Encapsulant composition, dry film, cured product, and encapsulated structure

Abstract

To provide a sealing material composition which facilitates detection of defects when being coated onto a transparent film, exhibits good transparency after various components are sealed, and suppresses coloring.SOLUTION: A sealing material composition contains an epoxy resin, an organic solvent and dicyandiamide, in which in a resin film having a thickness of 50 μm formed from the composition, all transmittances at a light wavelength of 400 nm to 800 nm are 75% or less, and in a cured film having a thickness of 50 μm formed from the composition, all transmittances at a light wavelength of 400 nm to 800 nm are 85% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an encapsulant composition, a dry film, a cured product, and an encapsulated structure. [Background technology]

[0002] BACKGROUND ART Transparent curable encapsulant compositions have been used to protect optical components, light-emitting components, and the like (for example, Patent Documents 1 and 2).

[0003] However, because conventional transparent encapsulant compositions are transparent, it is not easy to detect defects during coating, and it has been particularly difficult to detect defects such as sink marks and craters that occur when coating on a transparent film such as a PET film.

[0004] It is conceivable to color the composition to make it easier to detect defects during application, but such a colored encapsulant composition would not function as a transparent encapsulant, and would be disadvantageous as an encapsulant for optical components or light-emitting components, for example.

[0005] Similarly, coloration of the transparent encapsulant composition due to heat curing is also undesirable. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 8-283385 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-42762 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide an encapsulant composition that allows easy detection of defects when applied to a transparent film, and that exhibits good transparency and suppressed coloration after sealing various parts; a dry film having a resin layer obtained from the composition; a cured product of the composition or the resin layer of the dry film; and an encapsulating structure having the cured product.

[0008] Another object of the present invention is to provide an encapsulant composition that exhibits good transparency and suppresses coloration after sealing various parts, a dry film having a resin layer obtained from the composition, a cured product of the composition or the resin layer of the dry film, and an encapsulated structure having the cured product. [Means for solving the problem]

[0009] As a result of extensive research into achieving the above object, the inventors have discovered that the above problem can be solved by blending an epoxy resin, an organic solvent, and dicyandiamide, and adjusting the transmittance of the light wavelength of the resin film before curing and the light wavelength of the cured film after curing to specific ranges, thereby completing the present invention.

[0010] That is, the encapsulant composition of the present invention is an encapsulant composition containing an epoxy resin, an organic solvent, and dicyandiamide, characterized in that a 50 μm-thick resin film formed from the composition has a transmittance of 75% or less at light wavelengths of 400 nm to 800 nm, and a 50 μm-thick cured film formed from the composition has a transmittance of 85% or more at light wavelengths of 400 nm to 800 nm.

[0011] In the encapsulant composition of the present invention, the epoxy resin preferably contains an epoxy resin having an alicyclic skeleton.

[0012] In the encapsulant composition of the present invention, the epoxy resin preferably contains a liquid epoxy resin.

[0013] The dry film of the present invention is characterized by having a resin layer obtained by applying the above-mentioned sealing material composition onto a film and drying it.

[0014] The cured product of the present invention is characterized by being obtained by curing the encapsulant composition or the resin layer of the dry film.

[0015] The sealing structure of the present invention is characterized by comprising the above-described cured product.

[0016] Furthermore, as a result of extensive research into achieving the other object described above, the present inventors have found that the above-mentioned problems can be solved by blending an alicyclic epoxy resin, an organic solvent, a curing agent, and a certain amount or more of a thermoplastic resin, and by controlling the transmittance of light wavelengths and haze of the cured film after curing to specific ranges, thereby completing the present invention.

[0017] That is, another encapsulant composition of the present invention is an encapsulant composition containing an epoxy resin having an alicyclic skeleton, an organic solvent, a curing agent, and a thermoplastic resin, wherein the thermoplastic resin accounts for 20 mass% or more of the total solid content of the composition, and a cured film having a thickness of 50 μm formed from the composition has a transmittance of 85% or more at light wavelengths of 400 nm to 800 nm and a haze of 10% or less.

[0018] Another dry film of the present invention is characterized by having a resin layer obtained by applying the encapsulant composition onto a film and drying it. Another cured product of the present invention is characterized by being obtained by curing the encapsulant composition or the resin layer of the dry film. Another encapsulating structure of the present invention is characterized by having the cured product. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide an encapsulant composition that allows easy detection of defects when applied to a transparent film, and that exhibits good transparency after sealing various components and suppresses coloration; a dry film having a resin layer obtained from the composition; a cured product of the composition or the resin layer of the dry film; and an encapsulating structure having the cured product.

[0020] Furthermore, according to the present invention, it is possible to provide an encapsulant composition that exhibits good transparency and suppresses coloration after encapsulating various components, a dry film having a resin layer obtained from the composition, a cured product of the composition or the resin layer of the dry film, and an encapsulated structure having the cured product. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a graph showing the transmittance after curing of the thermosetting resin composition of Example 3. The horizontal axis represents the light wavelength (nm), and the vertical axis represents the transmittance (%). [Figure 2] 1 is a graph showing the transmittance after curing of the thermosetting resin composition of Comparative Example 1. The horizontal axis represents the light wavelength (nm), and the vertical axis represents the transmittance (%). DETAILED DESCRIPTION OF THE INVENTION

[0022] The encapsulant composition of the present invention is an encapsulant composition containing an epoxy resin, an organic solvent, and dicyandiamide, characterized in that a 50 μm-thick resin film formed from the composition has a transmittance of 75% or less at light wavelengths of 400 nm to 800 nm, and a 50 μm-thick cured film formed from the composition has a transmittance of 85% or more at light wavelengths of 400 nm to 800 nm.

[0023] The encapsulant composition of the present invention has a resin film with low transmittance at light wavelengths before curing, making it easy to detect defects during application, while the cured film has high transmittance at light wavelengths and excellent transparency after curing. These properties are attributed to dicyandiamide, and even though the composition becomes cloudy due to the inclusion of dicyandiamide before curing and has low transmittance at light wavelengths, a transparent cured film with excellent transmittance can be obtained after thermal curing. Furthermore, while compositions containing epoxy resins are prone to discoloration upon thermal curing, the cured product of the present invention is less likely to discolor.

[0024] The organic solvent preferably does not contain an organic solvent that dissolves dicyandiamide, and for example, it is desirable that it does not contain an amide-based solvent such as DMF.

[0025] Each component of the sealing resin composition of the present invention will be described in detail below.

[0026] [Epoxy resin] The encapsulant composition of the present invention contains an epoxy resin. The epoxy resin is a resin containing epoxy groups, and any conventionally known epoxy resin can be used. Examples include bifunctional epoxy resins having two epoxy groups per molecule and multifunctional epoxy resins having three or more epoxy groups per molecule. The epoxy resin may be a solid epoxy resin, a semi-solid epoxy resin, or a liquid epoxy resin. Liquid epoxy resins are preferred for slitting dry films. In this specification, "solid epoxy resin" refers to an epoxy resin that is solid at 40°C, "semi-solid epoxy resin" refers to an epoxy resin that is solid at 20°C and liquid at 40°C, and "liquid epoxy resin" refers to an epoxy resin that is liquid at 20°C. The liquid state is determined in accordance with the "Method for Confirming Liquid State" in Appendix 2 of the Ministerial Ordinance on the Testing and Properties of Hazardous Materials (Ministry of Home Affairs Ordinance No. 1 of 1989). For example, the method described in paragraphs 23 to 25 of JP 2016-079384 A can be used.

[0027] Examples of liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, glycidylamine type epoxy resins, aminophenol type epoxy resins, and alicyclic epoxy resins.

[0028] Among epoxy resins, it is preferable to contain an epoxy resin having an alicyclic skeleton, as this further suppresses coloration and allows for the production of a more transparent cured product. It is more preferable for the solid epoxy resin to contain a solid epoxy resin having an alicyclic skeleton. The epoxy resin having an alicyclic skeleton may be, for example, a hydrogenated epoxy resin of an epoxy resin having an aromatic ring, such as a bisphenol A epoxy resin. Examples of the alicyclic skeleton include a cyclopentane ring, a dicyclopentane ring, and a cyclohexane ring. Examples of epoxy resins having an alicyclic skeleton include ST-6100 manufactured by Nippon Steel Chemical & Material Co., Ltd. and YX8000 manufactured by Mitsubishi Chemical Corporation.

[0029] The epoxy resin may be used alone or in combination of two or more. The amount of the epoxy resin blended is preferably 50 to 98 mass % of the total solid content of the composition.

[0030] In the present invention, the amount of the epoxy resin having an alicyclic skeleton is preferably 30 to 98 mass %, more preferably 35 to 98 mass %, of the total solid content of the composition.

[0031] [Organic solvents] The sealant composition of the present invention contains an organic solvent. Examples of the organic solvent include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. Specific examples of the organic solvent include ketones such as methyl ethyl ketone, cyclohexanone, methyl butyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, and acetic acid. Examples of suitable solvents include esters such as isobutyl acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, 2-methoxypropanol, n-butanol, isobutyl alcohol, isopentyl alcohol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha, as well as tetrachloroethylene and turpentine. Organic solvents that may be used include Swazol 1000 and Swazol 1500 manufactured by Maruzen Petrochemical Co., Ltd., Solvent #100 and Solvent #150 manufactured by Sankyo Chemical Co., Ltd., Shellsol A100 and Shellsol A150 manufactured by Shell Chemicals Japan, and Ipzol 100 and Ipzol 150 manufactured by Idemitsu Kosan Co., Ltd. Among the organic solvents, it is preferable to contain at least one of cyclohexanone, methyl ethyl ketone, and propylene glycol monomethyl ether acetate. The organic solvents may be used alone or as a mixture of two or more.

[0032] The amount of the organic solvent blended is preferably 30 to 70% by mass of the composition.

[0033] [Dicyandiamide] The encapsulant composition of the present invention contains dicyandiamide as a curing agent, and the blending amount of dicyandiamide is preferably 1 to 5 mass % of the total solid content of the composition.

[0034] (curing accelerator) The encapsulant composition of the present invention may contain a curing accelerator. The curing accelerator accelerates the thermosetting reaction and is used to further improve properties such as adhesion, chemical resistance, and heat resistance. Specific examples of the curing accelerator include imidazole and its derivatives; guanamines such as acetoguanamine and benzoguanamine; polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylenediamine, diaminodiphenylsulfone, urea, urea derivatives, melamine, and polybasic hydrazides; organic acid salts and / or epoxy adducts thereof; amine complexes of boron trifluoride; triazine derivatives such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, and 2,4-diamino-6-xylyl-S-triazine; and tertiary amines such as trimethylamine, triethanolamine, N,N-dimethyloctylamine, N-benzyldimethylamine, pyridine, 4-dimethylaminopyridine, N-methylmorpholine, hexa(N-methyl)melamine, 2,4,6-tris(dimethylaminophenol), and tetramethylguanidine. Examples of the curing accelerator include imidazole and its derivatives.

[0035] The curing accelerator can be used alone or in combination of two or more. When it is particularly desired to accelerate curing, it can be used in an amount of preferably 0.01 to 10 parts by mass per 100 parts by mass of the epoxy resin.

[0036] (hardening agent) The encapsulant composition of the present invention may contain a curing agent other than dicyandiamide. Examples of such a curing agent include a compound having a phenolic hydroxyl group, an acid anhydride, and a compound having a thiol group. The curing agent may be used alone or in combination of two or more.

[0037] Examples of the compound having a phenolic hydroxyl group that can be used include conventionally known compounds such as phenol novolac resins, alkylphenol novolac resins, bisphenol A novolac resins, dicyclopentadiene-type phenolic resins, Xylok-type phenolic resins, terpene-modified phenolic resins, cresol / naphthol resins, polyvinylphenols, phenol / naphthol resins, α-naphthol skeleton-containing phenolic resins, triazine skeleton-containing cresol novolac resins, biphenylaralkyl-type phenolic resins, and Xylok-type phenolic novolac resins. Examples of the resin having a phenolic hydroxyl group include phenol novolac resin (HF-4M, manufactured by Meiwa Chemical Industry Co., Ltd.), Zyloc type phenol novolac resin (MEH-7800, manufactured by Meiwa Chemical Industry Co., Ltd.), and biphenyl aralkyl type novolac resin (MEH-7851, manufactured by Meiwa Chemical Industry Co., Ltd.).

[0038] Examples of the acid anhydride include alicyclic dibasic acid anhydrides such as methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, Nadic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, and tetrabromophthalic anhydride; aliphatic or aromatic dibasic acid anhydrides such as succinic anhydride, maleic anhydride, itaconic anhydride, octenylsuccinic anhydride, pentadodecenylsuccinic anhydride, phthalic anhydride, and trimellitic anhydride; and aliphatic or aromatic tetrabasic acid dianhydrides such as biphenyltetracarboxylic dianhydride, diphenylethertetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride.

[0039] The compound having a thiol group is a compound having two or more thiol groups in one molecule. Any conventionally known compound having a thiol group can be used. Examples of the compound having a thiol group include TMMP (trimethylolpropane tris(3-mercaptopropionate)), PEMP (pentaerythritol tetrakis(3-mercaptopropionate)), and DPMP (dipentaerythritol hexaneth(3-mercaptopropionate).

[0040] The blending amount of the curing agent other than dicyandiamide is preferably 1 to 20 mass % of the total solid content of the composition.

[0041] (thermoplastic resin) The encapsulant composition of the present invention may further contain a thermoplastic resin to facilitate the production of a dry film having a thick resin layer. Examples of the thermoplastic resin include thermoplastic polyhydroxypolyether resins, phenoxy resins, which are condensates of epichlorohydrin and various bifunctional phenolic compounds, or phenoxy resins in which the hydroxyl groups of the hydroxyether moieties present in the skeleton are esterified using various acid anhydrides or acid chlorides, polyvinyl acetal resins, polyamide resins, polyamideimide resins, block copolymers, and polymer resins having a glass transition temperature of 20°C or lower and a weight-average molecular weight of 10,000 or higher. The thermoplastic resins may be used alone or in combination of two or more. The thermoplastic resin is preferably phenoxy resin.

[0042] Specific examples of phenoxy resins include FX280 and FX293 manufactured by Nippon Steel Chemical & Material Co., Ltd., and YX8100, YX6954, YL6954, and YL6974 manufactured by Mitsubishi Chemical Corporation. Specific examples of polyvinyl acetal resins include the S-LEC KS series manufactured by Sekisui Chemical Co., Ltd., polyamide resins include the KS5000 series manufactured by Hitachi Chemical Co., Ltd. and the BP series manufactured by Nippon Kayaku Co., Ltd., and polyamide-imide resins include the KS9000 series manufactured by Hitachi Chemical Co., Ltd.

[0043] The amount of the thermoplastic resin is preferably 1 to 70% by mass, more preferably 20 to 50% by mass, based on the total solid content of the composition. From the viewpoint of reducing haze after curing, the amount is preferably 20% by mass or more, more preferably 40% by mass or more, based on the total solid content of the composition.

[0044] (Other ingredients) The encapsulant composition of the present invention may contain an acrylic, fluorine-based, or silicone-based antifoaming agent, leveling agent, or surface conditioner to the extent that coloration of the cured product can be suppressed. Examples include the BYK series, such as BYK-3550 manufactured by BYK Japan. The amount of these additives added is preferably 0.01 to 1.5 mass% of the total solid content of the composition. The encapsulant composition of the present invention may further contain, as necessary, conventionally known additives such as antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, surfactants, plasticizers, lubricants, flow modifiers, thickeners, film-forming agents, adhesion promoters, mold release agents, polymerization initiators, sensitizers, organic fillers, inorganic fillers, rubber-like particles, ion adsorbents, and reactive diluents.

[0045] In a resin film having a thickness of 50 μm formed from the encapsulant composition of the present invention, the transmittance for light having wavelengths of 400 nm to 800 nm is 75% or less.

[0046] In a 50 μm thick cured film formed from the encapsulant composition of the present invention, the transmittance at light wavelengths of 400 nm to 800 nm is 85% or higher, preferably 90% or higher, and more preferably 93% or higher. In addition, in a 50 μm thick cured film, the difference in transmittance at wavelengths of 400, 500, and 600 nm is preferably less than 6%, more preferably 5% or less. When the difference in transmittance is less than 6%, the color tone is particularly excellent and coloring is suppressed.

[0047] In a resin film having a thickness of 50 μm formed from the encapsulant composition of the present invention, the haze is preferably 20% or more, more preferably 25% or more.

[0048] In a cured film having a thickness of 50 μm formed from the encapsulant composition of the present invention, the haze is preferably 10% or less, and more preferably 5% or less.

[0049] The encapsulant composition of the present invention may be used in the form of a dry film or in a liquid form. When used in a liquid form, it may be a one-component or two-component or more-component composition, but is preferably a two-component or more-component composition from the viewpoint of storage stability.

[0050] The dry film of the present invention can be produced by applying the encapsulant composition of the present invention to a carrier film and drying it to form a resin layer as a dried coating film. If necessary, a protective film can be laminated on the resin layer.

[0051] The carrier film serves to support the resin layer of the dry film and is a film onto which the encapsulant composition is applied when the resin layer is formed. Examples of the carrier film include polyester films such as polyethylene terephthalate and polyethylene naphthalate, films made of thermoplastic resins such as polyimide films, polyamideimide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, and polystyrene films, and surface-treated paper. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, and ease of handling. The thickness of the carrier film is not particularly limited, but is appropriately selected from the range of approximately 10 to 150 μm depending on the application. The surface of the carrier film on which the resin layer is to be formed may be subjected to a release treatment. Furthermore, sputtering or ultrathin copper foil may be formed on the surface of the carrier film on which the resin layer is to be formed.

[0052] The protective film is provided on the side of the resin layer opposite the carrier film for the purposes of preventing dust and the like from adhering to the surface of the resin layer of the dry film and improving handleability. Examples of the protective film that can be used include films made of thermoplastic resins such as those exemplified for the carrier film, and surface-treated paper. Among these, polyester film, polyethylene film, and polypropylene film are preferred. The thickness of the protective film is not particularly limited, but is appropriately selected depending on the application within the range of approximately 10 to 150 μm. The surface of the protective film on which the resin layer is provided may be subjected to a release treatment.

[0053] In the present invention, the encapsulant composition may be applied to the cover film and dried to form a resin layer, and then a carrier film may be laminated on the surface of the resin layer. That is, in the present invention, either a carrier film or a cover film may be used as the film to which the encapsulant composition is applied when producing a dry film.

[0054] The dry film of the present invention is not particularly limited as long as it has a resin layer obtained by applying the encapsulant composition of the present invention to a film and drying it. The dry film may be formed by laminating two or more resin layers of two or more dry films. The dry film may also have a resin layer of the dry film of the present invention and a resin layer of another composition. It is difficult to form a uniformly thick resin layer by forming a resin layer by application and drying, but laminating resin layers to form a thick film makes it easy to form a uniformly thick resin layer. A thick resin layer can provide sufficient encapsulation even when the light-emitting element to be encapsulated is thick.

[0055] A conventionally known method may be used to produce a sealed structure using the sealant composition of the present invention. For example, in the case of a three-layer dry film in which a resin layer is sandwiched between a carrier film and a protective film, a sealed structure can be produced by the following method. Either the carrier film or the protective film is peeled from the dry film, and the dry film is heat-laminated onto a substrate on which an object to be sealed, such as an optical component or a light-emitting component, is mounted, followed by thermal curing. The thermal curing may be performed in an oven or by hot plate pressing.

[0056] The encapsulant composition of the present invention can be preferably used for encapsulating optical components and light-emitting components. Examples of light-emitting components include light-emitting devices such as LEDs and organic EL devices. In particular, the encapsulant composition can be preferably used for encapsulating LEDs. The light-emitting color of the light-emitting component is not particularly limited, and examples include red, green, and blue. Furthermore, light-emitting devices of multiple different colors may be encapsulated together.

[0057] Another encapsulant composition of the present invention is an encapsulant composition containing an epoxy resin having an alicyclic skeleton, an organic solvent, a curing agent, and a thermoplastic resin, wherein the thermoplastic resin accounts for 20 mass% or more of the total solid content of the composition, and a 50 μm-thick cured film formed from the composition has a transmittance of 85% or more at light wavelengths of 400 nm to 800 nm and a haze of 10% or less. Compositions containing epoxy resins tend to become discolored upon curing, but by blending an epoxy resin having an alicyclic skeleton as the epoxy resin and blending a thermoplastic resin in an amount of 20 mass% or more of the total solid content, it is possible to form a transparent cured product with reduced discoloration.

[0058] The epoxy resin having an alicyclic skeleton is the same as described above. In the other encapsulant composition of the present invention, the amount of the epoxy resin having an alicyclic skeleton blended is preferably 30 to 98 mass %, more preferably 35 to 98 mass %, of the total solid content of the composition. Other epoxy resins may be contained within a range that does not impair the effects of the invention.

[0059] The organic solvent is the same as above. In the other sealing material composition of the present invention, the blending amount of the organic solvent is preferably 30 to 70 mass % in the composition.

[0060] The curing agent is the same as described above. Dicyandiamide is preferably contained as the curing agent, which makes it easier to detect defects when coating on a transparent film. In the other encapsulant composition of the present invention, the blending amount of the curing agent is preferably 1 to 5 mass% of the total solid content of the composition, more preferably 1 to 3 mass%. Dicyandiamide is preferably contained as the curing agent, which makes it easier to detect defects when coating on a transparent film. Note that phenolic curing agents and imidazole compounds tend to discolor the cured product, so their blending amount is preferably small. For example, in the case of a phenolic curing agent, it is preferably 20 mass% or less of the total solid content of the composition. In the case of an imidazole compound, it is preferably 2 mass% or less of the total solid content of the composition.

[0061] The thermoplastic resin is the same as above. In another encapsulant composition of the present invention, the blending amount of the thermoplastic resin is 20 mass % or more, preferably 25 mass % or more, more preferably 40 mass % or more, based on the total solid content of the composition. The thermoplastic resin is preferably a phenoxy resin.

[0062] The other components that can be contained in the encapsulant composition of the present invention are the same as those in the encapsulant composition of the present invention described above.

[0063] In a 50 μm thick cured film formed from another encapsulant composition of the present invention, the transmittance at light wavelengths of 400 nm to 800 nm is 85% or higher, preferably 90% or higher, and more preferably 93% or higher.

[0064] In a cured film having a thickness of 50 μm formed from another encapsulant composition of the present invention, the haze is 10% or less, preferably 5% or less, and more preferably 3% or less.

[0065] The other encapsulant composition of the present invention may be used in the form of a dry film or in liquid form, as described above. When used in liquid form, it may be a one-component or two-component or more, but is preferably two-component or more from the viewpoint of storage stability. The dry film formation is the same as described above. The method for producing the encapsulated structure and suitable uses are also the same as described above. [Example]

[0066] The present invention will be specifically explained below with reference to examples, comparative examples, and test examples of the present invention, but it goes without saying that the present invention is not limited to the following examples. Note that all parts are in parts by mass unless otherwise specified.

[0067] (Examples 1 to 4 and Comparative Examples 1 to 3) The components were mixed according to the formulation shown in Table 1 below and dispersed using a triple roll mill to obtain thermosetting resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3 as encapsulant compositions.

[0068] <Dry film preparation> The resulting thermosetting resin composition was applied to a carrier film (PET film; Toyobo Co., Ltd. TN-200, 38 μm thick, 30 cm × 30 cm) using a bar coater so that the resin layer would have a thickness of 50 μm after drying. The composition was then dried in a hot air circulation oven at 70 to 120°C (average 100°C) for 5 to 10 minutes so that the residual solvent in the resin layer was 0.5 to 2.5% by mass, forming a resin layer on the carrier film. A biaxially oriented polypropylene film (Alphan FG-201, Fish Eyeless, Oji F-Tex Co., Ltd.) was then laminated to the surface of the dry film using a roll laminator set at 80°C to produce a three-layer dry film.

[0069] <Creating an evaluation board> The protective film was removed from the resulting three-layer dry film, and the film was laminated onto a 1 mm thick glass slide using a vacuum laminator MVLP-500 (manufactured by Meiki Seisakusho Co., Ltd.). The lamination conditions were a lamination temperature of 50-80°C and a pressure of 0.3 MPa. The carrier film was then removed, and the resin layer was cured in a hot air circulating drying oven under the conditions of 100°C x 30 min + 150°C x 60 min. <Transmittance> The transmittance of the resin compositions formed on the glass slide before and after curing was measured at 400 to 800 nm using a UV-Visible-Near-Infrared Spectrophotometer V-700 (manufactured by JASCO Corporation). The 50 μm-thick resin films formed from the resin compositions of Examples 1 to 4 all had a transmittance of 75% or less before curing, and 85% or more after curing. A graph of the transmittance after curing in Example 3 is shown in Figure 1. A graph of the transmittance after curing in Comparative Example 1 is shown in Figure 2. <Haze measurement> The resin composition formed on the glass slide before curing and the resin composition after curing were measured using a Hazemeter NDH7000II (manufactured by Nippon Denshoku Industries Co., Ltd.). <Checking the color tone of the cured film> The difference in transmittance at the measured wavelengths of 400, 500, and 600 nm was calculated, and the presence or absence of coloration was confirmed from this difference. Calculation formula: Maximum transmittance - Minimum transmittance = transmittance difference The judging criteria are as follows: ○: The difference is less than 6%. ×: Difference is 6% or more.

[0070] <Checking for defects when producing dry film> After drying, the resin layer was placed on a light table and the surface was visually inspected using transmitted light to check for holes and craters. The evaluation criteria were as follows: 〇: It is easy to check for holes and craters. ×: Missing or crater difficult to confirm.

[0071] [Table 1]

[0072] *1: Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation) *2: Hydrogenated bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation) *3: Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation) *4: Hydrogenated bisphenol A epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.) *5: Phenol novolac epoxy resin (DIC Corporation) *6: Phenoxy resin (Mitsubishi Chemical Corporation) (solid content 30% by mass, cyclohexanone 35% by mass, methyl ethyl ketone 35% by mass) *7: Dicyandiamide (Mitsubishi Chemical Corporation) *8: Phenol novolac resin (manufactured by Meiwa Kasei Co., Ltd.) *9: 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Corporation) *10: N,N-dimethylformamide

[0073] From the results shown in Table 1, it can be seen that the encapsulant compositions of Examples 1 to 4 can produce cured products with excellent transmittance and little coloring after curing. In addition, because the transmittance before curing is low, it is easy to detect defects such as craters, and it is possible to form high-quality dry fills.

Claims

1. A sealing material composition containing an epoxy resin, an organic solvent, and dicyandiamide, the epoxy resin contains a hydrogenated bisphenol A epoxy resin, the blending amount of the hydrogenated bisphenol A epoxy resin is 30 to 98 mass% of the total solid content of the composition, the amount of the organic solvent in the composition is 30 to 70 mass % and the composition does not contain an organic solvent that dissolves dicyandiamide; the blending amount of the dicyandiamide is 1 to 5 mass% of the total solid content of the composition, a resin film having a thickness of 50 μm formed from the composition has a transmittance of 75% or less in all wavelengths of light from 400 nm to 800 nm; A 50 μm thick cured film formed from the composition has a transmittance of 85% or more for all wavelengths of light from 400 nm to 800 nm.

2. 2. The encapsulant composition according to claim 1, wherein the epoxy resin contains a liquid epoxy resin.

3. A dry film having a resin layer obtained by applying the encapsulant composition according to claim 1 or 2 onto a film and drying the applied composition.

4. A cured product obtained by curing the encapsulant composition according to claim 1 or 2, or the resin layer of the dry film according to claim 3.

5. A sealing structure comprising the cured product according to claim 4.

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