Method for manufacturing a sheet for sealing

Abstract

Provided is a method for producing a sealing sheet having a layered structure including, in order, a first moisture-proof layer, a resin composition layer, and a second moisture-proof layer, the method including: drying the resin composition layer in the absence of the second moisture-proof layer, and then, during a period from the end of the drying to the provision of the second moisture-proof layer, providing the second moisture-proof layer while maintaining the resin composition layer in a low-humidity atmosphere.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing a sealing sheet for sealing that can be used for electronic devices. BACKGROUND

[0002] In order to protect electronic devices (for example, organic EL (Electroluminescence) devices, solar cells, and the like) that are not resistant to moisture from moisture, sealing of electronic devices is performed using a sealing sheet for sealing having a resin composition layer.

[0003] On the other hand, in the case where the resin composition layer of the sealing sheet for sealing contains moisture, it is sometimes difficult to sufficiently protect the electronic devices. For example, in Patent Literature 1, a sealing sheet for sealing having a first moisture-proof film, a resin composition layer, and a second moisture-proof film is proposed in order to suppress moisture absorption of the resin composition layer at the time of storage.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: WO2018 / 181426A1. SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] If it is a sealing sheet for sealing having a stacked structure sequentially containing a first moisture-proof layer, a resin composition layer, and a second moisture-proof layer as described in Patent Literature 1, moisture absorption of the resin composition layer at the time of storage, transportation, and the like of the sealing sheet for sealing can be prevented. However, even if moisture absorption of the resin composition layer at the time of storage is prevented, in the case where the resin composition layer contains moisture at the time of manufacturing the sealing sheet for sealing, the degradation of the electronic devices can be accelerated by the moisture inside thereof. In addition, in the case of the sealing sheet for sealing having the stacked structure, even if an attempt is made to remove the moisture of the resin composition layer by a drier, since the first moisture-proof layer and the second moisture-proof layer hinder the movement of the moisture from the resin composition layer, it is difficult to effectively dry the resin composition layer.

[0009] The present application is completed in view of the above-described circumstances, and aims to manufacture a sealing sheet for sealing in which the resin composition layer is sufficiently dried and moisture absorption of the resin composition layer at the time of storage and the like is prevented.

[0010] TECHNICAL SOLUTION

[0011] The present application that can achieve the above-described object is as described below;

[0012] [1] A method for producing a sealing sheet having a layered structure including, in order, a first moisture-proof layer, a resin composition layer, and a second moisture-proof layer, wherein the method comprises: drying the resin composition layer in the absence of the second moisture-proof layer, and during a period from the end of the drying to the provision of the second moisture-proof layer, providing the second moisture-proof layer while maintaining the resin composition layer in a low-humidity atmosphere.

[0013] [2] The method according to the above [1], wherein the water vapor transmission rates of the first moisture-proof layer and the second moisture-proof layer are each independently 0 to 5 (g / m 2 / 24 hr);

[0014] [3] The method according to the above [1] or [2], wherein the moisture concentration (volume fraction) of the low-humidity atmosphere is 3300 ppm or less;

[0015] [4] The method according to any one of the above [1] to [3], wherein the resin composition layer is dried by heating;

[0016] [5] The method according to the above [4], wherein the resin composition layer is dried by heating a sheet having a layered structure including the first moisture-proof layer and the resin composition layer, with the surface of the resin composition layer on the side opposite to the side on which the first moisture-proof layer is present being exposed;

[0017] [6] The method according to the above [4] or [5], wherein the drying temperature is 80 to 220°C;

[0018] [7] The method according to any one of the above [1] to [6], wherein the resin composition layer contains semi-calcined hydrotalcite and / or calcined hydrotalcite;

[0019] [8] The method according to any one of the above [1] to [7], wherein the sealing sheet is a sheet for sealing electronic devices;

[0020] [9] The method according to the above [8], wherein the electronic device is an organic EL device or a solar cell.

[0021] Effects of the Invention

[0022] According to the present invention, a sealing sheet in which the resin composition layer is sufficiently dried and in which moisture absorption of the resin composition layer at the time of storage or the like can be prevented can be produced. DETAILED DESCRIPTION

[0023] The sealing sheet manufactured according to the present application has a layered structure sequentially comprising a first moisture-proof layer, a resin composition layer, and a second moisture-proof layer. With such a layered structure, moisture absorption of the resin composition layer at the time of storage and the like can be prevented. The first moisture-proof layer and the second moisture-proof layer can be the same or different. Furthermore, the sealing sheet can comprise layers (e.g., a release layer, an adhesive layer) different from the first moisture-proof layer, the resin composition layer, and the second moisture-proof layer between the layers, and can comprise a different layer as an outer layer.

[0024] The water vapour transmission rate (hereinafter also simply referred to as "WVTR") of the first moisture-proof layer and the second moisture-proof layer is preferably 5 (g / m 2 / 24 hr) or less, more preferably 2 (g / m 2 / 24 hr) or less, further more preferably 1.5 (g / m 2 / 24 hr) or less, still more preferably 1 (g / m 2 / 24 hr), still further more preferably 0.1 (g / m 2 / 24 hr), particularly preferably 0.05 (g / m 2 / 24 hr) or less. There is no particular limitation on the lower limit of the water vapour transmission rate of the first moisture-proof layer and the second moisture-proof layer, and the water vapour transmission rate of the first moisture-proof layer and the second moisture-proof layer is each independently, for example, 0 (g / m 2 / 24 hr) or more.

[0025] From the viewpoint of maintaining the high moisture-proof property of the sealing sheet, it is preferable that the WVTR of the first moisture-proof layer and the second moisture-proof layer be a low value. On the other hand, in the case where the sealing sheet is used to seal electronic devices and the like, one of the moisture-proof layers is removed and discarded before sealing. Therefore, from the viewpoint of cost, the moisture-proof layer that is removed before sealing can use a moisture-proof film having a relatively high WVTR and be inexpensive, and the moisture-proof property that is not removed can use a moisture-proof film having a relatively low WVTR. For example, the moisture-proof layer that is removed before sealing can use a moisture-proof film having a WVTR of 0.1 (g / m 2 / 24 hr) or more, and the moisture-proof property that is not removed can use a moisture-proof film having a WVTR of less than 0.1 (g / m 2 / 24 hr). That is, a configuration in which the WVTR of either one of the first moisture-proof layer and the second moisture-proof layer of the sealing sheet according to the present application is relatively high (e.g., 0.1 (g / m 2 / 24 hr) or more) and the WVTR of either one of the first moisture-proof layer and the second moisture-proof layer is relatively low (e.g., less than 0.1 (g / m 2 / 24 hr) can be adopted.

[0026] The water vapor permeability of the first moisture barrier layer and the second moisture barrier layer can be measured as follows. First, a test piece of 60 mmφ is punched out from the moisture barrier layer. 7.5 g of calcium chloride is weighed in an aluminum moisture permeation cup of 60 mmφ, and the test piece is installed in the moisture permeation cup. The initial mass of the moisture permeation cup with the test piece installed is measured with a precision balance. Next, after the aforementioned moisture permeation cup is left in a constant temperature test chamber at a temperature of 40°C and a humidity of 90% RH for 24 hours, the calcium chloride is weighed in, and the mass of the moisture permeation cup with the test piece installed after the moisture permeation is measured with a precision balance. The increase in mass (= mass after the moisture permeation - initial mass) is taken as the amount of water vapor permeation, and the water vapor permeability (g / m2 / 24 hr) is calculated from the amount of water vapor permeation, the permeation area, and the standing time. -3 2 (60 mmφ) is weighed in an aluminum moisture permeation cup, and the test piece is installed in the moisture permeation cup. The initial mass of the moisture permeation cup with the test piece installed is measured with a precision balance. Next, after the aforementioned moisture permeation cup is left in a constant temperature test chamber at a temperature of 40°C and a humidity of 90% RH for 24 hours, the calcium chloride is weighed in, and the mass of the moisture permeation cup with the test piece installed after the moisture permeation is measured with a precision balance. The increase in mass (= mass after the moisture permeation - initial mass) is taken as the amount of water vapor permeation, and the water vapor permeability (g / m 2 / 24 hr) is calculated from the amount of water vapor permeation, the permeation area, and the standing time. The water vapor permeability of the first moisture barrier layer and the second moisture barrier layer can be measured by separating the moisture barrier layer from the sealing film, or the water vapor permeability of the moisture barrier film used for the moisture barrier layer can be measured.

[0027] The first moisture barrier layer and the second moisture barrier layer can each have a single layer structure or a laminated structure. Preferably, the first moisture barrier layer and the second moisture barrier layer each have a laminated structure having a barrier layer and a base material. Here, the base material refers to a portion of the laminated structure other than the barrier layer. The moisture barrier layer can be formed by a moisture barrier film having a barrier layer and a base material.

[0028] The base material constituting the moisture barrier layer or the moisture barrier film can have a single layer structure or a laminated structure. As the base material constituting the moisture barrier layer, a plastic film such as a polyolefin such as polyethylene or polypropylene (PP), a polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polycarbonate (PC), polyimide (PI), a cyclic olefin polymer (COP), or polyvinyl chloride can be used. The plastic film can be used singly or in combination of two or more. Preferably, the base material is a polyethylene terephthalate film, a cyclic olefin polymer film, a polyethylene naphthalate film, or a polycarbonate film, more preferably a polyethylene terephthalate film or a cyclic olefin polymer film. The thickness of the base material (the thickness of the entire laminated film when the base material is a laminated film) is preferably 5 to 150 μm, more preferably 6 to 100 μm, and further more preferably 12 to 75 μm.

[0029] ​As the barrier layer constituting the moisture-proof layer or the moisture-proof film, for example, an inorganic film such as a metal foil (for example, an aluminum foil), a silicon dioxide vapor deposition film, a silicon nitride film, a silicon oxide film, or the like can be given. The barrier layer can be constituted of a plurality of inorganic films (for example, a metal foil and a silicon dioxide vapor deposition film). In addition, the barrier layer can be constituted of an organic substance and an inorganic substance, and can also be a composite multilayer of an organic layer and an inorganic film. The thickness of the barrier layer is preferably 0.01 to 100 μm, more preferably 0.05 to 50 μm, and further more preferably 0.05 to 30 μm.

[0030] As the moisture-proof layer, a commercially available moisture-proof film can be used. As the commercially available product, for example, "KURARISTER CI" manufactured by Kuraray Co., Ltd., "TECHBARRIER HX", "TECHBARRIER LX", and "TECHBARRIER L" manufactured by Mitsubishi Chemical Resin Corporation, "IB-PET-PXB" manufactured by Dai Nippon Printing Co., Ltd., "GL, GX series" manufactured by Hoshino Printing Co., Ltd., "AL1N30 with PET" manufactured by Toyo Aluminum Co., Ltd., "X-BARRIER" manufactured by Mitsubishi Chemical Resin Corporation, and the like can be given.

[0031] In one preferred aspect of the present application, the sealing sheet has a stacked structure in which a first moisture-proof layer, a first release layer, a resin composition layer, and a second moisture-proof layer are sequentially provided, and the first release layer is in contact with the resin composition layer. In another preferred aspect of the present application, the sealing sheet has a stacked structure in which a first moisture-proof layer, a resin composition layer, a second release layer, and a second moisture-proof layer are sequentially provided, and the resin composition layer is in contact with the second release layer. In a more preferred aspect of the present application, the sealing sheet has a stacked structure in which a first moisture-proof layer, a first release layer, a resin composition layer, a second release layer, and a second moisture-proof layer are sequentially provided, the first release layer is in contact with the resin composition layer, and the resin composition layer is in contact with the second release layer.

[0032] As the release agent forming the release layer, for example, a silicone-based release agent, an alkyd-based release agent, a fluorine-based release agent, an olefin-based release agent, or the like can be given. The release layer is preferably formed of a silicone-based release agent or an alkyd-based release agent. The thickness of the release layer is preferably 0.05 to 1 μm, more preferably 0.05 to 0.5 μm, and further more preferably 0.05 to 0.1 μm.

[0033] In the present application, the resin composition layer is not particularly limited, and a publicly known resin composition can be used to form the resin composition layer. In order to seal an organic EL device or the like well, the resin composition layer preferably contains an olefin-based resin and / or an epoxy resin. The olefin-based resin and the epoxy resin are not particularly limited, and a publicly known resin (for example, the resin described in WO2018 / 181426A1) can be used.

[0034] The amount of the olefin-based resin is not particularly limited. From the viewpoint of good coatability and the like, in the case of using an olefin-based resin, the amount thereof is preferably 80% by mass or less, more preferably 75% by mass or less, further more preferably 70% by mass or less, still more preferably 60% by mass or less, yet more preferably 55% by mass or less, particularly preferably 50% by mass or less, with respect to the entire resin composition layer (i.e., with respect to the entire nonvolatile components of the resin composition). On the other hand, from the viewpoint of improving moisture resistance and also improving transparency, the amount of the olefin-based resin is preferably 1% by mass or more, more preferably 3% by mass or more, further more preferably 5% by mass or more, still more preferably 7% by mass or more, yet more preferably 10% by mass or more, particularly preferably 20% by mass or more, most preferably 30% by mass or more, with respect to the entire resin composition layer (i.e., with respect to the entire nonvolatile components of the resin composition).

[0035] The amount of the epoxy resin is not particularly limited. In the case of using an epoxy resin, the amount thereof is preferably 10 to 80% by mass, more preferably 15 to 75% by mass, further more preferably 20 to 70% by mass, with respect to the entire resin composition layer (i.e., with respect to the entire nonvolatile components of the resin composition).

[0036] From the viewpoint of moisture barrier properties of the sealing sheet of the present application, the resin composition layer preferably contains semi-calcined hydrotalcite and / or calcined hydrotalcite, more preferably contains semi-calcined hydrotalcite. Either semi-calcined hydrotalcite or calcined hydrotalcite can be used alone, or two or more kinds thereof can be used in combination.

[0037] The sealing sheet having a resin composition layer containing uncalcined hydrotalcite and / or calcined hydrotalcite can exhibit high moisture barrier properties, and the moisture absorption of the resin composition layer increases due to the hygroscopicity of semi-calcined hydrotalcite and calcined hydrotalcite. However, according to the present application, the resin composition layer can be sufficiently dried at the time of production, and the obtained sealing sheet can prevent the moisture absorption of the resin composition layer at the time of storage or the like by the first moisture-proof layer and the second moisture-proof layer. Therefore, the present application is suitable for the production of a sealing sheet having a resin composition layer containing semi-calcined hydrotalcite and / or calcined hydrotalcite.

[0038] Hydrotalcite can be classified into uncalcined hydrotalcite, semi-calcined hydrotalcite, and calcined hydrotalcite.

[0039] Uncalcined hydrotalcite is, for example, a metal hydroxide having a layered crystal structure represented by natural hydrotalcite (Mg6Al2(OH) 16 CO3·4H2O), for example, a metal hydroxide having a layered crystal structure represented by natural hydrotalcite (Mg6Al2(OH) 1-X Al X (OH)2] X+ and an intermediate layer [(CO3) X / 2 ·mH2O] X-Formation. The uncalcined hydrotalcite in this invention is a concept of hydrotalcite-like compounds, including synthetic hydrotalcite and the like. Examples of hydrotalcite-like compounds include compounds represented by the following formulas (I) and (II).

[0040] [M 2+ 1-x M 3+ x (OH)2] x+ ·[(A n- ) x / n ·mH2O] x- (I)

[0041] (where M is in the formula) 2+ Indicates Mg 2+ Zn 2+ divalent metal ions, M 3+ Indicates Al 3+ Fe 3+ Trivalent metal ions, A n- CO3 2- Cl - NO3 - (For anions with the same n-valent valence, 0 < x < 1, 0 ≤ m < 1, and n is a positive number.)

[0042] In formula (I), M 2+ Mg is better 2+ M 3+ Al is better 3+ A n- CO3 is better 2- .

[0043] M 2+ x Al2(OH) 2x+6-nz (A n- ) z ·mH2O (II)

[0044] (where M is in the formula) 2+ Indicates Mg 2+ Zn 2+ Isovalent metal ions, A n- CO3 2- Cl - NO3 - For anions with the same n-valent oxidation state, x is a positive number greater than 2, z is a positive number less than 2, m is a positive number, and n is a positive number.

[0045] In equation (II), M 2+ Mg is better 2+ A n- CO3 is better 2- .

[0046] The semi-calcined hydrotalcite refers to a metal hydroxide having a layered crystal structure in which the amount of interlayer water is reduced or disappears, which is obtained by calcining the uncalcined hydrotalcite. If explained using the composition formula, the "interlayer water" refers to "H2O" described in the composition formula of the above uncalcined natural hydrotalcite and the hydrotalcite-like compound.

[0047] On the other hand, the calcined hydrotalcite refers to a metal oxide having an amorphous structure in which not only the interlayer water disappears but also the hydroxyl group disappears due to condensation dehydration, which is obtained by calcining the uncalcined hydrotalcite or the semi-calcined hydrotalcite.

[0048] The uncalcined hydrotalcite, the semi-calcined hydrotalcite, and the calcined hydrotalcite can be distinguished by the saturated water absorption rate. The saturated water absorption rate of the semi-calcined hydrotalcite is 1 mass% or more and less than 20 mass%. On the other hand, the saturated water absorption rate of the uncalcined hydrotalcite is less than 1 mass%, and the saturated water absorption rate of the calcined hydrotalcite is 20 mass% or more.

[0049] The "saturated water absorption rate" in the present application refers to that 1.5 g of the uncalcined hydrotalcite, the semi-calcined hydrotalcite, or the calcined hydrotalcite is weighed using a balance, the initial mass is measured, and then, after being left in a small environmental tester (manufactured by ESPEC Corporation, SH-222) set to 60°C and 90% RH (relative humidity) under atmospheric pressure for 200 hours, the mass increase rate with respect to the initial mass after the 200 hours of leaving is calculated using the following formula (i):

[0050] Saturated water absorption rate (mass%) = 100 x (mass after moisture absorption - initial mass) / initial mass (i).

[0051] The saturated water absorption rate of the semi-calcined hydrotalcite is preferably 3 mass% or more and less than 20 mass%, and more preferably 5 mass% or more and less than 20 mass%.

[0052] In addition, the uncalcined hydrotalcite, the semi-calcined hydrotalcite, and the calcined hydrotalcite can be distinguished by the thermogravimetric reduction rate determined by thermogravimetric analysis. The thermogravimetric reduction rate of the semi-calcined hydrotalcite at 280°C is less than 15 mass%, and the thermogravimetric reduction rate thereof at 380°C is 12 mass% or more. On the other hand, the thermogravimetric reduction rate of the uncalcined hydrotalcite at 280°C is 15 mass% or more, and the thermogravimetric reduction rate of the calcined hydrotalcite at 380°C is less than 12 mass%.

[0053] For the thermogravimetric analysis, TG / DTA EXSTAR 6300 manufactured by Hitachi High-Tech Science Corporation was used, 5 mg of the hydrotalcite was weighed into an aluminum sample pan, and the measurement was performed from 30°C to 550°C at a temperature increase rate of 10°C / minute in an atmosphere in which the nitrogen flow rate was 200 mL / minute in an open state without a cap. The thermogravimetric reduction rate can be calculated using the following formula (ii):

[0054] Thermal weight reduction rate (%) = 100 x (mass before heating - mass at prescribed temperature) / mass before heating (ii).

[0055] Further, the uncalcined hydrotalcite, the semi-calcined hydrotalcite and the calcined hydrotalcite can be distinguished based on the peaks and the relative intensity ratio determined by powder X-ray diffraction. For the semi-calcined hydrotalcite, using powder X-ray diffraction, a peak split into two is shown in the vicinity of 8 to 18° in 2θ, or a peak having a shoulder peak is shown by the synthesis of the two peaks, the relative intensity ratio of the diffraction intensity of the peak or shoulder peak appearing on the low angle side (= low angle side diffraction intensity) to the diffraction intensity of the peak or shoulder peak appearing on the high angle side (= high angle side diffraction intensity) (low angle side diffraction intensity / high angle side diffraction intensity) is 0.001 to 1,000. On the other hand, the uncalcined hydrotalcite has only one peak in the vicinity of 8 to 18°, or the relative intensity ratio of the diffraction intensity of the peak or shoulder peak appearing on the low angle side to the diffraction intensity of the peak or shoulder peak appearing on the high angle side falls outside the aforementioned range. The calcined hydrotalcite has no characteristic peak in the region of 8 to 18°, and has a characteristic peak at 43°. For the powder X-ray diffraction measurement, using a powder X-ray diffraction device (PANalytical, Empyrean), measurement was performed under the conditions of CuKα voltage of 45 V, a current of 40 mA, a sampling width of 0.0260°, a scanning speed of 0.0657° / s, and a measurement diffraction angle range (2θ) of 5.0131 to 79.9711°. The peak search can be performed using the peak search function of the software attached to the diffraction device under the conditions of "minimum significance of 0.50, minimum peak tip of 0.01°, maximum peak tip of 1.00°, peak baseline width of 2.00°, and method of minimum value of second-order differential".

[0056] The BET specific surface area of the semi-calcined hydrotalcite and the calcined hydrotalcite is preferably 1 to 250 m 2 / g, more preferably 5 to 200 m 2 / g. The BET specific surface area thereof can be calculated using the BET multipoint method by adsorbing nitrogen gas to the surface of the sample using a specific surface area measuring device (Macsorb HM 1210, manufactured by MOUNTECH Corporation) according to the BET method.

[0057] The particle diameter of the semi-calcined hydrotalcite and the calcined hydrotalcite is preferably 1 to 1000 nm, more preferably 10 to 800 nm. The average particle diameter thereof is the median particle diameter of the particle size distribution when the particle size distribution is made on a volume basis.

[0058] The semi-calcined hydrotalcite and the semi-calcined hydrotalcite can each be a substance subjected to surface treatment with a surface treatment agent. The surface treatment agent used for the surface treatment is not particularly limited, and a publicly known surface treatment agent (for example, the surface treatment agent described in WO2018 / 181426A1) can be used.

[0059] The amount of the semi-calcined hydrotalcite is not particularly limited. From the viewpoint of the moisture barrier property of the sealing sheet, the amount of the semi-calcined hydrotalcite is preferably 3 to 80% by mass, more preferably 5 to 75% by mass, and further more preferably 10 to 70% by mass, relative to the entire resin composition layer (i.e., relative to the entire nonvolatile components of the resin composition).

[0060] As the semi-calcined hydrotalcite, for example, "DHT-4C" (manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter: 400 nm), "DHT-4A-2" (manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter: 400 nm), and the like can be given. On the other hand, as the calcined hydrotalcite, for example, "KW-2200" (manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter: 400 nm), and the like can be given, and as the uncalcined hydrotalcite, for example, "DHT-4A" (manufactured by Kyowa Chemical Industry Co., Ltd., particle diameter: 400 nm), and the like can be given.

[0061] The resin composition layer can contain other components different from the above-described olefin-based resin, epoxy resin, and semi-calcined hydrotalcite. The other components are not particularly limited, and a publicly known component (for example, the component described in WO2018 / 181426A1) as a component of a resin composition for sealing can be used.

[0062] The thickness of the resin composition layer is preferably 3 to 75 μm, more preferably 3 to 50 μm, and further more preferably 5 to 50 μm.

[0063] The sealing sheet having the layered structure including the first moisture-proof layer, the resin composition layer, and the second moisture-proof layer in this order can be manufactured, for example, by applying a resin composition varnish to the first moisture-proof layer and drying to form the resin composition layer, and then bonding the second moisture-proof layer to the obtained resin composition layer. For bonding the second moisture-proof layer, an adhesive can be used.

[0064] The sealing sheet having a stacked structure sequentially comprising a first moisture-proof layer, a first release layer, a resin composition layer, a second release layer, and a second moisture-proof layer, the first release layer being in contact with the resin composition layer, and the resin composition layer being in contact with the second release layer, for example, can be manufactured by applying a resin composition varnish to the first release layer of a laminate having such a structure of a first release layer / first moisture-proof layer, and drying, to form a resin composition layer, and laminating a laminate having such a structure of a second release layer / second moisture-proof layer on the obtained resin composition layer, in such a manner that the resin composition layer is in contact with the second release layer. The sealing sheet having a stacked structure sequentially comprising a first moisture-proof layer, a first release layer, a resin composition layer, and a second moisture-proof layer, the first release layer being in contact with the resin composition layer, and the sealing sheet having a stacked structure sequentially comprising a first moisture-proof layer, a resin composition layer, a second release layer, and a second moisture-proof layer, the resin composition layer being in contact with the second release layer, can also be manufactured in the same manner.

[0065] As the laminate having such a structure of a release layer / moisture-proof layer, a commercially available product (for example, a moisture-proof film with a release layer) can be used. In addition, a release agent can be applied to a moisture-proof layer and dried, to manufacture a laminate having such a structure of a release layer / moisture-proof layer.

[0066] The resin composition varnish can be manufactured by mixing the components of the resin composition and an organic solvent using a kneader roll or a rotary mixer, or the like. The nonvolatile component of the resin composition varnish is preferably 20 to 80% by mass, and more preferably 30 to 70% by mass.

[0067] As the organic solvent, for example, ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, and the like; acetates such as ethyl acetate, butyl acetate, cellulose solvent acetate, propylene glycol monomethyl ether acetate, carbitol acetate, and the like; carbitols such as cellulose solvent, butyl carbitol, and the like; aromatic hydrocarbons such as toluene, xylene, and the like; dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like; and aromatic mixed solvents such as solvent naphtha, and the like can be mentioned. In addition, as a commercial product of the aromatic mixed solvent, for example, "Swasol" (manufactured by Maruzen Petrochemical Co., Ltd.), "Ipzole" (manufactured by Idemitsu Kosan Co., Ltd.) can be mentioned. The organic solvent can be used alone or in combination of two or more kinds.

[0068] The present application is characterized in that the resin composition layer is dried in the absence of the second moisture-proof layer, and the second moisture-proof layer is provided while the resin composition layer is maintained in a low-humidity atmosphere during the period from the end of the drying to the provision of the second moisture-proof layer. By this feature, the moisture absorption of the resin composition layer at the time of the manufacture can be prevented, and a sealing sheet comprising a resin composition layer that is sufficiently dried can be manufactured.

[0069] The drying of the resin composition layer can be carried out simultaneously with the formation of the resin composition layer based on the drying of the resin composition varnish. That is, the formation and drying of the resin composition layer based on the drying of the resin composition varnish can be carried out in one step, and the second moisture-proof layer is applied while the resin composition layer is kept in a low humidity atmosphere from the end of drying until the second moisture-proof layer is applied.

[0070] The drying of the resin composition layer can be performed separately from the formation of the resin composition layer based on the drying of the resin composition varnish. That is, in addition to the step of forming the resin composition layer by drying the resin composition varnish, the step of drying the formed resin composition layer can be performed separately, and the second moisture-proof layer is applied while the resin composition layer is kept in a low-humidity atmosphere from the end of drying until the second moisture-proof layer is applied. It should be noted that when the steps of forming the resin composition layer and drying the resin composition layer are not performed continuously, in order to prevent the adhesion of debris to the resin composition layer, a covering film can be applied to the resin composition layer first, and the covering film can be peeled off before the drying step, or if the covering film has sufficient moisture permeability (equivalent to the moisture permeability layer disclosed later), the drying can be performed directly.

[0071] The morphology of the dried resin composition layer in the absence of a second moisture-proof layer includes:

[0072] (1) The morphology of the resin composition layer is dried with at least one surface of the resin composition layer exposed, and

[0073] (2) The resin composition layer is dried while at least one surface of the resin composition layer is covered by a moisture-permeable layer. From the viewpoint of drying efficiency, the state described in (1) is preferred, but from the viewpoint of inhibiting the adhesion of debris and the like to the resin composition layer, the state described in (2) is preferred. The exposed surface of the resin composition layer or the surface opposite to the surface covered by the moisture-permeable layer may be exposed, or it may be covered by other layers (e.g., a first moisture-proof layer).

[0074] Examples of membranes and sheets used as moisture permeable layers include porous polyolefin membranes and low-crystallinity polyolefin membranes. As long as a certain level of moisture permeability is achieved, the aforementioned plastic membranes can be used, as well as commercially available membranes and sheets such as breathable membranes and moisture-permeable sheets. A preferred water vapor permeability for the moisture permeable layer is 10 g / m³. 2 (24hr) or more, preferably 30 (g / m 2 ( / 24hr) or higher, and even better, 50 (g / m³) 2 ( / 24hr) or higher, especially 100 (g / m³) 2 ( / 24hr) or more, preferably 150 (g / m2 The upper limit is not particularly limited, and is, for example, 20,000 (g / m 2 The thickness of the moisture permeable layer is preferably 1 to 200 μm, more preferably 1 to 75 μm, and even more preferably 1 to 25 μm.

[0075] The drying of the resin composition layer can be performed by any one of heating drying, vacuum drying, or a combination thereof. In addition, the drying of the resin composition layer can be performed in an atmospheric atmosphere or in an inert gas atmosphere.

[0076] In the present application, the resin composition layer is preferably dried by heating, and more preferably dried by heating a sheet having a layered structure including the first moisture-proof layer and the resin composition layer, and the surface of the resin composition layer on the side opposite to the side on which the first moisture-proof layer is present is exposed. The drying conditions such as the drying temperature, the drying time, and the vacuum degree are different depending on the moisture content of the resin composition layer, the desired moisture content, the type of the drying machine, and the like.

[0077] The drying temperature is appropriately set within a range of 80 to 220°C. In the case of a thermosetting resin composition, the temperature is preferably 80 to 150°C. In the case of a thermoplastic resin or a pressure-sensitive adhesive resin composition, the temperature is preferably 100 to 180°C. The drying time is preferably 1 to 180 minutes, more preferably 3 to 150 minutes, and even more preferably 5 to 120 minutes. In this regard, the drying temperature means the temperature in the drying machine in the case of drying by a drying machine, and means the temperature of the heating portion of the heating machine (e.g., a hot plate) in the case of heating drying by a heating machine.

[0078] The drying of the resin composition layer can be performed separately from the formation of the resin composition layer based on the drying of the resin composition varnish, or simultaneously with the formation of the resin composition layer based on the drying of the resin composition varnish. The drying temperature and the drying time are the same as the above-described ranges.

[0079] The vacuum degree in the case of vacuum drying is not particularly limited as long as it is a pressure lower than the atmospheric pressure, and is preferably 10 to 100,000 Pa, more preferably 10 to 10,000 Pa, and even more preferably 10 to 1,000 Pa.

[0080] The moisture concentration (mass fraction) of the resin composition layer after drying is preferably lower (ideally 0 ppm), and is more preferably 1,500 ppm or less, even more preferably 1,000 ppm or less, even more preferably 500 ppm or less, even more preferably 200 ppm or less, and even more preferably 100 ppm or less.

[0081] The drying of the resin composition layer can be performed by a publicly known drying machine. The drying machine can be a batch-type drying machine or a continuous-type drying machine. The drying machine can be one in which a high-temperature object is brought into contact with the drying target, or one in which light is irradiated onto the drying target. As the former, for example, a hot-air circulating oven, a heated conveyance roller, and the like can be given. As the latter, for example, a near-infrared ray irradiation oven and the like can be given. Further, the drying can also be performed by placing a heating machine (e.g., a hot plate) in a container (e.g., a glove box) in which the inside atmosphere can be maintained as a low-humidity atmosphere, and heating the resin composition varnish or the resin composition layer with the heating machine.

[0082] After the second moisture-proof layer is provided, drying of the resin composition layer becomes substantially difficult, or the drying efficiency is significantly reduced, and thus the drying end time in the present application means the time when the drying operation is ended or when the second moisture-proof layer is provided. Further, in the case where the drying is performed by a continuous-type drying machine, the time when the drying operation is ended means the time when the drying target is sent out of the continuous-type drying machine. Further, in the case where the drying is performed by a heating machine such as a hot plate, the time when the drying operation is ended means the time when the heating is ended.

[0083] The period from the time when the drying is ended to the time when the second moisture-proof layer is provided is a period in which the resin composition layer is maintained in a state under a low-humidity atmosphere. The period from the time when the drying is ended to the time when the second moisture-proof layer is provided includes both a state in which the resin composition layer is maintained under a low-humidity atmosphere during the period and a state in which the resin composition layer is not maintained under a low-humidity atmosphere during the period.

[0084] The period from the time when the drying is ended to the time when the second moisture-proof layer is provided is a period in which the resin composition layer is maintained under a low-humidity atmosphere. The period from the time when the drying is ended to the time when the second moisture-proof layer is provided includes both a state in which the resin composition layer is maintained under a low-humidity atmosphere during the period and a state in which the resin composition layer is not maintained under a low-humidity atmosphere during the period.

[0085] (i) a state in which the resin composition layer is maintained under a low-humidity atmosphere after the drying operation is ended, and the second moisture-proof layer is provided while the resin composition layer is maintained under a low-humidity atmosphere; and

[0086] (ii) a state in which the resin composition layer is maintained under a low-humidity atmosphere after the drying operation is not ended, and the second moisture-proof layer is provided while the drying under a low-humidity atmosphere is continued.

[0087] Note that in the state of (ii) described above, the "time when the drying is ended" is the same as the "time when the second moisture-proof layer is provided". Therefore, in the state of (ii) described above, the "period from the time when the drying is ended to the time when the second moisture-proof layer is provided" = "the time when the drying is ended" = "the time when the second moisture-proof layer is provided".

[0088] As a mode of providing the second moisture-proof layer while keeping the resin composition layer in a low-humidity atmosphere, for example, the following modes can be given:

[0089] (a) a mode of adhering a film containing the second moisture-proof layer or the second moisture-proof layer to the exposed surface of the resin composition layer while keeping the resin composition layer in a low-humidity atmosphere;

[0090] (b) a mode of adhering a film containing the second moisture-proof layer or the second moisture-proof layer to the moisture-permeable layer on the resin composition layer while keeping the resin composition layer in a low-humidity atmosphere;

[0091] (c) a mode of forming a precursor layer capable of forming the second moisture-proof layer on the exposed surface of the resin composition layer by coating or the like while keeping the resin composition layer in a low-humidity atmosphere, and forming the second moisture-proof layer by applying a treatment such as heating;

[0092] (d) a mode of forming a precursor layer capable of forming the second moisture-proof layer on the moisture-permeable layer on the resin composition layer by coating or the like while keeping the resin composition layer in a low-humidity atmosphere, and forming the second moisture-proof layer by applying a treatment such as heating;

[0093] (e) a mode of forming the second moisture-proof layer by vapor depositing an inorganic substance forming a barrier layer on the exposed surface of the resin composition layer while keeping the resin composition layer in a low-humidity atmosphere;

[0094] (f) a mode of forming the second moisture-proof layer by vapor depositing an inorganic substance forming a barrier layer on the moisture-permeable layer on the resin composition layer while keeping the resin composition layer in a low-humidity atmosphere.

[0095] Among them, from the viewpoint of the ease of operation, the mode of (a) above is preferable.

[0096] The modes of (a) to (d) above can be implemented, for example, by keeping the atmosphere in a drying machine or the container (e.g., a glove box) described above in a low-humidity atmosphere while performing the adhesion of the second moisture-proof layer or the coating and drying of the moisture-proof resin composition.

[0097] The modes of (e) and (f) above can be performed, for example, in an apparatus in which a drying machine, a connecting space having a conveyance mechanism, and a vapor deposition device are connected in this order and all the spaces are maintained under reduced pressure (preferably, for example, 10 -7 (Torr) or less), the resin composition is dried by the drying machine, the resin composition is transferred to the vapor deposition device by the conveyance mechanism, and the barrier layer is formed by the vapor deposition device.

[0098] From the viewpoint of drying, the lower the moisture concentration (volume fraction) of the low-humidity atmosphere is, the better (ideally 0 ppm), preferably 3300 ppm or less, more preferably 2000 ppm or less, further more preferably 1000 ppm or less, further more preferably 500 ppm or less, further more preferably 200 ppm or less, further more preferably 100 ppm or less, further more preferably 50 ppm or less, further more preferably 10 ppm or less, further more preferably 5 ppm or less, further more preferably 1 ppm or less, further more preferably 0.5 ppm or less, further more preferably 0.1 ppm or less.

[0099] In the present application, it is particularly preferable that, after the resin composition layer is dried by heating the sheet having a layered structure including the first moisture-proof layer and the resin composition layer, and the surface of the resin composition layer on the side opposite to the side on which the first moisture-proof layer is present is exposed, from the time when the drying is completed until the film including the second moisture-proof layer or the second moisture-proof layer is attached, the resin composition layer is kept in a low-humidity atmosphere while the film including the second moisture-proof layer or the second moisture-proof layer is attached to the exposed surface of the resin composition layer.

[0100] According to the present application, a sealing sheet in which a resin composition layer is sufficiently dried and in which moisture absorption of the resin composition layer at the time of storage or the like is prevented can be produced. Therefore, the sealing sheet obtained by the present application can be used for sealing of electronic devices (for example, organic EL devices, solar cells, and the like).

[0101] Examples

[0102] Hereinafter, the present application will be described more specifically by citing examples, but the present application is not limited by the following examples, and of course, the present application can be implemented by appropriately making changes within a range in which the gist of the context can be maintained, and these are included in the technical scope of the present application.

[0103] Film

[0104] The films used in the examples and comparative examples are described below.

[0105] PET film with release layer: "E7004" manufactured by Toyo Spinning Co., Ltd. (polyethylene terephthalate (PET) film with release layer, release layer: silicone release layer, thickness of substrate (PET film): 38 μm, water vapor permeability: 34 g / m 2 / 24 hr) moisture-proof film 1: "TECH BARRIER HX" manufactured by Mitsubishi Chemical Corporation (PET film with barrier layer, barrier layer: silicon oxide vapor deposition film, thickness of substrate (PET film): 12.5 μm, water vapor permeability: 0.5 g / m 2 / 24 hr)

[0106] Moisture-proof film 2: "VERREAL UD" (PET film with barrier layer, barrier layer: silica vapor deposition film, thickness of base material (PET film): 50 μm, water vapor permeability: 0.01 g / m 2 / 24 hr).

[0107] Production Example 1: Production of a moisture-proof film with a release layer

[0108] The surface of the PET film on the opposite side of the release layer of the PET film with release layer was adhered to the surface of the base material (PET film) on the opposite side of the barrier layer of the moisture-proof film 1 with an adhesive to produce a moisture-proof film with release layer having a layered structure of PET film with release layer (release layer / PET film) / adhesive layer / moisture-proof film 1 (PET film / barrier layer) (total thickness of the moisture-proof film with release layer: 55 μm). Note that in the moisture-proof film with release layer, the moisture-proof film 1 corresponds to the moisture-proof layer.

[0109] Production Example 2: Production of a resin composition varnish

[0110] To 130 parts by mass of a saturated hydrocarbon resin containing a cyclohexane ring ("ARKON P125" manufactured by Arakawa Chemical Industries, Ltd., 60% by mass in Swasol) was added 35 parts by mass of a maleic anhydride-modified liquid polyisobutylene ("HV-300M" manufactured by DKS Co., Ltd.), 60 parts by mass of a polybutene ("HV-1900" manufactured by JXTG Energy), and 100 parts by mass of a semi-calcined hydrotalcite ("DHT-4C" manufactured by Kyowa Chemical Industry Co., Ltd.) using a three-roll mill to obtain a mixture. To the obtained mixture were added 200 parts by mass of a 20% by mass Swasol solution of a glycidyl methacrylate-modified polypropylene-polybutene copolymer ("T-YP341" manufactured by Seiko PMC Co., Ltd.), 0.5 parts by mass of a curing accelerator (2,4,6-tris(dimethylaminomethyl)phenol), and 16 parts by mass of toluene, and the obtained mixture was uniformly dispersed using a high-speed rotary mixer to obtain an olefin-based resin composition varnish.

[0111] Production Example 3: Production of a sealing sheet without drying

[0112] The resin composition varnish obtained in Production Example 2 was uniformly applied to the surface of the release layer of the moisture-proof film with release layer obtained in Production Example 1 using a kiss coater, and heated at 130°C for 60 minutes to obtain a sealing sheet having a resin composition layer with a thickness of 20 μm (amount of residual solvent in the resin composition layer: about 1 mass%). Next, while the sealing sheet was wound in a roll with the resin composition layer of the sealing sheet in contact with the surface of the release layer of the moisture-proof film with release layer obtained in Production Example 1, the sealing sheet was cut into 40 mm x 80 mm to produce a sealing sheet that had not been dried. The sealing sheet that had not been dried had a temporary moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) stacked structure.

[0113] Production Example 4: Production of a moisture-proof film with an adhesive layer

[0114] A polyolefin-based adhesive film (thickness 10 μm) was adhered to the surface of the barrier layer of the moisture-proof film 2 to produce a moisture-proof film with adhesive layer having a stacked structure of the moisture-proof film 2 (base material / barrier layer) / adhesive layer.

[0115] Example 1

[0116] A hot plate (150°C) was prepared in a nitrogen glove box in which the moisture concentration (volume fraction) was less than 0.1 ppm (detection limit of the apparatus 0.1 ppm). A sheet obtained by removing the moisture-proof film with release layer from the sealing sheet that had not been dried obtained in Production Example 3 (i.e., a film having a stacked structure of a temporary moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer) (i.e., a sheet having a stacked structure of a resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1)) was heated on the hot plate with the resin composition layer facing upward for 30 minutes to dry the resin composition layer (hereinafter, the obtained sheet will be referred to simply as "dried unfinished sheet"). After 10 minutes from the time when the heating was stopped, the moisture-proof film with release layer obtained in Production Example 1 (i.e., a film having a stacked structure of a second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer) was attached to the resin composition layer of the dried unfinished sheet by pressing with a rubber roll heated to 60°C at a pressure of 0.3 MPa or more directly in the glove box to produce a sealing sheet. The obtained sealing sheet had a stacked structure of a second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1).

[0117] Example 2

[0118] The sheet obtained by removing the release layer-equipped moisture-proof film (i.e., the film having the temporary moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer such a stacked structure) from the non-dried sealing sheet obtained in Production Example 3 (i.e., the sheet having the resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) such a stacked structure) was dried in a hot air drying oven at a temperature of 150°C with the resin composition layer facing upward. Subsequently, the release layer-equipped moisture-proof film obtained in Production Example 1 (i.e., the film having the second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer such a stacked structure) and the dried sheet having the resin composition layer were conveyed to a roll laminator in a chamber at 1013 hPa and 25°C at a relative humidity of 6%RH (moisture concentration (volume fraction): 1800 ppm) and the temperature was adjusted to 30°C, and the release layer-equipped moisture-proof film obtained in Production Example 1 was attached to the resin composition layer by pressing with a rubber roll heated to 60°C at a pressure of 0.3 MPa or more to produce a sealing sheet. The obtained sealing sheet had a stacked structure of the second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1).

[0119] Example 3

[0120] A hot plate at 150°C was prepared in a nitrogen glove box in which the moisture concentration (volume fraction) was made lower than 0.1 ppm (0.1 ppm, the detection limit of the apparatus). After the release layer-equipped moisture-proof film was removed from the non-dried sealing sheet obtained in Production Example 3 (i.e., the film having the temporary moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer such a stacked structure), the release layer-equipped PET film (water vapor permeability: 34 g / m 2 / 24 hr, used as a moisture permeable layer), a resin composition layer, and a moisture-proof film with a release layer in this order. More specifically, the resulting sheet had a PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) such a stacked structure. The resin composition layer was dried by heating the sheet with the PET film with a release layer (i.e., a film having a stacked structure of a PET film / release layer) facing upward for 30 minutes. After 10 minutes from the stop of heating, the adhesive layer side of the moisture-proof film with an adhesive layer obtained in Production Example 4 (i.e., a film having a stacked structure of a second moisture-proof layer (moisture-proof film 2) / adhesive layer) was attached to the PET film with a release layer of the sheet having a stacked structure of a PET film with a release layer, a dried resin composition layer, and a moisture-proof film with a release layer in this order by pressing with a rubber roll warmed to 60°C at a pressure of 0.3 MPa or more in a glove box. A sheet for sealing having a stacked structure of a moisture-proof film with an adhesive layer, a PET film with a release layer, a resin composition layer, and a moisture-proof film with a release layer in this order was produced. More specifically, the resulting sheet for sealing had a second moisture-proof layer (moisture-proof film 2) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) such a stacked structure.

[0121] Comparative Example 1

[0122] A sheet for sealing was produced by placing the dried unfinished sheet obtained in the same manner as in Example 1 in an atmosphere of 25°C and 40% RH (moisture concentration (volume fraction): 12500 ppm) for 10 minutes with the resin composition exposed, and then attaching the moisture-proof film with a release layer obtained in Production Example 1 to the resin composition layer of the sheet by pressing with a rubber roll warmed to 60°C at a pressure of 0.3 MPa or more. The resulting sheet for sealing had a second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) such a stacked structure.

[0123] Comparative Example 2

[0124] A sheet for sealing was produced by placing the dried unfinished sheet obtained in the same manner as in Example 1 in an atmosphere of 25°C and 40% RH (moisture concentration (volume fraction): 12500 ppm) for 10 minutes with the resin composition exposed, and then attaching the moisture-proof film with a release layer obtained in Production Example 1 to the resin composition layer of the sheet by pressing with a rubber roll warmed to 60°C at a pressure of 0.3 MPa or more. The resulting sheet for sealing had a second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1) such a stacked structure.

[0125] Comparative Example 3

[0126] A sealing sheet was produced by removing the "temporary moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer" portion from the non-dried sealing sheet obtained in Production Example 3, using the temporary moisture-proof layer as the second moisture-proof layer, and drying under the same drying conditions as in Example 1 (heating and drying for 30 minutes in a nitrogen glove box (moisture concentration (volume fraction): less than 0.1 ppm) using a hot plate (150°C) with the first moisture-proof layer on the side of the hot plate). The resulting sealing sheet had a layered structure of second moisture-proof layer (moisture-proof film 1) / adhesive layer / PET film / release layer / resin composition layer / release layer / PET film / adhesive layer / first moisture-proof layer (moisture-proof film 1).

[0127] < Evaluation of Resin Composition Layer of Sealing Sheet >

[0128] The moisture concentration (mass fraction) of the resin composition layer of the sealing sheets obtained in Examples 1 and 2 and Comparative Examples 1 to 3 immediately after production (hereinafter referred to as "moisture concentration (mass fraction) immediately after production") and the moisture concentration (mass fraction) of the resin composition layer after standing for 24 hours in an atmosphere of 25°C and 40% RH (hereinafter referred to as "moisture concentration (mass fraction) after standing") were calculated by the following method. The results are shown in Table 1.

[0129] The resin composition layer was removed from the sealing sheet in a nitrogen glove box in which the moisture concentration (volume fraction) was less than 0.1 ppm (detection limit of the apparatus 0.1 ppm). The resin composition layer was folded to an appropriate size to prepare a sample, and the weight was measured. Next, the sample was put into a gasification cylinder of a Karl Fischer's moisture measuring apparatus (Karl Fischer's Moisture Measuring Apparatus CA-200, manufactured by Mitsubishi Chemical Analytech Corporation) while preventing contact with a moisture-containing space, and heated to 130°C. The moisture concentration (mass fraction) (ppm) of the sample (i.e., the resin composition layer) was calculated from the total gasification moisture amount from the start of heating until the moisture detection amount per second was less than 0.15 μg / sec and the weight of the sample. The moisture concentration (mass fraction) of 500 ppm or less was evaluated as O, and the moisture concentration (mass fraction) exceeding 500 ppm was evaluated as X.

[0130] [Table 1]

[0131]

[0132] *1 In Comparative Example 2, the moisture concentration (volume fraction) in the atmosphere at the time of attaching the non-moisture-proof layer (PET film) was measured.

[0133] *2In Comparative Example 3, the temporary moisture-proof layer was not removed and used as the second moisture-proof layer, and the resin composition layer was dried in a state with the temporary moisture-proof layer.

[0134] For the sealing sheet obtained in Examples 1 to 3, both the moisture concentration (mass fraction) immediately after production and the moisture concentration (mass fraction) after standing were sufficiently low. On the other hand, in Comparative Example 1 in which the film including the second moisture-proof layer was attached in an atmosphere with a high moisture concentration, the moisture concentration (mass fraction) immediately after production was high. Further, in Comparative Example 2 in which a non-moisture-proof layer was used instead of the second moisture-proof layer, the moisture concentration (mass fraction) after standing was high. Further, in Comparative Example 3 in which the resin composition layer was dried in a state with the temporary moisture-proof layer, the moisture concentration (mass fraction) immediately after production was high.

[0135] It should be noted that in Comparative Example 1 in which the second moisture-proof layer was formed, it is considered that the moisture adhered to the moisture-proof film with the release layer moved to the resin composition layer, and thus the moisture concentration of the resin composition layer after standing increased.

[0136] Further, it is considered that the reason why the moisture concentration immediately after production was high in Comparative Example 3 is that, at the time of drying, the moisture moved from the resin composition layer to the moisture-proof film with the release layer (i.e., the film having a stacked structure of the second moisture-proof layer (moisture-proof film 1) / the adhesive layer / the PET film / the release layer), and in the standing, the moisture moved again to the resin composition layer.

[0137] Possibility of use in industry

[0138] The sealing sheet obtained by the present application can be used for sealing of electronic devices (for example, organic EL devices, sensor devices, solar cells, and the like).

[0139] This application is based on Japanese Patent Application No. 2019-180593 filed in Japan, the contents of which are incorporated herein in its entirety.

Claims

1. A method for manufacturing a sealing sheet, the sealing sheet having a laminated structure comprising a first moisture-proof layer, a resin composition layer, and a second moisture-proof layer in sequence. in, The method includes: drying the formed resin composition layer in the absence of a second moisture-proof layer, and, from the end of drying until the application of the second moisture-proof layer, maintaining the resin composition layer in a low-humidity atmosphere while applying the second moisture-proof layer. The moisture concentration of the dried resin composition layer is below 200 ppm by mass fraction. The moisture concentration in the low humidity atmosphere is below 3300 ppm by volume.

2. The method according to claim 1, wherein, The water vapor transmission rates of the first and second moisture-proof layers are each independently 0–5 g / m². 2 / 24hr.

3. The method according to claim 2, wherein, The water vapor transmission rates of the first and second moisture-proof layers are independently 0–2 g / m². 2 / 24hr.

4. The method according to claim 1, wherein, The moisture concentration in the low humidity atmosphere is below 200 ppm by volume.

5. The method according to claim 1, wherein, The resin composition layer is dried by heating.

6. The method according to claim 5, wherein, A resin composition layer is dried by heating a sheet having a laminated structure comprising a first moisture-proof layer and a resin composition layer, with the surface of the resin composition layer on the side opposite to the side containing the first moisture-proof layer exposed.

7. The method according to claim 5 or 6, wherein, The drying temperature is 80–220℃.

8. The method according to claim 1 or 2, wherein, The resin composition layer contains semi-calcined hydrotalcite and / or calcined hydrotalcite.

9. The method according to claim 8, wherein, The resin composition layer contains semi-calcined hydrotalcite.

10. The method according to claim 9, wherein, The content of semi-calcined hydrotalcite is 3-80% by mass relative to the overall resin composition layer.

11. The method according to claim 10, wherein, The content of semi-calcined hydrotalcite is 5-75% by mass relative to the overall resin composition layer.

12. The method according to claim 1 or 2, wherein, Sealing sheets are sheets used to seal electronic devices.

13. The method according to claim 12, wherein, The electronic devices are organic EL devices or solar cells.

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