Method for manufacturing sealing sheets

Abstract

To provide a sheet for encapsulation with a polymer composition layer of which has a sufficiently reduced moisture content, enabling omission of pre-drying.SOLUTION: A sheet for encapsulation has a laminated structure, comprising a support medium, a polymer composition layer, and a protective sheet in this order, where the polymer composition layer comprises an olefinic polymer having a crosslinked structure and calcium oxide, a content of the calcium oxide is 40 mass% or more relative to 100 mass% of a nonvolatile content of the polymer composition layer, and a moisture content of the polymer composition layer is 500 ppm or less based on a mass relative to the whole polymer composition layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to sealing sheets and polymer composition layers useful for sealing electronic devices. [Background technology]

[0002] Protecting electronic devices such as OLED (Electroluminescence) devices and solar cells from moisture. To protect them, electronic devices are sometimes encapsulated using polymer composition layers.

[0003] Polymer composition layers suitable for encapsulating electronic devices are known to contain hygroscopic fillers. For example, Patent Document 1 discloses an encapsulation sheet comprising a support and a polymer composition layer containing a hygroscopic metal hydroxide.

[0004] In sealing sheets (especially sealing sheets using hygroscopic fillers), the sealing sheet is dried before sealing in order to prevent moisture present on the surface and inside of the polymer composition layer used to seal electronic devices from adversely affecting the electronic devices. For example, Patent Document 2 discloses a method for manufacturing an organic electroluminescent element in which the sealing body is dried by simultaneously irradiating it with microwaves and far-infrared rays.

[0005] In sealing sheets (especially sealing sheets using hygroscopic fillers), it is necessary to prevent moisture absorption of the polymer composition layer during storage. To prevent moisture absorption of the polymer composition layer, for example, Patent Document 3 describes a water vapor transmission rate of 1 (g / m³). 2 It is disclosed that the polymer composition layer is protected with a first film and a second film that have a lifespan of 24 hours or less. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2017 / 057708 [Patent Document 2] Japanese Patent Publication No. 2006-269247 [Patent Document 3] International Publication No. 2018 / 181426 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Pre-drying of sealing sheets before sealing (hereinafter sometimes referred to as "pre-drying") is desirable to omit from the viewpoint of reducing the manufacturing cost of electronic devices. Furthermore, in sealing sheets having a laminated structure comprising a low-moisture-permeable support, a polymer composition layer, and a low-moisture-permeable protective sheet in this order, it is difficult to pre-dry the polymer composition layer without peeling off the protective sheet. The present invention has been made in view of these circumstances, and the object of the present invention is to provide a sealing sheet in which the moisture content of the polymer composition layer is sufficiently reduced, making pre-drying omittable. [Means for solving the problem]

[0008] The present invention, which can achieve the above-mentioned objectives, is as follows: [1] A sealing sheet having a laminated structure comprising a support, a polymer composition layer, and a protective sheet in this order, The polymer composition layer contains an olefin-based polymer having a crosslinked structure and calcium oxide. The calcium oxide content is 40% of the nonvolatile content of the polymer composition layer by mass. The amount is % or more, and A sealing sheet in which the water content of the polymer composition layer is 500 ppm or less by mass relative to the entire polymer composition layer. [2] The sealing sheet according to [1], wherein the calcium oxide content is 80% by mass or less with respect to 100% by mass of the nonvolatile content of the polymer composition layer. [3] The sealing sheet according to [1] or [2], wherein the olefin polymer having a crosslinked structure is formed from an olefin polymer having carboxyl groups and / or acid anhydride groups and an olefin polymer having epoxy groups. [4] The water vapor permeability of the support and protective sheet is 1 g / m², respectively. 2 A sealing sheet according to any one of the above [1] to [3], which is less than or equal to 24 hours. [5] A sealing sheet according to any one of the above [1] to [4] used for sealing electronic devices. [6] The sealing sheet according to [5], wherein the electronic device is an organic EL device or a solar cell. [7] A polymer composition layer comprising an olefin polymer having a crosslinked structure and calcium oxide, The calcium oxide content is 40% by mass or more relative to 100% by mass of the nonvolatile content of the polymer composition layer, and A polymer composition layer in which the water content of the polymer composition layer is 500 ppm or less on a mass basis relative to the entire polymer composition layer. [8] The polymer composition layer according to [7], wherein the calcium oxide content is 80% by mass or less with respect to 100% by mass of the nonvolatile content of the polymer composition layer. [9] The polymer composition layer according to [7] or [8], wherein the olefin polymer having a crosslinked structure is formed from an olefin polymer having a carboxyl group and / or an acid anhydride group and an olefin polymer having an epoxy group. [Effects of the Invention]

[0009] The polymer composition layer of the sealing sheet of the present invention has a sufficiently low water content, making it possible to omit pre-drying. [Modes for carrying out the invention]

[0010] The present invention provides a sealing sheet having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order. Other layers (for example, a release layer) may be present between the support and the polymer composition layer, and between the polymer composition layer and the protective sheet. The present invention also provides the polymer composition layer itself.

[0011] One of the features of the present invention is that the water content of the polymer composition layer is 500 ppm or less on a mass basis with respect to the entire polymer composition layer. In the sealing sheet of the present invention in which the water content of the polymer composition layer is sufficiently low in this way, pre-drying can be omitted. The lower the water content, the more preferable (ideally 0 ppm), and on a mass basis with respect to the entire polymer composition layer, it is preferably 250 ppm or less, more preferably 100 ppm or less. The water content can be measured as described in the Examples section below.

[0012] One of the features of the present invention is that the polymer composition layer contains a large amount of calcium oxide as a hygroscopic filler. By using a large amount of calcium oxide, the water content of the polymer composition layer can be sufficiently reduced during the production of the sealing sheet (especially during aging).

[0013] In order to sufficiently reduce the water content of the polymer composition layer, the content of calcium oxide is 40% by mass or more, preferably 41% by mass or more, more preferably 42% by mass or more, based on 100% by mass of the non-volatile matter of the polymer composition layer. On the other hand, from the viewpoint of the adhesiveness of the polymer composition layer, the content of calcium oxide is preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less, based on 100% by mass of the non-volatile matter of the polymer composition layer.

[0014] Commercially available products can be used as calcium oxide. Examples of commercially available products include "QC-X" manufactured by Inoue Lime Industry Co., Ltd.; "Moistop #10" manufactured by Sankyo Flour Milling Co., Ltd.; "HAL-G", "HAL-J", "HAL-F" manufactured by Yoshizawa Lime Industry Co., Ltd.; "CaO Nano Powder" manufactured by Filgen Co., Ltd., etc.

[0015] In the present invention, a mixture containing calcium oxide may be used as a hygroscopic filler. Examples of such mixtures include calcined dolomite (a mixture containing calcium oxide and magnesium oxide). Calcined dolomite can be obtained, for example, from Yoshizawa Lime Industry Co., Ltd.

[0016] The particle size of calcium oxide and the particle size of the mixture containing calcium oxide (hereinafter sometimes referred to as "calcium oxide, etc.") are preferably 0.03 to 10 μm, more preferably 0.05 to 5 μm, and even more preferably 0.1 to 3 μm, respectively, in order to prevent calcium oxide, etc. from damaging electronic devices during the sealing process and to enhance the interfacial bonding force between calcium oxide, etc. and the polymer. These particle sizes are the median diameters of the particle size distribution when the particle size distribution is prepared on a volume basis by laser diffraction scattering particle size distribution measurement (JIS Z 8825).

[0017] The polymer composition layer may contain hygroscopic fillers other than calcium oxide (hereinafter sometimes referred to as "other hygroscopic fillers"). Examples of other hygroscopic fillers include semi-calcined hydrotalcite, calcined hydrotalcite, magnesium oxide, molecular sieves, etc. Only one type of other hygroscopic filler may be used, or two or more types may be used in combination. The content of hygroscopic fillers other than calcium oxide is preferably 0 to 40% by mass, preferably 0 to 30% by mass, and more preferably 0 to 20% by mass, based on 100% by mass of the non-volatile content of the polymer composition layer.

[0018] One of the features of the present invention is that the polymer composition layer contains an olefin polymer having a crosslinked structure (hereinafter sometimes referred to as "crosslinked olefin polymer"). By using such a crosslinked olefin polymer, it is possible to obtain a polymer composition layer that can suppress the decrease in adhesive strength even when stored under high humidity and high temperature conditions (i.e., has good resistance to wet heat). The crosslinked olefin polymer may be used alone or in combination of two or more types.

[0019] From the viewpoint of resistance to moist heat, the content of the crosslinked olefin polymer is preferably 1 to 40% by mass, more preferably 2 to 35% by mass, and even more preferably 3 to 30% by mass, based on 100% by mass of the nonvolatile content of the polymer composition layer.

[0020] The crosslinked olefin polymer is preferably formed from an olefin polymer having a carboxyl group and / or an acid anhydride group (i.e., a carbonyloxycarbonyl group (-CO-O-CO-)) and an olefin polymer having an epoxy group, and more preferably from an olefin polymer having an acid anhydride group and an olefin polymer having an epoxy group. The olefin polymer having a carboxyl group and / or an acid anhydride group and the olefin polymer having an epoxy group may be used individually or in combination of two or more.

[0021] The following describes the "olefin polymer" portion of crosslinked olefin polymers, olefin polymers having carboxyl groups and / or acid anhydride groups, and olefin polymers having epoxy groups.

[0022] The olefin units of the olefinic polymer are preferably derived from monoolefins having one olefinic carbon-carbon double bond and / or diolefins having two olefinic carbon-carbon double bonds. Examples of monoolefins include α-olefins such as ethylene, propylene, 1-butene, isobutylene (isobutene), 1-pentene, 1-hexene, 1-heptene, and 1-octene. Examples of diolefins include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethylbutadiene.

[0023] The olefin polymer may be a homopolymer, or a copolymer such as a random copolymer or a block copolymer. Examples of copolymers include copolymers of two or more olefins, and copolymers of olefins with non-olefin monomers such as non-conjugated dienes and styrene. Examples of preferred copolymers include ethylene-non-conjugated diene copolymers, ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, ethylene-butene copolymers, propylene-butene copolymers, propylene-butene-non-conjugated diene copolymers, styrene-isobutylene copolymers, styrene-isobutylene-styrene copolymers, and isobutylene-isoprene copolymers.

[0024] As olefin polymers, butene polymers and propylene polymers are preferred. Here, "butene polymer" refers to a polymer in which the main unit (the unit with the highest content) among all the olefin monomer units constituting the polymer is derived from butene. Examples of butene include 1-butene and isobutylene (isobutene). "Propylene polymer" refers to a polymer in which the main unit (the unit with the highest content) among all the olefin monomer units constituting the polymer is derived from propylene.

[0025] When a butene-based polymer is a copolymer, examples of monomers other than butene include styrene, ethylene, propylene, and isoprene. When a propylene-based polymer is a copolymer, examples of monomers other than propylene include ethylene, butene, and isoprene.

[0026] The olefin polymer is preferably amorphous from the viewpoint of suppressing the decrease in fluidity due to the thickening of the varnish. Here, amorphous means that the olefin polymer does not have a clear melting point, and for example, when the melting point of the olefin polymer is measured by DSC (differential scanning calorimetry), a polymer in which no clear peak is observed can be used.

[0027] Next, olefin polymers having carboxyl groups and / or acid anhydride groups will be described. Examples of acid anhydride groups include groups derived from succinic anhydride, maleic anhydride, and glutaric anhydride. As olefin polymers having carboxyl groups and / or acid anhydride groups, butene polymers having carboxyl groups and / or acid anhydride groups, and propylene polymers having carboxyl groups and / or acid anhydride groups are preferred, with butene polymers having acid anhydride groups and propylene polymers having acid anhydride groups being more preferred.

[0028] The concentration of carboxyl groups in an olefin polymer containing carboxyl groups is preferably 0.05 to 10 mmol / g, and more preferably 0.1 to 5 mmol / g. The concentration of carboxyl groups is obtained from the acid value, which is defined as the number of mg of potassium hydroxide required to neutralize the acid present in 1 g of polymer, according to JIS K 2501.

[0029] The concentration of acid anhydride groups in an olefin polymer containing acid anhydride groups is preferably 0.05 to 10 mmol / g, and more preferably 0.1 to 5 mmol / g. The concentration of acid anhydride groups is obtained from the acid value, which is defined as the number of mg of potassium hydroxide required to neutralize the acid present in 1 g of polymer, according to JIS K 2501.

[0030] In an olefin polymer having both carboxyl groups and acid anhydride groups, the combined concentration of carboxyl groups and acid anhydride groups is preferably 0.05 to 10 mmol / g, and more preferably 0.1 to 5 mmol / g.

[0031] Olefin polymers having carboxyl groups and / or acid anhydride groups can be obtained, for example, by graft modification of an olefin polymer with an unsaturated compound having carboxyl groups and / or acid anhydride groups under radical reaction conditions. Alternatively, olefin polymers having acid anhydride groups can be obtained by radical copolymerization of an unsaturated compound having carboxyl groups and / or acid anhydride groups together with an olefin or the like.

[0032] Commercially available olefin polymers having carboxyl groups and / or acid anhydride groups may be used. Examples of such commercial products include Seikoh PMC's "T-YP279" (maleic anhydride-modified propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 36% by mass, acid anhydride group concentration: 0.464 mmol / g, number average molecular weight: 35,000) and Seikoh PMC's "T-YP312" (maleic anhydride-modified propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 29% by mass, acid anhydride group concentration: 0.464 mmol / g, number average molecular weight: Examples include 60,900), "ER661" from Seikoh PMC (maleic anhydride-modified isobutylene-isoprene random copolymer, acid anhydride group concentration 0.87 mmol / g, number average molecular weight: 39,700), and "HV-300M" from Toho Chemical Industry Co., Ltd. (maleic anhydride-modified liquid polybutene (modified version of "HV-300" (number average molecular weight: 1,400)), number average molecular weight: 2,100, number of carboxyl groups constituting the acid anhydride group: 3.2 per molecule, acid value: 43.4 mgKOH / g, acid anhydride group concentration: 0.77 mmol / g).

[0033] Next, we will describe olefin polymers having epoxy groups. Preferred olefin polymers having epoxy groups include butene polymers and propylene polymers having epoxy groups.

[0034] The concentration of epoxy groups in an olefin polymer containing epoxy groups is preferably 0.05 to 10 mmol / g, and more preferably 0.1 to 5 mmol / g. The epoxy group concentration can be determined from the epoxy equivalent obtained according to JIS K 7236-1995.

[0035] Olefin polymers having epoxy groups are, for example, unsaturated compounds having epoxy groups such as glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, and allyl glycidyl ether, and can be obtained by graft modification of olefin polymers under radical reaction conditions. Alternatively, olefin polymers having epoxy groups can be obtained by radical copolymerization of an unsaturated compound having epoxy groups together with an olefin or the like.

[0036] Commercially available olefin polymers containing epoxy groups may be used. For example, "T-YP341" from Seikoh PMC (glycidyl methacrylate-modified propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 29% by mass, epoxy group concentration: 0.638 mmol / g, number average molecular weight: 155) is available. Examples include "T-YP276" (glycidyl methacrylate-modified propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 36% by mass, epoxy group concentration: 0.638 mmol / g, number average molecular weight: 57,000) manufactured by Seikoh PMC, "T-YP313" (glycidyl methacrylate-modified propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 29% by mass, epoxy group concentration: 0.638 mmol / g, number average molecular weight: 155,000) manufactured by Seikoh PMC, and "ER850" (glycidyl methacrylate-modified isobutylene-isoprene random copolymer, epoxy group concentration: 0.654 mmol / g, number average molecular weight: 99,200) manufactured by Seikoh PMC.

[0037] The amounts of olefin polymer having carboxyl groups and olefin polymer having epoxy groups used are not particularly limited as long as a crosslinking structure can be formed, but the ratio of the amount of epoxy groups (mol) to the amount of carboxyl groups (mol) (i.e., amount of epoxy groups (mol): amount of carboxyl groups (mol)) is preferably 100:10 to 100:500, more preferably 100:25 to 100:475, and even more preferably 100:40 to 100:450.

[0038] The amount of olefin polymer having acid anhydride groups and olefin polymer having epoxy groups used is not particularly limited as long as a crosslinking structure can be formed, but the ratio of the amount of epoxy groups (mol) to the amount of acid anhydride groups (mol) (i.e., the amount of epoxy groups (mol): amount of acid anhydride groups (mol)) is preferably 100:10 to 100:500, more preferably 100:25 to 100:475, and even more preferably 100:40 to 100:450.

[0039] The amount of olefin polymer having both carboxyl groups and acid anhydride groups and olefin polymer having epoxy groups used is not particularly limited as long as a crosslinking structure can be formed, but the ratio of "amount of epoxy groups (mol)" to "total amount of carboxyl groups (mol) and acid anhydride groups (mol)" (i.e., amount of epoxy groups (mol):(amount of carboxyl groups (mol) + amount of acid anhydride groups (mol))) is preferably 100:10 to 100:500, more preferably 100:25 to 100:475, and even more preferably 100:40 to 100:450.

[0040] The polymer composition layer preferably contains an olefin polymer that does not have a crosslinked structure (hereinafter sometimes referred to as "non-crosslinked olefin polymer") from the viewpoint of adhesiveness and flexibility. One type of non-crosslinked olefin polymer may be used, or two or more types may be used in combination. The description of the "olefin polymer" portion of the non-crosslinked olefin polymer is the same as the description of the "olefin polymer" portion of the crosslinked olefin polymer, etc., described above.

[0041] From the viewpoint of the adhesiveness and flexibility of the polymer composition layer, the content of the non-crosslinked olefin polymer is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and even more preferably 15 to 40% by mass, based on 100% by mass of the nonvolatile content of the polymer composition layer.

[0042] Commercially available non-crosslinked olefin polymers may be used. Examples of such commercially available products include ENEOS's "HV-300" (liquid polybutene, number average molecular weight 1,400), ENEOS's "HV-1900" (liquid polybutene, number average molecular weight: 2,900), Mitsui Chemicals' "X1102C" (propylene-butene random copolymer, amount of butene units per total of propylene and butene units: 29% by mass), BASF's "Opanol B100" (polyisobutylene, viscosity average molecular weight: 1,110,000), BASF's "N50SF" (polyisobutylene, viscosity average molecular weight: 400,000), ENEOS's "Tetrax 3T" (polyisobutylene, viscosity average molecular weight: 30,000), and ENEOS's "Tetrax 6T" (polyisobutylene, viscosity average molecular weight: 60,000). It can be done.

[0043] The number-average molecular weights of the olefin polymers having acid anhydride groups, olefin polymers having epoxy groups, and non-crosslinked olefin polymers described above are preferably 1,000,000 or less, more preferably 750,000 or less, even more preferably 500,000 or less, still more preferably 400,000 or less, even more preferably 300,000 or less, and particularly preferably 200,000 or less, from the viewpoint of good coatability of the varnish of the polymer composition. On the other hand, from the viewpoint of preventing repulsion of the varnish of the polymer composition during coating, exhibiting sealing performance of the formed polymer composition layer, and improving mechanical strength, the number-average molecular weight is preferably 1,000 or more, and more preferably 2,000 or more. The number-average molecular weight in this invention is measured by gel permeation chromatography (GPC) (polystyrene equivalent). Specifically, the number-average molecular weight can be calculated using the GPC method by measuring with a Shimadzu LC-9A / RID-6A measuring instrument, a Showa Denko Shodex K-800P / K-804L / K-804L column, and toluene or the like as the mobile phase, at a column temperature of 40°C, and then using a calibration curve for standard polystyrene.

[0044] The polymer composition layer may contain components other than those described above (hereinafter sometimes referred to as "other components"), as long as they do not impede the effects of the present invention. Examples of other components include tackifiers, curing accelerators, antioxidants, and plasticizers. These may be used individually or in combination of two or more.

[0045] Tackifiers are components that impart tackiness to polymer composition layers. Examples of tackifiers include rosin resins, terpene resins, modified terpene resins (hydrogenated terpene resins, terpene-phenol copolymer resins, aromatically modified terpene resins, etc.), petroleum resins (aliphatic petroleum resins, hydrogenated petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, copolymer petroleum resins), coumarone-indene resins, alkylphenol resins, xylene resins, and the like.

[0046] Commercially available tackifiers can be used. Examples of such commercially available products include: Rosin-based resins such as Pine Crystal ME-H, Pine Crystal ME-D, Pine Crystal ME-G, Pine Crystal KR-85, Pine Crystal KE-311, Pine Crystal KE-359, Pine Crystal D-6011, Pine Crystal PE-590, Pine Crystal KE-604, and Pine Crystal PR-580 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0047] Examples of terpene resins include YS Resin PX1000, YS Resin PX1150, YS Resin PX1150N, YS Resin PX1250, YS Resin TH130, YS Resin TR105, YS Resin LP, and YS Resin CP (all manufactured by Yasuhara Chemical Co., Ltd.).

[0048] Examples of hydrogenated terpene resins include the Clearon P, Clearon M, and Clearon K series (all manufactured by Yasuhara Chemical Co., Ltd.).

[0049] Examples of terpene phenol copolymer resins include YS Polystar 2000, Polystar U, Polystar T, Polystar S, and Mighty Ace G (all manufactured by Yasuhara Chemical Co., Ltd.).

[0050] Examples of aromatically modified terpene resins include YS Resin TO85, YS Resin TO105, YS Resin TO115, and YS Resin TO125 (all manufactured by Yasuhara Chemical Co., Ltd.).

[0051] Examples of hydrogenated petroleum resins include the Escorez 5300 series and 5600 series (both manufactured by ExxonMobil); T-REZ OP501, T-REZ PR803, T-REZ HA085, T-REZ HA103, T-REZ HA105, T-REZ HA125 (all hydrogenated dicyclopentadiene petroleum resins, manufactured by ENEOS); Quintone 1325, Quintone 1345 (both manufactured by Nippon Zeon Co., Ltd.); iMarb S-100, iMarb S-110, iMarb P-100, iMarb P-125, iMarb P-140 (all hydrogenated dicyclopentadiene petroleum resins, manufactured by Idemitsu Kosan Co., Ltd.); Alcon P-90, Alcon P-100, Alcon P-115, Alcon P-125, Alcon P-140, Alcon Examples include M-90, Alcon M-100, Alcon M-115, Alcon M-135, and TFS13-030 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0052] Examples of aromatic petroleum resins include ENDEX155 (manufactured by Eastman Corporation); Neopolymer L-90, Neopolymer 120, Neopolymer 130, Neopolymer 140, Neopolymer 150, Neopolymer 170S, Neopolymer 160, Neopolymer E-100, Neopolymer E-130, Neopolymer M-1, Neopolymer S, Neopolymer S100, Neopolymer 120S, Neopolymer 130S, Neopolymer EP-140 (all manufactured by ENEOS Corporation); Petocol LX, Petocol 120, Petocol 130, Petocol 140 (all manufactured by Tosoh Corporation); T-REZ RB093, T-REZ RC100, T-REZ RC115, T-REZ RC093, T-REZ RE100 (all manufactured by ENEOS Corporation).

[0053] Examples of copolymerized petroleum resins include T-REZ HB103, T-REZ HB125, T-REZ PR801, T-REZ PR802, and T-REZ RD104 (all manufactured by ENEOS Corporation); Petrotac 60, Petrotac 70, Petrotac 90, Petrotac 90HS, Petrotac 90V, and Petrotac 100V (all manufactured by Tosoh Corporation); and Quintone D100 (manufactured by Nippon Zeon Corporation).

[0054] The softening point of the tackifier is preferably 50 to 200°C, more preferably 90 to 180°C, and even more preferably 100 to 150°C, from the viewpoint of the heat resistance of the polymer composition layer. The softening point is measured by the ring-and-ball method in accordance with JIS K2207.

[0055] The content of the tackifier is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, and even more preferably 0 to 30% by mass, based on 100% by mass of the nonvolatile content of the polymer composition layer, from the viewpoint of the tackiness and sealing properties of the polymer composition layer.

[0056] Examples of curing accelerators include imidazole compounds, tertiary and quaternary amine compounds, dimethylurea compounds, and organophosphine compounds.

[0057] Examples of imidazole compounds include 1H-imidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 2,4-diamino-6-(2'-undecylimidazolyl- (1'))-ethyl-s-triazine, 2-phenyl-4,5-bis(hydroxymethyl)imidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-phenylimidazole, 2-dodecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4-diamino-6-(2'-methylimidazolyl-(1 Examples include '))-ethyl-s-triazine and 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine isocyanuric acid adduct. Specific examples of imidazole compounds include Cureazole 2MZ, 2P4MZ, 2E4MZ, 2E4MZ-CN, C11Z, C11Z-CN, C11Z-CNS, C11Z-A, 2PHZ, 1B2MZ, 1B2PZ, 2PZ, C17Z, 1.2DMZ, 2P4MHZ-PW, 2MZ-A, and 2MA-OK (all manufactured by Shikoku Chemicals Co., Ltd.).

[0058] There are no particular restrictions on tertiary and quaternary amine compounds, but examples include quaternary ammonium salts such as tetramethylammonium bromide and tetrabutylammonium bromide; diazabicyclo compounds such as DBU (1,8-diazabicyclo[5.4.0]undecene-7), DBN (1,5-diazabicyclo[4.3.0]nonene-5), DBU-phenol salt, DBU-octylate, DBU-p-toluenesulfonate, DBU-formate, and DBU-phenol novolac resin salt; tertiary amines such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol (TAP) or their salts, and dimethylurea compounds such as aromatic dimethylurea and aliphatic dimethylurea.

[0059] Examples of dimethylurea compounds include aromatic dimethylureas such as DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and U-CAT3512T (manufactured by Sunapro Co., Ltd.), and aliphatic dimethylureas such as U-CAT3503N (manufactured by Sunapro Co., Ltd.). Among these, aromatic dimethylureas are preferred due to their curability.

[0060] Examples of organic phosphine compounds include triphenylphosphine, tetraphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tri-tert-butylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, and triphenylphosphinetriphenylborane. Specific examples of organic phosphine compounds include TPP, TPP-MK, TPP-K, TTBuP-K, TPP-SCN, and TPP-S (all manufactured by Hokko Chemical Industry Co., Ltd.).

[0061] When a curing accelerator is used, its content is preferably 0.001 to 5% by mass, more preferably 0.001 to 2.5% by mass, and even more preferably 0.001 to 1% by mass, based on 100% by mass of the nonvolatile content of the polymer composition layer, in order to promote the formation of olefin-based polymers having a cross-linked structure.

[0062] In the present invention, there are no particular limitations on the antioxidant, and known antioxidants can be used. When an antioxidant is used, its content is preferably 0.01 to 5% by mass, more preferably 0.05 to 2.5% by mass, and even more preferably 0.1 to 2% by mass, based on 100% by mass of the nonvolatile content of the polymer composition layer.

[0063] Examples of plasticizers include mineral oils such as paraffinic process oils, naphthenic process oils, liquid paraffin, and petrolatum, as well as vegetable oils such as castor oil, cottonseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, and olive oil.

[0064] The sealing sheet of the present invention has a laminated structure comprising a support, a polymer composition layer, and a protective sheet in this order. Examples of the support and protective sheet include polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; cycloolefin polymers; polyesters such as polyethylene terephthalate (hereinafter sometimes referred to as "PET") and polyethylene naphthalate; polycarbonate; and plastic films such as polyimide. The support and protective sheet may both be single-layer films or laminated films.

[0065] In the protective sheet, it is preferable that the surface in contact with the polymer composition layer is treated for mold release. On the other hand, the support may or may not be treated for mold release. Examples of mold release treatments include those using release agents such as silicone resin-based release agents, alkyd resin-based release agents, and fluororesin-based release agents.

[0066] The thickness of the support and protective sheet is not particularly limited, but from the viewpoint of handling the sealing sheet, etc., it is preferably 10 to 150 μm, more preferably 20 to 100 μm, respectively. If the support and protective sheet are laminated films, the thickness is the thickness of the laminated film. On the other hand, the thickness of the polymer composition layer is preferably 5 to 200 μm, more preferably 5 to 150 μm, and even more preferably 5 to 100 μm, from the viewpoint of sealing properties, etc.

[0067] The water vapor transmission rate (hereinafter sometimes referred to as "WVTR") of the support and protective sheet is preferably 1 (g / m²), respectively. 2 The water vapor permeability (g / m³) of the sheet is less than or equal to 24 hours. 2 " / 24hr)" refers to the following conditions for temperature and humidity, over an area of ​​1 m² 2 This refers to the amount of water vapor (g) that passes through the sheet in 24 hours. A water vapor transmission rate of 1 (g / m³) is considered to be 1. 2 By using a low-moisture-permeability support and protective sheet with a moisture permeability of 0.5 / 24hr or less, moisture absorption of the polymer composition layer can be prevented during storage of the sealing sheet. However, using a low-moisture-permeability support and protective sheet generally makes pre-drying of the sealing sheet difficult. In this regard, in the present invention, as described above, by using a large amount of calcium oxide, the moisture content of the polymer composition layer can be sufficiently reduced during the manufacturing of the sealing sheet (especially during aging), thus eliminating the need for pre-drying of the sealing sheet.

[0068] The water vapor transmission rate (g / m³) of the sheet. 2 The water vapor transmission rate ( / 24hr) can be measured using a MOCON PERMATRAN series water vapor transmission rate analyzer (compliant with ISO 15106-2 and JIS K7129B). Specifically, the sheet is measured at 50cm². 2 After cutting the material and setting it in a jig using silicone grease, the temperature is adjusted to 40 degrees Celsius and the humidity to 90% RH using ultrapure water, and the water vapor transmission rate is measured until it reaches a steady state.

[0069] As the low moisture permeability support and the low moisture permeability protective sheet, for example, a film having a barrier layer, or a laminated film of a film having a barrier layer and another film can be used. Examples of the barrier layer include inorganic films such as a silica vapor deposition film, a silicon nitride film, and a silicon oxide film. The barrier layer may be composed of a plurality of layers of a plurality of inorganic films (for example, a silica vapor deposition film). Further, the barrier layer may be composed of an organic substance and an inorganic substance, or may be a composite multilayer of an organic layer and an inorganic film.

[0070] As the film having a barrier layer, for example, a high-barrier plastic film having a WVTR of 0.0005 (g / m 2 / 24 hr) or less can be used. Examples of the high-barrier plastic film include those produced by laminating a single layer or multiple layers of an inorganic film such as silicon oxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon oxynitride, SiCN, amorphous silicon, etc. on the surface of a plastic film by chemical vapor deposition (for example, chemical vapor deposition by heat, plasma, ultraviolet rays, vacuum heat, vacuum plasma or vacuum ultraviolet rays), or physical vapor deposition (for example, vacuum evaporation method, sputtering method, ion plating method, laser deposition method, molecular beam epitaxy method, etc.) (see, for example, JP-A-2016-185705, Patent No. 5719106, Patent No. 5712509, Patent No. 5292358, etc.). In order to prevent cracking of the inorganic film, it is preferable to alternately laminate the inorganic film and a transparent planarizing layer (for example, a transparent plastic layer).

[0071] Also, as the film having a barrier layer, for example, a WVTR of 0.01 (g / m 2 / 24 hr) or more and 1 (g / m 2A medium-barrier plastic film with a lifespan of 24 hours or less can be used. Examples of medium-barrier plastic films include those manufactured by methods such as depositing an inorganic film containing inorganic substances such as silicon dioxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon oxide nitride, SiCN, and amorphous silicon onto the substrate surface as a barrier layer, or by applying a coating liquid consisting of a metal oxide and an organic resin having barrier properties to the substrate and drying it (see, for example, Japanese Patent Publication No. 2013-108103 and Japanese Patent No. 4028353).

[0072] Commercially available films with a barrier layer may be used. Examples of commercially available medium-barrier plastic films include Kuraray's "Clarista CI," Mitsubishi Chemical's "Tech Barrier HX," "Tech Barrier LX," and "Tech Barrier L," Dai Nippon Printing's "IB-PET-PXB," and Toppan Printing's "GL, GX series." Examples of commercially available high-barrier plastic films include Mitsubishi Chemical's "X-BARRIER."

[0073] The sealing sheet and polymer composition layer of the present invention can be manufactured, for example, by (1) dissolving the above-mentioned components in an organic solvent to prepare a polymer composition varnish, (2) applying the obtained varnish to a support to form a coating film, (3) drying the obtained coating film to form a polymer composition layer (dried coating film), (4) laminating a protective sheet onto the obtained polymer composition layer to form a laminate, and (5) reducing the water content of the polymer composition layer by heating the obtained laminate during aging.

[0074] Examples of organic solvents that can be used in the preparation of varnish include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; cellosolves such as cellosolve; carbitols such as butyl carbitol; aromatic hydrocarbons such as toluene and xylene; amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and others. Only one organic solvent may be used, or two or more may be used in combination. Commercially available organic solvents may also be used. Examples of such commercially available products include "Swazol" manufactured by Maruzen Petrochemical Co., Ltd. and "Ipsol" manufactured by Idemitsu Kosan Co., Ltd. The varnish may be applied by known methods (for example, by using a die coater), and there are no particular limitations on the application method.

[0075] Drying of the coating film is preferably carried out by heating in order to form an olefin-based polymer having a crosslinked structure. The drying temperature of the coating film is preferably 50 to 200°C, more preferably 80 to 150°C, and the drying time is preferably 1 to 60 minutes, more preferably 10 to 30 minutes. Drying may be carried out under normal pressure or under reduced pressure.

[0076] Lamination of a protective sheet onto a polymer composition layer can be carried out using known equipment. Examples of such equipment include roll laminators, presses, and vacuum laminators.

[0077] The aging temperature of the laminate is preferably 80 to 200°C, more preferably 100 to 150°C, and the duration is preferably 10 to 240 minutes, more preferably 30 to 180 minutes.

[0078] The sealing sheet of the present invention can be used to seal electronic devices. Examples of electronic devices include organic EL devices, solar cells, and sensor devices. More preferably, the electronic device is a moisture-sensitive device such as an organic EL device or a solar cell. Furthermore, the sealing sheet of the present invention can be used to seal conductive substrates and the like. [Examples]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the above and below, and all such modifications are included in the technical scope of the present invention. In addition, unless otherwise specified, "parts" and "%" in the amounts of components and copolymer units mean "parts by mass" and "mass%", respectively.

[0080] <Ingredients> The components used in the examples and comparative examples are shown below. (Olefin polymers) "T-YP341" (manufactured by Seikoh PMC, glycidyl methacrylate-modified propylene-butene random copolymer, propylene units / butene units: 71% / 29%, epoxy group concentration: 0.64 mmol / g, number average molecular weight: 155,000) "HV-300M" (manufactured by Toho Chemical Industry Co., Ltd., maleic anhydride-modified liquid polybutene, acid anhydride group concentration: 0.77 mmol / g, number average molecular weight: 2,100) "HV-1900" (manufactured by ENEOS Corporation, liquid polybutene, number average molecular weight: 2,900)

[0081] (Moisture-absorbing filler) Calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) Calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 1.8 μm) Semi-calcined hydrotalcite (Kyowa Chemical Industry Co., Ltd. "DHT-4C", particle size (median diameter): 400 nm, BET specific surface area: 15 m²) 2 / g) Calcined hydrotalcite (KW2200 manufactured by Kyowa Chemical Industry Co., Ltd., particle size (median diameter): 400 nm, BET specific surface area: 190 m²) 2 / g) Magnesium oxide (DIPSERMAG, manufactured by Tateho Chemical Industry Co., Ltd.) Molecular sieve 4A (manufactured by Union Showa Co., Ltd.)

[0082] (Adhesion agent) "T-REZ HA105" (manufactured by ENEOS, hydrogenated alicyclic petroleum resin, softening point: 105℃)

[0083] (Antioxidant) "Irganox 1010" (BASF, hindered phenol antioxidant)

[0084] (Curing accelerator) 2,4,6-Tris(dimethylaminomethyl)phenol (hereinafter abbreviated as "TAP") (manufactured by Nuurion Co., Ltd.)

[0085] <Example 1> Varnishes with the mixing ratios shown in the table below were prepared using the following procedure, and sealing sheets were made using the obtained varnishes. The amount (parts) of each component listed in the table below indicates the amount of non-volatile content of each component in the varnish. The table below also shows the amount of hygroscopic filler added relative to 100% by mass of the non-volatile content of the varnish.

[0086] Specifically, hydrogenated alicyclic petroleum resin (tackifier, ENEOS Corporation's "T-REZ HA1") A mixture was obtained by dispersing maleic anhydride-modified liquid polybutene (HV-300M, manufactured by Toho Chemical Industry Co., Ltd.), liquid polybutene (HV-1900, manufactured by ENEOS Corporation), and calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) in a three-roll mixer. To the obtained mixture, a Swazole solution of glycidyl methacrylate-modified propylene-butene random copolymer (T-YP341, manufactured by Seikoh PMC Co., Ltd.) (non-volatile content: 15%), a hindered phenol antioxidant (Irganox 1010, manufactured by BASF Corporation), a curing accelerator (TAP, manufactured by Kayaku Nurion Co., Ltd.), and toluene were added, and the resulting mixture was uniformly dispersed in a high-speed rotary mixer to obtain a polymer composition varnish (non-volatile content: 63%).

[0087] A polyethylene terephthalate film (Toyo Cloth Co., Ltd. "SP4020", PET film thickness: 50 μm) with one side treated with a silicone-based release agent and a low-permeability polyethylene terephthalate film (Mitsubishi Chemical Corporation "Tech Barrier HX", PET film thickness: 12 μm) were laminated together so that the side of the SP4020 not treated with the silicone-based release agent was in contact with the Tech Barrier HX to create a laminated film, which was then used as a support and protective sheet for a sealing sheet (laminated film thickness: 62 μm, laminated film water vapor permeability: 0.12 (g / m²)). 2 / 24hr)). Hereinafter, the "surface of the laminated film treated with a silicone-based release agent" will be referred to as the "release-treated surface".

[0088] A polymer composition varnish was uniformly applied to the release-treated surface of the first laminated film using a die coater, and the film was heated at 140°C for 30 minutes to form a polymer composition layer containing an olefin-based polymer having a crosslinked structure.

[0089] Subsequently, a second laminated film was laminated so that its release-treated surface and the polymer composition layer were in contact, and then heated (aged) at 130°C for 60 minutes to reduce the water content of the polymer composition layer, thereby obtaining a sealing sheet (polymer composition layer thickness: 50 μm) having a laminated structure of "support (laminated film) / polymer composition layer / protective sheet (laminated film)".

[0090] <Example 2> Except for changing the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) used from 200 parts to 260 parts, a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0091] <Example 3> Except for changing the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) used from 200 parts to 390 parts, a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0092] <Example 4> Except for changing calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 1.8 μm), a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0093] <Comparative Example 1> Except for changing the hygroscopic filler from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to semi-calcined hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., "DHT-4C"), a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0094] <Comparative Example 2> Except for changing the hygroscopic filler from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to calcined hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., "KW2200"), a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0095] <Comparative Example 3> Except for changing the hygroscopic filler from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to magnesium oxide ("DISPERMAG" manufactured by Tateho Chemical Industry Co., Ltd.), a polymer composition varnish and a sealing sheet having a polymer composition layer with a thickness of 50 μm were prepared in the same manner as in Example 1.

[0096] <Comparative Example 4> Except for changing the hygroscopic filler from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to molecular sieve 4A (manufactured by Union Showa Co., Ltd.), a sealing sheet having a polymer composition varnish and a polymer composition layer with a thickness of 50 μm was prepared using the same method as in Example 1.

[0097] <Comparative Example 5> Except for changing the aging conditions to 130°C and 24 hours, a polymer composition varnish and a sealing sheet having a polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 1.

[0098] <Comparative Example 6> Except for changing the aging conditions to 130°C and 24 hours, a polymer composition varnish and a sealing sheet having a polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 2.

[0099] <Comparative Example 7> Except for changing the aging conditions to 130°C and 24 hours, a polymer composition varnish and a sealing sheet having a polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 3.

[0100] <Moisture content of the polymer composition layer> The sealing sheets prepared in the examples and comparative examples were cut to a length of 70 mm and a width of 40 mm. The support and protective sheet were peeled off from the cut sealing sheets, and the resulting polymer composition layer was folded and placed in a dry screw vial (VABH17, manufactured by Mitsubishi Chemical Analytec Co., Ltd.). This was then placed in an electric furnace (VA-236S, manufactured by Mitsubishi Chemical Analytec Co., Ltd.) directly connected to a Karl Fischer analyzer (CA310, manufactured by Mitsubishi Chemical Analytec Co., Ltd.). The electric furnace temperature was raised to 250°C in an N2 airflow, and the water detached from the sample was collected in a Karl Fischer analyzer solution. The mass of the water was measured using a standard method. From the measured mass of water, the water content (ppm) of the polymer composition layer was calculated based on the mass relative to the entire polymer composition layer. The results are shown in the table below.

[0101] The water vapor penetration barrier properties of the polymer composition layers of each sealing sheet obtained in the examples and comparative examples were evaluated by the following method.

[0102] <Method for evaluating water vapor barrier properties> The support comprises aluminum foil and polyethylene terephthalate film. A composite film (Tokai Toyo Aluminum Sales Co., Ltd. "PET-Tsuki AL1N30", aluminum foil thickness 30 μm, PET film thickness 25 μm) was prepared (water vapor transmission rate of the composite film: 0.001 (g / m³) 2 / 24hr) or less).

[0103] A test sheet having a laminated structure of "support (composite film) / polymer composition layer / protective sheet (laminated film)" was obtained in the same manner as in each example and comparative example, except that the aforementioned composite film was used as the support. The polymer composition layer was formed on the aluminum foil of the composite film.

[0104] A 50mm x 50mm square glass plate made of alkali-free glass was prepared. This glass plate was washed with boiled isopropyl alcohol for 5 minutes and dried at 150°C for more than 30 minutes.

[0105] Calcium was deposited onto one side of the dried glass plate using a mask that covered the peripheral area 0mm to 2mm from the edge of the glass plate. As a result, a 200nm thick calcium film (purity: 99.8%) was formed on the central portion of one side of the glass plate, excluding the peripheral area 0mm to 2mm from the edge.

[0106] In a nitrogen atmosphere, the polymer composition layer of the test sheet described above and the calcium film side of the glass plate were bonded together using a thermal laminator (Fujiplas Corporation's "Lamipacker DAiSY A4 (LPD2325)") to obtain a laminate. This laminate was used as an evaluation sample.

[0107] Generally, when calcium comes into contact with water, it becomes transparent as calcium oxide. Furthermore, in the aforementioned evaluation sample, since the glass plate and aluminum foil have sufficiently high water vapor penetration barrier properties, moisture usually moves in the in-plane direction (perpendicular to the thickness direction) through the edges of the polymer composition layer and reaches the calcium film. When moisture reaches the calcium film, it gradually oxidizes from the edges and becomes transparent, so a shrinkage of the calcium film is observed. Therefore, moisture penetration into the evaluation sample can be evaluated by measuring the sealing distance (mm) from the edge of the evaluation sample to the calcium film. Thus, the evaluation sample containing the calcium film can be used as a model for electronic devices.

[0108] First, the initial sealing distance X2 (mm) from the edge of the evaluation sample to the edge of the calcium film was measured using a microscope (Mitutoyo "Measuring Microscope MF-U").

[0109] Next, the evaluation sample was placed in a constant temperature and humidity chamber set to 85°C and 85% RH. The evaluation sample was removed from the chamber when the sealing distance X1 (mm) between the edge of the evaluation sample and the edge of the calcium film increased by 0.1 mm compared to the initial sealing distance X2. The time from when the evaluation sample was placed in the chamber to when it was removed was defined as the decrease start time t (hours). This decrease start time t is calculated from the time T when the evaluation sample was placed in the chamber. P1 Therefore, at the point T when the sealing distance X1 (mm) between the end of the evaluation sample stored in the constant temperature and humidity chamber and the end of the calcium membrane becomes "X2 + 0.1 mm" P2 This corresponds to the time until [a certain point].

[0110] The sealing distance X1 and the decrease start time t were applied to Fick's diffusion equation in equation (1) to calculate the constant K as a water vapor infiltration barrier parameter.

[0111]

number

[0112] Using the obtained constant K, the ability of the polymer composition layer to suppress moisture penetration (water vapor penetration barrier property) was evaluated according to the following criteria. A smaller value of constant K indicates higher water vapor penetration barrier property. Note that "hr" below refers to "time". The results are shown in the table below. Note that "(cm / hr^0.5)" in the table below refers to "(cm / hr 0.5 ) means ". (Standards for water vapor barrier properties) ○: Constant K is 0.02 cm / hr 0.5 less than ×: Constant K is 0.02 cm / hr 0.5 That's all.

[0113] [Table 1]

[0114] [Table 2]

[0115] [Table 3]

[0116] As shown in the table above, in Examples 1 to 4, in which a large amount of calcium oxide was used and an olefin-based polymer having a crosslinked structure was formed, a polymer composition layer with low water content and excellent water vapor penetration barrier properties was formed. On the other hand, as a hygroscopic filler, semi-calcined hydro In Comparative Examples 1-7, which used talcite, calcined hydrotalcite, magnesium oxide, or molecular sieve 4A, the water content of the polymer composition layer could not be sufficiently reduced. In particular, in Comparative Examples 5-7, even after aging for 24 hours, the water content of the polymer composition layer could not be sufficiently reduced. [Industrial applicability]

[0117] The sealing sheet of the present invention is useful for sealing electronic devices (e.g., organic EL devices, solar cells, sensor devices, etc.), conductive substrates, and the like.

Claims

1. A method for manufacturing a sealing sheet having a laminated structure comprising a support, a polymer composition layer, and a protective sheet in this order, The polymer composition layer comprises an olefin polymer having a crosslinked structure, an olefin polymer not having a crosslinked structure, and calcium oxide. The content of the olefin polymer having a crosslinked structure is 1 to 40% by mass relative to 100% by mass of the nonvolatile content of the polymer composition layer. The content of olefin-based polymers that do not have a cross-linked structure is 5 to 50% by mass relative to 100% by mass of the non-volatile content of the polymer composition layer. The calcium oxide content is 40% by mass or more and 80% by mass or less based on 100% by mass of the nonvolatile content of the polymer composition layer, and The water content of the polymer composition layer is 500 ppm or less by mass relative to the entire polymer composition layer. (1) A step of preparing a varnish for a polymer composition by dissolving an olefin polymer having a crosslinked structure, an olefin polymer not having a crosslinked structure, and calcium oxide in an organic solvent. (2) A step of applying the obtained varnish onto a support to form a coating film, (3) A step of drying the obtained coating film to form a polymer composition layer (dried coating film), and (4) Step of laminating a protective sheet onto the obtained polymer composition layer to form a laminate. A manufacturing method that includes this.

2. (5) A step of reducing the water content of the polymer composition layer to 500 ppm or less by heating the obtained laminate during aging. The manufacturing method according to claim 1, further comprising:

3. The manufacturing method according to claim 1 or 2, wherein the olefin polymer having a crosslinked structure is formed from an olefin polymer having a carboxyl group and / or an acid anhydride group and an olefin polymer having an epoxy group.

4. The water vapor permeability of the support and protective sheet is 1 (g / m²), respectively. ２ The manufacturing method according to claim 1 or 2, wherein the time is less than or equal to 24 hours.

5. The manufacturing method according to claim 1 or 2, wherein the sealing sheet is used for sealing an electronic device.

6. The manufacturing method according to claim 5, wherein the electronic device is an organic EL device or a solar cell.

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