range of 0 to 5%, and even more preferably in the range of 0 to 3%. In order to achieve a haze value in the above range, it is preferable to select the particles and the resin so that the difference in refractive index between the particles and the resin is in the range of 0.001 to 0.02. A haze value in the above range allows for a clear image to be obtained and improves contrast in dark places.

[0158] In this embodiment, the average tilt angle θa (°) of the uneven shape on the surface of the anti-glare layer is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5, even more preferably in the range of 1.0 to 4.0, and particularly preferably in the range of 1.6 to 4.0. Here, the average tilt angle θa is a value defined by the following mathematical formula (1). The average tilt angle θa is a value measured, for example, by the method described in JP 2017-138620 A. Average inclination angle θa=tan-1Δa (1)

[0159] In the above formula (1), Δa is the value obtained by dividing the sum (h1 + h2 + h3··· + hn) of the differences (heights h) between the peaks of adjacent peaks and the lowest points of adjacent valleys in the reference length L of a roughness curve defined in JIS B 0601 (1994 edition) by the reference length L, as shown in the following formula (2). The roughness curve is a curve obtained by removing surface waviness components longer than a predetermined wavelength from a profile curve using a phase difference compensation high-pass filter. The profile curve is the outline that appears at the cut surface when the target surface is cut by a plane perpendicular to the target surface. Δa=(h1+h2+h3+hn) / L (2)

[0160] When θa is in the above range, the anti-glare property is more excellent and white blur can be prevented.

[0161] When forming an anti-glare layer, it is preferable that the prepared anti-glare layer-forming material (coating liquid) exhibits thixotropy, and the Ti value, as defined below, is preferably in the range of 1.3 to 3.5, and more preferably in the range of 1.3 to 2.8. Ti value = β1 / β2 Here, β1 is the viscosity measured using a HAAKE RheoStress 6000 at a shear rate of 20 (1 / s), and β2 is the viscosity measured using a HAAKE RheoStress 6000 at a shear rate of 200 (1 / s).

[0162] If the Ti value is less than 1.3, defects in appearance are likely to occur, and anti-glare properties and white blur properties are deteriorated. If the Ti value is more than 3.5, the particles are less likely to aggregate and are more likely to be dispersed.

[0163] The anti-glare layer of this embodiment can be produced by any method, for example, by preparing an anti-glare layer-forming material (coating liquid) containing the resin, the particles, the thixotropy-imparting agent, and a solvent, applying the anti-glare layer-forming material (coating liquid) to the substrate to form a coating film, and curing the coating film to form the anti-glare layer. In this embodiment, a method of imparting a concave-convex shape by a transfer method using a mold, or an appropriate method such as sandblasting or an embossing roll can also be used.

[0164] The solvent is not particularly limited, and various solvents can be used. One type may be used alone, or two or more types may be used in combination. The optimal solvent type and solvent ratio depend on the composition of the resin, the type and content of the particles and the thixotropy-imparting agent, etc. The solvent is not particularly limited, but examples include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0165] When the permeation layer is formed using triacetyl cellulose (TAC) as the base material, a good solvent for TAC can be suitably used, such as ethyl acetate, methyl ethyl ketone, or cyclopentanone.

[0166] In addition, by appropriately selecting the solvent, the thixotropy of the anti-glare layer forming material (coating liquid) can be well expressed by the thixotropy imparting agent.For example, when using organic clay, toluene and xylene can be preferably used alone or in combination; for example, when using oxidized polyolefin, methyl ethyl ketone, ethyl acetate, propylene glycol monomethyl ether can be preferably used alone or in combination; for example, when using modified urea, butyl acetate and methyl isobutyl ketone can be preferably used alone or in combination.

[0167] Various leveling agents can be added to the anti-glare layer-forming material. For example, fluorine-based or silicone-based leveling agents can be used as the leveling agent to prevent coating unevenness (uniformity of the coated surface). In this embodiment, an appropriate leveling agent can be selected depending on the case where antifouling properties are required on the surface of the anti-glare layer, or where an anti-reflection layer (low refractive index layer) or a layer containing an interlayer filler is formed on the anti-glare layer. In this embodiment, for example, the inclusion of the thixotropy-imparting agent can impart thixotropy to the coating liquid, thereby making coating unevenness less likely to occur. Therefore, this embodiment has the advantage of being able to broaden the options for the leveling agent.

[0168] The amount of the leveling agent to be added is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight, relative to 100 parts by weight of the resin.

[0169] The anti-glare layer-forming material may optionally contain pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antifouling agents, antioxidants, etc., within the range that does not impair performance. These additives may be used alone or in combination of two or more.

[0170] The anti-glare layer forming material may be a conventionally known photopolymerization initiator such as that described in JP-A-2008-88309.

[0171] Examples of methods that can be used to coat the anti-glare layer-forming material on the substrate include fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating.

[0172] The anti-glare layer-forming material is applied to a substrate to form a coating film, and the coating film is cured. Prior to the curing, the coating film is preferably dried. The drying may be, for example, natural drying, air drying by blowing air, heat drying, or a combination of these methods.

[0173] The method for curing the coating film of the anti-glare layer-forming material is not particularly limited, but ultraviolet curing is preferred. The irradiation dose of the energy ray source is 50 to 500 mJ / cm as the cumulative exposure dose at an ultraviolet wavelength of 365 nm. 2 The irradiation dose is preferably 50 mJ / cm 2 If the curing rate is 500 mJ / cm or more, the curing is more sufficient, and the hardness of the formed anti-glare layer is also more sufficient. 2 If the content is below this, coloring of the formed anti-glare layer can be prevented.

[0174] In this manner, an anti-glare layer can be formed on the substrate. It should be noted that the anti-glare layer may also be formed by a manufacturing method other than the above-described method. The hardness of the anti-glare layer of this embodiment is preferably a pencil hardness of 2H or more, although this is also affected by the thickness of the layer.

[0175] In this embodiment, the anti-glare layer may have a multi-layer structure in which two or more layers are stacked.

[0176] In this embodiment, the above-mentioned AR layer (low refractive index layer) may be disposed on the anti-glare layer. For example, when the optical semiconductor element encapsulation sheet according to this embodiment is attached to a self-luminous display device, one of the factors that reduces the visibility of the image is the reflection of light at the interface between air and the anti-glare layer. The AR layer reduces the surface reflection. Note that the anti-glare layer and the anti-reflection layer may each have a multi-layer structure in which two or more layers are stacked.

[0177] In order to prevent adhesion of contaminants and to improve the ease of removal of adhered contaminants, it is preferable to laminate an anti-contamination layer formed from a fluorine group-containing silane compound or a fluorine group-containing organic compound on the anti-glare layer.

[0178] In this embodiment, it is preferable to perform a surface treatment on at least one of the substrate and the anti-glare layer. By performing a surface treatment on the substrate surface, adhesion to the anti-glare layer is further improved. Furthermore, by performing a surface treatment on the anti-glare layer surface, adhesion to the AR layer is further improved.

[0179] In order to prevent the substrate from curling, the other surface of the anti-glare layer may be subjected to a solvent treatment, and a transparent resin layer may be formed on the other surface of the anti-glare layer to prevent curling.

[0180] <Production of optical semiconductor element encapsulation sheets> The optical semiconductor element encapsulation sheet can be prepared by laminating a diffusion layer and an antireflection layer. Specifically, the sheet-like diffusion layer and the antireflection layer can be prepared separately and then bonded together.

[0181] The diffusion layer and the antireflection layer can be obtained by applying a composition for forming a resin layer (an ionizing radiation-curable resin composition, a pressure-sensitive adhesive composition) in the form of a sheet (layer) onto a release film, and curing the coating film on the release film by heating and / or irradiating it with ultraviolet light.

[0182] When photocuring is performed, it is preferable to further attach a release film to the surface of the coating film and irradiate the photocurable pressure-sensitive adhesive composition with ultraviolet light while sandwiched between two release films to prevent polymerization inhibition by oxygen. Before photocuring, the sheet-like coating film may be heated for the purpose of removing the solvent or dispersion medium, etc. When removing the solvent, etc. by heating, it is preferable to perform this before attaching the release film.

[0183] Films made of various resin materials are used as the film substrate of the release film. Examples of resin materials include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Among these, polyester resins such as polyethylene terephthalate are particularly preferred. The thickness of the film substrate is preferably 10 to 200 μm, more preferably 25 to 150 μm. Examples of materials for the release layer include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, and fatty acid amide-based release agents. The thickness of the release layer is generally about 10 to 2,000 nm.

[0184] The composition can be applied to the release film by various methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0185] By irradiating the composition coated in a layer on the release film with ultraviolet light, active species are generated from the photopolymerization initiator, the photopolymerizable compound is polymerized, and as the polymerization rate increases (the amount of unreacted monomer decreases), the liquid composition becomes a solid (regular) resin layer. The light source for ultraviolet irradiation is not particularly limited as long as it can irradiate light in the wavelength range to which the photopolymerization initiator contained in the composition is sensitive, and examples thereof include an LED light source, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, and a xenon lamp.

[0186] The cumulative amount of irradiation light is, for example, 100 to 5000 mJ / cm 2 The polymerization rate (non-volatile content) of the pressure-sensitive adhesive layer made of the photocured composition is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The polymerization rate may be 93% or more or 95% or more. In order to reduce the non-volatile content, the pressure-sensitive adhesive layer may be heated to remove volatile content such as residual monomers, unreacted polymerization initiator, and solvent.

[0187] The heating temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. An appropriate heating time can be adopted as needed. The heating time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 15 minutes, and particularly preferably 10 seconds to 10 minutes.

[0188] When release films are provided on both sides of the pressure-sensitive adhesive layer, the thickness of one release film and the thickness of the other release film may be the same or different. The peel force when peeling the release film temporarily attached to one side from the resin layer and the peel force when peeling the release film temporarily attached to the other side from the resin layer may be the same or different. When the two release forces are different, the release film with a relatively small peel force (light release film) is peeled first, and then the exposed diffusion layer and antireflection layer are attached, thereby producing a sheet for encapsulating optical semiconductor elements in which the diffusion layer and the antireflection layer are adjacent and directly laminated.

[0189] When the sheet for encapsulating optical semiconductor elements of the present invention is in a form in which a diffusion layer and an antireflection layer are laminated via a substrate, a release film with a relatively small peel strength (light release film) is first peeled off, and then the exposed diffusion layer and antireflection layer are attached to the front and back surfaces of the substrate, respectively, thereby making it possible to produce a sheet for encapsulating optical semiconductor elements in which a diffusion layer and an antireflection layer are laminated via a substrate.

[0190] In the optical semiconductor element encapsulation sheet of the present invention, the diffusion layer and the antireflection layer are preferably adjacent to each other. That is, the diffusion layer and the antireflection layer are preferably adjacent to each other and directly laminated to each other. This configuration is advantageous in terms of reducing color cast in mini / micro LED display devices. That is, if the diffusion layer and the antireflection layer are laminated via another layer structure, it becomes difficult to control the reflection and diffusion of light emitted from the optical semiconductor elements of the mini / micro LED display device, and it tends to be difficult to prevent color cast.

[0191] The shear storage modulus G'25°C of the diffusion layer and anti-reflection layer at a temperature of 25°C is, for example, about 10 to 1,000 kPa, and may be 30 kPa or more, 50 kPa or more, 70 kPa or more, or 100 kPa or more, and may be 700 kPa or less, 500 kPa or less, 300 kPa or less, or 200 kPa or less. The shear storage modulus G'85°C of the diffusion layer and anti-reflection layer at a temperature of 85°C is, for example, about 3 to 300 kPa, and may be 5 kPa or more, 7 kPa or more, or 10 kPa or more, and may be 200 kPa or less, 150 kPa or less, or 100 kPa or less. A shear storage modulus within the above range can achieve both appropriate flexibility and adhesiveness. The shear storage modulus is a value measured by dynamic viscoelasticity measurement at a frequency of 1 Hz.

[0192] The optical semiconductor element encapsulation sheet of the present invention may have a release film provided on the diffusion layer and / or antireflection layer until use. Furthermore, when the optical semiconductor element encapsulation sheet of the present invention has a substrate, a surface protective film may be laminated on the substrate. The surface protective film is suitable for preventing scratches and dirt from adhering to the optical semiconductor element encapsulation sheet and optical products containing the same during production, transportation, and shipping.

[0193] <Optical semiconductor devices, self-luminous display devices, image display devices> The optical semiconductor device of the present invention comprises a substrate, one or more optical semiconductor elements arranged on the substrate, and the sheet for encapsulating an optical semiconductor element of the present invention, wherein the sheet for encapsulating an optical semiconductor element encapsulates the optical semiconductor elements. The optical semiconductor device of the present invention is preferably a self-luminous display device. The image display device of the present invention preferably comprises the self-luminous display device of the present invention.

[0194] The optical semiconductor device (self-luminous display device) of the present invention is a display device in which a large number of minute optical semiconductor elements are arranged on a wiring substrate, and each optical semiconductor element is selectively made to emit light by a light-emission control means connected to the optical semiconductor element, thereby directly displaying visual information such as text, images, and videos on a display screen by blinking each optical semiconductor element. Examples of self-luminous display devices include mini / micro LED display devices and organic EL (electroluminescence) display devices. The optical semiconductor element encapsulation sheet of the present invention is particularly suitable for use in the manufacture of mini / micro LED display devices.

[0195] 3 and 4 are schematic diagrams (cross-sectional views) showing an embodiment of a self-luminous display device (mini / micro LED display device) of the present invention. In Fig. 3, a self-luminous display device (mini / micro LED display device) 20 includes a display panel in which a plurality of LED chips 5 are arranged on one surface of a substrate 3, and an optical semiconductor element encapsulation sheet 10 of the present invention. The LED chips 5 on the substrate 3 are encapsulated by an antireflection layer 2 of the optical semiconductor element encapsulation sheet 10. In Fig. 4, a self-luminous display device (mini / micro LED display device) 21 includes a display panel in which a plurality of LED chips 5 are arranged on one surface of a substrate 3, and an optical semiconductor element encapsulation sheet 10 of the present invention. The LED chips 5 on the substrate 3 are encapsulated by a diffusion layer 1 of the optical semiconductor element encapsulation sheet 10.

[0196] In this embodiment, a metal wiring layer 4 for sending light emission control signals to each LED chip 5 is laminated on the substrate 3 of the display panel. The LED chips 5 emitting light of red (R), green (G), and blue (B) are alternately arranged on the substrate 3 of the display panel via the metal wiring layer 4. The metal wiring layer 4 is made of a metal such as copper, and reflects external light, reducing the visibility of images. In addition, the light emitted by each LED chip 5 of each color (RGB) mixes, reducing contrast.

[0197] In the mini / micro LED display device 20 of Figure 3, the anti-reflection layer 2 seals the spaces between the LED chips 5 arranged on the display panel and the metal wiring layer 4. The anti-reflection layer 2, which has a higher light-blocking property (lower transmittance) than the diffusion layer 1, seals the spaces between the LED chips 5 without any gaps, preventing color mixing between the LED chips 5 and improving contrast. In addition, the anti-reflection layer 2, which has a higher light-blocking property (lower transmittance) than the diffusion layer 1, also seals the surface of the metal wiring layer 4, preventing reflection from the metal wiring layer 4.

[0198] 3, the diffusion layer 1 seals the top (display image side) of each LED chip 5 arranged on the display panel. The haze value of the diffusion layer 1 is higher than that of the anti-reflection layer 2, and therefore the diffusion layer 1 has sufficient light diffusion performance. Because the diffusion layer 1, which has a higher haze value than the anti-reflection layer 2, seals the top (display image side) of each LED chip 5, the visible light emitted from each LED chip 5 is sufficiently diffused, and color cast can be efficiently reduced.

[0199] In the mini / micro LED display device 21 of Figure 4, the diffusion layer 1 seals the spaces between the LED chips 5 arranged on the display panel and the metal wiring layer 4. The diffusion layer 1, which has a higher haze value than the anti-reflection layer 2, seals the spaces between the LED chips 5 without any gaps, so that the strong light emitted from the side of each LED chip 5 can be efficiently diffused and uniformed, and color cast can be efficiently reduced.

[0200] 4, the antireflection layer 2 seals the top (display image side) of each LED chip 5 arranged on the display panel. The total light transmittance of the antireflection layer 2 is lower than that of the diffusion layer 1, and therefore has sufficient light-blocking performance. Because the antireflection layer 2, which has a lower total light transmittance than the diffusion layer 1, seals the top (display image side) of each LED chip 5, it can sufficiently block external light reflected by the metal wiring layer 4.

[0201] As described above, the optical semiconductor element encapsulation sheet of the present invention includes an antireflection layer with higher light-blocking properties (low transmittance), thereby preventing reflection and gloss on the metal surface. When a metal adherend is laminated on the optical semiconductor element encapsulation sheet of the present invention, the reflectance over the entire light range may be, for example, 10% or less, but is preferably 8.5% or less, more preferably 8% or less, even more preferably 7.5% or less, and particularly preferably 7% or less. Note that the metal adherend can be made of copper, aluminum, stainless steel, or the like.

[0202] The image display device of this embodiment may include optical members other than the self-luminous display device and the optical semiconductor element encapsulation sheet. Examples of the optical members include, but are not limited to, polarizing plates, retardation plates, anti-reflection films, viewing angle adjusting films, and optical compensation films. The optical members also include members (such as decorative films, ornamental films, and surface protection plates) that serve to decorate and protect the display device and input device while maintaining their visibility.

[0203] The mini / micro LED display device of this embodiment can be manufactured by bonding a display panel having a plurality of LED chips arranged on one side of a substrate to a diffusion layer or anti-reflection layer of the optical semiconductor element encapsulation sheet of the present invention.

[0204] Specifically, the sheet for encapsulating an optical semiconductor element can be attached to the display panel by laminating them under heat and / or pressure. When the sheet for encapsulating an optical semiconductor element is attached to the display panel, it can be attached by laminating them under heat and / or pressure and then photocuring. The photocuring can be performed in the same manner as the photocuring for forming the diffusion layer and / or antireflection layer described above. [Example]

[0205] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Various properties in the following production examples were evaluated or measured by the following methods.

[0206] (Hayes) The haze value was measured according to the method defined in JIS 7136 using a haze meter (manufactured by Murakami Color Science Laboratory, trade name "HN-150").

[0207] (Total light transmittance) The total light transmittance was measured according to the method defined in JIS 7361 using a haze meter (manufactured by Murakami Color Science Laboratory, trade name "HN-150").

[0208] Manufacturing Example 1 (Preparation of Prepolymer) A separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube was charged with 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA, manufactured by Osaka Organic Chemical Industry, Ltd., trade name "Viscoat #155"), 19 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.09 parts by weight of a photopolymerization initiator (manufactured by IGM, trade name "Omnirad 184"), and 0.09 parts by weight of a photopolymerization initiator (manufactured by IGM, trade name "Omnirad 651"), and then nitrogen gas was introduced and the mixture was purged with nitrogen for about 1 hour while stirring. 2 The reaction rate was adjusted to 5 to 15%, and an acrylic prepolymer solution was obtained.

[0209] Manufacturing Example 2 (Preparation of Black Adhesive Composition) To the acrylic prepolymer solution obtained in Production Example 1 (total amount of prepolymers taken as 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA") as a polyfunctional monomer, 0.35 parts by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.3 parts by weight of a photopolymerization initiator (manufactured by IGM Co., Ltd., trade name "OMNIRAD 651") were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. To 100 parts by weight of the photopolymerizable pressure-sensitive adhesive composition solution obtained above, 0.2 parts by weight of a photopolymerization initiator (manufactured by IGM, product name "OMNIRAD 651") and 9.2 parts by weight of a black pigment dispersion (manufactured by Tokushiki Corporation, product name "Tokushiki 9050 Black") were added to prepare a photopolymerizable black pressure-sensitive adhesive composition solution.

[0210] Manufacturing Example 3 (Preparation of anti-reflective sheet) The black adhesive composition solution prepared in Production Example 2 was applied to the release surface of a 38 μm-thick release film R1 (manufactured by Mitsubishi Plastics, Inc., product name "MRF#38"), one side of which is a polyester film, so that the thickness after curing would be 50 μm. This was then covered with release film R2 (manufactured by Mitsubishi Plastics, Inc., MRE#38), one side of which is a polyester film, to block out air. A black light (manufactured by Toshiba, product name "FL15BL") was used from one side of this laminate to illuminate at an illuminance of 5 mW / cm. 2 , cumulative light intensity 1300mJ / cm 2 As a result, a 50 μm-thick antireflection sheet 1 in the form of a substrateless adhesive sheet was obtained, in which a photocrosslinkable adhesive, which was a cured product of the black adhesive composition, was sandwiched between the release films R1 and R2. The illuminance value of the black light is a value measured using an industrial UV checker (manufactured by Topcon Corporation, product name: UVR-T1, light receiving unit model UD-T36) with a peak sensitivity wavelength of approximately 350 nm. The haze of the anti-reflection sheet 1 was 22.2%, and the total light transmittance was 0.9%.

[0211] Production Example 4 (Preparation of anti-reflective sheet) An anti-reflection sheet 2 having a thickness of 50 μm was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 2 and 3, except that 5.8 parts by weight of a black pigment dispersion (manufactured by Tokushiki Corporation, product name "Tokushiki 9050 Black") was added. The haze of the antireflection sheet 2 was 16.9%, and the total light transmittance was 5.9%.

[0212] Manufacturing Example 5 (Preparation of anti-reflective sheet) An anti-reflection sheet 3 having a thickness of 50 μm was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 2 and 3, except that 2.3 parts by weight of a black pigment dispersion (manufactured by Tokushiki Corporation, product name "Tokushiki 9050 Black") was added. The haze of the anti-reflection sheet 3 was 8.4%, and the total light transmittance was 29.7%.

[0213] Manufacturing Example 6 (Preparation of anti-reflective sheet) An anti-reflection sheet 4 having a thickness of 50 μm was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 2 and 3, except that 1.7 parts by weight of a black pigment dispersion (manufactured by Tokushiki Corporation, product name "Tokushiki 9050 Black") was added. The haze of the anti-reflection sheet 4 was 7%, and the total light transmittance was 38.5%.

[0214] Manufacturing Example 7 (Preparation of anti-reflective sheet) An anti-reflection sheet 5 having a thickness of 50 μm was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 2 and 3, except that 3.0 parts by weight of a black pigment dispersion (manufactured by Tokushiki Corporation, product name "Tokushiki 9256 Black") was added. The haze of the antireflection sheet 5 was 9.1%, and the total light transmittance was 20.8%.

[0215] Manufacturing Example 8 (Preparation of Pressure-Sensitive Adhesive Composition) To the acrylic prepolymer solution obtained in Production Example 1 (total amount of prepolymers taken as 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA") as a polyfunctional monomer, 0.35 parts by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.3 parts by weight of a photopolymerization initiator (manufactured by IGM Co., Ltd., trade name "OMNIRAD 651") were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. To 100 parts by weight of the photopolymerizable adhesive composition solution obtained above, 1 part by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, Inc., trade name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) was added to prepare a photopolymerizable adhesive composition solution.

[0216] Manufacturing Example 9 (Preparation of light diffusion sheet) The photopolymerizable adhesive composition solution prepared in Production Example 8 was applied to the release surface of a 38 μm-thick release film R1 (manufactured by Mitsubishi Plastics, Inc., trade name "MRF#38"), one side of which is a polyester film, so that the thickness after curing would be 100 μm. This was then covered with a release film R2 (manufactured by Mitsubishi Plastics, Inc., MRE#38), one side of which is a polyester film, to block out air. A black light (manufactured by Toshiba, trade name "FL15BL") was used from one side of this laminate to illuminate at an illuminance of 5 mW / cm. 2 , cumulative light intensity 1300mJ / cm 2 As a result, a light diffusion sheet 1 having a thickness of 100 μm was obtained in the form of a substrateless adhesive sheet, in which a photocrosslinkable adhesive, which was a cured product of the photopolymerizable adhesive composition, was sandwiched between the release films R1 and R2. The illuminance value of the black light is a value measured using an industrial UV checker (manufactured by Topcon Corporation, product name: UVR-T1, light receiving unit model UD-T36) with a peak sensitivity wavelength of approximately 350 nm. The haze of the light diffusion sheet 1 was 38.4%, and the total light transmittance was 91.5%.

[0217] Manufacturing Example 10 (Preparation of light diffusion sheet) A 100 μm thick light-diffusing sheet 2 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that 2 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, product name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) were added. The haze of the light diffusion sheet 2 was 56%, and the total light transmittance was 91.3%.

[0218] Manufacturing Example 11 (Preparation of light diffusion sheet) A 100 μm thick light-diffusing sheet 3 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that 5 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, product name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) were added. The haze of the light diffusion sheet 3 was 86.6%, and the total light transmittance was 91.7%.

[0219] Manufacturing Example 12 (Preparation of light diffusion sheet) A 100 μm thick light-diffusing sheet 4 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that 60 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, Inc., trade name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) and 20 parts by weight of 3-phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate POB-A") were added. The haze of the light diffusion sheet 4 was 99.5% and the total light transmittance was 77%.

[0220] Manufacturing Example 13 (Preparation of light diffusion sheet) A 100 μm thick light-diffusing sheet 5 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that 2 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, Inc., trade name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) and 20 parts by weight of 3-phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate POB-A") were added. The haze of the light diffusion sheet 5 was 58.8%, and the total light transmittance was 90.5%.

[0221] Manufacturing Example 14 (Preparation of light diffusion sheet) A 100 μm thick light-diffusing sheet 6 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that 0.2 parts by weight of light-diffusing microparticles (manufactured by DuPont, trade name "Ti-Pure R706", titanium oxide, refractive index: approximately 2.5, average particle size: 0.36 μm) were added. The haze of the light diffusion sheet 6 was 44.8%, and the total light transmittance was 78.4%.

[0222] Manufacturing Example 15 (Preparation of light diffusion sheet) To the acrylic prepolymer solution obtained in Production Example 1 (total amount of prepolymers taken as 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA") as a polyfunctional monomer, 0.35 parts by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.3 parts by weight of a photopolymerization initiator (manufactured by IGM Co., Ltd., trade name "OMNIRAD 651") were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. To 41.3 parts by weight of the photopolymerizable pressure-sensitive adhesive composition solution obtained above, 7.18 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 21.53 parts by weight of 2-ethylhexyl acrylate (2-EHA), 0.01 part by weight of dipentaerythritol hexaacrylate (DPHA), 0.092 parts by weight of a photopolymerization initiator (manufactured by IGM, trade name "Omnirad 651"), and 30 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, trade name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. Using the photopolymerizable pressure-sensitive adhesive composition solution obtained above, a 50 μm-thick light diffusion sheet 7 sandwiched between release films R1 and R2 was obtained in the form of a substrateless pressure-sensitive adhesive sheet in the same manner as in Production Example 9. The haze of the light diffusion sheet 7 was 96.3%, and the total light transmittance was 91.8%.

[0223] Manufacturing Example 16 (Preparation of light diffusion sheet) To the acrylic prepolymer solution obtained in Production Example 1 (total amount of prepolymers taken as 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYARAD DPHA") as a polyfunctional monomer, 0.35 parts by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.3 parts by weight of a photopolymerization initiator (manufactured by IGM Co., Ltd., trade name "OMNIRAD 651") were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. To 38.2 parts by weight of the photopolymerizable pressure-sensitive adhesive composition solution obtained above, 23 parts by weight of benzyl acrylate (BZA, Viscoat #160, Osaka Organic Chemical Industry Ltd.), 15.7 parts by weight of butyl acrylate (BA), 0.02 parts by weight of dipentaerythritol hexaacrylate (DPHA), 0.092 parts by weight of a photopolymerization initiator (manufactured by IGM, trade name "Omnirad 651"), and 23 parts by weight of light-diffusing microparticles (manufactured by Momentive Performance Materials Japan, trade name "Tospearl 145", silicone resin, refractive index: 1.42, average particle size: 4.5 μm) were added to prepare a photopolymerizable pressure-sensitive adhesive composition solution. Using the photopolymerizable pressure-sensitive adhesive composition solution obtained above, a 50 μm-thick light diffusion sheet 8 sandwiched between release films R1 and R2 was obtained in the form of a substrateless pressure-sensitive adhesive sheet in the same manner as in Production Example 9. The haze of the light diffusion sheet 8 was 98.0%, and the total light transmittance was 89.5%.

[0224] Manufacturing Example 17 (Preparation of adhesive sheet) A 50 μm thick adhesive sheet 1 was obtained in the form of a substrateless adhesive sheet in the same manner as in Production Examples 8 and 9, except that no light-diffusing fine particles were added and the coating was carried out so that the thickness after curing would be 50 μm. The haze of the pressure-sensitive adhesive sheet 1 was 0.6%, and the total light transmittance was 92.4%.

[0225] Manufacturing Example 18 (Preparation of adhesive sheet) A 100 μm thick adhesive sheet 2 was obtained in the form of a substrate-less adhesive sheet in the same manner as in Production Examples 8 and 9, except that no light-diffusing fine particles were added. The haze of the pressure-sensitive adhesive sheet 2 was 0.6%, and the total light transmittance was 92.4%.

[0226] Example 1 (Preparation of Sheet for Encapsulating Optical Semiconductor Elements) One release film was peeled off from the antireflection sheet 2 obtained in Production Example 4, which had been cut to a size of 50 mm x 45 mm, to expose the adhesive surface. One release film was peeled off from the light diffusion sheet 1 obtained in Production Example 9, which had been cut to a size of 50 mm x 45 mm, to expose the adhesive surface, which was then attached to the adhesive surface of the antireflection sheet 2, to obtain a laminate 1 as a sheet for encapsulating optical semiconductor elements, consisting of release film 1 / antireflection sheet 2 / light diffusion sheet 1 / release film 2.

[0227] Examples 2 to 14, Comparative Examples 1 to 4 (Preparation of Sheet for Encapsulating Optical Semiconductor Elements) Laminates 2 to 18 were obtained in the same manner as in Example 1, except that the laminate structures shown in Tables 1 and 2 were used.

[0228] (evaluation) The following evaluations were carried out using the sheets for encapsulating optical semiconductor elements obtained in the above Examples and Comparative Examples. The evaluation methods are shown below.

[0229] (1) Hayes Release film 2 was peeled off from the optical semiconductor element encapsulation sheets obtained in Examples and Comparative Examples, and the sheets were attached to a glass plate. Release film 1 was then peeled off, and the sheets were placed in a haze meter (manufactured by Murakami Color Science Laboratory, product name "HN-150") so that light was incident from the exposed adhesive surface, and the haze value was measured according to the method specified in JIS 7136. The results are shown in Tables 1 and 2.

[0230] (2) Total light transmittance Release film 2 was peeled off from the optical semiconductor element encapsulation sheets obtained in Examples and Comparative Examples, and the sheets were attached to a glass plate. Release film 1 was then peeled off, and the sheets were placed in a haze meter (manufactured by Murakami Color Science Laboratory, product name "HN-150") so that light was incident from the exposed adhesive surface, and the total light transmittance was measured according to the method specified in JIS 7361. The results are shown in Tables 1 and 2.

[0231] (3)Reflectance Release film 2 was peeled off from the optical semiconductor element encapsulation sheets obtained in the above Examples and Comparative Examples, and the exposed adhesive surface was attached to aluminum foil. The obtained samples were placed in a Solidspec 3700 (manufactured by Shimadzu Corporation) with release film 1 facing the light source, and the reflectance (%) from 280 to 780 nm was measured. The reflectance at 550 nm is shown in Tables 1 and 2. The anti-reflection function was evaluated according to the following criteria. The results are shown in Tables 1 and 2. 〇: Reflectance at 550nm is 8.5% or less △: Reflectance at 550 nm is over 8.5% and 10% or less ×: Reflectance at 550 nm exceeds 10%

[0232] (4) Light diffusion effect The release film 2 was peeled off from the optical semiconductor element encapsulation sheets obtained in the Examples and Comparative Examples, and the sheets were attached to a glass plate. An LED lamp (manufactured by EK Japan Co., Ltd., product name "LK-3PG") was placed above the screen at a height of 2.4 cm. The glass plate side of the obtained sample was placed in close contact with the LED lamp. A battery box (manufactured by EK Japan Co., Ltd., product name "AP-180") was connected to the LED lamp, and the LED lamp was turned on. The diameter of the circular image projected on the screen was measured, and the light diffusion effect was evaluated according to the following criteria. The results are shown in Tables 1 and 2. Yes: Diameter exceeds 2cm ×: Diameter is 2cm or less

[0233] [Table 1]

[0234] [Table 2]

[0235] *In Table 2, Comparative Example 1 uses adhesive sheet 1 as the anti-reflection layer, Comparative Example 2 uses adhesive sheet 2 as the diffusion layer, Comparative Example 3 uses adhesive sheet 1 as the anti-reflection layer and adhesive sheet 2 as the diffusion layer, and Comparative Example 4 uses adhesive sheet 2 as the diffusion layer, and are denoted as T1, T2, H1, and H2, respectively.

[0236] Variations of the present invention are listed below. [Appendix 1] A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The sheet includes a diffusion layer and an anti-reflection layer, a total light transmittance T1 of the diffusion layer and a total light transmittance T2 of the antireflection layer satisfy the relationship T1>T2, The sheet for encapsulating an optical semiconductor element, wherein a haze value H1 of the diffusion layer and a haze value H2 of the antireflection layer satisfy H1>H2. [Appendix 2] The sheet for encapsulating an optical semiconductor element according to Appendix 1, wherein the haze value H1 of the diffusion layer is 30 to 99.9%. [Appendix 3] The sheet for encapsulating an optical semiconductor element according to Appendices 1 or 2, wherein the antireflection layer has a total light transmittance T2 of 1 to 30%. [Appendix 4] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 3, wherein the diffusion layer and the antireflection layer are adjacent to each other. [Appendix 5] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 4, wherein the diffusion layer is a resin layer, and the antireflection layer is a resin layer. [Appendix 6] The sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 4, wherein the diffusion layer is an adhesive layer, and the antireflection layer is an adhesive layer. [Appendix 7] A substrate, one or more optical semiconductor elements disposed on the substrate, and the sheet for encapsulating an optical semiconductor element according to any one of Appendices 1 to 6, The optical semiconductor device, wherein the optical semiconductor element encapsulation sheet encapsulates the optical semiconductor element. [Appendix 8] The optical semiconductor device according to appendix 7, which is a self-luminous display device. [Appendix 9] An image display device comprising the self-luminous display device according to appendix 8. [Industrial Applicability]

[0237] The sheet for encapsulating an optical semiconductor element of the present invention is suitable for encapsulating an optical semiconductor element of a self-luminous display device such as a mini / micro LED. [Explanation of symbols]

[0238] 10, 11 Optical semiconductor element encapsulation sheet 1 Diffusion layer 2 Anti-reflection layer S base material 20, 21 Self-luminous display devices (mini / micro LED display devices) 3. Circuit Board 4 Metal wiring layer 5. Optical semiconductor device (LED chip)

Claims

1. A sheet for encapsulating one or more optical semiconductor elements arranged on a substrate, The sheet includes a diffusion layer and an anti-reflection layer, The total light transmittance T of the diffusion layer 1 and the total light transmittance T of the antireflection layer 2 Is T 1 >T 2 and The haze value H of the diffusion layer 1 and the haze value H of the antireflection layer 2 Is, H 1 >H 2 A sheet for encapsulating optical semiconductor elements that satisfies the above requirements.

2. The haze value H of the diffusion layer 1 The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the surface roughness is 30 to 99.9%.

3. The total light transmittance T of the antireflection layer 2 The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the content of the polymerizable organic solvent is 1 to 30%.

4. The total light transmittance T of the antireflection layer 2 The sheet for encapsulating an optical semiconductor element according to claim 2, wherein the content of the polymerizable organic solvent is 1 to 30%.

5. 5. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the diffusion layer and the antireflection layer are adjacent to each other.

6. 5. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the diffusion layer is a resin layer, and the antireflection layer is a resin layer.

7. 5. The sheet for encapsulating an optical semiconductor element according to claim 1, wherein the diffusion layer is a pressure-sensitive adhesive layer, and the antireflection layer is a pressure-sensitive adhesive layer.

8. A substrate, one or more optical semiconductor elements disposed on the substrate, and the optical semiconductor element encapsulation sheet according to any one of claims 1 to 4, The optical semiconductor device, wherein the optical semiconductor element encapsulation sheet encapsulates the optical semiconductor element.

9. 9. The optical semiconductor device according to claim 8, which is a self-luminous display device.

10. An image display device comprising the self-luminous display device according to claim 9.

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