Sealing sheet and display

Abstract

The present invention provides: a sealing sheet which is excellent in terms of embeddability and seamless properties in cases where an optical semiconductor element is sealed therewith, and which is excellent in terms of embeddability and seamless properties even in cases where the sealing sheet is applied to a display that uses a micro LED as a light source; and a display. Provided is a sealing sheet (1) for sealing an optical semiconductor element (5), the sealing sheet (1) including a protective film and a resin composition layer (2) arranged in this order. The resin composition layer (2) contains 5.3-48.2 parts by mass of metal oxide particles (B) relative to a total of 100 parts by mass of a resin (A), a monomer, and an oligomer. The number average primary particle diameter of the metal oxide particles (B) is 5-50 nm, and the refractive index of the resin composition layer (2) is 1.45-1.65.

Description

Encapsulating sheets and displays

[0001] The present disclosure relates to an encapsulating sheet, and more particularly to an encapsulating sheet including a resin composition layer for encapsulating an optical semiconductor element used in various products such as electronic devices and displays, and a display equipped with the resin composition layer.

[0002] In recent years, development of displays using various light-emitting elements has been actively pursued in order to further improve display performance. Specifically, various display specifications have been researched, including backlit displays using liquid crystals or quantum dots, displays using self-emitting elements such as mini / micro LEDs and organic electroluminescence (EL), plasma displays, and electrophoretic displays. These displays are being considered for a wide range of applications, from large displays such as signage and televisions to small displays such as tablets, personal computers, smartphones, and wearable devices. Development of LED-based displays in particular is progressing rapidly, and Patent Document 1 describes a thermosetting resin composition for encapsulating LED elements. Patent Document 2 also discloses a transparent thermally conductive composition containing a resin and a filler that can be used as an encapsulant for optical semiconductors. The filler essentially contains a thermally conductive filler with an average particle size of 1 to 100 μm and a thermal conductivity of 2 W / m·K or greater, and a high-refractive-index filler with an average particle size of 1 to 100 nm and a refractive index of 1.8 or greater. MicroLED displays are attracting the most attention as a next-generation display technology.

[0003] International Publication No. 2021 / 200035

[0004] Patent Document 1 describes an optical semiconductor element encapsulation sheet that is easy to handle and can encapsulate optical semiconductor elements using a simple process in a short time. However, as optical semiconductor elements have become increasingly miniaturized in recent years, the spacing between optical semiconductor elements has become narrower, making it difficult for the sheet-shaped resin composition described in Patent Document 1 to conform to micro-sized optical semiconductor elements and fill the gaps (embeddability). When there is a gap between the optical semiconductor element and the encapsulating resin composition, particularly in an LED display module, brightness decreases due to light refraction in the gap. Furthermore, micro LED displays are constructed by connecting small micro LED display modules, each approximately 9 to 10 inches, vertically and horizontally in a tiled pattern to create a large screen. In this case, a problem has arisen in that the joints between the modules are noticeable when the display is viewed from a close distance (seamlessness). In addition to high brightness, an encapsulating sheet with excellent embeddability and seamlessness is needed to create a display with inconspicuous joints.

[0005] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide an encapsulating sheet that has excellent embeddability for optical semiconductor elements. Another object of the present disclosure is to provide an encapsulating sheet and a display having a resin composition layer that have excellent embeddability, seamlessness, and visibility, particularly when applied to a display that uses a micro LED element as a light source. Another object of the present disclosure is to provide an encapsulating sheet that has excellent adhesion to a substrate from the viewpoint of simplifying the manufacturing process of a micro LED display.

[0006] As a result of intensive studies, the present inventors have found that the above problems can be solved by the encapsulating sheets shown below, and have completed the present inventions [1] to [9] below.

[0007] [1]: An encapsulating sheet for encapsulating an optical semiconductor element, the encapsulating sheet comprising a protective film and a resin composition layer arranged in this order, the resin composition layer containing a resin (A) and metal oxide particles (B), the number-average primary particle diameter of the metal oxide particles (B) being 5 to 50 nm, and the refractive index of the resin composition layer being 1.45 to 1.65. [2]: The encapsulating sheet according to [1], wherein the metal constituting the metal oxide particles (B) includes at least one metal selected from the group consisting of Ti, Al, and Zr. [3]: The encapsulating sheet according to [1] or [2], wherein the resin (A) includes at least one metal selected from the group consisting of a (meth)acrylic resin (a) and a urethane resin (b). [4]: ​​The resin composition layer has a haze of 12% or less and a total light transmittance of 80% or more, and the CIE L ＊ a ＊ b ＊The encapsulating sheet according to any one of [1] to [3], wherein the chroma C* calculated from a color space is 0 to 10. [5]: The encapsulating sheet according to any one of [1] to [4], wherein the resin composition layer has a thickness Ta of 1 to 100 μm and the protective film has a thickness Tb of 10 to 188 μm. [6]: The encapsulating sheet according to any one of [1] to [5], wherein the protective film and the resin composition layer are directly laminated together, and wherein a ratio of a root-mean-square height Sq defined in ISO 25178 at a surface of the protective film in contact with the resin composition layer to the thickness Ta of the resin composition layer is 0.01 to 30%. [7]: The encapsulating sheet according to any one of [1] to [6], wherein a peak top intensity (tan δ peak intensity) of a loss tangent obtained by dynamic viscoelasticity measurement of the resin composition layer in a temperature range of −50 to 80° C. is 0.6 to 2.2. [8]: The encapsulating sheet according to any one of [1] to [7], wherein the optical semiconductor element is a micro LED. [9]: The encapsulating sheet according to any one of [1] to [8], wherein the resin composition layer contains 5.3 to 48.2 parts by mass of a metal oxide (B) relative to 100 parts by mass of the total of the resin (A), the monomer, and the oligomer.

[10] : A display having an encapsulating layer containing a resin (A) and metal oxide particles (B), wherein the metal oxide particles (B) have a number-average primary particle diameter of 5 to 50 nm and a refractive index of 1.45 to 1.65.

[11] : The display according to

[10] , wherein the metal oxide particles (B) are contained in an amount of 5.3 to 48.2 parts by mass relative to 100 parts by mass of the total of the resin (A), the monomer, and the oligomer.

[0008] According to the present disclosure, it has become possible to provide a display having an encapsulating sheet and a resin composition layer that are excellent in embeddability of optical semiconductor elements, and that are excellent in embeddability, seamlessness, adhesion, and visibility, particularly when applied to a display that uses a micro LED element as a light source.

[0009] 1 is a schematic cross-sectional view showing an example of a layered structure of an encapsulating sheet; 2 is a schematic cross-sectional view showing another example of a layered structure of an encapsulating sheet; 3 is a schematic cross-sectional view showing a process of forming an encapsulating layer on a substrate having an optical semiconductor element; 4 is a cross-sectional view showing an example of a test substrate simulating a substrate of a micro LED.

[0010] The present disclosure will be described in detail below. Note that the embodiment described below is an example of the present disclosure. The present disclosure is not limited to the following embodiment, and includes modifications implemented within the scope that does not change the gist of the present disclosure. In this specification, a numerical range specified using "to" includes the numerical values ​​written before and after "to" as the lower and upper limit ranges. (Meth)acrylic acid refers to acrylic acid and methacrylic acid. Furthermore, unless otherwise noted, the various components appearing in this specification may each be used independently alone or in combination of two or more types.

[0011] 1A , the encapsulating sheet of the present disclosure has a resin composition layer 2 and a protective film 3 arranged in this order. A plurality of resin composition layers 2 can be provided. It is preferable that the protective film 3 is directly laminated on the resin composition layer.

[0012] The protective film is a support for the resin composition layer and provides handleability to the encapsulating sheet. The protective film is preferably used in such a manner that it is peeled off after forming an encapsulating layer around the optical semiconductor element using the resin composition layer.

[0013] In the above-described usage form, the protective film is not particularly limited, but examples thereof include polyester films such as polybutylene terephthalate and polyethylene naphthalate, polyolefin films such as polypropylene and polyethylene, and plastic films such as polyvinyl chloride films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, and cycloolefin films. The plastic film preferably has peelability, and more preferably has a release layer formed by coating the plastic film with a release agent such as silicone resin, alkyd resin, fluororesin, or melamine resin. The plastic film may have a functional layer in addition to the release layer. Specific examples of the functional layer include an antistatic layer, and examples of a laminated structure include antistatic layer / plastic film substrate / release layer and plastic film substrate / antistatic layer / release layer.

[0014] The thickness Tb of the protective film (thickness including the release layer if a release layer is provided) is not particularly limited, but is preferably 10 to 188 μm, more preferably 10 to 100 μm, and even more preferably 10 to 75 μm. By setting the thickness to 10 to 188 μm, the transfer of the waviness of the protective film to the resin composition layer is suppressed, resulting in good embeddability and adhesion. The thickness Tb can be measured, for example, by the method described in the Examples below.

[0015] When the protective film is directly laminated to a resin composition layer, the ratio of the root mean square height (Sq) of the surface roughness according to ISO 25178 to the thickness (Ta) of the resin composition layer on the surface of the protective film in contact with the resin composition layer is preferably 0.01 to 30%, more preferably 0.1 to 20%, and even more preferably 0.15 to 12%. By adjusting the ratio to 0.01 to 30%, the surface roughness transferred to the resin composition layer is controlled, and the resin composition layer is sufficiently smoothed in the pressing process described below, resulting in good seamlessness and adhesion. The root mean square height (Sq) can be measured, for example, by the method described in the Examples described below. The root mean square height (Sq) value is preferably 0.01 to 2 μm, more preferably 0.04 to 1.5 μm, and even more preferably 0.1 to 1.5 μm.

[0016] The root mean square height Sq can be adjusted by a release treatment of the release layer surface of the protective film. For example, it can be adjusted by the type of release agent, the amount of release agent applied, and the application method of the release agent. To increase the root mean square height Sq, it is effective to reduce the amount of release agent applied, accelerate drying after application of the release agent, or add a filler to the release agent. Conversely, to decrease the root mean square height Sq, it is possible to adjust the same in the opposite way. In addition, a method of transferring unevenness using a film or carrier material having a predetermined root mean square height Sq can also be applied.

[0017] As shown in FIG. 1B , the encapsulating sheet of the present disclosure preferably has a three-layer structure of protective film 3 / resin composition layer 2 / release liner 4. A release liner is a film in which a release layer is laminated on a substrate, and the substrate and release agent described for the protective film can be used. The release liner and the protective film may be the same, but from the perspective of handling, it is preferable to design the release liner 4 so that its release strength is smaller than that of the protective film. The release strength between the protective film 3 and the release liner 4 can be adjusted by a release treatment on the surface of each release liner to be attached to the resin composition layer. For example, this can be adjusted by the type of release agent, the amount of release agent applied, and the surface roughness of the release layer. To reduce the release strength, treatments such as increasing the amount of release agent applied are effective, and to increase the release strength, the opposite can be done. The thickness Tc of the release liner 4 is preferably in the range of 10 to 150 μm, and preferably satisfies the relationship Tc<Tb. When using the three-layer structure shown in FIG. 1B , a preferred manufacturing method involves forming the resin composition layer 2 on the protective film 3 and then laminating the release liner 4.

[0018] After producing the encapsulating sheet, or while producing the encapsulating sheet, the encapsulating sheet is wound around a core in a roll shape to obtain an encapsulating sheet roll. The winding length can be designed depending on the application. From the viewpoint of increasing productivity, it is preferably 50 m or more, and more preferably 100 m or more. From the viewpoint of production yield, the winding length is preferably 10,000 m or less. When the encapsulating sheet is in the form of a roll, it is preferable to provide a release liner on the outer side of the winding.

[0019] The encapsulating sheet of the present disclosure is used to encapsulate an optical semiconductor element. The resin composition layer is preferably directly adhered to the optical semiconductor element for encapsulation. The optical semiconductor element is preferably disposed on a substrate made of, but not limited to, acrylic, urethane, polycarbonate, epoxy, polyimide, glass, paper, cloth, aluminum, ceramic, or polyethylene terephthalate, and has an electrode portion. A single optical semiconductor element or multiple optical semiconductor elements may be disposed. When multiple optical semiconductor elements are disposed, a light-shielding layer may be disposed between the optical semiconductor element portions.

[0020] Because the resin composition layer has high conformability to uneven surfaces, it is suitable for use in conforming to optical semiconductor elements and filling the spaces between them. By filling the spaces between optical semiconductor elements with the resin composition layer, an encapsulating layer composed of the resin composition layer is formed. The encapsulating layer functions to secure adjacent optical semiconductor elements and prevent them from falling off or becoming misaligned. In particular, because the resin composition layer of the encapsulating sheet of the present disclosure can conform to micro-sized optical semiconductor elements, micro LEDs are more suitable as optical semiconductor elements, and it is even more preferable to use the resin composition layer as an encapsulating layer for a micro LED display panel. Micro LEDs are minute LED elements (chips) with a thickness of 50 μm or 100 μm or less. By mounting multiple micro LEDs (chips) on a substrate with wiring and circuits, a display using multiple optical semiconductor elements as a light source is formed. Micro LEDs include LED elements such as GaAs, GaP, AlGaInP, and InGaN, and operate at a temperature of 25 to 60°C. An example of a process for forming an encapsulating layer is described below with reference to FIG. 2.

[0021] Step (a): Step of placing encapsulant sheet As shown in FIG. 2(a), the resin composition layer 2 of the encapsulant sheet is placed on a substrate 6 having an optical semiconductor element 5 so as to directly cover the optical semiconductor element 5. If the encapsulant sheet has a release liner, the release liner is peeled off to expose the resin composition layer 2, and then the encapsulant sheet is placed as described above. The protective film may be peeled off immediately after placement, or may be peeled off after the pressing step described below. In this specification, the number of optical semiconductor elements is not particularly limited. In display applications, the number of optical semiconductor elements used is determined by the display size and the number of pixels. Furthermore, the emitted color of the optical semiconductor element is not particularly limited, and examples of colors include red, green, and blue. The optical semiconductor element has a thickness of 100 μm or less and an area of ​​40,000 μm in plan view. ２ The thickness is preferably 50 μm or less and the area in plan view is 10,000 μm or less. ２ The following is more preferable: a thickness of 20 μm or less and an area in plan view of 2,500 μm ２The following are more preferred: The spacing between optical semiconductor elements mounted on a substrate is, for example, 10 to 5,000 μm. When a set of red, green, and blue optical semiconductor elements is mounted on a substrate as one pixel, the spacing between pixels is, for example, 10 to 2,000 μm, preferably 20 to 1,800 μm, and more preferably 500 to 1,500 μm. The spacing between optical semiconductor elements within one pixel is, for example, 10 to 200 μm, preferably 10 to 100 μm, and more preferably 20 to 60 μm.

[0022] Step (b): Pressing Step As shown in FIG. 2(b), the resin composition layer 2 is fluidized by pressing and filled around the optical semiconductor element 5 and between the optical semiconductor elements 5. The resin composition layer 2 filled around the optical semiconductor element 5 and between the optical semiconductor elements 5 becomes the encapsulating layer 2'. While the pressing method is not particularly limited, heat pressing and vacuum pressing are preferred. From the viewpoint of the filling property of the resin composition layer, the temperature during pressing is preferably 20 to 200°C, more preferably 30 to 150°C, even more preferably 40 to 130°C, and particularly preferably 60 to 110°C. To improve adhesion to the optical semiconductor element and the adherend, further heat aging may be performed after pressing. The heating temperature is preferably 40 to 250°C, more preferably 80 to 220°C, and even more preferably 100 to 190°C. The heating time is preferably 30 to 300 minutes, more preferably 60 to 240 minutes, and even more preferably 90 to 180 minutes. By using the above heating temperature and heating time, residual stress in the resin composition layer can be removed and the adhesion surface can be smoothed. Heat aging may be carried out after the step (c) described below.

[0023] Step (c): Etching Step In step (c), etching is performed to remove or thin the encapsulation layer on the optical semiconductor element. Removing the encapsulation layer improves the brightness of the optical semiconductor element and ensures visibility during light emission. The thickness of the encapsulation layer after etching is preferably approximately the same as the thickness of the optical semiconductor element, as shown in FIG. 2(c-1), or less than the thickness of the optical semiconductor element, as shown in FIG. 2(c-2). It is acceptable for the encapsulation layer to be substantially removed without being completely removed from the optical semiconductor element, and a small amount of thin film may remain. If sufficient brightness can be ensured, step (c) may be omitted. The etching method is not particularly limited, but preferred examples include wet etching methods such as chemical polishing using chemicals, physical polishing using an abrasive, laser etching, plasma etching using argon plasma or oxygen plasma, and dry etching methods such as ion beam etching. From the perspective of reducing surface irregularities, plasma etching or a combination of wet and dry etching methods is preferred. Furthermore, plasma etching conditions include, for example, using an anisotropic plasma device with CF ４ / O ２ / N ２ Dry etching can be performed using a mixed gas of CF4 and CF5 under the conditions of an output of 1500 to 3000 W and a time of 180 to 600 seconds. ４ The gas supply rate is, for example, 50 to 100 sccm. ２ The gas supply amount is, for example, 500 to 1000 sccm, N ２ The gas supply rate may be set to, for example, 50 to 100 sccm.

[0024] As described above, the sealing layer can be formed from the resin composition layer through steps (a) to (c). Next, the components of the sealing sheet of the present disclosure will be described in detail while citing preferred examples.

[0025] [Resin Composition Layer] The resin composition layer contains a resin (A) and metal oxide particles (B), and preferably further contains a crosslinking agent and / or a polymerization initiator, and may contain other components. Examples of other components include the monomers and oligomers described below. In the present disclosure, the resin (A) is a substance that functions as a binder to bond and fix objects. Specific examples include the function of adhering to and fixing a substrate having an optical semiconductor element or an optical semiconductor element.

[0026] The refractive index of the resin composition layer is 1.45 to 1.65, preferably 1.47 to 1.60, and more preferably 1.49 to 1.55. A refractive index of 1.45 to 1.65 improves seamlessness and visibility. The refractive index can be adjusted by the type and composition of the resin (A) and the type, dispersion state, and content of the metal oxide particles (B). The refractive index can be increased by increasing the content of the aromatic ring structure in the resin (A) or the content of the metal oxide particles (B). If a lower refractive index is desired, the opposite can be adjusted. The content of the metal oxide particles (B) is preferably 5.3 to 48.2 parts by mass per 100 parts by mass of the total of the resin (A), monomer, and oligomer.

[0027] The peak top intensity (tan δ peak intensity) of the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure in the range of -50 to 80 ° C. is the value of the loss tangent (tan δ) when the tan δ curve is maximized. When there are two or more peaks, it refers to the top intensity of the peak at the lowest temperature. The tan δ peak intensity is preferably 0.6 to 2.2, more preferably 0.8 to 2.0, and even more preferably 0.9 to 1.8. By setting the tan δ peak intensity to 0.6 to 2.2, the resin composition layer is better able to absorb the pressure applied during the pressing process, forming a uniform encapsulating layer that conforms to the optical semiconductor element, improving embeddability and adhesion. The tan δ peak intensity of the present disclosure can be adjusted by the type and composition of the resin (A), the type, dispersion state and content of the metal oxide particles (B), and the type and content of the monomer and / or oligomer. When the resin (A) contains a (meth)acrylic resin (a), the tan δ peak intensity can be made higher than when the resin (A) contains a urethane resin (b), but this is not always the case depending on the resin composition. When the resin (A) contains a (meth)acrylic resin (a), the tan δ peak intensity can be lowered by increasing the content of methacrylic acid alkyl ester such as methyl methacrylate, and when it is desired to increase the tan δ peak intensity, the opposite can be adjusted. When the metal oxide particles (B) contain ZrO ２ When it contains TiO ２ However, this is not always the case depending on the dispersion state of the particles. ２ When containing ZrO ２By increasing the content of the monomer and / or oligomer, the tan δ peak intensity can be lowered, and if a higher tan δ peak intensity is desired, the opposite can be adjusted. When the resin composition layer contains a monomer and / or oligomer, the tan δ peak intensity can be lowered by increasing the content of the monomer and / or oligomer having a low viscosity, and if a higher tan δ peak intensity is desired, the opposite can be adjusted. A specific example of a low-viscosity monomer is 1,6-hexanediol diacrylate, and a specific example of a low-viscosity oligomer is an oligomer having a weight-average molecular weight of 1,300 or less.

[0028] Furthermore, the upper limit of the loss tangent (tanδ40) at 40°C obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure is preferably 2.2, more preferably 0.6 to 2.0, even more preferably 0.8 to 1.9, and even more preferably 1.0 to 1.8. By setting the tanδ40 to 0.6 to 2.2, the pressure applied to the resin composition layer during the pressing process is appropriately diffused, improving embeddability and adhesion. In order to control the diffusivity of the pressure applied to the resin composition layer in the preferred temperature range of 20 to 200°C during the pressing process, the loss tangent (tanδ40) at 40°C can be adjusted to 0.6 to 2.2, thereby achieving an even balance between the loss tangent at 20 to 40°C and the loss tangent at 40 to 200°C. The loss tangent (tanδ) is the ratio of loss modulus / storage modulus obtained by dynamic viscoelasticity measurement in a tensile mode at a frequency of 10 Hz and -50 to 150°C. Tan δ 40 can be adjusted by the type and composition of the resin (A) and the type and dispersion state of the metal oxide particles (B). Specifically, the same adjustment method as for the tan δ peak intensity can be used.

[0029] The dynamic viscoelasticity and loss tangent (tanδ) in the present disclosure were measured by the methods described in the Examples below. Note that, when the resin composition layer contains any one of a photopolymerization initiator, a crosslinking agent, and a polymerization initiator, the crosslinking / polymerization reaction is in an incomplete state at the time of measurement. In addition, the above measurement is preferably performed on a sheet having a thickness of 50 μm or more. When measuring a sheet having a thickness less than this, two sets of sealing sheets having no release liner are prepared, and the resin composition layers are bonded together with a laminator to prepare a laminate of protective film / resin composition layer / protective film. Further, the protective film on one side of the laminate is peeled off, and the resin composition layers of the sealing sheets are repeatedly bonded together to form a laminate having a thickness of 50 μm or more, and then the dynamic viscoelasticity may be measured.

[0030] From the viewpoint of embeddability and adhesion, the thickness Ta of the resin composition layer is preferably 1 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm. By setting the thickness Ta of the resin composition layer to 1 to 100 μm, the pressure during the pressing process is appropriately diffused within the resin composition layer and sufficiently smoothed, thereby improving embeddability and adhesion. The resin composition layer may be in the form of a single layer or a laminate of two or more layers. The thickness Ta in the present disclosure was measured using the method described in the Examples below.

[0031] CIEL of resin composition layer ＊ a ＊ b ＊ Saturation in color space C ＊ is preferably 0 to 10, more preferably 0 to 5, and even more preferably 0 to 3.

[0032] Saturation C ＊ is an index that indicates the vividness of a color tone, and chromaticity a ＊ and b ＊ The value is calculated from the following formula 1: ＊ = (a ＊２ +b ＊２ ) ０．５ (Formula 1)

[0033] In Formula 1, C ＊ is the saturation, and a ＊ and b ＊ are the chromaticity a＊ and b ＊ All values ​​were measured in accordance with JIS Z 8781-4. ＊ By setting the chroma C to 0 to 10, the influence of the color tone of the coating film on the color tone of the optical semiconductor is suppressed, and seamlessness and visibility are improved. ＊ was measured by the method described in the Examples below. ＊ can be adjusted by the type of resin (A), the type and content of metal oxide particles (B), and the type and content of monomers and / or oligomers. When the resin (A) contains a (meth)acrylic resin (a), the chroma C can be adjusted by increasing the content of the functional group-containing monomer constituting the (meth)acrylic resin (a). ＊ When the content of the metal oxide particles (B) is increased, the chroma C ＊ can be increased, and the saturation C ＊ When the resin composition layer contains a monomer and / or an oligomer, the chroma C can be reduced by increasing the number of functional groups in the monomer or by increasing the content of the functional group-containing monomer constituting the oligomer. ＊ can be increased, and vice versa if desired to decrease it.

[0034] The haze of the resin composition layer is preferably 12% or less, more preferably 8% or less, and even more preferably 5% or less. The haze in the present disclosure was measured by the method in the Examples described below. The total light transmittance of the resin composition layer is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The total light transmittance of the resin composition layer was measured by the method in the Examples described below. By setting the haze and total light transmittance of the resin composition layer within the above ranges, scattering of light transmitted through the sealing layer is reduced, improving seamlessness and visibility. The haze and total light transmittance of the resin composition layer in the present disclosure can be adjusted by the type of resin (A), the type, dispersion state and content of the metal oxide particles (B), and the type and content of the monomer and / or oligomer. When the resin (A) contains a (meth)acrylic resin (a) or when the metal oxide particles (B) contain ZrO ２ When it contains, the haze and total light transmittance can be reduced.

[0035] [Method for Forming Resin Composition Layer] The method for forming the resin composition layer is not particularly limited, but a suitable example is a method of forming a resin composition layer by coating a resin composition in which a solvent has been added to the components constituting the resin composition layer. The addition of a solvent is intended to adjust the viscosity level to a level suitable for coating. For coating, known coating machines and techniques such as a comma coater, die coater, roll coater, lip coater, reverse coater, gravure coater, bar coater, curtain coater, dip coating, spin coating, silk screen, and casting can be used. The solvent contained in the resin composition can be removed by a drying process after coating. In a preferred embodiment, the resin composition is applied to a support such as a protective film or release liner, and the coated film is then heated and dried using a hot air oven, infrared heater, or the like to form a resin composition layer on one side of the support. Furthermore, to increase the crosslink density of the resin composition layer, it is preferable to perform an aging treatment such as leaving the resin composition at rest under specific temperature conditions, or to irradiate it with UV light, for example. After coating, the resin composition may be transferred to another support such as a protective film, release liner, or substrate using a laminator.

[0036] [Resin Composition] The resin composition can be obtained by mixing a solvent, resin (A), and metal oxide particles (B) while stirring. The optional solvent is used for the purpose of adjusting processing suitability, such as viscosity, when mixing resin (A) and metal oxide particles (B). Therefore, any solvent compatible with resin (A), such as an ester-based, ether ester-based, ether-based, alcohol-based, or aromatic solvent, can be used as appropriate. Specific examples of suitable solvents include acetone, 2-butanone, ethyl acetate, cyclohexanone, toluene, xylene, isopropyl alcohol, and N-methyl-2-pyrrolidone. For stirring, a known stirring device can be used, and a disperser, mixer, shaker, homogenizer, or the like is preferred.

[0037] To obtain the resin composition, a two-stage or more production process may be employed, in which first, a mixture is prepared by mixing the metal oxide particles (B) with the resin (A) and an optional solvent, and second, the resin (A), a crosslinking agent, a polymerization initiator, and other components are added as necessary.

[0038] [Resin (A)] The weight-average molecular weight (Mw) of resin (A) is preferably 10,000 to 1,000,000. From the viewpoint of light resistance and adhesion, 20,000 to 300,000 is more preferable, and 30,000 to 150,000 is even more preferable. By setting the weight-average molecular weight (Mw) to 1,000,000, entanglement of molecular chains during the heat aging process is facilitated, improving adhesion. Furthermore, the ratio (Mw / Mn) of the number-average molecular weight (Mn) to the weight-average molecular weight (Mw), which indicates the degree of dispersion of resin (A), is preferably 1 to 5, more preferably 2 to 4.5, and even more preferably 2.5 to 4. By setting the Mw / Mn to 1 to 5, the flow rate within the resin when heated is made uniform, making it easier to control the resin's fluidity and improving embeddability. Furthermore, the rate at which the resin wets the adherend is also made uniform, improving adhesion. The weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​measured in terms of polystyrene by gel permeation chromatography (GPC). The weight average molecular weight (Mw) and number average molecular weight (Mn) in the present disclosure were measured by the method described in the Examples below.

[0039] The glass transition temperature (Tg) of the resin (A) is -30°C to 60°C. From the viewpoint of embeddability and adhesion, -20°C to 50°C is more preferable, -15°C to 40°C is even more preferable, -10°C to 30°C is even more preferable, and 0°C to 20°C is particularly preferable. By setting the glass transition temperature (Tg) to -30°C or higher, the fluidity and wettability of the resin (A) in the pressing process can be made favorable, thereby improving embeddability and adhesion. By setting the glass transition temperature (Tg) to 60°C or lower, when pressure is applied to the resin composition layer in the pressing process, the molecular motion of the resin (A) contained in the resin composition layer is activated, making it easier for molecular chain entanglements to disentangle. When the molecular chain entanglements are disentangled, the resin can deform to conform to uneven adherends such as substrates and optical semiconductor elements, reducing voids between the optical semiconductor element and the resin composition layer and leading to improved embeddability.

[0040] The glass transition temperature (Tg) of the resin (A) in the present disclosure refers to the glass transition temperature (Tg) before thermal crosslinking and before photocrosslinking when the resin (A) undergoes a crosslinking reaction due to heat or light. The glass transition temperature (Tg) of the resin (A) in the present disclosure is measured by the method described in the examples below.

[0041] The resin (A) can be used alone or in combination of two or more. The content of the resin (A) is preferably 10 to 98% by mass, more preferably 40 to 95% by mass, and even more preferably 60 to 90% by mass, based on the total amount (100% by mass) of the resin composition layer. When two or more types of resin (A) are contained, the content of each resin (A) is preferably 5% by mass or more, and the total content is preferably within the above-mentioned range. By setting the content of the resin (A) to 10 to 98% by mass, compatibility with the metal oxide particles (B) is improved, and visibility is improved.

[0042] Suitable examples of the resin (A) include (meth)acrylic resin (a), urethane resin (b) such as polyurethane resin or polyurethane urea resin, maleic acid resin, styrene-maleic acid copolymer, polystyrene resin, polybutadiene resin, polyester resin, condensation polyester resin, addition polyester resin, melamine resin, epoxy resin, polycarbonate resin, oxetane resin, phenoxy resin, polyimide resin, polyamideimide resin, alkyd resin, amino resin, polyamide resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluororesin, butyral resin, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, vinyl resin, rubber resin, cyclized rubber resin, cellulose, polyethylene (HDPE, LDPE), etc. From the viewpoint of embeddability, it is preferable to contain at least one of the (meth)acrylic resin (a) and the urethane resin (b). Furthermore, from the viewpoint of adhesion, it is more preferable to contain the (meth)acrylic resin (a).

[0043] The resin (A) preferably has multiple functional groups that can be used in crosslinking reactions induced by heat or light. The functional groups may be appropriately selected depending on the combination with the crosslinking agent, thermal polymerization initiator, or photopolymerization initiator described below, and may also be self-crosslinkable functional groups. Examples of functional groups include hydroxyl groups, carboxyl groups, amino groups, epoxy groups, oxetanyl groups, oxazoline groups, oxazine groups, aziridine groups, thiol groups, isocyanate groups, blocked isocyanate groups, silanol groups, vinyl groups, and acryloyl groups. From the viewpoint of dispersibility of the metal oxide particles (B), carboxyl groups, hydroxyl groups, and epoxy groups are preferred. When the resin (A) has a carboxyl group, the acid value of the resin (A) is preferably 1 to 45 mgKOH / g, more preferably 3 to 30 mgKOH / g, and even more preferably 5 to 20 mgKOH / g. By setting the acid value of the resin (A) to 1 to 45 mgKOH / g, the crosslinking density with the crosslinking agent is optimized, improving adhesion. The acid value in the present disclosure was measured by the method described in the Examples below.

[0044] When a crosslinking reaction is induced by light, the resin (A) preferably has one or more unsaturated bonds per molecule. It is also preferable that a photopolymerization initiator be contained. Examples of photopolymerization initiators include triazine-based photopolymerization initiators, borate-based photopolymerization initiators, carbazole-based photopolymerization initiators, acetophenone-based photopolymerization initiators, and oxime ester-based photopolymerization initiators. Acetophenone-based photopolymerization initiators and oxime ester-based photopolymerization initiators are preferred because they cause less yellowing during the heat aging process. From the viewpoint of preventing yellowing, the content of the photopolymerization initiator is preferably 0.5 to 10% by mass, and more preferably 0.5 to 5% by mass, based on the total amount (100% by mass) of the resin composition layer.

[0045] When the crosslinking reaction is caused by heat, preferred embodiments include a first embodiment in which a crosslinking agent is combined with the compound, and a second embodiment in which a thermal polymerization initiator is combined with the compound.

[0046] [(Meth)acrylic Resin (a)] In the present disclosure, the (meth)acrylic resin (a) is an acrylic copolymer (polymer) obtained by copolymerizing a monomer containing a (meth)acrylic acid ester monomer, and is a polymer having structural units based on 25 to 20,000 monomers, and the weight-average molecular weight of the (meth)acrylic resin (a) is 10,000 to 1,000,000. A suitable example of the (meth)acrylic acid ester monomer is a (meth)acrylic acid alkyl ester monomer. When a crosslinked structure is formed, a (meth)acrylic copolymer obtained by copolymerizing a functional group-containing monomer and a (meth)acrylic acid ester monomer is preferred.

[0047] The (meth)acrylic acid alkyl ester monomer is a compound obtained by esterifying (meth)acrylic acid to introduce an alkyl group or a cycloalkyl group, and the alkyl group or cycloalkyl group may be any of a linear, branched, or cyclic saturated aliphatic hydrocarbon group. The saturated aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and more preferably a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, and (meth)acrylic acid. decyl, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. Among these, from the viewpoint of dispersibility of the metal oxide particles (B), it is particularly preferable to use methyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate, and it is particularly preferable to use methyl (meth)acrylate and n-butyl (meth)acrylate.

[0048] From the viewpoint of adhesion, the structural unit derived from a (meth)acrylic acid alkyl ester monomer is preferably 1 to 100% by mass, more preferably 20 to 99.9% by mass, and even more preferably 80 to 99.7% by mass, relative to 100% by mass of the (meth)acrylic resin (a).

[0049] The (meth)acrylic resin (a) preferably has a structural unit derived from a functional group-containing monomer and / or an unsaturated bond. Examples of functional group-containing monomers include carboxy group-containing monomers, hydroxy group-containing monomers, epoxy group-containing monomers, and amino group-containing monomers. By containing a functional group-containing monomer, the cohesive strength of the resin (A) is improved, and a tough resin composition layer is obtained. In particular, it is preferable to contain a carboxy group-containing monomer, a hydroxy group-containing monomer, or an epoxy group-containing monomer.

[0050] Examples of the carboxy group-containing monomer include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, and isocrotonic acid. Among these, (meth)acrylic acid is preferred from the viewpoint of adhesion.

[0051] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-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. Among these, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are more preferred from the viewpoint of adhesion.

[0052] Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate. Among these, it is preferable to include glycidyl (meth)acrylate from the viewpoint of adhesion.

[0053] Examples of amino group-containing monomers include (meth)acrylic acid monoalkylamino esters such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate.

[0054] The total amount of structural units derived from functional group-containing monomers is preferably 0.1 to 20% by mass relative to 100% by mass of the (meth)acrylic resin (a). By adjusting the amount within this range, the cohesive strength can be adjusted by reaction with the crosslinking agent. The amount of structural units derived from carboxy group-containing monomers is preferably 0.1 to 10% by mass relative to 100% by mass of the (meth)acrylic resin (a). Being within this range can enhance adhesion. The amount of structural units derived from hydroxyl group-containing monomers is preferably 0.1 to 10% by mass relative to 100% by mass of the (meth)acrylic resin (a). Being within this range can enhance adhesion. The amount of structural units derived from epoxy group-containing monomers is preferably 0.1 to 15% by mass relative to 100% by mass of the (meth)acrylic resin (a). Being within this range can enhance adhesion.

[0055] A more preferred example of the functional group-containing monomer constituting the (meth)acrylic resin (a) is one in which a carboxyl group-containing monomer and a hydroxyl group-containing monomer are not simultaneously contained, which allows the cohesive strength of the (meth)acrylic resin (a) to be adjusted and the adhesion to be improved.

[0056] The (meth)acrylic resin (a) may contain structural units derived from other monomers copolymerizable with (meth)acrylic acid alkyl esters and functional group-containing monomers. Examples include monomers having an alkyleneoxy group and other vinyl monomers. Examples include methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, and acrylamide. The structural units derived from the other monomers preferably account for 0.1 to 20% by mass of 100% by mass of the (meth)acrylic copolymer.

[0057] The (meth)acrylic resin (a) is obtained by polymerizing an acrylic monomer mixture. A polymerization initiator can be used during polymerization, if necessary. The content of the polymerization initiator is, for example, 0.01 to 10% by mass relative to 100% by mass of the monomer mixture. The polymerization method is not limited. For example, polymerization can be carried out by solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization, with solution polymerization being particularly preferred due to ease of polymerization control. Examples of solvents used in solution polymerization include acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, and cyclohexanone. The polymerization temperature can be, for example, 60 to 120°C, and the polymerization time can be approximately 2 to 12 hours.

[0058] The polymerization initiator is preferably a radical polymerization initiator. Suitable radical polymerization initiators include peroxides and azo compounds. Any of the thermal radical polymerization initiators described below can also be used, and specifically, 2,2'-azobisisobutyronitrile (abbreviation: AIBN) is preferred.

[0059] [Urethane Resin (b)] In the present disclosure, urethane resin (b) is a general term for a compound containing two or more urethane bonds per molecule. Urethane resins can be obtained by reacting a polyisocyanate with a polyol. The polyisocyanate may be any polyisocyanate having two or more isocyanate groups per molecule. From the viewpoint of dispersibility of the metal oxide particles (B), diisocyanates or triisocyanates are preferred, with diisocyanates being more preferred. The diisocyanate may be appropriately selected from known aliphatic diisocyanates such as hexamethylene diisocyanate and known aromatic diisocyanates such as benzene-1,3-diisocyanate. Furthermore, an isocyanate-terminated prepolymer obtained by reacting a polyol with an excess amount of polyisocyanate may be used as an intermediate for the urethane resin. The polyol may be any polyol having two or more hydroxyl groups per molecule. From the viewpoint of dispersibility of the metal oxide particles (B), diols or triols are preferred, with diols being more preferred. The diol may be appropriately selected from known aliphatic diols such as ethylene glycol and known aromatic diols such as benzenediol. Prepolymers such as polyether polyols, polyester polyols, and polycarbonate polyols may also be used.

[0060] The urethane resin (b) may be a polyurethane urea resin further having a urea bond. The polyurethane urea resin can be synthesized, for example, by reacting a urethane resin having an isocyanate group at its terminal with a polyamine. The polyamine may be any polyamine having two or more amino groups per molecule, and from the viewpoint of dispersibility of the metal oxide particles (B), a diamine or triamine is preferred, and a diamine is more preferred. The diamine can be appropriately selected from known aliphatic diamines such as ethylenediamine and known aromatic diamines such as phenylenediamine.

[0061] [Metal Oxide Particles (B)] In this embodiment, the metal oxide particles (B) have the function of improving the fluidity of the resin (A) and improving the embeddability between optical semiconductor elements. In addition, they have the function of adjusting the refractive index. Examples of metals constituting the metal oxide particles (B) include Ti, Al, Zr, In, Zn, Sn, La, Y, Ce, Mg, Hf, Ta, Ba, Ca, and Si. From the viewpoint of improving embeddability and seamlessness, Ti, Al, and Zr are preferred, and Zr is more preferred. The metal oxide particles (B) may be used singly or in combination of two or more types.

[0062] As the Ti-containing metal oxide particles (B), titanium monoxide (TiO), titanium dioxide (TiO ２ ), titanium trioxide (TiO ３ ), barium titanate (BaTiO ３ ), perovskite (CaTiO ３ Examples of the metal oxide particles (B) containing Al include aluminum oxide (Al ２ O ３ ), spinel (MgAl ２ O ４ As the metal oxide particles (B) containing Zr, zirconium oxide (ZrO ２ Among these, aluminum oxide (Al ) is preferred from the viewpoint of embedding properties. ２ O ３ ), titanium dioxide (TiO ２ ), zirconium oxide (ZrO ２ ) is preferred, and zirconium oxide (ZrO ２ ) is particularly preferred.

[0063] As the metal oxide particles (B) other than those mentioned above, indium oxide (In ２ O ３ ), zinc oxide (ZnO), tin oxide (SnO ２ ), lanthanum oxide (La ２ O ３ ), yttrium oxide (Y ２ O ３ ), cerium oxide (CeO ２ ), magnesium oxide (MgO), hafnium oxide (HfO ２), tantalum pentoxide (Ta ２ O ５ ), niobium pentoxide (Nb ２ O ５ ), silicon dioxide (SiO ２ ), indium tin oxide (ITO), antimony tin oxide (ATO), and the like.

[0064] The metal oxide particles (B) are preferably surface-modified with a surface modifier, such as an organic acid, a silane coupling agent, a surfactant, a titanium coupling agent, or a metal impurity, and preferably contain an organic acid.

[0065] From the viewpoint of dispersibility, the metal oxide particles (B) have a specific surface area measured by the BET method of 10 to 400 m ２ / g, and 10 to 150m ２ / g, and more preferably 20 to 84 m ２ The specific surface area measured by the BET method can be measured in accordance with JIS Z 8830.

[0066] The number-average primary particle diameter of the metal oxide particles (B) is 5 to 50 nm, preferably 5 to 30 nm, more preferably 7 to 25 nm, and particularly preferably 10 to 20 nm. By setting the diameter to 5 to 50 nm, the fluidity of the resin composition layer is improved, resulting in improved embeddability. Furthermore, the viscosity of the resin composition is easily maintained at a level suitable for coating. Furthermore, the dispersibility in the resin is improved, making it easier to exhibit the refractive index adjusting function. The number-average primary particle diameter of the metal oxide particles (B) can be determined by randomly selecting 20 particles that can be observed from an image of the metal oxide particles (B) magnified approximately 50,000 to 1,000,000 times using a transmission electron microscope (TEM), field emission transmission electron microscope (FE-TEM), field emission scanning electron microscope (FE-SEM), or the like, measuring the length of the particles in the major axis direction, and calculating the arithmetic average.

[0067] The content of the metal oxide particles (B) is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and even more preferably 5 to 30% by mass, based on the total amount (100% by mass) of the resin composition layer. This is because a content of 1 to 40% by mass improves the flow of the resin composition and provides excellent embeddability. Furthermore, the dispersibility in the resin is improved, resulting in improved visibility.

[0068] It is preferable to disperse the metal oxide particles (B) in the resin (A) and use the resulting metal oxide particle dispersion in order to adjust the loss tangent (tan δ) and embeddability of the resin composition layer. The dispersing machine used for mechanical crushing in the dispersion process may be any commonly used dispersing machine, including, for example, a ball mill, a roll mill, a sand mill, a bead mill, and a Nanomizer. Among these, a bead mill is preferably used. Examples of such machines include a Super Mill, a sand grinder, an agitator mill, a Grain Mill, a Dyno Mill, a Pearl Mill, and a Cobol Mill (all trade names).

[0069] In the present disclosure, from the viewpoint of storage stability of the resin composition layer, it is preferable to use a dispersant in the dispersion treatment of the metal oxide particles (B). In the present disclosure, the dispersant has the function of imparting repulsive forces between particles so that the particles divided through the above-mentioned dispersion treatment do not re-aggregate. As the dispersant, a conventionally known compound can be used, for example, a cationic, anionic, or nonionic surfactant, a cationic, anionic, or nonionic polymer dispersant, or a pigment derivative dispersant.

[0070] Examples of polymeric dispersants include polyurethane resins, polyester resins, polyamide resins, (meth)acrylic resins, polycarboxylic acids (salts), styrene copolymers, polyalkylene oxide derivatives, and phosphate ester resins. The acid value of the polymeric dispersant is preferably 5 to 450 mgKOH / g, more preferably 46 to 300 mgKOH / g, and even more preferably 50 to 200 mgKOH / g. A moderate acid value provides excellent electrostatic repulsion and a dispersion with excellent storage stability. The acid value in this disclosure is measured by the method described in the Examples below. The weight-average molecular weight (Mw) of the polymeric dispersant is preferably 1,000 to 50,000, more preferably 3,000 to 30,000. A moderate weight-average molecular weight (Mw) improves the adsorption rate to the colorant and results in a dispersion with excellent stability. The weight-average molecular weight (Mw) in this disclosure is measured by the method described in the Examples below.

[0071] Pigment derivative dispersants are compounds having an acidic group, a basic group, a neutral group, or the like in the organic dye residue. Examples include compounds having an acidic substituent such as a sulfo group, a carboxyl group, or a phosphate group, as well as amine salts of these, compounds having a basic substituent such as a sulfonamide group, an amide group, or a terminal tertiary amino group, and compounds having a neutral substituent such as a phenyl group or a phthalimidoalkyl group. Examples of organic dyes include phthalocyanine pigments, diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiazine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, threne pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo. These dispersants may be used individually or in combination of two or more. By using these dispersants, it becomes possible to prevent the metal oxide particles (B) contained in the resin composition layer from aggregating over time, and to prevent unevenness in the encapsulating sheet.

[0072] The content of the dispersant (total content when two or more types are included) is preferably 0.01 to 10 mass %, and more preferably 0.1 to 5 mass %, based on the total amount (100 mass %) of the resin composition layer. When the dispersant is contained in an amount of 0.01 mass % or more, the cohesion property of the resin composition layer over time becomes good, and when the dispersant is contained in an amount of 10 mass % or less, the viscosity of the metal oxide particle (B) dispersion falls within a suitable range, resulting in good coating suitability.

[0073] [First embodiment] In a first embodiment according to the present disclosure, the resin composition layer includes a resin (A) and a crosslinking agent. The first embodiment is characterized in that, by heating the resin composition layer, a crosslinked structure is formed by a reaction between the functional groups of the resin (A) and the crosslinking agent. From the viewpoint of coating film strength, the resin (A) is preferably the resin (A) having a weight average molecular weight (Mw) of 10,000 or more, and is more preferably the (meth)acrylic resin (a).

[0074] [Crosslinking Agent] In the first embodiment, the resin composition layer of the present disclosure preferably contains a crosslinking agent to promote the formation of a crosslinked structure. The crosslinking agents may be used alone or in combination of two or more. The crosslinking agent crosslinks with the reactive functional groups of the resin (A) during the heat pressing or heat aging step in the pressing process, thereby increasing the cohesive strength of the resin composition layer and improving adhesion. The crosslinking agent has multiple functional groups capable of reacting with the functional groups of the resin (A). Examples of crosslinking agents include known compounds such as silane coupling agents, epoxy-based crosslinking agents, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, and amine compounds. From the viewpoint of adjusting the loss tangent (tan δ) of the resin composition layer, silane coupling agents, epoxy-based crosslinking agents, aziridine compounds, imidazole compounds, and isocyanate compounds are preferred, and from the viewpoint of adhesion, epoxy-based crosslinking agents are more preferred.

[0075] Silane coupling agents are compounds in which a hydrolyzable group such as a methoxy group or an ethoxy group and a functional group such as an epoxy group are bonded to a silicon atom via an alkylene group. Examples of the silane coupling agent include alkoxysilane compounds having a (meth)acryloxy group, such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxypropyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; alkoxysilane compounds having a vinyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; Alkoxysilane compounds having an amino group such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane; alkoxysilane compounds having an epoxy group, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane;Examples of suitable alkoxysilane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane; 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, hexamethyldisilazane, and silicone resins having an alkoxysilyl group in the molecule. From the viewpoint of adhesion, alkoxysilane compounds are preferred, and 3-glycidoxypropyltrimethoxysilane is more preferred.

[0076] The epoxy-based crosslinking agent is a compound having two or more epoxy groups per molecule, other than the (meth)acrylic resin (a) having the epoxy group-containing monomer described above. Regarding the properties of the epoxy-based crosslinking agent, using a liquid crosslinking agent can lower the tan δ peak temperature of the resin composition layer, thereby enabling good adhesion between the optical semiconductor element and the resin composition layer. On the other hand, using a solid crosslinking agent can increase the tan δ peak temperature of the resin composition layer, controlling the stickiness of the resin composition layer and adjusting seamlessness. Examples of epoxy-based crosslinking agents include glycidyl ether-type epoxy crosslinking agents, glycidylamine-type epoxy crosslinking agents, glycidyl ester-type epoxy crosslinking agents, cycloaliphatic (alicyclic) epoxy crosslinking agents, bisphenol-type epoxy crosslinking agents, and hydrogenated bisphenol-type epoxy crosslinking agents. From the viewpoint of adhesion, bisphenol-type epoxy crosslinking agents and hydrogenated bisphenol-type epoxy crosslinking agents are preferred.

[0077] Examples of glycidyl ether-type epoxy crosslinking agents include cresol novolac-type epoxy crosslinking agents, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane. Examples of glycidyl amine-type epoxy crosslinking agents include tetraglycidyldiaminodiphenylmethane and tetraglycidylmeta-xylylenediamine. Examples of glycidyl ester-type epoxy crosslinking agents include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate. Examples of cyclic aliphatic (alicyclic) epoxy crosslinking agents include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis(epoxycyclohexyl)adipate. Examples of bisphenol-type epoxy crosslinking agents include bisphenol A-type epoxy crosslinking agents, bisphenol F-type epoxy crosslinking agents, bisphenol S-type epoxy crosslinking agents, and bisphenol AD-type epoxy crosslinking agents. Bisphenol A-type epoxy crosslinking agents are particularly preferred from the standpoint of adhesion. Examples of hydrogenated bisphenol epoxy crosslinking agents include hydrogenated bisphenol A epoxy crosslinking agents, hydrogenated bisphenol F epoxy crosslinking agents, etc. In particular, hydrogenated bisphenol A epoxy crosslinking agents are preferred from the viewpoint of adhesion.

[0078] Examples of the aziridine compound include trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane.

[0079] Imidazole compounds include 2-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, imidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]- Examples of imidazole compounds include ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Further examples include compounds with improved storage stability, such as a type insoluble in a solvent obtained by reacting an imidazole compound with an epoxy resin, or a type in which an imidazole compound is encapsulated in microcapsules.

[0080] The isocyanate compound is an isocyanate having two or more isocyanate groups. Examples of the isocyanate compound include isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates, as well as biuret, nurate, and adduct forms thereof.

[0081] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate. 2,4-tolylene diisocyanate is preferred from the viewpoint of adhesion. Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate. Examples of aromatic aliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate. Examples of alicyclic polyisocyanates include 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatemethyl)cyclohexane.

[0082] The biuret form is a self-condensation product having a biuret bond formed by the self-condensation of an isocyanate monomer. An example of the biuret form is the biuret form of hexamethylene diisocyanate. The nurate form is a trimer of an isocyanate monomer. Examples include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, and a trimer of tolylene diisocyanate. The adduct form is a bifunctional or higher isocyanate compound formed by the reaction of an isocyanate monomer with a bifunctional or higher low-molecular-weight active hydrogen-containing compound. Examples of the adduct include a compound obtained by reacting trimethylolpropane with hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane with tolylene diisocyanate, a compound obtained by reacting trimethylolpropane with xylylene diisocyanate, a compound obtained by reacting trimethylolpropane with isophorone diisocyanate, and a compound obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate.

[0083] The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct or nurate, which is a reaction product of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. The isocyanate compound is preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a nurate of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, a nurate of tolylene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, or a nurate of isophorone diisocyanate, and more preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, or a trimethylolpropane adduct of isophorone diisocyanate.

[0084] In the first embodiment, from the viewpoint of coating film strength, it is preferable to contain two or more types of crosslinking agents. From the viewpoint of adjusting the loss tangent (tan δ) of the resin composition layer, specific preferred examples include those containing two or more types selected from a silane coupling agent, an epoxy-based crosslinking agent, an aziridine compound, and an isocyanate compound.

[0085] The content of the crosslinking agent (total content when two or more types are used in combination) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, embeddability and adhesion can be suitably adjusted.

[0086] [Crosslinking Adjusting Component] The resin composition layer of the first embodiment preferably contains a crosslinking adjusting component such as a crosslinking accelerator or a crosslinking retarder in order to adjust the crosslinking rate and the physical properties of the resin composition layer. The crosslinking accelerator is not particularly limited and can be selected appropriately. Specific examples of the crosslinking accelerator include phosphorus-based crosslinking accelerators, amine-based crosslinking accelerators, and guanidine-based crosslinking accelerators. These may be used alone or in combination of two or more. From the viewpoint of coating suitability, the content of the crosslinking accelerator is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass, based on the total amount (100% by mass) of the resin composition layer.

[0087] [Second Embodiment] In a second embodiment according to the present disclosure, the resin composition layer contains a resin (A) and a thermal polymerization initiator. Furthermore, the resin composition layer preferably contains a monomer and / or an oligomer. The second embodiment is characterized in that, by heating the resin composition layer, radicals or ions (cations or anions) are generated from the thermal polymerization initiator, and a polymerization reaction occurs at an unsaturated bond site in either the resin (A), the monomer, or the oligomer, thereby increasing the molecular weight of the resin composition layer. When the resin composition layer contains a monomer or an oligomer, the resin (A), the monomer, and the oligomer may bond to each other. From the viewpoint of coating film strength, the resin (A) preferably has a weight-average molecular weight (Mw) of 10,000 or more, and is more preferably the (meth)acrylic resin (a).

[0088] [Thermal Polymerization Initiator] In this embodiment, a thermal cationic polymerization initiator or a thermal radical polymerization initiator can be used as the thermal polymerization initiator. From the viewpoint of the storage stability of the resin composition layer, a thermal radical polymerization initiator is preferred. These initiators may be used alone or in combination of two or more. The thermal cationic polymerization initiator has the function of generating ions by heat. Examples of the thermal cationic polymerization initiator include sulfonium cations, quaternary ammonium cations, and iodonium cations as cationic components. Examples of the anionic components include antimony hexafluoride anions, phosphorus hexafluoride anions, tetrakis(pentafluorophenyl)borate anions, and trifluoromethanesulfonic acid. The thermal radical polymerization initiator has the function of generating radicals by heat. Examples of the thermal radical polymerization initiator include azo thermal polymerization initiators and organic peroxide polymerization initiators.

[0089] Examples of organic peroxide polymerization initiators include diacetyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)hexane, and dialkyl peroxides such as (2-ethylhexanoyl)(t-butyl)peroxide; dipropionyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, bis(3,5,5-trimethylhexanoyl)peroxide, 1,1,3,3-tetramethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, Peroxy esters such as t-butylperoxyisobutyrate, di-t-butylperoxyhexahydroterephthalate, 1,1,3,3-tetramethylbutylperoxy-3,5,5-trimethylhexanate, t-amylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, dibutylperoxytrimethyladipate, 2,5-dimethyl-2,5-di-2-ethylhexanoylperoxyhexane, t-hexylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, and t-butylperoxy-2-ethylhexyl monocarbonate;Ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, t-butyl benzoate, and pivaloyl t-butyl peroxide; Peroxyketals such as 2,2-bis(t-butylperoxy)butane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, and 4,4-bis(t-butylperoxy)butyl pentanoate; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and p-menthane hydroperoxide; diacyl peroxides such as dibenzoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, diisobutyryl peroxide, bis-3,5,5-trimethylhexanol peroxide, m-toluylbenzoyl peroxide, succinic acid peroxide, and 2,4-dichlorobenzoyl peroxide;Examples of peroxydicarbonates include, but are not limited to, bis(t-butylcyclohexyl)peroxydicarbonate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, di-2-ethylhexyl peroxycarbonate, di-sec-butyl peroxycarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-amylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, and 6-bis(t-butylperoxycarboxyloxy)hexane. From the viewpoint of storage stability, dialkyl peroxides are preferred, and di-t-butyl peroxide is more preferred.

[0090] Examples of the azo thermal polymerization initiator include 2,2'-azobisbutyronitrile such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobisvaleronitrile such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile); 1,1'-azobis-1-alkanenitriles such as 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobispropionitriles such as 2,2'-azobis(2-hydroxymethylpropionitrile); 2,2'-azobispropionamides such as 2,2'-azobis(N-butyl-2-methylpropionamide) and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); Other examples include dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 1-[(1-cyano-1-methylethyl)azo]formamide, and the like. Examples of azo compounds having a carboxyl group or a hydroxyl group include, but are not limited to, 4,4'-azibis(4-cyanopentanoic acid), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), and 2,2'-azobis(N-(carboxyethyl)-2-methylpropionamidine) tetrahydrate. From the viewpoint of storage stability, 2,2'-azobispropionamides are preferred, and 2,2'-azobis(N-butyl-2-methylpropionamide) is more preferred.

[0091] The 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 60 to 200° C., more preferably 80 to 180° C., even more preferably 100 to 150° C., and particularly preferably 105 to 130° C. By setting the temperature to 60° C. or higher, the storage stability of the resin composition layer can be improved, and by setting the temperature to 200° C. or lower, the heat aging step of the sealing layer can be shortened.

[0092] The 10-hour half-life temperature is the temperature at which the thermal polymerization initiator is thermally decomposed and reduced to half of its initial value after 10 hours. Specifically, a thermal polymerization initiator solution is prepared using a solvent inert to the radicals of the thermal polymerization initiator and sealed in a nitrogen-purged glass tube. This is immersed in a thermostatic chamber set at a predetermined temperature for 10 hours to cause thermal decomposition, and the amount of remaining thermal polymerization initiator is measured. This series of steps is carried out at several temperatures, and the half-life can be calculated from the resulting straight line.

[0093] The content of the thermal radical polymerization initiator (total content when two or more types are used in combination) is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and even more preferably 0.1 to 5% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, adhesion can be suitably adjusted.

[0094] [Monomer] In the present embodiment, a monomer refers to a compound having a radically polymerizable group, which is the minimum structural unit for constituting an oligomer or polymer to be added to a resin composition. Examples of radically polymerizable groups include a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, and an unsaturated carboxylic acid group. The monomer may be a monofunctional monomer or a polyfunctional monomer. In this specification, "monofunctional" refers to a compound having only one polymerizable group per molecule, and "bifunctional" and "trifunctional" refer to compounds having two and three polymerizable groups per molecule, respectively. In this specification, bifunctional or higher functional compounds are collectively referred to as "polyfunctional."

[0095] Specific examples of the monomer include 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, dipropylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylhexyl EO-modified (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxypropyl methyl ... hydroxybutyl (meth)acrylate, β-carboxyethyl (meth)acrylate, monohydroxyethyl phthalate (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tetrahydrofurfuryl acrylate, alkoxylated tetrahydrofurfuryl acrylate, caprolactone (meth)acrylate, isononyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isoamyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, 3,3,5-trimethylcyclohexanol (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (oxyethyl) (meth)acrylate, 1,4-cyclohexanedimethanol (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, benzyl (meth)acrylate, phenol EO-modified (meth)acrylate, EO-modified (2) nonylphenol acrylate, PO-modified nonylphenol acrylate, phenoxyethyl (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, hydroxyethyl acrylamide,Monofunctional (meth)acrylate monomers having one (meth)acryloyl group in the molecule, such as dimethylaminopropyl acrylamide, N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, 3-((meth)acryloyloxy)propyltrimethoxysilane, 3-((meth)acryloyloxy)propyltriethoxysilane, and 2-(meth)acryloyloxyethyl isocyanate; monofunctional vinyl monomers having one N-vinyl group in the molecule, such as N-vinylcarbazole, 1-vinylimidazole, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinyloxazolidinone, and N-vinylmethyloxazolidinone; 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, polyethylene glycol (300) di(meth)acrylate, polyethylene glycol (400) di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, Dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, EO-modified (2) 1,6-hexanediol di(meth)acrylate, PO-modified 1,6-hexanediol di(meth)acrylate, EO-modified neopentyl glycol di(meth)acrylate, PO-modified (2) neopentyl glycol di(meth)acrylate, (neopentyl glycol-modified) trimethylolpropane di(meth)acrylate, EO-modified trimethylol acid diacrylate, tricyclodecane di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, bisphenol A di(meth)acrylate, EO-modified (4) bisphenol A di(meth)acrylate, PO-modified (4) bisphenol A di(meth)acrylate,Bifunctional (meth)acrylate monomers having two (meth)acryloyl groups in the molecule, such as EO / PO-modified bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, EO-modified bisphenol F di(meth)acrylate, PO-modified bisphenol F di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, ethoxylated cyclohexanemethanol di(meth)acrylate, and dicyclopentanyl di(meth)acrylate; Bifunctional (meth)acrylate monomers having one (meth)acryloyl group and one allyl group in the molecule, such as 2-(allyloxymethyl)methyl acrylate and 2-(allyloxymethyl)ethyl acrylate; Trimethylolpropane tri(meth)acrylate, EO-modified (3) Trimethylolpropane tri(meth)acrylate, EO-modified (6) Trimethylolpropane tri(meth)acrylate, PO-modified (3) Trimethylolpropane tri(meth)acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate, ethoxylated isocyanuric acid tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylol Trifunctional (meth)acrylate monomers having three (meth)acryloyl groups in the molecule, such as propane tri((meth)acryloyloxypropyl)ether, alkylene oxide-modified isocyanurate tri(meth)acrylate, dipentaerythritol propionate tri(meth)acrylate, tri((meth)acryloyloxyethyl)isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri(meth)acrylate, sorbitol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, EO-modified glycerin tri(meth)acrylate, and PO-modified glyceryl tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, EO-modified (4) pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and sorbitol tetra(meth)acrylate,Examples of the monomer include, but are not limited to, tetrafunctional (meth)acrylate monomers having four acryloyl groups in the molecule, such as dipentaerythritol propionate tetra(meth)acrylate and tetramethylolmethane tetra(meth)acrylate, pentafunctional (meth)acrylate monomers having five (meth)acryloyl groups in the molecule, such as dipentaerythritol penta(meth)acrylate and sorbitol penta(meth)acrylate, and hexafunctional (meth)acrylate monomers having six (meth)acryloyl groups in the molecule, such as dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate of phosphazene, and ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate. Note that, above, "EO" refers to "ethylene oxide," and "PO" refers to "propylene oxide." The monomers may be used alone or in combination of two or more.

[0096] Among these, from the viewpoint of embeddability, the (meth)acrylate compound preferably contains a di- to hexa-functional (meth)acrylate monomer, and more preferably a di- or tri-functional (meth)acrylate monomer. Specifically, 1,6-hexanediol di(meth)acrylate, EO-modified (4) bisphenol A di(meth)acrylate, and EO-modified (3) trimethylolpropane tri(meth)acrylate are preferred.

[0097] The content of the monomer (total content when two or more types are used in combination) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 15% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, embeddability can be suitably adjusted.

[0098] [Oligomer] In the present embodiment, an oligomer refers to a polymer having structural units based on 2 to 100 monomers containing a radically polymerizable group, and has a weight-average molecular weight of 400 to 9,999. The weight-average molecular weight of the oligomer is more preferably 400 to 5,000, and even more preferably 500 to 3,000. Examples of polymerizable groups contained in the oligomer include a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, and an unsaturated carboxylic acid group, with a (meth)acryloyl group being preferred. The radically polymerizable oligomer may be monofunctional or polyfunctional. The number of polymerizable groups per molecule is preferably 1 to 6, and more preferably 2 to 4.

[0099] Specific examples of the oligomer include urethane acrylate oligomers such as aliphatic urethane acrylate oligomers and aromatic urethane acrylate oligomers, acrylic ester oligomers, polyester acrylate oligomers, epoxy acrylate oligomers, etc. The oligomers may be used alone or in combination of two or more.

[0100] From the viewpoint of embeddability, the (meth)acrylate compound of the present disclosure preferably contains an alkylene oxide-modified (meth)acrylate compound having two or more (meth)acryloyl groups in the molecule.

[0101] The content of the oligomer (total content when two or more types are used in combination) is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 15% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the content within the above range, embeddability can be suitably adjusted.

[0102] [Other Components] The resin composition layer of the present disclosure may contain other components as long as the object of the present disclosure is not impaired. For example, a colorant, a dispersant, a surface conditioning additive, a softener, an antistatic agent, a lubricant, an antiblocking agent, an adhesion improver, etc. may be added. From the viewpoint of controlling the film properties such as the viscoelasticity of the resin composition layer, it is preferable that the resin composition layer contains a colorant, a surface conditioning additive, and an adhesion improver.

[0103] Examples of colorants include black pigments, black dyes, and pigments such as red, green, blue, yellow, purple, cyan, and magenta. Colors can also be toned by mixing multiple colorants. Carbon black is preferred as the black pigment from the viewpoint of controlling film properties. When the colorant is a pigment, the number-average primary particle diameter is preferably 10 to 100 nm. By setting the colorant within this range, the viscosity of the resin composition can be easily maintained at a level suitable for coating. The number-average primary particle diameter of the pigment can be determined using the same method as for the metal oxide particles (B). From the viewpoint of embeddability, the content of the colorant (the total content when two or more types are included) is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, based on the total amount (100% by mass) of the resin composition layer.

[0104] Examples of surface conditioning additives include surfactants with a weight-average molecular weight (Mw) of 1,000 to 9,999, such as silicone-based, silicone acrylic, fluorine-based, and acetylene glycol-based surfactants, which do not contain radically polymerizable groups. Among these, silicone-based and silicone acrylic surfactants are particularly preferred from the viewpoint of adhesion. Preferred examples of silicone-based surface conditioning additives include modified polysiloxane compounds in which organic groups have been introduced into some of the methyl groups of polydimethylsiloxane. Examples of modifications include, but are not limited to, polyether-modification, methylstyrene-modification, alcohol-modification, alkyl-modification, aralkyl-modification, fatty acid ester-modification, epoxy-modification, amine-modification, amino-modification, and mercapto-modification. These modification methods can be used in combination. Among these, polyether-modified polysiloxane compounds and aralkyl-modified polysiloxane compounds are preferred in terms of compatibility, etc. From the viewpoint of coating suitability, the content of the surface conditioning additive is preferably 0.01 to 10 mass %, more preferably 0.1 to 5 mass %, based on the total amount (100 mass %) of the resin composition layer.

[0105] Examples of adhesion improvers include oligomers having a weight average molecular weight (Mw) of 1,000 to 9,999 that do not contain radical polymerizable groups. Examples include rosin-based resins, terpene-based resins, alicyclic petroleum resins, and aromatic petroleum resins. The weight average molecular weight (Mw) of the adhesion improver is more preferably 2,000 to 8,000, and even more preferably 3,000 to 5,000. From the viewpoint of adhesion, the content of the adhesion improver is preferably 0.1 to 20% by mass, and more preferably 1 to 15% by mass, based on the total amount (100% by mass) of the resin composition layer.

[0106] Hereinafter, the present disclosure will be specifically described with reference to examples and comparative examples, but the present disclosure is not particularly limited to the examples. In the following description, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0107] The values ​​determined in this example were obtained by the following method. [Glass Transition Temperature (Tg) of Resin (A)] A coating solution of Resin (A) was applied to the release layer of a 75 μm thick protective film (SP-PET-O3, manufactured by Mitsui Chemicals Tohcello, Inc.) so that the thickness after drying would be 20 μm. This was then dried for 3 minutes in a hot air oven at 100°C, and the release layer side of a 50 μm thick release liner (SP-PET-O1, manufactured by Mitsui Chemicals Tohcello, Inc.) was then attached to the resin (A) side. The protective film and release liner were then peeled off, and the Tg of the resulting Resin (A) was measured using a differential scanning calorimeter (Discovery DSC 2500, manufactured by TA Instruments). Approximately 2 mg of the sample was placed in an aluminum pan, weighed, and set in a differential scanning calorimeter. Using an aluminum pan of the same type but without the sample as a reference, the pan was held at 100°C for 5 minutes and then rapidly cooled to -50°C using liquid nitrogen. Thereafter, the temperature was increased at a rate of 5°C / min, and the glass transition temperature (Tg) of the resin (A) was determined from the obtained DSC chart.

[0108] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using a GPC "LC-GPC system" manufactured by Shimadzu Corporation, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by conversion using polystyrene of known molecular weight as a standard substance. Apparatus name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation Column: Four GMHXL columns manufactured by Tosoh Corporation and one HXL-H column manufactured by Tosoh Corporation were connected. Mobile phase solvent: tetrahydrofuran Flow rate: 1.0 mL / min Column temperature: 40°C

[0109] [Solid content] The mass of the aluminum cup (W0) was measured using a precision balance. Next, approximately 1 g of sample was placed in the aluminum cup, and the mass of the sample in the aluminum cup (W1) was measured using a precision balance. The sample in the aluminum cup was heated in an oven at 150°C for 120 minutes, then removed from the oven and returned to room temperature. The residual mass (W2) of the sample in the aluminum cup after heating was measured using a precision balance. The solid content was then calculated using the formula (W2 - W0) / (W1 - W0) × 100 (%).

[0110] [Acid Value] The term "acid value" refers to the acid value per 1 g of the solid content of the resin (A), and was determined by potentiometric titration in accordance with JIS K 0070.

[0111] [Production Example of Resin (A)] [Production Example of (Meth)acrylic Resin (a) (R-1)] A reaction vessel (hereinafter simply referred to as "reaction vessel") equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube was charged with 80 parts of ethyl acetate, 20 parts of methyl methacrylate, 79 parts of n-butyl methacrylate, 1 part of methacrylic acid, and 0.1 parts of 2,2'-azobisisobutyronitrile as an initiator, and the atmosphere inside the reaction vessel was replaced with nitrogen gas. Thereafter, the mixture was heated to 65°C while stirring under a nitrogen atmosphere to initiate the reaction. The reaction solution was then reacted at 65°C for 4 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a solution of acrylic resin (R-1) having a weight average molecular weight (Mw): 35,000, a polydispersity (Mw / Mn): 2, a glass transition temperature (Tg): 35°C, an acid value: 7 mgKOH / g, and a solids content: 25%.

[0112] [Production Examples of (Meth)acrylic Resins (a) (R-2 to R-4)] (Meth)acrylic resins (a) (R-2 to R-4) were produced in the same manner as in the production of (meth)acrylic resin (a) (R-1), except that the compositions and blending amounts (parts by mass) were changed to those shown in Table 1. Note that blank spaces indicate that no blending was performed, and the solid content was 25% in all cases.

[0113]

[0114] The abbreviations in the table are as follows: BA: n-butyl acrylate MMA: methyl methacrylate nBMA: n-butyl methacrylate MAA: methacrylic acid 2HEMA: 2-hydroxyethyl methacrylate GMA: glycidyl methacrylate MOI: 2-methacryloyloxyethyl isocyanate

[0115] [Production Example of Urethane Resin (R-5)] 166 parts of terephthalic acid, 146 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol were charged into a glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and pressure reducing equipment, and the mixture was stirred while passing nitrogen gas through it. The temperature was gradually raised under normal pressure, and the mixture was reacted at 200 to 230°C for approximately 8 hours to obtain a liquid with an acid value of 43 mgKOH / g. Next, 0.01 parts of tetra-n-butoxytitanium was charged, and after nitrogen substitution, the mixture was stirred at 180°C for 30 minutes in a sealed container. The mixture was then reacted at 230°C and 5 mmHg for 2 hours to obtain a polyester diol with an acid value of 1.1 mgKOH / g, a hydroxyl value of 114.2 mgKOH / g, a weight average molecular weight (Mw): 982, and a color of 10 (APHA method, the same applies below). Next, 734 parts of the polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene were charged into a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube, and the mixture was allowed to react for 8 hours at 50°C under a nitrogen atmosphere. 1,200 parts of toluene was added to the mixture to obtain a solution of a urethane prepolymer having an isocyanate group at its terminal. The resulting prepolymer solution was then heated to 70°C, and while maintaining that temperature, a solution containing 20.0 parts of 1,3-diaminopropane, 3.1 parts of benzylamine, 600 parts of 2-propanol, and 961 parts of toluene was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was further reacted at 70°C for 6 hours, thereby obtaining a solution of urethane resin (R-5) having a weight average molecular weight (Mw): 150,000, a dispersity (Mw / Mn): 4.5, a glass transition temperature (Tg): 18°C, an acid value: 10 mgKOH / g, and a solids content: 25%.

[0116] [Production Example of Dispersion of Metal Oxide Particles (B)] [Production Example of Dispersant] A four-necked flask equipped with a stirrer, reflux condenser, gas inlet tube, and thermometer was charged with 60.0 parts of isomyristyl alcohol, 127.8 parts of ε-caprolactone, 112.2 parts of δ-valerolactone, and 0.1 parts of monobutyltin (IV) oxide as a catalyst, and then purged with nitrogen gas. The mixture was reacted with stirring at 120 ° C. for 3 hours. After confirming that 98% had reacted by solid content measurement, 30.5 parts of pyromellitic dianhydride was added, and the reaction was carried out for 5 hours at 100 ° C. After completion of the reaction, the mixture was cooled and the solid content was adjusted with methyl ethyl ketone to obtain a dispersant with a solid content of 81%, an acid value of 49 mg KOH / g, and a linear, acidic dispersant.

[0117] [Production Example of Dispersion (D-1) of Metal Oxide Particles (B)] ZrO ２ (PCS60, manufactured by Nippon Denko Co., Ltd., number average primary particle diameter 20 nm, specific surface area by BET method 50-70 m ２ 724 parts of TiO 2 / g), 80.2 parts of the dispersant, and 1195.8 parts of methyl ethyl ketone were mixed and pre-dispersed using a disper, and then main dispersion was carried out for 2 hours using a 0.6 L Dyno-Mill filled with 1800 g of zirconia beads having a diameter of 0.3 mm. After completion of dispersion, the zirconia beads were removed to obtain a dispersion (D-1) of metal oxide particles (B) having a solid content of 39.4% and a concentration of metal oxide particles (B) of 36.2%. [Production Example of Dispersion (D-2) of Metal Oxide Particles (B)] The metal oxide particles (B) were mixed with TiO 2 ２ (MT-05, manufactured by Teika Co., Ltd., number average primary particle diameter 10 nm, specific surface area by BET method 20-50 m ２ A dispersion (D-2) of metal oxide particles (B) having a solid content of 39.4% and a concentration of metal oxide particles (B) of 36.2% was produced by the same method as in the production of dispersion (D-1) of metal oxide particles (B), except that the dispersant was changed to DISPERBYK (registered trademark)-180 (manufactured by BYK-Chemie, solid content 81%). [Production Example of Dispersion (D-3) of Metal Oxide Particles (B)] A dispersion (D-2) of metal oxide particles (B) having a solid content of 39.4% and a concentration of metal oxide particles (B) of 36.2% was produced by the same method as in the production of dispersion (D-1) of metal oxide particles (B). ２(AEROSIL (registered trademark) 50, manufactured by Nippon Aerosil Co., Ltd., number average primary particle diameter 50 nm, specific surface area by BET method 35 to 65 m ２ A dispersion (D-3) of metal oxide particles (B) having a solid content of 39.4% and a metal oxide particle (B) concentration of 36.2% was produced by the same method as in the production of the dispersion (D-1) of metal oxide particles (B), except that the metal oxide particles (B) was changed to Al. ２ O ３ (AEROXIDE (registered trademark) Alu C, manufactured by Nippon Aerosil Co., Ltd., number average primary particle diameter 13 nm, specific surface area by BET method 85 to 115 m ２ A dispersion (D-4) of metal oxide particles (B) having a solid content of 39.4% and a metal oxide particle (B) concentration of 36.2% was produced by the same method as in the production of dispersion (D-1) of metal oxide particles (B), except that the metal oxide particles (B) was changed to TiO ２ (MT-700B, manufactured by Teika Co., Ltd., number average primary particle diameter 80 nm, specific surface area by BET method 20-60 m ２ A dispersion (D-5) of metal oxide particles (B) having a solid content of 39.4% and a metal oxide particle (B) concentration of 36.2% was produced by the same method as in the production of dispersion (D-1) of metal oxide particles (B), except that the mass ratio of the dispersion (D-1) was changed to 1 / g.

[0118] [Example 1] [Production of Resin Composition] As the resin (A), 314.8 parts of the solution of the aforementioned (meth)acrylic resin (a) (R-1) (78.7 parts of resin (A), 236.1 parts of solvent), 41.4 parts of a dispersion (D-1) of metal oxide particles (B) (16.3 parts of solids (including 15 parts of metal oxide particles (B)), 25.1 parts of solvent), 5 parts of an epoxy-based crosslinking agent jER (registered trademark) YX8034 (manufactured by Mitsubishi Chemical Corporation) as a crosslinking agent as other components, and 55 parts of methyl ethyl ketone as a solvent were sequentially added while stirring with a disper and stirred until sufficiently uniform. Next, the mixture was filtered through a membrane filter with a pore size of 10 μm to remove coarse foreign matter that may cause coating unevenness, and a resin composition with a solids content of 24% was obtained. Note that the amounts of the resin (A), metal oxide particles (B), crosslinking agent, and other components listed in Table 2 are calculated as solids contents.

[0119] [Production of Encapsulating Sheet] The resin composition was applied to the release layer of a 38 μm-thick protective film (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O3; Sq on the release layer side was 0.3 μm) so that the thickness after drying would be 20 μm, and the applied resin composition layer was dried for 3 minutes in a hot air oven at 100° C. Next, the release layer side of a 50 μm-thick release liner (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O1) was attached to the exposed resin composition layer, and aging was performed at 0° C. for 7 days to obtain an encapsulating sheet of Example 1 in which the protective film / 20 μm-thick resin composition layer / release liner were laminated in this order.

[0120] [Thickness Tt of Encapsulating Sheet, Thickness Ta of Resin Composition Layer, Thickness Tb of Protective Film, Thickness Tc of Release Liner] Ten equally spaced positions were determined from one end to the other end in the width direction of the encapsulating sheet cut to a size of 10 cm x 10 cm, the thicknesses of the 10 positions were measured, and the average value was defined as the thickness Tt of the encapsulating sheet. Next, the release liner was peeled from the encapsulating sheet, and the thicknesses of the peeled release liner were measured at 10 positions corresponding to the same positions as above. The average value was defined as Tc. Thereafter, the protective film was further peeled from the resin composition layer, and the thicknesses of the peeled protective film at 10 positions corresponding to the same positions as above were measured. The average value was defined as Tb. The thickness Ta of the resin composition layer was calculated by the following (Equation 2). The thickness was measured using an MH-15M (manufactured by Nikon Corporation). Ta = Tt - Tc - Tb (Equation 2)

[0121] [Tan δ peak strength, tan δ40 of resin composition layer] An encapsulating sheet was produced in the same manner as in the above-described encapsulating sheet production example, except that the thickness of the resin composition layer was changed to 50 μm. The sheet was cut to a size of 0.5 cm x 2 cm, and the protective film and release liner were peeled off. The dynamic viscoelasticity of the obtained resin composition layer was measured using a dynamic viscoelasticity measuring device DVA-200 / L2 (manufactured by IT Measurement and Control Co., Ltd.) at a frequency of 10 Hz, a measurement temperature range of -50 to 150 ° C., a heating rate of 5 ° C. / min, and in tensile mode, and the loss tangent (tan δ) was plotted. The peak top intensity (tan δ peak intensity) of the loss tangent (tan δ) and the loss tangent at 40 ° C. (tan δ40) were read from the obtained graph.

[0122] [Refractive Index] The encapsulating sheet of Example 1 was cut into a size of 2 cm × 5 cm, and the protective film and the release liner were peeled off. The refractive index of the obtained resin composition layer was measured using an Abbe refractometer (DR-M2, Atago Co., Ltd.).

[0123] [Haze and total light transmittance] The encapsulating sheet of Example 1 was cut into a size of 2.5 cm × 10 cm, and a 1.1 mm thick glass plate (blue plate glass, manufactured by Kawamura Kyuzo Shoten Co., Ltd.) was attached to the surface from which the release liner was peeled off, and then the protective film was peeled off. The haze value and total light transmittance of the resin composition layer were measured using a haze meter (NDH8000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0124] [Saturation C ＊ The encapsulating sheet of Example 1 was cut to a size of 2.5 cm x 10 cm, and a glass plate (blue plate glass, manufactured by Kawamura Kuzo Shoten Co., Ltd.) having a thickness of 1.1 mm was attached to the surface from which the release liner was peeled off, and then the sheet was left standing for 120 minutes under a condition of 180°C. The glass plate was placed on a standard white plate so that the glass plate was in contact with the standard white plate, and the protective film was peeled off, thereby producing a configuration of standard white plate / glass plate / resin composition layer. Using a colorimeter (X-Rite eXact, manufactured by X-Rite), the light source conditions were D50 / 2° and a ＊ value and b ＊ The values ​​were measured at three arbitrary points on the surface of the resin composition layer, and the average value was calculated. ＊ The average value and b ＊ Average value of saturation C ＊ was calculated. ＊ = (a ＊２ +b ＊２ ) ０．５ (Formula 1)

[0125] [Root mean square height Sq] The release layer surface of a protective film cut to a size of 10 cm x 10 cm was measured at any five points using a confocal microscope (manufactured by Lasertec, OPTELICS HYBRID+, objective lens 20x) in accordance with ISO 25178, and then the root mean square height Sq was calculated by analyzing the data using data analysis software (LMeye8).

[0126] [Evaluation Method and Criteria] [Embeddability] A test substrate (a 25 mm x 25 mm glass plate on one side of which recesses each having a width of 200 μm, a height of 5 μm, and a width of 200 μm) was prepared, simulating the unevenness of a micro LED substrate. A schematic cross-sectional view of the test substrate is shown in FIG. 3. The encapsulating sheet was cut to a size of 30 mm x 30 mm, the release liner was peeled off to expose the resin composition layer, and the resin composition layer was placed on the surface of the test substrate on which the unevenness was formed. Thereafter, a 50 μm thick TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tocello Co., Ltd.) and a 2.0 mm thick PVC film (Celeb T, manufactured by Okamoto Corporation) were laminated in this order as cushioning materials on the protective film, and cardboard was further laminated to prevent sticking. A laminate consisting of a glass substrate / resin composition layer / protective film / cushioning material (TPX / PVC film) / cardboard was pressed against the substrate surface from above at 5 MPa and 100°C for 20 minutes, filling the recesses of the test substrate with the resin composition layer to form a sealing layer. After pressing, the cushioning material and cardboard were peeled off. The sealing layer that protruded from the sides of the resulting sealing layer-attached test substrate was roughly removed using a cutter, and the sealing layer remaining on the sides of the sealing layer-attached test substrate was further removed by sanding, exposing the side of the test substrate so that the uneven portions could be observed. The embeddability of 15 randomly selected recesses of the test substrate was evaluated by microscopic observation. Grooves were considered embedded when the maximum gap between the sealing layer and the test substrate in the recesses of the test substrate was 1 μm or less. The evaluation criteria were as follows: A to C were considered good, and D was considered to be an evaluation that did not achieve the target performance. A: 14 or more embedded grooves. B: 13 or less embedded grooves, 11 or more embedded grooves. C: 10 or less embedded grooves, 8 or more embedded grooves. D: 7 or less embedded grooves.

[0127] [Seamlessness] One sheet of the encapsulating sheet of Example 1 cut to 25 mm x 100 mm was prepared, the release liner was peeled off to expose the resin composition layer, and the sheet was placed on a glass plate (25 mm x 100 mm x 1.1 mm, blue plate glass, manufactured by Kawamura Hisazo Shoten Co., Ltd.) so that the edges were aligned. Then, a 50 μm thick TPX (Opulent X-44B, manufactured by Mitsui Chemicals Tocello Co., Ltd.) and a 2.0 mm thick PVC film (Celeb T, manufactured by Okamoto Corporation) were laminated in this order on the protective film as cushioning materials, and cardboard was further laminated to prevent sticking. A laminate consisting of glass plate / resin composition layer / protective film / cushioning material (TPX / PVC film) / cardboard was pressed against the substrate surface from above at 5 MPa and 100 ° C. for 20 minutes, bonding the glass plate and the resin composition layer, and forming a sealing layer on the glass plate. After pressing, the cushioning material and cardboard were peeled off to obtain a seamless test piece. The protective film was peeled off from the obtained seamless test piece, and the haze (Hs) was measured. Next, two sheets of the encapsulating sheet were prepared by cutting them into a size of 25 mm in length and 50 mm in width. The release film was peeled off to expose the resin composition layer, and the sheets were placed side by side on a glass plate (25 mm x 100 mm x 1.1 mm, blue plate glass, manufactured by Kawamura Kuzo Shoten Co., Ltd.) with the edges aligned. Thereafter, the sheets were pressed in the same manner as the seamless test piece to obtain a joint test piece in which the interface between the encapsulating layers formed from the two encapsulating sheets was the seam. The protective film was peeled off from the joint test piece, and the haze (Hj) at the seam was measured. The change (|Hs-Hj| / 100(%)) between the haze (Hs) of the seamless test piece and the haze (Hj) of the joint test piece was calculated and evaluated. The evaluation criteria were as follows, with A to C being good, and D being an evaluation of not achieving the target performance. A: The change was 0.5% or less. B: The amount of change is more than 0.5% and 0.8% or less. C: The amount of change is more than 0.8% and 1.0% or less. D: The amount of change is more than 1.0%.

[0128] [Adhesion] A seamless test piece used for seamlessness evaluation was prepared, the protective film was peeled off, and the test piece consisting of a glass plate and a sealing layer was left standing at 180 °C for 120 minutes to produce a test piece in which the glass plate and the sealing layer were adhered to each other. In accordance with JIS K 5600-5-6 (cross-cut method), a 1 mm square right-angle grid pattern (25 squares) was created on the sealing layer of the test piece using a cross-cut guide and a cutter knife, and adhesive tape (CT1835, manufactured by Nichiban Co., Ltd.) was applied to the grid-cut portion and firmly adhered to the sealing layer. Within 5 minutes of adhesion, the tape was peeled off at an angle close to 60 ° for 0.5 to 1.0 seconds. The state of the peeled sealing layer was observed to evaluate adhesion. The evaluation criteria were as follows, with A to C being good and D being an evaluation that did not achieve the target performance. A: 0 squares were completely peeled, and there was no partial peeling only at the end of the cut. B: 0 squares completely peeled off, partial peeling only at the edges of the cuts. C: 1 to 2 squares peeled off. D: 3 or more squares peeled off.

[0129] [Visibility] A seamless test specimen used for seamlessness evaluation was prepared, the protective film was peeled off, and the test specimen consisting of a glass plate and a sealing layer was left standing at 180°C for 120 minutes to produce a test specimen in which the glass plate and the sealing layer were closely attached. The test specimen was placed on the display surface of an LED display device (LED Name Badge (white), manufactured by Asco Corporation) so that the sealing layer was in contact with the display surface, producing a laminate consisting of a display device / sealing layer / glass plate. Next, white letters (a total of three capital letters, A to C) were displayed on a black background on the display device. An observer observed the displayed letters from two angles: an angle 30° above the horizontal and a vertical angle 90° above the horizontal. The observer visually compared and evaluated the distortion of the displayed letters and the blurring of the outlines before and after placing the test specimen. The evaluation criteria were as follows, with A to B being considered good and D being considered failure to achieve the target performance. A: No distortion or blurring of the outlines was observed under any angle conditions. B: Distortion and / or blurring of the outline is observed under any one of the angle conditions. D: Distortion and / or blurring of the outline is observed under all angle conditions.

[0130] [Examples 2 to 37], [Comparative Examples 1 to 10] Encapsulating sheets were prepared in the same manner as in Example 1, except that the content, thickness Ta, and protective film were changed as shown in Tables 2 to 5, and evaluated in the same manner. Note that any crosslinking agent, oligomer, monomer, polymerization initiator, and other components were also added at the same time. In Tables 2 to 5, the amounts of resin (A), crosslinking agent, oligomer, monomer, polymerization initiator, and other components are calculated as solid content. The amount of metal oxide particles (B) is calculated as the amount of the dispersions (D-1 to D-5) calculated as solid content, and the amount of metal oxide particles (B) in the dispersions (D-1 to D-5) is shown in parentheses. Blank spaces indicate that no compound was added.

[0131] The abbreviations in the table are as follows: C-1: Epoxy crosslinking agent (jER (registered trademark) YX8034, hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation) C-2: Isocyanate compound (Cosmonate (registered trademark) T100, 2,4-tolylene diisocyanate, manufactured by Mitsui Fine Chemicals, Inc.) C-3: Silane coupling agent (KBE-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Silicones Co., Ltd.) O-1: Urethane acrylate oligomer (KRM8667, manufactured by Daicel Allnex Corporation, trifunctional, weight average molecular weight 2000, viscosity at 60°C 11,000 cps) O-2: Epoxy acrylate oligomer (Miramer (registered trademark) HR6042, manufactured by MIWON Corporation, bifunctional, weight average molecular weight 1400, viscosity at 25°C 21,000 cps) O-3: Polyester acrylate oligomer (Miramer (registered trademark) PS4040, manufactured by MIWON Corporation, tetrafunctional, weight average molecular weight 1300, viscosity at 25°C 6,300 cps) O-4: Acrylic ester oligomer (ART CURE (registered trademark) UN-9000PEP, manufactured by Negami Chemical Industrial Co., Ltd., bifunctional, weight average molecular weight 5000, viscosity at 25°C 2,000,000 cps) M-1: EO-modified (3) trimethylolpropane triacrylate (Miramer (registered trademark) M3130, manufactured by MIWON Corporation, trifunctional, viscosity at 25°C 65 cps) M-2: 1,6-hexanediol diacrylate (Viscoat (registered trademark) #230, manufactured by Osaka Organic Chemical Industry Ltd., bifunctional, viscosity at 25°C 7 cps) I-1: Di-t-butyl peroxide (Perbutyl (registered trademark) D, NOF Corporation) I-2: 2,2'-azobis(N-butyl-2-methylpropionamide) (VAm-110, Fujifilm Wako Pure Chemical Industries, Ltd.) A-1: ​​Phosphorus-based antioxidant (ADEKA STAB PEP-36, ADEKA Corporation) A-2: Surface conditioner (BYK (registered trademark) -3440, BYK-Chemie) P-1: 38 μm thick protective film (SP-PET-O3, Mitsui Chemicals Tohcello, Inc., Sq: 0.3 μm) P-2: 75 μm thick protective film (Matte film (Type M3), IM Corporation, Sq: 1.5 μm) P-3: 50 μm thick protective film (Matte film (Type M8), IM Corporation, Sq: 1,0 μm) P-4: 10 μm thick protective film (matte film (type M3), manufactured by IM Co., Ltd., Sq: 1.5 μm) P-5: 100 μm thick protective film (matte film (type M8), manufactured by IM Co., Ltd., Sq: 1.0 μm) P-6: 188 μm thick protective film (matte film (type M3), manufactured by IM Co., Ltd., Sq: 1.5 μm) P-7: 200 μm thick protective film (matte film (type M2), manufactured by IM Co., Ltd., Sq: 2.0 μm),

[0132]

[0133]

[0134]

[0135]

[0136] In the present disclosure, in the case of an encapsulating sheet that does not contain metal oxide particles (B) having a number-average primary particle diameter of 5 to 50 nm, issues with embeddability, adhesion, or visibility are observed, as shown in Comparative Examples 1, 5, 6, and 10. Furthermore, in the case of an encapsulating sheet having a refractive index outside the range of 1.45 to 1.65, issues with seamlessness and visibility are observed, as shown in Comparative Examples 2 to 4 and 7 to 9. The encapsulating sheets of Comparative Examples 1 to 10 were unable to achieve a high level of embeddability and seamlessness in a balanced manner. Furthermore, they were unable to achieve high levels of adhesion and visibility. In contrast, according to Examples 1 to 37, the encapsulating sheets of the present disclosure exhibited excellent embeddability and excellent seamlessness, as shown in Tables 2 to 5. Furthermore, because of their excellent adhesion and visibility, it was found that the encapsulating sheets of the present disclosure can be used effectively to encapsulate optical semiconductor elements.

[0137] This application claims priority based on Japanese Patent Application No. 2023-135317, filed August 23, 2023, and Japanese Patent Application No. 2023-173435, filed October 5, 2023, the disclosures of which are incorporated herein in their entireties.

[0138] DESCRIPTION OF SYMBOLS 1: Encapsulating sheet 2: Resin composition layer 2': Encapsulating layer 3: Base material 4: Release liner 5: Optical semiconductor element 6: Substrate 7: Glass substrate

Claims

1. An encapsulating sheet for encapsulating an optical semiconductor element, comprising: a protective film and a resin composition layer arranged in this order; the resin composition layer contains 5.3 to 48.2 parts by mass of metal oxide particles (B) per 100 parts by mass in total of resin (A), monomer and oligomer; the number average primary particle diameter of the metal oxide particles (B) is 5 to 50 nm; and the refractive index of the resin composition layer is 1.45 to 1.

65.

2. The sealing sheet according to claim 1, wherein the metal constituting the metal oxide particles (B) includes at least one metal selected from the group consisting of Ti, Al and Zr.

3. The encapsulating sheet according to claim 1, wherein the resin (A) contains at least one resin selected from the group consisting of (meth)acrylic resins (a) and urethane resins (b).

4. The resin composition layer has a haze of 12% or less and a total light transmittance of 80% or more, ＊ a ＊ b ＊ Saturation C determined from color space ＊ The encapsulating sheet according to claim 1, wherein the Mn content is 0 to 10.

5. The encapsulating sheet according to claim 1, wherein the resin composition layer has a thickness Ta of 1 to 100 μm, and the protective film has a thickness Tb of 10 to 188 μm.

6. The encapsulating sheet according to claim 5, wherein the protective film and the resin composition layer are directly laminated together, and the ratio of the root mean square height Sq defined in ISO 25178 on the surface of the protective film in contact with the resin composition layer to the thickness Ta of the resin composition layer is 0.01 to 30%.

7. The encapsulating sheet according to any one of claims 1 to 6, wherein the loss tangent of the resin composition layer obtained by dynamic viscoelasticity measurement has a peak top strength (tan δ peak strength) of 0.6 to 2.2 in the range of -50 to 80°C.

8. The encapsulating sheet according to claim 7, wherein the optical semiconductor element is a micro LED.

9. A display having a sealing layer containing 5.3 to 48.2 parts by mass of metal oxide particles (B) having a number average primary particle diameter of 5 to 50 nm per 100 parts by mass of the total of resin (A), monomer and oligomer, and having a refractive index of 1.45 to 1.65.

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