JP7528605B2 - Encapsulating sheet and polymer composition layer - Google Patents

Description

The present invention relates to an encapsulating sheet and a polymer composition layer that are useful for encapsulating electronic devices.

To protect electronic devices such as organic electroluminescence (EL) devices and solar cells from moisture, the electronic devices are encapsulated using a polymer composition layer.

As a polymer composition layer suitable for sealing electronic devices, one containing a hygroscopic filler is known. For example, Patent Document 1 discloses a sealing sheet composed of a support and a polymer composition layer containing a hygroscopic metal hydroxide.

In the case of an encapsulating sheet (particularly an encapsulating sheet using a hygroscopic filler), the encapsulating sheet is dried before encapsulation to prevent moisture present on the surface and inside of the polymer composition layer used to encapsulate the electronic device from adversely affecting the electronic device. For example, Patent Document 2 discloses a method for manufacturing an organic electroluminescence element in which the encapsulated body is simultaneously irradiated with microwaves and far infrared rays to dry the encapsulated body.

In an encapsulating sheet (particularly an encapsulating sheet using a hygroscopic filler), it is necessary to prevent the polymer composition layer from absorbing moisture during storage. In order to prevent the polymer composition layer from absorbing moisture, for example, Patent Document 3 discloses protecting the polymer composition layer with a first film and a second film having a water vapor transmission rate of 1 (g/ ^m2 /24hr) or less.

International Publication No. 2017/057708 JP 2006-269247 A International Publication No. 2018/181426

It is desirable to omit the drying of the encapsulating sheet before encapsulation (hereinafter sometimes referred to as "pre-drying") from the viewpoint of reducing the manufacturing costs of electronic devices. Furthermore, in an encapsulating sheet having a laminated structure including 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 light of these circumstances, and an object of the present invention is to provide an encapsulating sheet in which the moisture content of the polymer composition layer is sufficiently reduced, allowing pre-drying to be omitted.

The present invention capable of achieving the above object is as follows.
[1] A sheet for encapsulation having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order,
the polymer composition layer comprises an olefin-based polymer having a crosslinked structure and calcium oxide;
A sealing sheet, wherein the content of calcium oxide is 40% by mass or more relative to 100% by mass of the nonvolatile content of the polymer composition layer, and the moisture content of the polymer composition layer is 500 ppm or less on a mass basis with respect to the entire polymer composition layer.
[2] The sealing sheet according to the above [1], wherein the content of calcium oxide is 80 mass% or less relative to 100 mass% of the nonvolatile content of the polymer composition layer.
[3] The sealing sheet according to the above [1] or [2], wherein the olefin-based polymer having a crosslinked structure is formed from an olefin-based polymer having a carboxy group and/or an acid anhydride group, and an olefin-based polymer having an epoxy group.
[4] The encapsulating sheet according to any one of the above [1] to [3], wherein the support and the protective sheet each have a water vapor permeability of 1 (g/m ² /24 hr) or less.
[5] The encapsulating sheet according to any one of [1] to [4] above, which is used for encapsulating an electronic device.
[6] The encapsulating sheet according to the above [5], wherein the electronic device is an organic EL device or a solar cell.
[7] A polymer composition layer comprising an olefin-based polymer having a crosslinked structure and calcium oxide,
A polymer composition layer having a calcium oxide content of 40 mass % or more relative to 100 mass % of the nonvolatile content of the polymer composition layer, and a moisture content of the polymer composition layer of 500 ppm or less based on the mass of the entire polymer composition layer.
[8] The polymer composition layer according to [7], wherein the content of calcium oxide is 80% by mass or less relative 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-based polymer having a crosslinked structure is formed from an olefin-based polymer having a carboxy group and/or an acid anhydride group, and an olefin-based polymer having an epoxy group.

The polymer composition layer of the sealing sheet of the present invention has a sufficiently low moisture content, making it possible to omit pre-drying.

The present invention provides an encapsulating sheet having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order. Another layer (e.g., 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.

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

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 moisture content of the polymer composition layer can be sufficiently reduced during the production of the sealing sheet (particularly during aging).

In order to sufficiently reduce the moisture content of the polymer composition layer, the content of calcium oxide is 40% by mass or more, preferably 41% by mass or more, and more preferably 42% by mass or more, based on 100% by mass of the nonvolatile content of the polymer composition layer. On the other hand, from the viewpoint of the adhesion of the polymer composition layer, the content of calcium oxide is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, based on 100% by mass of the nonvolatile content of the polymer composition layer.

Commercially available calcium oxide products can be used. Examples of commercially available products include "QC-X" manufactured by Inoue Seki Kogyo Co., Ltd.; "Moistop #10" manufactured by Sankyo Flour Milling Co., Ltd.; "HAL-G", "HAL-J", and "HAL-F" manufactured by Yoshizawa Seki Kogyo Co., Ltd.; and "CaO Nano Powder" manufactured by Filgen.

In the present invention, a mixture containing calcium oxide may be used as the hygroscopic filler. An example of such a mixture is calcined dolomite (a mixture containing calcium oxide and magnesium oxide). Calcined dolomite is available, for example, from Yoshizawa Lime Industry Co., Ltd.

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 increase the interfacial bonding strength between calcium oxide, etc. and the polymer. These particle sizes are the median sizes of the particle size distribution when the particle size distribution is created on a volume basis by laser diffraction scattering particle size distribution measurement (JIS Z 8825).

The polymer composition layer may contain a hygroscopic filler other than calcium oxide (hereinafter, sometimes referred to as "other hygroscopic filler"). Examples of other hygroscopic fillers include semi-calcined hydrotalcite, calcined hydrotalcite, magnesium oxide, and molecular sieves. Only one type of other hygroscopic filler may be used, or two or more types may be used in combination. The content of the hygroscopic filler 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 nonvolatile content of the polymer composition layer.

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

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

The crosslinked olefin polymer is preferably formed from an olefin polymer having a carboxy 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 carboxy group and/or an acid anhydride group and the olefin polymer having an epoxy group may each be used alone or in combination of two or more types.

The "olefin-based polymer" portion of the crosslinked olefin-based polymer, the olefin-based polymer having a carboxy group and/or anhydride group, and the olefin-based polymer having an epoxy group will be explained below.

The olefin units of the olefin-based 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.

The olefin polymer may be a homopolymer or a copolymer such as a random copolymer or a block copolymer. Examples of the copolymer include copolymers of two or more kinds of olefins, and copolymers of an olefin with a non-conjugated diene, styrene, or other monomer other than an olefin. 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, isobutylene-isoprene copolymers, and the like.

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

When the butene-based polymer is a copolymer, examples of the monomer other than butene include styrene, ethylene, propylene, isoprene, etc. When the propylene-based polymer is a copolymer, examples of the monomer other than propylene include ethylene, butene, isoprene, etc.

It is preferable that the olefin-based polymer is amorphous from the viewpoint of suppressing a decrease in fluidity due to thickening of the varnish. Here, "amorphous" means that the olefin-based polymer does not have a clear melting point. For example, an olefin-based polymer that does not show a clear peak when the melting point is measured by DSC (differential scanning calorimetry) can be used.

Next, an olefin-based polymer having a carboxy group and/or an acid anhydride group will be described. Examples of the acid anhydride group include a group derived from succinic anhydride, a group derived from maleic anhydride, and a group derived from glutaric anhydride. As the olefin-based polymer having a carboxy group and/or an acid anhydride group, a butene-based polymer having a carboxy group and/or an acid anhydride group and a propylene-based polymer having a carboxy group and/or an acid anhydride group are preferred, and a butene-based polymer having an acid anhydride group and a propylene-based polymer having an acid anhydride group are more preferred.

The concentration of carboxy groups in the olefin polymer having carboxy groups is preferably 0.05 to 10 mmol/g, more preferably 0.1 to 5 mmol/g. The concentration of carboxy groups is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, according to the description of JIS K 2501.

The concentration of the acid anhydride groups in the olefin-based polymer having the acid anhydride groups is preferably 0.05 to 10 mmol/g, more preferably 0.1 to 5 mmol/g. The concentration of the acid anhydride groups is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, according to the description of JIS K 2501.

In an olefin-based polymer having both carboxy groups and acid anhydride groups, the sum of the concentration of carboxy groups and the concentration of acid anhydride groups is preferably 0.05 to 10 mmol/g, and more preferably 0.1 to 5 mmol/g.

An olefin-based polymer having a carboxy group and/or an acid anhydride group can be obtained, for example, by graft-modifying an olefin-based polymer with an unsaturated compound having a carboxy group and/or an acid anhydride group under radical reaction conditions. Also, an olefin-based polymer having an acid anhydride group can be obtained by radical copolymerizing an unsaturated compound having a carboxy group and/or an acid anhydride group with an olefin or the like.

The olefin polymer having a carboxy group and/or anhydride group may be a commercially available product. Examples of commercially available products include "T-YP279" manufactured by Seiko PMC (maleic anhydride modified propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 36% by mass, acid anhydride group concentration: 0.464 mmol/g, number average molecular weight: 35,000), and "T-YP312" manufactured by Seiko PMC (maleic anhydride modified propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 29% by mass, acid anhydride group concentration: 0.464 mmol/g, number average molecular weight: 60,900), Seiko PMC's "ER661" (maleic anhydride modified isobutylene-isoprene random copolymer, acid anhydride group concentration 0.87 mmol/g, number average molecular weight: 39,700), Toho Chemical Industry's "HV-300M" (maleic anhydride modified liquid polybutene ("HV-300" (number average molecular weight: 1,400) modified product), number average molecular weight: 2,100, number of carboxy groups constituting acid anhydride group: 3.2/molecule, acid value: 43.4 mgKOH/g, acid anhydride group concentration: 0.77 mmol/g), etc.

Next, an olefin-based polymer having an epoxy group will be described. As an olefin-based polymer having an epoxy group, a butene-based polymer having an epoxy group and a propylene-based polymer having an epoxy group are preferable.

The concentration of epoxy groups in the epoxy group-containing olefin polymer is preferably 0.05 to 10 mmol/g, more preferably 0.1 to 5 mmol/g. The epoxy group concentration is determined from the epoxy equivalent obtained based on JIS K 7236-1995.

Olefin-based polymers having epoxy groups can be obtained by graft-modifying an olefin-based polymer under radical reaction conditions with an unsaturated compound having an epoxy group, such as glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, or allyl glycidyl ether. In addition, an olefin-based polymer having epoxy groups can be obtained by radical copolymerization of an unsaturated compound having an epoxy group with an olefin or the like.

Commercially available olefin polymers having epoxy groups may be used. Examples of such commercially available products include "T-YP341" manufactured by Seiko PMC (glycidyl methacrylate modified propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 29% by mass, epoxy group concentration: 0.638 mmol/g, number average molecular weight: 155,000), and "T-YP276" manufactured by Seiko PMC (glycidyl methacrylate modified propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 36% by mass, epoxy group concentration: 0.638 mmol/g, number average molecular weight: 155,000). ol/g, number average molecular weight: 57,000), Seiko PMC's "T-YP313" (glycidyl methacrylate modified propylene-butene random copolymer, amount of butene units per total of propylene units and butene units: 29 mass%, epoxy group concentration: 0.638 mmol/g, number average molecular weight: 155,000), Seiko PMC's "ER850" (glycidyl methacrylate modified isobutylene-isoprene random copolymer, epoxy group concentration: 0.654 mmol/g, number average molecular weight: 99,200), etc.

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

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

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

From the viewpoint of adhesion and flexibility, the polymer composition layer preferably contains an olefin-based polymer that does not have a crosslinked structure (hereinafter, may be referred to as a "non-crosslinked olefin-based polymer"). Only one type of non-crosslinked olefin-based polymer may be used, or two or more types may be used in combination. The explanation of the "olefin-based polymer" portion of the non-crosslinked olefin-based polymer is the same as the explanation of the "olefin-based polymer" portion of the crosslinked olefin-based polymer, etc. described above.

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

Non-crosslinked olefin-based polymers may be commercially available products. Examples of 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 units 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).

The number average molecular weight of the above-mentioned olefin polymer having an acid anhydride group, olefin polymer having an epoxy group, and non-crosslinked olefin polymer is preferably 1,000,000 or less, more preferably 750,000 or less, even more preferably 500,000 or less, even 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, etc. On the other hand, from the viewpoint of preventing repelling during application of the varnish of the polymer composition, expressing the sealing performance of the formed polymer composition layer, and improving the mechanical strength, the number average molecular weight is preferably 1,000 or more, more preferably 2,000 or more. The number average molecular weight in the present invention is measured by gel permeation chromatography (GPC) method (polystyrene equivalent). Specifically, the number average molecular weight according to the GPC method can be measured using a Shimadzu Corporation "LC-9A/RID-6A" measuring device, a Showa Denko Corporation "Shodex K-800P/K-804L/K-804L" column, toluene or the like as the mobile phase, at a column temperature of 40°C, and calculated using a calibration curve of standard polystyrene.

The polymer composition layer may contain components other than those described above (hereinafter, sometimes referred to as "other components") to the extent that the effects of the present invention are not impaired. Examples of other components include tackifiers, curing accelerators, antioxidants, plasticizers, etc. These may be used alone or in combination of two or more.

The tackifier is a component that imparts adhesion to the polymer composition layer. Examples of tackifiers include rosin-based resins, terpene resins, modified terpene resins (hydrogenated terpene resins, terpene-phenol copolymer resins, aromatic modified terpene resins, etc.), petroleum resins (aliphatic petroleum resins, hydrogenated petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins), coumarone-indene resins, alkylphenol resins, xylene resins, etc.

Commercially available tackifiers can be used. Examples of such commercially available products include the following. Examples of rosin-based resins include 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 Co., Ltd.).

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.).

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

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.).

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

Examples of hydrogenated petroleum resins include Escorez 5300 series and 5600 series (all manufactured by Exxon Mobil Corporation); T-REZ OP501, T-REZ PR803, T-REZ HA085, T-REZ HA103, T-REZ HA105, and T-REZ HA125 (all hydrogenated dicyclopentadiene-based petroleum resins manufactured by ENEOS Corporation); Quintone 1325 and Quintone 1345 (all manufactured by Zeon Corporation); Imave S-100, Imave S-110, Imave P-100, Imave P-125, and Imave P-140 (all hydrogenated dicyclopentadiene-based petroleum resins manufactured by Idemitsu Kosan Co., Ltd.); Alcon P-90 and Alcon P-100, Alcon P-115, Alcon P-125, Alcon P-140, Alcon M-90, Alcon M-100, Alcon M-115, Alcon M-135, TFS13-030 (all manufactured by Arakawa Chemical Industries Co., Ltd.), etc.

Examples of aromatic petroleum resins include ENDEX155 (manufactured by Eastman Co.); 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); Petcol LX, Petcol 120, Petcol 130, Petcol 140 (all manufactured by Tosoh); T-REZ RB093, T-REZ RC100, T-REZ RC115, T-REZ RC093, T-REZ RE100 (both manufactured by ENEOS Corporation).

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 Zeon Corporation).

From the viewpoint of the heat resistance of the polymer composition layer, 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. The softening point is measured by the ring and ball method according to JIS K2207.

From the viewpoint of adhesion and sealing properties of the polymer composition layer, 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, relative to 100% by mass of the non-volatile content of the polymer composition layer.

Examples of hardening accelerators include imidazole compounds, tertiary and quaternary amine compounds, dimethylurea compounds, and organic phosphine compounds.

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, 1-cyanoethyl-2-undecylimidazolium 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'))-ethyl-s-triazine, 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine isocyanuric acid adduct, and the like. Specific examples of imidazole compounds include Curesol 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 Chemical Industry Co., Ltd.).

The tertiary and quaternary amine compounds are not particularly limited, 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 salt, DBU-p-toluenesulfonate, DBU-formate salt, 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.

Examples of dimethylurea compounds include aromatic dimethylureas such as DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and U-CAT3512T (manufactured by San-Apro Co., Ltd.); and aliphatic dimethylureas such as U-CAT3503N (manufactured by San-Apro Co., Ltd.). Among these, aromatic dimethylureas are preferably used from the viewpoint of curability.

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, triphenylphosphine triphenylborane, etc. Specific examples of organic phosphine compounds include TPP, TPP-MK, TPP-K, TTBuP-K, TPP-SCN, TPP-S (all manufactured by Hokko Chemical Industry Co., Ltd.), etc.

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, relative to 100% by mass of the nonvolatile content of the polymer composition layer, in order to promote the formation of an olefin-based polymer having a crosslinked structure.

In the present invention, there is no particular limitation on the antioxidant, and any known antioxidant can be used. When an antioxidant is used, the content is preferably 0.01 to 5 mass %, more preferably 0.05 to 2.5 mass %, and even more preferably 0.1 to 2 mass %, relative to 100 mass % of the nonvolatile content of the polymer composition layer.

Examples of plasticizers include mineral oils such as paraffin-based process oil, naphthenic process oil, liquid paraffin, and Vaseline, and vegetable oils such as castor oil, cottonseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, and olive oil.

The sealing sheet of the present invention has a laminated structure including, in this order, a support, a polymer composition layer, and a protective sheet. 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. Both the support and the protective sheet may be single-layer films or laminated films.

In the protective sheet, the surface in contact with the polymer composition layer is preferably release-treated. On the other hand, the support may or may not be release-treated. Examples of release treatments include release treatments using a release agent such as a silicone resin-based release agent, an alkyd resin-based release agent, or a fluororesin-based release agent.

The thickness of the support and the protective sheet is not particularly limited, but from the viewpoint of the handleability of the sealing sheet, etc., it is preferably 10 to 150 μm, more preferably 20 to 100 μm, respectively. When the support and the protective sheet are laminated films, the above thickness is the thickness of the laminated film. On the other hand, from the viewpoint of sealing property, etc., 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.

The water vapor transmission rate (hereinafter sometimes referred to as "WVTR") of the support and the protective sheet is preferably 1 (g/m ² /24hr) or less. Here, the "water vapor transmission rate (g/m ² /24hr)" of the sheet means the amount of water vapor (g) that passes through a sheet with an area of 1 m ² in 24 hours under the conditions of a predetermined temperature and humidity described below. By using a low moisture-permeable support and a low moisture-permeable protective sheet having a water vapor transmission rate of 1 (g/m ² /24hr) or less, it is possible to prevent moisture absorption of the polymer composition layer during storage of the sealing sheet. In addition, when a low moisture-permeable support and a low moisture-permeable protective sheet are used, it is generally difficult to pre-dry the sealing sheet. In this regard, in the present invention, the moisture content of the polymer composition layer can be sufficiently reduced during the production of the sealing sheet (particularly during aging) by using a large amount of calcium oxide as described above, so that the pre-drying of the sealing sheet can be omitted.

The "water vapor transmission rate (g/ ^m2 /24hr)" of the sheet can be measured by a water vapor transmission rate measuring device PERMATRAN series manufactured by MOCON Co., Ltd. (in accordance with ISO 15106-2, JIS K7129B). Specifically, the sheet is cut into ⁵⁰ cm2 pieces, set in a jig using silicone grease, and then adjusted to conditions of a temperature of 40°C and a humidity of 90% RH using ultrapure water, and the water vapor transmission rate is measured until it reaches a steady state.

For example, a film having a barrier layer, or a laminate film of a film having a barrier layer and another film can be used as the low moisture permeable support and the low moisture permeable protective sheet. Examples of the barrier layer include inorganic films such as silica vapor deposition films, silicon nitride films, and silicon oxide films. The barrier layer may be composed of multiple layers of multiple inorganic films (e.g., silica vapor deposition films). The barrier layer may also be composed of an organic material and an inorganic material, or may be a composite multilayer of an organic layer and an inorganic film.

As a 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 high-barrier plastic films include those manufactured by laminating inorganic films such as silicon oxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon nitride oxide, SiCN, and amorphous silicon on the surface of a plastic film in a single layer or multiple layers by chemical vapor deposition (e.g., chemical vapor deposition using heat, plasma, ultraviolet light, vacuum heat, vacuum plasma, or vacuum ultraviolet light) or physical vapor deposition (e.g., vacuum deposition, sputtering, ion plating, laser deposition, molecular beam epitaxy, etc.) (see, for example, JP 2016-185705 A, JP 5719106 A, JP 5712509 A, JP 5292358 A, etc.). In order to prevent cracks in the inorganic film, it is preferable to alternately laminate the inorganic film and a transparent flattening layer (for example, a transparent plastic layer).

As a film having a barrier layer, for example, a medium-barrier plastic film having a WVTR of 0.01 (g/ ^m2 /24hr) or more and 1 (g/ ^m2 /24hr) or less can be used. Examples of medium-barrier plastic films include those manufactured by depositing an inorganic film containing an inorganic substance such as silicon oxide (silica), aluminum oxide, magnesium oxide, silicon nitride, silicon nitride oxide, SiCN, or amorphous silicon on the surface of a substrate 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, JP 2013-108103 A and JP 4028353 A).

Commercially available products may be used as films having a barrier layer. Examples of commercially available medium-barrier plastic films include "Kurarista CI" manufactured by Kuraray Co., Ltd., "Techbarrier HX", "Techbarrier LX" and "Techbarrier L" manufactured by Mitsubishi Chemical Corporation, "IB-PET-PXB" manufactured by Dai Nippon Printing Co., Ltd., and "GL, GX Series" manufactured by Toppan Printing Co., Ltd., and examples of commercially available high-barrier plastic films include "X-BARRIER" manufactured by Mitsubishi Chemical Corporation.

The sealing sheet and polymer composition layer of the present invention can be produced, for example, by (1) dissolving the above-mentioned components in an organic solvent to prepare a varnish of the polymer composition, (2) applying the obtained varnish onto 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 moisture content of the polymer composition layer by heating the obtained laminate for aging.

Examples of organic solvents that can be used to prepare the varnish include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetate 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 the like. Only one type of organic solvent may be used, or two or more types may be used in combination. Commercially available organic solvents may be used. Examples of such commercially available products include "Swasol" manufactured by Maruzen Petrochemical Co., Ltd. and "Ipsol" manufactured by Idemitsu Kosan Co., Ltd. The varnish can be applied by a known method (for example, a method using a die coater), and there is no particular limitation on the application method.

The coating is preferably dried by heating in order to form an olefin-based polymer having a crosslinked structure. The coating is dried at a temperature of preferably 50 to 200°C, more preferably 80 to 150°C, for a time of preferably 1 to 60 minutes, more preferably 10 to 30 minutes. Drying may be performed under normal pressure or under reduced pressure.

The protective sheet can be laminated onto the polymer composition layer using known equipment. Examples of such equipment include a roll laminator, a press, and a vacuum pressure laminator.

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

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 an electronic device that is sensitive to moisture, such as an organic EL device or a solar cell. The sealing sheet of the present invention can also be used to seal conductive substrates, etc.

The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the above and below aims, all of which are included in the technical scope of the present invention. Note that "parts" and "%" in the amounts of components and copolymerized units mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

<Ingredients>
The components used in the examples and comparative examples are shown below.
(Olefin-based polymer)
"T-YP341" (Seiko PMC Corporation, glycidyl methacrylate modified propylene-butene random copolymer, propylene unit/butene unit: 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" (ENEOS Corporation, liquid polybutene, number average molecular weight: 2,900)

(hygroscopic 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 ("DHT-4C" manufactured by Kyowa Chemical Industry Co., Ltd., particle size (median size): 400 nm, BET specific surface area: 15 m ² /g)
Calcined hydrotalcite (KW2200 manufactured by Kyowa Chemical Industry Co., Ltd., particle size (median size): 400 nm, BET specific surface area: 190 m ² /g)
Magnesium oxide ("DIPSERMAG" manufactured by Tateho Chemical Industries, Ltd.)
Molecular sieve 4A (Union Showa)

(Tackifier)
"T-REZ HA105" (manufactured by ENEOS, hydrogenated alicyclic petroleum resin, softening point: 105°C)

(Antioxidant)
"Irganox 1010" (BASF, hindered phenol-based antioxidant)

(Cure Accelerator)
2,4,6-tris(dimethylaminomethyl)phenol (hereinafter abbreviated as "TAP") (manufactured by Nouryon Chemical Industries, Ltd.)

Example 1
A varnish having the compounding ratio shown in the following table was prepared by the following procedure, and a sealing sheet was prepared using the obtained varnish. The amount (parts) of each component shown in the following table indicates the amount of non-volatile content of each component in the varnish. The following table also shows the amount of hygroscopic filler added relative to 100% by mass of non-volatile content of the varnish.

Specifically, a mixture was obtained by dispersing maleic anhydride-modified liquid polybutene (Toho Chemical Industry Co., Ltd.'s "HV-300M"), liquid polybutene (ENEOS Corporation's "HV-1900"), and calcium oxide (Yoshizawa Lime Industry Co., Ltd.'s median diameter: 2.1 μm) in a Swagel solution (non-volatile content: 60%) of hydrogenated alicyclic petroleum resin (tackifier, ENEOS Corporation's "T-REZ HA105") using a three-roll mill. The resulting mixture was mixed with a Swazol solution (non-volatile content: 15%) of glycidyl methacrylate modified propylene-butene random copolymer (T-YP341 manufactured by Seiko PMC), a hindered phenol antioxidant (Irganox 1010 manufactured by BASF), a curing accelerator (TAP, manufactured by Kayaku Nouryon) and toluene, and the resulting mixture was uniformly dispersed in a high-speed rotating mixer to obtain a varnish of the polymer composition (non-volatile content: 63%).

A polyethylene terephthalate film with one side treated with a silicone-based release agent ("SP4020" manufactured by Toyo Cross Co., Ltd., PET film thickness: 50 μm) and a low moisture permeable polyethylene terephthalate film ("Techbarrier HX" manufactured by Mitsubishi Chemical Corporation, PET film thickness: 12 μm) were laminated together so that the side of SP4020 not treated with the silicone-based release agent was in contact with Techbarrier HX to prepare a laminated film, which was used as a support and protective sheet for a sealing sheet (laminated film thickness: 62 μm, water vapor permeability of laminated film: 0.12 (g/ ^m2 /24hr)). Hereinafter, the "side of laminated film treated with silicone-based release agent" will be referred to as the "release-treated side".

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

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

Example 2
A varnish of the polymer composition 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, except that the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) used was changed from 200 parts to 260 parts.

Example 3
A varnish of the polymer composition 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, except that the amount of calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) used was changed from 200 parts to 390 parts.

Example 4
A varnish of the polymer composition 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, except that calcium oxide (manufactured by Yoshizawa Sekikogyo Co., Ltd., median diameter: 2.1 μm) was used instead of calcium oxide (manufactured by Yoshizawa Sekikogyo Co., Ltd., median diameter: 1.8 μm).

<Comparative Example 1>
A varnish of the polymer composition and a sealing sheet having a polymer composition layer with a thickness of 50 μm were produced in the same manner as in Example 1, except that the hygroscopic filler was changed 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").

<Comparative Example 2>
A varnish of the polymer composition 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, except that the hygroscopic filler was changed 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").

<Comparative Example 3>
A varnish of the polymer composition 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, except that the hygroscopic filler was changed from calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., median diameter: 2.1 μm) to magnesium oxide (manufactured by Tateho Chemical Industry Co., Ltd., "DISPERMAG").

<Comparative Example 4>
A varnish of the polymer composition 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, except that the hygroscopic filler was changed 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.).

<Comparative Example 5>
A varnish of the polymer composition and a sealing sheet having the polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 1, except that the aging conditions were changed to 130° C. and 24 hours.

<Comparative Example 6>
A varnish of the polymer composition and a sealing sheet having the polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 2, except that the aging conditions were changed to 130° C. and 24 hours.

<Comparative Example 7>
A varnish of the polymer composition and a sealing sheet having the polymer composition with a thickness of 50 μm were prepared in the same manner as in Comparative Example 3, except that the aging conditions were changed to 130° C. and 24 hours.

<Moisture Content of Polymer Composition Layer>
The encapsulating 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 encapsulating sheets, and the obtained polymer composition layer was folded and placed in a dried screw vial ("VABH17" manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and placed in an electric furnace ("VA-236S" manufactured by Mitsubishi Chemical Analytech Co., Ltd.) directly connected to a Karl Fischer measuring instrument ("CA310" manufactured by Mitsubishi Chemical Analytech Co., Ltd.). In an _N2 gas stream, the temperature of the electric furnace was raised to 250 ° C., and the water desorbed from the measurement sample was collected in a Karl Fischer measurement solution, and the mass of the water was measured by a standard method. From the measured mass of water, the water content (ppm) of the polymer composition layer was calculated based on the mass of the entire polymer composition layer. The results are shown in the table below.

The water vapor barrier properties of the polymer composition layers of the sealing sheets obtained in the Examples and Comparative Examples were evaluated by the following method.

<Method for evaluating water vapor barrier properties>
A composite film having an aluminum foil and a polyethylene terephthalate film ("PET-Tuki AL1N30" manufactured by Tokai Toyo Aluminium Sales Co., Ltd., aluminum foil thickness 30 μm, PET film thickness 25 μm) was prepared as a support (water vapor permeability of the composite film: 0.001 (g/ ^m2 /24 hr) or less).

Except for using the composite film as the support, a test sheet having a laminated structure of "support (composite film)/polymer composition layer/protective sheet (laminate film)" was obtained in the same manner as in each of the Examples and Comparative Examples. The polymer composition layer was formed on the aluminum foil of the composite film.

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

After drying, calcium was vapor-deposited onto one side of the glass plate using a mask that covered the peripheral area 0 mm to 2 mm from the edge of the glass plate. As a result, a calcium film 200 nm thick (purity: 99.8%) was formed in the central portion of one side of the glass plate, excluding the peripheral area 0 mm to 2 mm from the edge of the glass plate.

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

In general, when calcium comes into contact with water and becomes calcium oxide, it becomes transparent. In the above-mentioned evaluation sample, the glass plate and aluminum foil have sufficiently high water vapor intrusion barrier properties, so that moisture usually moves in the in-plane direction (direction perpendicular to the thickness direction) through the edge of the polymer composition layer to reach the calcium film. When moisture reaches the calcium film, the calcium film is gradually oxidized from the edge and becomes transparent, so that the calcium film is observed to shrink. Therefore, the intrusion of moisture into the evaluation sample can be evaluated by measuring the sealing distance (mm) from the edge of the evaluation sample to the calcium film. Therefore, the evaluation sample containing the calcium film can be used as a model of an electronic device.

First, the initial sealing distance X2 (mm) from the end of the evaluation sample to the end of the calcium film was measured using a microscope (Mitutoyo Corporation's "Measuring Microscope MF-U").

Next, the evaluation sample was placed in a thermo-hygrostat set at a temperature of 85° C. and a humidity of 85% RH. When the sealing distance X1 (mm) between the end of the evaluation sample placed in the thermo-hygrostat and the end of the calcium film increased by 0.1 mm from the initial sealing distance X2, the evaluation sample was removed from the thermo-hygrostat. The time from the time the evaluation sample was placed in the thermo-hygrostat to the time the evaluation sample was removed from the thermo-hygrostat was determined as the decrease start time t (hours). This decrease start time t corresponds to the time from the time T _P1 when the evaluation sample was placed in the thermo-hygrostat to the time T _P2 when the sealing distance X1 (mm) between the end of the evaluation sample placed in the thermo-hygrostat and the end of the calcium film becomes "X2+0.1 mm".

The above sealing distance X1 and decrease start time t were applied to the Fick diffusion equation in formula (1) to calculate the constant K as a water vapor intrusion barrier parameter.

Using the obtained constant K, the ability of the polymer composition layer to suppress the penetration of moisture (water vapor barrier property) was evaluated according to the following criteria. The smaller the value of the constant K, the higher the water vapor barrier property. In the following, "hr" means "hours". The results are shown in the table below. In the table, "(cm/hr^0.5)" means "(cm/hr ^0.5 )".
(Water vapor barrier standard)
◯: Constant K is less than 0.02 cm/hr ^0.5 ×: Constant K is 0.02 cm/hr ^0.5 or more

As shown in the above table, 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 having a low moisture content and excellent water vapor barrier properties was formed. On the other hand, in Comparative Examples 1 to 7, in which semi-calcined hydrotalcite, calcined hydrotalcite, magnesium oxide, or molecular sieve 4A was used as the hygroscopic filler, the moisture content of the polymer composition layer could not be sufficiently reduced. In particular, in Comparative Examples 5 to 7, the moisture content of the polymer composition layer could not be sufficiently reduced even though aging was performed for 24 hours.

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, etc.

Claims (7)

A sheet for sealing having a laminated structure including a support, a polymer composition layer, and a protective sheet in this order,
the polymer composition layer comprises an olefin-based polymer having a crosslinked structure and calcium oxide;
A sealing sheet, wherein a content of calcium oxide is 40% by mass or more and 80% by mass or less , based on 100% by mass of nonvolatile content of the polymer composition layer, and a moisture content of the polymer composition layer is 500 ppm or less, based on the mass of the entire polymer composition layer. 2. The sealing sheet according to claim 1 , wherein the olefin-based polymer having a crosslinked structure is formed from an olefin-based polymer having a carboxy group and/or an acid anhydride group, and an olefin-based polymer having an epoxy group. The encapsulating sheet according to claim 1 or 2 , wherein the support and the protective sheet each have a water vapor permeability of 1 (g/m ² /24 hr) or less. The encapsulating sheet according to any one of claims 1 to 3 , which is used for encapsulating an electronic device. The encapsulating sheet according to claim 4 , wherein the electronic device is an organic EL device or a solar cell. A polymer composition layer comprising an olefin-based polymer having a crosslinked structure and calcium oxide,
A polymer composition layer having a calcium oxide content of 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 a moisture content of the polymer composition layer of 500 ppm or less, based on the mass of the entire polymer composition layer. The polymer composition layer according to claim 6 , wherein the olefin-based polymer having a crosslinked structure is formed from an olefin-based polymer having a carboxy group and/or an acid anhydride group, and an olefin-based polymer having an epoxy group.