JP2024053460A - Optical semiconductor element encapsulation sheet and display body - Google Patents

Abstract

The present invention provides a sheet for encapsulating optical semiconductor elements, which, when encapsulating an optical semiconductor element, causes little change in the color of light emitted from the optical semiconductor element even when the sheet is subjected to an external impact.
[Solution] The sheet 1 for encapsulating optical semiconductor elements is a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate. The sheet 1 for encapsulating optical semiconductor elements includes a base film 2 and a colored adhesive layer 4 laminated on the base film 2. When the storage modulus E (MPa) of the base film 2 at 25°C, the thickness h (mm), and the distance from the upper edge of the base film 2 to the neutral axis are λ (mm), the base film 2 satisfies E×(h−λ) ³ ≧1.0.
[Selected Figure] Figure 1

Description

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

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. In the basic configuration of a mini/micro LED display device, a substrate on which numerous tiny optical semiconductor elements (LED chips) are densely arranged is used as the display panel, and the optical semiconductor elements are sealed with a sealant, with a cover member such as a resin film or glass plate laminated on the outermost layer.

In displays equipped with 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 substrate of the display panel. Such display devices have a problem in that, for example, when the light is turned off, the light is reflected by the metal wiring, making the screen look bad and inferior in design. For this reason, technology is being adopted that uses an anti-reflection layer to prevent reflection by the metal wiring as a sealant for sealing optical semiconductor elements.

Patent document 1 discloses an adhesive sheet that is a laminate of a colored adhesive layer and a colorless adhesive layer, with the colorless adhesive layer positioned so as to contact an optical semiconductor element. It is described that the adhesive sheet described above, when brought into contact with and conforming to the uneven shape formed by a substrate and an optical semiconductor element mounted on the substrate, can improve the design when the display is turned off and can also suppress uneven brightness.

JP 2020-169262 A

When an optical semiconductor element is sealed with an adhesive sheet having a colored adhesive layer, the colored adhesive layer may deform upon receiving an external impact. When the colored adhesive layer deforms, there is a problem in that the color of the light emitted by the optical semiconductor element changes.

The present invention was conceived under these circumstances, and its purpose is to provide a sheet for sealing optical semiconductor elements that, when the optical semiconductor elements are sealed, is less likely to change color in the light emitted by the optical semiconductor elements even when the sheet is subjected to an external impact.

As a result of intensive research into achieving the above object, the present inventors have found that a sheet for encapsulating optical semiconductor elements, comprising a base film and a colored pressure-sensitive adhesive layer laminated on the base film, wherein the base film satisfies E×(h−λ) ³ ≧1.0, makes it difficult for the color of light emitted by the optical semiconductor element to change even when the sheet is subjected to an external impact while encapsulating the optical semiconductor element. The present invention was completed based on these findings.

That is, the present invention provides a sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, comprising:
The sheet includes a base film and a colored adhesive layer laminated on the base film,
The present invention provides a sheet for encapsulating optical semiconductor elements, in which the base film satisfies E×(h−λ) ³ ≧1.0, where E (MPa) is the storage modulus of the base film at 25° C., h (mm) is the thickness, and λ (mm) is the distance from the upper edge of the base film to the neutral axis.

The sheet for encapsulating optical semiconductor elements has the colored pressure-sensitive adhesive layer, which allows it to exhibit an anti-reflection function when encapsulating an optical semiconductor element. Also, by encapsulating an optical semiconductor element such that a base film satisfying E×(h−λ) ³ ≧1.0 is on the front side of the colored pressure-sensitive adhesive layer, the colored pressure-sensitive adhesive layer can be protected from impact, and deformation of the colored pressure-sensitive adhesive layer when subjected to an external impact can be suppressed, making it difficult for the color to change.

The optical semiconductor element encapsulation sheet preferably further comprises a non-colored adhesive layer between the base film and the colored adhesive layer. With such a configuration, the non-colored adhesive layer can absorb external impacts, and deformation of the colored adhesive layer can be further suppressed.

It is preferable that the thickness of the base film is 150 to 500 μm and the storage modulus of the base film is 1.8 to 10 GPa. With such a configuration, the base film can better absorb external impacts and can further suppress deformation of the colored adhesive layer.

The thickness of the non-colored adhesive layer is preferably 100 to 200 μm. With this configuration, the non-colored adhesive layer can better absorb external impacts and can better suppress deformation of the colored adhesive layer.

The total light transmittance of the colored adhesive layer is preferably 5 to 99%. With this configuration, it is possible to further suppress changes in the color of the light emitted by the optical semiconductor element.

The present invention also provides a display comprising a substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet or a cured product thereof that encapsulates the optical semiconductor element. With such a display, the color of the light emitted by the optical semiconductor element is unlikely to change even when the display receives an external impact.

The display preferably comprises a self-luminous display device.

The display is preferably an image display device.

According to the sheet for encapsulating optical semiconductor elements of the present invention, when an optical semiconductor element is encapsulated, the color of the light emitted by the optical semiconductor element is unlikely to change even if the optical semiconductor element is subjected to an external impact.

1 is a cross-sectional view of a sheet for encapsulating an optical semiconductor element according to one embodiment of the present invention. FIG. 3 is a cross-sectional view of a sheet for encapsulating an optical semiconductor element according to another embodiment of the present invention. FIG. 4 is a cross-sectional view of a sheet for encapsulating an optical semiconductor element according to still another embodiment of the present invention. 2 is a partial cross-sectional view showing one embodiment of a display using the optical semiconductor element encapsulation sheet shown in FIG. 1. 4 is a partial cross-sectional view showing another embodiment of a display body using the optical semiconductor element encapsulation sheet shown in FIG. 1 .

[Optical semiconductor element encapsulation sheet]
The sheet for encapsulating optical semiconductor elements of the present invention comprises at least a base film and a colored adhesive layer laminated on the base film. In this specification, the sheet for encapsulating optical semiconductor elements refers to a sheet for encapsulating one or more optical semiconductor elements arranged on a substrate with an adhesive layer including the colored adhesive layer. In this specification, "encapsulating an optical semiconductor element" refers to embedding at least a part of the optical semiconductor element in the adhesive layer or covering the optical semiconductor element with the adhesive layer. The adhesive layer has flexibility that allows embedding at least a part of the optical semiconductor element or covering the optical semiconductor element with the adhesive layer.

The optical semiconductor element encapsulation sheet preferably further comprises a non-colored adhesive layer. In particular, it is preferable to provide a non-colored adhesive layer between the base film and the colored adhesive layer. With such a configuration, the non-colored adhesive layer can absorb external impacts, and deformation of the colored adhesive layer can be further suppressed. In addition, a non-colored adhesive layer may be provided on the optical semiconductor element side of the colored adhesive layer.

The base film, the colored adhesive layer, and the non-colored adhesive layer may each be a single layer, or multiple layers having the same or different compositions. When multiple colored adhesive layers and non-colored adhesive layers are included, the multiple layers may be laminated in contact with each other, or may be laminated separately (for example, two colored adhesive layers laminated via one non-colored adhesive layer). Each of the non-colored adhesive layers may independently be a diffusion functional layer or a non-diffusion functional layer, as described below.

Figure 1 is a cross-sectional view showing one embodiment of the sheet for encapsulating optical semiconductor elements of the present invention. As shown in Figure 1, the sheet for encapsulating optical semiconductor elements 1 can be used to encapsulate one or more optical semiconductor elements arranged on a substrate, and includes a base film 2, a colored adhesive layer 4 laminated to the base film 2, and a non-colored adhesive layer 3 located between the base film 2 and the colored adhesive layer 4. The colored adhesive layer 4 is laminated directly to the non-colored adhesive layer 3, and the non-colored adhesive layer 3 is laminated directly to the colored adhesive layer 4. A release liner 5 is attached to the colored adhesive layer 4, and the base film 2 is attached to the non-colored adhesive layer 3. Both the non-colored adhesive layer 3 and the colored adhesive layer 4 are non-diffusion functional layers.

The sheet for sealing optical semiconductor elements may have a diffusion functional layer. With such a configuration, the light emitted by the optical semiconductor element can be diffused in the diffusion functional layer, and the front brightness can be increased. The diffusion functional layer may be a layer corresponding to the colored adhesive layer, or may be a layer corresponding to the non-colored adhesive layer.

When the optical semiconductor element encapsulation sheet includes the diffusion functional layer, the encapsulation resin layer preferably includes, from the optical semiconductor element side, the diffusion functional layer, the colored adhesive layer, and the non-colored adhesive layer in this order. The non-colored adhesive layer may be either a diffusion functional layer or a non-diffusion functional layer. With this configuration, the front luminance can be increased while the appearance of the display body can be improved both when the light is off and when the light is on.

(Base film)
The substrate film is located on the opposite side of the colored adhesive layer or the non-colored adhesive layer from the optical semiconductor element side when the optical semiconductor element is encapsulated with the optical semiconductor element encapsulation sheet. In addition, by forming an anti-glare layer or an anti-reflection layer described below on the substrate film, anti-glare properties or anti-reflection properties can be imparted to the display. In addition, the substrate film serves as a support for the colored adhesive layer or the non-colored adhesive layer in the optical semiconductor element encapsulation sheet, and by providing the substrate film, the optical semiconductor element encapsulation sheet has excellent handleability.

The base film satisfies E×(h−λ)3 ≧1.0, where E is the storage modulus (MPa) of the base film at 25° C., h is the thickness (mm), and λ is the distance from the upper edge of the base film to the neutral axis (mm). By encapsulating an optical semiconductor element with a base film that satisfies E×(h−λ) ³ ≧ ^1.0 on the front side of the colored adhesive layer, the colored adhesive layer can be protected from impact, deformation of the colored adhesive layer when subjected to an external impact can be suppressed, and color change can be suppressed.

With respect to the above-mentioned base film, Ex(h-λ) ³ is 1.0 or more, preferably 1.3 or more, more preferably 1.7 or more, and even more preferably 2.0 or more. The above-mentioned Ex(h-λ) ³ is preferably 10 or less, more preferably 8 or less, and particularly preferably 6 or less. When the above-mentioned Ex(h-λ) ³ is 10 or less, the sheet for encapsulating optical semiconductor elements is easily attached to other layers, and the sheet has excellent flexibility. The above-mentioned Ex(h-λ) ³ is a formula related to the rigidity of the film against bending.

The base film may be a single layer, or may be a multi-layer film having the same composition or different thicknesses. When the base film is a multi-layer film, each layer may be bonded to another layer such as an adhesive layer. When the base film is a multi-layer film, at least one layer of the base film may satisfy E×(h−λ) ³ ≧1.0. The base film is a part that is attached to a substrate having an optical semiconductor element together with a colored adhesive layer and a non-colored adhesive layer, and the release liner that is peeled off when the sheet for encapsulating an optical semiconductor element is used (attached) and the surface protection film that merely protects the surface of the base film are not included in the “base film”.

Examples of the above-mentioned substrate films include glass and plastic substrates (especially plastic films). Examples of the resin constituting the plastic substrate include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ionomers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random, alternating) copolymers, ethylene-vinyl acetate copolymers (EVA), ethylene-propylene copolymers, cyclic olefin polymers, ethylene-butene copolymers, and ethylene-hexene copolymers; polyurethanes; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonates; polyimide resins; polyether ether ketones; polyetherimides; polyamides such as aramids and fully aromatic polyamides; polyphenyl sulfides; fluororesins; polyvinyl chloride; polyvinylidene chloride; cellulose resins such as triacetyl cellulose (TAC); silicone resins; acrylic resins such as polymethyl methacrylate (PMMA); polysulfones; polyarylates; and polyvinyl acetates. The above resins may be used alone or in combination. The substrate film may be an anti-reflection (AR) film, a polarizing plate, a retardation plate, or any other optical film.

The storage modulus of the base film is preferably 1.8 to 10 GPa, more preferably 2 to 9 GPa, and even more preferably 2.5 to 8 GPa. When the storage modulus is 1.8 GPa or more, the base film can better absorb external impacts and can better suppress deformation of the colored adhesive layer. When the storage modulus is 10.0 GPa or less, lamination with other layers is easy and the sheet for encapsulating optical semiconductor elements has excellent flexibility. The storage modulus is the storage modulus at 25°C when measured under conditions of a temperature range of 0 to 100°C, a frequency of 1 Hz, a temperature rise rate of 10°C/min, and a chuck distance of 20.0 mm.

The thickness of the substrate film is preferably 150 to 500 μm, more preferably 160 to 450 μm, and even more preferably 180 to 400 μm. When the thickness is 150 μm or more, the substrate film can better absorb external impacts and can better suppress deformation of the colored adhesive layer. When the thickness is 500 μm or less, it is easy to attach it to other layers, and the sheet for encapsulating optical semiconductor elements has excellent flexibility. In addition, the display body can be made thinner.

The surface of the base film on the side having the colored adhesive layer may be subjected to a surface treatment such as a physical treatment such as corona discharge treatment, plasma treatment, sand mat processing treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, or ionizing radiation treatment; a chemical treatment such as chromate treatment; or an easy-adhesion treatment using a coating agent (primer) in order to improve adhesion and retention with the layer on the colored adhesive layer side. It is preferable that the surface treatment for improving adhesion is applied to the entire surface of the base film on the side of the colored adhesive layer.

(Colored adhesive layer)
The colored adhesive layer is a layer intended to prevent light reflection due to metal wiring or the like provided on a substrate in a display body. The colored adhesive layer is a resin layer containing at least a colorant. The colorant may be a dye or a pigment as long as it is soluble or dispersible in the colored adhesive layer. Dyes are preferred because low haze can be achieved even with a small amount of addition, and they are not prone to settling like pigments and can be easily distributed uniformly. Pigments are also preferred because they have high color expression even with a small amount of addition. When a pigment is used as a colorant, it is preferable that the pigment has low or no electrical conductivity. The colorant may be used alone or in combination with two or more types.

As the above-mentioned colorant, a black-based colorant is preferable. As the above-mentioned black-based colorant, a colorant (pigment, dye, etc.) for presenting a known or conventional black color can be used, for example, carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine soot, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, anthraquinone-based colorant, zirconium nitride, etc. can be mentioned. In addition, a colorant that functions as a black-based colorant by combining and blending colorants that present a color other than black may be used.

When the colored adhesive layer is a radiation-curable adhesive layer, the colorant preferably absorbs visible light and is transparent to light of a wavelength at which the radiation-curable adhesive layer can be cured.

From the viewpoint of imparting an appropriate anti-reflection function to the display, the content of the colorant in the colored adhesive layer is preferably 0.2% by mass or more, more preferably 0.4% by mass or more, based on 100% by mass of the total amount of the colored adhesive layer. The content of the colorant is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. The content may be appropriately set depending on the type of colorant, the color tone and light transmittance of the display, etc. The colorant may be added to the composition as a solution or dispersion dissolved or dispersed in an appropriate solvent.

The haze value (initial haze value) of the colored adhesive layer is not particularly limited, but from the viewpoint of ensuring the front brightness and visibility of the display, it is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, and particularly preferably 20% or less. In addition, from the viewpoint of efficiently reducing the brightness unevenness of the display, the haze value of the colored adhesive layer is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 8% or more, and may be 10% or more.

The total light transmittance of the colored adhesive layer is not particularly limited, but from the viewpoint of further improving the anti-reflection function of metal wiring and the like in the display and the contrast, it is preferably 99% or less, more preferably 50% or less, even more preferably 40% or less, and particularly preferably 30% or less. In addition, from the viewpoint of ensuring brightness, the total light transmittance of the colored adhesive layer is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more.

The haze value and total light transmittance of the colored adhesive layer are each values for a single layer and can be measured by the methods specified in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the colored adhesive layer, the type and amount of colorant, etc.

The storage modulus of the colored adhesive layer is preferably 5×10 ⁻⁵ to 1.2×10 ⁻⁴ GPa, more preferably 6×10 ⁻⁵ to 1.1×10 ⁻⁴ GPa, and even more preferably 7×10 ⁻⁵ to 1.0×10 ⁻⁴ GPa. When the storage modulus is 5×10 ⁻⁵ GPa or more, the colored adhesive layer is more unlikely to deform when subjected to an external impact. When the storage modulus is 1.2×10 ⁻⁴ GPa or less, the adhesive layer is easily attached to other layers, and the optical semiconductor element encapsulation sheet has excellent flexibility. The storage modulus is the storage modulus at 25° C. when the adhesive sheet laminated to a thickness of about 1 mm is sandwiched between 8 mm parallel plates and measured from −50° C. to 100° C. with an initial strain of 1%, a frequency of 1 Hz, and a heating rate of 5° C./min.

The thickness of the colored adhesive layer is preferably 10 to 100 μm, more preferably 20 to 90 μm, and even more preferably 30 to 70 μm. If the thickness is 10 μm or more, the design is more excellent. If the thickness is 100 μm or less, it is easy to achieve an appropriate total light transmittance.

(Non-colored adhesive layer)
The non-colored adhesive layer is a layer different from the colored adhesive layer, and is not intended to prevent light reflection by metal wiring or the like provided on a substrate in a display body. The non-colored adhesive layer may be a colorless layer or may be slightly colored. The non-colored adhesive layer may be, for example, a diffusion functional layer intended to perform a function of diffusing light, or may be a non-diffusion functional layer not intended to perform a function of diffusing light. The non-colored adhesive layer may be transparent or non-transparent. The non-colored adhesive layer is a resin layer composed of a resin.

The content of the colorant in the non-colored adhesive layer is preferably less than 0.2% by mass, more preferably less than 0.1% by mass, and even more preferably less than 0.05% by mass, relative to 100% by mass of the total amount of the non-colored adhesive layer, and may be less than 0.01% by mass or less than 0.005% by mass.

The total light transmittance of the non-colored adhesive layer is not particularly limited, but from the viewpoint of ensuring brightness, it is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. In addition, the total light transmittance of the non-colored adhesive layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

The total light transmittance of the above non-colored adhesive layer is a value for a single layer and can be measured by the methods specified in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the non-colored adhesive layer.

The storage modulus of the non-colored adhesive layer is preferably 9×10 ⁻⁵ to 1.3×10 ⁻⁴ GPa, more preferably 9.5×10 ⁻⁵ to 1.2×10 ⁻⁴ GPa, and even more preferably 1×10 ⁻⁴ to 1.1×10 ⁻⁴ GPa. When the storage modulus is 9×10 ⁻⁵ GPa or more, the colored adhesive layer is more unlikely to deform when subjected to an external impact. When the storage modulus is 1.3×10 ⁻⁴ GPa or less, the adhesive layer is easily attached to other layers, and the optical semiconductor element encapsulation sheet has excellent flexibility. The storage modulus is the storage modulus at 25° C. when the adhesive sheet laminated to a thickness of about 1 mm is sandwiched between 8 mm parallel plates and measured from −50° C. to 100° C. with an initial strain of 1%, a frequency of 1 Hz, and a heating rate of 5° C./min.

The thickness of the non-colored adhesive layer is preferably 100 to 200 μm. When the thickness is within the above range, the non-colored adhesive layer can better absorb external impacts and is comfortable to wear.

The colored adhesive layer and the non-colored adhesive layer may each independently be an adhesive layer that has the property of being cured by irradiation with radiation (a radiation-curable adhesive layer), or a resin layer that does not have the property of being cured by irradiation with radiation (a non-radiation-curable adhesive layer). Examples of the radiation include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays.

The adhesive constituting the colored adhesive layer and the non-colored adhesive layer may be a known or commonly used pressure-sensitive adhesive. Examples of the adhesive include acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures of these, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. Only one type of adhesive may be used, or two or more types may be used.

The acrylic resin is a polymer that contains a structural unit derived from an acrylic monomer (a monomer component having a (meth)acryloyl group in the molecule) as a structural unit of the polymer. Only one type of the acrylic resin may be used, or two or more types may be used.

The acrylic resin is preferably a polymer that contains the largest amount of structural units derived from (meth)acrylic acid esters by mass. In this specification, "(meth)acrylic" refers to "acrylic" and/or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms.

The above (meth)acrylic acid esters include, for example, hydrocarbon group-containing (meth)acrylic acid esters. Examples of the above hydrocarbon group-containing (meth)acrylic acid esters include (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group, (meth)acrylic acid esters having an alicyclic hydrocarbon group such as (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid esters having an aromatic hydrocarbon group such as (meth)acrylic acid aryl esters. Only one type of the above hydrocarbon group-containing (meth)acrylic acid esters may be used, or two or more types may be used.

Examples of the (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and ethyl (meth)acrylate. Examples of such acrylates include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

Among the above (meth)acrylic acid alkyl esters, (meth)acrylic acid alkyl esters having a linear or branched aliphatic hydrocarbon group with a carbon number of 1 to 20 (preferably 1 to 14, more preferably 2 to 10) are preferred. When the carbon number is within the above range, it is easy to adjust the glass transition temperature of the acrylic resin, and the adhesive layer can have more suitable adhesive properties.

Examples of (meth)acrylic acid esters having the above alicyclic hydrocarbon group include (meth)acrylic acid esters having a monocyclic aliphatic hydrocarbon ring, 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.

Examples of the (meth)acrylic acid ester having an aromatic hydrocarbon group include (meth)acrylic acid phenyl ester and (meth)acrylic acid benzyl ester.

The above-mentioned hydrocarbon group-containing (meth)acrylic acid ester preferably contains a (meth)acrylic acid alkyl ester having a linear or branched aliphatic hydrocarbon group, and more preferably contains a (meth)acrylic acid ester having an alicyclic hydrocarbon group. In this case, the adhesive layer has a good balance of adhesion and is more excellent in sealing the optical semiconductor element.

In order to adequately express the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesion to optical semiconductor elements, in the adhesive layer, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester in all monomer components constituting the acrylic resin is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount (100% by mass) of all monomer components. In addition, the proportion is preferably 95% by mass or less, more preferably 80% by mass or less, from the viewpoint of copolymerizing other monomer components and obtaining the effects of the other monomer components.

The proportion of (meth)acrylic acid alkyl esters having linear or branched aliphatic hydrocarbon groups in all monomer components constituting the acrylic resin is preferably 30% by mass or more, more preferably 40% by mass or more, based on the total amount (100% by mass) of all monomer components. The proportion is preferably 90% by mass or less, more preferably 70% by mass or less.

The proportion of the (meth)acrylic acid ester having an alicyclic hydrocarbon group in all monomer components constituting the acrylic resin is preferably 1% by mass or more, more preferably 5% by mass or more, based on the total amount (100% by mass) of all monomer components. The proportion is preferably 30% by mass or less, more preferably 20% by mass or less.

The acrylic resin may contain a structural unit derived from another monomer component copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester for the purpose of introducing a first functional group described below or for the purpose of modifying the cohesive force, heat resistance, etc. Examples of the other monomer components include polar group-containing monomers such as carboxy group-containing monomers, acid anhydride monomers, hydroxy group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and nitrogen atom-containing monomers. Only one type of the other monomer components may be used, or two or more types may be used.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

Examples of the hydroxy group-containing monomer include 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.

Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

Examples of the nitrogen atom-containing monomer include morpholino group-containing monomers such as (meth)acryloylmorpholine, cyano group-containing monomers such as (meth)acrylonitrile, and amide group-containing monomers such as (meth)acrylamide.

It is preferable that the polar group-containing monomer constituting the acrylic resin contains a hydroxy group-containing monomer. By using a hydroxy group-containing monomer, it is easy to introduce the first functional group described below. In addition, the acrylic resin and the pressure-sensitive adhesive layer have excellent water resistance, and the sheet for sealing optical semiconductor elements is less likely to cloud and has excellent whitening resistance even when used in a high humidity environment.

The above hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate, more preferably 4-hydroxybutyl (meth)acrylate.

In order to adequately express the basic properties of the hydrocarbon group-containing (meth)acrylic ester, such as adhesion to optical semiconductor elements, in the pressure-sensitive adhesive layer, the proportion of the polar group-containing monomer in the total monomer components (100% by mass) constituting the acrylic resin is preferably 5 to 50% by mass, more preferably 10 to 40% by mass. In particular, from the viewpoint of achieving superior water resistance in the pressure-sensitive adhesive layer, it is preferable that the proportion of the hydroxyl group-containing monomer is within the above range.

The other monomer components may further include vinyl monomers such as caprolactone adducts of (meth)acrylic acid, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene; 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, and alkoxy-substituted hydrocarbon group-containing (meth)acrylate (2-methoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, etc.).

The proportion of the other monomer components in the total monomer components (100% by mass) constituting the acrylic resin is, for example, about 3 to 50% by mass, and may be 5 to 40% by mass or 10 to 30% by mass.

The acrylic resin may contain a structural unit derived from a polyfunctional (meth)acrylate that is copolymerizable with the monomer components that constitute the acrylic resin in order to form a crosslinked structure in the polymer skeleton. Examples of the polyfunctional (meth)acrylate include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. Only one type of the polyfunctional monomer may be used, or two or more types may be used.

In order to adequately express the basic properties of the hydrocarbon group-containing (meth)acrylic acid ester, such as adhesion to optical semiconductor elements, in the adhesive layer, the proportion of the polyfunctional monomer in the total monomer components (100% by mass) constituting the acrylic resin is preferably 40% by mass or less, and more preferably 30% by mass or less.

When the pressure-sensitive adhesive layer is a radiation-curable pressure-sensitive adhesive layer, examples of the pressure-sensitive adhesive layer include a pressure-sensitive adhesive layer that contains a base polymer and a radiation-polymerizable monomer component or oligomer component having a functional group such as a radiation-polymerizable carbon-carbon double bond, and a pressure-sensitive adhesive layer that contains a polymer having a radiation-polymerizable functional group (especially an acrylic resin) as a base polymer.

The above-mentioned radiation-polymerizable functional group includes a radiation-radical polymerizable group such as a group containing a carbon-carbon unsaturated bond, such as an ethylenically unsaturated group, and a radiation-cationically polymerizable group. Examples of the above-mentioned group containing a carbon-carbon unsaturated bond include a vinyl group, a propenyl group, an isopropenyl group, an acryloyl group, and a methacryloyl group. Examples of the above-mentioned radiation-cationically polymerizable group include an epoxy group, an oxetanyl group, and an oxolanyl group. Among these, a group containing a carbon-carbon unsaturated bond is preferred, and an acryloyl group and a methacryloyl group are more preferred. The above-mentioned radiation-polymerizable functional group may be one type only or two or more types. The position of the above-mentioned radiation-polymerizable functional group may be any of the polymer side chains, the polymer main chain, and the polymer main chain terminals.

The polymer having the radiation-polymerizable functional group can be prepared, for example, by reacting a polymer having a reactive functional group (first functional group) with a compound having a functional group (second functional group) capable of reacting with the first functional group to form a bond and the radiation-polymerizable functional group while maintaining the radiation polymerizability of the radiation-polymerizable functional group. For this reason, it is preferable that the polymer having the radiation-polymerizable functional group contains a structural part derived from the polymer having the first functional group and a structural part derived from the compound having the second functional group and the radiation-polymerizable functional group.

Examples of combinations of the first functional group and the second functional group include a carboxy group and an epoxy group, an epoxy group and a carboxy group, a carboxy group and an aziridyl group, an aziridyl group and a carboxy group, a hydroxy group and an isocyanate group, and an isocyanate group and a hydroxy group. Among these, from the viewpoint of ease of reaction tracking, a combination of a hydroxy group and an isocyanate group, and a combination of an isocyanate group and a hydroxy group are preferred. The above combinations may be one type only, or two or more types.

Examples of compounds having the above-mentioned radiation-polymerizable functional group and isocyanate group include methacryloyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate (MOI), m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc. One or more of the above compounds may be used.

The content of the structural part derived from the compound having the second functional group and the radiation-polymerizable functional group in the acrylic resin having the radiation-polymerizable functional group is preferably 0.5 moles or more, more preferably 1 mole or more, even more preferably 3 moles or more, and even more preferably 10 moles or more, per 100 moles of the total amount of the structural part derived from the acrylic resin having the first functional group, from the viewpoint of further advancing the curing of the radiation-curable adhesive layer. The content is, for example, 100 moles or less.

The molar ratio of the second functional group to the first functional group in the acrylic resin having the radiation-polymerizable functional group [second functional group/first functional group] is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.2 or more, and particularly preferably 0.4 or more, from the viewpoint of further promoting the curing of the radiation-curable adhesive layer. In addition, the molar ratio is preferably less than 1.0, more preferably 0.9 or less, from the viewpoint of further reducing low molecular weight substances in the radiation-curable adhesive layer.

The acrylic resin is obtained by polymerizing the various monomer components described above. The polymerization method is not particularly limited, but examples include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method using active energy radiation (active energy radiation polymerization method). The obtained acrylic resin may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

The acrylic resin having the radiation-polymerizable functional group can be prepared, for example, by polymerizing (copolymerizing) a raw material monomer containing a monomer component having a first functional group to obtain an acrylic resin having a first functional group, and then subjecting a compound having the second functional group and a radiation-polymerizable functional group to a condensation reaction or addition reaction with the acrylic resin while maintaining the radiation polymerizability of the radiation-polymerizable functional group.

When polymerizing the monomer components, various common solvents may be used. Examples of the solvent include organic solvents such as esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. Only one of the above solvents may be used, or two or more of them may be used.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization of the monomer components are not particularly limited and can be selected as appropriate. The weight average molecular weight of the acrylic resin can be controlled by the amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the amount used is adjusted appropriately depending on the type of these.

As the polymerization initiator used for the polymerization of the monomer components, a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) can be used depending on the type of polymerization reaction. Only one type of the above polymerization initiator may be used, or two or more types may be used.

The thermal polymerization initiator is not particularly limited, but examples thereof include azo-based polymerization initiators, peroxide-based polymerization initiators, and redox-based polymerization initiators. The amount of the thermal polymerization initiator used is preferably 1 part by mass or less, more preferably 0.005 to 1 part by mass, and even more preferably 0.02 to 0.5 parts by mass, per 100 parts by mass of the total amount of all monomer components constituting the acrylic resin having the first functional group.

Examples of the photopolymerization initiator 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, acylphosphine oxide-based photopolymerization initiators, and titanocene-based photopolymerization initiators. Among these, acetophenone-based photopolymerization initiators are preferred.

Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and methoxyacetophenone.

The amount of the photopolymerization initiator used is preferably 0.005 to 1 part by mass, more preferably 0.01 to 0.7 parts by mass, and even more preferably 0.18 to 0.5 parts by mass, relative to 100 parts by mass of the total amount of all monomer components constituting the acrylic resin. When the amount used is 0.005 parts by mass or more (particularly, 0.18 parts by mass or more), it is easier to control the molecular weight of the acrylic resin to a small value, and the residual stress of the adhesive layer tends to be higher, resulting in better step absorbency.

The reaction between the acrylic resin having the first functional group and the compound having the second functional group and the radiation-polymerizable functional group can be carried out, for example, in a solvent by stirring in the presence of a catalyst. Examples of the solvent include those mentioned above. The catalyst is appropriately selected depending on the combination of the first functional group and the second functional group. The reaction temperature in the reaction is, for example, 5 to 100°C, and the reaction time is, for example, 1 to 36 hours.

The acrylic resin may have a structural portion derived from a crosslinking agent. For example, the acrylic resin may be crosslinked to further reduce low molecular weight substances in the pressure-sensitive adhesive layer. The weight average molecular weight of the acrylic resin may also be increased. When the acrylic resin has a radiation-polymerizable functional group, the crosslinking agent crosslinks functional groups other than the radiation-polymerizable functional group (for example, between first functional groups, between second functional groups, or between a first functional group and a second functional group). Only one type of crosslinking agent may be used, or two or more types may be used.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, silicone-based crosslinking agents, and silane-based crosslinking agents. Among these crosslinking agents, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred, and isocyanate-based crosslinking agents are more preferred, from the viewpoints of excellent adhesion to optical semiconductor elements and low impurity ions.

Examples of the isocyanate-based crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of the isocyanate crosslinking agent include a trimethylolpropane/tolylene diisocyanate adduct, a trimethylolpropane/hexamethylene diisocyanate adduct, and a trimethylolpropane/xylylene diisocyanate adduct.

The content of the structural part derived from the crosslinking agent is not particularly limited, but is preferably 5 parts by mass or less, more preferably 0.001 to 5 parts by mass, and even more preferably 0.01 to 3 parts by mass, per 100 parts by mass of the total amount of the acrylic resin excluding the structural part derived from the crosslinking agent.

The adhesive layer may contain other components in addition to the above-mentioned components in each layer, as long as the effects of the present invention are not impaired. Examples of the other components include curing agents, crosslinking accelerators, tackifier resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), oligomers, antioxidants, fillers (metal powders, organic fillers, inorganic fillers, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, granular materials, foil-like materials, etc. Only one type of the other components may be used, or two or more types may be used.

(Diffusion functional layer)
The diffusion functional layer is a layer intended to diffuse light. When the diffusion functional layer is included, the light emitted from the optical semiconductor element is diffused in the diffusion functional layer, and for example, the light emitted from the side surface of the optical semiconductor element is emitted in the front direction of the display body, improving the front brightness of the display body. The diffusion functional layer is not limited, but preferably contains light diffusing fine particles. That is, the diffusion functional layer preferably contains light diffusing fine particles dispersed in the diffusion functional layer. The light diffusing fine particles may be used in one type or in two or more types.

The light-diffusing fine particles have an appropriate refractive index difference with the resin constituting the diffusion functional layer, and impart diffusion performance to the diffusion functional layer. Examples of light-diffusing fine particles include inorganic fine particles and polymer fine particles. Examples of materials for inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and metal oxides. Examples of materials for polymer fine particles include silicone resin, acrylic resin (including polymethacrylate resin such as polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin.

As the polymeric fine particles, fine particles composed of silicone resin are preferable. As the inorganic fine particles, fine particles composed of metal oxide are preferable. As the metal oxide, titanium oxide and barium titanate are preferable, and titanium oxide is more preferable. By having such a configuration, the light diffusion property of the diffusion functional layer is excellent, and brightness unevenness is further suppressed.

The shape of the light-diffusing microparticles is not particularly limited and may be, for example, spherical, flat, or irregular.

From the viewpoint of imparting appropriate light diffusion performance, the average particle diameter of the light diffusing microparticles 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. In addition, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image, the average particle diameter of the light diffusing microparticles is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. The average particle diameter can be measured, for example, using a Coulter counter.

The refractive index of the light diffusing fine particles is preferably 1.2 to 5, more preferably 1.25 to 4.5, even more preferably 1.3 to 4, and particularly preferably 1.35 to 3.

The absolute value of the refractive index difference between the light diffusing microparticles and the resin constituting the diffusion functional layer (the resin layer in the diffusion functional layer excluding the light diffusing microparticles) is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.02 or more, and particularly preferably 0.03 or more, and may be 0.04 or more, or 0.05 or more, from the viewpoint of more efficiently reducing the brightness unevenness of the display body. Furthermore, the absolute value of the refractive index difference between the light diffusing microparticles and the resin 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.

From the viewpoint of imparting appropriate light diffusion performance to the sheet for encapsulating optical semiconductor elements, the content of the light diffusing fine particles in the diffusion functional layer is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.15 parts by mass or more, relative to 100 parts by mass of the resin constituting the diffusion functional layer. Furthermore, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image, the content of the light diffusing fine particles is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, relative to 100 parts by mass of the resin constituting the diffusion functional layer.

The haze value (initial haze value) of the diffusion functional layer is not particularly limited, but from the viewpoint of efficiently reducing brightness unevenness, 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, 90% or more, 95% or more, or 97% or more, and a value around 99.9% is more preferable because it has a superior effect of improving brightness unevenness. The upper limit of the haze value of the diffusion functional layer is not particularly limited, that is, it may be 100%.

The total light transmittance of the diffusion functional layer is not particularly limited, but from the viewpoint of ensuring brightness, it is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. In addition, the upper limit of the total light transmittance of the diffusion functional layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

The haze value and total light transmittance of the diffusion functional layer are the values for a single layer and can be measured by the methods specified in JIS K7136 and JIS K7361-1, and can be controlled by the type and thickness of the diffusion functional layer, the type and amount of light-diffusing fine particles, etc.

(Non-diffusion functional layer)
The haze value (initial haze value) of the non-diffusion functional layer is not particularly limited, but from the viewpoint of improving the brightness of the display, it is preferably less than 30%, more preferably 10% or less, even more preferably 5% or less, particularly preferably 1% or less, and may be 0.5% or less. The lower limit of the haze value of the non-diffusion functional layer is not particularly limited.

The total light transmittance of the non-diffusion functional layer is not particularly limited, but from the viewpoint of ensuring the brightness of the display, it is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. In addition, the upper limit of the total light transmittance of the non-diffusion functional layer is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less.

The haze value and total light transmittance of the non-diffusion functional layer are values for a single layer, and can be measured by the methods specified in JIS K7136 and JIS K7361-1. They can be controlled by the type and thickness of the non-diffusion functional layer.

From the viewpoint of improving the brightness of the display, the content of the colorant and/or light-diffusing fine particles in the non-diffusion functional layer is preferably less than 0.01 parts by mass, and more preferably less than 0.005 parts by mass, per 100 parts by mass of the resin constituting the non-diffusion functional layer.

<Optical semiconductor element encapsulation sheet>
The optical semiconductor element encapsulation sheet may have a layer having anti-glare properties and/or anti-reflection properties. By having such a configuration, gloss and light reflection can be suppressed when encapsulating an optical semiconductor element, and the appearance can be improved. An example of the layer having anti-glare properties is an anti-glare treatment layer. An example of the layer having anti-reflection properties is an anti-reflection treatment layer. The anti-glare treatment and the anti-reflection treatment can be performed by known or conventional methods. The layer having anti-glare properties and the layer having anti-reflection properties may be the same layer or different layers. The layer having anti-glare properties and/or anti-reflection properties may have only one layer or two or more layers. The layer having anti-glare properties is preferably provided on the surface of the substrate film opposite to the side where the colored adhesive layer is located.

The haze value (initial haze value) of the optical semiconductor element encapsulation sheet is not particularly limited, but from the viewpoint of suppressing luminance unevenness and achieving a superior design, it is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more. There is no particular upper limit to the haze value.

The total light transmittance of the sheet for encapsulating optical semiconductor elements is not particularly limited, but from the viewpoint of further improving the anti-reflection function of metal wiring and the like and the contrast, it is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less. In addition, from the viewpoint of ensuring brightness, the total light transmittance is preferably 0.5% or more.

The haze value and total light transmittance can be measured by the methods specified in JIS K7136 and JIS K7361-1, respectively, and can be controlled by the lamination order, type, thickness, etc. of the layers constituting the encapsulating resin layer and the base material.

When the optical semiconductor element encapsulation sheet is attached to a glass plate and a pencil scratch hardness test is performed on the surface of the sheet using a pencil (pencil hardness 3H) with a load of 500 g, it is preferable that no change in color is observed. The temperature and humidity of the usage environment for the above test conform to JIS-K5600.

In addition, the amount of indentation of the colored adhesive layer after carrying out the pencil scratch hardness test is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. The amount of indentation is not particularly limited, but may be 0 μm or more. If the amount of indentation of the colored adhesive layer is 10 μm or less, changes in color are unlikely to occur.

Preferred laminate structures of the sealing resin sheet include, for example, [colored adhesive layer (non-diffusion functional layer)/non-colored adhesive layer (non-diffusion functional layer)/base film], [colored adhesive layer (non-diffusion functional layer)/non-colored adhesive layer (diffusion functional layer)/base film], [non-colored adhesive layer (diffusion functional layer)/colored adhesive layer (non-diffusion functional layer)/non-colored adhesive layer (non-diffusion functional layer)/base film], [colored adhesive layer (diffusion functional layer)/non-colored adhesive layer (non-diffusion functional layer)/base film] (all in order from the optical semiconductor element side), etc.

Figures 2 and 3 show other embodiments of the sheet for encapsulating optical semiconductor elements of the present invention. The sheet for encapsulating optical semiconductor elements 1 shown in Figure 2 is an embodiment in which a non-colored adhesive layer 31, which is a diffusion functional layer, is provided on the surface of the colored adhesive layer 4 of the sheet for encapsulating optical semiconductor elements shown in Figure 1. The sheet for encapsulating optical semiconductor elements 1 shown in Figure 3 is an embodiment in which the colored adhesive layer 4 of the sheet for encapsulating optical semiconductor elements shown in Figure 1 is a colored adhesive layer 41, which is a diffusion functional layer.

[Release liner]
The release-treated surface of a release liner may be attached to the adhesive surface of the optical semiconductor element encapsulation sheet. The release liner is used as a protective material for the optical semiconductor element encapsulation sheet and is peeled off when encapsulating the optical semiconductor element. The release liner is not necessarily provided.

The release liner is an element for covering and protecting the surface of the optical semiconductor element encapsulation sheet, and is peeled off from the sheet when the optical semiconductor element encapsulation sheet is attached to a substrate on which an optical semiconductor element is disposed.

Examples of the release liner include polyethylene terephthalate (PET) film, polyethylene film, polypropylene film, plastic films and papers whose surfaces are coated with a release agent such as a fluorine-based release agent or a long-chain alkyl acrylate-based release agent.

The thickness of the release liner is, for example, 10 to 200 μm, preferably 15 to 150 μm, and more preferably 20 to 100 μm. If the thickness is 10 μm or more, the release liner is less likely to break due to cuts during processing. If the thickness is 200 μm or less, the release liner is more easily peeled off from the optical semiconductor element encapsulation sheet during use.

[Method of manufacturing the sheet for encapsulating optical semiconductor elements]
An embodiment of the method for producing a sheet for encapsulating an optical semiconductor element of the present invention will be described. For example, the sheet for encapsulating an optical semiconductor element 1 shown in Fig. 1 is prepared by separately preparing a colored adhesive layer 4 and a non-colored adhesive layer 3, each of which is sandwiched between the release-treated surfaces of two release liners. One of the release liners bonded to the colored adhesive layer 4 is a release liner 5.

Next, one of the release liners attached to the non-colored adhesive layer 3 is peeled off to expose the surface of the non-colored adhesive layer 3, and the exposed surface is attached to the base film 2. Then, one of the release liners attached to the colored adhesive layer 4 is peeled off, and the release liner on the surface of the non-colored adhesive layer 3 is peeled off to expose the surface of the non-colored adhesive layer 3, and the exposed surface of the colored adhesive layer 4 is attached to the surface. The lamination of the various layers can be performed using a known roller or laminator. In this way, the sheet 1 for encapsulating optical semiconductor elements shown in FIG. 1 can be produced, in which the non-colored adhesive layer 3, the colored adhesive layer 4, and the release liner 5 are laminated in this order on the base film 2.

[Optical semiconductor device]
An optical semiconductor device such as a display can be produced using the sheet for encapsulating an optical semiconductor element of the present invention. The display produced using the sheet for encapsulating an optical semiconductor element of the present invention comprises a substrate, an optical semiconductor element arranged on the substrate, and the sheet for encapsulating an optical semiconductor element of the present invention or a cured product obtained by curing the sheet, which encapsulates the optical semiconductor element. The cured product is a cured product obtained by curing the radiation-curable pressure-sensitive adhesive layer by irradiation when the sheet for encapsulating an optical semiconductor element of the present invention comprises a radiation-curable pressure-sensitive adhesive layer.

Examples of the optical semiconductor elements include light-emitting diodes (LEDs), such as blue light-emitting diodes, green light-emitting diodes, red light-emitting diodes, and ultraviolet light-emitting diodes.

In the above optical semiconductor device, the optical semiconductor element encapsulation sheet of the present invention has excellent conformability to the unevenness when the optical semiconductor elements are convex portions and the gaps between multiple optical semiconductor elements are concave portions, and has excellent conformability and embeddability of the optical semiconductor elements, so it is preferable to encapsulate multiple optical semiconductor elements collectively.

It is preferable that the height of the optical semiconductor element on the substrate (the height from the substrate surface to the end of the optical semiconductor element on the front side) is 500 μm or less. If the height is 500 μm or less, the adhesive layer will have better conformability to the uneven shape.

Figure 4 shows one embodiment of an optical semiconductor device using the optical semiconductor element encapsulation sheet 1 shown in Figure 1. The optical semiconductor device 10 shown in Figure 4 includes a substrate 6, a plurality of optical semiconductor elements 7 arranged on one side of the substrate 6, an encapsulating resin layer 8 that encapsulates the optical semiconductor elements 7, and a base film 2 laminated on the encapsulating resin layer 8. The plurality of optical semiconductor elements 7 are encapsulated together in the encapsulating resin layer 8. The encapsulating resin layer 8 is formed by laminating a colored adhesive layer 81 and a non-colored adhesive layer 82. The colored adhesive layer 81 has one interface that follows the uneven shape formed by the plurality of optical semiconductor elements 7 and adheres closely to the optical semiconductor elements 7 and the substrate 6, embedding the optical semiconductor elements 7, and the other interface is flat. In addition, both interfaces of the non-colored adhesive layer 82 are flat.

The encapsulating resin layer 8 is formed by the colored adhesive layer 4 and the non-colored adhesive layer 3. Specifically, when the laminate of the colored adhesive layer 4 and the non-colored adhesive layer 3 in the sheet 1 for encapsulating optical semiconductor elements does not have a radiation-curable adhesive layer, the laminate becomes the encapsulating resin layer 8 in the optical semiconductor device 10. On the other hand, when the colored adhesive layer 4 and the non-colored adhesive layer 3 in the sheet 1 for encapsulating optical semiconductor elements have a radiation-curable adhesive layer, for example, when the colored adhesive layer 4 is a radiation-curable adhesive layer, the colored adhesive layer 4 is cured to form the colored adhesive layer 81, which becomes the encapsulating resin layer 8.

In the optical semiconductor device 10 shown in FIG. 4, the optical semiconductor element 7 is completely embedded and sealed in the colored adhesive layer 81, and is indirectly sealed by the non-colored adhesive layer 82. That is, the optical semiconductor element 7 is sealed by the sealing resin layer 8 consisting of a laminate of the colored adhesive layer 81 and the non-colored adhesive layer 82. The optical semiconductor device is not limited to this embodiment, and may be, for example, as shown in FIG. 5, in which the optical semiconductor element 7 is completely embedded and sealed in the colored adhesive layer 81 and the non-colored adhesive layer 82.

The optical semiconductor device may be a tiled arrangement of individual optical semiconductor devices. In other words, the optical semiconductor device may be a tiled arrangement of multiple optical semiconductor devices in a planar direction.

The display body preferably includes a self-luminous display device. The self-luminous display device can be combined with a display panel as necessary to form a display body that is an image display device. In this case, the optical semiconductor element is an LED element. Examples of the self-luminous display device include an LED display, a backlight, and an organic electroluminescence (organic EL) display device. The backlight is preferably a backlight that is directly under the entire surface. The backlight includes, for example, a laminate that includes the substrate and a plurality of optical semiconductor elements arranged on the substrate as at least a part of its components. For example, in the self-luminous display device, a metal wiring layer is laminated on the substrate for sending a light emission control signal to each LED element. The LED elements that emit light of each color, red (R), green (G), and blue (B), are alternately arranged on the substrate via a metal wiring layer. The metal wiring layer is formed of a metal such as copper, and the light emission degree of each LED element is adjusted to display each color.

The optical semiconductor element encapsulation sheet of the present invention can be used in optical semiconductor devices that are folded when used, such as optical semiconductor devices having a foldable image display device (flexible display) (particularly, a foldable image display device (foldable display)). Specifically, it can be used in foldable backlights and foldable self-luminous display devices.

The optical semiconductor element encapsulation sheet of the present invention has excellent conformability and embeddability for optical semiconductor elements, and can therefore be preferably used when the optical semiconductor device is a mini LED display device or a micro LED display device.

The sheet for encapsulating optical semiconductor elements of the present invention is resistant to changes in the color of the light emitted by the optical semiconductor elements even when the sheet is subjected to an external impact while encapsulating the optical semiconductor elements.

[Method of Manufacturing Optical Semiconductor Device]
The optical semiconductor device can be produced, for example, by laminating the sheet for encapsulating an optical semiconductor element of the present invention to a substrate on which an optical semiconductor element is arranged, and encapsulating the optical semiconductor element with a pressure-sensitive adhesive layer including a colored pressure-sensitive adhesive layer.

(Sealing process)
In the method for manufacturing an optical semiconductor device using the optical semiconductor element encapsulation sheet, the optical semiconductor element encapsulation sheet is attached to a substrate on which an optical semiconductor element is arranged, and the optical semiconductor element is encapsulated by a pressure-sensitive adhesive layer. In the encapsulation step, specifically, the release liner is first peeled off from the optical semiconductor element encapsulation sheet to expose the adhesive surface. Then, the adhesive surface of the optical semiconductor element encapsulation sheet is attached to the substrate surface on which the optical semiconductor element is arranged of a laminate (optical member, etc.) including a substrate and an optical semiconductor element (preferably a plurality of optical semiconductor elements) arranged on the substrate, and when the laminate includes a plurality of optical semiconductor elements, the adhesive layer is further arranged to fill the gaps between the plurality of optical semiconductor elements, and the plurality of optical semiconductor elements are encapsulated together. Specifically, the colored adhesive layer 4 exposed by peeling off the release liner 5 from the optical semiconductor element encapsulation sheet 1 shown in FIG. 1 is arranged so as to face the surface of the substrate 6 on which the optical semiconductor element 7 is arranged, and the optical semiconductor element encapsulation sheet 1 is attached to the surface of the substrate 6 on which the optical semiconductor element 7 is arranged, and the optical semiconductor element 7 is embedded in the adhesive layer.

The temperature during the lamination is, for example, within the range of room temperature to 110°C. In addition, the pressure may be reduced or pressurized during the lamination. The reduced pressure or pressurization can prevent the formation of voids between the pressure-sensitive adhesive layer and the substrate or the optical semiconductor element. In the sealing step, it is preferable to laminate the optical semiconductor element sealing sheet under reduced pressure and then pressurize it. When reduced pressure is applied, the pressure is, for example, 1 to 100 Pa, and the depressurization time is, for example, 5 to 600 seconds. When pressurized, the pressure is, for example, 0.05 to 0.5 MPa, and the pressurization time is, for example, 5 to 600 seconds.

(Radiation Irradiation Step)
When the pressure-sensitive adhesive layer comprises a radiation-curable pressure-sensitive adhesive layer, the manufacturing method may further comprise a radiation irradiation step of irradiating radiation to a laminate comprising the substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet encapsulating the optical semiconductor element, to cure the radiation-curable pressure-sensitive adhesive layer and form a cured product layer. As described above, examples of the radiation include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. Among these, ultraviolet rays are preferred. The temperature during radiation irradiation is, for example, within the range of room temperature to 100° C., and the irradiation time is, for example, 1 minute to 1 hour.

(Dicing process)
The manufacturing method may further include a dicing step of dicing a laminate including the substrate, the optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet encapsulating the optical semiconductor element. The laminate may be diced after the radiation irradiation step. When the laminate includes a cured material layer in which the radiation-curable adhesive layer is cured by the radiation irradiation, the dicing step involves dicing and removing the cured material layer of the optical semiconductor element encapsulation sheet and the side end of the substrate. This allows the surface of the cured material layer that has been sufficiently cured and has reduced adhesion to be exposed on the side. The dicing can be performed by a known or conventional method, for example, a method using a dicing blade or laser irradiation.

(Tiling process)
The manufacturing method may further include a tiling step of arranging the plurality of optical semiconductor devices obtained in the dicing step so as to be in contact with each other in a planar direction. In the tiling step, the plurality of laminates obtained in the dicing step are tiled so as to be in contact with each other in a planar direction. In this manner, one large display body can be manufactured.

In this manner, an optical semiconductor device can be manufactured. When the colored adhesive layer 4 and the non-colored adhesive layer 3 in the sheet 1 for sealing an optical semiconductor element do not have a radiation-curable adhesive layer, the colored adhesive layer 4 and the non-colored adhesive layer 3 become the encapsulating resin layer 8 in the optical semiconductor device 10. On the other hand, when the colored adhesive layer 4 and the non-colored adhesive layer 3 in the sheet 1 for sealing an optical semiconductor element have a radiation-curable adhesive layer, for example, when the colored adhesive layer 4 is a radiation-curable adhesive layer, the colored adhesive layer 4 is cured to form a colored adhesive layer 81, which becomes the encapsulating resin layer 8.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

Production Example 1
(Preparation of Non-Colored Adhesive Layer A)
In a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube, 67 parts by mass of butyl acrylate (BA), 14 parts by mass of cyclohexyl acrylate (CHA, trade name "Viscoat #155", manufactured by Osaka Organic Chemical Industry Co., Ltd.), 19 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.09 parts by mass of a photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF Corporation), and 0.09 parts by mass of a photopolymerization initiator (trade name "Irgacure 651", manufactured by BASF Corporation) were added as monomer components, and then nitrogen gas was flowed and nitrogen substitution was performed for about 1 hour while stirring. Thereafter, polymerization was performed by irradiating ultraviolet light at 5 mW/cm ² , and the reaction rate was adjusted to 5 to 15%, to obtain an acrylic prepolymer solution A. A non-colored adhesive composition was prepared by adding 9 parts by mass of 2-hydroxyethyl acrylate (HEA), 8 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.12 parts by mass of dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Shin-Nakamura Industrial Chemical Co., Ltd.) as a polyfunctional monomer, and 0.35 parts by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) to the acrylic prepolymer solution A (total amount of prepolymers is 100 parts by mass).

The non-colored adhesive composition was applied onto the release-treated surface of a release liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side subjected to release treatment, thickness 38 μm) to form a resin composition layer, and then the release-treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) was also bonded onto the resin composition layer. Next, ultraviolet rays with an illuminance of 5 mW/ ^cm2 were irradiated using a black light until the accumulated light amount reached 3600 mJ/ ^cm2 to perform polymerization, thereby producing a non-colored adhesive layer A (thickness 100 μm).

Production Example 2
(Preparation of Non-Colored Adhesive Layer B)
A non-colored adhesive layer B was prepared in the same manner as in Production Example 1, except that the thickness of the non-colored adhesive layer was 200 μm.

Production Example 3
(Preparation of Colored Adhesive Layer A)
To the acrylic prepolymer solution A (total amount of prepolymer is 100 parts by mass) prepared in Production Example 1, 9 parts by mass of 2-hydroxyethyl acrylate (HEA), 8 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by mass of dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Shin-Nakamura Industrial Chemical Co., Ltd.) as a polyfunctional monomer, 0.35 parts by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.), 0.3 parts by mass of a photopolymerization initiator (product name "Irgacure 651", manufactured by BASF), and 4.31 parts by mass of a black pigment dispersion (product name "9256BLACK", manufactured by TOKUSHIKI CORPORATION) were added to prepare a colored adhesive composition.

The colored adhesive composition was applied onto the release-treated surface of a release liner (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side subjected to release treatment, thickness 38 μm) to form a colored adhesive composition layer, and then the release-treated surface of a release liner (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) was also bonded onto the colored adhesive composition layer. Next, ultraviolet rays with an illuminance of 5 mW/cm ² were irradiated by a black light until the accumulated light amount reached 3600 mJ/cm ² to perform polymerization, thereby preparing a colored adhesive layer A (thickness 50 μm). The total light transmittance of the colored adhesive layer A was 10%.

Production Example 4
(Preparation of Colored Adhesive Layer B)
To the acrylic prepolymer solution A (total amount of prepolymer is 100 parts by mass) prepared in Production Example 1, 9 parts by mass of 2-hydroxyethyl acrylate (HEA), 8 parts by mass of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by mass of dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Shin-Nakamura Industrial Chemical Co., Ltd.) as a polyfunctional monomer, 0.35 parts by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.), 0.3 parts by mass of a photopolymerization initiator (product name "Irgacure 651", manufactured by BASF), and 2.76 parts by mass of a black pigment dispersion (product name "9256BLACK", manufactured by TOKUSHIKI CORPORATION) were added to prepare a colored adhesive composition.

The colored adhesive composition was applied onto the release-treated surface of a release liner (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side subjected to release treatment, thickness 38 μm) to form a colored adhesive composition layer, and then the release-treated surface of a release liner (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) was also bonded onto the colored adhesive composition layer. Next, ultraviolet rays with an illuminance of 5 mW/cm ² were irradiated by a black light until the accumulated light amount reached 3600 mJ/cm ² to perform polymerization, thereby preparing a colored adhesive layer B (thickness 50 μm). The total light transmittance of the colored adhesive layer B was 20%.

Production Example 5
(Preparation of PC film A)
Polycarbonate resin (product name "DURABIO", manufactured by Mitsubishi Chemical Corporation) was vacuum-dried at 80°C for 5 hours, and then a polycarbonate (PC) film A having a thickness of 180 μm was produced using a film-forming device equipped with a single-screw extruder (manufactured by Shibaura Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 300 mm, set temperature: 250°C), a chill roll (set temperature: 120 to 130°C) and a winder.

Production Example 6
(Preparation of PC film B)
PC film B was produced in the same manner as in Production Example 5, except that the thickness was 70 μm.

Production Example 7
(Preparation of PC film C)
A PC film C was produced in the same manner as in Production Example 5, except that the thickness was 90 μm.

Production Example 8
(Preparation of acrylic resin film)
An adhesive composition with a solids concentration of 20 mass% was prepared by adding and mixing 85 parts by mass of an acrylic resin (trade name "TEISAN RESIN SG-80H", manufactured by Nagase ChemteX Corporation), 25 parts by mass of an inorganic filler (trade name "YA010C", manufactured by Admatechs Co., Ltd.), 0.27 parts by mass of a curing agent (trade name "Curesol 2MZ", manufactured by Shikoku Kasei Corporation), and 0.27 parts by mass of an antioxidant (trade name "ADK STAB PEP-8", manufactured by ADEKA Corporation) to methyl ethyl ketone.
Next, the adhesive composition was applied onto the release-treated surface of a release liner (trade name "Diafoil MRA", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side subjected to release treatment, thickness 38 μm) to form a resin composition layer. Next, this composition layer was heated and dried at 130 ° C for 2 minutes to prepare a transparent adhesive sheet with a thickness of 20 μm on a PET film. Then, the release-treated surface side of a release liner (trade name "Diafoil MRF", manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with one side subjected to release treatment, thickness 25 μm) was attached to the transparent adhesive sheet at a temperature condition of 60 ° C to prepare a transparent adhesive sheet with a release agent. For each of the two transparent adhesive sheets with a release agent, one of the release liners was peeled off, and the adhesive surfaces were attached to each other at a temperature condition of 80 ° C. This process was carried out nine more times to prepare an adhesive sheet with a release agent with a thickness of 200 μm. This adhesive sheet with release agent was heated at 120° C. for 3 hours to produce an acrylic resin film layer.

Example 1
(Preparation of Sheet for Encapsulating Optical Semiconductor Elements)
The release liner (product name "MRE38") was peeled off from the non-colored adhesive layer A obtained in Production Example 1 to expose the adhesive surface. The exposed surface of the non-colored adhesive layer A was attached to the PC film A produced in Production Example 5 to form a non-colored adhesive layer A on the base film.
Next, the release liner (product name "MRF38") was peeled off from the surface of the non-colored adhesive layer A to expose the adhesive surface. The adhesive surface exposed by peeling off the release liner (product name "MRE38") from the colored adhesive layer B obtained in Production Example 4 was attached to the exposed surface of the non-colored adhesive layer A to form a colored adhesive layer B on the non-colored adhesive layer A.
The lamination was performed at room temperature (25° C.) using a hand roller so as not to trap air bubbles. In this manner, a sheet for encapsulating optical semiconductor elements comprising [release liner/colored adhesive layer B (50 μm)/non-colored adhesive layer A (100 μm)/PC film A (180 μm)] was obtained.

Example 2
A sheet for encapsulating optical semiconductor elements was obtained in the same manner as in Example 1, except that the colored adhesive layer A prepared in Production Example 3 was used instead of the colored adhesive layer B, and the sheet consisted of [release liner/colored adhesive layer A (50 μm)/non-colored adhesive layer A (100 μm)/PC film A (180 μm)].

Example 3
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer B (50 μm)/non-colored adhesive layer B (200 μm)/PC film A (180 μm)] was obtained in the same manner as in Example 1, except that the non-colored adhesive layer B prepared in Production Example 2 was used instead of the non-colored adhesive layer A.

Example 4
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer A (50 μm)/non-colored adhesive layer B (200 μm)/PC film A (180 μm)] was obtained in the same manner as in Example 1, except that the colored adhesive layer A prepared in Production Example 3 was used instead of the colored adhesive layer B, and the non-colored adhesive layer B prepared in Production Example 2 was used instead of the non-colored adhesive layer A.

Example 5
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer A (50 μm)/non-colored adhesive layer A (100 μm)/PET film (188 μm)] was obtained in the same manner as in Example 1, except that the colored adhesive layer A prepared in Production Example 3 was used instead of the colored adhesive layer B, and a PET film (product name "Lumirror #188-U34", manufactured by Toray Industries, Inc.) was used instead of the PC film A.

Comparative Example 1
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer B (50 μm)/non-colored adhesive layer B (200 μm)/PC film B (70 μm)] was obtained in the same manner as in Example 1, except that the non-colored adhesive layer B prepared in Production Example 2 was used instead of the non-colored adhesive layer A, and the PC film B prepared in Production Example 6 was used instead of the PC film A.

Comparative Example 2
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer B (50 μm)/non-colored adhesive layer B (200 μm)/PC film C (90 μm)] was obtained in the same manner as in Example 1, except that the non-colored adhesive layer B prepared in Production Example 2 was used instead of the non-colored adhesive layer A, and the PC film C prepared in Production Example 7 was used instead of the PC film A.

Comparative Example 3
A sheet for encapsulating optical semiconductor elements consisting of [release liner/colored adhesive layer B (50 μm)/non-colored adhesive layer A (100 μm)/acrylic resin film (200 μm)] was obtained in the same manner as in Example 1, except that the acrylic resin film prepared in Production Example 8 was used instead of PC film A.

<Evaluation>
The layers produced in each Production Example and the sheets for encapsulating optical semiconductor elements obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

(1) Measurement of storage modulus of base film The base film used in each of the examples and comparative examples was cut into a strip shape with a length of 40 mm and a width of 10 mm using a cutter knife. Next, the storage modulus was measured at 0 to 100°C using a solid viscoelasticity measuring device (product name "RSA-G2", manufactured by TA Instruments). The measurement conditions were a frequency of 1 Hz, a temperature rise rate of 10°C/min, and a chuck distance of 20.0 mm. The value of the storage modulus at 25°C was then read and used as the storage modulus.

(2) (Calculation of E × (h-λ) ³ )
Based on the elastic modulus measured in the above-mentioned storage elastic modulus measurement and the size of the optical semiconductor element encapsulation sheet, E×(h-λ) ³ [Formula 1] (E: elastic modulus of the film layer at 25° C. (MPa), h: thickness of the base film (mm), λ: distance from the upper edge of the base film to the neutral axis (mm)) of the base film used in each Example and Comparative Example was calculated. Note that, for example, in Example 1, E=2700 (MPa), h=0.180 (mm), and λ=0.090 (mm) were used as the respective values in [Formula 1].

(3) Judgment of color change From the semiconductor element encapsulation sheet prepared in the examples and comparative examples, the release liner on the surface of the colored adhesive layer was peeled off, and the exposed adhesive layer was attached to a glass plate (slide glass, product name "S-9112", manufactured by Matsunami Glass Industry Co., Ltd.) with a hand roller. Thereafter, a pencil scratch hardness tester (product name "MJ-PHT", manufactured by Sato Shoji Co., Ltd.) was used on the surface of the base film, and a test was performed using a pencil (product name "Uni", manufactured by Mitsubishi Pencil Co., Ltd., pencil hardness 3H) with a load of 500 g in accordance with the usage environment temperature and usage environment humidity in accordance with JIS-K5600, and the color change was visually evaluated. The case where no color change was observed was marked ◯, the case where a slight color change was observed was marked △, and the case where a noticeable color change was confirmed was marked ×.

(4) Observation of maximum dent amount of colored adhesive layer A sheet was peeled off from the sample glass used to judge the above color change, and the cross section of the part where a load was applied with the pencil scratch hardness tester was exposed with a trimming cutter. The exposed part was observed with a microscope (product name "VK-X200", manufactured by Keyence Corporation) to measure the maximum dent amount of the colored adhesive layer.

In the optical semiconductor element encapsulation sheets of the Examples, the value of E×(h-λ) ³ was 1.0 or more, and it was confirmed that there was no change in color when an external impact was applied. On the other hand, in the optical semiconductor element encapsulation sheets of the Comparative Examples, in which the value of E×(h-λ) ³ was less than 1.0, it was confirmed that the dent in the colored pressure-sensitive adhesive layer was larger and the color changed compared to the optical semiconductor element encapsulation sheets of the Examples.

Variations of the invention according to the present invention will be described below.
[Appendix 1]
A sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, comprising:
The sheet includes a base film and a colored adhesive layer laminated on the base film,
The sheet for encapsulating optical semiconductor elements, wherein the base film satisfies E×(h−λ) 3 ≧1.0, where E (MPa) is the storage modulus of the base film at 25° ^C. , h (mm) is the thickness of the base film, and λ (mm) is the distance from the upper edge of the base film to the neutral axis.
[Appendix 2]
2. The sheet for encapsulating an optical semiconductor element according to claim 1, further comprising a non-colored pressure-sensitive adhesive layer between the base film and the colored pressure-sensitive adhesive layer.
[Appendix 3]
3. The sheet for encapsulating an optical semiconductor element according to claim 1 or 2, wherein the thickness of the base film is 150 to 500 μm and the storage modulus of the base film is 1.8 to 10 GPa.
[Appendix 4]
3. The sheet for encapsulating an optical semiconductor element according to claim 2, wherein the non-colored pressure-sensitive adhesive layer has a thickness of 100 to 200 μm.
[Appendix 5]
5. The sheet for encapsulating an optical semiconductor element according to any one of claims 1 to 4, wherein the colored pressure-sensitive adhesive layer has a total light transmittance of 5 to 99%.
[Appendix 6]
A display comprising: a substrate; an optical semiconductor element disposed on the substrate; and the sheet for encapsulating an optical semiconductor element or a cured product thereof according to any one of appendices 1 to 5, which encapsulates the optical semiconductor element.
[Appendix 7]
7. The display according to claim 6, comprising a self-luminous display device.
[Appendix 8]
7. The display according to claim 6, which is an image display device.

Reference Signs List 1: Sheet for sealing optical semiconductor element 2: Base film 3: Non-colored adhesive layer 4: Colored adhesive layer 5: Release liner 6: Substrate 7: Optical semiconductor element 8: Sealing resin layer 81: Colored adhesive layer 82: Non-colored adhesive layer 10: Optical semiconductor device

Claims (8)

A sheet for encapsulating one or more optical semiconductor elements disposed on a substrate, comprising:
The sheet includes a base film and a colored adhesive layer laminated on the base film,
The sheet for encapsulating optical semiconductor elements, wherein the base film satisfies E×(h−λ) 3 ≧1.0, where E (MPa) is the storage modulus of the base film at 25° ^C. , h (mm) is the thickness of the base film, and λ (mm) is the distance from the upper edge of the base film to the neutral axis. The sheet for encapsulating optical semiconductor elements according to claim 1, further comprising a non-colored adhesive layer between the base film and the colored adhesive layer. The sheet for encapsulating optical semiconductor elements according to claim 1 or 2, wherein the thickness of the substrate film is 150 to 500 μm, and the storage modulus of the substrate film is 1.8 to 10 GPa. The sheet for encapsulating optical semiconductor elements according to claim 2, wherein the thickness of the non-colored adhesive layer is 100 to 200 μm. The sheet for encapsulating optical semiconductor elements according to claim 1 or 2, wherein the total light transmittance of the colored adhesive layer is 5 to 99%. A display comprising a substrate, an optical semiconductor element disposed on the substrate, and the optical semiconductor element encapsulation sheet according to claim 1 or 2, or a cured product thereof, which encapsulates the optical semiconductor element. The display according to claim 6, which is equipped with a self-luminous display device. The display according to claim 6, which is an image display device.

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